texts: Need help in biasing TIP31 in common collector mode- edited

texts:
I am using an Arduino Uno board and R-2R DAC to obtain a signal which should vibrate a transducer connected across RL of common collector amplifier using TIP31C.
I need around 300mA of current to vibrate the transducer which is much like speaker (resistance is about 10 ohms).

I have calculated the biasing resistor values, by using the link from guitarscience.net,(sorry forum is not allowing to insert the link) as  R1=39ohm and R2=82ohms with Vcc=5Volts for all the components.
But I dont get the waveform shown in the fig (1) instead output is always HIGH.
I have measured the voltages for the above values using multimeter and they are, VBE = 3.7V, VCE = 1.8V, VRL(voltage across the load) = 3V

Then used the link available from hyperphysics (sorry forum is not allowing to insert the link) and used R1=31 kilo ohms and R2=55 kilo ohms
upon measuring VBE = 0.5V, VCE = 4.8V,  VRL(voltage across the load) = 0.4V and this time output is very much suppresed but has the same shape of the input.

Kindly help me to bias the bjt properly. The images are as below:

[![enter image description here][2]][2]

My first constraint is I have to work with 5 Volts for all the components.So arduino, LM358 and TIP31 are all at 5volts supply.

The previous ckt was incomplete and the complete ckt is as below (Fig 3), here the R1 to R11 = 20K ohms and R12 to R18 are 10K ohms and
R19 is the load (of about 10 ohms). Upon measuring without connecting the transistor, i.e. with only arduino, R2R and LM358, I am getting 2.5 Volts at the point 'A' as well as 'B'.(seems to be working properly).

But when BJT anlong with the load is connected across TIP 31C (removed biasing resistors after the previous reply), the output at 'A' = 2.5Volts and But at 'B'=0.5 volts, VBE=0.5 Volts, VCE=5Volts, VRL=0 Volts.

Kindly tell me the mistake


texts: Through what mechanism does the voltage rise when brushless motor is decelerated

texts: What is the mechanism behind this effect? Why does the voltage rise proportional to rate of deceleration? Can the voltage go beyond Vsupply + back-emf of the motor? What about currents in the motor during this sudden deceleration phase: can they get out of hand? Is it the current or the voltage that tends to destroy components on the control board during such scenario? Even when components are rated for 2x the supply voltage, it still is very easy to burn something when rapidly decelerating the motor electrically.


texts: Using an automotive stereo capacitor for other uses

texts:
I am looking into using a capacitor to buffer voltage drops for a 12V solar power system.  Since it seems I need a pretty big Farad number to give at least half a second of buffer time for my load, I noticed that there are plenty of large capacitors for sale for use in automobile stereos.  It seems like a good way to buy an inexpensive, well-packaged cap.

Example: 1.5 Farad capacitor w 20 Volt Working Voltage/24 Volt Surge

My question is, would using something like this be any different than using a "parts" capacitor from one of the big electronics sites?  Would there be any special considerations or things to look out for? Another possible advantage is that some of the more expensive ones offer things like polarity reversal protection, which would be nice because of the high Farad value.


texts:
I have a PDM-Mems Microphone which provides me with 101010 data, the Microphone has a Clock of 3Mhz. I read the manual about how PDM is generated, but I haven't worked with digital filters yet and in the manual only stands to use a Low-Pass. But I can't find a formula for a digital Low-Pass filter.

My question is how can I perform a digital Low-Pass with the PDM-Output data?

Microphone:
https://learn.adafruit.com/adafruit-pdm-microphone-breakout?view=all


texts:
This is a bit of a general question. I have a project I want to put together similar to the 'sentry gun' projects seen on youtube. I've gathered an SSC-32 servo controller and couple of small servos - i think they're around 76oz-in - and I made a little brace so they are attached at right angles. This basically works as a pan-n-tilt mechanism, and I've plugged the controller board into my serial port, and it all works nicely. The problem is that it's a bit too dainty.

I need way more muscle, and so my question is in several parts.

Where is a good place to get hefty servos for a good price? I need something that can easily swing a 2x4 around (around 2')
Can someone point me at a tutorial for hooking this up? I assume the SSC-32 board and it's 4 AAs won't cut it as I'll need more power for those bigger servos. So How do I control the servos with the board but power them separately?
Would there be an advantage to using stepper motors instead? Like, more torque/$? I've never dealt with steppers, but I heard they were similar.

Thanks for any advice!


texts:
I was looking for a very simple solution to control the speed of a 5V-9V DC brushed motor, while testing with 4 AA 1V batteries, afterwards with a 25c 2 cell 1250mah LiPo.

I have zero background in electricity and such but would like to learn during the process, the first tutorial I found and followed was this.

I have 2 potentiometers: one with 500k rating the other with 50k.
I started tried the link above with the 500k one and it all worked fine on the 4 AAs, but when I switched to the LiPo the potentiometer started smoking and burning up.

So I moved on to a different guide which said all I was missing is a MOSFET.

Following this guide things seemed to work (now with a 50k pot). However I noticed that at max power the motor was getting only 3.65V from the 4 AAs that were producing about 6.12V.

From the little I understood, MOSFETs have very little resistance once you pass the RDS(on). This is the spec of the one I'm using.

My question is: did I simply pick a bad one? Where in the spec sheet can I see how much power is lost even when I pass the gate threshold?

Also, I did find another schematic very similar to the one above that said I should switch the negative to the gate, controlled positive from the pot to the source and then connect the drain to the negative of the motor.

Though this seemed to work there were 2 side effects:

I can barely control the speed of the motor, once it passes the threshold on the pot, there is like a 3% range in motion where it goes from no power to full power.
When it's on low power the MOSFET heats up very quickly.

What is the correct way to hook things up? Am I using incorrect ratings?


texts: I want to know if it is possible to debug a powerPc MPC555 microcontroller on the device while its running with the binary not the source code. If it is possible then please tell me how to do it using BDM and what debugger and software should I use Thank you


texts: 1V on ADC pin with DMA continuous requests

texts:
I have a STM32G071 Nucleo Board and also the IC itself.

In CubeIDE, I set a pin as ADC and activate DMA and enable the DMA continuous request in the ADC settings.
After executing the code and starting ADC, there is always 1 V on this pin no matter if the pin is connected to the plant (circuit) or the ADC pin is open.
Why there is 1V on this pin when the DMA continuous request is enabled?

I could not find any information on the datasheet as well. Below is the schematic of the Nucleo Board.

https://www.st.com/content/ccc/resource/technical/layouts_and_diagrams/schematic_pack/group0/89/90/f2/80/b8/a8/49/6d/MB1360-G071RB-C01_Schematic/files/MB1360-G071RB-C01_Schematic.pdf/jcr:content/translations/en.MB1360-G071RB-C01_Schematic.pdf


texts:
I was wondering, can I connect the CAN H and CAN L terminals of a MCP2551 or SN65HVD230 transceiver to the 12V and GND to send signals to other devices that are connected the same way?

I always thought CAN was meant to be used over the DC wiring (I think it works like that in cars...?) but I have looked through the datasheets and cannot any reference to it...

Anybody have any experience/insights in this?

Thx,
Jeroen

PS and suppose it can be used over 12V lines what to do with the terminator resistors (120 ohms), this would cause a continues power drain of ~100 mA at both terminated sides...


texts: Testing an inductors self reasonant frequency

texts:
Yesterday I was building an LCR meter which wasn't functioning correctly. After some researh online I found that the self reasonant frequency of inductor has a part to play as well. If I understood the video correctly, the self reasonant frequency is basically the frequency where the inductor stops functioning without being connected to any other components. According to the specs from Farnell, my inductor only has a reasonant frequency of 1K. oops

The problem is I built lady ada's minty boost phone charger with an inductor I don't have the spec for. How do I know the self resonant frequency is correct? I have had stability issues with the circuit before. I suspect the inductor is pants.


texts: Selection of current limiting resistors to limit the current of ESD UART / I2C buses

texts:
Since the connection to the I2C and UART buses goes through connectors, where there is a possibility of ESD formation, I would like to limit their current. As the protected device there will be a microcontroller (Atmega328P).

For these purposes, I want to use resistors. There is not much space for TVS diodes.

Options:

I2C bus speed - 100 kHz
The speed of the UART bus is 115200 baud.

Tell me, what values of resistors should be used for these purposes? In order not to harm the signal.

I had a choice between 100 Оhms and 1 kОhms. Maybe you should choose a different resistance.

Thank you!


texts: Leaving extra coils on a transformer unconnected

texts:
I have been looking for a center tap transformer for use in a dual +/-15 volt supply using 7815 and 7915 linear voltage regulators. I have obtained a transformer from an old stereo amplifier, which has a 52 volt coil with center tap, which will give me a nice solid 26 volts which I can rectify and feed my voltage regulators.
However, there is an additional coil on the transformer as seen in the diagram below from the service schematic of the amplifier. I measure about 50 volts across the orange and blue transformer output. I don't need the output from this second coil.
So the question is, what are the consequences of leaving this coil unconnected? Would this have any impact on power supply noise in my circuit?


texts:
I'm very interested in replicating a design published by NASA here : https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670027843.pdf

Specifically the arrangement on Page 11. I have a similar design using a hybrid coupler, and this is very nearly what I want to build in terms of antenna system, but I don't understand how the coax is attached to the antenna elements as shown in this diagram.

I already got an answer to this exact question on ham.SE:

  It doesn't make much sense to me either, or rather, the details are
  not specified adequately. What is specified in the document you
  linked is:

    The near quarterwave monopole, fed as one half of an opposed pair of antennas has an input impedance of the order of \$80 \pm45^{\circ}\$. It
    is therefore possible to match the impedance to either 50 or 100 ohms
    depending on system requirements. Usually a plot of impedance vs
    length of the antennas in the proper structure is made and a
    convenient value of length selected to facilitate matching. The
    matching components (all reactive) are installed in a small chamber in
    the base of each antenna. This permits the rest of the feed system to
    operate in a low loss balanced condition.

  (I assume that \$80 \pm45^{\circ}\$ is a typographic error and \$80 \pm45
> \Omega\$ was meant.)

  The only “opposed pairs” in this system are the pairs of antennas 180°
  out of phase, such as the pair of #1 and #3.

  Since #3 is (called) a monopole, at the end of a 50 Ω feed line, it
  must be fed in the manner of a ground-plane antenna, with the spacecraft's outer shell connected as the ground plane.

  Then since there is a 50 Ω line to the left and a 50 Ω line to the
  right of #1, we must conclude that the thing called a matching network
  in fact incorporates a power divider to split (or combine) the
  signal between #1 and the line to #3.

  I don't find this very plausible, but it's the best interpretation I
  find so far of what's written there.

