texts:
I have a question related to small battery connections.

I am working on a project where the design has to be kept as small as possible. I need 3.3V regulated supply and run two small coin vibration motors rated at 3V.

I built this network of coin batteries comprising of 3V button cells and 1.5V button cells. I want to use 4.5V to be regulated down to 3.3V (which can be used for digital circuits). And I want to run vibration motors of the same battery network but use only the two 3V cells. I have connected the two cells in parallel. By doing so would it affect my 4.5V supply? I am not sure about how effective this network would be. Hoping I will get some answers as to how efficient this could be or any recommendations.


texts: Is it possible to connect the center taps of two Ethernet magnetics to each other back-to-back to pass the power from one port to another. Does it make sense? Is anything special required?


texts: The number of the cells required for supplying power to an embedded system

texts:
I'm designing a battery powered embedded system. The system consists of mainly the Raspberry Pi zero & Raspberry Pi Camera V2 and some other sensor modules. This system is supposed to capture still images in sequence for 4 hours with certain time interval and measures some environmental observables. An important condition is that the ambient temperature would be around -40\$^{\circ}\$C. I wanted to ask you if my calculation of the number of battery cells required for this application is valid.

For this calculation I would suppose that the TL5930 from Tadiran will be used. Also a boost converter(switching regulator) with an efficiency of 90% will be assumed. The Raspberry Pi requires its power supply to generate 5V output. The maximum power consumption of the Raspberry Pi, Raspberry Pi camera and others are measured by myself, and I would like to assume here the devices consume 3.0W(5V*600mA) in total continuously. (Please assume this value)

Then from the power consumption of 3.0W and the conversion efficiency of 90%. I find the power that should be supplied to the voltage regulator is
$$
P_{in} = P_{out} \times \frac{1}{\eta} = 3.0W \times \frac{100}{90} = 3.3W \qquad \quad [1]
$$

Now I need to know how many batteries and which configuration I need in order to supply 3.3W for about 4 hours. I looked at the plots 'Voltage vs Temperature' and 'Capacity vs Current' in the datasheet of the TL5930 and found one needs to make assumption of the discharge rate to estimate the terminal voltage and the capacity of the battery. I suppose that the current load would be 230mA. Then in the condition of \$ T=-40^{\circ} \$ and \$I_{d}=230mA\$, the terminal voltage of the cell would be \$V_{BAT}=2.2V\$, and the capacity would be \$Q_{BAT}=0.5Ah\$. Assuming that I connect cells in parallel and convert 2.2V to 5V. The total current draw from the batteries  to the voltage regulator is
$$
I_{in}=3.3W/2.2V=1.43A \qquad \quad (2)
$$
Since I already made an assumption of the discharge rate and derived voltage as well as capacity, here I again assume that the discharge rate for each battery will be \$I_{d}=230mA\$
$$
0.23A\times N = 1.43A. \qquad \quad (3)
$$
$$
N=6.22. \quad (4)
$$

If I have less than 6 cells, the current would exceed 230mA. This is not recommended, because the maximum recommended continuous current of the TL5930 is 230mA. Therefore I need 7 cells connected in parallel.

To me the calculation seems odd. The discharge rate would be less than 230mA this time, and it is inconsistent with my initial assumption. I would need to change my initial assumption of the terminal voltage and the capacity. Then I will get a different discharge rate in the end. Could you please let me know what is wrong in my calculation?


texts:
don't know if this is the right place to ask such a question but i'll try.
I opened up my DMM to check fuses. Now I would like to close it but before I can do this I have to put in the right place the range selector switch, but how can I do it? I don't know how the switch position relate to the position I see in the multimeter case..

Hope the explanation is clear.

Model is Finest 201


texts: DIY Induction Heater failure - MOSFET overheat

texts:
I saw this video about DIY Induction Heater and I decided to make it by myself in order to learn something from this project.

After finish wiring everything, I connect the power supply and heard/saw a spark. I touched the components and the two MOSFET were super hot. I supposed that I connected something wrong / shortened something so I rebuilt the circuit  with new components, with more space between them, and before turning it on, I checked connectivity with a multimeter to verify everything is well connected.

On the second time I also limited my power supply to 3 Amps. When I connected it to the circuit, the voltage of the power supply dropped to 5.4V (because of the 3A limit) and I felt the MOSFETS are becoming again very hot.

I also built this circuit in an online simulator but it seems to behave differently. I couldn't think of any solution, hope you guys can help.

This is the schematic:

L2, L3:

Inductance: 100uH,
Current Rate: 6A

L1: 3uH. 2mm thick Pure Copper Wire Round Solid Uncoated with 10 turns of 20mm diameter.

Capacitors: 2 x WIMA MKP10 0.33uF (0,33µF 330nF) 400V 5% pitch:22.5mm Capacitor

This is how I connected everything:

Power Supply before connecting:

Power Supply after connecting:


texts: How can I eliminate the noise in this case?

texts:
As a part of a big system Arduino is being affected from a switch outside(so the spike is not always there only when an outside switch or surge happens ect.) and I guess through its USB producing spikes on its output. Arduino is set normally to output around 40Hz pulse train and when the spike hits it upsets the Device it couples to below:

I dont have enough time to figure out all the system and block whats happening. I rather want to eliminate or filter the spike which looks like below:

I have a scope screenshot but it is not very good one that's why I draw it above. But anyway below is the screenshot the pink one is the pulse signal.

You can see the spike above during the pulse ON time.

How can I eliminate this spike? Would a low pass filter, zener didoe or an opto-isolator help? Is there a topology at the output of the pulse signal from Arduino I can try out? A such topology drawn circuit would help in an answer.

And here are how the 12VDC 5VDC power supplies and a 10VAC step down 10step down transformer is affected by the switch in the same system:

Edit:

I treied to simulate the spike and use an RC and a schmitt trigger with hysteresis as suggested:

Signals at input, output and comparator's inverting and non-inverting terminals:

I put R6 C5 to suppress the spike in the system to not to upset comparator, is that a fine way to filter the spike from Vcc? What do you think about the circuit?


texts: is it safe/practical to control this 30A+ motor with mosfet?

texts:
I'm thinking of controlling a few high ampere water pumps from microchips.
the current draws of motors will be around 38A (single phase 220V motors).
is it safe to use a MOSFET (IPW60R070C6 from Infineon, Datasheet) for this purpose ? (assuming a well designed thermal solution w/ heat-sinks for mosfets)
the mosfet ratings seem OK (600V, 53A) and the motors will be on for ~2 hours continuously per day.
if this is safe why using SSR and other mechanical heavy-duty relays is common ?


texts: Does "50Mhz Oscilloscope" mean that it can plot up to only 50Mhz frequencies or its bandwith is 50Mhz?

texts: I couldn't find it in the books. I mean the fixed freq. value on the oscilloscope.


texts: Resistor Power Rating and headroom for AC circuit

texts:
Background

I'm going to put together a resistive load, to load a 100W source with an \$8\Omega\$ or \$16\Omega\$ resistor.  I'm finding that when to use peak, peak-to-peak or RMS values of voltage, current or power is a subject still shrouded in mystery for those new to the subject or not working in the industry.

Understanding which power to use (RMS, Peak or Peak-to-peak)

When selecting a power rating for the resistor

do you assume that the power rating on the component website is for a DC supply
should you calculate the power rating of a component from the RMS power, Peak Power or Peak-to-peak power?

Example:
Without taking into account the extra headroom needed (let's run this resistor at maximum permissible power),
$$100W_{RMS}=200W_{Peak}=400W_{Peak-to-Peak}$$
 therefore should you select a 400W resistor?

Headroom

What is the convention when it comes to selecting headroom on the component's power rating.  Is, 1.2 - 1.5 a reasonable factor to multiply by.  Let's for the sake of safety put a fuse in line with the resistor to protect it.

My intuition

My intuition tells me to place a fuse in series and either:

work with the Peak power value in mind because the AC signals will only ever reach a maximum of the peak value, not the peak-to-peak value, and to select headroom in the region of a factor of 1.25 - 1.50.  From the example, this would mean selecting a resistor with power rating of \$200W_{Peak} \cdot 1.2 = 250W\$ or \$200W_{Peak} \cdot 1.50 = 300W\$.

or

work with the peak-to-peak power value which according to the logic in the previous bullet point will surpass the peak power value by a factor of 2 and not chose to use additional headroom. From the example, this would mean selecting a resistor with power rating of \$400W_{Peak-to-peak} = 400W\$

Of these two estimations, the second seems to be sensible due to the apparent large headroom, and therefore component lifespan, but perhaps at an extra financial cost.

Simplification of finding a component

To make it easier to find components within a restricted budged (in the tens of pounds rather than hundreds of pounds) I intend to connect a number of resistors in parallel to distribute the current and therefore power/ component heating. i.e. \$5 \times 40\Omega\$ resistors in parallel \$=8\Omega\$ and \$5 \times 80\Omega\$ resistors in parallel \$=16\Omega\$.

What say you? Thanks in advance

Daniel


texts:
I have set up my Arduino UNO with 4 input wires, they connect to the port 10, 11, 12, 13, they  are connected to my breadboard with nothing on it but the wire.

My code would simply be:

Serial.println(digitalRead(13));
Serial.println(digitalRead(12));
Serial.println(digitalRead(11));
Serial.println(digitalRead(10));

The thing is, after I briefly connect a pin to 5V or 3V3, the reading would start going nuts like:
1 0 0 1 0 1 1 1 0 1 0 1 1 0
Without any sense! Without having any wire connected directly to my VCC (5V or 3V3) the reading is constantly changing, when it should be zero!

Is my Arduino dead? How can I fix this?


texts: Can 1 relay turn one light off and another on?

texts: I have a 24 VDC sensor that connects to a switching amplifier. When the sensor detects a fault it should send a signal to a relay which is connected to a green LED and a red LED. The Green LED should be on all the time unless there is a fault sensed by the sensor. If there is a fault the red LED should come on and the green one should turn off.  Is it possible to do this with just one relay? And how would the wiring schematic go? The input voltage is 120 VAC. The switching amp connects to the sensor on one side through an intrinsically safe barrier.


texts:
I am not just an electrical engineering noobie, I'm an electrical engineering dummy.  (No, you can't use me for testing your newly designed electric chair.)  What I need is a simple, direct answer, to a very narrow question.  I realize that such an answer may not be available.  If that is the case, please feel free to say so.

