texts:
I'm using a barcode scanner that will dump the coded values over a serial port and need to have power also sent to the barcode scanner over the same cord just like with the cord shown here:

Reference: https://superuser.com/questions/1214742/does-this-rs232-serial-cable-require-an-external-power-supply.

Can anyone explain exactly how the wiring inside of the RS232 connector is wired so that it provides power and data transfer to the RJ45 side?

I will be using a barcode scanner into a microcontroller with bare wires so ill need to know exactly what is happening inside the RS232 connector.

Thanks

edit

It appears that the ground for the signal and the ground for the power is shared in this example.

When i wire this way, im able to get power to the scanner but not able to transmit data over serial.


texts: I2S to SPI or some other normal interface

texts:
I need to get the higest possible precision from an analog to digital convertor (and by high I mean 24bits or more), 10 times per second. To this end I've decided to investigate using an ADC that is designed for audio. Unfortunately, after vast amounts of reading and research the only way that I can interface it with my microcontroller, which I can't connect directly to it because of timing concerns. The only way that I can interface it is with an FPGA, which is alot of work for such a seemly simple task. I refuse to believe that nobody has wanted 24bit ADC precision on a simple non DSP microcontroller such as the Adurino or Fez.

Does anyone know of an IC that can interface the I2S bus to either SPI, I2C, CAN, Serial, etc for the purpose of obtaining the 24bit value of the analog signal. Note: The data is not being using for high speed Digital Signal Processing.


texts:
I'm reading cmos camera specifications. But I can not understand one thing. Is the MIPI means MIPI-CSI 2, or is it a different interface? This is the link of the camera I have been interested in.

http://www.ovt.com/download_document.php?type=sensor&sensorid=173


texts:
I am currently in the fourth year of my bachelor's degree and my knowledge on this is really really really very limited, but i got a simulation circuit of an isolated dc-dc converter from my senior and im supposed to identify the losses of the circuit, mainly at the inverter, the transformer and the output rectifier.

From what i found out, synchronous rectification can reduce the losses at the output but switching the switch on at the same time the current flows through the diode, hence reducing power losses and improving efficiency. Looking at the secondary side of the transformer, so basically the gate and source of the MOSFET is shorted so that only the body diode is used, to replicate a normal output rectifier. I was told that this was done because synchronous rectification will be applied later on in the process(that's why MOSFETs are used instead of diodes), but because the controller for sync rect is not done yet, and this was done to replicate a normal diode output rectifier.

But I heard that doing this is not good, and shouldn't be used in an actual circuit, but what exactly about shorting the gate and source is not good in an NMOS? (As far as i know, the thing that destroys an nmos is only if you short the drain to source. I might be wrong :x)

Also about the recovery time etc. of the body diode being worse than a normal diode and stuff, too many things that im not too sure about.

EDIT: Additional question, one more question is that if you look at the MOSFET on the primary side it has a diode connected parallel to it(i was told that this is the body diode and not an external diode), but on the secondary side the ideal NMOS doesnt have the body diode shown. Why is that?


texts: Adjusting a design already found on here

texts:
I found a design found here How to cut power off when a certain voltage from a sensor is reached?

and the last diagram is EXACTLY as I'd like to build but for 10 times the voltage. Anyone able to advise how to do this for 12V battery so it charges up to 13V max anytime it falls to 10.5 or 11V? What components and calculations would be needed please?

Been out of electronics for many many years but I still easily recognise the circuit diagram above.


texts:
Wondering on how could higher pitches than 23 kHz be measured, I can only find devices measuring to about 21kHz.

Main question is: how could audio frequencies about 26 kHz or 30 kHz be measured, on dBFS and frequency; ones on my smartphones, television and woofer only reach 21 kHz.


texts: What Is the Best Way to Debug an AVR Microcontroller Using the Command Line?

texts:
My AVR programming method is usually as follows:

compile the source code with avr-gcc:

avr-gcc -mmcu=<mirocontroller_id> <source_file>.c -o a.out

Convert the compiled code into hex with objcopy:

objcopy -O ihex a.out a.hex

Write the hex to the flash of the microcontroller with avrdude:

avrdude -c <programmer_id> -p <microcontroller_id> flash:w:a.hex

This works great. Its fast, reliable, and very flexible. Now I want to add onto this toolchain with debugging functionality. I have heard of something called avr-gdb, but I don't know a whole lot about it. Documentation is difficult to find, and there is little information out there on it. I would love to be able to set breakpoints, and read the state of watched variables in the microcontrollers memory, as well as being able to see a hex dump of the memory.


texts: 8086 Memory segment falling on 16-byte boundaries

texts:
I was reading in 8086 datasheet and I found this phrase that I couldn't understand in memory organisation :

  memory is logically divided into code, data, extra data, and stack
  segments of up to 64K bytes each, with each segment falling on
  16-byte boundaries.

I know what segmants mean but what they mean by "... segment falling on 16-byte boundaries...


texts: Is it possible to generate user-defined signal using an android phone?

texts:
Is it possible to generate an electronic wave signal using an android phone? (Theorically)

For example by customizing the firmware can I produce some signals like \$ f(t)=2 \sin 3.2×10^9t+3\cos 5×10^9t \$, where its units are \$W/m^2\$(Watt per metric meters), and \$s\$(seconds)?


texts: Solve a circuit with the nodal analysis (3)

texts:
I have the following circuit, and I have to find Vo:

I solved it in this way:

$$
\\
\begin{cases}
\frac{v_1 - 40}{1} + \frac{v_1 - v_0}{2} + 5 = 0
\\
\frac{v_1 - v_0}{2} + 5 = \frac{v_0 - (-20)}{8}  + \frac{v_0}{4}
\end{cases}
\\
\begin{cases}
2v_1 - 80 + v_1 - v_0 + 10 = 0
\\
4v_1 - 4v_0 + 40 - v_0 -20 - 2v_0 = 0
\end{cases}
\\
\begin{cases}
3v_1 - v_0 = 70
\\
4v_1 - 7v_0 = - 20
\end{cases}
\\
v_0 = 3v_1 - 70
\\
4v_1 - 21v_1 + 490 = -20
\\
17v_1 = 510
\\
v_1 = \frac{510}{17} = 30 V
\\
v_0 = 3v_1 - 70 = 20
\\
\begin{cases}
v_1 = 30 V
\\
v_0 = 20 V
\end{cases}
$$

But the solution is this:

I think that the error is in the solution, because in the first equation there is:

$$
\frac{40 - v_0}{1}
$$

instead of:

$$
\frac{40 - v_1}{1}
$$

but I'm not sure. Is my solution right or wrong?


texts: How to find out the values of a surface capacitor

texts:
Surface resistor has numbers on it to decide whether it's good or bad after measuring it with DMM.

But when I looked at surface capacitors, they don't have numbers or strips to decide their validity and to replace them with new ones with the same values (In case they're bad). So how to find out surface capacitors values (Voltage - Farad)?

Thank you in advance.


texts: Automatic cut mains power on a thunderstorm

texts:
I am a software engineer with only a basic experience with electric/electronic engineering.
I live in a rural area subject to thunderstorms, my house is the end of the line from street poles. It's common to receive lightning strikes by energy line. I have grounding, surge protectors, etc, but somehow sometimes a surge is capable to hit and damage my UPS.

It's a common recommendation to unplug sensible/expensible eletronics on thunderstorms. I am wondering if it's possible to automate this process.

With an Arduino it's not so difficult to make a "lightning detector". This could cut-off mains power from some equipment on a thunderstorm and turn it back on when it stops.

I am not sure circuit breakers, relays or contactors are able to isolate a lightning strike because of the small air gap between contacts when they are off. In other hand, if you consider that a lightning is capable enough to jump from a cloud in sky to the ground, even if you unplug an equipment from the wall, a strike could jump from the wall to the disconnected plug. If you imagine, for a very small probabillty, that NO ONE is safe.

So, I ask, there is some kind of relay appropriate to isolate a lightning strike?


texts: What's the difference between all of these video inputs?

texts:
Over the years and with the large variety of hardware I've dealt with I've used quite a few of different video inputs and outputs. While I usually have no issue just plugging cables into devices, I really started to wonder how video cables differed from each other.

Could anyone specify the difference between s-video, rgb, rca, component, composite, vga, hdmi, displayport, dvi, and any others I'm forgetting? Why do these cables keep evolving; what does an hdmi cable offer that an s-video cable does not, for example? What are the advantages of using one cable/input over another? Refresh rate? Input lag?


texts: Estimating inductance change by eddy currents

texts:
I have a planar coil with inductance L, operating at a given frequency.
Now I want to estimate the eddy currents, which are induced in a piece of metal, which is placed in front of the coil, and the change of inductance caused by this eddy currents.

Which would be the best approach to this, by calculating the field equations, or is there any simpler approximation possible?


texts: Low current, long life batteries with an extended temperature range?

texts:
I'm working on a product with a specified -40 to 85 degC temperature range, and I'd like to have a RTC with a coin cell or similar battery backup.

Beyond that temperature range, damage to the battery is acceptable... as long as it doesn't explode under 125 degC.

I also believe that my initial client's industry has an aversion to the word "lithium", so lithium-anything is potentially problematic.  (Unless I can point to something very authoritative saying it's perfectly safe and that it adds no hassles in shipping requirements)

It doesn't need to be rechargeable, really. It'd be a bonus, but not a requirement.

What reasonably attainable battery fits these criteria?


texts: What is the relationship between DMX and RS485? Are there any breaks in the protocol in relation to one another?

texts: As far as the DMX is RS485 and at what points one moves away from the other? breaking the standard/protocol?


texts:
I thought this would be trivial to source. Looks like the usual molex style connector. But it seems to have a 1.8 mm pitch:

Any ideas what kind of connector this is? I cannot find anything with this pitch. I'd rather not cut the cables for this project.


texts: Why is it that the Δ-Δ transformer needs much higher input power than the Δ-Y transformer?

texts:
I'm in a course where we wired up a single phase transformer as delta/delta and delta/wye and tested the current on the secondary side, Is. I noticed that we needed more than twice as much input power in the delta/delta configuration as we did in the delta/wye configuration to generate the same secondary current.

Delta/delta

Delta/ wye

Does anyone know why this is?

Cheers.


texts:
I am developing for the NodeMCU V0.9 with the NonOS SDK and can't get it to communicate to a DHT22 sensor.

Wiring: 3.3V on NodeMCU -> + on DHT22, Ground to - and pin D1 to signal, there is a 6.8k pull up resistor on the data line.

According to the DHT22 datasheet, the MCU has to start by pulling the data line low for a bit more then 1 ms after having it on high for 1 ms and then hast to listen to what the DHT22 is sending.