I would assume that it would simply be the center of the coax, but this doesn't really make sense with the way I understand connecting coax to an element.
If someone could explain the connection to the antenna that would be appreciated.


texts: Is it ok when components touch each other (with body, not leads) after assembly? I know that resistors should be ok, but how about capacitors? Is it ok when I assemble them densely? Will there be any magnetic or electric interference (inductance?) if they are too close? How about other components?


texts: How much battery power for LED and how to make it flicker

texts:
I am trying to figure out what configuration of battery(ies) I need to power this LED. I am only using one (specifically the warm white 1-up).

I am also looking to make it flicker like a candle with the smallest item possible that will NOT reset every time it is turned on/off. I need to to always turn on and flicker correctly. EDIT/ADD: Is there a resister I can include in a simple circuit with a battery pack to make it flicker? It seems like thats what a lot of the cheap tea lights use.

For context I am trying to make super bright LED candles. So everything I use needs to be able to fit into a smallish pillar candle (~1.5-2.5" diameter x min 6" height). And I am on a pretty tight budget, so please let me know what are the cheapest options.

Thanks!


texts: how to determine the resonance frequency of a split ring resonator?

texts: how to determine the resonance frequency of this Split Ring Resonator ?


texts: Calculating resistance for zener diodes?

texts:
I am an electronics student, and I was set some homework online. I am not having trouble with the question itself but the theory. It says that the current through the resistor is the same as the maximun current that the diodes can safely handle, but as you can see, there are (\$V_{out}\$) volts being dissipating to the right, and a minimum required current going through the diode to maintain consistent voltage.

The thing is, how could the current through the resistor be the same as the current through the diode, as \$Voltage=J/C\$, or, joules per coulomb, so that means there must be some energy carried by the coulombs, and ultimately, some electrons. But then this is contradictory, wouldn't the current going through the resistor be the total current, the current dissipated to the right and current through the zenor? Or... is it that there isn't, then, any current passing at \$V_{out}\$? and it doesn't represent voltage being dissipated? I cant wrap my ahead around it...


texts: Wide input voltage range buck converter/circuit to 3.3V 150mA

texts:
I am building an appliance that should work in very wide range input voltage:
In some scenarios input is 5VAC, in other scenarios it can be 250VAC.

It's not a problem to convert AC to DC, then convert it using converters to required 3.3V for the appliance. The appliance consumes current from 10mA to 150mA on 3.3V.

Requirements:

Wide input voltages range.
Small size as possible.
Less components as possible (footprint, size, price).
Less heat dissipation (efficiency in other words).
Low current, very low voltage, low output power.

Till now I used 2 separated power supplies for low-voltage and high-voltage scenarios (switching between them mechanically):

simulate this circuit – Schematic created using CircuitLab

There is not a risk of HV input on LV circuit: the input controlled by dual way relay.
This approach has following disadvantages (for my point of view):

Mechanical switching is not so nice.
Waste of space in tiny appliance.
Maintaining BOM with similar by function parts.

I looked for an alternative solution to merge 2 PSUs in one. Ready PSUs are huge in size: more than inch (25mm) in one of dimensions.

In this thread it was suggested so far "the best" solution based on wide range regulator LR8. Minimal input of 13.2V is not a problem, I can ignore lower input voltages...

Disadvantages for this approach are:

No replacement parts for LR8 in case of short stock.
Supply of 1 regulator is not enough. Connecting LDOs in parallel is tricky and not trivial for me. The avoiding overload one of them and lazy load on other is a big deal.

In this thread the idea of LED driver was suggested.
In common, this is good idea except following:

The most of LED drivers are working in range 80V and up. (At least, I didn't find lower input voltage LED driver).
LED driver is build to maintain constant (limited) current. In my appliance, when current not required (10mA consumption) the driver will raise the voltage to reach the preset current. This will burn the appliance itself.

Additional idea to get wide input voltage PSU can be implemented (in science fiction :) by connecting sequentially 2 regulators LTC3639 of Linear. Each regulator can deal with 5-150V range. So 2 in a sequence can deal 10-300V which maybe enough. But I have no clue how to connect them... I think this is not possible. True?

So, I ran out of ideas to solve the problem of single wide input voltage range buck converter/circuit to get 3.3V output at 10-150mA.
Please, help.

What can be better: develop new research direction or improve LR8 LDO regulator in parallel?


texts: Want Square Waves based on Injection Timing of 4-Stroke Engine

texts:
Recently, I am working on ECU of CNG Auto Rickshaw having 4 Stroke Engine.

Here, Image shows the Engine of Auto Rickshaw.

I have already taken reading of MAP, TPS and RPM. And now I am working on Injection Timing.
For that, I am taking signals from RPM socket(As I don't know which sensor it is).

Here, In Image there is RPM Socket from which I am taking Signals by connecting probe of Oscilloscope to Yellow Wire.

And I am getting Signal like given in this Image,

Now, I want signals as showed in below Image,

I have tried getting this signal using LOW PASS FILTER followed by SCHMITT TRIGGER and getting this kind of result,

So, I need help in getting proper square wave signal.....

Circuit that I have implemented....

1) Schmitt Trigger

2)Low Pass Filter


texts: Repairing old computer, randomly reboots due to something is wrong with "reset" circuitry

texts:
I'm working on a TRS-80 Model 100.

Not long ago, I have done some capacitor repairs after experiencing random reboots. I've skimmed through some online manuals, and it seems that somewhere in the circuitry around the on/off switch is somehow correlated with the reset button. I replaced all the bad capacitors in this section of the motherboard in this picture I found online.

I replaced P with an electrolytic cap. 0.47μF, 50V.
I replaced O with an electrolytic cap. 1μF, 50V.
I replaced J with an electrolytic cap. 4.7μF, 50V although the original is a 25V.
I replaced M with  cap. 33μF, 16V although the original was a 10V.

  I've replaced all 10uF 16v capacitors that are used for the display.
  Recently, I had to replace B and D as it was a bad solder.

  I've damaged the trace near b and d but was working just fine and it
  hasn't severed the trace completely.

I checked the other in the circled that wasn't mentioned above and they did not leak. Although I had to desolder them and put them back again. I made sure that working old capacitors were properly seated and connected through the solder.  I even checked the non-polarized C, and it was not leaking so I had to re-solder it carefully.

I'm confused right now as what to do. All bad capacitors have been replaced.... I'm not sure why its doing this....

Works for a while then randomly reboots after entering the telecom. So which is why I checked the C capacitor (has to do with the modem?)

Somewhere in the service manual, it talks about a battery voltage detector. I suspect that since the capacitors in the circled area have gone bad is the culprit of the "reset." But I was mistaken. After replacing the bad capacitors I still was experiencing reset. So I decided I must have done an improper solder. I made certain that the solder sunk into the holes where the capacitors are supposed to be at and nothing but a black screen of death. I'm scratching my head right now. Did I short something by mistake?

Here is the service manual, look for page 50

Here is the capacitor list and map.


texts:
I'm working on building a silicon free computer and I need a way to store information after power off. Right now, solid core memory seems like the best option. However, the sense line of solid core memory produces a very small pulse of electricity when activated, and I need a way to boost that current enough to flip a relay (~3v,.7A).
TLDR; how can I boost a very small amount of voltage without using an IC or transistor?


texts: Low amps high volts vs high amps low volts?

texts:
What is the difference between the two?
Why would you use say, 5 volts and 2 amps, over higher voltage and lower amps?


texts: I have a Bluetooth receiver and was wondering if there was a way to have it turn on when power is plugged in without having to press the on switch? the middle button is the on/off switch.


texts: potential difference between emitter-base and collector base constant, i.e 0.6 or 1.2v approx?

texts: i was solving questions on bjt, and i came across a question where i had to find voltage across emitter and collector and the answer was 2V, but i have read it's approx. 0.6v across both emitter base and collector base, then how does it amounts to 2v ?


texts:
I have an 8-bit number that the values ranges from 0 to 99.  I need to convert that to a proper 8-bit BCD representation of the number using digital circuits.

In case you need to know, the original value is a temperature value read from a ADC and I need it in BCD to display it in two 7-segment displays. I cannot use a micro-controller.


texts: RPM of two 300rpm motors is not equal, what to do?

texts: I have two 300 RPM motors. But one moves slightly slower. Hence the robot does not move exactly straight. I tested various PWM values and now I am getting very less angle of turn. i there any other way by which the robot would always go straight?


texts: Equivalent resistance problem on cascode mirror circuit

texts:
I'm trying to analyze the cascode mirror, specifically its sensitivity to VCC variations.

Before facing with complicated calculations with the equivalent circuit, the tutorial (I'm following)  advices to find the equivalent of the circuit block on the right of point A, giving only the final result of Req :
$$R_{eq} = \frac{v_{A}}{i_{B}} = \frac{2(1+\beta)}{g_{m}}$$
but without explaining the line of reasoning used to find it, with the only exception to consider equal the transconductances of Q1 and Q3.
By using different approaches, I tried different times to find the same result for the equivalent resistance, but I was not able to find it, and to find an expression for the voltage on point B, too.
At this point, I guess that the circuit block on the right of point A cannot be solved, and that the tutorial is wrong, unless I'm missing something important...
Could some of you help me to find a line of reasoning in order to find the above expression for Req?


texts: what is d-sub connector metal shield made of?

texts:
I want to solder a ground wire to the d-sub connector's metal shield( the bright color metal part of the connector), using tin-lead solder 60-40. I just wonder what kind of metal it is. I searched the web and couldn't find the answer.

This kind of connectors


texts:
Below is the circuit I used to implement an active load which use an op-amp to adjust the mosfets' resistance based on DAC voltage at the op-amp input.

VIN_NANO is about 10VDC.

Mosfet is IXYS IXFH28N60P3, Vds: 600V, On-resistance: 260mOhm @ 14A,10V Vgs, power dissipation: 695 Watt.

The scheme works well with Battery String voltage of 12VDC. When I increase it to 125 VDC, the mosfets die almost instantaneously. What would be the reason behind this?

Test load current looks like this:


texts: Where can I find a datasheet/info of/on this "music speakers" 35 segment LED display with 7 legs?

texts:
Bought some "music speaker" thingies, some with bluetooth and some without. They are cheap, for sure, about 3 or 4 euro's. With some capacitor tweaks, they seem to be very plausibel to use (why is the output on these cheap things always tiny and limited?).

On these devices they use a very tiny, nice and bright display, with 7 legs, charlieplexed I suppose (wiggle it to see any screen update), 35 segments. Cannot read the number on the used chip (it's from JL), very hard to recognize (even when using a microscope) and the display doesn't have any partnumber on it either, however, these seem to be identical except the face plate on these components.

The displays are very interesting, just 7 pins to do the display job, in just one package. I want to buy these things (cannot find it, doesn't know the name and cannot find a datasheet either).

