texts: Transfer characteristics of circuits involving op amp with diodes


texts: Expressions in Verilog module instantiations

texts:
If I have the following verilog module definition:

module foo (
  input a,
  output b
  );

  assign b = !a;

endmodule

And then I instantiate it within another module like so

module bar (
  input c,
  output d
  );

  foo foo0 (
    .a(c),
    .b(!d) //note the not operator
  );

endmodule

I looked at the EBNF syntax definition for Verilog and it showed expressions as valid arguments for port assignment.
Will this do what I want (i.e. act as a passthrough—outputting c)? Or does verilog not allow operators other than concatenation for port assignment?

I realize this example is contrived, but my project has a decent amount of code so I didn't want to upload/explain all of it unless necessary.


texts: Is this CMOS circuit supposed to be an OR or an XOR?

texts: Since it has three NANDs and two NORs I guess it is an XOR, but doing the truth table I'm getting an OR expression. What's going on?


texts: Please help me to identify this connectors. They seems look like banana connector, but they are smaller (2 mm inside).


texts: Shunt resistor requirements.for 4-20mA current loops

texts:
1 ohm to 100 kilo ohms are called medium resistance and once I read somewhere that the shunt method is recommended in this interval but I don't remember where. I want to document a shunt resistor method used with 500ohm and I want to find a standard such as IEC, ISO ect. to verify what we do obeys to a standard.

How can I find it?


texts:
I am fairly new to FPGA design and I am working on a project where the FPGA is the SPI Slave.
Are there supposed to be constraints on the Master Clock input signal/ MOSI / Chip select?
What is the importance/reason for constraining inputs?
If so, how are these determined? If you have any suggestions for books or videos which give a deeper explanation I would greatly appreciate it. I just want to learn this so I can implement this module correctly.
Thank you


texts: How to measure phase accurately using LTSpice?

texts:
I am trying, and failing, to measure phase in LTSpice.  I've used the suggestion here
.tran 0.00001 0.5
.meas TRAN time_1 TRIG V(N001)=0 RISE=1 TD=0.4 TARG V(N001)=0 RISE=2 TD=0.4
.meas TRAN time_2 TRIG V(N001)=0 RISE=1 TD=0.4 TARG V(N002)=0 RISE=1 TD=0.4
.meas phase param 360*time_2/time_1

but the result isn't very accurate, even for the simple RC filter in the picture below.

How should I be doing it?
Note that the actual phase I need to measure is in a slightly more complex circuit, but I've reduced it to a simple circuit that seems to have the same problem.


texts: What does "Transient Response Recovery" means in the output specification of a AC-DC power supply?

texts:
I'm using a AC-DC power supply to provide 24VDC input to a PCB. A 100uF,35V tantalum is used as one of the filter capacitors for the 24V(same from supply) input of  DC-DC regulator on PCB. In some cases, this 35V tantalum capacitor goes bad and gets shorted and damages the PCB. I'm trying to find the root cause for this.

When looked at the datasheet of AC-DC power supply, one of the output parameter is as below

"Transient Response Recovery -<6% or 300mV of set voltage for 50% load change (above 25% load),500μs for recovery to 1% or 100mV of set voltage"

What does this specification mean?

Can the 24VDC output from power supply damage the 35V rated tantalum capacitor?


texts: Can I use the analog pins on the Arduino for my project as digital?

texts:
I am new to using Arduino, and I have an Arduino Uno. For the projects I've done, I've only used the digital pins.

I am building a small vehicle that uses stepper motors. I have run out of pins to control the motors for this vehicle. What are the analog pins for? Is it possible for me to use analog pins to control the rest of the step motors which I connect to the Arduino, or do I have to buy a bigger Arduino than Arduino Uno to control this contraption?


texts: How to separate the schematic of a RGB LED into 3 individual LEDs in Altium?

texts:
I'm designing a RGB LED matrix with the following footprint:

Which has the following schematic:

It's just a combination of three LEDs in one component. In my matrix design, I need to wire the individual LEDs to avoid ghosting. Thus the LEDs on the same component may not appear together on the schematic, like this:

As we can see the LEDs contained in colored dotted boxes are not put together.

To keep the matrix wiring clean and nice, I'm searching a way to breakup the component's schematic into three individual LEDs to be able to move around, but still having one footprint on the PCB.

Is there such a way to do it in Altium Designer? Or I'm going on a wrong path, and there's a better design pattern in this case?


texts: A full wave rectifier with resistive load is a linear load or non-linear load?

texts: we know if the applied voltage across a load is sinusoidal and also the current drawn is also sinusoidal then we can say that the load is linear load.But we also know that diode is a non-linear device. in case of full wave rectifier with pure resistive load the both applied voltage and current waveforms are sinusoidal, then can we say that the full wave rectifier with resistive load is a linear load?


texts: Superposition and average power dissipation

texts: Unfortunately, I am having trouble getting started on the question above. How can one model the affect of a voltage source on a circuit without the knowledge of the resistor configuration inside the circuit?


texts:
I think the question is not particularly MCU/board specified but I will be trying it on STM32F4-DISC board.

I was thinking of how to output a nice sinewave from a normal GPIO output pin, but I was not able to find a proper methodology. I am asking for a method of thinking, a guide rather than the complete solution.

Just give me an overview of the process.

If possible of course.

Thanks in advance.


texts: When measuring AC via an ADC, is it bad to have common ground?

texts:
I've got a circuit that looks like this:

circuit http://img.skitch.com/20111127-m6jqyx9b15brese4rkipayyib6.png

My input is low voltage AC at low current and I want to measure this with an ADC at 3.3V (eventually, haven't got there yet).

Is this safe/correct?  It appears to do what I want when I measure it with my oscilloscope, but it feels strange to me to be sharing an AC line with my DC circuitry (both connect to the same 0V).

I'm having trouble preventing the signal from dropping below 0V.  The closest I've got was to connect a schottky with the cathode to signal and the anode to ground.  I'm still seeing 300-400mV below zero on the signal line at particular instants.  I'm wondering if these things are related.

Edit:  Expanding a bit with more data (and updated the circuit to show opamp power).

While most measurements seem to be doing the right thing, the bigger the burst, the more likely it seems that I'd damage the device offering the reference power (in the deployment, it will be an atmega running at 3.3V).  I see drops down around -80mV or so, but when I had this hooked up to my washing machine, this happened:

It leveled out pretty quickly, but my understanding of operational amplifiers is only slightly greater than my understanding of Aramaic.  I've heard when you use them right, stuff like this doesn't happen.  I do believe that -2.4VDC would be a Bad Thing to hand off to an ADC.

Is this the wrong way to do things?


texts: I own one of those little pinhole 'spy cameras' that connect to your tv.and are powered by 5v? With an arduino and ethernet shield, would there be a way for me to create an IP camera type thing?


texts: Do I need to pay royalties to the SD card people if my device "just happens" to be compatible with SD cards?

texts: I'm designing something which will use an SD card. The device will be able to read and write the cards, using publicly available specifications. Do I need to pay the SD card people?


texts: Cheap surveillance camera solution with Raspberry Pi 3b+

texts: I have a raspberry Pi 3b+ and I would like to attach a camera to it to create something like a CCTV for surveillance. I want to use 13MP f/2.2 aperture camera from a broken smartphone with Sony IMX135 CMOS sensor. Is this possible with raspberry Pi camera board? Can I just replace the raspberry Pi camera with my smartphone camera just like that? So far I have tried to find some ready made boards online but I do not know if the raspberry Pi board will do the job because my camera is 13MP whereas the camera with raspberry Pi camera board is usually 5MP. I am really confused.


texts:
I need to trigger a camera using a 3.3V signal, the camera is at the end of a 3 meter cable. This camera has two trigger inputs, a 3.3V GPIO input and an optocoupler input with max input of 30V. I guess that the 3.3V signal will not work with a 3 meter cable so I should use a higher voltage. I happen to have a 24V power supply available. So I guess it will be better to trig the camera using a 24V signal. If I'm right, how can I easily convert the 3.3V signal into 24V? The trig frequency is just a couple per second so I don't think I need a especially fast circuit.

EDIT: maybe it would be better to lower the 24V to something lower like 12V or 6V, right?

The circuit on the camera side is:


texts: Finding the heat dissipation but calculations not going right?

texts:
I am trying to find the heat dissipation from a 20000 V 1 A filament which is on for 1 second. I just randomly came up with this to try to test my understanding of joules first law and ohms law with this problem.

Now when I start doing the math. The way I learned it was to first take volts and resistance to use find the power. So to find resistance I took \$1 A / 20000 V = 0.00005\Omega\$. Don't think I did it right though. But moving on.

Then to find power I did \$(1 A)^2 \cdot 0.00005\Omega =0.00005W\$ which I know is wrong. So I know I can't find. Joule heating or \$Q=I^2RT\$. Can someone help me out and break down how and when wrong. I'm just learning this and I'm very bad at math.


texts: The zero-input and zero-state response of a circuit consisting only of a dc source and a capacitor?

texts: From my understanding, the zero-input and zero-state responses of an RC circuit can be found by solving for the homogenous and particular solution of the ordinary differential equation found using Kirchhoff's current law. But I am confused as to what happens if there is no resistor in the circuit. In this situation, y(t) = x(t), where x(t) is the voltage input and y(t) is the voltage output across the capacitor. Now, my intuitive understanding tells me that the zero-input response is zero because no current has been provided yet and the capacitor is uncharged. But what about the zero-state response? Since there is no resistor in the circuit, will the capacitor simply not discharge? So, will the zero-state response of the circuit also be zero?


texts: Using a single voltage reference IC for several ICs?

texts: I have a circuit that has both a DAC and ADC that require a 2.5V reference. I could not find information regarding the operation of both devices from the single output of the Vref IC. Can this hurt the performance of either the ADC or DAC?


texts: Motion sensor to detect birds and small animals but ignore humans

texts:
I would like to develop a motion activated sprinkler to deter birds (cranes and other smaller birds) and small animals from eating the fish in my pond. I am using the approach of controlling a solenoid valve via a PIR motion sensor. However, this means the thing will activate even if humans walk past it.
Is there any method to trigger it only for motion by small animals (say less than 2.5 ft height)? I'm open to suggestions on entirely different sensors/methods.
Based on some pet friendly intrusion alarm websites, it looks like there may be PIR sensors that can be tuned to differentiate between animals less than 50 pounds vs more. I just can't seem to find the existence of such sensors.


texts: Order of electrical parts relative to interconnections

texts:
Are the following circuit parts (self made, not useful, and assuming there is more on each open side, just to make it a simple question) equal? I mean, does it matter if all connected items change order?