My code for doing this is the following:

gpio_output_set(_pinNumber, 0, _pinNumber, 0);
os_delay_us(START_SET_HIGH_TIME_US);
gpio_output_set(0, _pinNumber, _pinNumber, 0);
os_delay_us(START_SET_LOW_TIME_US);
gpio_output_set(0, 0, 0, _pinNumber);

I was able to verify that the NodeMCU behaves as expected by using a logic analyzer (see picture)

I ruled out a defective DHT22 by trying 3 different ones.
The DHT22 doesn't answer with the data as expected.

Has anyone encountered this behavior?


texts: Is a motor-generator set a reasonable way to get the purest waveform electricity?

texts:
It looks like audiophiles go as far as installing separate powerlines to power their high quality audio systems. The motivation is that the amplifier and other hardware would run cleaner when the powersource provides cleaner waveform and with a separate powerline the amplifier will not be affected by various electrical devices run by other households.

Let's not assess whether any audible difference can exist because that's highly subjective. I'm interested in the purest waveform of the powersource part.

That separate powerline

can be hit by lightning
is also parallel to many other wires around it and so can be affected by processes in those wires
is connected to a large grid which has tons of transient processes happening all the times

so it doesn't really sound like a reliable best purest waveform source.

Would a motor-generator set run on the original powerline be better? It looks like it doesn't care much about all those lightnings, parallel wires and the grid.

How good is a motor-generator set for generating the purest waveform electricity?


texts:
I'm trying to put my ZVS buck converter (DCM) in closed loop. I ran some simulations on MATLAB, and figured that just multiplying the transfer function of the open loop buck by 0.5  gives acceptable settling time, phase margin.
Now to implement this in the circuit, I used two inverting amplifiers, -0.5 and -1 (given by U3 and U4). The switching frequency is 300 kHz. So I tried to compare the output of U4 with the sawtooth wave of V4 whose period matches the switching frequency 300 kHz.
But I get a convergence error in Pspice. What am I doing wrong?

EDIT 1:-
So I understood I made a mistake in the isolation of the gate pulse supplies,

This is the erroneous result I am always getting:-

The output should be 200 V. I checked the feedback circuit was working or not by replacing U2 with a diode, and it didn't give me any errors, but I'm not sure this proves that the feedback loop is not the problem.


texts: Developing \$C_{out}\$ spec for DC Bench Power Supply

texts:
I'm designing a DC Bench Power Supply, following the general design procedure described by Christophe Basso in his book Designing Control Loops for Linear and Switching Power Supplies: A Tutorial Guide. Partly it's because I'd like a better bench supply (this will form new "guts" for one of my vintage HP 721A supplies, but mostly because I want to study control loop design.

The general procedure divides the overall converter into the plant (aka. modulator) and a compensator. One determines the transfer characteristic of the plant, then designs the compensator to produce the optimum loop transfer characteristic (bandwidth and stability) when the compensator transfer characteristic is "multiplied" by that of the modulator.

My question is: Is \$C_{out}\$ part of the plant or part of the compensator?

Putting the formal design steps aside, what I need to understand is: When in the design process do I determine the value (including perhaps ESR) of \$C_{out}\$? Can that be determined solely by "pre-compensator" specifications, like perhaps output impedance? Or is it really part of the compensation scheme? Or perhaps it's one of those messy design points that really needs to be considered several times in the process?

I seem to pick up the notion that \$C_{out}\$ is considered part of the plant, but at least in my design, it adds (in conjunction with \$R_{load}\$) a low-frequency pole that is pretty critical in the compensation scheme.

This is my schematic so far, with boxes delineating the modulator/compensator boundaries as best I've been able to determine them:

Right now the loop transfer characteristic has the following poles and zeros:

\$p_1\$ - \$R_{load}C_{out}\$, about 3Hz
\$p_2\$ - low pole of LF411, about 15Hz
\$z_1\$ - \$R_1C_1\$, about 350Hz
\$p_3\$ - \$f_{hfe}\$ of the 2N3055, around 10kHz

It's quite stable on simulation and on the bench, but the bandwidth is pretty low and \$C_{out}\$ seems a bit hefty to me, I just arbitrarily picked that value as a starting point based on what was in my Agilent E3610 (which has 15V/3A capacity vs. 30V/300mA for this one).

Anyway, I'm thinking it's time to get \$C_{out}\$ dialed in and just wanted to know if I'm putting the cart before the horse here.


texts: Getting to know why my meter does what it does: 11 volt LED tester question

texts:
While all your great answers to my previous question are simmering in my brain (I printed out all your answers and placed a copy on my work bench to have another go at it), I have one more:

As I mentioned in a previous post, I have a new model UNI-T UT89XD meter.  A unique feature is that it generates up to over 11 volts in "diode test" setting.  The question I asked an expert was this:

How does the 11 volts of LED testing not burn out a 3 volt LED?

He initially answered: "The output is controlled so it only sends out the required voltage."

And being the curious noob I am, I asked:  "Can you supply a brief, laymans explanation of how it senses voltage capacity of a low voltage LED?"

He responded: "The forward voltage works by trying to force a constant current of (lets say) 1 mA through the device under test (diode). Forcing the current through the DUT will drop voltage (forward voltage for a forward-biased diode). The maximum voltage is then limited to whatever the multimeter can output in diode mode. Rather similar to how resistance is measured, but instead of calculating the resistance from the voltage and the current using Ohms law, it displays the forward voltage directly. So if the 1 mA results in a drop of 0.5 V, the resistance range would display 500 Ohm (0.5 V / 1 mA), while the diode range would display 0.5 V."

Now I suspect his answer makes sense to most of you guys but not so much to me.  But I didn't want to press my luck asking him to clarify that for a noob thinking that he might be thinking his attempt would be something akin to explaining the theory of relativity to a fly.

So, can anyone out there in electronics land give a more "layman" oriented answer to how that meter can deliver up to 11 volts to an LED without blowing out a 3-volt LED?


texts: My inverter produces over 240V AC, will it fry my equipment

texts:
I purchased a couple of batteries and decided to connect an inverter to invert the DC from the battery to AC. But before I connected any equipment I decided to test the voltage from the inverter, it is producing well over 240Volts AC.
Could this fry whatever equipment I connect to it or my equipment can handle the tolerance?Below is a pic of the AC voltage being tested producing 262Volts


texts: Humbucker-style microphone interference cancelling

texts:
For a recent experiment, I decided that it would be a good idea to try to add some electric guitar distortion effects to my otherwise Classical flute playing.
In order to do this, I attached a small electret microphone to my flute, which is powered by a phantom power unit and provides an audio signal to a guitar amplifier. A rough idea of my setup is shown in the following circuit diagram:

simulate this circuit – Schematic created using CircuitLab

(I did not include component values as I don't think they are that important in this problem, but I can add them if required.)

This setup seems to work quite well, I am able to add as much distortion as I want using the amp. However, there seems to be a bit of interference (mains hum, etc.) present, as there probably would be in proper electric guitar setup. My friend, who plays electric guitar, immediately noted that I should try to implement something similar to a Humbucker pickup, which is a type of guitar pickup that cancels out most interference, but with microphones instead of pickups.

My understanding of how a Humbucker pickup works is that instead of having just a single pickup, there are two, wired in series or parallel. The pickups have opposite magnet configurations (ie. one has all magnets with the north poles pointing upwards, and the other has magnets with the south poles pointing upwards) and wire coils wound in opposite directions. Any interference induced in the coils is then cancelled out because the interference from each coil is equal and antiphase in relation to one another. The signal from the guitar string remains unaffected because the although the coils are wound in opposing directions, the magnets are also in opposite polarity.

Based on that understanding, I came to the conclusion that it isn't possible to replicate the Humbucker setup with my microphone, because there is no equivalent to "winding the coils in opposite directions" or "reversing the polarity of the magnets" in an electret microphone. Simply connecting two of my microphones in series or parallel (which I believe is what my friend was thinking) would increase the audio signal but also the amount of interference, due to the microphones (and therefore interference) being in phase with each other.

So my question is, is it possible to replicate the concept of a Humbucker pickup but with microphones instead of guitar pickups?

(And if so, will it actually make a difference? Is the perceived interference I'm getting actually from the microphones themselves, or another source such as wiring?)


texts: What kind of DC power supply has least noise

texts:
I operate an MEG system (extremely sensitive magnetic sensors for measuring brain activity) and I recently found that the DC power source that feeds into our magnetic shielded room (power used for moving the MEG/chair/bed - thus required), produces 60 Hz line noise detected by the sensors.  I'll detail my understanding the sources of this noise, but my question basically is: what kind of supply or what specific features should I look for to avoid this noise?

Noise from currents in wires.  The current supply is a typical cheap switched-mode floating DC supply, 24V 0.5A.  I did a few tests to confirm that although the difference between + and - looks "clean" and constant, each wire has a large voltage oscillation w.r.t. ground.  And this "voltage" seems to be the result of a current source, so even with no load, there will be an oscillation of charge density in the wires, enough to generate a magnetic field detected by our system.  (In the kOhm to MOhm range between + and G, I get on the order of 0.1 mA peak current.)
Noise from ground currents.  Unfortunately, if I tie the negative to ground, of course the oscillation w.r.t. ground is gone, and that mostly gets rid of the detected noise, but the "offending" current is not eliminated, instead going through the ground.  That also causes some noise, probably primarily because our shielded room is itself grounded.  Worth mentioning that this noise is much smaller.

Edit: Price is not a primary concern.  I realize a well designed low-noise supply would likely be much more expensive.


texts: How to link between different projects in Altium Designer?

texts: I am working on a project where we use many diffrent circuits and PCBs connected by a complex wiring harness. I would like to have a schematic of the wiring harness with sheet symbols representing the different circuits. The idea is to have the wire harness schematic as a logical overview of the system. We have each separate circuit in its own altium project, is there a way to link the sheet symbols to other projects? Or another way to merge them?


texts:
I'm designing for a very power sensitive motor controller, and I'm concerned about the power that will be lost to the ESR of my decoupling capacitors. I have a prototype board as well, but there's no way to tell how much energy is being wasted within the capacitors.

With the capacitors, I expect the current draw into the board to resemble a square wave, because it's a 3-phase BLDC motor. However, with all my nice decoupling, it's become a reasonably sinusoidal wave at my PWM frequency.

Is there any way to determine how much power is being wasted in these capacitors? All of the literature I can find on it seems to be overly complex white papers. Are there rules of thumb or first order approximations I can use?

Could I also perhaps remove the capacitors, capture voltage and current waveforms, and add them back and check the difference? This approach would tell me the results for the current design, but doesn't really help in the design process.

Thanks!


texts: Proper board layout for high power SMT FETs

texts:
I came across an SMT FET (IPT015N10N5ATMA1) that has an output of 300Amps in a rather small form factor. Are thermal vias enough to get heat away from the 8-PowerSFN package? Or would something like an Aluminum IMS board or something else be required?

