texts:
I was reading a most likely old article about, Adrian Thompsons work on using genetic programming to generate circuit solutions for simple tasks such as frequency differentiation.

This got me wondering,

Every gate in a circuit is just a collection of transistors, so could there be efficient transistor level optimizations, which may not really have any gate equivalents that can be detected by GP's or some other clever group of algorithms.

And getting really low level, transistors are just collections of blocks of doped semiconductors with wiring appropriately placed. If we had transistor level optimal designs, could they in principle be fast and efficient enough for us to explore the space of ways to stack different configurations of just wire and doped materials to get a job done, foregoing even transistors instead for rich complexes of various blocks of material interacting in, at this point very non trivial, ways?


texts: In my simulation of Van der Pol equation in matlab, I need to have variable factors the same as shown in following picture but Simulink doesn't accept that. how I can solve this problem?


texts: LTSpice: how to setup sinusoidal or exponential voltage source?

texts:
My textbook proposes to calculate power for the voltage source which has sinusoidal or exponential waveform. Probably my question is very silly, but I really don't know how to input textbook's equations using LTSpice independent voltage source setup menu:

v(t) = 10*sin(24t) + 14

and

v(t) = 12 + 15*exp(-200t)

What are DC offset, amplitude, frequency, Tdelay, Theta, Rise delay, Rise tau, etc? How to proceed if my volatge source has cosine (not sine) waveform?


texts: Reading 2D Arrays into a Microcontroller

texts:
I have a scenario where I have 2D arrays of variable sizes and various data types (double and boolean as of now). These arrays should be read and processed by a microcontroller which has 256KB of SRAM.

In my setup I plan to transfer these arrays from SD card (stored as files) to SRAM for processing. I currently can think of following possible aproaches

These arrays are actually matrices from MATLAB. So I intend to save MATLAB variables as .mat and reuse code from matimport.c
Save the data contained in the variables in an xml file. Use an XML parser for the target microcontroller
Create custom binary files with associated metadata. So the program in microcontroller reads the metadata(rows, columns, data type)about the binary file and extract variable based on offset's computed from the meta data

Sol 1 looks easy and straight forward. But, I guess I need to use certain MATLAB external libraries and I suppose these precompiled libraries (such as libmat.lib, libmx.lib) are not available for ARM.

Sol 2 is easy if there are good parser's written for a microcontroller. Suggestions of XML parser's are welcome

Sol 3 involves slightly more work. For this method, I intend to write a C application that reads .mat files and create a custom binary file with metadata and actual data. And have another identical import function in the microcontroller.

Total size of all variables combined is the range of 20KB to 40KB. Therefore, SD card is used in the system.

Which among these techniques is well suited for a low footprint embedded solution ? My goal is to choose and go with a solution that utilizes the least amount of memory and one which is most flexible for expansion. Ofcourse, do suggest any other approaches to solve this problem.

PS. The device is not Arduino based. But, I nevertheless added it as Arduino Development comes under the realm of this question.


texts: A question about practical use of ignition

texts:
As far as I understand, if I'm not wrong there is capacitor discharge ignition and inductive discharge ignition.

Is the difference between two in one of them the current spike is drawn from battery and the other from the capacitor? And which system is used in modern automobiles?

edit:


texts: When/How does the rotor stop accelerating in a motor?

texts:
I guess I get confused because things don't work like they would in an RL circuit. In that case the emf at first 'jumps' to match the source's voltage and decays over time reaching zero eventually.

When we have a motor though it's the opposite. Why is that? My guess is the induction of the emf is not 'directly' related to the current. It's caused by the change in ΔΦ which this time is caused by the rotor's movement and it's not created by the current. The current is definitely what causes the movement (Lorentz force) but I hope you get what I'm trying to say. Am I correct in my thinking? The motor accelerates and ΔΦ/Δt increases(I'm not sure but it has to so that the emf increases too) and at some point the latter becomes stable.

Does this mean that emf is still there opposing the source's voltage but now they are equal? I read somewhere that acceleration stops when the torque is the same as the load torque. I haven't exactly understood what the load is in the case of the motor. I also found that if you increase it, the rotor slows down even more.. but how? What is the load torque? I would really appreciate it if you could also clarify this part. Thank you.


texts: If I were to connect a bettery to the two sides of a container that contain only hydrogen gas, and its not dense (it's pressure is one atmosphere), what would it's resistance over the length of the container be?


texts: Representing Capacitors and Inductors with Initial Conditions for use in a Thévenin Equivalent Circuit

texts:
Recently I have undergone a project involving a Thermo-Electric Cooler (TEC). I successfully recreated the manufacturer's datasheet curves by simulating the TEC in LTSpice using thermal circuit modelling techniques. In doing so, I discovered a question that, while irrelevant, distracted me for hours.
Consider a big block of aluminum of some mass such that its thermal capacitance is 1000 (J/K). Imagine it is connected to a smaller block with thermal capacitance of 500 (J/K) through a thermal strap with thermal resistance of 0.1 (K/W). The thermal circuit equivalent is below (yes, GND should be zero Kelvin, but shush the end result is the same shifted by 273.15C in this case):

Now, here's where things get knocked into twelfth gear. I set the big block's initial temperature to 20C by doing a ctrl+rmb over the capacitor and typing "IC=20" in the "SpiceLine" field. In a similar fashion I set the small blocks temperature to 80C.
My question is: how does one find an equation (closed-form or otherwise) in the time domain AND the Laplace domain for currents (heat flows in this case) and voltages (temperatures in this case) in circuits in which Ls and Cs have initial conditions? That is, what are the lumped Laplace models for Ls and Cs with initial currents and voltages, respectively?
I also humbly request some intuition as to why these equations make sense!!
LTSpice has no problem telling me the system settles to around 40C, as seen in the figure above. To help me answer this conceptual question of modeling initial conditions, I looked for practice problems solving Thévenin Equivalent Circuits. I can find countless examples involving Ls and Cs in textbooks and on the internet. However, in EVERY SINGLE ONE they assume zero initial conditions!
I will attempt to answer this question below using Laplace expressions, however if someone could point me in the direction of a time-domain expression for two capacitors sharing charge, it would be much appreciated! I've been racking my brain at this for days.
Impedance of Capacitor C in Laplace domain--> 1/(sC)
Laplace model of Capacitor C with initial charge --> 1/(sC) + Vi/s (?)
Let's investigate using LTSpice by removing the initial voltage on the caps and instead placing a series step with each:

suspiciously similar results...
How about Inductors with some initial currents through them? For this we must leave the thermal stuff behind, because as far as I'm aware there are no thermal energy storage phenomena in life that lend themselves to inductors:
Impedance of Inductor L in Laplace domain--> sL
Laplace model of Inductor L with initial current --> sL || Ii/s (?)


texts: Possible methods to control the voltage of a variable 3 phase power supply for an electromagnet?

texts: The only solution I can think of is a three phase variable transformer, are there other methods? If so, what is the standard or accepted method to control the voltage of a variable 3 phase power supply? If there is no standard, what are some common methods?


texts: Stepping up voltage from solar for a power brick (5V to 15V) possible?

texts:
i have a 28mAh power brick capable of charging my laptop when charged.
I bought a 28W solar panel which outputs 5V over usb capable of charging ipads etc, however when i connected it to power brick's input it couldnt charge it (or at least charging light didnt come on)
Its only then i realised power brick is running off 15-19V 2A mains charger.
Is it possible to step up my solar panel to this voltage and trickle charge the power brick at all?


texts: Powering a remote circuit (operating at 5 VDC, 500 mA)

texts:
As per my application described in my earlier question, can someone please suggest whether I should power a remote circuit (placed inside a water tank on a terrace):

with a battery (AA/AAA batteries or Li-Battery or any other one, along with optional small solar panel for charging the battery)

or

using DC power lines that will be supplied from my home (5-10 m away from the remote circuit).

The remote circuit will most probably be working at 5 VDC with max current consumption of 500 mA.
I want to decide the same on the basis of involved complexity and cost of the above solutions that will be worth it for my requirements.
Any other/new suggestion is welcomed.


texts: What problems can arise from temporarily shorting power supply of a small microcontroller circuit?

texts:
A friend purchased a microcontroller-controlled lighting device and in the process of testing it, shorted the VCC and GND together for a second or two. Coincidental or not, the device stopped working thereafter, and he asked me if shorting the power could have been the cause.