Here is my understanding:

If you were to plot S11 of a basic electronic component (e.g. capacitor, inductor, resistor) on a Smith Chart, you will get a curve that represents the impedance of that component as it changes with frequency.  Impedance is R + jX, where X represents the reactance (inductance/capacitance) of the component.  At any particular point along the S11 Curve, the Smith chart will display R + jX of the component at a particular frequency.

For commercially produced inductors, manufacturers list a nominal inductance figure, e.g. 100 uH.  They will (or should) also tell you the frequency at which this value was obtained, since inductance of anything is not constant over a range of frequencies.

Here is my question:

In the case of an inductor which the manufacturer lists as 100 uH at 100 kHz, looking at the S11 plot, at the point where the frequency is 100 kHz, should the X, in R + jX be the same as the (nominal) inductance of the inductor?

I understand there are many factors that will affect the accuracy of such a measurement.  Insofar as it is possible, assume that care has been taken to reduce these factors to a minimum, and that, none-the-less, any such measurement will be accompanied by some percentage of error.


texts: Connections between 2 separate isolation transformers

texts: If there are 2 isolated transformers 240v and you connect the secondary grounded centertap of one of them to the secondary  grounded hot of another. What would happen in such scenerio. How would they interact?  I just to understand what would occur if my 2 circuits encounter such hidden interactions.


texts: Can't get 2N3904 transistor to allow the collector current I want, when used as a switch

texts:
I have a 3.7 V 18650 battery and I want to control a 3 V, 130 mA LED (high power CREE LED).

I have calculated the series resistor for the LED (0.7 V/0.130 A) = 5 Ohms (ish)

But when I apply any voltage or current to the base, I don't get the 130 mA at the collector like I want. Instead, the LED is dim and I'm getting considerable  voltage drop over the transistor.

I'm just confused about how to get the transistor to become fully saturated and act like a switch.

From what I understand, the base needs at least 0.7 V and the current Ib needs to be calculated from Ic/gain.

Could someone help me out please?


texts:
There's an outdoor area I'm working on, and I want to build a small station where people can charge their phones. There's no access to house power in the area.  I've looked into solar chargers, but they seem impractical, so I was thinking something like a car battery or other large battery might work.

Is that the best way to do this? I need something that can be removed and charged, and then hooked up to a USB port. Thanks for any help!


texts:
all! First post here.
So I have a DDTS-100 audio decoder, for over 10 years, which I have connected to a TV, several consoles, a PC and occasionally other equipment. It's still working fine, except for a small issue that, has far as I can recall, has always been there, which is audio interference every time an optical or coaxial output is selected. This has always been easily fixed by turning the decoder off and on. Sometimes it may take a couple of times, but the moment it s turned on and there's no interference it will remain that way until the output in question is disconnected and connected again. Anyway, recently I purchased a blu ray drive for my PC, in order to watch blu rays from other regions. As usual, I'd turn the decoder off and on when the movie starts to eliminate interference. The thing is the other way I was watching a movie that uses seamless branching over several scenes, something that would always cause an audio drop that would bring back the interference, which meant I had to keep turning the decoder off and on several times during the movie, something that got old fast. So I finally decided to... see what I could do about it. A Google search didn't return any specific results, I tried to connect the AC adapter to a different outlet, an outlet with nothing else connected to it, and the interference did become less audible, but it's still there, on the optical and coaxial outputs depending on me to turn the decoder off and on to eliminate it. The AC adapter looks to be in perfect condition, it never suffered any damage, but... should I still consider buying a new one? Would that solve my problem? If not... what would? Could the issue have more to do with my apartment's wiring than the equipment?
Thanks in advance :)


texts:
I was tearing down some old CD drives and while taking a look to the PCB I found two pointy solder spots, connected to the first pin of each side of a chip which makes me think is an EEPROM.

There seems to be no trace connecting to these.

What are they used for ?

Here's a picture :

Other odd shaped pads in the same direction :


texts: How to count Collective failure rate for chips?

texts:
i wonder where 0,81 from, from this lecture www.eng.auburn.edu/~agrawvd/COURSE/FULL/lec3.ppt -page 14.
i try find specific area in failure rate, but it seems i can't find 0,81 from
let's say Chips = C , then there's Cn chips that has failure rate,
so the formula would be C1+C2+...Cn - [?] = answer
could anyone understand about this test economic.
thank you


texts: Is Li-Po battery safe to bring in flight

texts:
I am going to bring my device with me on flight, and I have this battery : https://www.coolcomponents.co.uk/lithium-polymer-battery-1000mah.html

installed within the device.

I am wondering if this battery is safe for flight? Should I bring it with me in carry-on luggage or I can put the device in checked in luggage?


texts: Tesla coil - my primary circuit doesn't work

texts:
I would like to make a Tesla coil, so I bought a 10 kV 120 W 30 mA neon sign transformer from Aliexpress.

First potential problem, while playing with it, I noticed that when it stops arcing (because the probes are too far apart), if I put them closer again it doesn't arc anymore and I have to turn off and on the transformer to generate the arc again. From what I saw online, the arc comes back with a regular NST so I don't know if it will be a problem. On the other hand, if I "short circuit" the probes and then separate them everything works fine, the arc is still there.

Next I created a capacitor using wine bottles inside a bucket and salty water, I get around 4.5 nF with 3 bottles. I connected the capacitor in parallel with the NST and I added a spark gap also in parallel (that's all I did for the moment, no secondary or anything, I just wanted to check how it's going to react).

When I power everything on I get no sparks on the spark gap, the NST makes the same sound as if it was "short circuited" but nothing! If I put the probes of the spark gap really close together (like 1 mm or 0,04 inches) I do get some really tiny sparks but I don't get this "high frequency discharge" sound (I mean the tazer sound that we hear on teslas).

Do you know what's the problem? My guess is the way the NST is built, maybe it's not built the same way as a regular one. Also I tried using 2 bottles and 1 so about 2.25 nF and 1.5 nF, same results.

UDAPTE :
@DerStrom8 answered to my question but I'll still send you what I was writing, maybe it will help me for later on, first here is my experimental schematic  Using an online calculator, I know that with my 10 000V and 30 mA, the optimum value for my capacitor is 9.5 nF (of course I will change the value if I find a heavy 50Hz transformer), my capacitor for the moment is less than that so I think it’s ok for experiment purposes. Then I know the formula F = 1/(2pi(L*C)^1/2), which can be used to sinc/tune the frequency or the “primary circuit” and “secondary circuit” (by that I mean the first capacitor/coil and the second “capacitor”/coil). I also know that the easiest way to tune the frequency is to chance the inductance of the “primary coil” as it’s pretty easy. Since most people tune their tesla coil with trial and error, I deduced that If I randomly size my “primary” coil for experiments, I shouldn’t be a problem There is one thing I don’t quite get, tell me if it works like the first option the second, or both are wrong

First : I can almost randomly size my primary coil, I then find my resonance frequency using the capacitance C1 of the wine capacitor and the inductance L1 of my primary that I randomly sized. Then I’ll have to to match this resonance frequency with the correctly sized L2 and C2 of the secondary. And since the calculation won’t be perfect, I then tune a tiny bit the primary coil.

Second : I can’t randomly size the primary coil, and in that case can you tell me how to size it ?

Also, I don’t think I need the secondary circuit to have the spark effect on the spark gap for the experiment. Also, is 9.5 nF the best value to have the largest sparks in the end ?


texts:
I'm designing a controller for the 12V devices in an aquarium. Currently every LED and pump as it's own 12V AC-adapter (all of them max 500mA) so I decided to make a device that controls them all and adds remote control for schedules.

I've read the for the TIP120 and think I've implemented it correctly. DigiStump's Oak (ESP8266-based board) drives I/O pins at 3.3v. Will I be able to switch the desired current per transistor using this design?

You can also checkout the design (Eagle) at Git.io/vMQb9 (but I am not allowed to post more links). If you have other comments on the design in general they are also more than welcome!


texts: Let's say I've got a circuit with a two-pole Thévenin equivalent that has DC voltage difference U and out-resistance Ro. What does the voltmeter do? I suppose it has an internal, very large resistance (Rv) that is connected in parallel with Ro. But what is measured across Rv, and how?


texts: How to find out characteristics of a LED?

texts:
I found a LED somewhere. How can I find out if it has a built-in resistor? As far as I can see, they look really equal to me. Measuring the resistance using the multimeter does show an infinite resistance - I don't know why.
In case there is no built-in resistor, how can I find out the proper limiting resistor? How to find at what voltage the LED should be used?

Similar Q&A can be found here, but it does not oanswere the part about built-in resistors.


texts: In a solar power system, when the panel is off, does the battery determine the wattage?

texts:
I am considering putting together a solar system to power my wireless router when the power goes out. I just have one question that I cannot find the answer to:

Does the wattage of the solar panel matter in my case?

I will be using a 12 V battery and an inverter for after the sun goes down, and a 30 W solar panel seems to be enough to power the router during the day. So after the sun goes down, is the wattage then dependent on the battery? Forgive me if this is a stupid question, I could not find any comprehensive answers.


texts:
I am trying to use an STM32 micro-controller as a USB mass storage device using an AT25SF041 flash  chip for the memory. I know flash integrity degrades over time but its only going to have a file written once or twice during it's lifetime.

My problem is the erase cycle for a 4 KB sector is about 60-300 ms. An interrupt routine is called named
STORAGE_write_FS() and my psuedocode for the rest is as follows

STORAGE_Write_FS(){
  Erase chip
  loop(16 times){
    write segment of 256bytes
  {
}

The problem is i need a way to make sure at least 300ms has passed before writing the bytes.

I am using the SPI library as my chip does not have an FSMC peripheral and so the timings are not directly configurable.

What is the best way to do this without using the HAL_delay(); function?

If I return USBD_BUSY then the device sends a NYET command to the host PC saying its not ready yet.
I'm thinking I could use the systick to evaluate the amount of time that has passed without changing the interrupt flow.

If so, how could I best implement this?

and please give an example if you can. I learn best that way.


texts: Question about 1-bit Analog-to-Digital Converter

texts:
I am working on a research project, and for a part of it I have to turn an analog signal into a digital one.  Now, electronics is not my forte so I don't know what I am doing and am feeling around in the dark.  I have been doing research all of yesterday and today to answer the specific way that I want to do this conversion and I think I have an answer, but I don't know what is best for my project.

Device 1 outputs an analog signal.  This analog signal will stay at voltage low until it pulses for some time t to high.  Then it will return to voltage low.  This analog signal will always be either at voltage low or high.

Device 2 wants to read this signal.  However, it can only receive signals with a UART protocol at its internal baud rate.  The way that Device 2 will understand this signal is by having some Interpreter to parse the information for it at regular intervals into bits b0 and b1 representing "high at this moment" and "low at this moment".