I haven't dealt much with these current levels on a board, but if they make parts like this, what PCB design considerations need to be made to pull the most heat from this package?

It seems like a lot of heat to dissipate if operated near the max rating.


texts: L293 DC Motor Driver : How to set up PWM

texts:
So Im using a L293 H bridge driver, to manage a DC Motors Speed and Direction.
In every tutorial I see online people use the 1A and 2A inputs as the direction management inputs and the enable port as the Speed management, being the speed controlled by the PWM duty-Cycle.This should work because in the data sheet when EN=0 it is depicted as Free-Running motor Stop.
However my teacher explained it in class as using the 1A and 2A ports both connected to different PWM sources and with this control the direction and speed, like 50% 50% the motor is stopped and 60%40 % the motor goes in the direction of the 60%.
I've developed my whole project around the first option and my teacher doesn't really answer emails.
Is the first option really not viable or can use it?
I can't test this so im really just guessing now, because of quarantine we don't have the motors.I'm using a PIC32 to develop the code.
Thanks


texts: I only hear quzz when making a phone call using SIM800L module

texts: I made a board to make a phone call using SIM800L module. A PIC16F886 does the main roles, a PIC12F683 plays an audio message from a 24C256 EEPROM using PWM and sends it to SIM800L. The audio message is clear when I connect PIC12F683 PWM output to a speaker. The audio message is not clear but can be understood after making a phone call on a breadboard. But when I made the PCB I can hear only quzzzzzzzzzzzzzz on the other side after SIM800L make the call. What's the problem and ow can I solve it?I attached the photo of my PCB, and the circuit diagram.I also had a problem adjusting sound level before that is related to this project and is solved here.


texts:
I want to make an LED flash twice every ten seconds to the following character

*

  On 750ms approx, Off 1s , On 750ms approx, Off 7500ms, Repeat.

*

I am fully aware how to do this with a microcontroller but I do not want to go that route.
I was hoping to use 555 timers or similar. Is this possible?
Thanks folks


texts: Is .95J worth of work within 1 second Equivalent to .95W of Power?

texts:
This is a question that has two parts to it divided up into two sections. It is similar to the "Is Work done to Transfer Energy?" question but has been refined to include the conversion from Joules of work to it's equivalent Power and if they are indeed identical to one another.

The two circuit schematics are real world circuits with losses. Since there is resistance in the connecting wires, capacitor, inductor, diode, and switch the circuit is 95% efficient in the end and is far from perfect. The switch is manually closed and then opened by hand.

Only 1 cycle of energy transferred from C1 to C2 will be contemplated. In general the numbers and values in the circuit are arbitrary and may not be exact due to slight changes caused by resistance. Nevertheless everything will be kept as close as possible to what is actually known to be happening in the two circuits. The best effort is being taken to fashion the most accurate question.

At any one point where there are doubts of what is occurring there will be a short note about it to acknowledge it.

I am sure there will be some details that will be overlooked and brought up and possibly some nitpicking, (For instance is a Joule a unit of Work, Energy or both?). So this will have to be forgiven and possibly overlooked as it's insignificant, or not, to the final result and answer.

Section 1:
Down below is a simplistic schematic of a capacitor C1 intially charged with exactly 1J of energy. SW1 is closed for 1 second. This causes the 1J of energy to be transferred into L1 inductor's magnetic field to be temporarily stored. Work has been done to transfer the 1J of energy from the C1 capacitor to the L1 inductor's magnetic field. Because of the losses due to resistance, the C1 capacitor has done 0.95J worth of work on the inductor within 1 second of time.

(Note:) An attempt was made to match the inductance with the capacitance for a resonant frequency of 1 Hertz precisely which would translate to 1 second per cycle.

First half of Question:
What is the equivalent amount of power of the 0.95J worth of work that has occurred on the inductor within 1 second of time?

Section 2:
Next SW1 is opened after 1 second of time has passed. The 0.95J of energy that has been temporarily stored in the L1 inductor's magnetic field then collapses. The 0.95J of energy is then transferred from the L1 inductor's magnetic field through the D1 diode and then finally into capacitor C2 to be stored. The inductor has done 0.95J worth of work on C2. Capacitor C2 ends up with 19.43 V on it.

(Note:) It is realized the energy may have dropped again due to resistances. It is also realized that the amount of time it takes for this transfer of energy maybe considerably smaller than 1 second of time since it's a transient voltage spike, but possibly not since the C2 capacitor may or may not be acting as a load, which it is believed that it is.

Second half of Question:
What is the equivalent amount of power of the 0.95J worth of work that has occurred on the C2 capacitor within 1 second of time? Also what is the exact amount of time for this transfer of energy to occur?

From what is understood, power is the rate of work done and work is force x distance. Work has indeed been done because the energy has "moved" or "changed" during it's two transfers through the circuit. There is power because of the changing voltages and currents involved.


texts: What's the use of the teardrop shapes around some PCB pads?


texts: What is a feasable design goal for maximum clock frequency (related to setup timing) for a modern CPLD containing the attached circuit?

texts:
The CPLD is an Altera MAX V, with speed grade 5 (note that the MAX V comes with speed grades 4 and 5, where 4 is the faster one). The circuit consists of a 5-bit binary up counter where the count value is compared to a 5-bit input data value, and if the count value is greater-or-equal to the data value, then a flag is set.
This flag is used as an input to a small FSM. The FSM diagram and datapath circuit is shown in the attached figure

The max clock frequency design goal is 100 MHz, but via the TimeQuest timing analyzer tool in Altera Quartus, I get Fmax = 92 MHz.

Is the design goal to strict or should I normally be able to achieve this clocking frequency ?

Note that the clock frequency is based on setup timing considerations. There are no PLLs or internally generated clocks.

Also note that the failing paths (there are two) are between the count-value bits, q_1/q_0 and a bit for the state encoding: state2...


texts: Altium 18 - Problem when switching from Schematic to PCB

texts:
I have a rather odd problem when I switch from Schematic to PCB in Altium 18.
I go to the PCB file, I press the "Update PCB Document", then all is good, except for some components (test points) which is able to place them on the PCB, but is unable to connect them to nets.

The strange thing is that in both the schematic and the PCB file they are named TP1, TP2, etc, but in the window that appears after I press "Update PCB Document", they are written as TP1-1, TP2-1, etc. and of course I get an error that it cannot find the components (because they do not exist, TP1 exists, TP1-1 does not). Anyone has any idea what is causing this error, did I mess something up or should I contact support?


texts:
I have a design (Memoryintefacing module) with two processes as proposed by gaisler, one combinatorial process and one clocked to operate the registers. The whole entity generates a ready signal, which blocks the entities communiting with it. To not block them prematurely write access only generate a blocking signal if the entity is already busy processing a read or write. To allow for this the first state latches the supplied address and data, so a later write request won't overwrite the address half way through the process.

The problem I encounter in simulation is the following, in two consecutive cycles I request writes with different addresses. The first write starts fine, we are in the INITIAL state, the address is driven on the addressbus and the data and address are latched. The simulation of this clocks rising edge finishes and we go on to the next. Now the process for the statemachine is executed first. It sees the new address and latches the new address and drives it. Directly thereafter the register process triggers and updates the statemachines state. In the following delta cycle the statemachine jumps to the correct state not updating the latched data or the address driven. However my address driven and the latched value are screwed up already.

Is there any technic to achieve correct simulation results without a simulation considering register timing? Does my design still contain a major flaw (should I update my latch only at the clock edge in the register process)?


texts: What are some ways to use relays more efficiently?

texts: We often seem to use microcontrollers to control relays, and a 5 V microcontroller is often used with 12 V relays. A relay may need several times more power than the microcontroller. Not a problem if you can use an SSR, which you can drive at a few mA, but there are situations where you do need an electromechanical relay. When, is another discussion. Here I'll focus on the electromechanical. So, what are some ways to use those relays more efficiently?


texts: Why no macroscopic electrostatic electromechanical parts?

texts:
So, I understand that relays, motors, and other electromechanical devices are almost always electromagnetic devices. Why is this? I know that electrostatic motors exist, but what makes them substantially worse than electromagnetic motors?

Note that I'm asking specifically about macroscopic devices. I'm aware that electrostatic electromechanical devices are common in MEMS.


texts:
I am working on lithium ion batteries charging(NMC chemistry,  max charge voltage is 4.2).  In charging mode after cell reaching 4.2V,  charger is going to CV mode and after this Charge ends(based on cut off current).
As per my understand,  in CV mode battery chemistry stabilizes due to this we may get good capacity and life cycle.
What happens If we charge the battery to 4V(not up to 4.2) using CC mode and eliminating the CV mode this means we are not charging 100%(capacity not an issue in my application and i want to reduce the charge time).
Can we eliminate CV mode and use it? If use like this Any battery degradation/life cycle/capacity issues?
Please help me.


texts: Why do I need a resistor across VCC in this circuit?

texts:
I'm newer to electronics and am currently working on a project using a raspberry pi and a set of neopixels (WS2812) leds. I finally decided to get everything running off the same 5v power supply but was getting strange results almost like a pin was floating. After poking around with a multimeter I noticed that measuring voltage in one spot fixed the issue, so I added a resistor and my circuit works, only problem is I have no idea why it is working...

The resistor I added was between vcc in and the vcc pin on my 74ahct125 (logic shifter 3.3v to 5v). Any idea on why this is needed? I've modified the breadboard the tutorial I was following with my changes (running the pi off the same 5v and the resistor).


texts: Connect TFT LCD screen with flex band to breadboard

texts:
I'm asking for clues on how to do this, I didn't found much over the internet as everybody buys their LCD screens with a mounting to the breadboard of as a shield for arduino.

The TFT screen I bought is the following one:

http://www.ronboe.com/vdetail/405.html

As you can see, the connector is a flex band that is supposed to be soldered on a PCB, but there is no some kind of PCB with pin headers? what I want to do is to connect to a breadboard so I can use a raspberry pi to send data to it, I know there is other screens for the raspberry pi, but I need to use this screen to understand how it works and use it on further custom projects.

Any ideas or information to share?


texts: How to mount TO-92 package on a heatsink?

texts:
I want to measure heatsink temperature using LM35 TO-92 package. heatsink is a flat surface of aluminum.

What is the proper way of mounting a TO-92 temperature sensor on a heatsink so that can measure the temperature of the surface of heatsink and also not fall off easily?


texts: How are SMD thermal pads handled in Kicad's eeschema?

texts: I'm using Kicad to do a board with a MSOP-PowerPad which has a metal pad underneath the chip that should be soldered to the board. How are these thermal pads usually represented in eeschema?


texts: Need help with understanding PMDC Motors

texts:
I'm running out of places - and people - who have enough understanding of the questions I am asking. Please help!