It is my understanding that such a short could only really pose a threat to the battery or power supply (or the wire involved on the power supply side), given lack of current-limiting options or a fuse. The device should only experience power loss.

Can a power supply short cause a small circuit to permanently fail? If so, how?

I explained that the circuit might have failed because of the nature of the short: two wires making brief, intermittent contact. It might have created repeated instances of high inrush current which normally only happens once during power-on. Though, I doubt this theory because there shouldn't be much inrush current on subsequent power-on "events" as not enough time has elapsed for capacitors to discharge, etc.


texts:
Opamps are a great device for amplification. Recently i used a TL084 which is quad-channel Opamp
I used three opamps in the device for getting gains of 1 , 2 , 3 respectively. I noticed that, without any connection to the input, there was Voltage at the output of 0.4V. Please Help me understand what the problem is. Can a Pull Down Resistor help here? and also will a Series resistor to the input help? Please suggest good practices for the opamp design.


texts: Best way to connect 2 pins that are next to each other?

texts:
The two pins are next to each other and they must be connect together.

How should I do that?

Just connect them together with a simple trace?

Or pour them together?


texts:
I find something weird going on in my 100MHz oscillator probe.

I always thought the probe has a resistance of 1M ohm, but apparently at 13MHz, when I put a 2.2k ohm resistor in series with the probe, the reading is severely reduced. Does this mean that the oscillator probe is actually something around 50 ohm or so? But that would be impossible because 50ohm connected to the circuit would alter it's operating point too much.


texts: TowerPro SG90 servo motor: adding analog feedback

texts:
TL;DR: Where exactly did the Hexy guys connect the feedback cable?

I would like to:

Remove the 180° limitation of those servos. Did that with an instructables tutorial (TL;DR: remove piece of plastic from gears and potentiometer to let it spin 360º).
Read the actual position via some analog cue present in the servo board.

What I've tried is connecting a couple of pins from the servo's AA51880 to analog pins A0 and A1 of an arduino:

Here's the result when plotting pins Rdb and Pot from AA51880:

All screenshots are just with the default servo initialization as coded in johnny-five.io with Arduino's Firmata:

  var servo = new five.Servo({
    pin: 9,
    startAt: 90
  });

No sweeps nor movements are coded to drive this servo.

Then, when I perturb the servo manually, the servo spins a few times on its own (presumably the AA51880 correcting position) and the readings look like this:

And this in a different timepoint and position:

I also get spurious, uncontrolled spins of the motor when not actuating it at all. Is it possible I'm injecting noise to the board? Should I add a pullup resistor somewhere in my setup?

The question is, given the above readings, is there are way to reliably read the voltage/position of those cheap servos using the arduino ADCs while removing the 180° limitation?


texts:
For a simple AM, we multiply a low frequency message signal ( \$\sin(t)\$) with a high frequency carrier (\$\sin(10^6t)\$) to produce two high frequency signals :
$$\sin(t)*\sin(10^6t) = \dfrac{1}{2}\left(\cos[(10^6+1)t] + \cos[(10^6-1)t] \right)$$

I'm hoping there exists a similar formula when we do PWM, but wiki and other sources talk about many other things except a formula like above. So I'm posting this question here. How to represent the output of the comparator waveform mathematically ? Like, the input modulating signal is \$\sin(t)\$, and the input triangular waveform may be some piecewise linear function ? Then what will be the expression for the comparator output ? I mean exactly what frequencies does the output contain ?


texts:
I am working with an ATmega328. What I want to do is finding a way to save any value in any GPR of the microcontroller using the PC.

I found this video where an already made interface is shown. Apparently, that is very user-friendly. But does it what I'm trying to achieve? For example, if I want to save the value 0x3B in register R16, could I use that software to do it via USB?

Also, I don't know how to connect the USB with the microcontroller pins. I've found this image

but I would have expected the pins TXD and RXD to be used. Is this connection alright?

Sorry if the question is a bit messy, I'm a beginner with this stuff. If you need any further information please let me know.


texts: Power gain values at the microwave amplifier

texts:
I have generated graphs in AWR software for signal gains, G_A, G_max, G_P and G_T, respectively. The amplifier I am using is "HMC141". Unfortunately, the values that came out look like this:

When I add impedance matching at the output (marked "2" in the picture below), the gain values come out well below zero.

Is this possible?Is it possible for the gain values at the amplifiers to come out negative?  Is there an error somewhere? If so, where?


texts:
Please take a look at the picture below.

You can see that Samsung integrates SATA 3 into the Exynos 5 Dual. So does that mean that smartphones which use Exynos 5 will be able to connect to hard drives or optical drives by using SATA interface ? Do I misunderstand anything ?

And also, does DMA in the figure ("32x DMA") refer to "Direct Memory Accessing" ?


texts: increasing voltage using operational amplifier

texts:
I want to build own circuit using operational amplifier and resistors. I have 12V power source  (car accumulator) and 6V input voltage (Vin). I want to get 12V Vout and 25W at the output. So that is about 2A current(25/12=2).

I heart that operational amplifiers (OA) work only in low currents. Therefore I am not sure that it is appropriate to use OA to implement my aim.

My aim is to get 12V voltage and 25W power at the ouput from input voltage Vin=6V and 12V power source(car accumulator) using following circuit

So is this appropriate circuit? If, no can someone provide alternative curuits?
Thanks!


texts: Why do some IC pins have an asterisk behind them?

texts:
I am learning Arduino and one question asked what Arduino NANO's assignment of ATMEL's PD1* pin is. What does the asterisk mean in this context?
Edited to add NANO


texts:
How may I deduce the time constants from these output waveforms?
For \$V_{o1}\$ may I write \$\tau=1/2\pi f\$, where \$f=1/T=1/1ms=1KHz\$?


texts: How to convert 5v from a usb battery pack to 2.4v~3v for use with a 2xAA powered photo camera?

texts:
I've been having bad luck for years with rechargeable batteries which keep dying or don't hold charge for longer than a few minutes, or the charger for them stops working, and it's gotten to the point where I've spent 4 times more money on the batteries and chargers than the camera's own price. So I want to try something new − using 5v USB portable battery packs instead of the 2 AA rechargeable batteries. The camera has a plug hole for a wall socket 3v adapter (label on the bottom of the camera says 3.15v⎓) but that is not a mobile solution. But this hole can be used more easily than the AA battery contacts behind their protective cover.

I have basic soldering skills, but not enough knowledge about electronic components to figure out for myself what to use to make a circuit to do what I want. If you can post a complete noob-friendly answer, that's be wonderful. If you can point me at some starting places, that'd be great too.

An important thing to know about the expected power output of the circuit: apparently, standard non-rechargeable batteries will never work with a photo camera, as it will say "replace batteries" with any brand new pair fresh from the store. They don't seem to support enough output to power the camera's lens motor.


texts:
please help me about this project. I want to make electronic bell. Which duration time is like

10.45 AM to 11.45 AM ..1st lecture
11.45 AM to 12.45 PM .. 2nd lecture

12.45 PM to 1.30 PM lunch break

1.30 PM to 2.30 PM .. 3rd lecture
2.30 PM to 3.30 PM .. 4th lecture
3.30 PM to 4.30 PM .. 5th lecture
4.30 PM to 5.30 PM ..last one

I want to make project based on IC 555 and decade counter. But I have no idea about this. Please help me guys how to make project for duration 1 hour .


texts: Choosing TRIAC snubber resistor for multi-purpose switching

texts:
I'm designing a circuit to switch a 240V AC load and haven't done a lot with AC power control before. I'm planning to use a Fairchild MC3043-M optically coupled TRIAC driver along with a BT138-600 NXP BT138-600 TRIAC. Referring to the following diagram from the datasheet:

The comment is made that for highly inductive loads (power factor < 0.5), change this value to 360R. One load I'm switching is an AC fan (0.8A) which is obviously inductive although I have no idea of the power factor likely, and the other is a router using a 20W switching supply.

My question is to make the circuit universal considering it's not for a commercial product design and I may use for other purposes in the future is there any disadvantage to always using a 360R (well guess I'll use 390R) other than needing a higher power rating for the resistor? Also any hints on calculating the power dissipation through the resistor assuming a 5A load which is what I'm planning to use as a fuse value?


texts: Understanding phase noise specification in signal analyzer

texts:
I'm reading this datasheet and I see that phase noise is specified (page 12) in dBc/Hz for several offsets.