Next thing I want to do is to interface with these devices by reading the display (with a MCU for example) so I am able to read the state of the device and what it is doing. This is a difficult task without any datasheet.

Does somebody know the name of this component, is there a datasheet available somewhere?

Photo gallery of the display:

Product picture:


texts: LTspice simulation doesn't agree with predicted transfer function

texts:
I am trying to create an integrator in LTspice that I will use as a subcircuit in a signal chain later, but can't get the simulation results to agree with my theoretical calculations. I derived the following transfer function:
$$
H(s)=\frac{R_2}{R_{1}R_{2}Cs+R_{1}}
$$
When I used MATLAB linear simulator to test the response of this transfer function to a 5 Hz square wave, I got the expected result: a triangle wave at steady state. However, LTspice would not cooperate.

This looks almost like a differentiator. I double and triple checked to make sure I had the transfer function right. I also built the physical circuit, and measured a triangle wave output at steady state. Can someone help me make my LTspice simulation produce the desired results?
I'm somewhat of a noob with LTspice so I apologize if I left out any important information needed to diagnose the problem.


texts:
I am curious to find out the functionality and working of below circuit.

￼


texts:
I'm currently trying to get a 200kΩ resistance from scrapped materials or new ones but there's a limited range. (There isn't a good supply of components in my city and we can't spare too much time at the moment)

Is there any inverse formula to get the combinations of resistors where their final resistance value is N ?

We don't want a lot of resistors in series but if we lack a solution we will go after that.


texts: Best way to provide clock signals for a low input voltage charge pump

texts:
I would like to use a charge pump to step up a 1.5V AAA battery to >7V. The charge pump itself is already constructed and works fine when I test it with a 5V input. At this point I'm providing the clock signals using a microcontroller. However, the microcontroller can't operate at 1.5V, and eventually I'd like to power the microcontroller from the output of the pump. I am not sure what would be the best way to provide the two out of phase clock signals that the pump requires. I've had some success constructing a multivibrator using capacitors, resistors and MOSFETs, as shown on p. 16, Fig 1-26 here:

http://books.google.ca/books?id=-sE7JVywygQC&pg=PA15&dq=multivibrator+mosfet&hl=en&sa=X&ei=AXR_U_PnDs3foASw1YG4Dg&redir_esc=y#v=onepage&q=multivibrator%20mosfet&f=false

This works fine from a 5V source, but getting it to run successfully from a battery is proving more difficult. I can see that there are various low-voltage multivibrator ICs available, but these are pretty big and seem like overkill for such a simple application.

So, how would one usually go about providing the clock signals for a low input voltage charge pump?


texts: Anything wrong with connecting L298Ns in parallel?

texts: Although L298Ns are very inefficient, they're very cheap. I have two motors that require 4A+ current at load combined. Can I connect multiple L298Ns in parallel in this way to increase the overall current output? Am I going to run into any problems?


texts: Calculate work done to remove a electron at the above position from nucleus to infinity

texts:
i'm doing this question and I'm at the last part now. The first question wanted me to find out the electric field strength (r= 3.0x10^-10m, q= 9.6x10^-19C) and i used coulombs law and i managed to get the answer = [9.6x10^10Vm^-1]. Now the question is asking me to calculate work done to remove a electron at the above position from nucleus to infinity but I'm unsure about how to find this. I understand that Work = QV but the book is giving me a different answer and I'm not sure about what I'm doing incorrectly.

Thanks,
Neamus.


texts: Based on what should i choose an amplifier to implement a Howland current pump with?

texts: I selected some amplifiers based on their input and output voltage since the howlands Gain is Vin/R also on how much current the amplifier can supply. i selected ones that are 100mA and up, what other considerations should i keep in mind ?? also if you have a recommendation that would be great.


texts:
The following images show NMOS amplifiers circuits with feedback:

a)Transconductance (tension source, current output (RL)) -> current sampling, tension mixing

b)Transresistance (current source, tension output) -> tension sampling, current mixing

c)Current (current source, current output (RL)) -> current sampling, current mixing

.

However, I am not understanding the feedback networks, underlined in a different blue.

a) how is the current sampled?

b) how is the current mixed?

c) how is the current sampled and mixed?

.

I am following 'Microelectronic Circuits' by Sedra Smith, but i am still not understanding


texts: Why do I get a "[Synth 8-5413] Mix of synchronous and asynchronous control for register" warning in Vivado?

texts:
The code bellow is to take the reciprocal of a fixed point number using Newton's method.  When start is asserted the state machine enters the estimate state. To get a starting point, I start at 1/2^N where N is the index of the most significant bit. It seems to work fine in simulation but when I synthesize it I get the following warning:

  [Synth 8-5413] Mix of synchronous and asynchronous control for register abs_n_reg in module qinv. ["/home/chase/vivado-workspace/FixedMath/FixedMath.srcs/sources_1/new/qinv.v":45]

I'm not really sure why I'm getting this or how to fix it. abs_n_reg is the absolute value of n. I'm only setting its value from one of my always blocks.

  module qinv(output reg signed [63:0] inv,
                output reg ready = 1'b1,
                input signed [63:0] n,
                input start,
                input clk);

        reg sign;
        reg [63:0] abs_n;

        reg [63:0] cur_inv;
        reg [63:0] next_inv;

        localparam READY = 2'b00,
                   COMPUTE = 2'b01,
                   ESTIMATE = 2'b10;

        reg [1:0] state = READY;
        reg [1:0] next_state = READY;

        wire [5:0] mb;
        msb m(abs_n, mb);

        always @(posedge clk or posedge start) begin
            if(start && state == READY) begin

                if(n[63] == 1'b1) begin
                    abs_n <= -n;
                    sign <= 1'b1;
                end else begin
                    abs_n <= n;
                    sign <= 1'b0;
                end

                ready <= 1'b0;
                cur_inv <= 64'b0;
                state <= ESTIMATE;

            end else begin
                state <= next_state;
                cur_inv <= next_inv;

                if(state == COMPUTE && next_state == READY) begin
                    ready <= 1'b1;
                    if(sign) inv <= -next_inv;
                    else inv <= next_inv;
                end
            end
        end

        wire [63:0] p1, p2;
        qmul m1(p1, abs_n, cur_inv);

        reg [63:0] diff;
        qmul m2(p2, diff, cur_inv);

        always @* begin
            next_inv = 0;
            next_state = READY;
            diff = 0;

            if(state == ESTIMATE) begin
                next_inv = {1'b1, 63'b0} >> mb;
                next_state = COMPUTE;
            end else if(state == COMPUTE) begin
                diff = {30'b0, 2'b10, 32'b0} - p1;
                next_inv = p2;
                if(next_inv[63:1] == cur_inv[63:1])
                    next_state = READY;
                else
                    next_state = COMPUTE;
            end
        end

    endmodule

    module msb(input [63:0] n, output reg [5:0] m);
        integer i;
        always @* begin
            m = 0;
            for(i = 0; i <= 63; i = i + 1)
                if(n[i] == 1'b1) m = i;
        end

    endmodule

    module div_test();

        reg clk = 0;
        always #5 clk = ~clk;

        wire ready;
        wire [63:0] out;
        reg start = 0;
        reg [63:0] in = {8'd207, 24'b0};
        qinv d(out, ready, in, start, clk);

        initial begin
            #5 start = 1;
            #10 start = 0;
            #1000 $finish;
        end
    endmodule


texts: Switching setpoints of a low voltage monitor

texts:
I'd like to build a low-voltage monitor that is adjustable by flipping a switch to one of two setpoints. There are plenty of sample circuits, below is  one adapted from here

I'd adjust the R2 and R3 to the setpoints I'm interested in, and then use SW1 to choose which one to use.

My question is, since SW1 will be located off board, plugged into a socket, and possibly a meter or two away from the circuit, will this cause inaccuracy in the circuit setpoints (i.e from varying resistance of the switch contacts, noise in the wires, resistance in the socket the cable plugs into, etc)?

Would I be better off using 2 comparators, each connected directly to its own potentiometer and using the switch to chose between the outputs of the two?

I'm not necessarily set on using this circuit, if there's a more appropriate monitoring IC or other circuit that would work better, I'm open to options.

simulate this circuit – Schematic created using CircuitLab


texts: Scenarios where Inductor back EMF would result in damage of circuit or component

texts:
Let's say that there is a simple circuit with the following components (ignore values):

LEFT: a simple power supply (assume DC)
TOP: load (resistor) and inductor
RIGHT: switch
BOTTOM: load (resistor)

simulate this circuit – Schematic created using CircuitLab

I have come across numerous sources that indicate that if the SWITCH suddenly moves from a CLOSED position to an OPEN position, the circuit and its components can potentially be compromised if unprotected:

When the switch opens, the current across the entire circuit will drop to zero really quickly (assume instantaneously), resulting in a back EMF
The resulting back EMF voltage according to the inductance formula will be very high as the change in time will be very small
The high voltage produced by this back EMF has the potential to damage the circuit and its components

Below are some assumptions that I hold, please advise if any of them are incorrect or incomplete:

When the switch is closed and has reached steady state, a current will be passing through the circuit in accordance with Ohm's law (V = IR) or somewhere near there.
When the switch is closed and has reached steady state, the current passing through every wire on the main circuit is uniform (i.e. the wire before and after the power supply has the same current passing through it).
Current is the main factor that controls whether the wire in the circuit is damaged or not.
When the switch is opened, the resistance across the open circuit remains the same as it was when the switch was closed, therefore the current generated by the back EMF through the circuit inversely proportional to the voltage generated by the back EMF (Ohm's Law).
Since the current passing through the open circuit is equal to or lower than the current passing through the closed circuit (inductance over short period of time), the wires and its components should be able to withstand the back EMF without any damage (exception are voltage sensitive components such as transistors, diodes, etc).

What scenarios would result in the back EMF potentially damaging the circuit and/or its components and what solutions could be taken to mitigate the problem?


texts: How likely is it that this chip was damaged?

texts:
I am trying to use a dataflash memory that requires a voltage of 2.7 to 3.6. Before I was supplying it with too little voltage. Then I supplied it with 5V. Could either of these cause damage to the chip?

The part number is W25P80 and the datasheet is here.


texts:
Hey, yesterday I saw a demo (which was actually meant for my seniors) of a PSoC 5 board by cypress at my college. They demonstrated how to use the capsense built into the board and one of the PSoC chips to turn an LED on and off. This is basic Hello World stuff.

Although I thought it was cool and all, I really couldn't figure out in what way could I use those boards. Yes they eliminate all the need for making my own hardware, but how would I use this capability?


texts: What will be the reading of AC voltmeter if it is connected to a DC supply of 120V?

texts: What will AC voltmeter show when connected to a DC source of 120V


texts:
I'm coding on PIC24F and I'm still fighting with oscillator configuration. Between configuration bits and SFRs such as CLKDIV and OSCCON I am a 'bit' lost... I've been making things work by trial and error but haven't yet understood exactly what I am doing :/ (like when you finally understand pointers and have the "ohh" moment).