I'm building a crab/shrimp pot puller. I've seen the regular production models and a few home built versions. What I don't understand is how a 12v PMDC 90:1 worm drive motor can be rated at 2.3hp. As far as I can tell, it looks to be the same motor I'm planning to use, and mine is a 12v 600w 60:1 worm drive that is rated at 0.8hp.

https://www.discoverybaymarinegear.com/cgi-bin/quikstore.pl?category=powerhauler

I'm told that my motor can be increased to 48v. Other than the 90:1 gearing, I don't see how they can claim a 140' per minute pull of a 200lb weight on a 90:1 ratio of a motor speed of 3600rpm,with a drive pulley of about 12". Doing the math:

3600/90:1 = 40rpm at the drive pulley. 1'(12") x 3.14 x 40rpm = 125.6' per minute ....without load. Is this even possible?

Can I create more HP if I increase the voltage to 24v? And if so, would increasing it to 48v give me the 2.3hp their motor claims to have. Can I do that with a 900w PMDC motor?

Moreover, is it even possible to create 2.3hp from a 12v supply, especially if the motor is in a 3" x 4.5" housing?

Is the 2.3hp a rating of the actual motor or what is coming off the drive shaft?

I installed my 12" (11" internal diameter) drive pulley on, turned the motor on, and I cannot stop it. I'm guessing this will be more than adequate, ...but feel I am missing something.

Thank you in advance.


texts: How to terminate unused transformer pins?

texts: What is the correct way to terminate/wire these unused transformer pins? Do they get tied to GND?


texts:
Where does the ALU's carry out go in this Shift-n-Add multiplier?
ex: what if my multiplicand is 0b10011 and the multiplier 0b10111
On the third shift I loose information because the A register is n-bits wide and I have a carry.

Any ideas if I'm doing something wrong?


texts: Derivation of LC impedance transformation formula

texts:
Apologies in advance for this esoteric question (and source).  I've been studying wideband LC oscillators recently and my search for an amplitude stabilized configuration led me to the Vackar Oscillator (wiki).

This document (published in 1949!) "LC Oscillators and their Frequency Stability" describes the circuit and I've been studying his analysis of a generic LC oscillator presented in the first few pages.

However, one crucial part of the analysis has me stumped.  If you look on page 4, derivation (5) you see this relation:

$$
V_{0}=V_{2}\sqrt{\frac{R_{d}}{Z_{{2}'}}}
$$

where

V0 is the voltage developed across the tuned circuit

V2 is the voltage developed across the input impedance to the tuned circuit

Rd is the dynamic resistance of the tuned circuit

Z2' is the input impedance of the tuned circuit

Vackar describes this formula as "the well-known impedance transformation".  But I can't find this relation described in any of my texts.  It looks vaguely similar to formulas related to tapped capacitors (and in particular how they behave as ideal transformers), but I'm not sure.

Can anyone provide a derivation of this formula?


texts: Low current input source - current limiting resistor for z-diode needed?

texts: I have a very low current input source (tiny solar cells) with a maximum short circuit current of 80µA which are loading a supercapacitor (1F/5.5V). To protect the supercapacitor from damage I added a z-diode with a value of 5.1V and 500mW. Since the output current of the solar cells is so low, can I ommit the current limiting resistor for this diode?


texts:
I got this NFC-Tag and I try to do something, so that this tag can't be recognized by any nfc-tag-reader anymore. But I want to easily change this state, so that I can easily 'free' the nfc-tag so that it is working again.

What would be the best solution for this?

I thought about aluminium or other metal to place on my nfc-tag. This would work, but is there any other solution for my problem, not using any metal?

I am not an electrical engineer, so maybe my quesion is kind of stupid, I can't evaluate.

EDIT: I don't want to use metal, because if I place it on my nfc-tag,  I can't see my tag anymore. Metal is very opaque. This is one of the reasons I am looking for different solutions.


texts: Bitstream autocorrelation? - comparing two bitstreams - BER?

texts:
I am sending a PN9 sequence from a sender to a receiver and want to compare the received bitstream (RB) to the sent one (SB). I am assuming that the transmission will get distorted and want to somehow correlate RB to SB in order to get a number which helps me to measure the distortion or the quality of the transmission or call it the bit error rate.
Hope I have made it clear. If not, please ask.
Any ideas or hints for me?

edit:

How would you compare both bit streams? On a PC?
I could imagine to redirect the stream from the receiver to a PC via UART.
If the PN9 which my sender generates is constant (that I assume as for now) the only question would be which tool to use in order to do the autocorrelation.
Any other ideas? Maybe on an oscilloscope (I doubt thats easily possible).


texts: Need help with calculation SPI Frequency

texts:
I am using Bit banging SPI to communicate with SDCard. I am using QCA4020 and I have no information regarding the Pin Toggling Frequency. To get the max speed of SPI Possible with the hardware I am generating clock by setting and resetting pin w/o any sort of delay in between.

I am taking the time before starting the communication and after ending the communication of 512 Bytes, and getting around 25600 Bytes per second from that calculation. I have to put down on paper a rough SPI Frequency that I am using for the communication and I have no tool to do it atm.

My calculations are

25600 Bytes per second ,

hence 25600*8 bits per second,

1 Bit change = 2 edge and hence 1 Clock.

therefore my speed comes to around 25600*8 = 204800 Hz.

Does that sound correct or do you suggest any other method to do so?

2) How is one supposed to get Bytes per second using the Pin Toggling Frequency?

My assumptions are :

Pin Toggling Frequency : 400000.
Hence Bytes per second will be 400000/8 = 50000.

Is it correct? or Am I missing something?

Does this hold true in terms of bitbanging as well?


texts: How does this capacitor work in this schematic?

texts:
So I'm looking at an AVR Programmers and setup and I see this schematic:

How exactly does this work? (Keep in mind I'm a newbie at schematics), but the way the schematic looks makes it seem like that a separate 22pF capacitor should go on each side. Is it because ceramic capacitors have no polarity, you can just put them in between? Am I missing something here or just being stupid? The schematic makes it seem like there should be 3 things where the one blue (what seems to be a capacitor is).


texts:
I am working on a design that requires 4 channels coming onto a PCB. The inputs are SMA connectors and are spaced 15mm apart from each other. These signals are routed with co-planar wave guides on the board to a SP4T RF switch. My operating frequency is 300Mhz - 900Mhz. The incoming signals have an amplitude range from -30dBm to 10dBm.

I am curious to know what kind of isolation can be expected in this situation. On my first experiment I was only able to obtain about 20dB of isolation between signals. From what I have read so far it seems that the best you can get is 40dB with a 2 layer board and a CPWG. Does anyone have any experience on how to improve this?

My next test board will involve all the connectors mounted so the signals are coming in at oblique angles to one another. However this does take up more space.


texts: Boat; How to charge Leisure batteries the first time?

texts:
I will have 4 x 12V 100ah leisure batteries for my boat. They will be wired in parallel(using staggered wiring). My alternator is 12V 50amps. The batteries will be charged when the boat is moving. Therefore, best case scenario dictates it will take at least 8 hours for the bank to charge (400/50amps).

The problem is I will not have the luxury of leaving the motor on for 8 hours when the batteries first arrive. At best I will have about 3 hours a day. They will also be used during that time.

The question is will I be seriously affecting the lifetime of my batteries by not charging them fully the first time they are used? Do brand new Marine Leisure batteries ever arrive fully charged?


texts:
I have an altera stratix iv FPGA, given to me by my professor to do a project that involves video processing.

The ports I have to work with are RS232 (female), an IDE port and several SATA ports, and several ethernet ports.

Can anyone recommend some good cameras for hooking up to the board for video?  I need a pretty high quality camera, but I'd like to keep it under $80.

Anything would be helpful, and thanks in advance!


texts: Design an AC/DC Nonisolated Switching Mode Power Supply

texts:
I'm designing a fifth generation pcb for my project and yet I stumbled across another design problem. First of all, the circuit and all components are enclosed from the environment and users (because non-isolated) for safety.

My design would rectify the mains (European 230V AC) to a DC voltage and after that some buck-switching controller would do the job. The only problem here is, that there aren't such IC's, that would accept the ~350V DC voltage. After looking at DC-DC Converters from LCSC, I knew there are those Switching Controllers, but after a while - all the datasheets feature an isolation transformer to step-down the voltage.

For the previous designs I was using the HLK-PM01 PSU, but that's wasting a lot of space.

I planning to use a non-isolated supply, because it doesn't require a custom transformer to build, just an inductor that I'll even find at LCSC.

Power output requirement: 5V at 150mA (maximum), to power an ATmega168P with some SPI/I2C chips.

In what direction should I search to find some information related to this kind of SMPS? I'll be really grateful for all advices I can get from others, more experienced engineers.


texts: How do you specify orientation of devices during PCB assembly

texts: Generally when I build stuff on a PCB I create a small legend with a circle for pin 1 and I use this to manually orient the IC. I was watching a couple of youtube videos on automated pick and place SMT assembly , and was curious as to whether there is any other file which specifies the orientation of the device. As far as I know I have only heard of gerbers and a BOM file. Is there an extra file which needs to be supplied to a PCB house for handling orientation for IC's as well as other devices(like tantalum capacitors etc)


texts: How to determine voltage/amps a circuit board expects

texts:
I'd like to add a new power supply to a board that came with 2xAAA batteries wired on. The issue is that the two batteries were connected on opposite ends of the board. I'd like my replacement power source to be a single battery pack or other power source and split the voltage using a jst splitter.

Open questions:

Is this even feasible with a jst splitter?
How much voltage/amps should I be supplying so that it matches the two AAA batteries going individually into the board.

I tried to use two AAA batteries in series to power the board but it seemed to not be enough power (or just didn't produce anything noticeable).

Edits with more info:

JST splitter being used: https://www.amazon.com/VIMVIP-Pieces-Splitter-Female-Connector/dp/B01DXYWNGS
Screenshot of board being used: http://prntscr.com/mgp5d0 (leads connected to Bat+/-)
Board being used was ripped from Chemion glasses: https://www.chemionglasses.com/learn-more/

I have successfully made the board turn on if I attach a pack of 4xAA batteries to the board but it starts to overheat, so that isn't the answer of course.


texts: Logging and retrieving large bursts of sensor data from an Arduino

texts:
I was wondering, if I put an Arduino with a few sensors on let's say a water rocket to track acceleration and height and what not, how would I save this data?
I'm assuming that I want to have a high resolution in my data, so let's say I take a measurement from every sensor every 10ms.
I'm figuring this might be too much to write on a SD card that fast.
The Arduino is obviously not connected via USB, so wired serial monitor doesn't work. I could have a wireless serial output and log the data on a laptop receiving the serial monitor.
Another way I know would be something like MQTT over WiFi - but is it made to handle this much data in a short time?
How would you do it?


texts: SOPs for converting a digital circuit from 5V to 3.3V

texts:
I am in the middle of an exercise in which I have to upgrade an old motor driver circuit. The old circuit has an MCU and all its logic based on Vdd=5V. I have to use a new MCU whose Vdd=3.3V. So now I have to change the rest of the circuit to 3.3V also. I wonder if there are any suggestions advices or SOPs for such an exercise?