Interpreter is what I want.  Interpreter should check the voltage outputted by Device 1 once every 100 nanoseconds (ideally once every 2 nanoseconds).  If the voltage is high then Interpreter should record a signal b1.  If the voltage is low then Interpreter should records a signal b0.  It should send these bits to Device 2 packaged in a UART protocol so that Device 2 can interpret the bits.  Device 2 will have software to process the bits from there.

I don't know what device to use for Interpreter.  I know that anything that I code would be too slow, so I was hoping to use some device that could do it faster.  At first, I was trying to find a low-bit ADC with a high speed in the >500 MSPS range, but I think that a comparator would work as well.  However, despite my research I haven't been able to settle on a product because I don't know what part would work best for my system.  The only fast ADCs are expensive and I don't know if a comparator is fast enough for me or will output with a UART protocol.  Or, I don't know if there is a part that I could purchase that does the job better than either of them.  So if anyone has any good suggestions I will do research on them.

Thank you.

EDIT: Didn't know that TTL wasn't a protocol, and I realized that I wanted a UART protocol.  Replaced TTL with UART in the post.

EDIT: If I have a sampling rate of 10MHz it will be sufficient, but a sampling rate of 500MHz is desired if it is affordable.

EDIT: If you vote my question down, please let me know why you did.  I am learning and I want constructive feedback.

EDIT: Rewrote the post for clarity and included images below to clarify what I am asking.

Line 1 above shows an example of what could be outputted by Device 1.  Notice that the pulses come at random times but are all of length t (as best as I could draw)
Line 2 above shows what the Interpreter may do before packaging start and stop bits.  Notice that every voltage lines up with the blue lines.  I use the blue lines to show the intervals.
Line 3 above shows what the Interpreter should output to Device 2 after including start/stop bits.


texts: NiMH 1.2V 1/3 AA 280 mAh is it possible the claim made for size and capacity?

texts:
I am browsing some batteries to use for a wearable project.Initially I wanted to go with Lipos but upon stumbling upon this link I am amazed at NiMH and the variety of size, shape and battery capacity. I am not sure if it too good to be true for the capacities claimed here. Does anyone with experience of using NiMh thinks that these claims might be true? Especially given the form factor I am very interested in

NiMH 1/V150H 150 mAh with pins as I can connect a few of these in series to get a higher voltage and get rid of Boost circuit in my project. The form factor also gives me the flexibility to make optimal use of the space to make the circuitry a part of clothing itself. My project sinks 100mA average with pulses at 600mA at 5V. The max time I need for the project to run is 2 hours runtime max as it in Idle the consumption is just 10mA.


texts: Can any power supply be made a current source with this circuit?

texts:
The other day I built a basic buck power supply on a breadboard from scratch (i.e. sawtooth generator, comparator, zener power supplies for control circuitry and references, feedback loop, and low-pass filter for the power output).

It got me thinking - could any off-the-shelf power supply chip be made into a current source using the following arrangement of the feedback?

simulate this circuit – Schematic created using CircuitLab

For the sake of example here, this would be a buck converter with an internal 1V FB reference which has been designed as a 1A current source. Rather than the traditional voltage divider feedback loop for voltage feedback, this uses a 0.01\$ \Omega \$ feedback resistor with some generic amplifier block (could be an IA, could have an active low-pass filter as well for noise/anti-aliasing etc.) with a gain of 100x.

Once the voltage is increasingly ramped until the current through the resistor hits 1A, the feedback voltage will reach 1V - and so the power supply will maintain the voltage (and therefore current) at that level.

Obviously, buck, boost, or buck-boost would have to be chosen appropriately to ensure the output voltage was correctly reachable, over the desired current compliance range.

Any first-glance reasons why this wouldn't work?

Cheers.

EDIT: Decided to simulate it with a basic linear tech buck part. Seems to work (note, this has a reference of 2.21V). Obviously as some have pointed out, the op-amps will affect the transfer function in the feedback loop. I believe as long as the correct op-amps were chosen (high-frequency, high CMRR, proper filtering), this is a viable solution however. Feel free to disagree, but.


texts: How to discern quality of a breakout board? other than proper soldering on back of board

texts:
I see three different breakout boards for a project I am doing yet I am not sure which one to pick. How would i know which is of higher quality?

I do see a metal circle inserts in board two and three which I assume are used to hold the plastic six pin plug in place. other than that I am not sure which of these boards would be better in terms of build quality, overall longevity, and performance?

Board 1:
Board 2:
Board 3:

Any input is appreciated as i am completely new to using such boards and do not want to use something that i am sure to screw up just by handling a bit roughly due to my amateur ways.

Also, when choosing cables that go into these. a seller mentioned that he had 16 guage cables that came with 16 gauge power cables and 18 gauge ground cables.  why would this make any sense. Doesn't that lower the wattage ratting for the entire cable at that point to the 18 gauge rating?

Statement from seller on cables: Note these are 16 Guage Class Cables / Positive Wires are 16 guage / the 2x Negative Wires are 18 Guage.


texts:
To begin with,I am not designig an oscilloscope but am curious about how certain parameters are determined. My questions might sound very trivial but I would be grateful if someone could answer them convincingly.

I have seen oscilloscopes with say a 50 MHz bandwidth but 1 GS/s sampling. My question is, why do I need such a high sampling rate when the signal is restricted to 50 MHz? I read on an oscilloscope manufacturers website that a good rule of thumb is that to visualize a signal of say X MHz, you should have an oscilloscope between 4X to 6X MHz bandwidth. What is the justification for such high sampling rates then (When compared to the bandwidth)?

I have also seen probes with a bandwidth limitation. Is it a must to use these if the scope has a filter as well? On the other hand, can there be an oscilloscope which leaves the filtering entirely to the probe and has no filtering of its own?


texts: Home automation: why is wireless more popular than data over power line?

texts:
This is a question for discussion... I have recently started looking in to home automation and "smart devices" and see a clear tendency for everything to run on WiFi, with some exceptions of bluetooth, Zigbee and Z-wave.

But why data transfer via power line (PLC) is not a thing, really? It sounds much cleaner without all that RF noise?

I've looked in to power line modem chips and they are quite expensive ($3 and up), compared to ESP chipset. Is this the reason?

Multiple PLC devices also need a single interface ("hub") to WiFi. Is this another reason?

From comments it looks like main issue with power line communication is noise. An example of X-10 was mentioned and I have quickly found this product, which has been discontinued: http://www.csi3.com/homevis2.htm
There's a PDF explaining all sorts of problems the X-10 protocol suffers from:
http://www.csi3.com/app_x10.pdf

Basically X-10 will be killed by any equipment that injects noise close to zero-cross, for example brushed motors.

From quick search it looks like X-10 is a very primitive protocol and has no error correction or other more modern means of noise immunity or bandwidth sharing.

There are LAN modules out there, sold even today (and not that cheap), but these were outperformed by WiFi some time ago, so WiFi is an obvious choice for high speed connection.
However low-speed communication potential seems to be forgotten... If only there was a way to combine robustness of LAN-over-AC and low price at low speed...


texts: What are the pros and cons of having higher/lower dBi and dBm?

texts:
I have a UHF reader with integrated 7dBi and 9-30dBm output power.

Can you explain to me what do these 7dBi and 9-30dBm mean, in a way an ordinary people (like me, who don't really have knowledge in network) could understand. As far as I researched, there is no absolute formula to get the distance of a dBi, theoretically speaking dBi won't affect the range of an antenna? but I also found out that higher dBi means higher gain and more directional. What does it mean?

In other words. What could possibly the pros and cons of having a higher/lower dBi and dBm?

If possible, can you give a situational explanation.

Thanks in advance.


texts:
o I have tried tackling this problem, but I cant seem to get anywhere. I dont know if I am making things too complex. I came up with this state diagram and state table. But I dont know if this is too complex. I dont even know how to implement it from my state table. I described my issue below.

Okay I have a system which consists of a spinning circular disk and stationary probes A (at 12 o’clock on the disk frame) and B (at 3 o’clock on the disk frame). One half of the disk is black and causes a either probe to read 1 when the black portion of the disk passes underneath it. The other half of the disk is white and causes a probe to register 0. The system has three synchronous inputs (A, B and ENABLE) and the two moore outputs (VALID and DIRECTION). I need to figure out if the disc is spinning clockwise or counterclockwise.

When the disk is spinning at full speed ENABLE is asserted (1). While enabled, the clock frequency will be high enough to guarantee that the disk is sampled 8 times per rotation. Otherwise (when the disk is stopped or changing direction), the external system holds ENABLE low (0).
The value of the DIRECTION should be low (0) if the direction of the spin is counterclockwise. The value of DIRECTION should be high (1) if the direction of spin is clockwise. The value of DIRECTION output is ignored (and thus can be treated as don’t care) until valid is asserted.
Whenever ENABLE is low or when ENABLE is high and the DIRECTION is not yet valid, the output VALID is held low (0). Once the direction of the spin is determined (and the value of direction set accordingly) VALID should be asserted.
Once the VALID is asserted, the outputs should be held stable until ENABLE goes low.


texts: How to identify areas of a FPGA design that use the most resources and area?

texts:
I am working on a large FPGA design, and I am very close to the resource limits of the FPGA that I am currently using, the Xilinx LX16 in the CSG225 package.

The design is also almost complete, however at the moment it will no longer fit in the FPGA. I can turn off parts to get it to fit, however I need to reduce the resource usage in order to complete the design and have it meet timing and size requirements.

I would like to know if there are any tools our reports that can help me identify which parts of my design are consuming the most resources. My design is not partitioned, and is split over about a dozen or more VHDL modules.

Xilinx timing reports are fantastic, but now I need to know where I can get my best bang-for-buck in terms of space saving.

I also have a hard time telling which type of resources I'm running out of, or what effects those resources.

Another annoyance is that as the design gets larger, components that used to meet timing are starting to fail because their placement is no longer as ideal.

Currently, I use the Post-Place and Route Static timing reports, and I use SmartXplorer. I'm using design strategies to optimize for timing.

After turning off part of my design to get it to fit, here are some of the results:

slice register utilization: 42%
slice LUT utilization: 96%
number of fully used LUT-FF pairs: 38%
Does this mean I'm light on registers, but heavy on gate usage?

Are there tools to help developers optimize for area, or at least give them more insight into their code?