I think the parts that I am missing are:

are configuration bits shortcuts for SFRs? do they overlap?
what are the default/start values and which ones should I touch?
how can I verify that the clock is running at the correct speed?

If more specific this needs to be, I'm trying to setup a PIC24FJ with an external 12Mhz crystal.

Edit:

// CONFIG2
#pragma config POSCMOD = HS             // Primary Oscillator Select (HS Oscillator mode selected)
#pragma config I2C1SEL = PRI            // I2C1 Pin Location Select (Use default SCL1/SDA1 pins)
#pragma config IOL1WAY = OFF            // IOLOCK Protection (IOLOCK may be changed via unlocking seq)
#pragma config OSCIOFNC = OFF           // Primary Oscillator Output Function (OSC2/CLKO/RC15 functions as CLKO (FOSC/2))
#pragma config FCKSM = CSDCMD           // Clock Switching and Monitor (Clock switching and Fail-Safe Clock Monitor are disabled)
#pragma config FNOSC = PRI              // Oscillator Select (Primary Oscillator (XT, HS, EC))
#pragma config SOSCSEL = SOSC           // Sec Oscillator Select (Default Secondary Oscillator (SOSC))
#pragma config WUTSEL = LEG             // Wake-up timer Select (Legacy Wake-up Timer)
#pragma config IESO = ON                // Internal External Switch Over Mode (IESO mode (Two-Speed Start-up) enabled)

// CONFIG1
#pragma config WDTPS = PS32768          // Watchdog Timer Postscaler (1:32,768)
#pragma config FWPSA = PR128            // WDT Prescaler (Prescaler ratio of 1:128)
#pragma config WINDIS = OFF             // Watchdog Timer Window (Windowed Watchdog Timer enabled; FWDTEN must be 1)
#pragma config FWDTEN = OFF             // Watchdog Timer Enable (Watchdog Timer is disabled)
#pragma config ICS = PGx1               // Comm Channel Select (Emulator EMUC1/EMUD1 pins are shared with PGC1/PGD1)
#pragma config GWRP = OFF               // General Code Segment Write Protect (Writes to program memory are allowed)
#pragma config GCP = OFF                // General Code Segment Code Protect (Code protection is disabled)
#pragma config JTAGEN = ON              // JTAG Port Enable (JTAG port is enabled)

Then in my main's init():

OSCCONbits.COSC = 0b010;
CLKDIVbits.DOZE = 0b000;

Am I right to assume the following:?

#define FOSC    12000000UL
#define FCY     FOSC/2


texts:
I'm trying to get a connector that will connect another product as a sort of 'daughter board'.  This thing has the old USB B connector on it and what I'd like to do is back it up to this connector and (since it's male) use it as a point of mechanical contact too.

I'd like something like in the attached picture, but PCB solder mounted.....I've looked for about an hour and a half and can't find anything.

Has anyone ever seen such a creature?


texts: How can I get rid of noise from leds on an audio line

texts:
I am working on a project which involves 8 sets of LEDs being controlled by a micro-controller. The micro-controller is also communicating with an IC which is sampling an audio signal. The audio signal comes from either a 3.5mm jack or an onboard bluetooth audio board. In my first version all the components were connected to the same ground seeing as the micro-controller doesn't have an AGND for me to use. Here is a basic schematic of it:

This caused two problems:

The Bluetooth audio board caused a ton of awful noise on the audio signal when a speaker was plugged in to the project. I learned this was caused by the bluetooth sharing a ground with the audio so I planned to use a B0505S DC-DC isolator to fix this. However, this didn't solve the second problem.

Even when the Bluetooth audio wasn't installed i heard noise on the audio line which corresponded to what the LEDs were doing. I was thinking of using an DC-DC isolator again for the Micro-controller and audio IC, but then I realized that if the Micro-controller was isolated from the ground of the buffer and the LED's i don't think the Micro-controller would still be able to control the LEDs.

My question is how can I isolate the audio from the rest of the circuit while still letting the Micro-controller sample the music and also control the LEDs? Would the DC-DC converter still let the micro-controller communicate with the LEDs even though they are on different GND networks? IS there an LC circuit I should use instead to stop any noise on the audio line?


texts: ESD protection for power input with several fused branches

texts:
I'm designing an industrial board that will be powered with a +24V DC. On the PCB there are several fuses to protect each branch against over-current/short-circuit. Example:

simulate this circuit – Schematic created using CircuitLab
Of course the resistors simulates the actual loads: MCU, relays, LEDs, ...
The 24V is applied through screw terminals.
I need to protect the circuits ("loads" in this examples) from ESD.
As far as I know the ESD protection should be placed very close to the input connector.
So the obviously solution is to add an unidirectional TVS at the input:

simulate this circuit
Usually I put a fuse before the TVS so it can also be effective on persistent over-voltages or inversion of polarity. But here I don't think it's worth to add another fuse!
Is a single TVS enough for ESD protection? Is there a better (= safer, more reliable) circuit to use in this scenario?
By the way, I don't have a real "ground", so I need to close the discharge to the common voltage (0V).


texts: Charge controller for Li-ion or Li-Polymer battery

texts:
I am trying to work out the good charger for Mobile phones, which can serve as good performer for various smart phones out there in market these days & mostly using Li-ion battery. Charging has 4 stages -- "the initial trickle-charging, then constant current charging, then constant voltage charging & finaly Top-up charge" -- all this is controlled & monitored by a control circuit/IC of charger. So, my concern is if such circuit/module/IC is already there in Mobile phones & taking care of all protections to battery/phone including overheating during charge OR The charger designer have to incorporate these circuits in Charger itself? If former case, that means we just need to make a charging source giving ample current & 4.75V-5.25V voltage, like a high-powered USB output port would gives.
My feeling is such stages-wise charging & control/monitor circuitry is already within the phone set, i just want to reconfirm.


texts: How are individual mutual capacitance signal read out from a touch screen?

texts: If I understand this correctly, on a touch screen, you have a a grid based system where the rows and columns are either driving or receiving. When you touch the screen a mutual capacitance arises between the driving and receiving node. How exactly does that capacitance get read out into an (x,y) coordinate on the screen? To be more specific, once the mutual capacitance is induced, how is the signal read out, what does it go through to translate into an x,y position?


texts: STM32F103 simple countdown timer (with no interrupts)

texts:
I'm trying to create a simple countdown timer (without using interrupts) - to use to check for timeout while waiting for an external event to occur.

Ideally, I'd like to preload a timer counter with a specific value and have it count down and stop once it gets to zero - so that I can poll for a zero counter value in my while loop.

I'm struggling to get the timer to run, and none of the examples I can see in the reference manual is this simple.

Can anyone point me towards a simple example of a one shot countdown timer implementation?


texts: I'm looking at a system using a gray code on 16-QAM. When a symbol changes, you move from one of the 16 symbols in the constellation to any of the 16 symbols. I'm wondering if there is in fact an advantage to using a Gray coding? It seems to me to just be arbitrarily renumbering the constellation and won't actually change the performance.


texts:
I'm planning to build a power monitor using an ESP32. The main function would be to control 8 outlets through 8 relays and to monitor the AC power consumed by every outlet with ZMCT103C current transformers and a MCP3208 ADC. As I'm planning to create a PCB, I was wondering how close the current transformers can be placed to each other on the PCB without interfering with each other?
Regards


texts:
I have no experience with electronics but I have a question.
Actually I'm using a circuit for a project that is able to measure RF power at its input in dBm; the circuit provides the integration of a specific component, which is the IC LT5534.
I'm interested in the measurement of the signal strength in Volt/meter, since the law specifies legal limits in units of Volts/meter. I have found (navigating on the web) that in order to convert dBm to Volt/meter, I need to know other parameters ( http://www.qsl.net/pa2ohh/jsvpm.htm ) .
I have also found an RF detector that is able to display in Volt/meter: https://www.amazon.com/Cornet-ED78S-Meter-ElectroMagnetic-Detector/dp/B00P67QLA0/ref=sr_1_3?ie=UTF8&qid=1481739673&sr=8-3&keywords=electrosmog .

How does it work? Is it really possible to convert voltage output (in dBm) to Volt/meter? If the answer is yes, what's the formula?


texts: How does Altium Designer's "impedance constraint" feature work?

texts:
Altium has a design rules option for setting a track width constraint according to line's impedance (e.g.; 50\$\Omega\$). How do I use it? Please give me instructions or a link to an online tutorial. Will this feature affect the default Interactive Routing track width setting when enabled?

Does Altium check line impedance in PCB editor, or should I use Signal Integrity utility for it?

(Note: My application is "GSM module with external antenna".)


texts:
I'm trying to figure out what this diode is.

The marking indicates "A7" and also has "t36" stamped on it suggesting maybe a 1N4007 rectifier diode.

However, when I test it with my multimeter I get a forward voltage of 0.05v and reverse voltage of 1.7 V. Forward resistance of 107 Ω and reverse resistance of OL. Nothing out there seems to match these low values. I was thinking that it's a Schottky diode, but I'm at a loss. The circuit is for a small low power radio transmitter. Below is the schematic and a picture of the diode itself.


texts: Two opposing voltage source, of different current capacities?

texts:
If two voltage source of the same value(20V) are wired in series and they both have different current capacities, could there be any current flow assuming the resistance(internal & circuit) are equal? I assume the voltages being the same and in series to oppose one another they would cancel out regardless of their current capacities?

simulate this circuit – Schematic created using CircuitLab


texts: Driving RGB LED with Constant Current Driver - Only Blue Working

texts:
I am driving a common anode RGB LED using a 15mA constant current LED driver. What really confuses me, is that only the blue light works when plugged in. The red and green ones seem to be dead. Whenever the lead for Red or Green is plugged in, the voltage across either would drop from ~5V to ~0V. I haven't written any code yet, and need help in debugging the LED behavior.
Any input would be appreciated!
The red and green lights are still functional, as I can light them up by tuning a dc power supply. However, they wouldn't light up when connected to the constant current driver.


texts:
I want to design  drone landing pad that will automatically begin charging my drone as soon as it lands, I'm planning on having the drone legs have some pogo pins that will touch the pad it lands on which will have power through it. The issue I'm contemplating is that if the landing pad has a voltage from a cccv, I'm worried it will cause a large inrush current the second it lands on the pad. I wanted to attempt a soft start circuit, I have done some research and lots of typologies use quite a bit of components, I want to make it as simple as possible. Will a simple capacitor in parallel like this work? maybe even adding a Inrush current Limiter like an NTC Thermistor in series for current? Or am I thinking of this way incorrectly?