Is it advisable that both power supplies co-exist in a circuit?


texts: Voltage graph of capacitor with AC source

texts: below is the 'Dickson's charge pump'. What I want to know is that when clk is on, why does Vx is 3v instead of 1v? I just thought Vin contribute 2v to cap, clk contribute 1v to cap, so 2v - 1v = 1v but it isn't. Could you explain this?


texts: Flat connectors and flexible cables for a glove-mounted LED strip?

texts:
About a year ago made a LED-studded glove from flexible LED strip (like https://www.sparkfun.com/products/12027 but without the silicon coating) for a party.

Because I wanted to keep some mobility in the hand, I cut the strip into smaller segments and soldered some ribbon cable in between with some flexing capability.

This worked for about half an hour, but then the connections started breaking. The solder joints themselves were fine, but the teeny-weeny stranded wires in the ribbon cable broke because of the strain. Taking the glove off broke several in one go.

Now I'd like to make a v.2 that would survive slightly longer. I'd also like to avoid soldering all the connections again because there are over a hundred connections to be made. Obviously, stress reduction is key.

If there was some very flat (1-2 mm) connector that I could just clamp on the of the LED strip and a suitable interconnect cable, that would be optimal. But I have no idea what to look for.

(I'm also open to better suggestions on how to implement the connections. I've considered conducting thread but the shortcut risk is too high)

EDIT: Turns out there are such connectors: http://www.aliexpress.com/store/product/free-shipping-10mm-4pin-for-5050-RGB-led-strip-light-LED-Connector/1027020_1544738051.html

Unfortunately I've only found the 2-pin and 4-pin variants, whereas my LED strip has 3 pads.


texts:
I am totally new to hardware.

Recently I bought this MQ-2 module, but I couldn't figure how to get it to work, the on the ship worked but where is the output? I mean the place where I place the voltmeter?

This is a picture of it:

It has 5 connections (+5v, GND, NO, COM, NC ).


texts: Regulated multi-voltage PSU given a center-tapped transformer and a single regulator/zener

texts:
My first post here, sorry in advance if this question has already been covered. Being a computer scientist, my knowledge about electronics is limited, never had a formal education, a couple of courses when i was a student hardly qualify me as an electronic engineer, so please forgive me again if this question might appear basic (it probably is).
I am currently designing a simple regulated power supply given a center tapped transformer (lets assume a 3.15V-0-3.15V @ 5A secondary) and a SINGLE regulator.

So, having a bridge rectifier + filter caps i assume:

A somewhere in the region of 4.4415V with respect to GND
B somewhere in the region of -4.4415V with respect to GND

Now, lets assume the application calls for a) a specific voltage of 6.3V to power vintage tube filaments (DC, regulated, C-D) and b) 5V to power a simple MCU (E-F) from the same transformer winding.
Given the schematic (assume a TO-220 7806 as a regulator on a heatsink, 1n5817 schottky and a 5.1V zener), obviously, it has to be B=D=F, therefore i assume all to be at -4.4415V, right ?
In my case, there is actually no need for a negative voltage, is there a cheap/simple way (without introducing additional silicon, PCB space is an issue :-)) to elevate the negative rail (B/D/F) to GND while still being able to provide 6.3VDC between C and D (other than dropping the center tap) ?
Thank you very much in advance, regards
EDIT: numbers + concrete case description
EDIT: Having considered posted suggestions (thanks to @fraxinus, @Marcus Müller for pointing out that the transformers voltage is too low for a decent regulation), i came up with an update that i hope to suffice for my application (see image).


texts: Anyone knows what software tool is used to draw these circuit schematics

texts:
I was reading online and found this site: http://www.cppsim.com/

I was very curious how this professor drew all these circuit diagrams in his lecture notes (such as this one: http://www.cppsim.com/CommCircuitLectures/lec9.pdf). They just look very very good.

And example is shown below:

To be more specific about what I mean, by "publication quality" I mean the following:

The software must output vector graphics, such as eps, or windows meta files.
It would be good to have control over the style of the graphics, such the style of the components, line width, figure size, etc.
It would be good to have a graphical user interface. I understand LaTeX is very powerful but it's just too painful to write a 100 line script to generate a circuit diagram.

So in short, I'm not really looking for a schematic capture program. I'm looking for a program that can generate pretty circuit schematic illustrations so that I can put them in papers and presentations.

(I am aware of other posts on this forum, such as this one: Good tools for drawing schematics.  None of the software mentioned in that post seems to get you publication quality figures.)


texts: Create repeated pole/zero in transfer function---Octave

texts:
Say I have such a transfer function with a repeated zero

$$ \frac{s^2}{s+2} $$

How do I enter this in Octave as a transfer function? Perhaps this question applies to Matlab as well. If the zero was not repeated, I would have typed

numerator=[1 0]
denominator=[1 2]
sys=tf(numerator,denominator)

to form the system as a transfer function.


texts:
The question was to find the equivalent resistance between A and B. The correct answer is R. I too arrived at R by considering the ends of the lowest two wires equi-potent because the lowest wire has 0 resistance (and so according to V=IR, V comes out to be 0) and redrawing the circuit by taking the equi-potent points as a single point. But then when i was again inspecting the circuit, it seemed to me that the lowest two wires are connected in parallel which would make the equivalent resistance across their ends 0 since r1=rr'/(r+r') and thus the equivalent resistance between A and B comes out to be R/2. I think this is certainly not the case since the correct answer is R. So are the lowest two wires connected in parallel(which is probably not the case and if not then why?

Edit: I would like to know how to proceed if the bottom wire also has a resistor of resistance R. I am unable to simplify the circuit for this.


texts: How to test TS7805 regulator if it is working?

texts:
I have a TS7805 voltage regulator that was placed on a pcb, laying around for 2 yeras. Is there a fast way to see if it is still working? I have a multimeter and some resistors at home and an DC 5-12V Adapter.

Thanks!


texts:
I am trying to simulate this circuit i want to know if the circuit i assembled is correct?

i want the current of VCCS element 1 and 2 plotted on a graph as i vary Vtun, Vsprog and Vdprog. I am using the following code is this correct?

CCapacitor_1 N_3 N_1  250f
RResistor_1 Vsprog N_4  R=500
MPMOS_1 N_3 N_1 N_2 Gnd PMOS W=2.5u L=250n AS=2.25p PS=6.8u AD=2.25p PD=6.8u
MPMOS_2 Vtun N_1 Vtun Gnd PMOS W=2.5u L=250n AS=2.25p PS=6.8u AD=2.25p PD=6.8u
MPMOS_3 N_4 N_1 Vdprog Gnd PMOS W=2.5u L=250n AS=2.25p PS=6.8u AD=2.25p PD=6.8u
GVCCS_G_Element_1 Vtun N_1 Vtun N_1  0.1
GVCCS_G_Element_2 N_1 Vsprog Vsprog N_1 0.1

v1 Vtun Gnd dc 0.01
v2 Vsprog Gnd dc 0.03
v3 Vdprog Gnd dc 0.02
.tran 1 10n
.print I(v1) I(v2) I(v3)


texts: How is a latch different from Schmitt Trigger?

texts:
Consider a simple latch (two cross coupled inverters). The positive feedback makes the circuit operate in either of the two stable states if the overall gain is greater than unity. If there is a trigger that pushes the operating point beyond the switching point or pulls it down below the point, the output changes its state. Is the only difference between this and a schmitt trigger is that there are two trigger points in a schmitt trigger?

How do these circuits differ in operation in terms of positive feedback?


texts: Is it possible to run three phase motor with single phase supply? How?

texts: I have rubber mixer machine that motor need three phase supply. Unfortunately I only have single phase supply. I heard a rumor that three phase motor can be run with single phase supply. So, pls guy here help me out of this problem. Your answer is so greatful in advance.


texts: What do the numbers mean on a three-position switch?

texts:
I'm having trouble understanding how this instrument switch works.

Here is the schematic illustrating the three switch states:

How do I interpret these numbers?

If I were to guess, I'd say that the two relays are shown in the open position (NVG):

On closes the top relay:

Off closes the bottom relay:

I don't have any confidence in my guess though.

Also, I don't understand why there are two junctions not connected to anything:

Hopefully this is standardized, and not specific to my wiring diagram.
I couldn't find the numbers referenced anywhere on the sheet.


texts:
Attempting to drive the stepper but noticed that the motor is rated for 3V 2A and both of these boards feature a motor driving voltage of 6-30V or 7-30V

Attempting to drive a Wantai 57BYGH420-2 Stepper motor.
I have these drivers at my disposal :
Easy A3967 Stepper Motor Driver Development Board and
Big Easy Driver board v1.2 A4988 stepper motor driver board.

Can this be done while not damaging by stepper?

Stepper


texts: How can I store audio files in the uC ROM so as to serially transmit it to a decoder chip?

texts:
I am using an NXP micro controller (P89V51RD2) with on board flash of 64kB. I want to interface it with an audio decoder IC, probably VS1011 (if I can get the IC). What should I do to use on board ROM to store the audio files, so that I can serially transmit them using SBUF to the decoder.

I tried incorporating a .amr of 8kB file recorded from my mobile but it was unsuccessful.

I used this code :

xdata char mp3[]={
#include"one.amr"
};

I saw this question but the answer gives pre-built projects.

Also, I have trouble getting any of the VS10xx series so any alternative ICs which provide same functionality are welcome.


texts: Could static electricity from trading card binder pages damage SMD components?

texts:
I bought a trading card binder to hold SMD components.  I chose it because its card-sized sleeves can hold more than just tape strips and also it has a zipper.   However my concern is that the clear plastic sleeves generate a little static and I am wondering if it could damage components.  The binder would contain resistors, capacitors, LEDs, diodes, MOSFETs, different ICs including MCUs, and random SMD jacks and buttons.
The static is minimal; it just slightly attracts your arm hair if you put your arm close, but the pages don't stick together or make any staticky crackling sound when you flip through them.  Also the components will always be in their paper or plastic tape within the sleeve.
Could this type of static hurt any of the components I listed (especially the MOSFETs or ICs)?  I've learned not to assume things, so I figured I'd ask before I fill this thing with hundred of components.  I know I could get a binder tailor-made for SMD stuff, but I just couldn't find exactly what I was looking for in that field.


texts: How might this RF double pole switch be constructed and perform?

texts:
So I'm aware that there are some high speed RF SPDT switches e.g. Single-Pole Double-Throw (SPDT) switch offering 20nS switching time. I'm interested in a switch like the following picture. This is related to a wireless scheme called Generalized Spatial Modulation.