Update:
After looking at the Module Level Utilization, I found out that I had small glue async fifos all over the place that take up about 30% of the total LUTs. I am using them as cross-clock-domain glue for high speed buses. I should be able eliminate these, since the clocks are tightly related. (120 MHz input, produces 100 MHz and 200 MHz through DCMs)


texts: Opamp: determine the transfer function with negative RC feedback

texts:
I would like to find the transfer function of the above ideal opamp circuit. One of my approach was neglecting the effect of R2(assuming the voltages on the both side of R2 are the same) and applying node method to above node but the result is seem complex and wrong to me.

Since I haven't got the answer, I want to be sure if my approach is right or what would be the correct approach.

simulate this circuit – Schematic created using CircuitLab


texts: Make powered USB Cable for External hard-drive

texts: We purchased a 2.5" Seagate external hard drive. For power and data transfer it has a USB 3.0 cable, like this  Amazon USB Cable. It works great on the USB 3.0 ports on the PC but the Smart TV does not deliver enough power through the USB port to work. I have tried it with a USB extension cable like this Powered USB Extender with an extra plug dedicated to power connected to a phone charger and it worked.  I need that cable else were have the parts so i  was looking to make a similar cable out of an old USB extension cable and a old phone charger. Would I be able to connect both the power coming directly from the port and the charger together or would I only be able to connect the power to the charger? I ask this because I also want to use the cable with other devices that do not require extra power.


texts: Is there a sure-fire way to determine if an MCU is fried?

texts: I have a PIC24FJ32GA002.  I think I killed by accidently exposing it to 5V instead of the rated 3.3V. It was very quick, less than half a second. I am not able to get it to communicate with my programmer, but I didn't test it beforehand, so I am not sure if my circuit is wrong or I have wired something up incorrectly. Unfortunately I can't get any more MCUs any time soon. Is there any way to determine if the MCU is truly dead?


texts:
The circuit purpose is to control square signal frequency from 100Hz to 1kHz (generated by MCU GPIO) and be able to control amplitude from 100mV to 2.3V. It is like a very simple signal generator. The goal is to keep edges <100ns.
Switch is SN74LVC2G53. The schematic:

Problem: I get ringing on rising edge (ringing Frequency 3MHz), and on falling edge going negative about -600mV.

Layout(i know it's bad, but i had no choice at this time. I will redesign the PCB later ):

How can i reduce ringing on falling edge?


texts: What was used as paint on insulation/conformal coating in the 1950s?

texts:
I'm restoring a multimeter from the 1950s and I was wondering what was used as paint-on insulation/conformal coating. It's the yellow/brownish stuff smeared on the screws and leads in the photo.
I suspect it is shellac, was this commonly used in the 1950s in electronics?
It is not greasy and quite hard. It will melt a bit with a soldering iron.


texts: Identifying power supplies / DC adapters

texts:
I have a box of miscellaneous power supplies / AC adapters / transformers / "bricks" which have no information on them about what they are for. I am trying to match them up to the devices they belong with, including computer items, drives, cameras, and who-knows-what else. Some of the devices may have already been discarded.

Sometimes I have been successful typing the model numbers into Google, but usually I just get nothing,  or maybe a list of places to BUY the adapter. With some, I am told they are for a camera, for example, and that narrows down my search.

Does anyone have tips for identifying them? Wouldn't it be nice if there was a website with some sort of cross-matched list for these things?

Examples:

Sino-American Model A30980 AC Adapter Class 2 Transformer;
Ambico 45-8820 Class 2 Transformer Model 35 - 7.5 - 300C;
AC Adapter (No Brand) Class 2 Transformer Model No. DBU120020


texts: How to represent a human body with other materials?

texts:
I'm not sure how to phrase this question, but maybe some of you have done research with this...

I am doing some measurements on wireless body area networks, which involves putting sensors on human bodies and transmitting. Now, I can put them on living humans, but if I could somehow "model" a body instead, it would provide more repeatable data. Also normal humans breathe.

Anyway, I think I saw some paper mention certain material properties in simulation, and I might attempt to find materials with those properties (and just wrap a bucket or something). But if anyone has any ideas that would be much appreciated...


texts:
I have an I2C device that I would like to interface with Android. It seems that the easiest way would be to use a microcontroller compatible with Accessory Development Kit. But these kits and their microcontrollers are huge in size and I am looking for a solution which will work with a micro-USB and will fit in a form factor of 1 x 0.5 x 0.5 inch.

FT311 seems to be another option but it looks like an overkill for my application.

Is there any other option that I can use. I was hoping for something small like TI's MSP430 to work with Android.


texts: Accelerated life test of rechargeable batteries

texts:
How can I perform accelerated life test of rechargeable batteries?
How can I compare 2 different brands of batteries in accelerated life test?


texts: Do Quadrature and Bubba oscillators count as phase-shift oscillators?

texts:
I need this information for my school report. Do these oscillators count as phase-shift? I found some references here at the Texas Instruments website, but I'm not quite sure:
https://www.ti.com/lit/an/sloa060/sloa060.pdf
http://www.ti.com/lit/an/slyt164/slyt164.pdf

"The Bubba oscillator (Figure 9) is another phase-shift oscillator"
"The quadrature oscillator is another type of phase-shift oscillator"


texts: No output for N-Channel MOSFET on PWM on STM32F0

texts:
I am using dual N-Channel MOSFET FS8205A, following is a screenshot from its datasheet.

and the following is the schematic I am using in my project.

The Gate is also pulled down to the ground with a 10K resistor, but the problem is, I am not getting any output, I have even replaced the microcontroller, and the same issue, I think the problem is somewhere is in the design of MOSFET circuit that I can not figure out, any help would be appreciated.


texts:
i would like to know what cores at physical level are in a cpu. some mix of logic gates make a head that's called a core is it?.so one core how does it appear to be in physical level.!
PLease am new to this field.Any kind of help i would be obliged to receive.
Sorry for my poor technical grammar.

Regards,
Snook


texts: When I compile my schematic, I get some errors in the compile window. When I double click them it zooms in on them and highlights them with a mask. How do I get rid of that mask?


texts:
I am using a Phillips SAA3010 IR transmitter IC to send a modulated IR signal. The IC has two types of inputs:

Z0---Z3
X0---X7

And one type of output:

DR0---DR7

Each legal operation corresponds to a wired connection of DR-Z and DR-X pin. The device is designed to be interfaced with a keypad on a remote control, per the datasheet description:

  Every connection of one X-input and one DR-output will be recognized as a legal key operation and will cause the device to generate the corresponding code. The same applies to every connection of one Z-input to one DR-output with the provison that SSM must be LOW. When SSM is HIGH a wired connection must exist between a Z-input and a DR-output. If no connection is present the system number will not be generated.

The desired switch arrangement is described in this figure from the datasheet:

However, I want to do the wired connection electronically, so as to make the switch programmable via an Arduino.  I have to obtain 64 such legal key connections. I have tried using a MUX/DEMUX IC but as they use gates, no wired physical connection exists. I believe that this will not work unless there is a wired physical connection.  The datasheet certainly assumes that a physical keypad will be used.

How can I do this using the minimum possible space?  My physical limitations are that the device has to be about the size of a typical mobile phone, which includes the Arduino UNO board.


texts: How do I easily flip odd and even pins between a Raspberry Pi and Pi hat?

texts:
My group built a custom hat for a Pi but when we integrated it we discovered a problem with our implementation.

Our even and odd pins were reversed. On the Pi, the headers are

------------
2  4  6  ...
1  3  5  ...
------------

But our board has the pins

------------
1  3  5  ...
2  4  6  ...
------------

Our 40-pin headers are surface-mounted on the bottom, so we cannot easily turn it around or put it underneath. We can connect a bunch of jumper wires and the circuit works by flipping the order of pins, but it'd be great if there was an easier workaround.

Is there some kind of thing we could get to do the reversal, or should we just do a revision on the boards?


texts: Understanding generator wear and rotor electrical measurements

texts:
I have a generator that I am attempting to fix, and I am getting readings that are out of spec on the rotor brushes. Per some instructional videos I found, I should be measuring 5V AC on the rotor brushes. I am measuring 65-70V AC. The video I was watching said that a high voltage reading (Assuming the brushes were good) indicated a bad rotor.

How can a rotor go bad (besides bearings and I'm sure I would notice other physical issues with the operation - the motor runs fine) and what are the electrical properties that cause it the voltage to read so much higher than nominal?

Edit: Per the question in the comments, this is a Duromax xp10000e (10000W peak) generator. The video I mentioned can be viewed here. I intentionally did not include that information originally because I was attempting to better understand the theory and principles at work, not just information related to my specific generator.


texts:
I was looking at this wallace tree diagram for an 8x8 multiplier:

and I'm confused about why the pairs of two (and the one pair of 3) are not added together in the initial reduction layer.  My understanding is that all pairs of three should be sent into a full adder and all pairs of two should be sent into a half adder.  Is this diagram incorrect, or is my understanding incorrect?


texts: Can I reverse bias the base-emitter of a BJT transistor?

texts: In this example, transistor Q1 (a PNP one) has +12V in emitter and +15V in the base, the Vbe is +3, and being a PNP one, it is reverse biased with 3V. It is ok to bias like this ? I mean the transistor won't break ? How much reverse bias can withstand ? I have not seen this information in datasheet.


texts: Query on writing KVL equation for an RL circuit

texts:
Say I have the inductor in the following circuit with certain current already in the circuit flowing in the specified direction:

simulate this circuit – Schematic created using CircuitLab

If I had to write KVL for this circuit, would I write $$ L{di}/{dt}-iR=0$$ $$or$$ $$ L{di}/{dt}+iR=0$$

I always get super confused about what sign to take for the induction. I know by intuition(by the fact that the solution for the differential equation of (1) would be an exponent with positive power which is absurd) that it should be (2), but I always get stuck on that sign.


texts: Figuring out transistor function in schematic

texts:
I know some digital logic. Here is a simple Full adder schematic. It is easy to understand the digital part but i don't understand the logic of adding transistor on the sum output? What is the purpose of adding this transistor? Why only at the sum output? Why not the carry output as well.

Any recommendations on how to nail down more sophisticated schematics?


texts:
I want to use a microUSB connector on a board I'm designing.
The dimensions of the connector that I'm using is in this Datasheet.

To make a lib I'm using Altium, after setting the dimensions here's how the part looks.

The problem is that I've checked that my dimensions do match the datasheet, however only on the Top layer (red).
When I check the Top Solder layer the pads are connected to each other.