I heard that for correction capacitors the location should be close to GND and VCC of the IC to protect, but does this count also for the resistors/diodes in my example or for other parts or is it depending on the circuit of part (and where can I read about that)?

simulate this circuit – Schematic created using CircuitLab

The reason I ask is that for the following circuit, would it matter e.g. to put (on the right) the 470R right of the interconnection towards 74LS14 pin 1?


texts: Derivation of magnetising force on the axis of a short solenoid

texts:
Reference I will refer to is Textbook of Electrical Technology by Theraja, page 268
(iv) Magnetising Force on the Axis of a Short Solenoid
The derivation is already there. I just don't understand the visuals that well because they look so complicated. I don't get the use of the variables clearly such as the θ, dx, θ1, θ2, r, and l and even the points M, N and P. Recently I have already studied and understood (iii) Magnetising Force on the Axis of a Circular Coil. But what I don't get is why they have to use that on this part even though this is about a short solenoid. It's not even circular. I am already lost with the whole, use the circular coil thing. I understand the idea of using differentials to represent infinitesimal values but the situation this time feels so complicated.
I mean, the derivation is already there and pretty clear for someone else who probably understands the topic. I just want a more clear explanation, especially on the visuals and how it relates to the Circular Coil geometry.


texts:
I have used integrators in the feedback loop of standard inverting and noninverting amplifiers to eliminate DC off-set at the output, the circuit Im talking about is something like this

simulate this circuit – Schematic created using CircuitLab

I understand the function of the integrator, it samples the DC offset at the output and it starts ramping, the output of the integrator is feedback to the inverting input which gets added to the original offset but with opposite polarity, the integrator stops ramping (and stays there) when the offset at the output is zero.

Thats if we focus on DC, but what happens to AC?, imagine a 1KHz sine is inserted at the input, that means that the output of the integrator will be a cosine which is being fed back to the inverting input and added with the original signal. My question is: isnt this detrimental? I mean adding a cosine signal will affect the original AC signal (by a small amount), am I missing something?


texts: How is this MOSFET in a LTC3862-2 datasheet example only 60V?

texts:
SOLVED I was somehow looking at the wrong part (SI7370DP, not SI7430DP). This is sort of a useless question now.

I'm looking at the LTC3862-2 current mode step-up DC/DC controller for a 100V 1A supply solution, and I don't understand the MOSFET selection.

In this example circuit, Q1 and Q2 are Si7430DPs, which are 60V rated D-S. How is that right? I'm simulating this in LTspice, and I'm getting >107V across these FETs. Is this a mistake?

Would something like the IPB108N15N3 be a reasonable replacement?

If this was an oversight... I'm a bit nervous using this design. Does it otherwise look okay? Is there anything else here to be concerned with?

Would there be better parts to use for maximum efficiency and reliability?

SOLVED I was somehow looking at the wrong part (SI7370DP, not SI7430DP). This is sort of a useless question now.


texts: Why do rechargeable batteries have no short-curcuit protection?

texts:
Whenever I read a user manual to a device that runs off a rechargeable battery - like a cell phone or a power driver - the manual will always say I should store and handle the battery in such way that its terminals are not shorted by any objects like a paper clip or a screwdriver or any other stuff I might have in my pocket or bag. The warning further says shorting may lead to a battery exploding.

Why won't batteries have circuitry that addresses shorting and makes it less dangerous?


texts: Off the shelf SMD Ferrite coils are widely available and popular .The power ratings are adequate for many applications.The manufacturers are clear about the current ratings for saturation and copper heating .What the manufacturers often dont state is the repeatitive peak voltage rating.This is a potential trap because you could design a boost convertor producing hundreds of volts that works fine on the simulator and subsequently works fine on the bench.However it could fail down the track due to coil breakdown .This fail could be between turns or from terminal A to core to terminal B .Using a larger SMD coil than what is needed from a current ,Inductance standpoint should help.How much would overframing the coil help?  Is there a curve for peak volts Vs time?Sharply rising voltages which commonly occur in SMPS would probably make breakdown more likely .Is there an equation that relates rate of rise of voltage to breakdown volts? What is the temperature dependance of this possible breakdown ? Could a coil thermaly runaway and expire ingloriously?


texts: What causes the series resistance in capacitors?

texts:
Especially in high frequency circuits there often seems to be the problem of ESR of capacitors. ESR apparently is a characteristic of non-ideal capacitors, and is essentially a resistance appearing in series with the capacitance of the component.

But after doing some Google searching I haven't been able to find much info on what actually causes ESR. I understand that caps have wires, which always have some resistance, but if wires are the cause of ESR, wouldn't all other wirings of the circuit usually cause much more resistance to be considered? Since caps are basically just plates with a dielectric in between, the only other source of resistance I can think of is the dielectric. But let's consider electrolytic capacitors for example: The dielectric is an electrolytic liquid, shouldn't the liquid conduct electricity quite well? Why would there be much resistance? Or if we consider ceramic caps: What causes resistance here?

I understand ESR much better in the context of inductors, which often have many loops of thin wire, which can be expected to introduce lots of resistance. But what really causes ESR in capacitors?


texts: Beginner information related to constant current dummy loads

texts: I am beginning an electronics design project to build a constant current load to drive testings for batteries, bench power supplies etc. I have been hard trying to locate some black-on-white information over the Net to get the basics: what is the main operation principles of PWM controlled constant current dummy loads and, what do the particular parts like operational amplifiers of the circuit do. I think, I have been trying to find these basics with wrong search string but can't help myself anymore to invent some other words than "dummy load basics" or so. I hope you guys are able to help me in finding the answers.


texts: Why polarize a differential pair with a diode-connected BJT?

texts:
I was having a look at the LM148-family design

At the input stage, why would you polarize a differential pair with a diode-connected BJT? If I'm not mistaken, the output resistance is also going to be small. Perhaps to have a rather fixed collector potential?


texts: Calculating resistors to go with a thermistor

texts:
This battery regulator chip I'm using has a pin for a 10kΩ NTC thermistor to let it adjust the charge rate in response to the battery's temperature. You're supposed to choose two resistors to set the range of temperatures that the battery will be charged at. If the battery temp gets outside this range, charging stops.

The equations to choose the resistors are:

24kΩ = RT1 + (RT2 * Rcold) / (RT2 + Rcold)
5kΩ = RT1 + (RT2 * Rhot) / (RT2 + Rhot)

After a moment of juggling, I get this equation to solve for R2:
((RT2 * Rcold)/(RT2 + Rcold)) = ((RT2 * Rhot)/(RT2 + Rhot))+19000

Plugging that into Wolfram Alpha, I get solutions, but the values are negative!

Datasheet for the power regulator - The thermistor math is the last note on page 28.

Thermistor datasheets: Option A, Option B

(These are the two options for thermistors from the Seeed Open Parts Library. I was hoping to stick to one of these two, even if neither was the recommended 10k.)

Thoughts?


texts: Calculating collector current of NPN BJT with LED & resistor

texts:
I've been trying to wrap my head around the current I measured through the collector branch vs. the expected calculation for collector current and believe I have a knowledge gap in what to do.

The setup of the circuit is shown above with the LED being a blue LED with a forward voltage given as 0.3 V which seems implausible to me.

To find the collector current \$i_C\$ I measured the voltage drop  across the 330 ohm resistor as 1.9855V and calculated \$i_C=\frac{V_{RL}}{R_{L}}=1.9855/327\approx6mA\$.

From my prior calculations, I chose a base resistor that would give 20mA for my collector current with \$\beta=100\$ as a rough estimate as our beta is unknown but in the range of 100-300.

I'm not sure if my formula for collector current is incorrect as I'm expecting there to be quite a bit more current.
I tried another method which I'm not sure is right where I did

\$i_C=\frac{V_s-V_f{_{LED}}-V_{C}}{327}=\frac{5-0.3-0.00985}{327}\approx14mA\$
Which was quite a bit higher than from my other calculation, however when I put the forward voltage of the LED at 3V and put it back into the equation, I get about 6mA. So I'm not quite sure if the forward voltage of the diode given is incorrect as 0.3 forward voltage seems extremely low for an LED or if my calculations are wrong.

I haven't learnt much about diodes or transistors besides a basic overview before this experiment so I'm quite confused on where to go from here.


texts: GerbV (Gerber Viewer): How to do PNG export of only area within board outline?

texts:
Gerbv (open-source Gerber viewer) has the neat ability to export a customizable rendition of a given layer-stackup, to an output PNG.

Here is the manual (Ctrl+F for "export"): http://manpages.ubuntu.com/manpages/trusty/man1/gerbv.1.html

But no matter what I try, I'm unable to come up with any way to do that export such that only the area within the board outline, is exported to the PNG.

Currently the exported PNG will show a full rectangular area (along with a
set border area outside the board outline) even if the board outline is,
say, a circular one.

So, is there any suggested workaround to achieve the image of just the
exact board shape itself?

Or, alternatively, is there a way to assign a specific different color ONLY
to the "external background" area (i.e., the excess area around the actual
board outline itself) such that it is different from all colors of the area
inside the board outline?

NOTE 1:

For clarification, assume I'm starting with all standard Gerber layers including an outline layer.

NOTE 2:

Here are a few things I have tried so far:

1) Standard export:
GUI approach: Load all layers. File > Export >
Commandline approach: gerbv --dpi=600 --border=0 --export=png --output=fullBoard.png --project= myProject.gvp

2) Set window size for the export:
--window = <300,300>
This is only altering the rectangular window size (obviously it has no dependence on the actual outline layer of the board).

3) Image processing using GIMP (subtracting a representative color from the board background, i.e., the area outside the outline, and then performing a crop). Still trying, but so far, I am unable to come up with any universally working criteria for programmatically identifying JUST the area outside the board outline (represented by GKO).


texts:
Forgive me for the simplicity of this question but I am a microelectronics/very low voltage guy, and I have only 1 switch so I want to get it right the first time. Better safe than sorry :)

I have an ON/OFF switch. It is switches a 230VAC line from a wall outlet  on or off.