Basically, I'm wondering how such a switch is constructed (can we make it from SPDT switches)?

Note here that the poles can connect to any of the antennas (however the case where two poles connect to the same antenna would not be used in practice.)


texts: Is it a routed slot the same than creepage concept and how to calculate slot width?

texts:
I was reading a high voltage pcb design guide and it talks about insulators insertions, routed slots, gradient rings, etc.. but it doesn't talk about creepage. As the creepage could be achieved by inserting a barrier or even be a hole on the PCB, here is my confussion.

Talking with my pcb manufacturer he also makes difference between creepage and routed slots close to the conductor pads.

He said that hole width must be calculated depending on the required voltage between pads to protect from arching. I know how to calculate distances for clearance and creepage. But if slots must be calculated I don't know how to do it. I didn' t find any information about routed slots like the pict. So, I hope someone here could tell me how to do it.


texts: I am trying to figure out the loss from a cable splitter. I am assuming it is analyzing any other filter circuit. This should equals a loss by a factor of 1.5 or is there some special nomenclature for splitters?


texts: What does the 'watt' specified for a motor mean?

texts:
What does the watts specification on a motor mean?

For example, there are motors with "power: 1500 watts" written on them. Does this mean that motor is capable of output power of 1500 watts?

And what is an 'LBC 05' series motor?

And if I wanted to drive two wheels of a car (x kg car) what are the factors that I will need to keep in mind while selecting the motor? Does the car weight matter?

Thank you. I am a newbie to this and trying to build an electric car :) Any help will be appreciated.
 EDIT : P.s Please what are poles of a motor ?


texts: Ballpark achievable switching frequency for 100mW D-class amplifier

texts:
The background for this question is a Master level university group project, we're designing a class D sigma delta modulated amplifier which is part of a MIDI synthesizer on a large FPGA.

We're currently attempting to reach 12 bits of performance at  20hz - 20khz final output frequency at over 80% percent power efficiency. Currently we are deciding between trading off output frequency and required noise shaping loop order (2 or 3rd degree).

Now, the issue at hand is inexperience estimating how fast we can drive our external output switches (directly or with drivers). A second order loop would theoretically call for oversampling of 40x ish, to reach 12 bit performance. Which means driving the switches at a frequency of 1.6 Mhz.

Third order loop would bring this down to 960 khz or so at the expense of extra complexity and loop stability considerations.

Exploring high performance mosfets in the ~500mA capability area and low gate charge they seem to have rise and fall times around 5-10ns and turn-off/on delay times of order 10-20ns. Assuming a 1.6Mhz output frequency it means transition times are seemingly creeping up to 5-15% of the period.

What switching frequencies can we expect to reasonably achieve for 50-100mW power delivery either entirely discretely or with the help of mosfet drivers. If necessary we can fabricate a pcb with smd parts and proper layout ?


texts: Calcuation of Gain // Instrumentation amplifier

texts:
I am using an instrumentation amplifier for my project .
The differential signal applied to amplifier through sensor is 0-2mV

i was wondering if i replace 2k2(R5) resistor with a 5k pot ...would i be able to achieve a gain of 1000
i.e i want the output of this circuit to be 0-2 Volts .

p.s. i cannot use the instrumentation amplifiers like ad620...due to some reasons...
Thank you .


texts: Do you know what this connector is called?

texts:
It connects a GPS antenna to the PCB with the receiver and other components. The device was accidentally dropped, and this connector seems to have been damaged because it doesn't mate properly with the receptacle anymore. Is it possible to cut it off and replace?

Cheers!


texts: Basic code to switch LED for PIC18f4550 XC8 not working!

texts:
I can't run this code on my PIC18F4550 with 20.00 MHz crystal oscillator. I use XC8 compiler. Where is the problem? How to write a configuration in XC8 compiler? By the way I am a beginner in the microcontroller world. Can someone tell me what is wrong with my configuration?

#pragma config OSC = HS,OSCS = OFF
#pragma config PWRT = OFF,BOR = ON,BOVR = 45
#pragma config WDT = OFF,LVP = OFF
#pragma config DEBUG = OFF,STVR = OFF
#include<p18f4550.h>

void msdelay(unsigned int ms)
{
    unsingned int x;
    unsigned char z;
    for(x = 0; x < ms ; x++)
        for(z = 0; z < 165;z++);
}

void main(void)
{
    TRISB = 0;
    while(1)
    {
        PORTB = 0x55;
        msdelay(500);
        PORTB = 0xAA;
        msdelay(500);
    }
}


texts: Time relay with external impulse trigger

texts:
I have garage door opener which I want to use to control external light during closing or opening.
This is how my output looks like at door motor:

In order to achieve light control I have remote switch in my light and remote relay connected to motor. Now the question is when to detect if door is opening or closing. For this purpose I can use Flash output( as a trigger signal) which is supposed to be used by blinking alarm light. But the thing is I don't want my external light to blink but to being turned on constantly.
To solve this problem I've decided to use this time relay which will convert blinking signal to constant one.
According to this picture as a trigger signal I can connect anything +/-, L/N

So I set proper mode which is:

And connected everything as follows:

But it doesn't work. I was playing with this relay a bit and it turned out that it is not triggering when I connect red line to +24V but it does when I connect it to the GND
What am I doing wrong?
Why rising or trailing edge is working with ground and not positive?
UPDATE
Manual in english for similar relay - 230V AC only instead of 24V AC/DC
This is connection diagram from manual:


texts:
So I'm getting ready to build a power supply, and it calls for a bridge rectifier. However, I can't find any information about HOW rectifiers are rated, except for a note that (and I don't have it in front of me) reverse voltage should be three times normal to protect against spikes...or some such.

My input voltage is 110VAC, with a transformer converting it to 18VDC/1A.

Is the rectifier voltage the MAXIMUM it can take? or something else?
What about amperage? Same deal? or, in my instance, do I need to have a 1A rectifier?

I have a choice between a 35V/10A, 50V/2A and 60V/4A rectifier, and I'm leaning toward the 60V/4A, guided ONLY by the fact that it's the only one that meets the 18V*3 note that I read.

Will I encounter a blue smoke demon? or is this a good way of thinking about it? How do I interpret rectifier ratings against a schematic when there's no specification beyond "bridge rectifier" in the parts list?

Crappy camera phone image. If it's illegible let me know, I can upload a scan in a couple hours.


texts: How to fix electric piano circuit board tracks?

texts:
Hi I am new so please be gentle.
I have AP80R electric Piano with some keys which are intermittent.
I have opened it up and it appears that the board has some signs of corrosion.

I have cleaned it and would appreciate next steps.
Whether broken tracks can be repaired by applying conductive glue?
how to identify where faults are?

I have attached a photo

Thank you

Pit


texts: It takes longer for a BJT device to come out of saturation than a MOS device to come out of triode region. It is explained by the base charge storage time, the charge has to recombine and go back to emitter and collector at the same time. Isn't this the case for MOS devices too? The charge in the channel has to go back to source and drain. What is the cause of BJTs being slower to come out of saturation than MOSFETs?


texts: How to find out the maximum current across a voltage source(using a DMM)?

texts:
I have an old Nokia phone charger lying around which I want to adapt for powering my breadboard/PCBs.

I was trying to find out how much current the charger was able to supply, so I connected a DMM across its leads and measured the current.

Now, I know that one is not supposed to measure a battery/power supply current by just connecting the leads (since the ammeter setting in a DMM effectively shorts out the battery/power supply) but use a load, what other method is there to measure maximum current?

Do I just use a small resistor(like a 10 ohm one) in series? I'm worried that that'll burn up the resistor and/or give a wrong reading.

I also have a USB cable that I could use with my current phone charger
to power the breadboard, but as asked earlier - is there a risk of damage to the charger/DMM by directly measuring the current?


texts: How do I use TABLE with ngspice correctly?

texts:
I am trying to plot the output characteristic of a power mosfet model in ngspice. Let's assume the following simplified example script:
MOS OUTPUT CHARACTERISTICS
Vindex index 0
Eds d 0 TABLE {V(index)} = (0, 2.5) (1, 5) (2, 2.5) (3, 5)
Egs g 0 TABLE {V(index)} = (0, 5) (1, 5) (2, 10) (3, 10)
M1 d g 0 MOS1
.MODEL MOS1 VDMOS Nchan Vds=200 VTO=-4 KP=10 Lambda=5m
.DC Vindex 0 3 1
.END

This results in the following error:
Circuit: mos output characteristics

Error on line 0 :
  aeds %v(eds_int2) %v(eds_int1) xfer_eds
 MIF-ERROR - unable to find definition of model xfer_eds
    Simulation interrupted due to error!

I am stumped what I am doing wrong here. If I use B-sources with pwl the whole thing works flawlessly:
MOS OUTPUT CHARACTERISTICS
Vindex index 0
Bds d 0 V = pwl(v(index), 0, 2.5, 1, 5, 2, 2.5, 3, 5)
Bgs g 0 V = pwl(v(index), 0, 5, 1, 5, 2, 10, 3, 10)
M1 d g 0 MOS1
.MODEL MOS1 VDMOS Nchan Vds=200 VTO=-4 KP=10 Lambda=5m
.DC Vindex 0 3 1
.END


texts: Which type of capacitor to use for matching the data sheet?

texts:
I want to choose decoupling capacitors for some microcontroller peripherals, which in their data sheets only specify some capacitans. Since you have quite a choice of passive components and the data sheets not always specify which type to use (ceramic, some electrolytic, aluminum or tantalum) I feel insecure.

The data sheet says to use a 1uF and a 0.1uF cap. I feel sure that the 0.1uF one could be a ceramic. But could the 1uF be one to? I want to operate at 3.3V will a 1uF ceramic cap lose to much capacity to make the recommended 1uF. And is a 0402 cap as good as a 0603 for the same capacity?

Thank you for any help!


texts: How do you create a variable load on something like a wind turbine?

texts:
Looking over how wind turbine controllers work, it looks like they use something called "Maximum power point tracking", or "MPPT".

As I understand it, that involves changing the load on the wind turbine to extract more or less energy, and thus control the speed. I'm presuming that you could also use that to electrically brake your wind turbine.

How would you control the load from a microcontroller?


texts: Measuring small currents at DC high voltages without floating meter

texts:
I'm doing a project with a Cockcroft-Walton multiplier that will output up to 40 kV  DC at up to 10 mA. The the circuit takes an input of 10 kV AC at 60 mA and 60 Hz (from a neon sign transformer) and passes it through a two-stage full wave Cockcroft-Walton multiplier with 50 nF capacitors.

