texts: Why are DIY PCB components placed at right angles?

texts:
I'm learning PCB CAD. I want to know why components seem to be placed at right angles and orthogonal to the PCB (assuming that it's rectangular).  Since the traces are secondary to the placement of the components, I'm not particularly concerned with traces. Why can't my TO-220 transistor be at 18.31 degrees to its decoupling capacitor? Why can't a ring of 13 LEDs be placed with each rotated by 27.69230769230769230769 degrees?

The thing that really confuses me, is the connector. It's pretty much irrelevant which way a resistor is placed alongside a capacitor on a PCB.  They only relate to each other. But connectors are different. They relate to the outside world which is not entirely orthogonal. If I have a triangular bedside thingy, I might want connectors /controls on all three sides. So at 120 degrees to each other. This might also have an effect on the traces if close to the connector pads.

I don't personally think that there is any issue with components at any angle. You just never see them, even at the school level. Why?

Three pointers:

I'm only concerned with DIY projects. So no component auto placing
by cyborgs operating to standard programs/industry norms.
There is a similar question from 2010. That is broader in scope
than mine as it does not restrict the manufacture to DIY-only
projects. And six years in CAD / software development is a lifetime
and rarely relevant. Software that is easier to design in 45 degrees
steps is not a necessarily still relevant. If I use Illustrator,
Blender, AutoCAD or Inkscape there are no restrictions on angles.
I'm making a distinction between the orientation of traces and the
components themselves.


texts: Designing for DC voltage drop in low gauge wire

texts: Are there any types of DC low voltage power supplies on the retail market that can accommodate for long wire runs (18 gauge wire). I am worried about voltage drop and power failure; I'm trying to power window shade motors with 18 gauge wire over long distance wire run and I need 18 volt output.


texts: Isolated Circuit - Understanding and Intuition

texts:
Consider the circuit (pictured) taken from Sedra and Smith (they use it as a model for a voltage amplifier, but that's besides the point). I've done a number of circuit analysis classes and from those I know (or so I think) that no current can flow between the two "halves". However, I'm hoping someone can clarify the following:
(1) Is there any formal terminology for such a circuit? Is it an "isolated" or "independent" circuit?
(2) Can someone argue by contradiction as to why current cannot flow between these two halves? I've thought about this myself, and the answer is easy if all circuit parameters are constant (because then we would get all the current building up in one side, or blowing up to infinity, after enough time). But in the case of time-varying circuit parameters I'm struggling to convince myself that it's impossible that current could ever flow through that bottom branch. That is, I'm not convinced that there is no contrived way to concoct a situation where current might flow between (and perhaps back again) the two halves seen here. Maybe it's not impossible?


texts: Underdamped RLC with CCCS, calculating capacitor voltage

texts:
Referring to "Electrical Circuits" Nilsson/Riedel 10th Edition.

I have a classic underdamped RLC circuit with a CCCS (Current Controlled Current Source) with a current multiplication factor of \$\beta\$. I want to find \$V_c(t)\$
In the attempt I end up with this equation:
\$LC \frac{d^{2}  V_c}{dt^{2}} + RC \frac{dv_{c}}{dt} + \frac{V_c}{\beta} = V\beta\$
which doesn't look like equation 8.66 in the book which is for RLC without a CCCS:
\$\frac{d^{2}  V_c}{dt^{2}} + \frac{R}{L}  \frac{dv_c}{dt} + \frac{V_c}{LC} = \frac{V}{LC}\$
So I'm a little bit at a loss in how to find the solutions from here.
Updated:
Going way back in my notes I (re)discovered that
\$\beta=e^{V} = 1+\frac{V}{V_c}\$
Which now gives me this equation
\$LC \frac{d^{2}  V_c}{dt^{2}} + RC \frac{dv_{c}}{dt} + \frac{V^2_c}{V_c\ V+V^2} = \frac{V\ V_c}{V+V_c}\$
But now I'm stuck again


texts: Does Sallen-Key filter need a high impedance load?

texts:
I am using the circuit below to monitor the output of a piezoelectric diaphragm, represented by a sine wave generator and capacitor C3.

The circuit is powered from a split supply (+5V/-5V) derived from a linear power supply (230V, 50Hz). I need the full rail-to-rail dynamic range (or as close as possible).

The functions of the amplifiers are as follows:

U1 - charge amplifier, frequency range of interest: 1Hz-60Hz
U2 - Sallen Key filter, low pass, fc = 110Hz
U3 - scale and bias amplifier to convert U2 output to 0V min, +3V
max, suitable for ADC.

The circuit works in simulation, but in practice I find that a high amplitude mechanical impulse on the piezoelectric disk causes U3 to oscillate'. (U3 seems to output the input plus narrow pulses which jump to the +5V rail at a frequency of 50Hz). The oscillation will eventually disappear (after about 30-40 seconds) if the piezo is left untouched. I checked the power supply rails - they are clean with little ripple, even when the oscillation is happening.

If I disconnect U3 and monitor the output of U2 only, the problem is not present. I found that I could "cure" the oscillation in the circuit by putting a voltage follower amplifier between U2 and U3 and then reconnecting U3. I'd prefer not to use a voltage follower op amp as it introduces additional noise.

My question is: Does U3 cause a problem for the stability of U2 at high frequencies? The impedance of C101 will be low for a high frequency impulse on the piezo disk and U2 is trying to drive current to support this as well as maintaining the correct current through R5 to keep the input voltages on pin 2 at around 1V d.c.

Perhaps there's a better way to offset the output signal?


texts:
I'm trying to solve a question concerning performance. I have the final answer (24 * 10^9)but I can't determine how to get there.

I know the formula for performance is

Execution time: CPI * I * 1/CR
CPI = Cycles Per Instruction
I = Instructions

Question:
Determine the number of instructions for P2 that reduces its execution time to that of P3.

The first step should be to find out the cycles per Instruction for P3. The equation would be:

  8 = 1 / (2.5) * CPI * 40
  8 = 1/ 2.5 * CPI * 40
  8 = .4 * CPI * 40
  8 = 160 CPI
  1 =                80 / 16

I know the answer here should be 0.008 CPI, but I don't understand how to get there. 2.5 * 40 would be 100, but it doesn't make mathematical sense to me. What am I missing? Thanks.


texts:
I'm tring to build an audio amplifier. I decided to use a basic common emitter amplifier circuit as a starting point. Here it is:

I have some questions about the circuit.

1-) What transistor can I use in this circuit?

Results of DC analysis:
Vce = 10.06V and
Ic = 1.26mA (I guess, these values will be used for choosing the transistor.)

2-) What's the output voltage of a standart mp3 player? Can it be 300mVp as I read somewhere?

3-) When I assume ß = 150 and input = 300mVp , the output is -2,13Vp . I guess it gives 1w power to speaker. Is there something wrong?


texts: Is one accelerometer enough for detecting tilt/orientation of a rigid body?

texts:
I posted this question earlier in physics.stackexchange, but I think this is actually the best place for it.

I’m not familiar with sensor hardware, and I don’t really know how an accelerometer works. But I do know that from a mathematical point of view, you wouldn’t be able to uniquely determine the orientation of a solid object knowing only the acceleration of one of its points.

Indeed, assuming known initial conditions and acceleration function of one point, say point X, one can solve the second order ODE and get the position function for that point, but that wouldn’t determine the position of the rest of the points in the solid object, because the object could perform a rotation centered on point X, leaving it unchanged.
Despite all that, I have seen several claims that modern mobile phones benefit from the inclusion of accelerometer sensor in such a way that enables them to, for example, determine the orientation of the screen. I don’t understand how an IPhone would know to what position the screen was tilted. Consider the following example where the red dot indicates the location of the accelerometer sensor.

Suppose acceleration data was processed and the motion of the sensor was determined as the red arc shown in the pictures below. How one could distinguish from the two depicted motions? Notice that the final orientation of the device is different.

Please note that by one accelerometer, I mean one that would be able to register accelerations in all 3 dimensions. That way, upon integration I would get the spacial (3D) trajectory of the point. I believe the issue I describe here holds even in such scenario.

Thanks for reading!


texts: BTA16 absolute maximum amperage at 220/240V 50hz and impact of snubbers on resistive loads?

texts:
Using a BTA16 600CW3 triac with the arduino uno with the following schematic.
Can it derive a 1.5 ton Air Conditioner and what is the absolute maximum amperage and power it can handle safely at 220/240V. I am attaching the circuit for the fan dimmer I am using (inductive loads). All the resistors to the 240V are rated at 1 watt.
Neglect the zero crossing part, I wont be dimming it for the Air Conditioner. I just wanted to know whether the switching part can handle the current. And what is the max current it can handle? The datasheet says that it can handle 16A at 600V but I am not sure.

And I will also like to know (as said many a times that the snubbers are necessary) for inductive loads. What impact do they have on the restive loads.
If I am unsure what type of load is to be connected than can I connect the snubber to the triac?


texts:
I'm trying to interface my Arduino Uno with a typewriter (smith-corona sl 460) I picked up in a garage sale a year ago. My final goal is to make it so I can type in something on the serial monitor on my computer, and have it come out via the typewriter. I'm going to try to do this by wiring the output pins on the arduino to the keyboard input pins on the typewriter. However, I can't make heads or tails out of this cable coming from the keyboard, and if there are any silkscreen labels, they are on the other side of the board, which I don't want to flip over - I still want this thing to be operational if the hack doesn't work. How would I go about figuring out what line of the cable did which? I have, as I said, an Arduino Uno, as well as a multimeter, and a fairly basic pocket oscilloscope, with no digital analysis or even that much memory past a capture function. If I'm trying the wrong sort of approach for this project, please let me know.

A picture of the cable and the microcontroller:

A picture of the whole board:


texts: Why cellular modems (still) need a SIM card?

texts:
I'm designing an embedded system that will require a cellular modem (3G). I never used one but the designs I came across with they all use a SIM card slot.
I understand that this may be convenient but isn't there a way to avoid it? Why and how? What are the challenges of storing the information stored in a SIM card in any other kind of memory such as the internal memory of a microcontroller?

Thanks


texts: Under open-circuit conditions, does a transformer behave more like a resistor, capacitor, or inductor?

texts:
I have the below schematic showing the equivalent circuit of a transformer under open-circuit conditions. Will the transformer behave like a resistor, inductor, or capacitor? And will this behaviour vary depending on the values of the open circuit current, open circuit voltage, etc?

I notice that we have a resistor in series with an inductive reactance, which is then in series with a parallel combination of a resistor (representing core losses), and a magnetising inductive reactance.

So far, I have ruled out the transformer behaving as a capacitor. I am thinking that perhaps the transformer is behaving as an inductor? Although, I do not have a great understanding of why this is, it's really just a wild guess.