It has a LED to show it is ON, but I am not sure how to connect this. Now the Live line from the power connector is connected to B and via A to the circuit. If i want to use the LED, dow i have to connect C to neutral? I measured the resistor, which is 2,6k Ohm.


texts: VHDL - How does a process run concurrent with other processes and components while it executes sequentially?

texts:
Just as the title says, how does this occur?  I'm trying to wrap my head around processes vs components and I don't understand how this mechanism works.  This may not be a proper question so please help me formulate it to be more specific, but I just really need to understand this concept to keep moving forward in my design.

For example:

count: process (x)
  variable cnt : integer := -1;
begin
  cnt:=cnt+1;

  if (cnt > '9') then
    cnt:=0;
    OVERFLOW <= '1';
  endif;
end process;

I understand that the if statement is dependent on the previous increment statement.  I also understand why order is important (logically it makes sense - I check condition after updating), but what doesn't make sense to me is without any kind of clocking or other sequential mechanism, how does OVERFLOW (which is a signal in this example, not shown) get it's value updated concurrently with all the other signals in the design when it depends on cnt being updated first?  Furthermore, any other signals which have implied processes associated with OVERFLOW are assigned concurrently, making them dependent on cnt by proxy as well.


texts:
I was hoping someone could tell me what type of connector this is.

This is in an arcade cabinet connecting the speaker wires to a Sega amp (part number sj25-0361-01).

The width from outside edge to outside edge of the housing for both pins is .29 inches.

Thanks in advance!


texts: LM317 running digital pulses. Results are Noisy

texts:
The set up of my experiment so far:

A. I use a simple LM317 linear voltage regulator to supply constant voltage of +5V to Vdd of my Laser driver circuit.

B. Also I use another LM317 linear voltage regulator to supply voltage Vlda ( Up-to 12 volts ). Just the same way I shown in the previous figure , the source is from a 12V lead acid battery with 7.2 AmpHour rating.

C: The circuit of the Laser Driver:

** Questions:**

A : I don't get a clear pulse waveform and it seems very noisy. This is not the case if I directly supply voltage from a battery without the LM317 in between.

B : What is the difference between AGND ( analog ground ) and just Ground ( please see the highlighted areas in Laser Driver circuit ). I have shorted them as of now.


texts:
As partly derived from the following question: How to solder under already soldered parts?: I have the same problem as described in the other question (unsoldered wiring through the pcb, now no possibility to solder the pins of the adapters on the upper side of the adapter). But unfortunately the solution described in the other question does not work, because I can not uplift the restricting parts on the adapter (see also pics). I already tried to solder several wires on the pcb vias and connect them to the adapter pins, but that works only on a small adapter. Is there another possibility?

Pictures:


texts:
I would like to create a simple frame synchronihed stereo camera. I found there are cheap OV7670 boards (without FIFO memory) that work with Arduino (or compatible) boards - these sensors do not have an oscillator on board and accept external clock signal. The basic idea is to feed both cameras with a common clock signal.

The cameras are controlled via I2C interfaces where the resolution, image format etc. are being set. I think there may also be a need to configure both sensors at exactly the same time since the change of resolution/framerate will most likely affect the synchronization. This may lead to the requirement of two separate I2C buses that are able to issue a command exactly at the same time.

Could someone prove my assumptions right or wrong please? And possibly direct me to hardware capable of doing the parallel I2C stuff I need? Thanks.


texts:
Why is the following function NOT invertible?

$$y[n] = \frac 1 {x[n-1]^2}$$

A function is invertible if two distinct inputs give two distinct outputs.
Is there a quick way to check for invertibility?


texts: I recently got into eletronics, and there are some concepts I am having a hard time understanding. I was looking around youtube and saw this video of a small EMP generator, I understand the basics of it, the magnetic field inducts a current thus frying electronics, but what I'm interested in is why there is a spark gap in the schematics. What does it do ?


texts: Can we use PWM on the cheap RX{n}[letter]-TX{n}[letter] Integrated Circuits

texts:
The market has been inundated with cheap RC toys. Most of them use the RX/TX Integrated Circuits that have 5 to 9 functions:

PT0090 Series Datasheet
RX2/TX2 Datasheet

All of them operate on an ON/OFF state.

Has anyone tried to feed a PWM signal to these and see if they have enough frequency output on the Receiving end?


texts: What kind of electronic component is that? A lightbulb?

texts:
Found this component in Canon printer power supply

It follows a protective varistor in series and is followed by a some kind of serivse terminal that had its own hole in the power supply's case, and is connected to nothing. The component is close to to the AC input on the board, and has AR1 printed next to it

It appears to have infinite resistance and no capacity. It has triangle-inside-circle-symbol:  folloed by 202 followed by T02E printed on it. Google search gave me nothing.


texts:
I am trying to do some surface mount soldering for my project and have hit a few snags.

My hot air gun works perfectly fine for most of the PCBs I am making but one type in particular is problematic. Due to the fine pitch of the chips I am using, and the number of very small components on the board I cannot seem to get a good board out of my current process as the components have a bad habit of shifting due to the air flow.

Due to the fact that the board is 35cm long it will not fit in any desktop ovens I have found and I just don't have the money nor the long term need to invest in any industrial equipment.

I've tried ordering two different induction hobs off of amazon in the hope that I can run them at somewhat accurate temperatures but I have hit the same problem in both cases. My tray started smoking and when I checked the temperature with a laser thermometer both heated up in excess of 440 C when I had them set around 160.

I think this may be due to the size of the tray I have to use, rather than a fault with the hobs themselves?

Anyone able to point me in the direction of an oven that is large enough for what I need but is under £250?
Or perhaps someone can recommend a hot plate that will do what I am expecting / an entirely different process?


texts: Are there platforms where disabling/restoring interrupts from ISR should be done differently than from non-ISR context?

texts:
I'm familiar with several real-time kernels: AVIX, FreeRTOS, TNKernel, and in all of them we have 2 versions of nearly all functions: one for calling from task, and second one for calling from ISR.

Of course it makes sense for functions that could switch context and/or sleep: obviously, ISR can't sleep, and context switch should be done in different manner. But there are several functions that do not switch context nor sleep: say, it may return system tick count, or set up software timer, etc.

Now, I'm implementing my own kernel: TNeoKernel, which has well-formed code and is carefully tested, and I'm considering to invent "universal" functions sometimes: the ones that can be called from either task or ISR context. But since all three aforementioned kernels use separate functions, I'm afraid I'm going to do something wrong.

Say, in task and ISR context, TNKernel uses different routines for disabling/restoring interrupts, but as far as I see, the only possible difference is that ISR functions may be "compiled out" as an optimization if the target platform doesn't support nested interrupts. But if target platform supports nested interrupts, then disabling/restoring interrupts looks absolutely the same for task and ISR context.

So, my question is: are there platforms on which disabling/restoring interrupts from ISR should be done differently than from non-ISR context?

If there are no such platforms, I'd prefer to go with "universal" functions. If you have any comments on this approach, they are highly appreciated.

UPD: I don't like to have two set of functions because they lead to notable code duplication and complication. Say, I need to provide a function that should start software timer. Here is what it looks like:

enum TN_RCode _tn_timer_start(struct TN_Timer *timer, TN_Timeout timeout)
{
   /* ... real job is done here ... */
}

/*
 * Function to be called from task
 */
enum TN_RCode tn_timer_start(struct TN_Timer *timer, TN_Timeout timeout)
{
   TN_INTSAVE_DATA;  //-- define the variable to store interrupt status,
                     //   it is used by TN_INT_DIS_SAVE()
                     //   and TN_INT_RESTORE()
   enum TN_RCode rc = TN_RC_OK;

   //-- check that function is called from right context
   if (!tn_is_task_context()){
      rc = TN_RC_WCONTEXT;
      goto out;
   }

   //-- disable interrupts
   TN_INT_DIS_SAVE();

   //-- perform real job, after all
   rc = _tn_timer_start(timer, timeout);

   //-- restore interrupts state
   TN_INT_RESTORE();

out:
   return rc;
}

/*
 * Function to be called from ISR
 */
enum TN_RCode tn_timer_istart(struct TN_Timer *timer, TN_Timeout timeout)
{
   TN_INTSAVE_DATA_INT;    //-- define the variable to store interrupt status,
                           //   it is used by TN_INT_DIS_SAVE()
                           //   and TN_INT_RESTORE()
   enum TN_RCode rc = TN_RC_OK;

   //-- check that function is called from right context
   if (!tn_is_isr_context()){
      rc = TN_RC_WCONTEXT;
      goto out;
   }

   //-- disable interrupts
   TN_INT_IDIS_SAVE();

   //-- perform real job, after all
   rc = _tn_timer_start(timer, timeout);

   //-- restore interrupts state
   TN_INT_IRESTORE();

out:
   return rc;
}

So, we need wrappers like the ones above for nearly all system function. This is a kind of inconvenience, for me as a kernel developer as well as for kernel users.

The only difference is that different macros are used: for task, these are TN_INTSAVE_DATA, TN_INT_DIS_SAVE(), TN_INT_RESTORE(); for interrupts these are TN_INTSAVE_DATA_INT, TN_INT_IDIS_SAVE(), TN_INT_IRESTORE().

For the platforms that support nested interrupts (ARM, PIC32), these macros are identical. For other platforms that don't support nested interrupts, TN_INTSAVE_DATA_INT, TN_INT_IDIS_SAVE() and TN_INT_IRESTORE() are expanded to nothing. So it is a bit of performance optimization, but the cost is too high in my opinion: it's harder to maintain, it's not so convenient to use, and the code size increases.


texts:
I'm looking at the design below. I am reading this webpage where the picture came from.

What I'm aiming at is the wisdom behind the design. Looking at the two transistors facing downward, I assume that the voltage at the collector region is amplified from the base since the emitters, given that A and B are receiving low input signal, are grounded.  That'd make the transistors facing each other to turn on, and have the output spot perform the NOR logic. Does that make sense?


texts: How to determine minimal detectable acceleration on accelerometer?

texts:
How can it be determined the minimal detectable acceleration on analog and digital accelerometers? In datasheets I found only specification like sensitivity, noise etc. And how the minimal time for detecting can be found?