I'd like see the current waveform my load is drawing, and due to the nature of what it's powering (a fusor), it's not possible to measure the current to ground. It might be possible to measure the AC current at the neon sign transformer (or before the neon sign transformer) but I fear the current waveform could be "mangled" if I measure before the Cockcroft-Walton. the voltage droop of the multiplier is also nonlinear, so I can't just measure the output voltage and calculate the output current.

Normally, I would just add a 100Ω resistor to the output of the Cockcroft-Walton, and measure the voltage drop across the resistor (since a voltage drop of 1V would correspond to a current of 10 mA), which I would then feed into an Arduino.

But there's my problem - to make this work, I'd have to let the Arduino's internal ground float to the ~40 kV of the output, which makes it really hard to power and read data from it. While I could power the Arduino with a battery and read data from it over Bluetooth, this is a pretty gross solution. I also thought about using an op-amp, but I don't think any op-amp could survive a 40 kV difference between its inputs and its outputs.

So my question is this: How can I measure the current waveform being supplied by my Cockcroft-Walton multiplier in a way that can be read by an Arduino at ground?

Edit: Added more details about the Cockcroft-Walton specifications


texts: What are capacitive and inductive thermo sensors?

texts: My boss talked about those sensors today. I have no experience with either of them. Can someone please explain the theory and advantages/disadvantages of each type?


texts: Can single phase AC produce a continuous electric arc?

texts: Constant DC supply and 3 phase AC (in mercury rectifier) can produce a continuous arc. But can single phase AC also produce a continuous arc? Because it is written on the web that arc extinguishes at zero crossing. Also high voltage is needed to initiate arc. But what is needed to maintain the arc (high voltage or high current)?


texts: Do PCB fabrication houses bootload/upload firmware?

texts:
Lets say for example, if I were to produce 500 Arduino based circuit boards and were going to have them fabricated and assembled by a fab house, do they usually offer a service to bootload the boards or upload code to them before sending them to me?

If so, what is the process called?


texts:
I have read that delay fuses are ideal for electric elements that require an additional start-up current like electric motors.

I am using several servos to drive a pretty heavy mechanical structure. Each servo has one of its cables connected to a fuse socket.

Should I use delay fuses or quick fuses (standard) to protect the servo motors from an overload, possibly a short-circuit? How quickly are delay fuses generally triggered?


texts:
I was able to get dwelche's blinker01 example to work fine; thanks yet again Old Timer!

I headed over to the reference manual to trace through how that code works, and it's easy enough to follow.

1) Enabling Port C using bit 4 on the RCC_APB2ENR register
2) Set bits 21 and 20 of the GPIO_c_CRH to 01 (output max 10Mhz)
2.1) GPIO_c_CRH is 0x4001 1000 GPIO Port C + 0x04 offset
3) Sets bits 23 and 22 to 00 for push-pull output
4) ...you get the point

The trouble I am having is probably a super simple thing from lack of experience:

I could not find out why port C is the one that's enabled? The Pin is called PC13, and there are other pins: PA3 or PB15.  Would I then enable Ports A and B for those pins?

Why then are there A through G?  I also had trouble figuring out the Alternate Functions for this MCU.  My experience with AF's is only from the Raspberry Pi.


texts:
Do all LEDs have the same optical power vs current curve?
(NOTE:  Thanks to  some guidance and patience from some patons of EESE, not to mention my naieve/unfortunate/inaccurate word choice in the original version of this question,  I have been able to condense it down to just a single sentence.  As such, it takes away the context under which the two answers were given.  For example, the answers mention "an indicator LED" and a situation where I "replace an old (indicator) LED with a modern one".  Rather than rewrite this question from square one so as to maintain context and express a coherent question (assuming I could even do this),  I have decided to take the advice given to me and ask the question that best solves my problem.  But since I didn't want to ignore the help I had getting what I came here for, I thought I should write this note.  As far as context (for the theoretical reader who might be wondering), I realized that this now-viable question doesn't supress the context , it has found it a nice home: in the edit history.)


texts: Why don't we consider the voltage drop due to inductance of conductors in dc motors?

texts:
In a dc motor, V = Eb + Ia.Ra

why don't we add the effect of inductance of coils.


texts: Delta wye transformer, voltages explanation?

texts:
So I'm doing a delta wye transformer simulation in simulink, and I need some
clarification about transformer voltages.
Here's a image from a youtube video

We have phase voltages on primary that are 4160 V, but we also have Voltage A to ground, B to ground and C to ground which is 2400 V.

And on the secondary side when we will look for a phase shift we are going to look for a to ground, b to ground, and a to ground voltages that are 480 V.

So my question is when we have a transformer (delta-wye) for example 220kV/110kV, so primary voltage is 220kV, but what voltage is it, voltage A to ground(VAG in video) or phase A (VAB)?


texts: How to calculate open-loop input impedance of an opamp if it is not explicitly given in the datasheet?

texts:
I would like to know input impedance of opamps I'm using in the circuit, so that I can choose input stage resistors optimally. However, opamp datasheets usually don't give the imput impedance value explicitly.
(Examples: LMV321, OPA330)
How do I calculate input impedance in case it is not given in the datasheet?


texts: Controlling 7W 12-14V power LED with Arduino

texts: I'm trying to control a 7W 560MA 12-14V COB LED Strip using Arduino. When I connect the LED directly to a power supply at 14V (using 1 ohm limiting resistor) I have 0.56A / 12.3V on my LED. But if I connect it through TIP120 transistor to control it by Arduino (using 14V power supply) I have only 0.38A / 11.7V on my LED. So I have a significant drop of LED power. Did I choose the wrong transistor? If so, please help me to choose the right one.


texts: How to improve the current when the voltage is high in solar cell?

texts: I am doing research on the fabrication of natural dye sensitized solar cells. The electrodes were imported . The dye was prepared from fruits and leaves using DMSO as solvent and KI and I2 in acetonitrile is used as electrolyte. When operated the potential (Voc) gradually builds upto 400 mV in 10 to 15 sec. When short circuit the current (Jsc) IS only 10 microampere. Kindly suggest how to improve the current ?


texts: How can I calculate the voltage on the load with an UNUN (unbalanced-to-unbalanced) RF transformer?

texts:
I'm having hard time calculating how much RF voltage would be applied to the load in presence of an RF transformer (Unun with a specific ratio).
Let me draw a simple circuit diagram. The AC power source is at the leftmost and its output impedance is (as normally) set to 50 Ohm. There is a load with an impedance \$Z_L > 50\$ Ohm at the other side. Therefore, the unbalanced-to-unbalanced (UNUN) RF transformer with a winding ratio \$n\$ is installed between them to match the impedance. The output impedance of the UNUN would be equal to \$ 50 \times n^2 \$ (for example, 450 Ohm when \$ n = 3 \$).

I was trying to approach this problem as following.
Let \$P_0\$ the incident AC power generated from the source. If the UNUN output is not exactly the same with the load impedance \$Z_L\$, then some portion of the power should be reflected back. That is expressed by the reflection coefficient,
$$ \Gamma = \frac{Z_L - Z_0}{Z_L + Z_0}, $$
where \$ Z_0 = 50 n^2\$ is the output impedance of the UNUN transformer (without the transformer, it is just 50 Ohm).
Thus the reflected and transmitted power are given by
$$ P_r = \Gamma^2 P_0, \qquad P_t = P_0 - P_r = (1-\Gamma^2)P_0. $$
At the same time, the relation between the transmitted power and the (rms) voltage on the load is
$$ P_t = \frac{V_{L, rms}^2}{Z_L}$$
Therefore, the voltage applied on the load should be
$$ V_{L, rms} = \sqrt{(1-\Gamma^2)P_0 Z_L}. $$
My question is following. Is the above calculation and reasoning are correct? If it's wrong, what is the correct way to evaluate the voltage applied on the load?
And my second question is, how should I evaluate the voltage applied to the loads \$Z_L\$ and \$Z_L'\$ in the following figure, where the power source output is splitted into two and each of them goes to a UNUN transformer respectively where the ratios \$n, m\$ are not necessarily the same.

In the second example, what happens if the three ports of the splitter are perfectly symmetric (so that no difference between inputs and outputs), so that a (reflected) current can flow bidirectionally the upper and lower parts back and forth?
Please enlighten me. Thank you in advance!


texts: How can this negative voltage spikes be explained?

texts:
I'm tried to understand capacity measurement circuity. A basic method is to load a capacitor with a constant current and show how long it took to reach 50% voltage for example. Capacity = (Current * delta T) / Voltage

Basic Circuity:

simulate this circuit – Schematic created using CircuitLab

The image shows the start/end of the charging, and decharging through Q1. After 245µs (after the capacitor voltage is 0V for several µs) charging starts again. What I can not explain is the sudden negative voltage spike when the decharging transistor is turned off (245µs).

Can some one explain that? Could this only be a simulation problem (LTSpice)?

I replaced the transistor with a "voltage controlled switch" (SW) and there was no spike at all.

The current source is a 2 transistor current source (1.5µA).


texts: What is the difference between operating voltage and output voltage in power electronics?

texts:
I am currently working on the topic of multilevel inverters.  When I started studying about it I came across the term operating voltage. When I went to search about it I got this doubt that whether these two terms are same or different.
I searched in the internet but couldn't find it.
Is operating and output voltage related to the same meaning or are they different?


texts: High voltage and cheap differential amplifier

texts:
Can I use a LM324N (very common) op-amp to act as a high-side differential current sense op amp at high voltage?

The Differential Amplifier

The differential input voltage rating is 32v, but my load supply is up to 80v. I have found more expensive current sense ICs that have input protection up to 500v, but I like the 324 because it's super cheap and comes in quad packages.

The actual voltage across the amplifier's inputs will not exceed very small values during sensing, and technically the two terminals of the 1mOhm sense resistor should never have more than 32v differential potential between them, but when idle, the high side resistor may have a difference of 80ish volts between the negative supply (GND) and the inputs.

Will this blow out the opamp? If so, can I use some clever diode protection trick to keep the opamp input voltage down?


texts: Difference between types of 433 Mhz RF modules

texts:
1) I am working on a problem, the emulation of which requires me to setup a wireless mesh network with various nodes.

2) A node is a collection on an Arduino Uno board with a 433 MHz Transreceiver modules. (I received a partial setup on my taking over of the problem).