I understand that that "Hz" in the unit means that the value is specified normalized to a 1 Hz RBW. How do I find my phase noise for other RBW? Is it just scaling the value in the datasheet by the appropiate frequency?


texts:
"earth" is connected to exposed touch-able parts on this  coffee grinder. It does bite! It has the double insulated mark which per my standards is incorrect.

It has an unearthed input.
Schematic: http://imgur.com/QYaudyJ


texts: what exactly is this component and what the marking on it means?

texts: my car stereo (audi rns-e) showed a blank white screen, took it apart and the outer part of this component was rattling around. i want to replace it to see if it was the problem, but i dont really know what this actually is. looks like a coil or inductor, but googling the marking i got no results.


texts: How can I bench test a Flame Sensor (Flame Rectification)

texts: I am troubleshooting a gas heater and all test results point to the flame sensor but I would like to bench test the flame sensor.  Any ideas on how I might set up a test environment with on-hand materials like maybe a burner (camp stove, bunsen) and power source, then stick the flame sensor in the flame and compare the uA current to spec?


texts: compare high power mosfet for high power load

texts:
I'v been searching mosfet for high power load project (DC 110V 100 Amp) and I found Fairchild FDL100N50F (TO-264) with maximum Power Dissipation 2500W.
According to data sheet, the Max SOA DC (continuous not pulse) at 100v is around 20A, my question is, considering the package/dimension is it really safe to apply 100v at 20 amp, do I really need mosfet in SOT-227 package such as IXFN82N60P which surprisingly (for me) has less maximum Power Dissipation @ 1040 W.

Thankyou for your answer, and pardon my english


texts: How do "beyond the rails" analog switches work?

texts:
I'm familiar with using CMOS switches ("transmission gates") for switching analog signals, but you can't use them for switching voltages beyond their supply rails.  (So if you have a single supply circuit, and a voltage signal that's been AC-coupled and to a ground reference, you cannot use a CMOS switch because the voltage of the signal drops below ground, which is the negative supply for the switch.)

However, there are some analog switches that will switch ±25 V signals with a power supply of 0 V and +3.3 V.  How do they work?  Is it simple to build a circuit like this out of discrete parts?


texts: How to regulate a flyback transformer to have output of 100mv or 200mv ripple?

texts: I see spellman/bertan hv power supplies achieve this but are expensive. Is there a circuit that can regulate cheap flyback transformer's voltage ripple just as well? I've seen some circuits referred to as smoothing circuits and filter circuits but it's hard to find quality search results that actually mention design related to voltage ripple control. I would only need around 30 uA to 400 uA.


texts: Amplify an Electret Microphone using an input Jack 3.5mm

texts:
First time on the platform, I will try to be as clear as possible, and electronics is a hobby for me, so I'm open to any welcommed criticism.

I'm trying to build a little project, recording the sound coming from a stethoscope, and then transmit that sound to various devices (laptops, smartphones, desktop PC) via the jack input of said devices.

I bought multiple electret microphones (list below), and did some tests by simply wiring my mics to a jack cable as follow :

Technically, it's working, I do get sounds, I can tap on the stethoscope and get a feedback (on Audacity or something similar) ; sadly, it's VERY low, and the sounds I'm trying to get (heartbeat, lungs sounds, ...) are very faint, and those results are across all mics I have.

I tried various schematic I found, but most either require an external PSU/Battery, or don't work (as far as I tried and didn't wrongly made those).

So my question is : How can I amplify / add gain to my mic signal without sticking a PSU on it ?

Or maybe, I'm going in the wrong direction wanting to use an electret mic ?

Thanks in advance to anybody trying to help !

Mics list :

724-3138

KECG2738PBJ-A

KECG2742WBL-25L

KEEG1538WB-100LB

KECG2742TBL-A


texts: Find the current in the circuit after 20s if the initial current was 0

texts:
An inductor in an electric circuit is essentially a coil of wire in which the voltage is affected by a changing current.  By definition, the voltage caused by the changing current is given by \$V_L=L\dfrac{di}{dt}\$, where L is the inductance (in H).  If \$V_L=9.0-0.01t\$ for a 3.0-H inductor, find the current in the circuit after 20s if the initial current was 0.

I am trying to figure our where to start.  Would you integrate \$9.0-0.01t\$, multiply that by 3H, then plug in 20s for t?


texts: Understanding these Mosfet Data sheet Specs

texts:
So my local electronics store has a catalog of MOSFETS they sell.
I’m having a little trouble interpreting some of the specs.
In particular:
“gate to source cutoff voltage” Where it says 4V MAX, does that imply that 4V is the maximum VGS will take before problems? What is VTN? And can I turn it on with say 5V from an arduino output pin?
And “drain to source breakdown voltage” where it lists 100V MIN. Does this imply that 100V is the minimum VDS? Can I use lower voltage for the power supply? 10V for instance?


texts: In the recent Con-Ed transformer "fire", what exactly produced the color of the huge blue glow over New York City?

texts:
Blue is often linked with technology (e.g. "big blue", glowing pools of water with Cherenkov radiation, aliens in general, Nobel prizes for blue LEDs) as well as traditional things like sparks.

In a huge transformer "fire" event like this, what causes this blue light? Is it related to chemicals contained in the transformers the way chemicals affect the color of fireworks or how carbon molecules make many comets blue/green? Or is this really coming from huge electrical discharges through the air and certain spectral lines excited in nitrogen or oxygen compounds? What exactly makes this blue?

Video and audio: https://www.youtube.com/watch?v=6G4dYRcKnVE

BETTER video and audio, stars out variable yellow/orange but after about 1 minutue settles down to beautiful, calming, stable turquoise flames! https://www.youtube.com/watch?v=sr7QkttzX-Q

Another video https://www.youtube.com/watch?v=PRYblAiSQ_8

Images from CNN's A transformer explosion turned the New York City skyline blue


texts:
We have found that our two EVs are tripping the 32A MCBs in our Consumer Unit, but from my basic knowledge the 2*6.6kW chargers on UK 3-phase should only draw about 19A.

I've measured the power consumption by timing the meter disk1 and each car draws about 6kW (the two at the same time on two different circuits draw a total of 13kW).

\$ I = \frac {P} {3 \times V_{LN}}
= \frac {P} {\sqrt{3} \times V_{LL}}
= \frac {13kW} {3 \times 230V}
= \frac {13kW} {\sqrt{3} \times 400V}
= 18.8A \$

I can't believe that EV charging has a power factor of 0.59, but another question - MCB of desired rating - alluded to MCBs having low tolerances (20A MCB tripping between 18A to 25A). Is this correct?

The charging posts we have are two 2x22kW Rolec Autocharge posts. Our director likes to buy big (futureproofing being his motto)... but because of lack of total capacity into our building our electricians limited the supply to the posts to 22kW each (using a 32A MCB). Still, our current 13kW usage falls well short.

1 Meter is 60 revs / kWh. Measure time for 5 revolutions with no EV charging load, and use that as our base usage (5 rev in 20s = 15kW). Then attach one EV, wait for load to settle (5 rev in 14s = 21kW). Difference is 6kW.

RapidTables Kilowatts to amps calculator


texts:
How can I design a PCB in order for it to have this kind of PCB Tinning finish?

I do know this decreases the resistance of the tracks and increases the amount of current it can handle however

Do I need to leave the solder mask below and do it by hand?

Do I need to remove the solder mask ?

Can this process can actually be done at the fab house?

Edit 1-----------------------------------------------------------

Now an interesting question, Is there any kind of design rule to follow using this HASL finish? , I mean the rule its 40mils per Amp however if I get a 40mils HASL finish track, can I actually put 2 Amps on that?, if the answer is yes, isn't the solder conductivity lower than the copper itself?


texts:
I have an old 36v DC battery hydraulic indoor forklift.

The batteries are 23 years old, and no longer hold a charge for more than ten minutes, although they are a good counterweight.  I have tried keeping them charged, but it just chews hundreds of dollars in power.

The forklift itself is quite useful as it's a compact reach truck with 4 metre high lift, in good complete condition. I only want to use it once a week in my small warehouse and front loading bay, about 30m long in total.