As example, product site and its datasheet


texts: USB supply protection using shotkey diode

texts:
Here is the atached schematic of the clamping diode condition. Isolated the connection to contoller and kept the end open. When USB input is varied above 5V the expected output is diode cathode voltage (5V) + diode drop, which I was getting when im simulating the same.
Tried to test the same condition on board level buy varying the USB input above 5V ,I'm seeing the same USB input voltage at output (diode anode). Please let me know what is the problem in real case.


texts: Amplification before tubes and transistors were invented

texts:
Telephones are older than vacuum tubes and of course transistors. How was signal amplification done?

I mean the technology, not the details.

EDIT

Some additional informations that I should have given at the beginning :

The question is restricted to telephony
I'm not interested in experimental equipments Say for example that the equipment should have been done in quantity more than 30 pieces, or better that it has been a commercial product.
I'm not only interested in purely electric solutions : it can be mechanical, hydraulic ... (but without human repeaters !)
impedance adaptations (acoustic or electric ...) are not considered here as amplification.

SUMMARY OF THE ANSWERS

There wasn't any amplification between the microphone and the headphone, even for a 1200km transmission, but yelling was necessary at one side, and absolute silence at the other side (see WhatRoughBeast answer)
the carbon microphone itself is an amplifier. The general definition of an amplifier is not always very easy (see Ali Chen answer, and BillF second answer, if you can follow), but it suffices to say that an electrodynamic speaker coupled to a carbon microphone is an electrical amplifier (see next-hack answer and BillF first anwer). I add that the other kinds of microphones are attenuators (hence the question)
the best telephonic lines have a loss of only 0.04dB/km at audio frequency. (compare with 10dB/km at 300kHz for our telephonic lines)
The loudest sound that a human can stand is more than 80dB above the lowest he/she can ear. (RussellBorogove comment). It is possible that the sound inside the horn (see peufeu answer) is even louder than what a human can stand.

Thanks for the contributions.


texts: How can I estimate the minimum baudrate for a given bitrate?

texts:
My circuit performs data acquisition at 250 samples/s, 24 bits/sample and transmit this information to the local host (PC) through a bluetooth module that implements the UART protocol.

As far as I know, for each byte transmitted there is 1 start bit, 2 stop bits and 1 parity bit, resulting

(250 samples/s) * (24 bits/sample) / (8 bits/byte) * (12 bits/transmitted byte) = 9000 bits

in 1 second.

Supposing there is one bit per transmitted symbol, the minimum  baudrate that would work for this case is 9600 bauds. However, the tests we've performed so far are not convincing, since the received data is contaminated by some enormous jump discontinuities (about 10^13, see figure below).

Could you please tell me how I can estimate the minimum baudrate?
How would you estimate the baudrate when including the bluetooth module?


texts: choice of heat sink (thermal resistance)

texts:
I want to calculate the thermal resistance resistance for my board:
I found on the amplifier datasheet how I should calculate.

I found a value of -0.389 °C/W which seems wrong to me. I don't know if I took the right value to calculate the resistance.
to power the amplifier I used 3 power supplies (2 power supply (+ -100v) and 1 power supply (+ -15v)


texts:
There are measuring instruments that measure distance by measuring the time a lightbeam takes to come back. An example is a LICA scanner, that uses this tecnology to make 3D models of objects using laser beams.

Question is: How is it possible to measure how long light takes to get from point A to point B and back if light travels so fast? Isn't electronics too slow to measure such tiny time differences? What about the time electronic components need to change its state?


texts: CycloneIV PCIe hard IP fixedclk_serdes generation

texts:
I'm trying to build a minimal design with PCIe on CycloneIV, and have trouble getting the core_clk_out to actually run.

In the PCIe user guide, page 13-9, it says that fixedclk_serdes may not be derived from refclock for offset cancellation to work.

If I feed this from a free running 125 MHz clock, core_clk_out does not toggle, however if I connect the refclock to a PLL block, generate a 125 MHz clock there and connect that to fixedclk_serdes, core_clk_out toggles at 125 MHz.

If I look at a Qsys generated design for the same board, this appears to be indeed correct -- Qsys also generates a 125 MHz clock from the refclock using a PLL, and uses that for the SERDES.

Can anyone shed some light on this? Is the documentation incorrect, or am I missing something here?


texts:
Can anyone identify this tiny connector?  The tape measure is in inches.  The connector has threads on the outside and a pin inside.  The diameter is about 1/16th of an inch.  I think it might be an SMC connector but I am not an expert in this stuff.

This connector is on an accelerometer.  I will need to get a custom cable to connect to the accelerometer; the other end will be a BNC connector.  Does anyone know what type of cable I would want to use for this?  My lab mainly uses BNC cables, and they're all RG58, which is way too big for this tiny accelerometer.


texts: Questions about cascode current mirror with MOSFETs

texts:
I have some queries related to this circuit:

Is there any way where we can implement it with non-matched MOS transistors?
If not, how do you calculate the I_output and I_ref relationship?
I am implementing it but I am not sure how to choose the right values of resistances and source voltages.

This is the circuit:


texts: Is a microswitch ON when slightly pressed?

texts:
I'm working on an old Instax camera, it has a mechanism to release photos with a series of gears. When the shutter release is pressed, the gears turn and an arm pushes the exposed photograph out of the camera. When the arm returns back to its neutral position, the camera should stop the gears from turning.

This works via a microswitch pressing against one of the cogs - the cog has a gap in and when the arm returns to its neutral position, the micro switch should fall into the gap of the cog it's next to and stop the cycle/process.

The microswitch is touching the cog and does press it in slightly like it should when the switch is not in the gap of the cog, however the force of it being pressed in isn't enough. I've tested the microswitch, it's working but it's only activating when pressed in further, so it's almost like it isn't close enough to the cog. The result of this is that the system never thinks the arm has returned to the neutral position and keeps pushing photos out of the camera.

In this position, the microswitch should be ON (but isn't). You can see the gap in the cog here while the switch isn't sitting inside it

In this position, the microswitch should be OFF (it's sitting inside the gap shown in the first picture)

So my questions are - is a microswitch in the ON state when pressed in only slightly, and can a microswitch lose sensitivity over time?

A bit of background: The microswitch was working correctly before I took it apart to clean rollers inside of the camera. I was careful doing this, but after putting it back together, this process doesn't work correctly anymore sadly. I don't feel like there are any parts missing, so I'm very confused as to why the microswitch isn't working now. In an attempt to get it working, I've tried adjusting the copper microswitch part but this hasn't worked. Please excuse any bad use of technical terms if I've described anything incorrectly!


texts:
I designed the following zero crossing detector using an FOD819S optocoupler (U5):

The source of the optocoupler is connected to a MB6F full-bridge rectifier (D2) which is supplied by a 9V transformer connected to 220V AC/50Hz. The 3.3V regulator (U8) supplies power to an ESP32 microcontroller and a segment display (not shown in schematic).

I probed the circuit in T1 (in blue, relative to GND) and it works as expected most of the time. For reference, I connected another probe to T2 (in yellow) before the full-bridge rectifier.

However, when cutting and re-applying AC to the transformer, it sometimes shows some odd behavior:

Or it simply stays at 0V:

Another issue is that the detected frequency is ~10% above 100Hz (not stable) which is also what I detect from a microcontroller using an interrupt on falling edge. It might be a consequence of the slow rise time.

What is wrong with this circuit? Should I add a constant load before the regulator?

Solution

Here is the signal when using the first circuit from Dave Tweed (with a pull-down resistor):


texts: Level shift from 5V to 3.3V (and vice versa) using 74HC4050N,652

texts:
Below you will find a link to the datasheet for 74HC4050N.  My order I placed had a suffix of ",652" on that part, but I'm not sure what that number refers to.

http://www.nxp.com/documents/data_sheet/74HC4050_CNV.pdf

I'm trying to level shift a 5V data input to 3.3V output with this component.  Most level shifters that I've found in the past have two VCC pins.  One for each specific voltage.  This looks like the VCC pin will take -0.5V to +7V.  So I'm not sure what voltage I should connect.  The -0.5V confused me.

Also, the A pins and Y pins have a Low and a High, I think.  So I'm not sure how those should be used either, and what pins signifies an actual channel.

Here's ultimately what I'm after:

I have my Arduino with a TX pin and Rx pin.  Then I have a module needing 3.3V and has TX and RX pins as well.  However, I read that I need to level shift these two pins since the Arduino is 5V, and doesn't match the module (3.3V).

PS: I'm not an electrical engineer, so this may sound trivial.


texts: Device that uses a USB port for application downloads in an application/executive model -- what class should it be?

texts:
So, I'm building a device (it's a programmable, USB-powered RGB LED lamp, so it's rather silly :) but this problem comes up in more serious contexts as well, such as when a PLC provides a USB interface for application download to the PLC) that is going to use an application/executive model for the firmware -- the executive is programmed into Flash, implementing the USB device and core I/O functions as well as an interpreter for the application firmware, which is compiled to some sort of intermediate format before download to the device, which stores it in a separate memory space (an EEPROM or a separate Flash).

However, this raises the question of "what class should my device be?":

Vendor class is always an option, but it's something I'd rather not resort to unless I had to as it makes the tooling just that much more annoying without gaining me much over a "dumb pipe" solution, unless there are existing vendor class de-facto standard protocols I can follow for this?
You'd think DFU would make sense, but it's really designed for monolithic device firmware, not applications in an application/executive model
Mass Storage is not simple to implement (due to having to deal with command sets optimized for complex storage devices on the order of GB or TB, with way more going on inside them than a simple, randomly-accessible EEPROM or the likes)
CDC has a couple options -- CDC-ACM works everywhere, but requires a bit of extra gook to deal with the encapsulated-command business.  Linux also supports CDC without a control model through the "generic" usb-serial driver, but it's not clear if Windows can be cajoled into supporting such a "skeletal" CDC implementation without having to write code.  (I can sacrifice Windows support in this application, but it'd be a nice-to-have even if it's at a "should work" state.)
HID also provides a couple options: one can implement a "dumb pipe" over HID if CDC isn't an option for some reason, or it's possible to do more sophisticated protocols via HID as well.  This has the advantage that both Windows and Linux deal well with talking to HID devices from userland, but has downsides as well, since this isn't what HID was intended to do.
Media Transfer Protocol provides a Mass Storage alternative that works more along the lines of a filesystem (and is thus simpler in some ways) but has the downside that it is not supported very cleanly on Windows (Explorer handles it OK, but it is not handled cleanly from a scripting/command line standpoint at all).  Linux tends to be a bit picky about MTP devices as well...