3) In order to expand the network, I wanted to buy some additional RF modules so I stumbled across these types

A. https://www.amazon.com/433Mhz-Transmitter-Receiver-Link-Arduino/dp/B016V18KZ8/ref=sr_1_2?ie=UTF8&qid=1470286538&sr=8-2&keywords=433+RF+module (Call it the 4 pin receiver, say)

B. https://www.amazon.com/Geeetech-433Mhz-Transmitter-Receiver-Experiment/dp/B00AMB3NCY/ref=sr_1_14?ie=UTF8&qid=1470286606&sr=8-14&keywords=RF+module (Call it the 8 pin receiver, say)

4) The setup I had, had the B type RF modules working perfectly fine.

5) I then got a few more type A's thinking they would work but what I realised that the receiver modules of the type A's weren't as fast as receiving closely spaced transmission (100ms apart). On increasing the gap to about 800ms they worked fine. I checked this on all 4 that I got just to make sure that there wasn't a hardware fault in any.

6) The transmitters however worked okay.

So my question is, is there a fundamental difference between the two types, or was my experience due to the specific product that i received (implying a different manufacturers' product would possibly may have given me desired result)??

Thanks


texts:
I just have a few general questions that those with more experience could easily answer.

I am working with an arduino, and interfacing with various devices such as the PC that I use to write the arduino C code, which is obviously plugged in via USB, and I have had success with a serial link to an iphone by connecting the tx/rx pins.

What sort of data integrity guarantees are there for the serial link? For example if the cable connecting two devices becomes frayed or damaged, what sort of changes might I expect my data stream to undergo? Could it start receiving garbled data, or will it just cut off?
Is its functionality fully encapsulated by a byte stream? Suppose I want to relay 16-bit numbers. My first and only instinct is that I must come up with my own protocol (big-endian or little, for example) to pack my data into a byte stream and write to the port? It functions more or less like a network socket (minus the concept of packets) does it not?


texts: Unwanted Triggering in MOSFET driver circuit

texts:
I am trying to drive a resistive load with an N-channel MOSFET in linear region. This is the circuit I first simulated and then built on a prototype board. The signal is triggered by a 5V MCU signal, but for convenience I just replaced it with a pushbutton.

The problem I am facing is the unwanted triggering of mosfet. For example, I would get a DMM to check voltage across V1 and when I remove it the mosfet would get triggered. And it would not turn off for a while or until after I put the probes back across V1.

This description is strange but I'd appreciate if you could help me understand this random triggering. Is there something I am missing?
Is there a different approach possible for triggering the MOSFET in its linear region in this case?

Thank you!

simulate this circuit – Schematic created using CircuitLab


texts: Does the RMS value for a non-periodic signal exist?

texts:
Does the concept of RMS VALUE applicz to a non periodic continuous time signal?
If yes how to calculate it? If no, why is it not defined?

My doubt is : What value does an ac voltmeter display for an  input of non periodic square pulse of say 5V peak?


texts: Short circuit protection for an analog model train controller

texts:
I am developing a circuit for somebody else to control 3 analog DC model trains. I am unsure how I should make the short circuit part. There are more ways to achieve this.
My idea is as follows:

1 single 12V DC power supply is used to supply power to 3 analog controllers. One such a controller exists out of TIP120 Darlington transistor, a potentiometer, a DPTS switch (for direction) and a couple of flyback diodes.
The Tip120 in TO220 casings will be connected to a large metal plate and the trains are N-gauge so the current will most likely not exceed ~300mA.
The short circuit part (left side of the schematic) exists out of 3 Bc547 tranistors and a N-channel MOSFET which acts as the primary power switch (can be replaced by a relay as well).
The idea here is that under normal circumstances transistor Q1 is in conductive state. This causes Q2 to be off and Q3 (N-channel MOSFET) should also be high as the gate is pulled up to ~12V via R12.
All current of the tracks flows to shunt resistor R3. If the current exceeds 1.4A the voltage over this resistor will be 0.7V which should cause transistor Q4 to conduct. This action should cause Q1 to go out and Q2 to go on. If Q2 is on, it should pull the gate of Q3 to ~0V via R13 (100R). And this action should cut all power to the tracks. That is atleast what I want to happen.
It may be (though it is unlikely) that the starting current of a train's motor may exceed this 1.4A. In an attempt to prevent a shut-off I added C1 and R13 which should keep Q3 in a conductive state for about 0.1s. So for 0.1s I want to allow a short circuit. I believe that this should prevent the Tip120s from frying. This is the part of which I am least certain it would actually work.
After the power is cut off, one can reset the power by pressing SW1a. This should disable Q2 which enables Q1 and Q3 again.
I copied the idea from

ElecCircuit.com
The transistor Q4 was an idea of my own. I thought it would work better than the schottky diode in this example because it would also limit the maximum current.

I would like to use as few components as possible.
I would like not to use 'exotic' components which are hard to find.
I would like that the circuit does not die, not ever.
I would like to allow a short circuit for no longer than 100ms
All tip120 transistors as well the as the N MOSFET will be physically connected to a large sheet of metal for heat dissipation.

My questions:

Would this circuit work?
Is it a good idea to put the short circuit protection in front of the train controllers?
Is it likely that this circuit won't fry and die?


texts: Trying to understand PIC datasheet for the PIC 12F683

texts:
I'm new at asking questions on this forum so please forgive me if my format needs to be cleaned up. I have a PIC 12F683 datasheet. I'm trying to understand how, for instance, ANSEL=0 to set I/O to digital is obtained from a datasheet.

I have searched the web for some clues, but all I seem to find is "it just is." That's not helping me. I just need a little help getting past the bridge between the datasheet information and the actual code that manipulates these ports. Page 39 of "Programming PICs in Basic and page 32 (4-2) of the datasheet makes no sense to me... I'm not the first to post this sort of question from what I have found, but they didn't provide specifics. I'm hoping what I have provided will be enough for one of you folks to see what my question is and help.

I can see on page 31 (4.1 of the datasheet) that the TRISIO register determines direction and it seems clear that applying a "1" to that register will make the corresponding GPIO pin an input and so forth. But when it comes to the ANSEL=0 I'm lost- can't seem to make sense of this. Can someone please throw me a bone?


texts: Single Crystal Growing and Orientation (Silicon) using Czochralski Process

texts:
I'm working on small bibliographic research on photovoltaic panels, and I have chemistry background. I have confusion on crystallization (Czochralski method) imposed by the seed and following specific direction (111) or (100, etc.

1-Are all facets of the seed have the same lattice plane, meaning if you want (100) crystal a seed with all facets being (100) must be dipped into the melt?

2- What differences between directions in terms of crystal growing?

3- When crystallization is finished following (100) for example does the pure silicon maintain the original lattice structure of diamond?

4- In the Czochralski process, doping element is added to the melt. Why would the dopant sticks uniformly to the new structure or how to make sure it does that?

I appreciate practical details on direction of growing.

Thank you


texts: Does turning on inductive load (ex. AC motor) at peak input voltage reduce inrush current?

texts:
I was checking out the following project on hackster and at some point the author claims that

When the load is predominantly of inductive type, the turn-on is performed at the peak of the input voltage sine wave, in order to avoid core saturation [and] then reduce inrush current when driving e.g. large transformers.

Is this true? Why?


texts: Maximum Allowable Noise of ADC Input Signal

texts:
I have a question about calculating the maximum allowable noise for an ADC signal conditioning stage.

I have an existing signal conditioning stage as well as an ADC on a microcontroller.

I would like to use the existing stage and calculate the maximum allowable noise on the input signal in order to maintain an error of less than 1 LSB.

However, I am having a bit of trouble with the math.

The ADC has the following specs:

ENOB: 10 bits
SNR: 60 dB
Input Range: 0 - 5V
Max Sampling Rate: 1 Msps

The input signal has the following characteristics but the noise will vary depending on the sensor used:

BW: 150 Hz
FS Amplitude: 9V pk-pk

The existing signal conditioning stage has an attenuation of .5.

So far I have done the following math using this Analog Devices technical article:

Seven Steps to Successful Analog-to-Digital Signal Conversion

\begin{equation}
\text{ADC Input}_{RMS} = \frac{4.5}{2\sqrt{2}} = 883mV
\end{equation}
\begin{equation}
\text{ADC Noise}_{RMS} = \frac{883mv}{10^\frac{60}{10}} = 883 \mu V
\end{equation}

\begin{equation}
\text{ADC Noise Density} = \frac{883 \mu V}{\sqrt{\frac{1}{2}}f_{sample}} = \frac{883 \mu V}{\sqrt{500KHz}} = 1.24 \frac{\mu V}{\sqrt{Hz}}
\end{equation}

Now the signal conditioning stage has the following non-linear spectral noise density found using an LTSpice noise simulation:

Integrating this over the 150 Hz BW gives 926.67nV.

My question from here is how can I relate these two values and calculate the maximum allowable input noise?

Can I simply assume the input noise must be an order of magnitude higher than the root sum square (RSS) of these two noise densities? Am I missing something critical?

If there is any other information I can provide to help please let me know.


texts: How does a computer address ddr 4 sdram memory?

texts: I want to be able to manual address a 4gb ddr4 memory stick. looking at the datasheet for ddr 4 there are only address pins from A0 to A17 which is 18 bits, 2^18 = 262, 144 address spaces. So how does it address 4gb? It would need 32 bits right?


texts: "Switching Current" of switching regulator

texts:
I want to use a boost converter which will convert 3.6v@3.4A to 12v@1A i.e. 12Watts. I have collected different IC's datasheets by looking at the "Efficiency vs Output current" graph.

I am confused with "Switching current limit". e.g I am looking at the datasheet of LM2700 in which the "Efficiency VS Iout" graph shows approx ~85% @ 12|1amp (Vin 3.3v) which is acceptable for my application (screenshot is attached here).

But when I viewed the "Switch Current Limit VS VIN" curve; it shows that when Vout=12v, switching current is less than 2A (screen shot is attached here).

And my switching current is about >3.4A (i.e. >12W/3.6v). So this will not work for me? But how did they provide the "Efficiency VS Iout" curve at 12v@1A (Vin=3.3v) in the first place when this regulator isn't able to handle that much "switching current"? Maybe I am missing something.

I would be glad if someone can clear this point to me. Thank you.


texts: Designing a transistor switching circuit with opto-isolation

texts:
I am working on a project where I want to switch a 12V DC LED strip(power consumption 300mA) using ESP32 having a complete isolation between LED strip power source. I came up with following circuit.

Here optocoupler is PC817,
transistor is NPN 2n2222,
LED-STRIP_ESP_14 is the esp32 GPIO pin,
GND2 is esp32's GND,
GND1 is common for 5V1 and 12V+,
I'm using 5V at the phototransistor side of the pc817 because I have 5V readly available on another part of same circuit.
So, when LED-STRIP_ESP_14 goes HIGH, I want LED_STRIP to glow mode and when LED-STRIP_ESP_14 goes LOW, I want LED_STRIP to off.
Is this circuit designed correctly for the purpose?