Also, for reference, the drone battery will need about ~16 V at 23 amps, I placed an 18 V source in LTspice for some voltage drops that will be in the system like a full wave rectifier for reverse polarity  protection etc.. Last thing, I want the ramp up to be about 10 seconds till steady state


texts: Measure frequency of a square wave using capture module

texts:
I wrote the following code to measure the frequency of a square wave using the capture module of the PIC16f1788. I wrote the code by following step by step what is required in the datasheet of this PIC. I would like to know if I have missed any important step in doing so and If my code makes sense. This is the first time that I use the capture module so any suggestions are welcome. Thanks

    #include <xc.h>
    // Config word
    #define frequ  2
    #define _XTAL_FREQ   32000000

    // CONFIG1
    #pragma config FOSC = INTOSC    // Oscillator Selection (INTOSC oscillator:  I/O function on CLKIN pin)
    #pragma config WDTE = ON        // Watchdog Timer Enable (WDT enabled)
    #pragma config PWRTE = OFF      // Power-up Timer Enable (PWRT disabled)
    #pragma config MCLRE = ON       // MCLR Pin Function Select (MCLR/VPP pin function is MCLR)
    #pragma config CP = OFF         // Flash Program Memory Code Protection (Program memory code protection is disabled)
    #pragma config CPD = OFF        // Data Memory Code Protection (Data memory code protection is disabled)
    #pragma config BOREN = ON       // Brown-out Reset Enable (Brown-out Reset enabled)
    #pragma config CLKOUTEN = OFF   // Clock Out Enable (CLKOUT function is disabled. I/O or oscillator function on the CLKOUT pin)
    #pragma config IESO = ON        // Internal/External Switchover (Internal/External Switchover mode is enabled)
    #pragma config FCMEN = ON       // Fail-Safe Clock Monitor Enable (Fail-Safe Clock Monitor is enabled)

    // CONFIG2
    #pragma config WRT = OFF        // Flash Memory Self-Write Protection (Write protection off)
    #pragma config VCAPEN = OFF     // Voltage Regulator Capacitor Enable bit (Vcap functionality is disabled on RA6.)
    #pragma config PLLEN = ON       // PLL Enable (4x PLL enabled)
    #pragma config STVREN = ON      // Stack Overflow/Underflow Reset Enable (Stack Overflow or Underflow will cause a Reset)
    #pragma config BORV = LO        // Brown-out Reset Voltage Selection (Brown-out Reset Voltage (Vbor), low trip point selected.)
    #pragma config LPBOR = OFF      // Low Power Brown-Out Reset Enable Bit (Low power brown-out is disabled)
    #pragma config LVP = ON         // Low-Voltage Programming Enable (Low-voltage programming enabled)

     void main(void)

     {

     int count=0;
     float rise1=0,rise2=0,frequency,period;

     OSCCON = 0b11111010;

     // clear the interrupts at beginning that way we are sure that our calculations will be exact no previous interrupt present
     PIR1.CCP1IF=0;
     PIE1.CCP1IE=0;

    // output
    TRISBbits.TRISB0 = 1; // set it to input
    APFCON1bits.CCP1SEL=1;// toggle the CCP port output to RB0 from RC2

    // configure CCP1
    CCP1CONbits.CCP1M = 0x05;   // set it to Capture mode; on every rising edge

    While (count=! 2){

    count +=1; // increment the value of count

    // configure Timer 1
    T1CONbits.TMR1CS = 0; //set the  timer 1 clock to instruction clock Fosc/4 as mentioned in page300
    T1CONbits.TMR1ON = 1;       //  set Timer 1 on
    delay_us(10); //aquisition time
    T1GCON.T1GO/nDONE=1; // aquisition is ready wait for a rising edge
    while (T1GCON.T1GO/nDONE=1); //wait untill the aquisition is complete

     if (count==1) {

     rise1=CCPR1; }  //capture the first rising edge and store that value in rise1

     if count ==2) {

     rise2=CCPR1; } // capture the second rising edge and store the value in rise2

    }

    period = rise2-rise1;  // subtracte both values to get the period of the signal

    frequency=1/period;

     // clear any interrupts that are set
     PIR1.CCP1IF=0;
     PIE1.CCP1IE=0;

}


texts: How to connect Spartan-6 with ISE 14.2 on Ubuntu

texts: I bought my first FPGA and I'm trying to implement a simple VHDL program on it, but I don't know how to connect it's Atlys board to ISE 14.2. I'm using Ubuntu 64-bit.


texts: Do Xbox 360 Slim power supplies output 5V until connected to Xbox?

texts:
My Xbox 360 won't power on. I cracked open the case (beyond warranty) and started testing voltage points with a multimeter. No point was registering anything. So I tested the power supply, and it only registered 5V, but it should be 12V.

To narrow down the problem, and be sure, would the power supply start supplying the full 12V only when plugged into a working Xbox (like a failsafe)?


texts: Single issue and Dual issue architecture

texts:
I am studying the PowerPC architecture on the MPC5644B. The documents from Freescale mention it to be a single Issue architecture.

The data sheet states the following,

• e200z0h single issue, 32-bit core Power
Architecture compliant CPU
— Up to 80 MHz
— Variable length encoding (VLE)
— Supports Nexus3+

I did some Google search and read forums, this seems to be some kind of Mixed Harvard architecture, but i am not sure exactly what it is.
If anyone could help , it would be highly apprecieated.


texts: Why can't I get correct reactive and real power in what seems to be easy task

texts:
As the title says Why can't I get correct real and reactive power

The task says:

  Source with voltage  \$U = 100\angle{30} \$ is plugged on to impedance \$ Z = 3 + 4j \$. Determine real, reactive and apparent power.

what I did was:

I find apparent power: \$ \frac{U^2}{Z} = 2000\angle{6.87 }   W  \$

And to find real power i tried to multiply cos(6.87) with 2000 and I get \$ 1985.65 \$ but the answer supposed to be \$ 1200 \$. What have I did wrong isn't the real power equals cosφ * apparent power?


texts:
I did a logic network  with only NAND gates to function below:

and my logic newtork

Is it correct?


texts: What would happen if you walked between a lifesize parallel capacitor with an air gap?

texts:
Lets say the capacitor is two 7 foot x 4 foot metal pates distance between is 3 feet and the plates are hooked up to voltage.
At what voltage would it become dangerous to walk through, if any? Assuming weren't wearing anything conductive. If it's never dangerous is that because the capacitance is so low?
Is there a difference in the electric field between the plates if the voltage is dc or ac?


texts: I don't understand why \$ v_i = v_{in} - v_1 \$. Is \$v_{i}\$ supposed to be the inverting input or the noninverting input voltage?


texts: Any downside to feeding a buck regulator into a linear one?

texts:
I need to convert 12 V down to 5 V and 3.3 V.

I am using linear regulators right now but they get pretty warm and eventually I would like to supply more current for it (around 500-700 mA).

If I used a buck converter to get the voltage down to 5 V, then also feed the 5 V into the 3.3 V linear regulator is that acceptable? Assuming the buck converter can handle the current of the 5 V components and the 3.3 V ones? Also, this would cut down on heat from the linear regulator, correct?


texts: Wave from the piezoelectric material is not what I expected. Did I miss a step?

texts:
The wave from the piezoelectric material may be

sine wave (classmate told me )
AC wave (but not sine, I suppose it from the paper)
DC wave (from the oscilloscope it seems like a DC wave, not AC wave)

Steps:

Red oscilloscope line connects to the red line. Black oscilloscope line connects to the black line. No load (resistor or capacitor), as in the picture shown below

Here are the wave situations, shown in the oscilloscope

no press: a horizontal wave which has noise
at the time I press: the horizontal wave goes down
at the time i release: the horizontal wave goes up

After that, the horizontal wave returns back to the original, and this is the reason: I think the wave produced from the piezoelectric material is a DC wave, because there is no AC wave, only DC. However, I read some papers and articles from the internet, and they all said that the wave from the piezoelectric material is definitely not a DC wave. So, did I miss any steps before I tested the wave with the oscilloscope1?

I saw a waveform from this pdf ( Chinese version), and in Fig 14 & 15 there is a voltage waveform, as shown below.

1I’m using a WaveRunner-8000 oscilloscope.


texts:
If a label says 100-240V AC @ 1A do we assume that the 1A is for 100v or 240v ?

Assuming it's 1A at 100v is equivalent to around 0.41A at 240V.


texts: Passing and overwriting parameters to Verilog modules

texts:
I'm studying the way of passing parameters from one module to another and I have one question.

I have this instance in the top level module.

parameter a= 100;
parameter b = 200 ;

test#(b/(a*2)) test(
    .clk(clk),
    .reset(reset),
    .out(out)
    );

In test module, I have this header:

module test#(parameter max = 33 )(
  input clk,
  input reset,
  output out
);

So, my question is:

Which value will the module take as input parameter? 33 or 1 ?
I mean, Is max=33 overwritten by the one I'm passing from the top level module?


texts: Can you explain how the 2-phase dual rail channel works?

texts:
I am doing research in asynchronous circuits. I got to this section of "Asynchronous Circuit Design A Tutorial" by Jens Sparso which explains handshaking protocols.

There are four protocols discussed:

4-phase bundled-data (single-rail)
2-phase bundled-data (single-rail)
4-phase dual-rail
2-phase dual-rail

I understand all the first three protocols fully. I only struggle to  understand the "2-phase dual-rail" protocol.

In the textbook there is a figure which explain how this "2-phase dual-rail" work for two bits data pack (each bit is represented with two wires):

What I don't understand is how those "00", "01", "00", and "11" are inferred from the signals.

The proper tags are "asynchronous circuits", "handshake protocols". But  I could not find those tags, so I set it  to more general tags, like "circuit-design".


texts: Does a 7400 IC used as AND-gate use any power when output is 0?

texts:
If I have a simple 7400 IC and using it for a single AND operation, would it consume any power when the AND is false and outputting 0V?

If so, to what degree? 20mA or 20uA?


texts: How to store more waveform after trigger and less before?

texts:
I have a Rigol DS1074Z and can't figure out how to lower the time the scope spends pre-sampling to open up more memory for the actual data I want to see.

Here is a nice image that will hopefully explain better:

And here is what it looks like when I am trying to store beginning of USB communication:

Unfortunately almost 50% of the 12 million data points are wasted. I would like to move the TriggerPoint in the first image closer to the beginning. In other words, I really only need to see what happens after the trigger triggers (any maybe a little bit before)

Is there a setting I missed? Can this be achieved?


texts: First PIC microcontroller family to learn? and resources? development board?

texts:
The only experience I have with micro controllers is with the arduino. I felt extremely limited by the arduino especially in the cases of embedded design. I'm interested in completing a number of projects with embedded micro controllers and I don't know where to start. In looking at learning PIC micro controllers, I've found a book called "Learning to fly with the PIC24" and it requires an explorer 16 development board. This book seems to be outdated though? I don't know if this would be the best place to start.