Anyone out there know what's been done before in this type of application?


texts: Why are there no decent 9V block chargers?

texts:
Forgive my ignorance, I'm not an electrical engineer. Can someone explain why there apparently are no decent chargers for 9V blocks? There are two issues I would like to clarify:

Normally, you can not charge LiOn batteries on a NiMh charger and vice versa. Also, I have never seen a consumer grade charger that can handle both types. However, with 9V, some claim that they can charge both NiMh and LiOn. I suspect faulty product description, and find it dangerous, but what does an expert say? Is it even possible for the charger to detect the type of cell? Can a 9V LiOn block blow up in such a charger?
Why is it so difficult to charge 9V blocks with the same comfort as 1.2V cells? I have yet not seen a charger that displays the current charge status & progress bar and has a reliable charge stop. With 1.2V cells, almost any 30EUR charger can do all of these things. Are there technical issues at work, or is it just a matter of poor/cheap product design to increase profit? Because even the "high end" devices do not do a better job at this.

I'm talking about consumer grade devices in the price range below 50 EUR.


texts: Crockcroft-Walton Voltage Multiplier Large Voltage Loss

texts:
I have a CW voltage multiplier that uses 30kV, 1nF capacitors and doubled 20kV, 5mA, 100ns diodes (for a total of 40kV). My ac source is a sine wave (viewed on the primary side of the transformer because the secondary is beyond the capacity of my oscilloscope) around 20-24kHz and produces 15kV DC when half-wave rectified (measured after the 150Mohm resistor.)

simulate this circuit – Schematic created using CircuitLab

The output voltage of the CW multiplier is only 1.5kV. I have tested the diodes and capacitors. 100ns is compatible with most frequencies below 1MHz, I believe.

I am thinking that it might be perhaps that the 12  \$\Omega\$ resistor is not allowing enough current to charge the capacitors, but maybe it is some thing else such as some reactance I am not taking into account?


texts:
I have a battery, where the negative terminal is being switched by an NMOS circuit. I also have a solar charge controller, which is controlled by serial interface. The serial interface requires common ground. A microcontroller is connected directly to the battery.

Problem: Current flows to the battery via the serial interface ground loop (and causing lots of smoke, too).

simulate this circuit – Schematic created using CircuitLab

Question: How can I maintain the serial connection, without creating a ground loop? Can I make galvanic isolation with discrete components?


texts: How do I calculate maximum current that each pin of PC8575 is able to sink?

texts:
http://www.nxp.com/documents/data_sheet/PCF8575.pdf

Can somebody tell me which parameter one should look for while looking for calculating maximium Current source/sinked by a pin.


texts:
This is my circuit that was made on tinkercad. The issue is that 7408 is blowing up every time when 2 switches are on but three switches it works. I just needed advice on how to fix this. At the bottom of the page is where the truth table and diagram is.
Boolean equation is AB + AC + BC (AB is Orange, AC is green, BC is light blue)
Material: 74HC08, 74HC32, led, three switches, power supply and lastly 470 ohm resistor.

This is a picture of the circuit when it accepts 2 inputs only.


texts: 3 Phase line to line voltage application

texts:
I've been tasked with designing a three phase system to be sent over to the US and have encountered a few questions along the way.

My system will be hooked up to a 208Vac three phase socket and most devices that I am using in my system are happy to be powered by the line to neutral voltage that you get from 208V three phase of 120Vac. However there are two devices that require a minimum of 180Vac (I guess they are not intended to be used in the states).

I understand that the line to line voltage in 208V three phase is 208Vac which would be be fine for these devices of which I have two.

My question is, are there any adverse effects when you wire up a system this way or is this perfectly standard practice. I guess that you can probably tell that my experience in this field is fairly limited.

Any help would be greatly appreciated thanks.

I have attached a picture of what I intend to do for clarity.


texts:
What is the role of the outer metal connector? (the one with two square holes)
Does it have a potential? Is it insulated from the 4 pins? Are the 4 pins insulated from each other?


texts:
I am trying to build a 16 bit single board computer based around the 68000 and am wondering if there are any non proprietary 16 bit graphics chips like the Yamaha V9958 with readily available datasheets.

Thanks


texts:
I am new to both arduino and electronics. Where would I start making a wireless Aduino USB cable. Which readings or websites can I go to for more information? PLease help...:)

This cable should be able to accept USB signals, translate them to be sent over WiFi, and then translate them back to USB on the other side. This should be done by Arduino.


texts:
I have a LED matrix and I want to light up the LEDs at (C1, R1) and (C4, R4). So I connected R1 and R4 to 5V and connected C1 and C4 to ground.

But the problem is that (C1, R4) also lights up. Is there any way to avoid this?

I have limited number of 5V and ground ports so I can't connect each LED to it's own 5V and ground port. It is also required that (C1, R1) and (C4, R4) are continuously lighted up. So I cannot remove the voltage supply at any instance.


texts: Suggestion to electrically disable a Faraday Cage

texts:
My plan is to ultimately develop an Autonomous Faraday Cage. The project seems very straight forward; however, I am unsure on how to effectively control the cage (turn on and off).

I have constructed a prototype Faraday Cage at home. From my research on these cages, my first theory was that an un-grounded cage with no external charge should not block the electromagnetic waves emitting from a cell phone. However, placing the phone in the cage, I observed that the cell phone still lost its network capabilities.

Google has provided no suggestions on how to disable the qualities of a Faraday Cage electrically. Obviously, I could arrange a method where the cage opens, allowing the phone to reconnect to the network and Bluetooth. I don't see this as ideal however since my design would involve moving parts (a final design I plan on completing thousands of iterations).

Are there suggestions on how to electrically disable the Faraday Cage?

Extra Note: As I wrote this, I just thought about grounding the inside and outside of the Cage. From my understanding, a Faraday Cage works by creating its own electromagnetic field which cancels external and internal Electromagnetic waves.
My reasoning on grounding the inside and outside is that if there is no charge to create the electromagnetic field, then the electromagnetic waves could escape the cage. Is this a reasonable theory?

TL;DR: How may I electrically disable a Faraday Cage?


texts:
I have a PCB with no solder mask with a very dense layout and a very fine trace spacing.

I didn't get a solder mask because it's still in the prototyping phase, and it's way cheaper.

I keep having to stop, find the new shorts that keep popping up, and remove metal fibers that are barely visible.

From what I can tell the fibers are aluminum from the pcb so a magnet is no help.

Is there a trick to remove them faster or a way to stop this from happening?


texts: OTA design, the Gm won't go down to zero

texts:
I'm trying to simulate a pseudo-differential OTA, but the the Gm vs Vin(differential) plot I obtain seems warped. The Gm won't go down to zero for large values of Vin.

attached is the circuit schematic, and the waveform. The top waveform is the Gm vs Vin(differential) plot and bottom is the current.

this is done in 65nm CMOS.

the Gm plot should be symmetrical on both sides, and so what could be causing this?


texts: Distortion is introduced when speaker is connected to the output of the amplifier

texts:
I have a circuit that implements a guitar amplifier (I ordered a couple LM386 but in the meantime I used an OP484). The following figure represents my schematic: (cap C2=10uF as well)

The signal from the guitar seems to amplify perfectly and without much noise when the speaker is not connected:

but as soon as I connect the speaker to the output of the amplifier the amplified voltage goes way down and the signal gets very distorted which sounds like a lot of humming noise, the clipped signal can be observed in the following image:

Any ideas why this might be happening? The only thing I can think of is maybe an impedance mismatch and if that is the case, how would I solve it?
(the speaker data sheet says impedance is 8 Ohms)


texts:
Sending and Receiving Data
//Function to send and receive data for both master and slave

unsigned char spi_tranceiver (unsigned char data)

    {
        // Load data into the buffer
        SPDR = data;

        //Wait until transmission complete
        while(!(SPSR & (1<<SPIF) ));

        // Return received data
        return(SPDR);
    }

What part of it sets the pin (MOSI) high and low to transfer bit. All i see is the awaiting for the interrupt bit (SPIF).

Does AVR MCU automatically handles all routine regarding pusling pins just by setting SPE bit to 1 ?

"To send data, load the data into the SPI Data Register (SPDR), and then, wait until the SPIF flag is set. When the SPIF flag is set, the data to be transmitted is already transmitted and is replaced by the received data. So, simply return the value of the SPI Data Register (SPDR) to receive data."

Another line from the same post - i do not expect that mcu will start transmitting as soon as i put data in data register


texts: Photodiode transimpedance amplifier with integrated filtering

texts:
In a previous question about transimpedance amplifier stability, one interesting suggestion was that instead of trying to do multiple stages of op-amps in order to provide equalization for my signal, I should consider trying to integrate the filtering into the transimpedance stage itself rather than as a second, following stage.

Here is one possible way to do that:

simulate this circuit – Schematic created using CircuitLab

Essentially, it is a normal transimpedance amplifier with feedback capacitance preceded by a current divider.  At high frequency, the inductor L1 is an open circuit, and the TIA works like a normal TIA receiving most of the photocurrent.  At lower frequencies, the inductor passes current, attenuating the signal.  By tuning the values of L1 and R6, I could move the corner frequency around and equalize the photodiode impulse response.  I have a couple of questions:

This seems like a fairly simple idea, and intuitively I would expect the inductor to have no affect on stability (or the value of C1) because its impedance will be high at frequencies where the phase margin decreases but I couldn't find much about doing this on Google, which makes me worried that I have missed some obvious reason this won't work.
If I use a bipolar opamp, am I likely to have trouble with the relatively small value of R4 needed to balance the input voltages caused by the offset current?
The series resistor R5 will introduce a voltage drop when current flows, resulting in the photodiode seeing a smaller reverse bias.  Presumably this will introduce distortion at high current, but is there some way I can estimate how much current is tolerable (or equivalently how small I need to keep R5 to maintain reasonable linearity)?


texts:
simulate this circuit – Schematic created using CircuitLab

I am studying for an exam, and was given this problem to practice. I have finished a good portion of it, but run into some issues that make me question if I've made a mistake.

Question:
Find the Q-Point of the circuit (above).
$$K_n = 1 {mA}/{V^2} $$  $$V_{tn} = 2 V$$

My Work:

$$Q-Point = (I_{D}, V_{DS}, V_{GS})$$

$$ I_{D} = K_n(V_{GS} - V_{TN})^2$$
$$V_{GS} = V_g - I_dR_s$$
$$V_g = V_{DD}*(R_2)/(R_1+R_2) = 20/4 = 5 V$$
$$V_{GS} = 5-2700I_D$$
$$I_{D} = .001(5-2700I_D - 2)^2$$
$$I_{D} = .001(7290000I_D^2 - 16200I_D + 9)$$
After troubling with the algebra...