I appreciate your time and help,

thank you.


texts: Is there an ideal PCB trace width for data lines?

texts:
For a 1oz FR-4 PCB, is there an ideal PCB trace width for data lines?  For power supplies, I realize wider is usually better, and power planes are preferred.  But what about data lines?  Is narrower better?  Should I simply just use as narrow as the PCB fabricator supports reliably?

I've heard some advantages of using narrower PCB traces, but want to verify:

Narrower lines results in higher resistance, which lowers the likelihood that series resistors are needed, and reduces EMI compared to wider lines.
Narrower lines allow for easier routing, i.e. between other tracks and pads.

Any disadvantages?

Are there uses for different widths for different frequencies -- i.e. SPI/i2c frequencies versus MIPI/USB frequencies?

I have been using the default of 10 mils...that seems kind of too large.  Any width to use as a starting point/default?  Perhaps 5mils or 6mils?  If I use 6 mils, should I also use 6mils minimum trace to trace design rule?


texts: What's the best ground topology for this mixed signal board?

texts:
I'm designing a 4 layer mixed signal PCB with sensitive analog circuits and RF-digital circuits. The board have many mechanical constraints so the places of the analog and digital circuits are fixed.

When designing the ground plane I added some ground cuts. The idea was to make the digital return currents flow seperately under the analog return currents without disturbing the analog currents:

Is this a good grounding?

Is this a good idea / necessary to seperate the ground using this ground cuts? In the return path of analog currents, there are no sensitive components. But without the ground cuts, the digital and analog return currents would somehow "collide". Thus, the analog ground would be noisy. Are my considerations correct?

How to achieve the star topology?

The seperation of digital and analog grounds with a bridge under the DAC is the recommended way. But then I would have star point right under the ADC. However, my DC-Jack is far away from this point on the top left edge. And the path from the ADC to DC jack is going over the digital SMPS. And the ground of this SMPS is not connected to the ADC but it would return directly to the DC-Jack above.

I could connect the digital SMPS ground directly to the star point under the ADC, and then connect this star point to the DC-Jack=>But this looks very strange to my eyes. I didn't see designs like this.

What do you think, what would be the best grounding for this board?


texts: High Power H-Bridge with IR2125 Drivers Problem

texts:
I'm currently stuck on a problem when trying to drive a 140V DC motor using an H-Bridge with 4 high-power mosfets and 4 IR2125 drivers.

I'm using as input to the drivers a signal generator of 5V in PWM with a duty cycle of 80% at 30kHz. The applying to the mosfets Q4 and Q5, nothing happens. What I could do is bypassing the high-mosfet on the left (by connecting one terminal of the motor to VDD - M1 to VDD), and then only switching the low-side mosfet (Q5).

But with this configuration obviously I get no direction control of the motor! I don't understand why I'm not being able to turn MOSFETs Q4 and Q5, or Q3 and Q6 as a normal bridge configuration would do. I'm not sure if this has something to do with the fact that this driver accepts only PWM as input.

PS: In my circuit I've shorted the input of the drivers that control mosfets Q4 and Q5. Same for inputs of drivers that control Q3 and Q6.

The extra-circuitry around the drivers was taken from the application note of the chip. In the circuit VCC is 12V, VDD is 166V, VSS is floating.

Attached is a picture of the bridge I've built. Thanks!


texts: When to store parameters to flash/eeprom of an MCU

texts:
I wish to use the MCU flash for storing non-volatile information such as tuning parameters. Is there a known 'best' policy of when to store these values...i find a few options and would like to get your view on them.
a) Run a task for writing parameters to flash
b) Write to flash during shutdown routine. (but what happens if a sudden shutdown happens)

Also, how to decide whether parameters should be read from flash or from the default code. Once a parameter is changed by the user (it is different from the default value), every following init will need to read those parameters from the flash...right? I want to know how the experienced folks deal with these issues?

Thanks and best regards,
Vishal Sapre


texts: Does converting 12V DC to 110V AC really increase the available watts?

texts:
When designing solar panel systems for homes how do you convert the watts generated by the 12V DC solar panels to watts available in a 110/120V AC system? When I do the math it seems to defy logic.

Watts = amps * volts (which also means W/V=A) is the basic formula. So what is wrong with the following:  The solar system generates 100 watts at 12V DC = 8.33 amps. Now I want to use that power that has been generated so I feed the power into a 12V DC to 110V AC inverter.  When I multiply the amps produced of 8.33A by 110V I get 916.3 watts. I always thought that a watt was a watt (minus power loss due to resistance and inefficiencies of your circuit design of course) so do I really turn 100 watts DC into 900 watts AC?  That seems to defy logic. Or do I still have only have 100W 110V AC and why?  Am I overlooking a formula that should be included when Inverting DC to AC?

If my math is right then why do they say that I would need a 5kW 12V DC system for my home? That would convert to 416 amps and a 45.8kW 110V service in my home when the solar is at peak performance. (I know that I would get no power at night).  My average hourly usage is 2kWh so it seems that 46kW is WAY overkill even if I save some to batteries for night time use.


texts: Drive LEDs in a bar from an amplifier output?

texts:
I'm working on a small-scale audio spectrum analyzer. I take an aux cord L/R inputs into two amplifiers that output to a speaker. Say I pass the output that goes into the speaker into 3 bandpass filters for low,mid, and high ranges.

If I then rectify that output to a DC voltage, how would I configure a "bar" of LEDs to light up based on that voltage? Say I had 6 LEDs per bar. When there's little to no bass I want only the first 1-2 LEDs to light up, and when there's a lot of bass all 6 LEDs to light up.

I'm trying to this project with only analog components, as I realize this is a trivial task with a microcontroller.

I'm not sure if it's important or not in this type of circuit, but other than the signal output I have access to a 5V DC source that I've mainly used to bias the amplifier.

I can't quite figure out how to configure the LEDs in such a way that it matches the behavior I desire. I've searched around online and see some circuits use zener diodes to achieve this sort of effect. I think I want to turn the LEDs on through current and not voltage but am unsure how this works. I breadboarded some LEDs and played around and I couldnt get the right behavior.

EDIT:

As duskwuff pointed out below, the LM3914 is a great and pretty easy solution to this problem. But I hate easy. I've been messing around more and here's what I've been trying to do:

1) Rectify my signal output using a full wave rectifier. There's a problem with this though, my amplifier output signal has a minimum p-p of around 200mV. This means that at lower volumes, no signal will be rectified because the diodes will not allow current through. Could I possibly solve with with an amplifier stage between the output and the rectifier input? I have a 5V DC source available.

2) At this point I'm trying to figure out a way to use NPN transistors as switches that turn on at different rectified output levels. My success with this has been, well, very limited. At first I tried using Zener Diode's taking advantage of their zener voltage, but I looked around and I can't find any with a low enough Zener voltage that would work here. I could put an amplifier between the rectifier stage and the NPN stage, but I'm not sure thats the best solution.

I've included a picture of my entire circuit schematic so anyone can see what I'm working with here.

Starting at the far left I have a balance control, followed by a 3-stage amplifier, followed by a rectifier.

Any help would be appreciated.


texts: Are base resistors of any use for a high-side NPN switch?

texts:
I "inherited" a small project from a person I don't know, and I'm navigating my way through it. It's a small gadget featuring a 7-segment LED display. I hear the device's original designer is more of a hardware guy (the very messy, copy-pasta code hints in the same direction). Thus I'm inclined to think his schematic is something I can learn from, but there are a few things in there which I find puzzling — one of which is this:

simulate this circuit – Schematic created using CircuitLab

Which looks simple enough:

a single MCU pin cannot drive 7 LEDs directly, so you need a switch transistor;
you can use either a PNP or PMOS (proper high-side switches), or NPN used as an emitter follower (the anodes only "see" ~4.3V, which is acceptable). He chose the latter, probably because he had a bucketful of NPNs laying around;
"it's a bipolar transistor, it needs a base resistor"

Question

The 10k resistors seem to be redundant, you can replace them by wires and get a pure emitter follower. Can they serve any reasonable purpose in this situation?


texts:
The markings are:

1112
 1Z

The package is 2010 (5025 metric).
Any clues will be much appreciated.

Apparently it is located right at the 12V input. On DMM / diode test - it measure same in both diections, so I gather it is most likely dead. LM2596S gives 0V on the output (5V variety). This is all I can tell, I am afraid. Sorry for poor quality images.


texts: Given the system function, how can i tell if it is a lowpass or a highpass filter?

texts:
If i am given the system function of a FIR digital filter obtained by recursive

frequency sampling design procedure., how can i tell if it is a lowpass, highpass, or bandpass filter?


texts: Optimization voltage divider measurement

texts:
How to design a voltage divider to optimize the measurement error?

Intuitively I would take the same ratio $$\frac{load}{divider} = \frac{divider}{measurement}$$
As follow: the voltage is roughly divided by 5. The divider induces 1% error on the load, and the measurement 1% error on the divider.

Is it a good practice?

simulate this circuit – Schematic created using CircuitLab


texts:
How do I calculate how long a battery operated product will run?

Here's what I've got:

2 AA, 1.5V, 2700mAH batteries
Voltage Regulator with a Iq of 25 uA
Voltage Regulator Eff = 80%
Active Current = 50mA
Sleep Current = 1uA
Duty Cycle = 99.9% (only active 0.1% of the time)
Active Voltage is 3.3V

I've gone the current route and got an answer.  I went the power route and got a TOTALLY different answer (days vs years different).

How do you do this?


texts: Has anyone had to sign a form from Mouser before an order was allowed? (Nucleo Board)

texts:
Not sure if it's exactly the right place but here it goes.
I was ordering a STM32 Nucleo board for the first time (the NUCLEO-F756ZG), along with other parts as I'm working on my own project for one and wanted to get into using the STM line (just graduated and didn't get to learn it in school.)
To my surprise today I opened my email and was told that my order is on hold until I sign a form that has to be sent to an export department.
It's asking for my personal info such as my Federal Tax ID #, if I've ever been convicted of any crimes like export violations, or if I'm on any lists, what I intend to use the product for, etc.
What gives? I haven't been able to find anything online about this with anyone else ordering these boards. I live in the United States.
Is this a normal thing or is there some mistake? I don't want to be on some list for just trying to learn something.


texts: Why does temperature modify the characteristics of a diode?

texts:
Everyone knows that temperature affects every semiconductor device you can think of, and diodes are no exception.

From the below graph, we can see that the temperature has marked effects on pn junction diode and zener diode.

PN Junction diode

Zener Diode

Source : Concept electronics

  Now we can see that in an PN junction diode,in the forward bias region increase in temperature causes decrease in the cut-off voltage,whereas in the reverse bias the opposite thing happens.

I know that these can modeled using the diode-current equation.
But conceptually I can't understand what happens to the charges with change in temperature which causes these change in the characteristics.