I priced new batteries, many thousands, or used batteries at least a thousand, and would still require frequent charging.

So I wondered about a DC rectifier supply, with a long mouse tail or catenary overhead wire feed.

The batteries are 2 units of 9 cells x 2v = 18v rated at 387amp hours, 5 hour rated.

Does that mean they can deliver approx 5kw continuous work per hour for a 5 hour shift?

I hooked up a medium size DC welder to the hoist, but it barely makes the hydraulic lift motor turn, and the drive motor won't start at all. It's rated at 135 amp 30% duty, or 74 amps continuous at 47vdc. 30% would be fine, use is very light.

I figured I could just look at the DC motor rating, but for the hydraulic motor I can't see any plate, and the drive motor is a wheel hub motor, and I can't see any plates on it. The DC feeds after the electro-mechanical relays are all about 1/2" diameter including jacket, which gives an idea of the draw.

My real question is how big a DC power supply or rectifier do I need to get this unit moving? Will some big old capacitors help by buffering the rectifier from the DC motor start current? Would capacitors with the medium welder work?

I was thinking a large old 3 phase DC welder, something that can deliver 200 to 300 amps ought to do the trick, but unfortunately isn't very compact. I was hoping to mount the welder to the roof of the forklift so the tail is AC, and doesn't suffer the low voltage power drop over a long cable.

If it's just not going to be mobile enough I suppose it would work as goods lift to a mezzanine floor.

The other option is give up and scrap it, wreck it or sell it, and get a manual or walk-behind unit.

TL;DR - Recycle or repurpose way of getting a few hundred amps DC @ 36v


texts:
I want to ask, when choosing resistor for a LED, how to choose power of the resistor(for example in SMD applications).

For example:

1 LED 2.0V FV 20mA
Resistor 65 Ohm
Power supply 3.3V

With this configuration I've 20mA through resistor. Now, LED dissipate 0.04W. How I can choose correctly resistor power rating?

I should refer to LED power of 0.04W and choose a resistor of at least 1/20W? Or refer to current through line(3.3V*0.02A = 0.066W) and choose a resistor of at least 1/10W?

Should I apply a safty factor?


texts: Let say I have IT equipment that is rated for 100V to 240V.  I plug it into a 208V receptacle that it unprotected (no UPS or surge suppression).  What would happen if there were a voltage sag on 40%.  the incoming voltage would drip from 208V to 125V.  Would this cause my IT equipment to fail?


texts: MBED + STM32F446RE: can't call function in RAM

texts:
If I try to put a method in the .data section using the below code, the microcontroller hangs when I try to call it. Is it a wrong way?
(When I check in the disassembly it appears indeed in the RAM)
__attribute__((long_call, section(".data"))) void my_ram_method() {
   // Do something
}


texts: What exactly is the point of specifically 'inverting' buck/boost converters?

texts:
I'm planning on generating a negative voltage for a circuit i'm working on, and want to use an inverting buck topology to do this. With the application being battery powered, my primary concern is efficiency.

Whilst looking at the many options available, I've come across parts that are marketed specifically as inverting regulators (such as the TPS63700). Considering that a normal buck converters can be modified very simply to become inverting regulators, what is the point of these parts? I would guess that its because the parts deal more specifically with the design considerations of adapting to a inverting topology (such as the need for wider input voltage ranges), but its just a guess.

Going back to my application... since I've found very high efficiency (~95%) buck converters that seem like they could be adapted to my application easily, should i just use them instead of these specifically 'inverting' regulators that generally have 10% lower efficiency (because the product pool is smaller)?


texts: Comparison of the efficiency of DC motor current limiting / control methods?

texts:
I'm using the wheels and motors of an RC toy car as a simple robotics platform. The car has 2 motors, one drives the back wheels, the other steers the front wheels. The steering motor is stalled by design when steering, it is blocked at a fixed angle by the plastic chassis. It draws 0.85 A when stalled (i.e. anytime when steering).

Due to this marvel of toy engineering I have to use an oversized motor driver IC (L293B – 1A continuous) and this motor draws about 3W of power (0.85A x 3.6V). I’m using this IC to control the other (“normally rotating”) motor as well, which appears to be the same type: 0.85A stall current, around 100mA no-load, and 250-400mA at normal loads.

Testing with various series resistors I have found out that 0.3A are sufficient to turn the steering wheels and keep them in position. Using a resistor might allow me to use a driver IC with a lower Amp rating (L293D – 0.6 A), however the same energy is still wasted, only as heat. While this is not a serious issue with this toy setup, I am planning to build bigger robots with significantly more power, so energy conservation and current control will be important in the long run, and motors may also stall accidentally.

Looking into DC motor current limiting, I’ve found the following approaches:

Series resistor – simple, cheap, bidirectional, wastes energy, dissipates heat
Current source with 2-3 transistors and sensing resistor – relatively simple, however I’ve only found unidirectional circuits, which would get shorted when switching motor direction. Is there a way to use this method bidirectionally? (and/or with a 2-channel H-bridge IC?  - I cannot place it before the ICs common supply, because the 2 motors draw different currents).
Example: Designing a current limiting circuit for my project
Chopper circuits/PWM – Will this reliably protect the IC from overload? Is it energy-efficient?
Are there other other methods I am unaware of? Something on the principles of switching supplies?
Would it be simpler in my application to use 2 separate drivers/h-bridges and place a voltage divider between them, so that a lower voltage is provided for the inefficient stalling motor and more to the one that moves the robot?

So how do the above  methods compare in terms of efficiency and simplicity of design? What is the preferred method in robotics/other DC motor applications?  Also, is it standard practice to limit DC motor current, or a motor is most efficient if allowed to draw as much current as it needs? Is it acceptable to use a DC motor that is mechanically stalled by design, or is this only used in cheap crap toy cars?


texts: Cannot change to front copper layer in KiCAD

texts:
I am learning to design PCB using KiCAD. I followed a tutorial on youtube.  I got stuck at changing the layer of the PCB. From the video, the layers can be interchange by pressing page up (front copper) or page down (back copper). My filled zone layer is b.cu and net is GND. The B.Cu layer is just fine but when i change to F.Cu layer, it is still the same as before.

I have inserted a picture showing my issue. As you can see the selected layer is F.Cu but it is showing the back side. What have I done wrong and how can I change to front layer?


texts: In a common-emitter amplifier, under which conditions are we supposed to use one equation over the other?

texts:
Under which conditions am I supposed to use a particular Ric equation in order to calculate the total output resistance of the amplifier? I don't know which one to choose when. Can someone give me a straight answer? I am using a standard (NPN BJT) configuration.

This Ric?
Or this Ric?


texts: Safety: Mains step down transformer vs SMPS for bench power supply?

texts:
Between a mains step down transformer and a SMPS, which would be safer for a bench power supply? I cannot look inside the transformer in either case to judge the insulation quality. But, if the insulation does fail there would be 230VAC at the secondary for the mains transformer. And, maybe 325VDC at the output of the SMPS (is that possible)? I can visually inspect the SMPS PCB to check if there is proper clearance, presence of MOVs, thermistors, fuses etc, but of course cannot see inside the transformer.

So the question is, which is easier to make safer (or screw up)? Which is easier to figure out when new, if failure will be catastrophic in future? Can SMPS transformers fail due to failing mosfets etc? I'm guessing that if a mains transformer works without issues when new (including the problem of interwinding capacitance), I can expect it to work for at least a decade without issues, right? Assuming everything will be fused properly and fan cooled.

It's one thing to get a shock from inadvertently touching bad wiring, and quite another to be exposed while clutching the wires in my hands. So I am concerned somewhat about safety. Of course, an RCD/RCCB should probably be put in, but I don't have that yet.

[PS: I'm planning to put a buck converter and then a linear regulator to drop and adjust the final output voltage, be it the SMPS, or the mains transformer.]


texts: Free simple application for making a prototype shield

texts:
Is there a simple and free application for 'designing' a prototype shield (like this?)