Id = 1.57 mA or .783 mA

Thus:

Vgs = .761 V or 2.9 V

This is where I'm confused - why do I have two answers for Id and Vgs?


texts: Why doesn't this Colpitts oscillator work?

texts:
I am learning about LC circuits.  I tried to build one by myself.  The schematic is in the picture below.

When I turn on the power, I can't get any AC output from R1 on multimeter, but I can get some DC voltage.

Because the frequency in this circuit should be around 10kHz, I connected R1 to a power amplifier, and I can't hear any sound.

Does anyone know why it is not working or if it is working and just I used the wrong way to measure it?


texts: What FPGAs support USB 3.0 super speed OOB signals?

texts:
I would like to build a USB 3.0 PHY with FPGA. I have heard that some FPGAs transcievers should support OOB that is used in USB SuperSpeed differential lines. I am also wondering if such devices exist in ball-less package (I would like my device to use 2 layer PCB).

I am aware of FX3 devices from Cypress and PHY from Texas Instruments but they are both BGA devices.


texts: How to measure the car battery charge with good precision

texts:
My goal is to replace the analog battery gauge in the dashboard - with a more accurate, digital gauge.

My first idea was to look for a specialized IC. I'm familiar with battery gauges for LiPo batteries like the STC3100IST, so I thought "probably there's something similar for lead-acid batteries, since they are used in nobreaks".

And indeed there was, like the bq78412 - but all hard to find, overwhelmingly complex. Also, they are designed to measure multiple cells, with current measuring features which for a car are of course not useful (think about installing a current sensing resistor...)

Then, my second choice was just to use an ADC after a voltage divider made with resistors to reduce from the 12-14V to hundreds of milivolts - giving a 10x margin to survive voltage spikes.

But this second choice seems almost too simplistic. Will it work? Will it survive the harsh environment a car is? Are there any feasible alternatives?

Thanks in advance.


texts: Electrical specification for minimum bias current available from 3.5mm cellphone microphone input?

texts:
If I understand correctly modern microphones integrated with headphones with 4-contact 3.5mm jacks for use with cell phones are condenser microphones, and usually contain a small, integrated amplifier - consisting of at least one FET and a few passives for bias isolation.
These are very low current, but require a small DC bias available from the microphone input to operate, and usually a resistor divider there requires and draws at least a small current.
Question: Is there a standard, or generally and widely accepted minimum current that a designer can expect any modern phone to make available at the 3.5mm 4-contact plug - or voltage plus maximum internal series resistance (within the phone)? I'm guessing it's going to be somewhere in the ballpark of 1 to 100 micro-amperes and between 1 and 2 volts, but I don't actually know this for sure.
Here is just a random example, the TPA6166A2 3.5-mm Jack Detect and Headset Interface IC was the first I found in a search, and it seems to be rated to supply a maximum of 1.2 mA when it detects a need for it and the internal bias resister is set to bypass. However it is no evidence by itself of a minimum standard.

There are plenty of examples, and other questions within this stackexchange, but so far I haven't found the actual published, or industry accepted minimum current, or minimum voltage plus maximum internal(phone) series resistance.
Hypothetical use example: This is not what I'm doing but it's a good working example for the question. "pico-LEDs" - small surface mount LEDs attain useable brightness at only a few milliamperes. A power harvesting-like circuit could collect enough charge from say 50 microamperes over one minute to "blink" the LED for 100 milliseconds.

above: screenshot from an example picoLED-eco surface mount LED.
Comments on personal experience are welcome, but for an answer I need a link to a real, relatively reliable specification from which design something with the reasonable expectation that it should work with any modern cellphone with the 3.5mm 4-contact plug and draw a small but useful amount of power from it (microwatts).


texts: AC 50 Hz noise from an unplugged laptop?

texts:
I am now wondering how a laptop is powered when it is on battery. Let me give you some context: I am using a Mac Book Pro (with an aluminium case) for measurements with a very low signal to noise ratio. The signals are acquired through an amplifier, run on a battery, and grounded with an electrode on my body (impedance below 10 kOhm). The amplifier is linked through USB to the Mac Book Pro.
I noticed a very strong noise on the measurements, spot on 50 Hz, and very similar to a power line noise. The noise can only come from the Mac Book Pro for 2 reasons:

I'm inside a faraday cage with the macbook pro and the probes.
If I touch the casing of the laptop, i.e. if I GND the laptop, the noise disappear instantly.
Obvously, if I let go of the contact with the laptop, the noise come back.

I always thought that when on battery, the laptop was feed with DC current. Is this true, or does the laptop internally convert the DC signal back to an AC signal?
To solve my noise problem, I will obviously ground the laptop. However, I would like to know exactly what is causing this noise.
EDIT: A bit more context
To be fair, the application is still in development. Within the faraday cage were 3 laptops (one shut down) and about 4 phones. The amplifier and the amplifier battery were obviously within too.
The laptop used for recordings + the battery and amplifier are placed on a table.


texts: What is this type of screw head for accepting test hooks connection called?

texts: These screw heads are useful for retaining electrical connection with test hooks because of the two collars. What are these type of screws called?


texts: LCD default boxes not showing when contrast pin is hooked to old-fashioned regulator circuit

texts:
I have an HD44780 compatible character LCD display (2 rows 16 characters a row) powered with 5v through a regulator (4.97V according to voltmeter). If I connect a 2.2K resistor between the LCD contrast pin and ground and test the LCD, I get expected results of one row of boxes and the other row blank.

The problem with the simple approach is that when the battery voltage drops too much, the LCD screen fades accordingly. This is what I don't want.

I now replaced that circuit with the following circuit because I wanted the same contrast over a larger span of voltages. so that people can see an indication on the screen when the battery is low (instead of a fading screen)

So I tried this circuit with a 1N5224 zener (I think thats the model), but anyways, I measured the voltage across the diode and it outputted 3V  but then again I wonder if I chose the wrong diode.

I chose a 680 ohm resistor after the diode because the voltage is lowered and I feel choosing a higher resistor will make the display blank, but somwhow my math is messed up because with the parts chosen I still get a blank display even when using good batteries (to supply power to the regulator).

How do I adjust this circuit so that I get stable contrast on the LCD even when the power coming in is down to about 3 or 4V?


texts: Trying to understand clock circuit (wall clock, not signaling clock)

texts:
First of all, electronics is a new hobby for me.  I don't have any formal training, so please be patient with me.
Probably like many people, I picked up the interest after playing with Arduinos.  I have an IT background so programming an MCU came relatively easy (for the basics at least).  The more I get into it though, the more I want to understand how these things work at a more fundamental level.
I've been learning about basic concepts starting with the common components, and I've started to look at basic circuit concepts such as voltage dividers, power supplies (regulated, switching, etc), oscillators, and so on.
I've begun to look at reverse engineering basic applications (really just trying to figure out how I'd approach it or how other people have solved it).  That brought me to a typical analog wall clock.
There are a ton of videos and write-ups on how these things work, and I completely understand the gear and solenoid portion.  What I'm trying to understand is the actual solenoid trigger.  I ended up buying a cheap one from Walmart for $3 and some change.  After taking it apart though, there's a blob of epoxy or something covering what I believe is the key component(s).
I think I've hit a dead end trying to understand how I might re-create this circuit, but it seems like a crystal oscillator with a ripple counter might be along the right path??  What I get hung up on is that I paid $3.88 for the entire clock so I doubt its any sort of MCU, and I can't seem to track down any discrete components that get me anywhere close to the prices these things sell for (I'm sure economies of scale comes into play here though).  Also can't find components that'll work off of a single 1.5V AA battery.  Maybe the crystal/counter is the wrong direction?  (I understand that I could boost the voltage but it's unclear to me what that would do to the battery life).
Anyway, after all of that mostly superfluous info, here's my question:  Can anyone tell me what type of circuits/primitives I should be researching?  A schematic would be amazing, but really I'm just looking to get pointed in the right direction.  Even "look up this component..." or "search for these key words..." would be a big help.
Thanks!!


texts: Issues with Altium sheet entries and nested harnesses

texts:
I have several Altium schematics, with a harness going through several level of sheet symbols and ports. This harness contain another harness, along with a few normal nets.

The signals of that sub-harness are not properly connected.

So far, here are the symptoms:

Harness definitions match, there no harness definition errors.
The ports name and the sheet entries matches properly.
The ports and sheet entries harness type are identical.
The Design>Synchronize Sheet Entries and Port menu return "All Sheet symbols are matched"
There are no errors when I compile the project, except that the net that should be connected together contain only one pin.
After I compile and until I change something on the port or the entries, they show an error in the schematic editor, "Port not linked to parent sheet symbol" or "Sheet Entry not linked to child sheet"
Both the top harness and the sub-harness shows the errors of 6, but the pins are properly connected on the top harness.

I cannot share my documents, but I can post some small extracts. Let me know if you need more details.

What should be my next step to debug this issue?

Edit: This is a version of the project with only the problematic harness.

Edit 2: I could not make it work with connector-free harnesses, I don't know how to set a type for the sub-harness without the connector. To continue my project I uses a single level for the harness but I still want to know what the problem was...


texts: Calculate DC-Gain from step response at high frequency

texts: How can I calculate the DC-Gain at high frequencies from the above step response? Also, how is it different from the DC-Gain at low frequencies that is equal to 2?


texts: Total current in a closed loop using Ampere's Circuital Law

texts:
I would like to reassure my concept on this question:

I have 2 different ways to solve this question:

Determining the direction of current in the loop using right-hand solenoid loop and adding them up to get \$2I\$. With option C as the answer.
Because all the wires are in 1 closed loop with the same direction, we should just add them up together to get a total of \$6I\$. With option E as the answer.


texts: Best topology for a power Low-Pass Filter

texts:
I am in need of a LPF on a power line, something that carries up to 5A (at 36V). I am trying to leave the power transmission at DC unaffected, while suppressing noise components above 100kHz. I would like to power loss to be under a Watt, which limits path resistance at DC to about 40 mOhms.

My application is a mobile one, so I'm looking for a compact solution. My problem is that I have little feel as to the various filter topology trade-offs - particularly resulting size.