  I also can't understand why the zener diode behaves differently from that of the junction diode in the reverse bias region.Please explain me this too conceptually.


texts: Servo Vs Stepper for a high accuracy project

texts:
Im trying to build a weird idea for academic purpose. Trying to control a real car using joystick. So for the steering purpose and accelerator pedal, without modifying any internal mechanics, what Im trying to do is to attach a custom device to accelerator pedal and steering column so that it will physically pushes the accelerator using that motorized attachment.

So here are my concerns. With my very little knowledge in motor and these mechanical areas, Im really got confused which is the best motor which serves the purpose. Servo or Stepper. I dont know about these Nema rating as well. So with some theories does Nema 17 does serve the purpose?

Also for both steering and accelerator we should have to hold the positions in some state for some time. So as on considering all these factors Im requesting a good suggestion


texts: When shall a current output DAC be used?

texts: It seems to me that voltage output DAC can do all the jobs of a current output DAC. When shall a current output DAC be used(superior than voltage output DAC)?


texts: Are there any problems with my circuit design?

texts:
I am new to designing circuits but I have spent a lot of time researching for this project. I have been designing an automated indoor garden for my home. To save space, there will be 3 gardens stacked vertically. The gardens will be self watering using moisture sensors, a pump and solenoid valves. It will also have blue and red LEDs to provide light to the plants.

Here is the link to a google doc of my project for more details:
https://docs.google.com/document/d/1jLP35pS16meeRFSbU6V1jtvDDfdHTNM6jPjyyabYSCg/edit?usp=sharing

I have made my circuit using an electronic circuit simulator I found online. Here is the link to it:

Circuit

As you can see, I am using 1 pump, 3 solenoid valves (indicated by the green light), 15 blue LEDs, 27 red LEDs, and a laptop charger as the power supply(20V, 4.5A). To control the pump and valves, I am using transistors and an Arduino UNO.

The idea is that the moisture sensors will detect when each level of the garden needs to be watered. When a level of the garden is too dry, the Arduino will send power to the pump to turn it on. The Arduino will also send power to a specific valve to allow water to flow to that level of the garden.

Component Data:

Transistors

Valves

Pump

LEDs

So the question is, can anyone see any problems with the circuit before I actually build it? I am pretty new to electronics so I am worried I am going to damage some of my components.

A more specific question I had was, am I representing my pump correctly in the simulation? I have used a resistor to represent it. Should I be using a diode like I did for my valves?

Please let me know if I need to provide more information. Any feed back I receive will be greatly appreciated! :)

UPDATE

Thank you for all your wonderful suggestions! :)
I have used your suggestions to change a few things. I am splitting the watering and lighting portions up into 2 separate circuits, each with their own power source. The watering side will be using a 12V power source, while the LEDs will have a 20V power source. Using separate power supplies also gives me the option to add additional levels to my garden in the future since I no longer have to worry about going over my power supply current rating.

Here is the link to the updated simulation of the watering circuit

I am going to wait until my LEDs arrive in the mail before I design my circuit for them. Since they are from china, I want to test them to see what their specifications actually are. I am also looking into current regulators for them.


texts: Does leaving a barrel jack on a 9V battery drain the battery?

texts: This is for when the barrel jack isn't plugged into anything. Just attached to the battery.


texts: How does a laser printer control the laser to produce such high resolutions?

texts:
I opened up a broken laser printer yesterday to find one of the important sections (this is an example photo from Google Images), trying to learn from the design of the laser+polygon mirror motor within:

I was able to find the pinout of the driver chip, and successfully got the motor running at a very high RPM, as well as the laser to reflect off the rotating mirror, forming a simple linear pattern on the end surface.

Now, here is the part that's mysterious to me:

The mirror is just a standard BLDC (not a stepper nor an encoder-based servo).
The hexagon of mirrors is rotating at unknown/inexact speed.
There is such a high speed of rotation and such a short mirror length (I measured each side of the hexagon's mirrors to be about 2 cm long).

So how do they control the laser to reflect at the exact rotation-timing/angle of each mirror so as to (hit the photoreceptor drum at highly accurate positions and) produce printing quality in the thousands of DPI, i.e. better than 0.03 mm resolution?

In other words, how is the timing of the on/off laser pulsing coordinated with respect to the mirror angle in the below picture?


texts: What happens when bjt beta infinity? Is it in saturation or cut off or active mode?


texts: Why are capacitors high-pass / low pass frequency elements?

texts:
I'm trying to study for my intro circuits class final and always found the idea of impedance and filters confusing.
Take these two circuits:

The first confusion is where are we even measuring the voltage across from? Voltage across the capacitor? Across the resistor? Is there some kind of convention we normally measure on?
Finding the impedances we get:
\$ Z_C =  \frac{ \frac{1}{jwC} }{R + \frac{1}{jwC}}  = \frac{1}{RjwC + 1}\$
\$ Z_R =  \frac{ R }{R + \frac{1}{jwC}}  = \frac{RjwC}{RjwC + 1}\$
(where \$ w \$ is frequency and \$ j  = \sqrt{-1} \$)
The impedance \$ Z_C \$ increases as we decrease frequency, so the voltage drop across the capacitor decreases when frequency is low. Doesn't that mean that the capacitor is letting through all the low frequency signals... Why is the lower picture showing us that all the high frequency signals are going through the capacitor?
So shouldn't the capacitor be a high-frequency blocking element? Why is it known to be a DC blocking element then?


texts: Trying to find this specific manufacturer for a diode

texts: I am trying to find these specific diodes and who made it. Thanks for your time in advance. They could be tvs diodes also


texts: Is it fine to have different number of input/output port in module and module instant in verilog?

texts:
For example if i am going to model T flip flop using D flip flop. I am not writing the whole code of T flip flop as here it is not related to my query.

module T_ff(q,clk,clear);
//...............
//Instantiate the D flip flop
D_ff dff(q,~q,clk,clear);
endmodule

// edge triggered D flip flop
module D_ff(q,qbar,d,clk,clear);
//..............
endmodule

The number of input/output ports are different in Instantiate of D flip flop (define inside the T flip flop) and in module of D flip flop. Is it fine? Can it result in error?


texts:
My proteus library is empty even though the folder is available, I have tried all the fixes on youtube (which are all the same).
when I click parts, the whole library is empty, I use proteus 8.10 sp3


texts: Is it a good practice to put multiple capacitors in series to obtain higher voltage rating in medium voltage system?

texts:
I am building a DC link for an IGBT based inverter.

The input is provided from a 400V 3 phase AC source. I couldn't find capacitor  rated greater than 450V in my nearest stores.

I'm thinking of designing a filter with two capacitors in series.
I am using 330uF 450V capacitors. The capacitance requirement is less than 165uF. That is, I am OK with halved capacitance.

Is there anything else I need to consider or should I proceed with this design?


texts: Identify specs of this filter coil and enable independent use of PSUs fed through it?

texts:
Shown in the pictures is a power supply and distribution system from an old Fuji Xerox all-in-one copier/printer/binder/etc.

In the image that shows multiple components you will see the components laid out with red arrows indicating the connection path from mains in to the 3.5v and 5.5v PSUs. All black and white wires are AC.

Note: The 24.5v PSU and the Filter Board are NOT fed through the Filter Coil. ( I have traced the circuits.) Only the 3 lower-voltage PSUs are fed by it.

Those 3.5 and 5.5v PSUs are each 8A output supplies. Fittingly, the Filter Coil has very heavy gauge copper as its winding, and has these markings on the top:

"104E94220" and TAM 4KO3K"
I am interpreting the O as an "oh" not a
zero based on comparison of zero in top line with O in bottom
line (see picture).

Googling the part numbers of the coil has been no use. Proprietary/custom part.

So, to my question(s):

Can I test to determine the properties of this coil, and how do I do that?

Can I divide that/those specs into thirds to determine what coil would suit each of the three PSUs that were fed through it? (To create standalone power supplies.)

Alternately, just good advice on what filter coil to purchase to place in front of these PSUs would do, though improving my understanding is always better.

EDIT:

Added a screen cap of the circuit from the engineering handbook for the original device. The coil is circled in red. The machine was on 230V mains before deconstruction, which by the diagram means there should be a resistor there? Gotta admit I'm very confused by that. A coil is a resistor? Can't be can it?

ALSO- The picture of all the components has the Mains straight to the board, but it actually goes through the Filter Block before going to the distribution board. Anyway, hope the new info helps.


texts: Large NFC/RFID reader antenna around a screen

texts:
I would like to have an NFC/RFID reader with a screen around 7", where one could tap the card anywhere on the screen to have it detected/read.

I do not need to know where the card was placed (contrary to this question for instance), just detect/read the card anywhere on the screen.

I understand there are such antennas for smaller screens, like Pulse Electronic's  W7002, but it's only suitable for screens up to 5 x 7 cm (about 3 inches).

What are the possible issues with a larger antenna surrounding a 7" screen? It would be about 160 x 70 mm.

My understanding is that optimal communication between the reader and tag occur when the two antennas have roughly the same size. Here the target tag is a standard Mifare card, so the antenna is usually roughly 75 x 45 mm.

Some of the questions/answers such as this one focus on getting a larger range (distance between antenna and tag) by expanding the size of the antenna, but in my case, I'm more interesting in increasing the area rather than the distance.

Another issue I wonder about, is what would be the effect of the presence of the screen in the same plane as the antenna? Since this is going to be a touch screen, the screen should should be just below the touch panel glass, so the antenna will be in the same plane. Would having a ferrite "ring" around the screen (between the screen and the antenna) be useful?

Alternatives could be:

Placing the antenna behind the screen, but many (most?) screens have a metal shielding on the back, so this would probably be ineffective. Even without shielding, I believe backlights often have a reflective surface at the back to avoid "losing" any light, which is probably metallic as well?
Placing lots of small antennas all around the screen, though I'm not sure one would reach the center of the 7" screen this way, and opens up a lot of issues like switching between readers/antennas so only one at a time is running
Using Sharp's transparent antenna method, but this is probably a bit out of reach, not to mention patented, and Sharp's NFC-enabled screens to not seem to be on the market yet.

Any feedback or ideas welcome!


texts: How do I measure a voltage greater than 5 V with Arduino?

texts:
I want to measure a varying voltage with an Arduino and real time data plotting has to be done.

But the supply voltage will be 10 V and the Arduino is not supposed to have more than 5 V.

Is there a way I can solve this problem?
Do you have any recommendation for the circuit design?

simulate this circuit – Schematic created using CircuitLab


texts:
I'm new to electronics and this is my first post so please be patient with me.

Introduction

I am required to design a rehabilitative exoskeleton-like knee-brace to assist sit to stand, I have faced a number of uncertainties due to lack of understandings of the working principles of a motor. This exoskeleton should exert minimal torque to assist the user to rise from sitting

As a rehabilitative device, the output speed of this motor is required to be constant and from what I understand, holding the Voltage input to the motor constant will achieve that. The motor needs to have a controllable output torque, and I can control torque by controlling the armature current.