How will this board look if I get it manufactured?
Is the Top layer (red) the footprint, or is the Top Solder layer (purple) the footprint?


texts: How do batteries connected in parallel give more current than batteries connected in series?

texts:
Let's say we have three 1V batteries and we're connecting them to a 1Ω resistor. Connected in series, the voltage is 3V and since the resistance is 1Ω, that means that from Ohm's law, the current should be 3A right? And then when we connect them in parallel, the voltage is 1V and the resistance is 1Ω so the current is 1A right?

So do I misunderstand the statement that batteries connected in parallel supply more current or do I misunderstand Ohm's law?


texts:
What is the recommended and maximum current sourcing and sinking capability on the DS1302?

Is this what's given by "Active Supply Current" in the spec?


texts:
So I've searched for days for information about the 74HC244 line driver. As always, the Datasheet provides raw and not very good information about the actual component :) (I mean, it gives us the temperatures, but not how the actual component works...)
Any way, there is very little information about Line Drivers in general. So, how do thy actually works? And how the 74244 can act as a line driver? All I see in the inner structure is enables and input to outpuut wires.
EDIT
I'm using the 74244 to connect between my Altera (FPGA) and a servo motor. I think that in order to reduce the current that the FPGA suplies to the servo, I need to put the 74244 in between them, thus reducing the "effort" from the Altera. Is that necessary? Or the Altera can provide a good current flow to the servo without damaging it's abilities?


texts: 5V 1A from 24VAC transformer with grounded secondary

texts:
I built a power supply for a micro-controller board that requires 5VDC and peak of 1A (typically sits at 500mA). The power supply has an input of 24VAC. I used a bridge rectifier and an LM2575-5 switching regulator to get 5V 1A. All good, worked well.

Problem is I've now found out that the 24VAC input transformer must to shared with some external devices in the same system (controls equipment), and they use a 24VAC transformer with the secondary neutral grounded. This made my bridge rectifier go bang!

I don't want to have to use a separate 24VAC transformer, so I was thinking of using a half-wave rectifier. I've found that the LM2575 regulator will accept about 8V to 40V input and is about 75% efficient. To overcome the ripple from the half-wave rectifier, the smoothing capacitor would need to be huge.

Surely there's a better way to do this! Maybe a half-wave rectifier isn't the right way to go about this? I'd really appreciate some advice and suggestions.

Disclaimer: I'm not an EE, just a tinkerer... In case that isn't already obvious ;-)

Edit: Here's a circuit diagram.

simulate this circuit – Schematic created using CircuitLab


texts: How to tune PID for a Y(t) = k*X(t) system?

texts:
Could I have your opinions on PID type selection?

System description

Here comes a very simple system: Output(t) = \$ k * (Input(t) + systemVariable(t)) \$. \$k\$ is constant and \$systemVariable(t)\$ is a system constant which may change according to time.
The goal of the whole system is to maintain system output at \$0\$. It has to be as close to zero as possible. The controller has to compensate the \$systemVariable\$.
The change (\$ systemVariable\$ ) is modeled by a very slow ramp.

Controller description

The controller's input is the output of the system. However, the measurements are always noisy, and I modeled Band-Limited White Noise into the measurements.
After PID controller, the output goes into an integrator, since the PID controller always calculates the "change" of the plant input.

Questions

My original thoughts: Add a PID controller with P=1/k is enough. Since every time the controller gets an error \$e\$, it can be calculated back that the compensation on controller output shall be \$e/k\$. However, Matlab auto-tuning always give me a PID. Why is that?
What is the relation between P of PID and measurement noises? If P is large, the system will tend to be rambling largely, due to the noises. If P is small, the system will tend not to converge to the correct value or very slow. How to make the trade-offs? Or how to prevent system from rambling largely and get quick system responses?

Thanks a lot!


texts: For this circuit, I am trying to find the equivalent Thevenin impedance by disabling the sources and calculating the resistance between points A and B. What happens after the voltage source is replaced with a wire? I have the current source being an open circuit so the capacitor and 2k resistor are in series, but does the wire contributed from the voltage source short this combination? If so, would the resulting equivalent resistance just be the two kilo ohms in the top left? Thanks for any help


texts: Is it possible to use PIC10Fxx internal flash to store data between deep sleep?

texts:
I want to store a single bit with rare rewrite. It's possible for STM32 without EEPROM, but how about PIC microcontroller?
And is there examples with configuration and code?


texts: Time required for toner transfer vs UV light for manual PCB fabrication

texts: Me and my group mates is currently on our planning stage of our design project in the fourth year of our program. We are going to make a direct sketch to PCB printer using CNC. I just want to ask, based on your personal experiences, how much time it takes for you to create a PCB using toner transfer method compared to UV light method? This will help us to know the efficiency of our project compared to manual processes. Thanks!


texts: Problem I2C reading RA8875 using TM4C123

texts:
I have been working with I2C protocol to create some code for the RA8875 (see for I2C from page 67) using a Tiva board (TM4C123, I2C chapter from page 997), and I was able to paint in the display or writing text, but I am struggling when I want to read a value from a register.

For what I could read about I2C, I understand that the process should be as it follows:

Send a write command, specifying the adress of the register
Send a read command, so the board reads the data from the register

The code I use for I2C read is the following:

unsigned char lcd_read(unsigned char data,short I2C)
{
    unsigned char response;
    switch(I2C)
    {
        case I2C0:
        {
            while(I2C0_MCS_R&I2C_MCS_BUSBSY);
            I2C0_MSA_R |=0x0E;  //Specify the slave address of the touch screen and that the next operation is a write command
            I2C0_MDR_R=data;    // Register address
            I2C0_MCS_R=0x03;    // (START, RUN)
            if(I2C0_MCS_R&I2C_MCS_ERROR)    //Check the ERROR bit in the I2CMCS register to confirm the transmit was acknowledged.
            {

            }
            I2C0_MSA_R |=0x0F;  //Specify the slave address of the touch screen and that the next operation is a read
            I2C0_MCS_R=0x07;    // (STOP, START, RUN)
            while(I2C0_MCS_R&I2C_MCS_BUSBSY);   //Wait until the transmiI2Con completes by polling the I2CMCS register's BUSBstart_Y bit until it has been cleared.
            response = I2C0_MDR_R&0xFF;
            if(I2C0_MCS_R&I2C_MCS_ERROR)    //Check the ERROR bit in the I2CMCS register to confirm the transmit was acknowledged.
            {

            }
            break;
        }
    }
    return response;
}

Another thing that happened to me is that what I can see in the registers (I use Code Composer Studio for coding and debugging) do not correspond to the data obtained using a protocol analyzer (i.e. content of register I2C_MDR). Probably this could be a separate question but, what can be the reason of it?

Edit: The following images show how data is transmitted. The read data should be 0x81 instead of 0x00:

I2C write to register:

I2C read from register using the code above:

Thanks for your help.


texts: How to calculate the voltage across the load of this circuit

texts:
I have this rechargeable night lamp which I built it using the circuit which I got it over the internet.There is no problem with the night lamp but I just wanted study the working of the circuit but I am not able to calculate the parameter like voltage.
can Anyone help me out with this.

i just want to know how to calculate the voltage 'V' in the cicruit.


texts: ATmega48PB: wdt in interrupt mode still reset the MCU

texts:
I read the datasheet and this question, but there's still something wrong here.
Here my wdt init code:
cli();
MCUSR &= ~_BV(WDRF);
WDTCSR |= _BV(WDCE) | _BV(WDE);
WDTCSR = _BV(WDP2) | _BV(WDP1) | _BV(WDP0);
WDTCSR |= _BV(WDIF);
WDTCSR |= _BV(WDIE);

Leaving fire the wdt I expect it does nothing but set the WDIF bit, instead it resets the MCU.
Is there something wrong in my approach?


texts:
I'm going through some addressing schemes with CAN bus. I came across this post: Most efficient way to handle addressing / termination in a daisy-chained CAN bus?
There's a solution explained called EmCAN. The author says:

EmCan solves the node address problem without requiring special
hardware. For details, see the EmCan spec, but basically, each node
has a globally unique 7 byte ID. Each node periodically requests a bus
address and sends this ID. The collision detection mechanism will
guarantee that the bus master sees only one of these requests even if
multiple nodes send a address request at the same time. The bus master
sends a address assignment message that includes the 7 byte ID and the
assigned address, so at most one single node is assigned a new address
at a time.

So I'm thinking of this approach:
Until an address is assigned, nodes can only act upon broadcast messages from the bus master, and can only send requests for a address.

There's an unique serial number of 8 bytes, derived from the unique chip identifier of the STM32.
A node ID which is a number between 1 and 127

At first boots up, the node gets a default address 0. It sends its unique 8-byte serial number to master (in the data frame), which then assigns the node a shorter node ID between 1 and 127. As of that point, the node uses only the node ID assigned for communication.
So the big question: what if two nodes with no address assigned send the same address request with the same node Id of zero at boot up? This would cause a conflict no addressed by the CAN protocol.


texts: Connecting multiple input devices to 8 channel relay board

texts:
I have an 8 channel relay board (here's a link to the actual product (http://smile.amazon.com/dp/B00KT0E1RY/ref=sr_ph?ie=UTF8&qid=1463753455&sr=1&keywords=smakn+8+channel).

I understand how to hook everything up so that the inputs control the relays correctly, however I have one concern on my inputs.

I realize that this board may be designed more for arduino projects, but I have three different input devices (Axis Door Controller a1001) that have two outputs each of 12v.  When one of the six outputs applies 12v, the corresponding relay activates the controlled device (in this case, electric door strikes).

My question: I noticed that on the input side of the relay board, there is only one negative terminal and 8 signal terminals.  My thought is that the positive of the each input will need to be attached to the a signal port and the negative would get attached to the common negative.  Will this be a problem with having all of the inputs negatives attached together?  I know enough to be dangerous, but don't want to have issues if 12v from one input device is somehow interfering with the other devices because the negatives are all connected?  I thought that it could be a good idea to have one relay board per input device (a1001) in case this might be a problem.