I (fairly arbitrarily) set my corner frequency to 100Hz, and would like to achieve 40dB of attenuation by 100kHz - a roll-off of about -13dB/decade or -4dB/octave.

My go-to LPF is a 1st order R-C circuit in Half-Section configuration. However, to achieve that DC resistance would require a chunky capacitor (30+mF).

Next, I looked at a L-C or L-R (of some order), or a Pi/T configuration, and I start to get lost in the options! So far, the most promising I see is the first-order L-C, but ... inductors are pretty big, too...

My question therefore is: is there a "typical" configuration usually used for such filters on power lines, where minimising size and DC resistance is more critical than sharp frequency roll-off? Is there a specific topology would usually be most appropriate here? Should I be looking at a completely different way to implement such a LPF?

I have assumed that any active filters are inappropriate for such power applications, but if there are suitable active filter designs/components, I'd like to hear about them...

Thanks!


texts: IP protected Enclosure and Conformal Coating

texts:
I have an aluminium Enclosure and I am trying to make it waterproof by using Silicone.

Is there any corrosion testing I can perform to Check Corrosion of
Silicone or aluminium: to check the integrity of my Ingress protection over some time?
Just to be on safe side can double protection
through Conformal Coating make sense?


texts:
I'm part way through my prototye macro keyboard which currently consists of 4 keypads with 16 keys on each - so 64 keys in total. The method I'm using is the 3 wire, resistor based one.R1,R2,R3 and R17 are 10k, R18 is 1M. (see circuit section below)
It all works perfectly fine, 64 keys using 4 analog pins on the micro controller (currently an Arduino Leonardo clone but it'll be a Teensy later) - So there's nothing wrong but I'm looking at reasoning for going the matrix keypad method which is what most keyboards have.
What are the pros of the matrix method over the resistor method. Pin count seems to be a big advantage on the resistor method 1 more pin gives me 16 more buttons. Pros and cons of each method?
5v1 is +5v
P1 is an analogue pin on the arduino
G1 is ground.
SB1A1 + SB1B1 are the 2 connections for button 1
SB2A1 + SB2B1 are the 2 connections for button 2
SB3A1 + SB3B1 are the 2 connections for button 3
etc


texts:
Capacitors in series have identical charges. We can explain how the capacitors end up with identical charge by following a chain reaction of events, in which the charging of each capacitor causes the charging of the next capacitor. We start with capacitor 3 and work upward to capacitor 1. When the battery is first connected to the series of capacitors, it produces charge -q on the bottom plate of capacitor 3. That charge then repels negative charge from the top plate of capacitor 3 (leaving it with charge +q). The repelled negative charge moves to the bottom plate of capacitor 2 (giving it charge -q). That charge on the bottom plate of capacitor 2 then repels negative charge from the top plate of capacitor 2 (leaving it with charge +q) to the bottom plate of capacitor 1 (giving it charge -q). Finally, the charge on the bottom plate of capacitor 1 helps move negative charge from the top plate of capacitor 1 to the battery, leaving that top plate with charge +q.

Why would inducing a charge of +q on one plate cause the other plate to acquire a charge of -q? I get that it would attract electrons from the other side, but the plates aren't the same distance from the electrons, so wouldn't the charge be less than q?

The following diagram might clarify what I mean. Its an explanation of why I think the charges on both plates aren't equal:

Please note I know that you can't use Coloumb's Law with plates. But Coloumb's Law allows superposition, so consider the above diagram to be the sum of all the individual point charges on the plates.


texts:
I have a 8 channel, 10A SPDT relay, which I'm having problems getting to work. Here are its specifications. I've attached a few images below for reference.

So, initially, I connected a 6V power supply to VCC and GND pins and supplied a 5V input signal to input 8. I checked the continuity with a DMM, and the Normally closed (NC) and Common (C) terminals are showing continuity before and after giving the control signal.
Then, I increased the control voltage to 18 V, but there's still no switching sound and no continuity between normally open (NO) and common (C).
I also tried increasing the the voltage to VCC to 12 V, still doesn't switch
I tried jumping the two GND pins and repeated the procedure, still the same results
Finally, I increased the VCC to 48 V and jumped the VCC and input 8 pins, the relay switched then. I heard the click and checked the continuity. But, the specs say that the control signal HIGH voltage is 2.5 V+. So why can I not get it to work at lower voltages?
I thought the relay might be bad and repeated this process with another relay, but even that's not being energised for conditions 1 to 4. (I did not check condition 5 for it)

I think there's a mistake in my understanding of how to wire/power relays. Where am I going wrong?

Thanks a lot!

P.S.: I did try all the 8 channels on the relay, but with same results.


texts: How can I determine LI-ion battery charge while varying the load?

texts:
I'm building an autonomous boat which contains a li-ion battery pack and I want to know how much charge it still left in it. To do this I measure the voltage of the battery pack. I let it run for about 14 hours and let it deplete and I get a nice discharge curve. So far so good.

But when I'm running this when the boat operates on the water, the voltage suddenly drops when the motor is switched on and jumps back up when the motor is switched off. And those changes also differ depending on how much throttle I give to the motor. The result is that the discharge curve is a total mess and it leaves me more or less guessing what the actual charge of the battery is in percentages.

The behaviour which I observe is also shown in this example I found of li-ion discharge curves:

So the behaviour I see is that my measurements switch between these various discharge curves. I guess I could make the percentage calculation dependent on whether the motor is powered. This method will be quite messy though. I also have to take into account how much I power the motor and when I change the motor, the battery or other parts of the electrical setup (which I do fairly often since I'm working on it) I guess I would have to manually recalibrate this whole calculation.

Does anybody know a good way to get a representative battery charge as a percentage when having changing power usage?


texts:
The circuit below will drive a 12v motor using an optocoupler.
In the circuit PC817 is used but how do you know which optocoupler to use?


texts: Why do batteries in series add up voltage?

texts:
This question will probably sound easy to most of you, but to me, it is still a kind of magic :)

Taking in account all I know until know, I guess a battery has two sides:

one that "emits" electrons (any technical term for that ?)
one that "lacks" electrons

So how can it be that when I put two batteries in series, they voltage adds up ? To me it sounds like the electrons from one should flow directly among the protons of the other.

Obviously there must be some kind of black magic there ;) Will one of you sorcerers explain it to me ?


texts: Illuminated rocker switch different wirings

texts:
In the following links the illuminated rocker switch power terminal is shown as one of the further terminals, and accessories terminal is in the middle (brass is ground or neutral).

http://www.learningaboutelectronics.com/Articles/SPST-rocker-switch-wiring.php
http://uk.rs-online.com/web/p/rocker-switches/0419782/
http://www.wiringdepot.com/blog/How-to-Wire-an-Illuminated-Rocker-Switch

Whereas in the following videos the power in terminal is the middle and the accessories terminal is one of the further terminal.

https://www.youtube.com/watch?v=6ndOlIgn1ys

https://www.youtube.com/watch?v=NpcqgZaqTjk

I thought switch wiring is standardized. Does it depend on the particular switch or one of the two methods above is wrong?


texts: How to use series resistors when connecting sensors to microcontrollers via SPI

texts:
N00b here; I have a sensor that I intend to connect to an Atmega 328P (AKA Arduino) running at 5V.  I already understand why I need to use a pullup resistor on the active low chip select pin, but the sensor datasheet also suggests taking care with the physical connections and specifically suggests the use of a series resistor between 470 Ohm and 1k Ohm for the MOSI line when using a 328P as an example (obviously chosen for us n00bs).  Given the wording, I expect that randomly picking a value in the given range for this one pin will probably not produce the desired results, and I further expect that this has something to do with the current consumption characteristics of the sensor, which are listed as 7mA typical and 8mA maximum.

I'm hoping that some more experienced designers can provide me with guidance here regarding which of the remaining pins (i.e. MISO, SCLK, ~CS) might also require series resistors, and how to calculate the appropriate resistor values (my guess would be to derive the value using a simple application of Ohm's law given the values 5 for the voltage and 0.007 for the current but I'm concerned that it may be more complicated than this).  Thanks in advance.

EDIT: sensor datasheet is here: http://www.first-sensor.com/cms/upload/datasheets/DS_Standard-LDE_E_11815.pdf
Seems like the info online is different in certain ways from the paper datasheet I have; I'll update this question when I have time to look at the circuit again.


texts:
I am looking for an eagle footprint that can accept both a standard 40 pin DIP socket or a ZIF socket. Alternatively, if you have tried this and found it to be impractical I'd like to hear that too.

update: thanks for the contributions. I had not realised that different brands of ZIF sockets can be very different in pin spacing. The ZIFs I have is marked 3M (although it is more likely a clone). The two rows are definitely not at the standard distance from each other, yet close enough to the standard distance that two holes is out of the question, the holes would overlap which AFAIK is frowned upon by boardhouses. I now made the holes larger, I'll see whether this works out OK (the file was sent to the PCB house today). The holes are now so large that no trace will fit between two pins, but the autorouter  did not mind :)

update 2: larger holes worked OK. It is a bit of a compromise now, I would never use such large holes for a normal DIP socket, but is still fits OK.

supercat's answer was the most usefull to me, but it is in a comment :( I have one of those black ZIFs too, I like it much better than my '3M clone', but it costed maybe 10 times as much...


texts:
I want to design a 1 GHz low-pass filter. I have tried to find a COTS lowpass filter at such high frequencies but I can't find one.

Hence, I have decided to design one using microstrip lines. So, can someone guide me through the process of designing microstrip based filters? or suggest any other alternative way to achieve this filter? I could not find a good tutorial online for the same. If such a tutorial exists, please give me the link.

Requirements for the filter:

Flat band response throughout the 1 GHz frequency range with a ripple of less than 2-3 dB.
Transition band of less than 50 MHz.
Attenuation in the rejection band of atleast 15 dB.
Attenuation in the pass band is at maximum 2 dB.
Input signal strength in the pass band is of the range of -10 dBm to -30 dBm.

Please note that I am not very strict on the above conditions but this is roughly the type of filter that I need.

Edit-1

This is the frequency spectrum of my input signal. I want to retain the information which is present upto 1 GHz frequency range. As you notice, the signal is already weak at higher frequencies, so the attenuation required at higher frequencies is much lower.