In theory, with a buck converter, I am able to hold the input voltage to the motor constant. This would be able to hold the RPM constant but leaves the torque uncontrollable. However this would only leave one output parameter to be variable
I have also thought of connecting the buck converter to a DC motor driver as I understand that the buck converter can only control either Voltage or Current and not both simultaneously, the DC motor driver should help keep the RPM constant with a varying Voltage input while the buck converter would help to vary the Torque with a controllable Current output

Question

Would this be a feasible idea or are my principles extremely wrong, I would like to seek advice before sourcing for parts. I hope no one feels that I am asking to be spoon-fed, as I am only asking for advice


texts: Why would a multimeter (ammeter) connected in series prevent the instrumented device from powering on?

texts:
I'm trying to measure the current used by a 3.5" hard drive in an external enclosure.  I connected my multimeter in series with the positive 12V power supply, but in doing so, the hard drive fails to startup.  It tries to startup (I can hear mechanical movement) but quickly aborts and retries cyclically without success.  During this process I can measure about 350mA of current (on the 10A meter setting) and a stable 12V -- of course, the device works fine without the multimeter in series.
I'm wondering what might cause this phenomenon and if its common or well-understood in general.  I've tried with two multimeters, both of different grades and observe the same results.  Could there be an in-rush current limiting device in the multimeter which is impeding a high-current demand of the hard-drive?  The hard drive would draw the most current during the acceleration of its motor, which typically happens during startup.
I don't have a clamp meter, but I suspect using one would be best for this application as it removes the physical connection with the device.


texts: Laptop chargers that say 20V, are they for charging 5s?

texts:
I understand that 5s Li-ion should be charged at 21V (4.2*5) however the only laptop chargers I can find are 19V, 20V, and 24V. Each is relatively close to the value that should be used for 4s, 5s and 6s.

Is this what they are really?

And can I use a '20V' charger to charge 5s Li-ion?


texts:
How does one go about calculating the current rating of self produced busbars?
Store bought wires are a lot easier, as they have the derating factors for parallel wires and ambient temperature readily available (e.g. Radox: http://www.beichang.cn/pdf/RADOX%20CURRENT%20CARRYING%20CAPACITY.pdf)
Do the manufacturers just come to these conclusions through testing?
I know there are a lot of factors playing into this, but am just looking for a ballpark estimate. This link is useful, but is for wires and not busbars. Will there be a meaningful difference?
My copper busbars have a cross section of 9mm2, and are exposed to good air flow. I am also interested in short time current burst ratings. Any advice/sources would be great, thank you!


texts:
Hi I want to use my (YHDC TV19) voltage transformer to measure 230 V ac supply using ADC, please help me with the value of current limiting resistor and burden resistor. (provide me complete schematic)

simulate this circuit – Schematic created using CircuitLab


texts: Charging board for 3 battery 3.6V used for supply an Arduino board

texts:
I would like to build an autonomous system that contains:
- An Arduino board (later, it will be just the chip)
- A LED strip

I decided to use 3x3.6V lithium batteries in series. So, the idea is to have the 3 batteries in series that supply the Ardiuno board and the LED strip in parallel.

Now, my problem is the charging the batteries.

After research online, I see that the best solution would be to charge them in parallel. There are many dedicated charging circuits on eBay or aliexpress for charging at 4.2V, is that good ?
To be able to have a good charging time, I need a output current of 2 or 3A, right ?

If this solution is good, when a will plug the 5V input and charge batteries, there is no risk for LED strip and ardiuno board ?

Or I will have to open the circuit when I plug my supply ?

When I will plug my supply, it will apply 4.2V on each battery. So, in series, I will have 3 x 4.2 = 12.6V. So, I need to check if LED strip and arduino if ok with that voltage, right ?

For arudino, it should be ok, for LED strip, I'm not sure, the normal voltage is 12V.

Thanks for your help,


texts: multi-cycle risc-v ZERO control line for branch

texts:
I have been having trouble to understand how exactly the execute stage in risc-v processor for branch works. what I understood is that the ZERO output from ALU calculations for branch produces zero and through combinational logic affect the PC register (does it output zero? and if so, then how does the and gate in the picture below produces '1'?)

I would appreciate it if someone could explain to me how do the combinational path is calculated from the alu to the pc register when there's branch. that's the path I'm talking about: Just can't understand what signals should be produced...

thank you very much!


texts: When it comes down to having PCBs produced is solder paste applied to the pads so I can stick the IC's down or do I have to add paste myself?


texts: AVR AtTiny84 is stuck on 128kHz clock, avrdude + Arduino as ISP can't reach it

texts:
While experimenting with the power consumption of different clock rates by setting fuse bits, I seem to have irreversibly programmed an ATTiny84 chip to the 128kHz internal oscillator, and now avrdude can no longer establish SPI communication with the chip.

I've been using an Arduino Duemilanove to program the chip, with the "ArduinoISP" sketch.

Some avrdude command lines I've been using, if they help - my vain attempts to get it back to 1MHz:

avrdude -p t84 -C "C:\Program Files (x86)\arduino-1.0.4\hardware\tools\avr\etc\avrdude.conf"
    -c stk500v1 -P COM7 -b 19200 -U lfuse:w:0x62:m -u

avrdude -p t84 -C "C:\Program Files (x86)\arduino-1.0.4\hardware\tools\avr\etc\avrdude.conf"
    -c stk500v1 -P COM7 -b 19200 -U lfuse:w:0x62:m -u -B833 -i833

I've tried a lot of different delays in the -B and -i settings, ranging from 1 us to 10000 us. Output is:

avrdude: please define PAGEL and BS2 signals in the configuration file for part
ATtiny84
avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.07s

avrdude: Device signature = 0x000000
avrdude: Yikes!  Invalid device signature.
     Double check connections and try again, or use -F to override
     this check.

avrdude done.  Thank you.

Adding the -F option doesn't help - it tries to program, but the fuse setting doesn't take.

Have I lost this $2.50 chip forever? :)


texts: How do different metal detector frequencies help to locate items like gold in the ground?

texts:
Metal detecting enthusiast here!

How does a change in frequency help to detect gold better?  I keep reading that one manufacturer's metal detector works at 18KHz to better detect gold.  Yet another manufacturer is about to release a new coil that operates at 15KHz, 30KHz, and 55KHz which will locate gold even more effectively.  Why does an increase in frequency help to locate gold with a metal detector?

Can someone explain that?

Here is a link to the coils in question.

http://md-hunter.com/new-xp-22-5-hf-coil-two-of-them-for-xp-deus-novelty-2016/

Link to the manufacturer's website and page that talk about their new coils:
http://www.xpmetaldetectors.com/blog-detection/en/update-deus/deus-product-information-and-news/


texts: How to calculate or should I measure impedance for 1/4 Wave monopole?

texts:
I have this odd design that I'm trying to improve the antenna on.  It has a mother board and a radio board above it, and it's densely packed with components.  My idea was to try a monopole in the middle of the board and bring a feed line over to it with some tiny coax.   What I don't know is how do I figure out the impedance of this setup so I can adjust the matching network.  Do I measure it with a VSA at my frequency of interest (900MHz)?

I assume the impedance comes from how well it couples to the various surrounding GND planes and that it would change based on where I position the antenna.  How far above the plane for instance.

I'm also thinking this would be hard to accurately simulate ahead of time with all the different components involved.


texts: Do I need to use a capacitor to smooth voltage when powering a microcontroller with USB?

texts:
I'm trying to make a CNC machine with an Arduino Uno and 3 stepper motors. I plan on powering the Arduino with USB, but I need a 5v power supply for the 3 stepper motor microcontrollers. I couldn't find a 5v wall adaptor at any nearby store, and was hoping a USB could suffice as I don't want to wait for shipping.

Researching online it seems that there may be voltage spikes that could possibly damage the microcontrollers when powered via usb. Is this something I need to worry about? Do I really need to use a capacitor? This is my first electrical engineering project, so I apologize if this is common knowledge.

Hopefully this diagram clarifies how I'm assembling this machine:

The power would be coming from the far right (red is power, black is ground).

The specific drivers I am using are the easy stepper motor drivers, and the specs can be found here:
https://learn.sparkfun.com/tutorials/easy-driver-hook-up-guide

But it is indicated that it works in a 5v system.


texts:
So here is the problem:

First, I have a door opener device that gives me one wire to control it. This wire should connect to ground so the device works. We do not want to make the door opener to work all the time, obviously.

Second, I have a device for remote control, when a button is pressed on the remote, a ground signal is output on the box for a couple of seconds. This is the only output of the controller and unfortunately It can't serve as a ground to the door opener. It has simply too much impedance to make the door opener work. It works with lighter loads such as leds. Unfortunately I cannot change this control I'm treating it as a "black box".

What I need help with is figuring out a way to use the controller wire as a "trigger" to activate the door opener.

Summing up:

Both devices use a 12v power supply
Door opener wire (should connect to ground)
Controller wire (ground signal)

simulate this circuit – Schematic created using CircuitLab


texts:
In given figure if we assume both sides (up and down) with equal number of coil  turns (N each).
And we wound(which generally we do in DC motor) coils such that they create flux and form a North-South pole as shown in figure .
What would happen to flux  if we wound 2N turns on upper limb (S pole)and its orientation is exactly similar to previous one but we  remove the winding from down side limb completely and then excite upper winding  by same source as previous
1.will flux  will remain same   that linked with rotor ?
2.what is problem in this type of winding arrangement although we are using same number of turns?


texts: Noise signal passed thru Normal ( Gaussian Random variable) distribution system : exam problem?

texts:
I know that Fx(x)= F((x+a)/o)

I don't know how to find Fx(x) that satisfy the p(y>=0)
can someone clear this point to me?


texts: Found this circuit inside a surge protector. Both the 910 ohm resistor and the fuse is tie right next to each other, and covered under a flame-resistant hoodie.


texts: Read voltage / tap into existing voltage divider circuit without affecting?

texts:
I'd like to unobtrusively read the voltage of a simple thermistor & voltage divider circuit. This is a hot tub/spa controller and it is using 5v -> 20k (R1) -> thermistor (R2) -> ground circuit. I put my multimeter on it which reads fine, but when I connect an esp8266 dev board ADC to this circuit (320k ohm) I am greatly affecting the resistance of the thermistor/R2 and messing up the spa controller temp reading.
Would I be able to get away with a megaohm level voltage divider for my ADC? I have a feeling it wouldn't work though so I haven't tried it yet. Also read a bit about buffers / voltage followers but I'm not sure if that's really as simple as adding one of those inline before my ESP's ADC?
I'm looking for a "good enough" approach. It doesn't have to be perfect, just better than what I have now (which is changing the thermistor resistance by kilo-ohms).


texts: Advice for 90 Ohm traces of a USB 2.0 HUB

texts:
I am designing a USB-hub that has many USB traces. I followed some guidelines online and read forums. Based on my understanding of a 4-layer stack-up, one of the best set-up I chose is 8 mil trace space and 10 mil trace thickness. I made the layer under the Top Layer as the ground plan. Is it ideal?