I am interested in learning a long term solution in the proper way so that I can be a proficient PIC hardware design electrical engineer. What recommendations might you have for me? There are so many families of PIC chips, I don't know what I should start on. Should I get a development board? Is there a specific book/resource that you recommend? Should I start 8 bit, 16 bit, or 32 bit?

Thanks for your recommendations! I'm willing to spend a lot of time in the near future learning the PIC and I don't want to be wasting my efforts on something too difficult, not useful, or simply outdated.


texts: Shifting an audio signal from 0 - 4V to -2 - 2V

texts: I'd like to transmit an audio signal over a digital radio and I figured out I'd need an op-amp in an inverting configuration on the transmitting side to turn a -2V to 2V signal into a 0-4V one. That will be fed into an ADC which then supplies the radio with a digital signal. On the receiving side though I'd need to do the reverse in order to hear the audio properly, so that means the 0-4V signal now needs to be the -2V to 2V one again. Could an op-amp also be used for this, and how? Thanks for helping!


texts:
I am trying to do this(http://www.arduino.cc/en/Tutorial/Switch) without using any external parts because I was able to use button example from same site with this code: http://en.textsave.org/VjL) with my msp430g2553 using Energia but its not working, any help?

const int buttonPin = PUSH2;     // the number of the pushbutton pin
const int ledPin =  GREEN_LED;   // the number of the LED pin

int state = HIGH;      // the current state of the output pin
int reading;           // the current reading from the input pin
int previous = LOW;    // the previous reading from the input pin

// the follow variables are long's because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int.
long time = 0;         // the last time the output pin was toggled
long debounce = 200;   // the debounce time, increase if the output flickers

void setup(){
pinMode(buttonPin, INPUT);
pinMode(ledPin, OUTPUT);}

void loop(){
reading = digitalRead(ledPin);

// if the input just went from LOW and HIGH and we've waited long enough
// to ignore any noise on the circuit, toggle the output pin and remember
// the time
if (reading == HIGH && previous == LOW && millis() - time > debounce) {
if (state == HIGH){
  state = LOW;
}
else
  state = HIGH;
  time = millis();    }

digitalWrite(ledPin, state);
previous = reading;}


texts:
O holy simplicity. I've seen lots of solutions for this but none that will fit to my scheme.
First of all, lets add simple code:

void setup() {
  pinMode(0, OUTPUT);
  pinMode(1, INPUT);
}

void loop() {
  int a=digitalRead(1);

  if(a==LOW) {
    delay(1000);
    digitalWrite(0, HIGH);
    delay(1000);
    digitalWrite(0, LOW);
  }
}

What the heck I need to add that the IF command runs only once while button is staying in low state and it will be reset eventually when button is set to high again.
I've read five different solutions here and tried them out and yet not working as I intented. Rest of the solutions that I found in the net were complicated and I needed to add libraries or alter the code wayyyyyy too much. I'm trying to find the most simple solution for this simple code. And as it will be simple, for some reason I'm over thinking it and not finding solution myself.


texts:
I was reading this PDF which tries to explain the concept of poles and zeros of Laplace transform. I started with second paragraph on page #590 and read it up to page #592 before the new section "Analysis of Electric Circuits" begins. Please have a look on FIGURE 32-5 on page #591. The following is an excerpt from the same PDF.

Our goal is to find combinations of σ and ω that exactly cancel the
impulse response being investigated. This cancellation can occur in
two forms: the area under the curve can be either zero, or just barely
infinite. All other results are uninteresting and can be ignored.
Locations in the s-plane that produce a zero cancellation are called
zeros of the system. Likewise, locations that produce the "just barely
infinite" type of cancellation are called poles. Poles and zeros are
analogous to the mountains and valleys in our train story,
representing the terrain "around" the frequency response.

It does make sense but I'm facing a problem to interpret a zero in the context of spring-mass system, as I explain below. My question is not directly related to electrical engineering but I'd say an engineer would be in a better position to answer it.
The following differential equation describes a mass-spring system with input force set to zero.
$$y′′(t)+2y′(t)+10y(t)=0$$
\$y(t)\$ represents displacement from equilibrium position, its first derivative would be velocity function, \$v(t)\$. Two initial conditions are as follows: \$y(0^-)=4\$, \$y'(0^-)=v(0^-)=0\$.
Laplace transform: \$Y(s)= \frac{4s+8}{s^2+2s+10}\$
Impulse response: \$y(t)=4\exp(-t)\cos(3t)+1.333\exp(-t)\sin(3t)\$
There are two poles at \$-1\pm 3i\$, and one zero at \$-2\$.
The zero could be written as \$-2+j(0)\$
It doesn't make sense to multiply the impulse response with \$e^{2t}\$. As you can see that area under the curve cannot be zero as the function is diverging.
$$e^{-\sigma t}(4e^{-t}\cos(3t)+1.333e^{-t}\sin(3t))$$
$$=e^{-(-2)t}(4e^{-t}\cos(3t)+1.333e^{-t}\sin(3t))$$
$$=4e^{t}\cos(3t)+1.333e^{t}\sin(3t)$$
Edit #1:
This edit was made after after the comment of @jDAQ.
I also tried to do the convolution in Matlab.
clear all; close all; clc;

sig=-2;

x=linspace(0,50,5000);

impulse_response=(4.*exp(-x).*cos(3.*x)+1.333.*exp(-x).*sin(3.*x));
input=exp(-(sig).*x);

output=conv(impulse_response, input);

plot(output,'--');

Please see the plot here: https://imagizer.imageshack.com/img923/231/Dr6MR4.jpg
You can see that the output is not zero as expected.
Edit #2:
The picture shows the spring-mass system with a damper: https://imagizer.imageshack.com/img924/8415/gK84LJ.jpg. At the beginning the spring is stretched four units toward the right of screen, and then released. The function y(t) shows the displacement of mass around the equilibrium position.


texts: RS485 IC Termination Resistor Configuration

texts:
I've made a mistake on a design, that went into production...

It was built like the drawing on the left, with R702 to 5V and R703 to GND, it should have been backwards... like the drawing on the right.

The thing is... the board passed all the tests, the RS485 communication works fine.

I wan't to know if this difference could result in errors in communication/damage to the circuit if it is left unchanged, or if it's irrelevant.

This board was designed by several people, the desition to add R702 and R703 wasn't mine, and I don't understand why they are there (datasheet for SN75176B doesn't uses them in any case). So a second, and probably more interesting question, would be: why are those resistors there in the first place? What's their function?


texts: Extended Instruction Set mode for PIC18F with Hi-Tech Compiler

texts:
I'm writing some firmware for a PIC18F6622 microcontroller. I use MPLAB IDE 8.73 + HI-TECH C Compiler for PIC18 MCUs (PRO) 9.66.
When I set the XINST (Extended Instruction Set enable bit), the IDE gives me this warning:

What settings should I do to be able to use the PIC's Extended Instruction Set?

EDIT:
Just found on the net: 'If set (the EXTENDED INSTRUCTION flag), your program (or your compiler) must take it into account to use the correct addressing methods'. But what does that really mean?


texts: Transferring arbitrary data via Bluetooth Smart (BLE) with nRF51

texts:
I was wondering if it was possible to send arbitrary packets of data over a Bluetooth Smart (Low Energy, 4.0) link from a nRF51 (Nordic Semi, BLE compliant SoC) to a phone?

Also if you don't know the specific device, any help is appreciated as all I found about Bluetooth Low Energy are pre-configured profiles.


texts:
I am working with a Fluke 8508A, an 8.5-digit table-top multimeter. To my surprise, one of the menu options is a 4-wire DC voltage measurement.

I know how 4-wire resistance measurements work, but I am at a loss how a 4-wire voltage measurement would be beneficial. Does it give higher precision, and if so, how?


texts:
I am a DIY user trying to understand basic electrical knowledge. I’m not sure if I am in the right place to ask so if not, I’m sorry.
I have an LED display screen (see attached photos)that has 4 power supplies connected together (maybe the term is looped). We are running on 100-120 volts and according to the label each power supply draws 6.8 Amps.
I am assuming (and need clarification) that the total load is 27.2 Amps?
If the above is correct (27.2 Amps), does that mean the supply cable (that is connected to the first power supply - e.g main line input) needs to be something like a 30 Amp 10 gauge wire?
Does the wire gauge between each power supply need to be 30 Amp 10 gauge wire or can it reduce in size towards the end power supply?
Also, the blue plastic (PowerCon type) input connector that receives the main line input is only rated for 20 Amps.
Doesn’t it need to be 30 Amps???
Any assistance would be most appreciated.
Thanks


texts: How to extract the switching noise component for this signal data?

texts:
A servo accelerometer when powered by batteries has a clean output, but when used with this SMPS supply its output seems like have switching artifacts from the power supply(the datasheet says its switching freq is 100kHz). Now since the desired range is very low I can easily filter out such noise at the sensor output.

But having said that, I want to know what we can say about the noise at the accelerometer output. So by using a digital scope(at AC coupling mode) I made two measurements and logged the time series data for the standing accelerometer output. The first one is for longer period, here is the screenshot:

Then I plotted the time series and FFT of this as follows:

Then I did the same thing for a smaller time scale:

So by having all these information what can we say about the frequency of the switching noise? I'm trying to learn in such a situation how to quantify the switching noise. Should we look at the time series data or the spectrum for that? And for this particular case what steps should one follow?

EDIT:

For a much longer acquisition I observe the following:

MEASURED DIRECTLY AT THE POWER SUPPLY OUTPUT:

Closer view:

And spectrum:

Supply Output at 50us scale:

Time series and FFT:

The PSU noise(yellow) directly appears at the sensor output(blue):


texts: why does higher current mean lower discharge capacity

texts: I have some confusion regarding c-rate of batteries and its capacity. For example, a battery of 1Ah is discharging at 1C rate. This means it will discharge 1A in an hour. If the same battery is discharging at 2C, does this mean that it that it will discharge 2A in 30 mins? If thats the case why would the capacity of the battery decrease?


texts:
I wonder if it's possible to use certain screws/spacers in a wave soldering machine, so that it will be possible to screw a screw to the spacer attached to the PCB afterwards?

My intial thought is that maybe a titanium screw/spacer might work due to poor Solder-ability but I have no clue if that works.

To understand the problem; I've a heatsink that has to be screwed to the PCB before soldering the TO-220 packages to the PCB. The reason to this is to minimize stress on the legs due to the stiff fitting till the heatsink (only available solution for my application). So I would like to find a solution where it's not necessary to hand solder this specific part, which is the case right now.