Thank you!


texts: Set multiple pins to different GPIO ports

texts:
I am using an STM32F4 discovery board and I have the following array v

typedef struct pin_map_dummy {
     GPIO_TypeDef* GPIO_Port;
     uint16_t GPIO_Pin;
} pin_map_t;
...
vector_pin_t v={{GPIOD,GPIO_Pin_0},{GPIOD,GPIO_Pin_1},{GPIOD,GPIO_Pin_2},
{GPIOD,GPIO_Pin_3} , {GPIOD,GPIO_Pin_4}, {GPIOD,GPIO_Pin_5}, {GPIOD,GPIO_Pin_6}, {GPIOD,GPIO_Pin_7}};

I'm passing the array to the initialization function but I'm trying to figure out if it's possible to set each Pin to a different GPIO port, in the array v all pins are located in PORTD but what if one pin happens to be in PORTA

This is the GPIO init function:

 void init_library(vector_pin_t pines)
    {

        GPIO_InitTypeDef puerto;
        RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);

        puerto.GPIO_Pin   = pines[0].GPIO_Pin | pines[1].GPIO_Pin | pines[2].GPIO_Pin | pines[3].GPIO_Pin
                          | pines[4].GPIO_Pin | pines[5].GPIO_Pin | pines[6].GPIO_Pin | pines[7].GPIO_Pin ; //All pins
        puerto.GPIO_Mode  = GPIO_Mode_OUT;
        puerto.GPIO_OType = GPIO_OType_PP;
        puerto.GPIO_Speed = GPIO_Speed_100MHz;
        puerto.GPIO_PuPd  = GPIO_PuPd_NOPULL;

    GPIO_Init(pines[0].GPIO_Port, &puerto);

}


texts:
I am trying to understand something about Lenz law.
First, let me show an example of what I do understand.

In this image, I understand

a) As the loop moves closer to the current the field increases.  So
therefore the current must go in the opposite direction, thus counter
clockwise.
b) the loop moves farther away, the field decreases, so
the current moves clockwise around the loop.
c) the field doesn't change, so there is no current change.
d) the current increases, which increases the field, and that has to be
negated, so counter clockwise.

Those are the correct answers.

However, when looking at another example, I am having some troubles.

With this I understand b) and c).

b) The current is constant, no change.
c) Again, there current is constant, and the loop is not moving in a way to change the field.

But for a) and d).  I don't understand.

a) is clockwise, so this is acting a decrease.
d) is counter clockwise, so this is acting as an increase.

But I don't understand how the sinusoidal are interacting differently.
Can someone please explain how the sin and cos functions act on the loop?

Thanks!


texts: How to safely split a power supply into two?

texts:
I have 6AA batteries connected to this UBEC, giving me 5V 5A. Now I have an Arduino Mega and this SIM900 GPRS shield which I need to power. As I have a steady 5V I can power the Arduino through the 5V pin, however the SIM900 shield requires a lot of current and therefore cannot be powered via the Arduino. In this case I need to power them from the same power source, but powering them separately.

Is there a safe way to power them something like the image below? As the two shields are stacked on top of each other, does this cause an issue (or does it just give them both a common ground?)?


texts:
I got a new camera, a Pentax KX, and am enjoying the movie mode, which not surprisingly eats batteries at a rate of about 1 alkaline AA per minute!

Can you point to any examples on the web of people building a circuit to patch some large rechargeable battery (say my laptops Li-Ion) to an AA battery compartment?


texts:
I have a USB controlled device (Razer DeathAdder Chroma) that has an RGB LED on it and I would like to use that LED to control a 5050 RGB LED strip about a meter in length. Both the "input" LED and the strip are common anode with the "input" LED's + pin at just over 3V and the strip's at just over 12V.
I planned on following the adafruit RGB LED Strip tutorial with the gate on the MOSFETs being connected to the "input" LED. The problem I run into is which ground do I use? The ground from the 12V supply that's powering the strip or the ground pin on the USB device.
Pictures of the LED and a segement of the LED strip.

Any advice would be greatly appreciated and thank you in advance!


texts: I would like to hook up a PIR motion sensor like the one found here with a standard electric air mattress pump like the one found here. I'm pretty sure this is basic electronics stuff but I have zero experience. Any ideas on how to do it and what materials I might need? Any help would be greatly appreciated!


texts: BJT Circuits at DC, base current calculation

texts: I'm trying to walk through the example calculations in the attached example however I cant understand how the author gets the expression for the first step in the process. I tried making up the expression however I get stuck when equating the current. I have attached an image of the example(in Sedra&Smith 6th or 7th edition). I have also attached an image that shows my approach to step one.


texts:
I have been looking at B57238S0100M0** NTC which is rated with

R25 = 10R
I_max = 5A
R_min = 0.16R

I already inspected the resistance vs temperature curve and it appears to be straight forward.
However, the resistance vs current graph is rather confusing due to its discontinuity. Is it safe to assume that the resistance of 10R will remain unchanged up to 1.5A in case of B57238S0100M0** variant?


texts: The equivalent resistance between terminals A and B?

texts:
Resistors R2,R3,R4 are connected in series.  I'm not sure how to find the equivalent resistance of between terminals A and B, because of the short circuit.  However, I suspect the answer is R1+R4 because of the short circuit.  I am confused about this, can someone help me?  Thanks!

EDIT: Thanks for pointing that out.  My drawing is indeed incorrect.  Lets say the resistor R4 which is connected in series to R2, R3 will now be called R5


texts: What's the purpose of the diode in this selectable supply voltage circuit part

texts:
I'm looking at the power supply part of the schematic of SparkFun's Pro Micro Arduino board, which has a jumper to enable or disable a voltage regulator to select between running the board at 3.3V or 5V:

I have two questions about D2:

What is its function in the circuit? Where can I read up on the motivation for adding it to the circuit? What would happen without it, and is it needed if I always want to run the board at 3.3V, i.e. if I omit the jumper?
What kind of diode would I use if I build this board myself?


texts: I've been struggling with this software to find male pin header connectors but I could not find it even on the online database, has anyone an idea ? Thanks!


texts: Resistors - proper SMD package for newbie

texts:
I will be designing an Arduino shield in KiCAD.
This will be my first project in KiCAD.
Considering I am a newbie in PCB design and I will be performing the soldering, what is the correct package size to pick?
The ones offered by the website I will be buying from are:

0402
1206
2512
603
805


texts: Simple number counter - PIC16F877A microcontroller problem

texts:
I am trying to make a simple counter using pic16f877a. I want to count each time a push button is pressed, that is taking one press as one count, regardless of how long the button is pressed.

The software I am using are MPLAB X IDE and XC8 compiler. I use Pickit 3.5.  I use an indicator LED to see whether the code is working.

The thing is, I have barely achieved what I needed, but the code seems unstable. It works sometimes but not in others. For example, let say the code worked now and LED blinked correctly when one of two connected buttons pushed. Then if I "make" and "download" the program again without any edits to the code in MPLAB X IDE, the LED won't blink. While writing this I tested several times just by making and downloading using MPLAB IDE, without changing anything hardware or code, and then it worked. The only thing that was changed in those situations was TIME. I suspect this has something to do with resetting of the PIC although I have no idea. Never worked on 2 consecutive "make and download"s.

Code:

#define _XTAL_FREQ 20000000
#include <xc.h>
#include <stdio.h>
#include <stdlib.h>
#include <pic16f877a.h>
// CONFIG
#pragma config FOSC = HS
#pragma config WDTE = OFF
#pragma config PWRTE = OFF
#pragma config BOREN = OFF
#pragma config LVP = OFF
#pragma config CPD = OFF
#pragma config WRT = OFF
#pragma config CP = OFF

void main(void) {
    TRISB=0;//LED connected to RB0
    TRISD=1;//two push buttons connected to RD0(buttonRight) and RD1(buttonLeft)

    while(1)
    {
        if (PORTDbits.RD0==0)//if buttonRight is pressed,
        {
            __delay_ms(5);//debouncing.
            if (PORTDbits.RD0==0)//if buttonRight is still pressed,
            {
                PORTBbits.RB0=1;
                __delay_ms(500);
                PORTBbits.RB0=0;
                __delay_ms(500);

                /*to take as one press no matter for how long it is pressed.*/
                while(PORTDbits.RD0==0);
            }
        }

        else if (PORTDbits.RD1==0)//if buttonLeft is pressed,
        {
            __delay_ms(5);//debouncing.
            if (PORTDbits.RD1==0)//if buttonLeft is still pressed,
            {
                PORTBbits.RB0=1;
                __delay_ms(100);
                PORTBbits.RB0=0;
                __delay_ms(100);

                /*to take as one press no matter for how long it is pressed.*/
                while(PORTDbits.RD1==0);
            }
        }
    }
}


texts: Conceptually, what is the Message frequencies affect on the FM signals rest frequency

texts:
Context: Frequency modulation via a Voltage Controlled Oscillator (VCO)

If I take a message signal of frequency \$F_{mes}\$ and use it to generate a FM signal with a VCO, which has a rest frequency of \$F_r\$ and a deviation frequency of \$F_d\$, what is the relationship between the rest frequency \$F_r\$ and the message frequency \$F_{mes}\$?

Does the frequency modulation follow: $$F_{FM} =  (F_{mes}\times F_r)+F_d$$
Or am I completely off?

My reasoning is that the change in the magnitude of the message signal amplitude is proportional to the change in the deviation frequency. However, increasing the frequency of the message signal will increase the frequency of the deviation frequency being changed, therefore it alters the base rest frequency to a new rest frequency value that the deviation frequency can then move away from due to different message signal amplitude values being input.


texts: Difference between \$r_d\$ and \$r_D\$ in diodes?

texts:
I'd like to know what's the difference between \$r_d\$ and \$r_D\$ when regarding diodes.

I know that \$r_d\$ means dynamic resistance, but I'm not sure what \$r_D\$ means, and how it differs from the latter.


texts: 32F746GDISCO Stackup and Ethernet Impedance

texts:
I have an example board with PCB about the ethernet application.
I noticed a mismatch between stack up and ethernet lines, or something else I don't know.
Ethernet Lines are drawn with 0.125mm and its gap is set to 0.175mm.
However, when I examine the layer stack up, the line impedance becomes 124 ohms.
Am I doing something wrong?
By the way, the lines were drawn at the top and bottom layers.


texts: Can I use a ULN2003A IC as many transistor switches?

texts:
I want to make home automation using Arduino. Instead of relay modules, I prepare my own relay module using relays and transistor switches, in between the Arduino and relays.
I want to make many transistor switches. Instead I planned to use IC like ULN2003A which has 7 darlington arrays that I can use as switches. They also have flyback diodes to protect from sudden spikes. (Also cheaper compared to 7 transistor switches and diodes.)
Is it a good idea to use it? Or is there a better way to solve my problem?
Additional info:
I need to turn on/off 220V loads using 5V DC relays which are activated by a PNP transistor switch, whose base current is provided by the output of an Arduino and collector-emitter has a separate power source to activate the relays. If I want to operate many appliances, many such transistor switches are needed. Hence I searched for a simple solution and found an IC which can act as multiple transistor switches (ULN2003A).
Is it ideal to use that in my circuit, considering power losses and other factors?


texts: Orientation of "bipolar" capacitors on PCB

texts:
I've come across a video on a popular and well-respected electronics channel on Youtube where they say that even bipolar capacitors have a preferred orientation in a circuit that minimizes hum and interference etc.
They describe an oscilloscope based method to determine that orientation of the capacitor that is easy enough to implement.