Please note that the photograph has been taken using a very bad camera, but the spectrum is from 0 to 4.5 GHz and hence 450 MHz/division on x-axis. The reference for the measurements in dB is 20 dBm and each unit on y-axis is 10dB.


texts:
I Write a program for receive data from Uart ISI, my Data Packet is something like :

2 first byte contain Device ID and type of command. Data is contain some bytes that could be have different length, minimum 1 byte to max 15 bytes, and the last byte represent the packet is finish.

Uart ISI code is:

volatile char UartFlag=Fulse;
volatile unsigned char count=0;
unsigned char coder[13];

ISR     (USART_RX_vect)
{
    coder[count]=UDR0;
    if (coder[count] == 20)
        UartFlag=True;
    else
        count++;
}

That receive each byte and save in coder. As you see when receive number 20, stop receiving process by UartFlag=True; and in main call a function DoSomthing(); to do something with coder as below:

while (1)
    {
        if (UartFlag)
        {
            DoSomthing();
            count=0;
            UartFlag=Fulse;
        }
    }

But I have problem that sometime the Data section have 20 in their bytes and its lead to i dont get Correct packet. I try to put \0 (the last byte=0 instead of 20) but maybe have same error.

I am looking for best way to find dynamic length of packet. What is the best way to find the dynamic length of packet?

A way that maybe work is put the data length in first byte of Data section, but it add extra process in sender device.


texts: Replacement IC for the touch-button QT1081?

texts:
A project I'm working on needs several touch buttons. I found the datasheet for the Atmel QT1081, which supports up to 8 capacitive buttons, with the added advantage for our circuit that there are separate outputs for each button, driven high when the button is pressed.

Unfortunately, this IC appears to be no longer available -- it's out of stock almost everywhere I've checked, and it looks as though it's been replaced by chips that use interfaces like I2C or SPI, which would complicate matters for our system, and require a redesign.

Does anyone know if there are other ICs around that support capacitive buttons, and which also provide a straightforward pin-per-button output?  Thanks.


texts: How is current split with two parallel LED's?

texts:
I have two LED's in parallel with different forward voltages, and want to know how much current flows through each of them. They have one series resistor connected before being split. Like so:

As LED's don't follow Ohm's law, I'm not sure how to calculate the current through each LED. I thought I should treat the LED's like voltage sources and apply KVL loops, but I'm still stuck.


texts: Can you offer suggestions for this voltage interverting circuit?

texts:
I have come up with this circuit, mainly through experimenting and trying things out.  It basically inverts Vcc into -Vcc (chiefly for using as a V- for things like op-amps and other such low-power things that require a negative voltage).
Can you think of ways I can improve on it?  One thing I have noticed is it doesn't much like low impedance loads on it - the output voltage across the load drops by a noticeable amount compared with a high impedance load (that may just be me though).
So any way, throw in your thoughts please (or close the question if it's off topic - I won't mind).

Update:
I just burned my finger on R5, so I have increased it to 1KΩ at the cost of a bit of output voltage...


texts: How can i use a 3 V LED switch in an application that requires more

texts:
i have a circuit which requires something between 5 to 7 V (DC) from its input , and i would like to add an LED push button to it , however i only have this DC 3V LED momentary switch , and im  sure if there is a way to use it in the application in where i can still see it lighting !!

Is there like a parllel approach to where i could keep the voltage level to the input but the switch would still work and lights?


texts: As we know that, everything is marketed as Low Power or Ultra low power. I understood that we can classify the controllers based on their application and clock cycle for the above mentioned sections. But what makes me little confused is what contributes to these facts of Low Power and Ultra Low Power consumption because the application basically demands the average power consumption. Then how MCU can be classified into these categories. Speaking from architectural point, are there any significant differences? I know it is a very basic question and can get points from Internet, but I didn't find sufficient explanation towards a customers point of view. It would be helpful if experts can give me some ideas about difference between Low Power & Ultra Low Power designs.


texts: What are my options for packaging a WLCSP IC as a DIP?

texts:
Hypothetically, let's say I have a chip in a super small WLCSP or BGA package that I want to have packaged as a plastic or ceramic DIP. No extra components; just the pads brought out to pins.
Are there companies that will do this on a small scale? Like 100 or 200 chips at a time? What might the setup and manufacturing costs be like?


texts: I think both of the Zener diodes in reverse bias and I think the output will be  4 V. Am I right? If I am wrong please explain the answer.


texts: Differential amplifier - transfer characteristic question

texts:
I have a question regarding differential amplifier's transfer characteristic.

If we have a circuit like this (note that \$V_{1}=-V_{2}\$, hence \$V_{cm}=0V\$):

the transfer characteristic for \$V_{out1}\$ and \$V_{out2}\$ looks like this:

Where \$k_x=-\frac{R_C}{2R_E}\$

But if \$V_1\$ stays the same and we connect T2's base (i.e. \$V_2\$) to the ground, then the transfer characteristic is:

Where \$k_x'=-\frac{R_C}{R_E}\$

And I can't figure out how this happens. In other words: how should I analyze the circuit to determine its output characteristic(s).

I think this might be helpful:

Thank you in advance


texts: In general, how does the functionality of a neural network scale as the amount of processing power is increased? For example, it seems reasonable that on certain tasks a "division of labor" can double the speed of response if twice the power is used. Is this true generally?


texts: So I have the below circuit simulation on LTSpice and trying to understand why whenever I set V3 Low or Hi I always get current through L1. M2 acts as an enable switch, so what I was expecting is that when V3 was high no current would flow, but that's not the case.


texts: Link Capacity and the Shannon-Hartley Theorem

texts:
I'm reading Computer Networks: A Systems Approach by Peterson and Davies. One of the examples demonstrates the relationship between link capacity and the Shannon-Hartley Theorem.

We can find the channel capacity by the formula:

$$C =  B \log_2 \left( 1+\frac{S}{N} \right)$$

In the example of the book, they define bandwidth of the channel to be 3000Hz and the signal to noise ratio to be 30 dB, which they say would imply that S/N = 1000.

$$C =  3000 \times \log_2 (1001)$$

However, I don't understand how a signal to noise ratio of 30 dB is equivalent to 1000? How is this worked out? It's not explained in the example.


texts: Are there any disadvantages to look out for when using Optiboot?

texts: Optiboot appears to be superior to the official Arduino bootloader in just about every way. Despite this, is there anything I need to look out for when using this bootloader? Common pitfalls? Different behaviors? Is it a feature-for-feature replacement? Essentially, can I switch to this bootloader and forget about it?


texts: Is output voltage of tps61041 adjustable by microprocessor

texts: This component is a step up converter. I am confused after reading the datasheet http://www.ti.com/product/TPS61041 . It says adjustable voltage upto 28V. But i am not sure if this can be hooked to a microprocessor. My objective is to feed 5v to tps61041 and get 0-28V in output from it based on microprocessor signal. Is this possible?


texts:
How do hard disk erase data?As far as I know, the hard disk stores data like this:

The write head contains a coil of wire with a core of iron.When current passes through, depending on the direction of current a magnetic field is created in the coil.

The surface of the hard disk is made of a ferromagnetic material. The magnetic field created in the coil magnetizes the ferromagnetic material. This magnetization remains.

A magnetized ferromagnetic material can lose its magnetization only by increase of temperature(Curie temperature) or if we hit it hard.

I guess none of those procedures erase data from a hard disk.How is it done then?


texts:
I am building a custom computer case into a 40mm grenade case however I am running into an issue with how to handle the DVI connections (need two of them). Ideally I would like to use a circular connector however I cannot find any useful information online on how many pins are required for a DVI-D cable or how difficult this task will be.

Does anyone have any advice on how I could proceed with this task?


texts: How can I measure the temperature wirelessly inside a piece of meat?

texts:
For a cooking experiment, I'd like to be able to measure the temperature inside a piece of meat while it's being cooked. Due to the mechanics of the cooking process, it's going to be difficult to use a wired temperature probe, so I was wondering if there's some way to do it wirelessly.

Is it possible to set up a thermistor, capacitor and tiny coil in some way that its resonant frequency could be measured, and thus the resistance of the thermistor could be measured wirelessly?

I'm especially interested in very small solutions which could fit into a slim spike which could be inserted into the meat. For this reason, I would also like it to be a batteryless solution.

Added:

Sample rate very low. I'd be happy with one sample per minute for Sous Vide, although one sample per second would be useful for frying.

The maximum temperature this device will have to survive will probably be about 80º just to be safe.


texts: Intermittent power dissipation calculation on TO-220 package

texts:
For a certain application I will be using this resistor. I might also go for this other resistor if needed.

The working conditions are:

Ambient temperature (max): 70 ºC
Power to be dissipated: 15 W
"On" time (max): 60 seconds

The selected power resistor is a 15 Ohm / 25 W TO-220.

The question is: is a heatsink necessary for a 60 second (max) operating time? Can I get away with a large enough copper plane? Assume that the down-time between operations is larger than the operating time.

If it was the case for continuos operation at 15W, I'm already aware of the need of a heatsink and how to calculate it, but I'm wondering how I should proceed for this "non-continuos" intermittent operation


texts: Calculating the frequency of a sinewave with the cutoff frequency, the input and output amplitudes of the sinewave?

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simulate this circuit – Schematic created using CircuitLab

I know there's a question similar to this on the website but that wasn't solved as not enough details were given.

It is a first order, low pass filter.

I have a corner frequency of 3000Hz, an input sinewave of amplitude 12.00V and output sinewave of amplitude 0.012V. I'm unsure as to how to work out the frequency of the sinewave.

Thanks in advance.


texts: How might I wire a split pi converter to transistors as to maximize output voltage?

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I was looking into various dc-dc converter designs, and I was interested in the split pi converter.

As a start, I just want to maximize the output voltage. I know in theory, the output voltage could be infinite, and in practice, it will be limited all the imperfections of the components I use. For now, I am just trying to better understand of how dc converters work. I have a basic understanding of how the buck and boost converters work, but I would really like to get a firm grasp on the split pi.

Also, would it be possible to get the same power transfer with BJTs as opposed to mosfets?

---100% speculation below this line---

I suspect there ought to be an optimum frequency that the transistors oscillate based on the capacitors and inductors used. I also suspect given an optimum transistor configuration, replacing some wires to the gates/bases of the transistors with resistors will yield an optimum configuration for for an arbitrary gain between input and output voltages. I also suspect that the ratio between certain pairs of these resistors will determine the gain of the system.