My main question is: Should/could I have polygon pour on the top layer (the same layer is differential pairs)? I searched a lot and did not find any note about the impact of polygon on the impedance.

This image is an example of a connection:


texts: Radio Waves propagation (Intuitive Understanding of Wave propagation)

texts:
I have few similar questions regarding Radio waves communication particularly FM and AM type of Radio wave communication. Please bear with the naivety of the questions.
Questions:
Radio waves in FM and AM communications are transmitted through Air and we pick those signals with the help of our receivers.
Assume few FM Radio stations such as 91.1MHz, 93.5MHz and 94.3MHz. (Area size radius - 10-15km)
All these stations are operating simultaneously and depending on what frequency I tune receiver, that radio station is played. But the idea is that all the above 3 radio stations are working and operating simultaneously.
Since the radio waves are EM waves, they propagate in air in the form of waves. So, technically, do these EM Waves propagate through the atmosphere by disturbing the air particles, I mean like, compression and rarefaction? I just want to understand how does these waves move from the transmitter to the receiver.
Question 1 : Do the EM waves travel by creating disturbances in the air particles such as compression and rarefaction?
If they travel like that, won't the compression and rarefaction pattern of the 91.1MHz radio station affect the compression and rarefaction pattern of the 93.5MHz radio station and cause any disturbance/interference/cross-talk between each other before they even reach my receiver? How won't those 2 radio stations interfere between each other ?
Question 2 : What would be typical distance range in terms of radius (in km) of an FM/AM radio station? I tried to find. But unable to find it. Somewhere, I have read that the distance coverage is dependent upon the power of the FM Radio Transmitter? Could someone please throw some more information like a certain table which would provided the distance covered and the radius of coverage of the FM Radio?
Question 3 : If the FM Radio communication are a type of line of sight communication, how am I able to receive the FM Signal even if my receiver is not in direct line of sight of the FM Transmitter?
P.S. The reason why I didn't make it as 3 separate questions because all these questions are very closely related so that I didn't want to burden the answer-er to the question or a similar fellow person who is having the same queries to find the answer under a single question itself.


texts:
Im running a few simulations with an energy harvesting project using Peltier devices as a Thermo-Electric Generator with PSPICE for TI. The chip powering the boost device doesnt have a pspice model and I don't have all the data handy (or able to be produced yet for that matter) to generate a complete behavioral model.
Are there any general rules for a fixed output voltage boost converter? I was thinking of using a voltage dependent current source since that is really what varies dependent on the input and load but I'm not sure how to use that while still having a steady 5V as output.
In summation, is it possible simulate (for given input range) a dc-dc boost converter(fixed output) with a combination of (voltage or current) regulated (voltage or current) sources with "reasonable" accuracy? Quotes because thats purposely ambiguous
Ckt specifics if it matters:
TEGs will be arranged to produce a minimum of 500mV and about 300mA
Boost module is Pololu U1V11F5 which uses the TPS61202


texts:
This MOSFET is from a good board for an RC plane. On a bad board, the MOSFET is completely fried and the number is not visible. The MOSFET drives a motor, and the motor stalled during a crash repair, which caused the MOSFET to pop, as well as damaging a diode (probably the catch/flywheel diode as it is across the motor.) In future, I will add a fast blow ~10A fuse to the motor line to protect the MOSFET.

I can replace the diode with any fast Schottky but I need to know the ratings of the MOSFET and I cannot find a datasheet anywhere. I suspect the pin out is gate, drain, source from left to right, but I cannot be certain. I'm not even sure if it is actually a MOSFET; for all I know, it could be a power NPN transistor. It has no heatsink on it (likely what caused it to fry when the motor stalled) and looks like a TO263 package. The numbers on it are "U438" and "BA8112".


texts: Low parts count and cheap radio modulation (hack)

texts:
I have an embedded electronics project in mind, but will use a different example to explain what I wonder.

Say we have to PCs, each with a sound card which can sample up to 44kHz. How do I get those to talk to each other over radio?  It helps if the antenna need not be huge, but low parts count and low price is most important. Can the audio signal be modulated in some simple way? Are there ICs which already does the major part?

I have a decent understanding of digital logic, but when it comes to analog things I need a lot of advice.

Assume the PCs can do a certain amount of processing of the signal. The sound card is stereo, could that be used for something?  Like use the left channel for data, and the right channel for some kind of modulation shift?


texts: Why would a battery BMS refuse to function after cutting off the wires and reconnecting them?

texts:
I tried to rebuild my laptop (Dell Inspiron 5537) battery pack with new Li-Ion cells so I removed the case, disconnected the cell wires and connected those wires to the new cells. After this point, BMS stopped working.

Is there any well intention for programming a BMS like so? One possible explanation I can think of is that if BMS thinks the voltage of the cells goes below the critical point for a Li-Ion (2V per cell), the recharging process may not be handled safely so it locks itself out to prevent any damage. Might that be the case? If so, shouldn't it unlock itself when it sees the appropriate voltage between the terminals?


texts:
I've created a footprint for the rotary encoder, which symbol is shown below

A footprint for this element has been done by myself.

I've been getting a warning which goes like this:

"WARNING(ORCAP-2435): Number of pins in footprint 'PEC11L-4XXXF-SXXXX' and instance 'EN1' does not match."

How can I get rid of that error?


texts: What is the pad size required for this BGA AW H3 Chip?

texts:
I'm trying to figure out the pad size to use for my footprint according to this datasheet.The last page in the datasheet has the package dimensions. I've also posted the relevant information in a picture below.

The bottom right has the dimension for the pad size but I cant figure out the actual measurement from the table it provides. I'm confused by the labeling, do I use eee or fff? and what is the purpose of C A B symbols next to eee and C next to fff.


texts:
While I was checking the ST L298 H-bridge datasheet, I read that the voltage sensing of it is -1 to 2.3 V.

Can you please explain what is the meaning of sensing voltage?


texts:
For my latest product, I have designed a USB ESP8266 dev kit for hobbyists (http://rxtx.weebly.com). The theory is that it fits into a USB-A plug directly through the PCB - hence why I am gold plating the traces.

But I noticed in several other posts that the PCB needs to be at least 2.0mm thick, but PCB houses charge a lot for that thickness - thus why I am sticking to 1.6mm. To compensate for this 0.4mm thickness, what kind of shim would I need - I only need it to cover an area of 10mm by 8mm and it won't be in contact with any rails - plastic, but which kind? Where could I source it cheaply?

The PCB material is FR-4 (ShengYi Tg140). Also, can you advise me on what glue type to use as I am new to adhesives?

Thanks in advance!


texts: n Gate to source capacitor in gate drive?

texts:
I'm designing a gate drive and I saw in a reference design this circuit,
what would be the explanation for placing a capacitor between gate-source of the MOSFET (or IGBT)?
I've read that a resistor is also placed likewise to prevent sudden turn ons?
*Also though it says it's not mounted, I'm thinking there was a reason for placing it.

I did some test with:

No capacitor
1nF capacitor
10nF capacitor

I added an idea of the schematic of what I'm testing, I'm using SiC MOSFETS, the power stage are two boost converters with common ground.

The driver ground is connected to the power ground of course.

This is what I found:

simulate this circuit – Schematic created using CircuitLab

]4

I think it is highly related to the comments of  Marcus Müller and the answer of JonRB.

Further explanation of this is appreciated.

Thanks


texts:
I have custom board utilising an LPC 1778 and I'm having issues entering ISP mode, or at least I think I am.
I am using the ISP pin and the reset in to enter ISP mode. By holding the ISP pin low and pressing reset, the device should enter ISP mode. I have it connected through a serial to UART device and when I send characters to the device it responds by echoing whatever is sent. It does this seemingly regardless of what I do.
Is there any way to verify what mode the device is in? I have tried using FlashMagic to flash the Bootloader but I get the auto baud error that seems to encompass a large number of things and doesn't inform me of what mode I might be in.


texts: What does ring and cylinder symbol mean?

texts: I'm seeing an odd symbol in a schematic provided in a datasheet for the power management chip ADP5091: a ring that goes through a cylinder. The cylinder is connected to the inductor (SW pin) and the ring is connected to the low side transistor of the boost converter. I've tried googling this symbol but unfortunately I can't find anything. Could someone please help me out with this? Thanks in advance!


texts: Wiring diagram - what is the meaning of stacked arrows?

texts: I'm trying to figure out whether the stacked arrows means the conductors are twisted together?


texts: Mini HDMI female - is one pin supposed to be shorter?

texts: I have a Raspberry Pi Zero with Mini HDMI output. I acts kinda weirdly - it does work with a TV with HDMI input, but when plugged into a monitor with DVI input (with an appropriate HDMI>DVI cable) it makes the monitor turn off (yes, you're reading that right - Pi is still running, but the monitor turns off and can't be turned back on until I unplug the Pi, as if it was shorting something). I noticed that one of the pins in the female HDMI connector of the Pi is shorter than others - 18th, to be specific. Is it supposed to be that way, or do I have a defective unit? I wasn't able to find any high resolution image of the connector to be able to determine that by myself, so I would appreciate some help.


texts:
The connector blows its solder when inserting the cable. It is SMD type.
Can I back it up with a special glue? What do you recommend?

I saw red little balls on a Xilinx board are these glue?


texts: Stiffeners needed under DFN parts in flex PCB?

texts:
This is the first time I'm designing flex PCB and I wonder do I need to put "stiffeners" under DFN parts which are soldered on flex PCB? Stiffeners would be on opposite side of flex PCB than DFN parts.
Flex cable is 4mm wide and 200mm long and has 3pcs of 2.5mm x 2.5mm DFN parts.
This is a prototype run and DFN parts will be hand assembled.
Design rules seem to propose using stiffeners but I would like to design the flex cable without stiffeners if possible.


texts:
In case of DC motor even if DC voltage is applied, due to commutator an AC current flows through armature ,then due to this changing current, does any voltage is induced across the field winding?
Thanks in advance


texts:
I'm designing a very simple multimeter circuit of which the ADC is that of an Arduino Due. Could you have a look at the circuit and tell me what could go wrong, what could be improved etc.?

Requirements

Voltmeter mode: ranges 30V, 10V, 3V, 1V OR +/-15V, +/-5V, +/-1.5V, +/-0.5V; bandwidth >= 300kHz
Ammeter mode: ranges 5A, 1A, 0.2A OR +/-2.5A, +/-0.5A, +/-0.1A; bandwidth >= 100kHz
Ohmmeter mode: ranges 1k, 10k, 100k, 1M

The accuracy required is 1% of selected range in all modes.