Currently I use Excel and a 'Above' and 'Below' side next to each other but it gets messy already with such a small shield layout.


texts: Redesign circuit to use LM317 instead of MFC 6030

texts: I have a failed obsolete adjustable voltage regulator (Motorola MFC 6030). Could this 6-terminal device be replaced with a modern 3-terminal voltage regulator? The regulator is used to drive the base of a pass transistor for a DC power supply. The power supply (Heatkit HWA-202-1) delivers 10 V DC to 15 V DC at 2 amps.


texts: How do power stations maintain 50 hertz?

texts: In the UK our mains standard is 230 V AC at 50 hertz. So I understand that the generators at the power stations need to spin at exactly 3000 RPM . This is true no matter what the source is (nuclear, coal, gas, hydroelectric etc). Let's use steam as an example here. How do they use the steam to spin the generator at a constant 50 hertz? It doesn't seem plausible to control the speed with the amount of steam passed though to that precise speed. So how do they do it?


texts: Help with designing a suitable 12-to-5 V voltage converter using an op-amp and a diode

texts:
The question ive been given:

My work up to now:

However, I do not know how to calculate the values of R1 and R2 (assuming I am correct up to now). can someone point me in the right direction such as the correct calculation or an example. I really appreciate the help.


texts: Implementing my own ESC (electronic speed controller)?

texts:
I have a project that uses an ESC to run a brushless motor (Hobbyist RC plane sized, 24 gram, 1300-1500 KV).

I would like to experiment with eliminating the ESC and driving the motor with my own circuitry and control software.  Are there any good tutorials or other starting points?

(I realize it's more practical to just keep using my $8 ESC, but I'm interested in this as a learning exercise.)


texts:
Few years ago I bought "pack of SMD capacitors", they came only with information about capacitance and voltage. Now I need to use one of them, but I have trouble with find information what exacly they are.
I found RVT series from ELNA, acording to datasheet it should be 12.5x13.5mm, but my are about 7.5x9mm.
Are they fake?
Datasheet: http://www.elna.co.jp/en/capacitor/alumi/catalog/pdf/rvt_e.pdf


texts: large inductance compensation methodology in chip power delivery network

texts:
i am trying to learn on compensation networks design.
Suppose our power delivery network from VDD to the chip has very high impedance at certain frequency.
i know that we cn use smith chart to design such network.
i dont know the exact terminology or if smithchart is the best way.
i'll be glad for a recomendation on methodology for these purposes.
Thanks.


texts: Difference between real binary value and oscilloscope value

texts:
I tried to see an ASCII "A" character with an oscilloscope but the real binary value and oscilloscope values are different why is that? ASCII "A" Binary value - 01000001

The oscilloscope displays this graph:

I use an Arduino Uno to send the ASCII value using the code:

void setup() {
  Serial.begin(9600);
}

void loop() {
  Serial.println("A");
  delay(1000);
}


texts:
This link states that when determining the power needed by an amplifier, you use the following formula:

I understand that the second term is due to the quiescent draw of the amp, but how is the first term derived? Where does the pi come from? I would have imagined it would be Vopeak^2 / R_L, since that is the peak power into the speaker.


texts: CD-ROMs open/close in response to sensors

texts:
The general question:

How can I open and close CD-Rom drives (about 20-30) in reaction to various sensor input?

Some more specific questions (based on the assumption that I should to tackle this with an Arduino):

How would I go about figuring out which pins on an IDE connector are the ones that need to receive a signal?

How would I figure out what signal needs to be sent to those pins?  And how would I make an arduino send that signal?

Some context:

I'm working on a pine tree kinetic sculpture made of old CD-ROM drives. Basically, each "branch" of the tree is a CD-ROM drive pointing away from the trunk. The drives will open and close based on feedback via:

A microphone. An algorithm would open and close the drives based on analysis of the audio input. One idea, blowing into the mic (like the wind) would simulate the wind blowing pine tree limbs (they would shutter open and close)
Alternate (or perhaps complementary input): a small model of a tree with touch sensors. If you put your hand around the entire small tree and cover all the sensors, all the drives close. Basically, each sensor is mapped to one drive, cover it and the drive closes.


texts:
I have a single +12V input, and am creating two separate +5V supply lines from it.  Using the datasheet and TI WebBench, I chose values for the input capacitors.  However, with two regulators, all the input capacitors are essentially in parallel.

Example:

My question is:  Do I need to consider any changes to the input capacitors?  Or, would it be typical to put diodes in front of each regulator input (before the caps) ?


texts: Little confuse about the truth table about D-flip flop

texts:
I am a little confused about the Truth table of D-flip flop,and i want to figure it out.

According to the d-flip flop in wiki:

D-flip flop with set(S) and reset(R):

If S=R=0,Q depend on clk and D,when clk is Rising edge,and D=1,Q=1

If S=1,or R=1,Q depend on S or R,when S=1,means set Q=1; R=1,means set Q=0

If S=1,R=1,Q depend on nothing,Q=1,Q'=1

But,if d-flip flop with reset,(no set here) ,when R=0,Q is not always 0,when clk is Rising edge,and D=1,Q=1

But i see the waveform in this picture,and the waveform is not the same as the the wiki said,can anyone help me figure it out? The picture is from this website:
http://macao.communications.museum/eng/exhibition/secondfloor/MoreInfo/FlipFlop.html


texts: How to choose an external powersource with electronic logic

texts:
I am a n00b in electronics (software developer)

I have 2 batteries bat1, bat2 (1.5 volts) available to me. I can only use one battery in my circuit. Let's say that if the  battery is put in a holder such as  then it starts working

If I want to connect one battery (bat1) I just put that in. If I want to put the other battery (bat2), I swap the old one and put in the battery (bat2).

Now I want to do all of this but electronically. I really don't want to replace that battery with a robot :). Rather electronically start using the second power source.

This question is not about choosing a backup power source. It is just about choosing what ever battery you want at command. Also This could be between 100 batteries.

Makes sense ?


texts: Different trace width signal transmission line

texts:
I have a really basic question. I am wondering what happens physically with the signal, if I have a change in a trace width (see picture below).

My point of view is that you have a reflection of the signal, because of the different impedances. But I have heard that you can change the width for impedance matching, which you would need to reduce signal losses. However that would be contrary to the mentioned reflection. Can someone help me?


texts:
We are working on communication between AVR and a Crous PTZ.

We can see some details about Crous communication ports on page 15 of its guide :

We found Crous protocol doc (Got it here) and now we can turn it on and so ... just via Optic port but not RS232 port yet.

These details we applied in RS232 communication:

1 - Crous rs232 is connected to rs232 port of PC and communication has been tested with&without MAX232 .

2 - Ground of Crous power is separate ,  (PC RS232 & Crous RS232 grounds are connected to each other).

3- All voltages applied are 12 V .

4 -Oscilloscope has been used and it shows only a puls is sent to device but does not show any respond from device

What's your opinion ?why there is no respond on rs232 port?Cours device is new , so is it probable its damaged ?


texts: choosing the right power adapter for LM317 regulator for battery charging

texts:
I looked at the standard LM317 setup at http://www.learningaboutelectronics.com/Articles/LM317-voltage-regulator (where the center of a voltage divider is connected to the adj pin and the inputs and outputs each have their own ripple filter capacitors).

What fooled me was when I used a 12VDC adapter to power my charger circuit, the voltage reading from the voltmeter was 18VDC even though the label on the adapter is 12VDC.

I used the same LM317 setup to try to achieve roughly 7.5V (but my R1 is 330 ohms and R2 is 1800 ohms and both are 1W) but when I used my 12V adapter, the measured output voltage was 10.5V which makes me think I'll explode my batteries since I'm charging two at a time and each one is 3.6V nicd.

I then proceed to read http://www.apogeekits.com/power_adapter_selection.htm and it states that my circuit must use the same current the adapter must provide (800mA) in order for the true voltage to be read from the adapter.

It also states that the adapter I have is unregulated. Rather than me trying to find (expensive) regulated adapters, is there a way I can alter the simple LM317 circuit or even change from one adapter to another so I can see 7.5V at the regulator output? or can I keep my existing setup and increase some resistors?

Eventually I'll have a complex circuit and for the most part, the maximum current consumption for the output elements will be in the order of milliamps.