I wonder, however, once that capacitor polarity is determined, how to find out which way to put the cap into the PCB .. without knowing too much about the circuit or the schematics. Is there a multimeter or oscilloscope based measurement that could be carried out? The capacitor is supposed to go into the board so that one side goes in direction of lower impedance and the other in direction of higher impedance. Positions of electrolytic caps are labeled + and -, but PCBs are not typically labeled that way for bipolar caps, and schematics of circuits are not always available.

I understand that most people would consider this overkill on most circuits, but I'm interested if it's technically possible to carry out the corresponding measurement on the PCB side of things. Thanks!


texts: Not able to levitate magnet for magnetic levitation project

texts:
I am following a hackster project on magnetic levitation here - https://www.hackster.io/jsirgado/magnet-levitation-with-arduino-eeeee4

However, I have followed everything but still, it's not working.

Here are changes to the circuit I made:

The electromagnet which I am using is that of 5V instead of 12V
The transducer which I am using is ss8050 instead of TIP120
Hall sensor is tapped just at the bottom of the electromagnet

Electromagnet link - https://shop.edwinrobotics.com/widgets/1568-5v-electromagnet-25-kg-holding-force-p4020.html

Update:-

The best I can do is to make the magnet jump up and down fast but it never levitates. Have tried changing PID setting from the project as aggressive and mild but still didn't achieve the final result.

I need advice from an expert to tell me what I am doing wrong here. All components are in good condition and 5v electromagnet is strong enough.

So what am I missing here?


texts: Programming several AVRs with one ISP: which line to break?

texts:
Let's suppose that I have two AVRs connected to one ISP connector.

To programm only one MCU in this configuration I neet to break one (or mayby several) lines goes to the MCU I don't want to be programmed in this moment.

The first line comes to mind is VCC, which would be great as I'd save power. But as we know - power will go through digital lines wich have protection diodes to VCC and GND.

So I'd choose RESET line. Any other ideas?


texts: Level shifting in OPAMP and HE100T01 interfacing problem

texts:
Hi,

I want to measure current of 0-50A. For that, in my application I am using HE100T01 hall effect sensor which can measure current from -100A to +100A(depending on the direction of flow it gives -ve and +ve values).
The Hall effect sensor gives a current output of -50mA to +50mA. Since my micro controller ADC can't measure negative voltage, I tried level shifting the sensor output to positive region using the circuit which is attached. But the negative voltage is not properly clamping to the +2.5V  offset. Can anyone please help me to identify the problem and also give any alternate circuitry to convert the sensor output which can be measured using a micro controller ADC?

Please find the datasheet for the Hall effect sensor and attached schematic.
http://www.electrohms.com/data_pdf/2_1_HE100T01-05.pdf

Looking forward for earlier responses.

Regards,
Vishnu


texts:
I have an iphone 4 that no longer works.  I know that selling it is always an option, but i'm curious if i can scrap spare parts from it instead (especially sensors). I've looked online, but haven't found any evidence of any DIY instructions on how to do this.  I suspect that doing this is extremely difficult, if possible/worth it at all.

How difficult would it be to extract components from an iphone?  What equipment would i need to do this?  Weighing in the cost-benefit of scraping components, is it worth it?


texts: Im currently a year 1 electrical engineering student. May I ask, for a diode-connected PMOS (gate connected to drain), why is |Vsd| = |Vgd| ?


texts: How do I determine the maximum current for charging a li-ion battery?

texts: I have a cell phone that has a 1500 mAh 3.7 V battery.  It comes with a 700 mA charger but I've sucessfully used a 1 A charger with no problems.  I'm now trying to make my own multi-device charging station and my first problem if figuring out the maximum amount of current I can use at 5V?


texts: Confusion with the nameplate of an induction motor

texts:
Regarding the below nameplate of an induction motor:

What is meant by?:

  Δ/Y
  220/380

Does that mean if delta connected the line to line voltage must be 220V? Im confused also because isnt 220 phase voltage and 380 lne voltage? Could you explain this question  with diagram?


texts:
I was wondering if I can "upgrade" a DC biased tape recorder to AC bias with a simple circuit.

I found some schematics for AC bias circuits, but they were all very different, and I'm not sure which one is suitable for tape recorders. I was thinking maybe there's an IC for that available, but again, I'm not sure on that one.

I'd like the most simple solution, which could be easily put on a daughter board and hidden in the tape recorder. I was thinking using a 70kHz oscillator, and adding it to the signal somehow (before the DC bias, as in, removing the DC bias parts).

This is just a little project to play around, nothing serious. I'm not planning to make "professional" recordings on the tape recorder that will emerge at the end of the project. I just want a proof of concept type of thing.

OK, this is how far I've got:

Consider this circuit of the LA4160:

This is a screenshot of the datasheet, page 4.

Now as you can see in the lower left corner, there is a device "Bias OSC". Given the rest of the Datasheet, I might be able to locate the point where this oscillator has to go.

But how exactly do I build this thing? Or is it an IC that eludes me?

Would be nice if someone could take a look at the datasheet I've linked, and maybe point out a thing or two, if I missed something.

Now, the oscillator needs to be a sine wave, but that's pretty much all I know. I don't know which peak-to-peak level, and I'm not entirely sure what frequency. I think somewhere around 100kHz makes the most sense.


texts: What could be the reason these wires need to be connected outside of the sensor?

texts:
Below diagram shows the inner system of a wind-meter and four output wires to power it and collect the 4-20mA output signal as current or voltage by using a resistor.

I verified with a voltmeter's continuity test that the wire gn and bn in the diagram are connected to together innerly as expected from the diagram.

But I don't understand why they need to be shorted at outside of the device as well. I put a yellow question mark indicating the location. What could b e the reason bn and gn are connected at outside since they are already connected inside??


texts: PCB isolation strength VS pad-to-pad distance

texts:
Is there any estimation regarding the relation between PCB pad to pad distance and isolation strength?

If the board is covered with the mask and the minimum distance is 2,9 mm which isolation voltage I can expect?

The red region is the isolated nets.

The age effects (like surface dust) can be skipped in my case as the device will be packed and protected from such particles penetrations.

EDIT:

Actually I need 2 kV isolation. But I'd be much more happy to know the science behind the subject - not only estimation that my design will or will not keep this voltage. This is why I skipped to specify my actual requirements initially.

EDIT 2

After I read the links I've been provided by you I could put the idea in the following form: as I need to withstand 2 kV test (as per my initial requirements) I will redesign the board (if necessary) and then after assembled put it to the test of 2 kV AC voltage applied and than test the insulation resistance which is should be more than 2MOhms @ 500VDC.

So the questions now are:

Is the stated above correct? Is this any proper approach?
How likely that this PCB as it designed right now on a picture above will pass the test (U2 optocoupler is rated to 3,75 kV RMS). As I stated earlier the minimum distance is 2,9 mm from primary to secondary.


texts: How many stages of transistor amplifiers should be used in order to produce an audible output

texts:
I have constructed this amplifier as shown in the circuit diagram:

simulate this circuit – Schematic created using CircuitLab

I have made a few inferences:

Reducing the value of emitter bypass capacitor reduces distortion but also reduces the gain. How do I find the correct value for getting good performance at audio frequencies?
Using this single stage I am able to get very less audio output. Its almost inaudible. If I use a second stage, I get highly distorted output. However it is audible to certain extent. What should I do to reduce the distortion without affecting the gain?
Can you please provide the design steps involved in choosing the capacitor values?


texts: Design a combination circuit which can detect prime numbers from 0 to 15?

texts:
No idea how to attack this question, full question being:

  "Design a combination circuit which can detect prime numbers from 0 to 15.  There should be a single output line, which would be 1 if the input is a prime number, otherwise the output line would be 0"

How would I go about completing this question? It looks fairly involved.


texts:
I'm looking into designing a power supply for an RPi that can take both USB and battery at the same time, but only pull power from one of the sources. I'm not quite sure how to go about it, I was thinking of using some mosfet switching circuitry but when simulating I was getting some pretty large voltage drops across the Fet temrinals.

My other solution was just having both input power supplies go through a diode and into a buck/boost converter that outputs 5v. I'd really like to keep it as efficient as possible, and couldn't find much online regarding multiple power input switching, so any help or pointing in the right direction would be great. I'd also like to avoid having the battery draining when it's connected to power, so would rather a switching circuit that turned off the other power supply.


texts: How to prevent voltage regulator board heating up and how thick traces should be?

texts:
Im designing a DC-DC voltage step down regulator based off of a switching regulator IC from texas instruments. I have designed the schematic and board accordingly and it should be able to supply 5A at 5v (According to the IC)

Above is the board ive designed on EAGLE. I'm very new to PCB design and my worry is the board may heat up. The IC says it can handle 5A but it is so small as well as each trace being thin. I know there are trace width calculators but I dont know what 'Input Thickness' is. Can someone explain how I would find out how each thick each trace that will be delivering high current should be and also if the IC will heat up and what I could implement to prevent that?
Thanks.


texts:
I'm Computer Science student and I'm having a hard time understanding this task:

Answer is:

Va for DC = 0V, Va for AC = -1 - 3j

Vb for DC = 4.8V, Vb for AC = 1 - 1j

I have a couple of questions considering this circuit:

What does "voltage at a point" mean. I'm used to calculating node-voltage, voltage over capacitor/resistor etc. but how to find voltage at a point? Should I choose a reference node and calculate node voltage in some way or is it some difference of voltage between a resistor and capacitor?
Is there a difference in calculations between regular DC voltage source and Vcc source?
I planned to use superposition to find required voltages. Is there a possibility of simplifying this circuit before superposition? Is it the best method?

It would be great if someone showed me how to solve it step by step.

Edit: Thank you a lot, now this task seems much clearer. However I'm still having some problems with calculating voltage over A and B for AC.

My solutions for DC matched with answers above, but I don't know if my calculations for AC are wrong or answers are false.