Circuit

CircuitLab editable:

simulate this circuit – Schematic created using CircuitLab

Full res picture:

The circuit is illustrated in voltmeter mode on the 10V range, here is the jumper position map for the 3 modes, the ranges, and the +/- switch. Each cell is a 2 pin header (except the +/- switch which is a 3 pin header) and contains the reference of the corresponding switch on the schematic. Physically, there is a 2x2 pin jumper, and a 2 pin jumper moved left or right, and a 2 pin jumper moved up or down.

The reason for the > 3V range is that the instrumentation amplifier does not allow gains lower than unity, therefore there is a divide by 10 stage with 10M input impedance inserted before the amplifier. The amplifier is internally protected up to +/-40V. Note that selecting a +/- range halves the range.


texts:
What would this big stainless plate be? Do they go bad?
This is a GPS by the way, and some buzzing noise coming from it. When I hold with my finger it quiets down.


texts: Trying to identify a component in a 12 volt LED on/off touch switch

texts:
I'm wondering if anyone can help me identify what this 8 pin IC is, in a capacitive on/off touch switch I have.  It is a soic or 8-VSSOP package.  64RX-Y is written on the bottom of the IC, nothing on top.  I can't find anything if I google that.  Pin 3 is connected to the touch input, pin 5 is connected to +5 volts from a regulator, pin 8 is connected to the gate on an N channel mosfet, and pin 6 is connected to ground.  I've searched for led drivers and flip flop ICs, but nothing seems to match this pinout.
I want to recreate this circuit because it works really well when connected to a steel lamp body that is powder coated, and turns the 12 volt LEDs on and off nicely.  I need to make a circuit board that is narrower and longer than this one though, so it'll fit in my lamp.
Attached is a schematic/layout diagram.  The mystery IC is in red.  Any help would be appreciated.


texts: How to correctly configure deepsleep for STM32L0xx

texts:
I'm trying to configure my Nucleo Board with a STM32L073RZ in deepsleep mode to get the lowest power consumption.
To do that I use the mbed librairies with the deepsleep() function (This function use Stop mode with RTC). On the application note given by STMicroelectronics the consumption is around 1µA in Stop mode with RTC but on my board I have 4,2µA.
This is my script

int main()
{
    User_Setup();

    RTCHandle.Instance = RTC;

    //Create and launch the RTC date (08:30:00 08/12/16)
    RTC_DATE_TIME(0x16, RTC_MONTH_FEBRUARY, 0x8, RTC_WEEKDAY_TUESDAY, 0x9, 0x50, 0x00, RTC_HOURFORMAT12_AM);

    RTC_AlarmConfig();

    while(1)
    {
        deepsleep();
        //Display the time after a wakeup
        RTC_TimeShow();
        wait(1);
    }
}

How can I correctly configure my STM32 to get the lowest consumption ?

Thank you for your attention

Simon NOWAK


texts: What is the speed of hard disk actuator arm?

texts:
There is a lot of material discussing the rotational speed of the magnetic disk in HDD but not about the rotational speed of actuator arm.

What are the typical actuation speeds of the actuator in HDD?

This information will be used in the design of a fast shutter system made by salvaging the HDDD actuator arm.


texts: BJT collector-emitter saturation voltage vs temperature

texts:
I'm using a BJT as a switch, so it will either be off or saturated.

I'd like to know how the collector-emitter voltage (when saturated) varies with temperature in general, (but perhaps take the BC179 for example - the datasheet only shows how it varies with collector current.)

Thanks


texts:
I'm sitting here with my Raspberry PI and some other equipment that requires digital signal (high/low, enabled/disabled).

But the Pi only has a GPIO so to get it to work I would need a microchip of some sort (guessing)?

I'm fairly new to all this, but like to play around on my breadboard.

Could anyone point me in the right direction here? I need the PI to control a device that operates with digital high/low signal but also "enabled" / "disabled"


texts: Disconnectors Symbol in Single Line Diagrams (SLD)

texts:
where should the moving part of a disconnector be located when breaking gets applied, on the energized side or on the disconnected side?
Is there any standard??
Suppose a non ring, simple grid and mention the authenticated sources for as much as possible please.


texts: Are these component values and functions proper for this device given its datasheet?

texts:
Im planning to use thisH11L1M-Opto IC with the following circuit:

Vin is around 5V 20Hz pulse coming after a LP filter to the opto device as shown above.
The specs says 1.6mA is enough for turn ON so I set it to 2mA. So for that I set the R1 to 1.8k since the voltage drop at 2mA is 1.1V then R1=(5-1.1)/2 = 1.8k. I added R2 for a floating input as 100k. Vo will drive a logic input.

If the values for R1 and R2 are reasonable, I have two questions:

1) Vcc is 5V; so what should be the resistor value for R3 which is an open collector resistor? I chose it 100k, can it be any value that Vcc can handle? I cannot see any recommendation in the datasheet.

2) Do I need a decoupling capacitor C1 like 100nF between Vcc and GND like in an opamp?


texts: A question about a Class E Tesla Coil circuit

texts:
The link to the original website and the schematics :

http://uzzors2k.4hv.org/index.php?page=4MHzclassE1
http://uzzors2k.4hv.org/projectfiles/4MHzclassE1/proper_4MHz_classE_SSTC.gif

I'm trying to build a 2n3904/2n3906 mosfet driver based on the same design, but at 13.5MHz,
but am having some problems.

Here are my questions :

I understand the purpose of the 9:4 transformer to be that of impedance matching, however I cannot find any reference on how to calculate the output impedance of the 2n390x push-pull output stage. Judging from the circuit it looks like it's about 200Ohms, but how is this value calculated?
The bottom part of the schematic uses 2 2n3904 BJTs. I'm guessing it's a cascode configuration, but that's not the usual arrangement found in the cascode circuits. What exactly is it?
Is there any hope I can make this work on my 13.5MHz driver driving IRF740 with C_iss=1400pF?


texts: I am interested in a LiFePO4 Lithium Iron Phosphate battery product and wonder if anyone knows what type of terminal connector the battery has. Thanks in advance!


texts: Driving a 24VAC solenoid with arduino using a octocopuler and a triac

texts:
Following a previous question I have redesigned my schematic:

I'm trying to energize a solenoid used to open and close a 24VAC sprinkler valve

I have the following questions :

1) The GPIO leg can supply up to 500mA, is it enough to drive the optocoupler or should I use a transistor to activate it?

2) I have based my design on others I found on the internet like this one:

But, what are R3 and R5 (R19 and R20 in my case) used for and how should I calculate the proper values for them?

3) I'm using a TVS bidirectional Diode for EMI suppression for inductive AC loads, should I use snubber circuit or with the diode is enough?


texts: electrical fridge running on car battery

texts: I'll be out of grid for some days and I'm planning to have a small electrical fridge with me. It's a 12V 4A small fridge with a cigar lighter plug, but I won't have a car with me, so I think I could connect it to a 12V car battery? My questions are, does my plan make any sense? Also what do I need to know so I can figure out how long the fridge can run before the battery runs out?


texts: Reduced output of op amp peak detection and hold circuit

texts:
I have used op amp peak detector & hold circuit for finding the peak of voltage obtained from scintillation detector and pre-amplifier.

I observed that the observed peak and hold output was 700 mV, instead of the expected 1.5V and that when the pre-amplifier was connected to the peak and hold circuit, the portion of the pre-amplifier output waveform above 700mV was clipped. For debugging the issue, the following points were checked:

The Op-Amp circuit is not loading the source by drawing excess current.
Op-Amp slew rate is 125 V/us and that the rate of charging the capacitor with 1uF cap and 100 mA short circuit current is 100 V/us. The detector pulse rises from 0 to 1.5V in 100 ns, so rate required is 15V/us
A 20kHz triangular wave with 1.7V was provided to the peak-hold circuit. The peak-hold output was 1V and the input triangular wave was clipped to 1V pk-pk. SPICE simulations show similar, but less severe results. The effect is least if the input is a square wave or the frequency is least.
The circuit works for DC input (provide 3.3V and disconnect it, the capacitor voltage started falling from 3.3V)

All the above observations have been done with nMOSFET in open-state.

Can any one tell me where am I going wrong in the design?


texts:
I have a 6 volts DC motor and want to control it with stm32 and change the rotation direction.
Previously, I designed an H-bridge, I used for the upper part IRF9630 and the lower part IRF630,I connected the HIGH part to 12V and the motor didn't work and even move.
After that I changed MOSFETs and used IRF4905 and IRFz44n.But it didn't work again.
Can anyone tell with the output voltage of 3.3v micro stm, IRFz44n can be fully on ?and what resistors should be used for gate and source?

This is what i have been made...


texts: Why are the capacitors set up this way in this old tube radio?

texts:
I'm trying to figure out what's going on with these capacitors, so I can replace them in an old tube radio, but why are they connected in this way?

simulate this circuit – Schematic created using CircuitLab


texts: Replacing glass fuse with reset button fuse?

texts:
Several months ago i made a 10Amper power supply with 5 outputs, each output has a fuse holder for crystal 10A Fuses, they work as intended but its a chore to replace them every time i short them, i found this "10A reseteable fuse" however what are the chances of this relacing the glass fuses with no drawbacks at all?,

I do know poly fuses take a while to act since they blow by the heat generated by the short circuit, putting at risk the load, however, im not quite sure what kind of fuses are these in the picture could they work out better than poly fuses? what kind of fuses are inside these devices?


texts: Do data centers use single phase or 3 phase to power their infrastructure?

texts: 3 phase is more efficient than single phase for converting AC to DC; since after rectification stage the signal requires less regulation. Do some data centers use 3 phase power to take advantage of this efficiency? If so, are the energy savings significant? Are the servers fitted with specialized PSUs to utilize the power?


texts: Charge a Lipo with only Constant-Current Stage?

texts:
I'm following this standard algorithm:
http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries
Algorithm for charging LI-PO batteries?

but am wondering if I can get ~80% of the capacity with just the constant-current stage, why not just do that?  Is there something about the constant-voltage stage that is helpful for the chemistry (knocking off dendrites and such?).


texts: How to use Op-Amps as comparator in high frequencies?

texts:
An Op-Amp wired as a comparator can change many wave form (including sine wave ) into square wave but I asked about correct feedback resistor and input resistor values of an op-amp here and we came to the conclusion that these values should be small to avoid capacitance effects.

In an Op-Amp in comparator design, the feedback resistor is around tens of mega ohms and this causes many parasitic effects as well as low pass filter effect that diminishes the output.