This is the initial question to the charger I made:

What causes the opamp to become warm in this charger? [question updated]

but I made a new post because my problem now is directed to the power supply.


texts: Difference between placing unidirectional TVS diode before fuse or after P mosfet

texts:
In the buck-boost converter I am finishing, I came out with this question.
At Vin (12V in my circuit) I place a 7A fuse and a P mosfet (IRF5305) to prevent reverse polarity issues.
Because I want to protect everything after these two components (if more than 12V is applied at Vin), I want to place an unidirectional TVS diode (Vishay 1N6376-E3/54) between Vin and GND.
Does it matter if this TVS diode is before the fuse or do I have to place it necessarily after the P mosfet?
This is the actual schematic without the TVS diode. (Dissmis the "-" on +12v)


texts: Sizing zener and resistor for solenoid flyback

texts:
I am trying to drive a vibratory pump from a 220 V boost converter (the common 150 W DC/AC 12 V to 220 V boost converter found on ebay) and a MOSFET switched by an Arduino/optoisolator at 50 Hz. The pump can be considered a solenoid and a video description is available here.

I arbitrarily chose a 2N60 MOSFET because it was the first one I found that was cheap and had a 600 V breakdown voltage. I assume there is a better and cheaper MOSFET I could have chosen (feel free to suggest a better choice).

If I can trust some of the blogs I have read, the pump has a measured inductance of 854 mH and a series resistance of 165 Ω. The power draw is rated as 53 watts. I am told that a simple flyback diode will reduce pump pressure and that a diode plus a 10 W 220 Ω resistor will allow full pressure although the resistor will get a little hot. I am thinking that a zener will improve the power dissipation but I am not sure how to choose good values for the resistor and zener.

I am trying to keep the circuit cheap, physically small, and not outrageously hot for a closed box.

Is there a better way for me to do this? I assume that a 600 V breakdown voltage still needs some flyback protection.


texts: Does electricity go from negative to positive or vice versa?

texts: It's common knowledge that electrons flow from negative to positive, but I have noticed than often the direction of the current is ignored. For example, the resistor is often put AFTER the LED, or the diode is put the opposite way. Why is the direction of flow often disregarded in electronics?


texts: Positive and negative rail for op amp circuit

texts:
I need a positive and negative rail to power an op amp

Since it's an op amp for a voltage reference, would using a circuit like this one be enough?

Input voltage is unregulated 37 volts, with 4.7k resistors; current is about 7.8 milliAmps

Since the op-amp is needed as the error amp for variable output voltage, the op-amps supply voltage will be unregulated.

Are there any pitfalls that I should be aware about? Any other topology?


texts:
Currently, i've been trying to work on virtualizing a motherboard from an old Lucent BZ5000 equipment, my idea is to emulate the BIOS from that equipment on a modern PC and be able to connect physically to the PC:

-A Memory Controller Card:

PCI card with a FPGA and some EPROM that technically works like an old USB where you load software.

-A SCSI Card:

The one that the system boots in, this is the one that searches for the Memory Controller Card.

The BIOS is an Award 4.0 BIOS, and from what i've seen, Phoenix makes kinda the same BIOS now.

I need to emulate the specific BIOS or another one with an SCSI boot option.

Downside is that electrical engineering is very different from the software engineering i learned, but i've done my best research to find my answer, the best i've done is running the BIOS of the board through a software that runs the ROM file like software, but not recognizing PCI ports and such, and finding QEMU, an emulator/virtualization tool that from what i found, is able to run firmware.

So is it posible to emulate Firmware, more specifically, a BIOS? cause searching through the web, i only find emulators for Video Game consoles BIOS and ROM files.

Thanks,

Diego Jarquin.


texts:
To fulfill customer expentations and fill out customer reports about the device, is there also one section about CPU Utilization. Because I have never done such task before I have overview some "Google Search" articles. A lot of the articles are in direct connection with Linux programming, a lot of them speak generally about CPU Utilization (just theoretical) and I didnt found no article about the method how can be this done .. okay there are some: embedded.com.

I am interested how YOU have done such task timing job before? I am intereseted in method and also whit which tool was done? With some direct measuring on the osciloscope (or logic analyser) or capturing data from osciloscope and post processing them? Which time frame to take for CPU Utilization to calculate - most "busy moment" when all interrupts are present, because in this case CPU utilization is much bigger then maybe 1 milisecond or 1 microsecond later, when only the background loop is executing?

Maybe for reference how I have made my first CPU Utilization approach (I don't know if is the right approach):
Every interrupt when start executing have dedicated PIN which goes high when interrupt begin and gets low when interrupt ends. There is also same propagation delays involed. I export this signals over the osciloscope into one file and post-process with octave. There is still an issue which timeframe to take.

In case of any question please write in the comment section


texts: Effect of Source and Load Resistances on a Filter

texts:
suppose I want to design a low pass filter (for instance a Chebyshev filter) by using the low pass prototype method:

The upper circuit is the Low pass prototype filter, while the lower one is the real filter (which is obtained from the first one by using a frequency and impedance de-normalization).

As you can see, the "effect" of a filter on the input signal does not depend only on the filter (i.e. on its transfer function) but also on the source output resistance and on the load.

Now suppose I want to realize the same transfer function with an active filter, such as the Sallen - Key Low Pass filter:

As you can see in Wikipedia page, there are the following design equations which can be used to realize a second order low pass transfer function by choosing w0 and Q.

So, it seems to me that if we design a filter transfer function with the second method, it will be ok for any source output resistance and for any load. It seems quite strange to me and it seems in contrast with the fact that the filter realized with the first method depends on them.

Maybe the dependence on the source and load resistances is hidden and I do not see it.


texts: EAGLE: Change shape of Repour All Polygon

texts:
As you can see from the attached picture, I used some polygon area on the top side.

Anyway, the surface has some empty zone close to pad that I would like to fill with copper.

Do you know how to do that?

Thank you.


texts: Confusion in power formula of transmission line

texts:
Here i am confused whether i have to use the formula for power is

  \$P_l=\frac{V_i^{2}}{Z_0}(1-\Gamma_{l}^2)\$

OR

  \$P_l=\frac{V_i^{2}}{2Z_0}(1-\Gamma_{l}^2)\$

if i am using the first formula answer is matching but power should be calculated for rms values so in my view power formula should be 2nd correct.

please help me with this confusion


texts: Why there is many configurations of Colpitts oscillator?

texts:
I would like to understand how colpitt's oscillator works but I'm confused because there are many configurations on the internet and I don't know what is the difference between them.

For the next two configurations, Why are the capacitors C1 and C2 are moved ? They where between the output ( collector ) and the ground and they became between the output and the Vcc.

http://upload.wikimedia.org/wikipedia/commons/b/bf/NPN_Colpitts_oscillator_collector_coil.svg

http://www.learnabout-electronics.org/Oscillators/images/LC-Colpitts-osc-01.gif

For the following configuration, I understand it very well because the feedback path is very clear.

Would you tell me where the feedback bath of the previous two configurations is ?

http://www.expertsmind.com/CMSImages/1892_colpitts%20oscillator.png

My last questoin is : Why we need to modify the configuaration ? which one is most suitable for radio frequency ? and which one has a stable frequqncy and works without errors ?


texts: Passive Level Shifter Needed - LVCMOS 3.3

texts:
The device that will be driving another device claims it is LVCMOS 3.3V but it doesn't appear to be. Here are the voltage levels of both parts:
VoH(min)= 2.3V
VoL(max)=0.8V
ViH(min) = 2.0V
ViL(max) = 0.8V
The problem is with the VoL-ViL where there is no margin. The device which is driving the other device realizes this and recommends a voltage divider like this
Unfortunately, this doesn't seem to work because now at VoH=2.3V, the ViH=1.56V which is below 2.0V.
I tried other combinations of resistor values but nothing working.
Can anyone recommend a way to get this interface to work with passive components?
Thanks!


texts: In my RC servo motor datasheet the shall current is 600 mA. My Arduino cannot supply that much of current so, I decided to use an DC adapter to supply the power and arduino to control the Servo. My question is - Can I connect a DC adapter of 5 volts and 1A to the servo. I have read some where that servo motor just take current (not voltage) what it needs even tough you supply more than enough. Is it right?


texts:
I've run into a dilemma. I have two motors, both with a 2.2A stall current. I know that at start up, motors will draw their stall current because they are essentially stalled. However, my motor driver is rated at 2A max per bridge (there are two), and my battery is rated at a max discharge rate of 3.5A.