Best regards


texts:
Thanks for your patient help, I am learning a lot. This is my (final, I hope) re-designed layout. What do you think?

10-32V to 5V 1.2A SMPS Buck Regulator Design.
The IC is IFX91041 from infineon.

Here are the schematics and layouts:
http://www.mediafire.com/?69e66eje7vda1

(I was given 45 cm² (~6.98 inch²) area for both 5v 1.2A and 35V 4A.)

I did a "print screen" instead of bitmap output.


texts:
I'm trying to integrate LORA communication in a project that uses a raspberry pi.
I've bought this module to serve as a gateway for testing: https://www.amazon.es/gp/product/B076T28KWG/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
My problem is in finding a low cost solution for the raspberry pi so that it can send messages through LORA. I want to deploy multiple raspberry pi so I want to keep costs low on the lora add-on for the raspberry.
Option1: Are there any ready to use raspberry pi lora hats that cost less than 15 euros in Europe?
Option2: Are there any tutorials for connecting lora chips to the raspberry, that are beginner friendly and that clearly explain what the pinout should be to connect the raspberry pi and lora module and what libraries to then use to send the messages?
Also, should i be careful with compatibility between different boards?
I found this github repository with instructions on how to connect an RFM92/95/96/98/69HCW Module to a raspberry pi. My concerns are that it is 4 years old, so there may be better modules today at a similar price. Also, I'm concerned that the modules may not be compatible with my gateway. Finally, the tutorial may not be simple enough for me to succeed.
Does anyone know of a better or perhaps simpler tutorials/github projects that'll allow me to do this?
For context:
I've got some experience with soldering, but really basic knowledge of electronics theory, so I can't really understand what components in a schematic do.
I have fairly good knowledge on developing software with C/Java/Python/... but I don't usually work with low level code as is the case here.


texts:
We are seeking after a motion sensor, probably PIR , that can be covered with regular plastic or ABS ( that means you will have a regular product enclosure where the sensor is inside it ) .

I could see that most of them have this white dome covers them , and i wonder if there is an option to cover them with any material and still let them work as usual .

After all , they are working with temperature so why cant you cover them ?

Is there other physics that i miss here ?


texts: When designing a second-order RLC band pass filter, how can we choose whether to use the series form or parallel form?

texts:
Second order RLC filter can be realized in series and parallel forms.
Suppose we need a high Q factor, if we choose a series form, we need the inductor to have a larger value than the capacitor and the resistor.
Conversely, if we choose a parallel form, we need the inductor to have a much lower value than the capacitor and resistor.
So in real application, how can we decide which form to use?
Thanks.


texts: Any way to measure distance through water?

texts:
I have a barrel of clear liquid which has sediment build up at the bottom of a barrel. Over time I want to measure the build up of this sediment. Nothing can touch the liquid and I can't place anything in the barrel. The measurement must be taken from the top of the barrel. Also the liquid in the barrel is not still. There are ripples and bubbles within the liquid. The barrel is quite small at around 24-36 inches max.

I have been trying to find a way of measuring distance through water but everything I have found uses infrared to measure distance. Why are they all infrared? Obviously infrared will bound off the top of the liquid. The only thing I can see of getting through is a visible light laser such as 650nm red laser.

Is there anyway of doing this fairly reliably. It doesn't need to be doown to the nearest mm. Nearest cm I think would be enough.


texts: SMD pads come in basically two shapes: rectangular and rounded rectangle. Does either offer advantages? For instance for etching, or HF signal integrity?


texts:
The definitions of electromotive force of a cell that i have studied include:

1.When no current is drawn from a cell,i.e., when the cell is in open circuit, then potential difference between the terminals of the cell is its electromotive force.

2.The electromotive force of a cell is defined as the energy spent or the work done per unit charge in taking a positive charge around the complete circuit of the cell i.e., in the circuit outside the cell as well as in the electrolyte inside the cell.

I do not understand what definition 1 means. I think it is probably refers to the work done in moving the charge inside the cell since in the definition it is said that the circuit is open but then its meaning does not match with definition 2. My question is, what is the actual meaning of definition 1 and how is it even related with definition 2.


texts:
I am a beginner in electronics and I want to ask you a simple question.
Can I power my old SE w200i directly from arduino, using resistive divider like this one: https://en.wikipedia.org/wiki/Voltage_divider

r1=100Ω r2=3*100Ω v2= 3.75V.
Orginal battery from this phone is 3.7V. Is there any possibility that it'll work?

//
also i was thinking about something like this:


texts:
I have 3-4 RFID cards in my wallet, and they all work just fine when I press my wallet against the card readers - despite being 4-5 cards deep in my wallet.

I want the benefit of having these cards in my wallet, but in a smaller form factor.

Does something exist that can make that happen?


texts:
I am using a pic 6f628a and I want to use "on change" interrupt on pins RB4:RB7
I also want to use two different interrupts on pins RB4 & RB5 so when either of the pins have a valid change the flag will be set >>> my problem is how to differentiate between the two interrupts coming from RB4 and RB5. I Want to check the flag of RB4 or RB5 but i don't know how to write this line of the code.


texts: I am a novice in power electronics. I don't know when we can call a circuit an extra-low-voltage circuit. for example a circuit in which there's a power supply that converts 240V AC to 24V DC and other components working with 24V DC, is it  an extra-low-voltage circuit? the input voltage of the power supply is higher than  the extra-low-voltage range but the output of power supply is in the range of extra-low-voltage. Is this circuit considered as an extra-low-voltage one?


texts: Is it possible to have two switches controlling the same motor?

texts: Basically I want one (3 prong)switch to allow the motor to spin in one direction, and the second (3 prong)switch will allow it to spin in the opposite direction. Is there any way to do this?


texts: best way to rectify 30kv flyback output?

texts:
i have made a flyback transformer for some HV experiments and am hoping to get around 35kv from it, which i want to use to charge a capacitor, so i will need to rectify the output... i think perhaps some kind of asimetrical spark gap might be able to do the trick but was hoping and wondering if I would be able to string together a load of diodes in series to do the job?

I have some 1n4007 diodes with a max reverse voltage of 1k...  if I put 40 in series will it work, or will they all just melt?  something I read suggested that I would need resistors somehow involved with the diodes to make it function? how would that work?

if the answer is no, does anyone have any suggestions about ways to do this?


texts: Input/output pin resistance for an AVR microcontroller

texts:
For example, when driving a logic-level MOSFET directly from a microcontroller, what is the smallest gate resistor that can be used?

Specifically for AVR microcontrollers; i.e. this datasheet, the maximum current that can be sourced or sunk from a pin is 40mA, for a logic-level MOSFET where the gate is driven between ground and +5V, this would mean a gate resistor of at least 125 Ohms is necessary.

However, I also see other anecdotal evidence (not in the datasheet) that the pin itself has an internal resistance of 25 Ohms; this would mean that only 100 Ohms is necessary for the gate resistor.

I can't find any references to this internal resistance in the datasheet; but it does seem to have some value. Are there any canonical references?


texts: What is a simple voltage limiting circuit?

texts:
I am searching for a neat solution for an input voltage limiting circuit.

Situation:

I have a circuit with an input voltage range from 6 V to 20 V at 3 A peak (the load), however my source can be anything between 7 V and 27 V.

I am looking for a circuit in between that passes through any input voltage between 7 V and 20 V, and clamps any input voltage between 20 V and 27 V to the 20 V maximum of my load. (dissipating 7V*3A = 21 W)

Desired behavior of the 'questionmark' - circuit:

The solutions that already found:

Using a resistor and 20V Zener diode --> Is not preferred because of the losses in the resistor which I don't want if my input voltage is below 20 V, and the losses in the Zener when my load current is near zero...
Using a 6V LDO --> Does not satisfy the requirements, if I do have a 20V input available, I want to 'use' it.
Using a 20V linear regulator --> Unspecified behavior when the input voltage is below 20V...
Using a Zener with a Mosfet as in https://www.circuitlab.com/circuit/9sj5kb/zener-mosfet-regulator/ --> Simulation reveals that when the input voltage is below the zener voltage, the output is ~half the input voltage, desired behavior would be Vin = Vout.


texts: Substitute for LM2937 (5v to 3.3v) regulator

texts:
I made a fatal mistake of designing a pcb without checking the availability of the component in my locality(lm2937 3.3v)..

Shocked to know that it is not available anywhere in India..

Though I have the pcb ready with me, I am unable to complete my project because of this issue..

So, I am looking for some other 3.3v voltage regulator that has the same pin out(TO-220 Plastic Package)..

I need your help people..

The devices getting powered by this are Pic32, Micro SdCard, Xbee module(if it does matter)..

Thanks in advance..


texts: How do I use the flash memory on the Copperhead WiFi Shield?

texts:
I recently purchased a Copperhead WiFi Shield for Arduino, and I have successfully initiated some basic networking over the wifi.

I've noticed that on my Revision of the board (rev.2) there is also a 16Mbit serial flash, "for storing web pages and other data!" is the way they put it. Does anybody have experiencing using this board? I find the documentation is extremely lacking, and really all they give is a lot of source code with what I find to be poor examples to build on.  Any advice on how I can take advantage of the flash memory would be really appreciated.

In some of the sources they have code similar to the following. Is this essentially writing the data to the flash memory?

const prog_char webpage[] PROGMEM = {"<html>...webpage truncated for brevity...</html>"};


texts:
Reference paper

I need to calculate number of battery cycles. I have all required parameters from formula below, but I am unsure how to do it.

Qnom = the nominal charge capacity of the battery and abs(I) = the absolute value of battery current at a time t. Then the effective number of throughput cycles N in the time interval is given by:

I(t) is current which was measured per second (Iit has a lot of measurement values), and it has a varying value for both charge and discharge.


texts: STM32 USB_CDC Firmware to autodetect by Linux

texts:
We are developing a custom board to control brushless DC motors. The board has STM32F405RGTx. We are now trying to make USB CDC communication work. We generated the code using STM32CubeMX.