Calculations:

Total impedance: Ztot = R1||R2 + 1/jwC + Rg =>

(24k * 12k)/(24k + 12k) + 1/(j * 100 * 10^-7 * 6.28) + 8k = 16k - j16k[Ohm]

Voltage at B = voltage divider over R1||R2: VB = (R1||R2)/Ztot * Eg =>

8k/(16k - j16k) * 4 = 1 + j [V]

Voltage at A = voltage at B + voltage divider over capacitor: VA =VB + (1/jwC)/Ztot * Eg =>

(1 + j) + (-j16k)/(16k - j16k) * 4 = (1 + j) + (2 - j2) = 3 - j [V]


texts: A subsystem with randomised outputs (no microcontrollers)

texts:
I'm trying to make a subsystem that has several outputs. By default, all outputs are 0. When turned on, I want it to randomly set one output to 1, and make it stay at 1 until reset (the reset procedure can be anything, but is preferably a pulse). I'm a bit of a newbie at electronics, but I know all of the basics. Apart from the basic components, I have access to 555s and most of the 4000 series.

Preferably, I would like to avoid the use of a microcontroller.


texts:
I'm using 2 ultrasonic sensors to reverse the direction of a ram using a couple of relays to reverse the polarity.

Basically when the head of the ram comes within range of one sensor it switches the polarity and should travel back until it's within range of the second sensor.

However as far as I can see, as soon as the ram moves outside the range of the first sensor its distance resets and the ram then moves back and forth to just inside and outside the range of the sensor.

Is there a way to program the first output to latch and reset when the second sensor is triggered? Or would I have to build an external latching circuit to achieve this?


texts: Low voltage / high current rectifier using MOSFET

texts:
I was wondering if the following approach to make a very low voltage / high current rectifier (~0.1 V, 1 kA DC) from 230 V AC has any sense or not. Aiming at simplicity rather than effectiveness, I sketched the following diagram:

Here you can see transformer with 230 V AC input (shown at the top) and two secondary outputs (shown at the bottom), say of 18 V AC. Naively, I was thinking to add another single-turn secondary with MOSFETs that can simply be controlled by voltage from Zener diodes. So, would anyone comment if actual rectification on the A-B output can be produced in such circuit?


texts: Multisim Transient time point did not converge (peak detector circuit)

texts:
I'm building a peak detector circuit with mcp6002 op amp. The signal is 8k Hz 20%dc square wave filtered through a low pass filter whose capacitor varies between about 10pf to 1000pf. The schematic is as follows.

Multisim simulation reports this error.

Any idea on how to fix the circuit or fix the software would be really appreciated. Also I was initially using lm358p instead of mcp6002 but found that the output swing doesn't cover the full range of the signal (could reach 4.5V). Is there a more suitable choice (cost is another major issue) in this case?
Thanks!

EDIT1:

I replace the 555 with an ideal signal source. The simulation could run a little while longer before it shuts with the same error again.


texts: using avr atmega32 as web server using ENC28J60 chip

texts:
looking for help on making a website on ATMega32 using the ENC28J60 chip
iam searching for more than a week .. i found many already-made projects on this, but nothing worked with me .. iam very confused through various projects where everyone is using a different method.
also the mikroc example for this ethernet module (after configuring it a little in the HTML code) didn't work with me ..

first, i want to know how to simulate the ethernet module RJ45 on Proteus, so that i can try the code on simulation before the real-time.
if anyone is familiar with this avr-ethernet based website i'd appreciate his help.
i think my problem is in the code (firmware), as i bought an ENC28J60 board where i just connect the SPI pins directly to my MCU and it's VCC & GND.


texts: What capacitors do I use for an 8 MHz crystal?

texts:
I am having a crystal issue with my microcontroller which is an ATmega32U4. Also if you are wondering why I don't just use the internal oscillator, it is because I need to track times with this PCB as I am trying to make a watch for running.
Either way, I am using an 8 MHz crystal for my PCB, but I believe the crystal isn't working because it wouldn't progress any cycles until I messed with the crystal pins with a multimeter. I believe it has something to do with the capacitors I have hooked up to it and I want to confirm it.
I was using 22pF capacitors on my previous versions, but after looking into more math I believe that 43pF capacitors would be a better choice. Here is the crystal I am using (datasheet).
On a previous PCB I was using a 16MHZ capacitor(link) with a 9pF load capacitance with 22pF capacitors and it ran fine. The current PCB has a 8MHZ capacitor with a 20pF load capacitance and 22pF capacitors as well, but it doesn't run. Another difference was the fact that I was using a SMD crystal instead of a through hole, but I wanted to solder the crystal in so I swapped to a through hole design. The PCB I am working on right now is also a really dense compared to my previous project which had plenty of space to spare.
Here is also a basic picture of the PCB layout:


texts: Is there a magnetic field between capacitor plates while the capacitor is charging?

texts:
I've just began studying Maxwell's equations today and what really had my attention is Ampere's law, the second term in particular.
$$\int\vec B \cdot d\vec l=μ_0I_{encl}+μ_0ε_0\frac{dΦ_E}{dt}$$

Does this mean that a changing electric field can cause a magnetic field? For example, during the charging of a capacitor, between the plates where the electric field is changing.

I saw an exercise example where we changed the voltage across a capacitor and thus created a magnetic field between them.But some websites state that as long as there is no current - charge movement at the place of interest, there is no magnetic field being created. I read the same about the capacitor in particular. Could the example be wrong or is there a difference ?


texts: Why MOSFET transistor doesen't do the switching?

texts:
I'm using MOSFET transistor IRFP260N for switching on and off 12V light bulb. The light bulb is between + of 12V battery and drain of a MOSFET, and a source is on the minus pole of the battery. A voltage between gate and source is pulsating around once a second and I can measure about 5,5V there.

When I'm using 12V 6W bulb circuit works fine - a light bulb is switching on and off, but when I changed the bulb with 12V 21W the bulb doesn't come on (filament gets red just slightly and doesn't switch on completely. Also, MOSFET starts heating up a lot and that was not the case with 6W bulb. Can somebody help me to understand why I can not use MOSFET to control switching of 12V 21W light bulb?


texts: Drop test with load cell: longer impulse on load cell than optically

texts:
I have been performing a simple drop test on a load cell using a golf ball, recording the impact using a Phantom camera as well as collecting the data from the load cell.

The problem arises when you compare the 2 time measurements for the impact of the golf ball on the load cell plate. The phantom camera gives an impact time  of approximately 0.65ms whereas the load cell reading from start to end gives a much greater reading (approximately 0.85ms) as seen in the picture - also the 2 gradients from start to peak and from peak to end differ significantly, which we know is not true during a golf ball impact.

How do you explain the time readings being different?
How I could go about getting a more accurate value from the load cell
that matches the phantom camera?

I have also been calculating the impulse of the impact and comparing it to the area under the graph on the load cell readings to check that the force readings are correct, however I cannot determine if they are right - most likely due to the time reading being wrong.


texts:
A professor is writing the general form of a Transfer Function as:

$$H(s)=k\cdot s^{l}\cdot \frac{\prod\limits_{i=1}^{m}\left(1+\frac{s}{z_{i}}\right)}{\prod\limits_{i=1}^{n}\left(1+\frac{s}{p_{i}}\right)}$$

but in every book and in every source that I have found is never mentioned that way. The poles and zeros are never in fractions in the numerator and denominator. Am I missing something? Has anyone any source to explain the logic behind this specific form of Transfer Function?


texts: What would be the waveform of output of this circuit?

texts:
I want to know what would be the waveform of Voutput of the schematic below

simulate this circuit – Schematic created using CircuitLab

The Falstad Simulation

I tried to solve it using circuit simulation.
So I guess the peak voltage at output should be Vi+5V-0.7
but I am really not sure and don't know how to approach to this problem.

So can you please explain me what and how would be the waveform of this circuit ?

Note:Please excuse my poor English.


texts: Is it possible to drive a net from two processes when the assignments are conditionally mutually exclusive?

texts:
In my experience, driving a net from two separate processes (or always blocks) is a bad idea and will result in a multi-driver error in the tools.

However, one of my acquaintances claims that if the signal assignments are contained within if statements that never assert at the same time, it should be possible to drive one signal from two always blocks.

As a test, I did this in Vivado 2014.4. Here is my very trivial test code:

// always block one
always @ (posedge clk) begin
   if (rst) begin
      RegA <= 0;
   end
   else begin
      if (RegA_in_valid_1) begin
         RegA <= RegA_in_1;
      end
   end
end

// Always block two
always @ (posedge clk) begin
   if (rst == 0) begin
      if (!RegA_in_valid_1 && RegA_in_valid_2)
        RegA <= RegA_in_2;
   end
end

As I expected, Vivado does produce errors:

[Synth 8-3352] multi-driven net RegA_out_OBUF[31] with 1st driver pin 'RegA_reg[31]__0/Q'
...

After this test, said acquaintance still claims that this code would synthesize in previous versions of Vivado without errors. This got me thinking - what does the synthesis tool use to determine if a net is multi driven? Does it use the respective sensitivity lists, or is this mechanism feasible (using conditional statements). I see my version of Vivado doesn't work, but what is the consensus in general?


texts: Atmega328P - PU Not Working Properly (Instability, goes to sleep mode after some usage)

texts: I have successfully designed & tested a circuit using arduino uno for controlling a dc motor (MAX 50A,12V,SHORT-DUTY) By using a relay module and current sensor (configuration given in schematic). Then i tried to convert it into a PCB & designed a schematic (given below) & fabricated it, I use the same Micro controller (Atmega328p-pu) which i used in arduino board (program it using arduino uno & put it into PCB). when i tried to run it works for first cycle of my application (when i press switch 1-on & when current reach 5A have to off) but after 1st cycle Atmega328P-PU freezes & it does't get any input from switches (if i use arduino uno instead of Atmega328P-PU means it works well) , i have tried all the possibilities to make it work but failed. Help me!!


texts: Dusk dawn motor driver with polarity reversal

texts:
I'm trying to accomplish this. When a dusk dawn switch is on, drive a small DC motor for a few seconds and then stop.  when the dusk dawn switch is turned back off, then turn a small DC motor THE OPPOSITE WAY for a few seconds and then stop.

Or to say it another way:
Input circuit closed, then close motor circuit for variable time (1-60 secs) with default polarity +-, after variable time expires then open motor circuit.

Input circuit open, then close motor circuit for variable time (1-60 secs) with reversed polarity -+, after variable time expires then open motor circuit.

I can handle the input circuit, but the timer and reversing polarity are stumping me. anticipating DC motor in 12V range <5A


texts: AC current measurement with LT1078 opamp

texts:
First off, please forgive me if this is the worst design ever. I am just learning with experience.

Here is a design for an AC current measurement

simulate this circuit – Schematic created using CircuitLab

I was following the article put forward by LT themselves. On LTSpice i get the same voltage as the input but i wanted a second opinion before i purchase the components. As a beginner to Opamps i can understand the article but not sure if my design is correct.

Thanks in advance.