Is there any way I can limit the stall current? Could I implement a sort of "soft start" using PWM to slowly turn the motor?


texts: What happens if an LED is connected to a supply voltage greater than its voltage drop?

texts:
My understanding of resistance and voltage is horrible. I heard that with Kirchhoff's law, (in my words, please correct) the voltage used by the circuit must equal the voltage supplied. For example, if I had a 9 V battery, I must use all 9 V of it.

Lets say I have a LED with a typical forward bias voltage of 3.1 V, which means it loses 3.1 V while generating light. Will the LED if 9 V is used, burn out?

It is most likely true, but a nice example will really make my understanding more intuitive.


texts:
What is the reason for using the transistor (2N3904) is this circuit? What good is this transistor doing in this circuit.What happens if we remove the transistor from this circuit? And what will happen if we use a PNP transistor instead of a NPN transistor.

so my explaination about the original circuit which I implemented because I don't have 50 OHm resistor.When there is light in the room, the circuit inside LDR is complete and hence all the current flows through 1K and LDR branch, and very low current is at base so the amplified current by 2N3904 is insufficient to lightup the LED. When there is dark in the room, the circuit of LDR is open and hence the base current of 2N3904 is maximum (2.3mA) which after amplification is 232.2mA which is sufficient for the LED to work. The LED has voltage drop of 1.8V.


texts:
Recently, I bought a DC 12300, a 12V battery with high capacity 3000mAh and I got a charger 12.6V and 500mA output. First thing I did when I got the battery, I measured its voltage and it was 2V. After 6 hours of charging, (I presumed that it was 3000mAh-6 hours of charging). I got the same result. But as batteries are all connected in series their capacity is still 1380mAh.

My first question is: Did I overcharge the battery considering the fact that I charged 1380mAh instead of 3000mAh? It says also "Over-charge/discharge protection".

I proceeded by measuring the voltage individually for each small battery and I got 3.7V and 0V for 2 others.

My second question is: Can I try to recharge the battery separately using a 4V charger or my battery is definitely damaged?


texts:
I'm soldering up some boards with smd parts, using a hot plate to reflow, and I'm (inevitably) realizing that I got some of the wrong parts. Now, is it better to leave the boards with smd components stuck on them (sitting in wet solder paste) until I can get the other parts, and then do the reflow all at once, or to reflow now, and then paste and heatgun (or just solder iron) the other parts in later?

I only have a few parts for which I need to do this, and I can stick the boards in a quiet refrigerator until I get the parts. I might not have ready access to a heat gun later, which is why this isn't a no-brainer (I'm imagining soldering iron+paste isn't the best way to do things, since I can't get to pads under the parts). Personally, I think the real question is whether reflowing twice negatively affects smd components, but context might prove it otherwise.


texts:
The problems seem simple, yet I fail to find an answer...

Is there a way to create custom flip-able layers in Eagle?

Some background on, what I'm trying to achieve:

I'm working on a project, which requires frequent changes and adaptions to the design. To make my life easier, I want to have a layer for assembly instructions and documentation, for which I create a custom Gerber output in the CAM file (one for topside, one for bottom side).
Like this, all assembly documentation is generated by the CAM output. Also when moving components, the related assembly documentation is moved as well.
I, of course, do not want this documentation on the "Value" and "Name" layers. Also, the "docu" layers are not suitable as I don't want all information from these layers to be in the assembly documentation.
Currently, I created a layer "AssemblyDokuTop" and "AssemblyDokuBottom" and added the necessary information to the parts in the library.
As long as the components remain on the same side of the boards as in the library the method works fine. But if I have to move components from top to bottom layer, the assembly documentation remains in the original side. This gets especially tricky when I have two instances of the same component on opposite sides of the board.


texts:
I am trying to reinvent the wheel apparently... I want to create a one-digit BCD counter that increases on a button push and resets to zero when reaches nine.
I have just finished a circuit for BCD to 7-segments encoder.

Can anybody give me the basic idea of how should I do this?


texts: Altium Turn Off Reset Net Colors on Updating .PCBDoc

texts:
I've been working in Altium sporadically, and I like to color my net connections.

Everyone once in awhile I forget to click the option not to reset my net colors when re-populating a .pcbdoc and I wipe out my net colors.

Is there a way in the settings to remove the option of resetting the net colors if you re-populate a board?


texts: Choosing a capacitor to buy (Mullard tropical fish substitute)

texts:
So in this post:
Figuring out a substitute for an old amp capacitor - value and type
I figured out the capacitor I had in my amp.

It was a
Red, red, yellow, black = 2 2 0 000 pf +/- 20% resin dipped polyester (Mullard C280).

In this post:
Mullard tropical fish capacitors
it was said that I shouldn't look for a vintage cap.
It has been also said that: "Exactly the same performance can be had from ordinary "greenie" metalized mylar caps from Mouser or any other supplier". source
So I looked in the internet and I found some stores.

Now - the problem: how do I choose which capacitor should I buy? I've found some stores on the internet and they have a selection of capacitors.

How do I find which one I need ?


texts:
Hi, It is the yellow cylindrical piece. It is from a led flood light.
You can see the three mains cables, two 2.2ohm resistors, a diode bridge IC, two capacitors and this yellow piece

As you see, it is burnt. But I don't know if it is a capacitor, zener, diode, fuse,.... I have lift up from the PCB. And I think it is connected between ground and a resistor. But with these 2.2ohm resistor, continuity tester is not good.

Thanks for your help.


texts:
Problem:
Powercycle microcontroller when it stops transmitting a signal (heartbeat)

Question:
What device can I use to detect the signal and send an output signal? I am looking for something small as this devices function is very simplistic. (another microcontroller? timer? etc...)


texts: Why Gain-Bandwidth Product of devices having a simple one-pole frequency response is constant?

texts:
I was reading wikipedia page of Gain-Bandwidth Product and got struck at one particular statement.

  For devices such as operational amplifiers that are designed to have a simple one-pole frequency response, the gain–bandwidth product is nearly independent of the gain at which it is measured; in such devices the gain–bandwidth product will also be equal to the unity-gain bandwidth of the amplifier (the bandwidth within which the amplifier gain is at least 1).

I am unable to understand why only one-pole frequency response devices can have constant Gain-Bandwidth Product? Why can't a device with two pole
 have constant gain-bandwidth product? Can someone give me mathematical and intuitive explanation?

In the above picture, after looking at frequency response of an op-amp, it looks like it have two-poles rather than one-pole.

Also, the gain curve (with orange pen) is of op-amp with negative feedback. Does it mean negative feedback just moves the location of poles farther (away from each other) and hence, bandwidth is increased at expense of gain?


texts: Choosing the right Over-Voltage protection circuit

texts:
TLDR :
Ideal supply voltage of a device is 12v DC (labeled near jack).
User may mistakenly provide anything from 3 to 24 DC (or maybe 220v AC).
how to protect the circuit against Over-Voltage ?
how to turn off all the circuit (at least mCU) in case of Under-Voltage (less than 12v)?
I'm trying to come up with a protection on the power supply of a circuit.
the input voltage is supposed to be 12v DC. (which will be provided by the product end user through a 5mm power jack). An internal regulator provides 5v for Microchips and other ICs, also the input 12v is needed for some other components.
the whole device should be protected against OV if mistakenly a voltage higher than the required 12v is provided. (eg. 24v DC, or even 220v AC from mains).
these are all the OV protection methods I know so far. which one is a better choice? :

A few Zeners (with different Vz ratings) cascaded to regulate the input voltage in few steps.
Zener + Darlington BJTs
Common DC-DC buck converter ICs
Crowbar
Varistors
Two NPN transistors in common base (regulates to Max EB voltage)
Zener + Fuse combo

and for Under-Voltage protection I have no idea. (mCU off if supplied V < 12v)


texts:
Im testing a 3 phase BDLC motor. I have a MCU which takes the position sensors (3 Hall-effect based ones) state and drives the adequate transistors in a full bridge so the motor can spin. The high side transistors of the bridge are PWM modulated.
So far, the motor spins, but I've noticed a couple of things that seems abnormal:
If I increase the DC link voltage (is a regulable lab suppply) the motor spins faster, but the current also increases. Why isn't the increased BEMF preventing the current from ramping? The same happens when I keep the DC link voltage constant and increase the duty cycle.
The motor has no mechanical load attached, but overheats when increasing speed by any of the previous methods. This indicates that not all the excess electric power is being converted to mechanical power. What could be the cause of this?