Unfortunately, when we plug the board in Linux machine (kernel 4.4.14) USB port it is not detected. However, the kernel gives a message that it detected a new device:

sudo dmesg | tail
[346221.900229] usb 1-1: new full-speed USB device number 75 using xhci_hcd
[346222.259132] usb 1-1: new full-speed USB device number 76 using xhci_hcd
[346227.525263] usb 1-1: new full-speed USB device number 96 using xhci_hcd
[346228.765215] usb 1-1: new full-speed USB device number 100 using xhci_hcd
[346230.015198] usb 1-1: new full-speed USB device number 104 using xhci_hcd
[346236.265479] usb 1-1: new full-speed USB device number 4 using xhci_hcd
[346243.515496] usb 1-1: new full-speed USB device number 32 using xhci_hcd
[346250.766546] usb 1-1: new full-speed USB device number 60 using xhci_hcd
[346252.265563] usb 1-1: new full-speed USB device number 65 using xhci_hcd
[346258.265781] usb 1-1: new full-speed USB device number 89 using xhci_hcd

The above is the output after plugging in and out 3 times. As you can see the device is always given a new number and is not completely recognized. Also the message that a new device is detected appears several times for a single time you plug in.

lsusb also does not list the device. Can you point me to what section of the STM32 firmware I need to change to fix that so that the device gets listed under /dev. You can find the code that I am currently using here: https://github.com/nikonikolov/ODriveFirmware/tree/CDC.


texts: Does ZigBee Smart Energy Profile 2.0 support meter data pushing from meters to a concentrator

texts:
I've had a look around but can't find a clear answer.

Can ZigBee Smart Energy Profile 2.0 devices send unsolicited messages to a data concentrator without a poll from the concentrator? Like measurements or event data?


texts:
I need to confirm / refute my assumption about current in LED strips. I know they are usually wired in paralel blocks of several serial connected diodes. This means that current consumed by the LED strip flows thru the entire strip power wiring, right? So if I connect for example 2 strips in series, I will double the current flowing thru both strips. Is this right?

If it is, how much current can typical LED strip handle? I could not find this information for every single LED strip I tried, I only assume this is given by the width and thickness of the copper wire of the flexible PCB used.


texts: Is it possible to hand solder a component with a peak temp of 250 C?

texts:
I'm trying to mount an RF module that has 33 edge castellation pins.  The data sheet says that the peak temperature is 250°C.  I'm using 60/40 lead solder for a lower melting point but the solder will only melt at 315°C and I suspect that I'm burning the gates on these expensive modules.

Is reflow soldering the only way to mount components like these?


texts: novice user needs assistance for three peltiers being connected to a single power source

texts:
I am a novice user, and I am not very familier with Peltier setups, for my old CCD astonomy camera. The Peltier that was broken in the camera is not supplied by the manufacturer anymore, nor will they renovate such an old camera, so I hope that someone can help me out. I am familier with soldering wires together, and I have now purchased three Peltier units that can fit in the small space where the broken Peltier used to sit.

The Power source that runs this old broken Peltier is a 12 Volt DC, and the amps for this system is 3A.

The Peltiers are not to be connected with each other in a serial connection, but the wires from each Peltier unit is to be connected in a common joint with the wire that comes from the circuit board. Can I connect the three Peltiers, each running on 4 Volt DC and by 1 Amp, and then have them work together like they were one Peltier?

I am unsure what the physics will work like during such a setup, so just wanting to be sure, as not to damage the connection in the circuit board, before trying.


texts: Reporting crashes/resets in Embedded Systems(8 bit)

texts:
I'm using PIC controllers, and I have used watch dog timers to trigger a reset in case of the s/w gets stuck somewhere, and also to support in case of severe hardware crashes.
I think that resetting the CPU is good, but reporting the crash should also be a very good viable option to help debugging. I'm currently searching a method to do so. I have an EEPROM with free space for such purpose.

Is there any standard procedure for reporting crashes?
What parameters shall I monitor / trace in such crash reports?


texts: Solar system design: Inverter keep tripping problem

texts: What is the problem when my 2kW pressure washer can only use for 3 to 5 minutes? The inverter drop to 50v and then tripped. My solar system consist of 48v 200Ah battery bank with 3000w inverter (48v system, peak 6000w) and 4 pv panels (290w 32.6v 8.9A per panel, series-parallel connection) charge by 60A mppt controller.


texts: What is the mathematical formula to calculate the voltage of a (typical) LiPo battery as a function of it's charge, current flowing and external temperature?


texts: Troubleshoot a bipolar amplifier circuit

texts:
I am working on a project in which I am attempting to interface with an ILDA galvanometer from an arduino to move around a projected laser beam.  I am following a guide linked here, particularly step 7 at the introduction of the amplifier circuit.

If I understand the logic correctly, the desired function of this amplifier is to take an input of 0-4V on line 2 (driven by the arduino and a DAC) and output a 5V+- signal on lines 1 and 7, following the following relation:

Input 2 = 0V, Output 1 = -5V, 7 = +5V
Input 2 = 1V, Output 1 = -2.5V, 7 = +2.5V
Input 2 = 2V, Output 1 = 7 = 0V

and so on. This circuit is giving me trouble as I don’t particularly understand why it is designed as such, not having much experience in the realm of EE myself. More so, I have run into problems attempting to build it on a breadboard myself, resulting in the following incorrect outputs on wires 1 and 7.

Input 2 = 0V, Output 1 = 0V, 7 = 0V
Input 2 = 4V, Output 1 = 3.9V, 7 = 3.5V

I am not sure if this is a problem with my implementation of the circuit, or a flaw with the circuits design. Any intuition as to what could be wrong with either one, and how to test and troubleshoot would be much appreciated!


texts:
I want to transmit a 125 kHz signal. The square wave signal is generated by the microcontroller (just transmitting no data and no receiving,) the transmitting and receiving antennas are tuned to 125kHz.
I connected the transmitter antenna as the picture below.
On the receiving antenna the oscilloscope shows clear signal and peak to peak up to 80 volts when both antennas are closest to each others, the signal decreases as the distance between the antennas increase.  At a distance of about 7 cm the the signal completely disappears.
How can I design a 125khz antenna driver? (The desired distance is 2 to 3 meters.)


texts:
When I simulate the circuit below in Pspice, the output info says: model J2n5485 used by Q2N5485 is undefined. But I have defined the model in the code.

I need to use the 2N5485 FET in this circuit in Pspice:

My version: 9.1 student.

My .cir:

oscilador de cristal pierce jfet

Vcc 4 0 5
.lib nom.lib
L1 4 1 3mH
C1 1 2 0.001UF
R1 3 0 10M
*|||CRISTAL|||
Rs 6 3 15
Cs 5 6 25e-005
Cp 2 3 6e-012
LS 2 5 10.132118mH

Q2N5485 1 3 0 J2n5485
.lib eval.lib
.MODEL J2n5485 njf
+VTO=-2.3888 BETA=0.00110073 LAMBDA=0.0108464 RD=3.58556
+RS=3.44889 IS=1.44179E-14 CGS=430.467E-15 CGD=433.667E-15
+PB=1.160107 FC=0.5 KF=8E-18 AF=1
+VTOTC=0.002 XTI=3 BETATCE=-0.5

.AC DEC 10 10 5MEG
.PROBE
.END


texts:
Consider This Circuit:

As you can see we have 3 switches and thus three routes to the output, we can control each switch, but only one switch can be closed at any moment .

We do not have any problem with switching part of the circuit (and in fact we can't simply change it).

Our problem with this circuit, if we close the third switch, current will flow in the circuit like this:

we just don't want the current to flow in the second rout (or R1 - Red route), or if we close the second switch we don't want the current to flow in the third route (Or R3) , I think you've got the whole idea, we want our routs lead the current in just one direction, the most simple solution is using series diode on the routes that can cause a voltage drop and we don't want it .

So what do you suggest? I have to mention that output is going to be connected to ADC input, so we just want to prevent any kind of voltage or current drops as far as possible. And if a drop is inevitable, we want it to be constant or somehow computable, so we can set a bias.


texts: Full bridge rectifier forward voltage definition

texts:
I am looking for an efficient way to rectify a 3–20V AC voltage (at  ≤2A) and am therefore looking at integrated full bridge rectifiers and discrete Schkottky diodes. In a datasheet of a full bridge rectifier an “Instantaneous Forward Voltage” of typically 0.49V is stated. I do not find any information on whether this meant per diode, so will the total voltage drop be double that? If yes, why are integrated full bridges so much worse than discrete Schottky diodes (around 0.3V, e.g. CUHS20S30)?
Are there other methods of rectification I should consider? I found the TIDA-00858 reference layout, but four LM74670s would be by far the most expensive item on the BOM.


texts: Looking for a way to connect Edge card to wire wrap using Eagle

texts:
I am working on a project that requires many discrete transistors.  Suffice it to say, it is for a transistorized 4-bit CPU project.  I came across some oldschool IBM info on Wiki, and would like to do something similar to this:

IBM SMS Cards (scroll through to see application)

I want to follow the traditional approach of having all the logic gates on these cards and have them connect to a wire wrap backplane.  I've had a heck of a time finding not only Eagle libraries that support a card edge connector, but it seems impossible to find the exact connector to go with it.  Even something as mainstream as PCI has a million variations.

The cards themselves will be 3x4" single sided copper boards that I will etch myself.  Ideally, the card edge would connect directly to a DIP wirewrap socket.  I'm really not sure the best way to go about this.  I would like an affordable way to connect these 3x4 cards to wirewrap, and would prefer to be able to make the PCBs for the cards vs. using proto/vero board.

I've thought about using angled pin headers, but the card edge seems cleaner and saves a lot of soldering.

I know wirewrapping is antiquated and I also know that having multiple logic cards is as well.  But, this is a hobby and I would like to use old technology.


texts: Keepout in Solder Mask in Altium 17 for SD Card Connector

texts:
I am creating footprint for Amphenol's SD Card Connector in Altium Designer 17. The datasheet shows Pattern Prohibited Area on Page 2. I am assuming there shouldn't be any trace or unmasked via or trace under that area.

In my design, I need to run few traces covered by solder mask in that area. Also, I might be having some vias in that area. For DRC checking, I want to add keepout area in that pattern prohibited area.

Will keepout in my Top Solder Mask layer prohibit any unmasked via in that region? By this, I should be able to run any trace or via covered by solder mask in that area.

If not, what is the right way to achieve it?

My footprint is over here:


texts: Possible to have too much magnetics in Ethernet

texts:
I have a question regarding magnetics topology on an ethernet 1000base t channel. I'm working on a project where I have a board (board 1) with MAC, PHY, and magnetics.

I have another board that mates to this (board 2) through a board-to-board connector. On "board 2" i'm taking the ethernet channels (4 differential pairs per channel) and routing them to RJ-45's with built-in magnetics. Then from the RJ-45's with built-in magnetics, the ethernet goes through standard cabling to an ethernet port on a PC (with built-in magnetics). So, if we follow the ethernet channel it goes

board 1 -> magnetics -> board 2 -> magnetics -> CABLE -> magnetics -> PC

Will 3 magnetics cause noise/oscillation or disturb ideal impedance matching?

According to
"https://www.we-online.com/web/en/passive_components_custom_magnetics/blog_pbcm/blog_detail_electronics_in_action_85119.php"

A typical LAN has 2 magnetics per ethernet channel. I haven't found any resources on multiple (more than 2) magnetics circuits on a given ethernet channel.