In practice, I used AD826 as a comparator and I can see it makes a clean square wave in frequencies less than 1MHz but distortions start in higher frequencies until the output is nothing except a background noise in 5MHz.

What is the best design for an Op-Amp as a comparator in higher frequencies? I am using this simple design (pin numbers are not related to AD826):


texts: How would I limit speed of dc motor being used as a generator?

texts:
How would I limit speed of a DC motor being used as a generator?
For a project where I have to make a wind turbine that will automatically limit speed of rotation once past a certain value.
Thanks :)


texts:
1.I have been using oscillator circuit as Parametric delay block with the
   help of other sub blocks at the output/around.

Second method is RC for the delay at the output of any circuit (ABM) or
comparator
-Example Netlist

.SUBCKT COMPARATOR IN+ IN- OUT PARAMS: DELAY=1n
E_1 OUT_int 0 VALUE= {IF(V(IN+) > V(IN-), 5, 0)}
R_1 OUT_int OUT 1
C_1 OUT 0 {DELAY /(0.693)}
.ENDS COMPARATOR

But the second method does not provide accurate delay and it gives exponential behaviour.

Is there any better way of implementing Parametric delay circuit in modeling point of in PSpice/ltspice?


texts: What is the purpose of EEPROM in the PCIe accelerator card?

texts:
As i am exploring the many PCIe accelerator card features and design aspects, in few design I could find the Block called as 'MAC ID PROM'. And in the design they have provided the EEPROM circuit.
In A10PL4 FPGA acclerator card it explains that PROM provide access to boards MAC ID, please let me know what does this MAC ID means in PCIe card?
Someone please brief me the actual requirement of EEPROM in the PCIe accelerator card.
Note: attached the block diagram of few accelerator card
Regards
Balkis


texts: DC motor parameter identification using microcontroller

texts:
I've built a DC motor controller which measures the speed and current (not really sure yet about current values) of a permanent magnet DC motor. I plan to connect different PM DC motors. Is there a way to build a software routine which identify the motor's characteristics and adjust the parameters of the controller (let's say a PID) according to what is best for that specific motor? When there's enough load, the motor tends to decrease the speed and that's what I want to compensate.

Is it strictly necessary to use MATLAB to identify every motor I plan to connect? I don't have much experience designing PID controllers microcontroller-based. I would appreciate any suggestions.


texts: How to calculate the required base resistor for this BJT-relay circuit?

texts:
I'm trying to design a relay circuit for my first PCB and have come up with the following:

The 10K value for R7 is just a placeholder. R7 is what I'm trying
to determine.
The transistor should turn the relay on and off based on whether D2
is at 5V or GND.
The relay is a 5V relay and has a coil resistance of 63 Ohms, so the
coil current is 79.4mA.

How do I determine what value the base resistor (R7) should have for the circuit to work?

Datasheets:
Relay,
Diode,
Transistor

My attempt:

Ic = 80mA (relay current) + [5V-Vce]/10K (current through LED)
Ic = 80mA (relay current) + [5V-0.5]/10K (current through LED)
Ic = 80mA + 0.45mA = 80.45mA

Ic = hFE*Ib
Ib = Ic/hFE
Ib = 80.45mA/120 = 670uA

Ib = [5V (D2 high voltage) - 1.2V (base-emitter saturation voltage from datasheet)] / R7
R7 = [5V-1.2V]/Ib
R7 = 3.8V/670uA
R7 = 5672 Ohms

So, according to my calculations, the base resistor should be ~5.6 kOhms. However, I have no idea whether did this correctly or not.


texts: Estimating the adequate ADC resolution given a sensor resolution

texts:
A force traducer has a resolution of 0.0625N. And the analog output sensitivity is 32N/V. So I calculate the voltage output resolution as 0.0625/32 which is around 2mV.

If this signal now is sampled by an ADC with an effective resolution of 0.5mV or 4mV what would be the benefits or disadvantages? What would be the advantage of going better ADC resolution or disadvantage going lower ADC resolution?

(I'm neglecting any other external noise)


texts: Help identifying tantalum capacitor marked E105

texts: I am trying to repair a device that was handed to me. It has a broken tantalum capacitor with a missing lead, so it needs replacement. However I'm having trouble identifying its capacitance, voltage etc. I believe it's a KEMET T494 series but I can't say for sure. The markings on the capacitor are 'E105'. Does anyone have any ideas?


texts: A better programmer for PIC microcontroller?

texts:
I work with a project which uses PIC32 and PIC24 controllers.My setup has a Console board(PIC32) which communicates with 3 slave boards(PIC24) over RS485.

I have two projects -One for Console and other for 3 Slaves under development.

Currently i use a ICD3 to program them and it literally sucks with those irritating bugs while removing them and programming them.I don't know if the issue is the ICD3 cable or the ICD3 itself which is pretty new.I get errors like- Device id error,FPGA error, etc

I use MPLABX 2.0 IDE and don't have MPLAB8 to avoid another nag of Driver switch.

Is there any better and faster way to program when you have multiple boards and projects?
Can i add any interface with USB  for programming on on my board to avoid ICD3? Like Arduino? USB to USB on PC for faster change of board and programming?


texts: How this SMPSU start up and working on CC mode?

texts:
I want to understand how my switching power supply work and how to modify value for CC and CV mode.
The SMPSU I got is almost identical to this reverse engineer schematic. (link here)
I alo inserte the schematic image to confirm accessibillity.
The question is.

How this circuit start up? It needed voltage supply to controller ICs where it came from?
How the current control work in this design? It seem very different and more complicare than the circuit  from datasheet.

This circuit provided by tl494 datasheet

for datasheet circuit I can find CC mode set point by make both side of error amp equals. From inverting input it got 1V from voltage divider and non-negative side, it got 1V from 0.1R resistor which mean current must flow 10A at CC mode.


texts:
I am trying to build a simple ECG circuit. I designed the circuit based on multiple ideas from the internet and the parts (INA118P) available. What I do not exactly understand is how much the gain of the right leg drive should be. I marked on the schematic that gain=39 for DC, but I do not understand why this is the optimal gain value. What is a generic rule for ECG circuits? How does one determine a suitable gain for the right leg drive? Is it maybe a good idea to make R5 adjustable?

(Also I am curious whether the unmarked op-amp can be a simple LM324 or I need something more specific. I guess signals over 1kHz are not really important, but the feedback capacitors C2 and C4 are suspiciously small.)


texts: How to switch AC line on and off with a DC control wire

texts:
This might be a really simple rookie question.

I (who am very new to electronics) need to be able to switch a 24 VAC line on/off using a DC signal coming from an Arduino. Google searches have been fruitless (but then, I don't really know what to search for). If someone could point me in the right direction.


texts: jfet series switch isn't pulling the output to 0V

texts:
I gave a square wave [-10, 0] across gate-source and the input is dc 10V.
When the square wave is -10V, I thought the jfet cutsoff and the output would be 0V. But I'm getting ~3.1V at the output. Why is this so? Am I applying the gate control square wave correctly?

simulate this circuit – Schematic created using CircuitLab


texts: What does happen if the ratio of an ideal transformer is complex?

texts:
I have seen two solutions, both of then containing a paradox: Firstly, current and voltage ratio are inverse AND conjugate. In this first case, the two-port matrix is not symmetric (non-reciprocal). Secondly, current and voltage ratio are just inverse (no conjugate). In this second case, the power in the primary is not equal to that in the secondary; depending on the phase of the ratio, the transformer can have even gain or losses.
Which is the correct model? How can be explained non reciprocity in the first case or the difference of power in the second one? Does anybody know any published analytical study on this topic?


texts: Help me interpret this audio jack schematic

texts:
I'm having trouble interpreting the following schematic:

From this drawing: Adam Tech ASJ-99H-R-HT-T/R drawing
I want to know:

Are 5 and 6 normally open (open when there's no plug inserted), or normally closed?
Are 2 and 5 electrically isolated from one another or shorted together?

I don't have a sample on hand; the schematic should contain enough information to answer these questions.
If anyone can link to a resource that can explain the schematic symbols, that would be really helpful.


texts: Torque in a 3-phase delta connected induction motor

texts:
I know the equation for torque is

        T=[m*(N2/N1)^2/2*pi*Ns]*[s*E1^2*R2/R2^2+(s*X2)^2]

N2/N1 is the effecting rotor-stator turns ratio. I have it written like 0.90:1.

How would I write it as N2/N1? Would it be 1/0.90?


texts:
There is a monopole antenna with length of 141m.

So the antenna operates in 531kHz frequency. (lambda=c/freq, length of monopole antenna = lambda/4)

Let's say that I wrapped the antenna and make a N turns loop antenna.

(still operates in 531kHz)

Then, is this equation right?

2*pi* R *N=lambda/4 (R is radius of the loop)


texts: How do select capacitor for 400A surge currents?

texts:
I have a 220nF capacitor in a series with my surge protection circuit.

As can be seen from my spice simulation, the capacitor gets a surge of current passing through it under fault conditions, and ideally, I don't want the capacitor to explode. From looking at capacitor datasheets, surge current and power capacities of capacitors are unclear.

How do I go about selecting a capacitor for my application?

-------Requested additional information--------

For simplicity, I have cropped the schematic to show where the capacitor is located. The Surge comes from the primary of the transformer(left) which has some leakage attached (L4 & L5). The transformer is 1:1 and has two ohms series resistance.

When the surge comes through, the output TVS clamps through the capacitor.


texts: Getting IR signal from remote controller

texts:
I was trying to get a IR signal from a remote controller.
I hooked the IR receiver to the oscilloscope and I got nothing. Then i brought the remote controller very close (~1mm far of the receiver) I started getting signal, but it was random (with another controller that I have, if I hold one button, it first send the button code and then a constant value; this doesn't happen with the other controller).
I disassembled the controller, this is all the information I got:

XWDB-1106
LXZK-TX1021-v1.0
(cristal oscillator) NDR4208 [I think it ends with "i1", I'm not sure]

The receiver I'm using it's the VS1838B.

Maybe the controller frequency it's not the same as the receiver?
Edit: The remote controller was RF, not IR.


texts: Prove a theorem about an upper bound for entropy of a random vector

texts:
There is a theorem that:

if Z is any zero-mean, complex random vector with covariance \$E[ZZ^H]=R_z\$, then \$H(Z)\leq \log|{\pi eR_z}|\$, with equality holding if and only if Z has a circularly symmetric Gaussian distribution and \$H(Z)\$ is the entropy of Z.

I do not know what the name of this theorem to seek its proof in books or articles. I will be thankful if someone tell its name to me, or offers a proof for this theorem.


texts: Solar Panel not heating heat 30 AWG SS304 Wire

texts:
i try to make simple wire heating using solar panel.
Problem is the wire not heating at all.
I assembly solar cells 52mm*26mm in parallel 11.38 volt, amperage should be at least 2 or 3 amps.

Some experiments that i have tried using Solar Panel assembly as power source, 11.38v

775Motor: 0.09V, 0.11A, motor not running.

ToyMotor: 0.34V, 0.1A, motot not running.

SMD LED: 2.83V, 0.1A

Cree LED: 2.56V, 0.14A

Single 30AWG SS304: 0.74V, 0.1A, 7.1Ohm, not heating.

Multiple 30AWG SS304: 0.05V, 0.11A, 1,4Ohm, not heating.


texts: Determine the amp hour rating of a home made battery pack

texts:
I'm thinking of making my own electric bicycle, and I need help determining what the amp hour rating of my battery pack would be. I'm going for 36v and 8 or 9 amp hours.
So, with 10 batteries in series, I can get a single, low capacity pack with 36v. If I were to make three of these, and put those in parallel, I'd have three times the capacity. But, with each battery providing 2500mah, that's 75 amp hours, and I know that's not correct. What am I forgetting? image according to my knowledge and to the picture, series doubles the voltage and the capacity stays the same


texts: Make electronics - charles pratt - experiment 11

texts:
As explained in a previous post, I thought I could use a MOSFET as alternative to the PUT originally used in experiment 11 of "Make electronics" from Charles Pratt.

See original circuit below:

And my proposed alternative with MOSFET below:

As you can see, the original circuit is a slow speed oscillator, making the LED flicker. For obscure reasons, my proposed alternative doesn't work. Any idea how to make it work?


texts: What is the name and purpose of the following component?

texts:
I'm trying to repair a small electronic door bell.

I was wondering what is the name and purpose of the white box component ?
It seems to be just a wire with some white body around.

Is it a resistor or a fuse? My guess is that 4W22R means 4 watts  22 ohms but I'm not sure.

How can I test that component is still working ?

AFAIK the ground (the black wire) goes through the 400V capacitor first, then it has to go through that white component before going to the bridge rectifier.

EDIT : I found out the issue : the zener diode is dead and acts like a wire (it's always closed). Because of this, the main 400V capacitor is never charging and don't provide power to the rest of the circuit.
I disoldered the diode and tried to put 5.0V directly between the solder joints using a external power supply, it works again !
Thanks Marko Buršič for pointing out the zener diode.


texts: How are PWM IC's able to provide so many features in small footprints ?

texts:
If you look at the general pwm IC's for standard topologies (buck, boost  etch) , they have tons of protection features such UVLO, overvoltage, cycle-cycle protection and overcurrent protection.
They are able to provide all these features in a very small footprint.

Take for example the NCV3843 chip (as many other chips).
 https://www.onsemi.com/pub/Collateral/NCV3843BV-D.PDF

How are they able to provide all these functionality in such a small footprint?

and do they do this in a pure analog way or is there some a/d conversion happening first ?
 I would like to believe the latter.


texts:
I have a Autopilot PCB which runs a 12v dc hydraulic pump which has been running fine until now. When the pump is not attached the output from the PCB is 12v. When i connect the pump the output drops to 4v and the pump doesn't run. Ive tested the pump and it is working fine.

Ive tested the large capacitor and it seems fine. If someone could point me in the right direction as to where I should be looking I'd really appreciate it. Thanks

Only managed to find this diagram. I will keep looking.

Pump specs

The power supply is a large battery bank which is fed by a 75hp diesel engine.


texts: Disconnecting two batteries in parallel when motor turns on not working

texts:
I am trying to figure out why I can't get this circuit to work. I have two batteries that need to be normally connected in parallel when a starter motor is off, and when the MCU (Arduino) turns on Q4 transistor, I need the batteries to be isolated from each other to prevent the starter motor browning out the Arduino. I wanted to do this using solid state components and not a DPDT relay.

I thought that when Q4 goes high, it would pull the base of Q3 low which would therefore keep the gates of Q1 and Q2 high which would keep the batteries isolated from each other when the motor cranks over.

I'd appreciate any help. I tried the below circuit on a breadboard but can't grasp how to get what I want working.


texts: Understanding the guarding circuit in an instrumentation amplifier

texts:
I've got a project to make but I have trouble understanding what is actually going on. In circuit below, I have to calculate the resistor values, choose op-amps and explain how the whole thing works.

This is an in-amp for EMG and I can't understand how the guarding circuit (U1C, R1, R2) works. I saw a similar thing in the Art of Electronics, but the guarding circuit was referenced to the shield (which makes sense to me). However, here the op-amp output is connected to the gain setting resistors and I got from simulations that it improves CMRR, but I don't understand the principle of operation.

Also, why are R1 and R2 10kΩ, and not 10Ω or 10MΩ? How do I choose the tolerance? I have the same question for the other resistors. I just picked values from INA128 in-amp. From what I understand, we don't choose small resistor values in the differential amplifier, because the mismatch between them will affect CMRR more than with large value resistors, but large values are noisy and we should also provide enough biasing current, so we must choose between 10kΩ-100kΩ. In the input buffers we need large value resistors for the gain of 600-1000, but too large resistors create input error, are noisy, have parasitic capacitance etc, but I'm not sure if I'm correct.


texts:
I am studying about LDO and I came across this App Note

While reading, I encountered the following questions.

At the end of first paragraph, they mention "This is a closed-loop system
based around two main poles, the internal pole of the error
amplifier/pass transistor and the external pole of the output capacitor’s equivalent series resistance (ESR.)"

What do they mean when they say, "two main poles?" What does it mean in electrical terms?
"PSRR is usually specified at a specific frequency,
for example 60 dB rejection at 120 Hz." What do they mean by 60dB in terms of electrical voltage?


texts: calculate input resistance with known adc value

texts:
I am fairly new in the electronics world, but I would really like to learn it. The problem I'm facing right now, is that I miss the insight to be able to tackle this specific problem.

I have to calculate the input resistance of a system on the basis of a given ADC value. There will be an temperature sensor connected to the input, which will give some resistance, depending on the temperature. What I want to know / calculate, is the given resistance, so that I can calculate the right temperature. I know how to convert the ADC value to the correct voltage, but I do not know what the next steps are.

I calculate the voltage as follows: \$\text{Result}_{\text{mV}} = (\text{Reference}_{\text{mV}} / \text{BitSteps}) \times \text{ADC}\$

That gives the correct voltage at the input of the ADC.

Given the following diagram, which follow up steps should I take to calculate the input resistance?

74HC4052 Dual 4-channel analog multiplexer/demultiplexer data sheet

MCP6L04T/E/SL operational amplifier data sheet


texts: Pros and cons of supercapacitors in defibrillator

texts:
Basically I wonder about pros and cons of using super capacitors in defibrillator. It is known that 1.5 - 7 kV signal with duration from 1 to 200 ms is applied. The energy should not be more 200 J.
Also, some constraints like no ordinary batteries on board, low current source to charge capacitors (it's a 'natural' power source like microbial fuel cell, just about 0.2Amps@0.7Volts per cell).
Also I am not sure if the capacitors can be used to be  dishcarged into load or we have to do some transformations in circuit.
Thank you for any hints and clarification.


texts: What is the difference between magnetic and primary inductance?

texts:
I try to calculate ramp compensation resistor (Rcomp) for flyback SMPS converter design. For this, I examined slope compensation section at page 15 in NCP1252 datasheet by OnSemi.
But, there is a parameter which I don't understand. Calculations are below as screenshot:

Mixed point !!!
Ns/Np = 0,085
Lout = 27µH
Lmag = 13mH (?) WHY?
As I know, L2 = L1 x (N2/N1)^2
So, Lout = Lmag x (0,085)^2 = 27µH   --> Lmag must be 3,7mH
But, Lmag = 13mH in NCP1252 datasheet
Are magnetic and primary inductance different each other?


texts:
I'm planning on a home automation system, and two sub-sections will be separated by (say) 100 feet. These will be connected by a low-amp, low-voltage data connection. To avoid running significant power over that distance, I would like the "remote" sub-section to have its own supply, separate from the "primary" sub-section.

Each power supply might be a wall wart, or maybe an ATX supply.

The data connection will run at 3.3V or 5V (relative to ground/reference), and "should" only flow a few nA of current.

Can I safely run a ground wire alongside the data, and tie these two supplies together, to create a common reference for the data voltage? What is the potential for current flowing through that wire, looping through the house's AC main supply system?

I've done some reading, and haven't found an answer that directly matches up to this query about potential current flow over that ground connection. From that reading, it does appear that if I expand to multiple sub-sections, then I should connect the grounds in a "star" fashion, running each tie-in back to my primary.

TIA!


texts: Biasing the push-pull follower to eliminate distortion

texts: Could anyone please explain me the circuit? Especially the role of the 100 ohm resistor. In addition, which of the transistors conducts in positive and negative input? Thank you.


texts: Can ModelSim PE Student Edition co-simulate with MATLAB/Simulink?

texts:
I successfully simulated my Verilog code in ModelSim-Altera Starter Edition. I want to incorporate MATLAB/Simulink in my simulations. However, I failed. I have this error in ModelSim-Altera Starter Edition:

  Warning: ModelSim Altera edition is not supported by HDL Verifier
  In hdlsim>l_ParseVsimVersion (line 1081)
    In hdlsim/l_GetModelSimLibInfo (line 531)
    In hdlsim (line 123)
    In vsim (line 106)

It seems like the ModelSim-Altera Starter Edition is not compatible with MATLAB/Simulink. I downloaded ModelSim PE Student Edition and am wondering if it can do the cosimulations. If it cannot, do you guys have other ways to co-simulate without me getting the paid editions? TIA


texts: Designing an Embedded PI Controller for Speed Control

texts:
I will appreciate your guidance in this. I have some previous posts on this, but now I'm showing the code. I'm designing an embedded PI controller using a STM32 Nucleo board. In the PWM configuration, a 0 means 0% duty and 800 means 100% duty. The objetive is to regulate the speed of a PMDC motor. I'm confused about the PI output and the duty cycle relationship. This is what I have:

int error=0;
int target_RPM=0;
int duty_cycle=0;
int Kp = 0;
int integral = 0;
int current_RPM = 0;
int Ki = 0;

I plan to execute the following PID loop every 5 ms (not sure yet) with an interrupt.

//Get current RPM
current_RPM = read_RPM();

//Get the error
error = target_RPM - current_RPM;

//Calculate the integral
integral = integral+error;

//Calculate the Control Variable
duty_cycle = (Kp*error) + (Ki*integral);

//Limit the Control Variable to within 0-800
if(duty_cycle>800){
    duty_cycle = 800;
}
else if (duty_cycle<0){
    duty_cycle = 0;
}
htim1.Instance->CCR1 = duty_cycle;

I still don't have the PI constants. First, I want to make sure that the algorithm is correct. Also, I know I need anti-wind up for the integral variable, but still not sure how to implement it.