If you need any info about the motor or the driver, I will gladly post it.

I'm using an IGBT bridge. The drivers are IR2110, optoisolated from the MCU.
MCU decodes sensor input and outputs which of the transistors should be on. The logic gates are connected between the MCU outputs and the opto inputs and serve 2 purposes:
Modulate the high side gate signals with the only PWM signal, and modulate the low side gate signals in such a way that the loading of the bootstrap capacitor is ensured.
Just to clarify the latter, lets suppose that Q1 and Q4 should be on. Q4 is drived on for the duration of this step. Q1 is on and Q2 is off when the PWM signal is high. Q1 is off and Q2 is on when PWM is low. This gives the bootstrap capacitor some extra juice.

About the motor specs, its a Maxon 351144.
Its nominal voltage is 36 V. I've tested with as much as 20 V and less than 50 % duty cycle. Could this be a reason for the high current?
Nominal speed: 60 kRPM.
No load current: 240 mA.
When tested with 10 V and D=35%, it reaches about 6000 RPM, but my supply shows a current of about 0.9 A in the DC link.

Update: revisiting my study of the motor, I've found a problem with the stepping sequence I was using. The following picture shows the position sensor codes and the possible stator field directions.

In the previous firmware, the MCU was making these combinations:
010 -> A
011 -> B
001 -> C
101 -> D
100 -> E
110 -> F
The stator field was indeed dragging the rotor, but the angle was less than 90°. As far as I know, this is not the most efficient way to make the motor spin.
I changed the stepping sequence to:
010 -> B
011 -> C
001 -> D
101 -> E
100 -> F
110 -> A
so that the angle between the stator field and the rotor is closer to 90°.
Made a test, again DClink= 10 V, D=0.39.
Speed is about 6780 RPM and the supply reports a current of 0.39 A. Current is still high for my liking, but a far cry from the 0.9 A of before. Motor gets a tad warm, but not hot like before.

Update 2:
I revised the mcu code and took a fsm like aproach. Current went down about 100 mA. This indicates that I had a problem with cross conduction indeed.
Moral of the story: don't try to program a mcu as if you were configurating a fpga. You could fire a transistor before turning off the other in the same leg.
However, the thing that made a more significant difference was putting some inductors in series with the motor. For some reason, motor may overheat if the current gets discontinue. As the motor winding inductance is so low, some extra inductance is needed to reduce ripple and stay in continous conduction mode.
Still don't have a supply to test with nominal voltage, but at 20 V and fpwm=61 kHz the motor takes as much as 200 mA (at D=100% and ~40 kRPM) with minimal heating.
Thanks all for the help! I'll try to post some scope traces whenever I get to use the lab scope.


texts: Character/Numeric TN LCD too Dim with a Head on View as Apposed to a Side View

texts:
I am using an LCD-S2X1C50TR and direct driving it with a PSoC 4200 Microcontroller. I was testing my circuit by viewing the LCD at an angle and it looked fine. Until I put my eyes directly above it, do I notice that the contrast is terrible and difficult to read.

Things I Noticed: Bringing up the supply voltage from 3V to ~4V obviously made it better, but I was curious on why it's behaving this way. The device is rated 3V~5V on DigiKey, yet at 3V, it's only visible with a side view.

Edit: I suppose DigiKey just screwed me over. Upon looking at it with other suppliers, they state a 5V supply voltage and nothing less. There was a revision to the LCD made by the company that Digikey didn't happen to update on their end. Lesson learned.


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I want my Arduino project to listen to the ambient music and sync its light show output to the beat.

It seems that doing BPM detection properly is fiendishly difficult in software, but if your music is sufficiently doofy in nature and you use a little bit of hardware you can cheat and get away with it.

So my plan is to hook a mic/opamp breakout board to a simple 1st order passive low-pass filter and sample the input on an interrupt every 5ms or so. Audacity tells me a bass beat is around 15ms long, so every 5ms should be plenty to make sure I don't, er, "miss a beat".

If my low-pass'd sample is over a volume threshold, I'll record the time since the last beat, do some kind of weighted average calculation over the past few samples and that will allow me to predict how many ms until the next beat (some other software trickery might be necessary to account for bass drops and breakbeats.)

Firstly, do I have roughly the right idea?

Secondly, can anyone tell me what order-of-magnitude values I'll need for the resistor and capacitor? I figure I want my cutoff frequency to be something like 500-1000Hz. I also gather the resistance of the rest of my circuit counts but I'm not sure where to measure that resistance across. A little fiddling with this tool gives me answers that look reasonable (500Hz = 330Ω/1uF) but I don't know enough to really know.

An example schematic showing where I measure the resistance of the existing circuit and where the low pass filter goes in the context of the rest would be exceedingly helpful.


texts:
I was going through the documentation of TPMS sensor FXTH87 and I am trying to understand better how the low frequency receiver works.
Here is a scheeme of it :

I understand that the incomming signal is modulated, and that we have to get rid of the carrier and so to get just the envelope, we use a rectifier. But why are they 4 rectifiers?

As I understand it, the incoming signal goes trough Amp1 and then there is a buffer (why? to keep the signal intact?), then this signal from one side is rectified and on the other side it goes into a second amplifier (Amp2) and then a second buffer (why?),...

The only way I can understand it is that the signal is rectified 3 different times and summed and averaged to minimize the error. This seems weird since the signal rectified by the second rectifier seems to be signal*Amp1*Amp2 and the signal rectified by the 3rd rectifier seems to be signal*Amp1*Amp2*Amp3.

Also why is the signal clamped at the beginning? Is it this operation that they mean(see image below)?

As for what is within the yellow box I am quite lost. In the data-sheet it says you can select 2 threshold for the detection of the carrier: a high sensitivity and a low sensitivity.
It seems for the first sensitivity, the incoming signal in the yellow box will be the one after buff1 and for the other sensitivity, it will be the signal after the buff2. I guess if we select the low sensitivity, they will amplify the signal just once and take the output right at buff1. If we select high sensitivity, it means we want to be able to detect weaker signals so we amplify the signal once more before going into the carrier detector, is that the idea? What is the small arrow that looks like a current source?

Also, why is the entry of the Logic Block 2 is 129KHz? If something, it should be 125KHz in my opinion because this is the frequency of the carrier. Why is this frequency needed to decode the data? Are we somehow mixing the 2 frequencies?

One last thing : 125KHz is a low frequency, it has a wave-length of 2.4km, so as I understand it, we are not transmitting electro-magnetic wave here but we are just modulating the magnetic field. Is that correct?
The receiver has some tune circuit that resonate with the magnetic field produced by the tranceiver and this is how we get the data?

Thanks for your help and please bear with me, I don't know much about electronics, I just like to learn it.


texts:
I help organize a robotics competition in my home town. For the past 16 years, we provided each team with two 12v battery powered drill. They were cheap, easy to find and provided us with 4 batteries, two chargers and two motors. The battery chemistry was NiCd and provided us with two easy access port.

They shorted them, they depleted them, they beat them up to death and nothing spectacular ever happened. Only one time did one basically inflated.

However, NiCd 12v drills aren't available anymore. The industry defacto standard is now 12v Lipo or 18v Lipo. From my understanding, Lipo are much more tricky to use in term of charge, discharge, c rate etc..Furthermore, it gives access to all the intermediary cells on the battery connection header.

With that in mind, my questions are:

Am I right to assume that those batteries are more dangerous to use by error prone teenagers?
Are there any way to mitigate any risk?
Bonus: what kind of chemistry would you recommend instead? I know I can't ask for a specific product suggestion, but having a general idea of what chemistries are safe would be really helpful.


texts: How to identify Self Complementing Code?

texts:
Given that part of a self complementing code series looks like:

Base 6   | Code
---------+-------
0        | 000
1        |
2        | 010
3        |
4        | 110
5        |

I am supposed to fill up what code will represent the Base 6 digits on the left. How should I go about doing that? For starters, how come 4 is 110?

Also, I am asked what codes are unused? isit 6 & 7?

* Sorry if I got my tags wrong


texts: Battery Protection + 3.3V regulation circuit - Weird Issues

texts:
I just got one of my PCBs back which is designed to work with a 3.7V single-cell LiPo pouch.

The battery is currently at 3.88V

I'm using a DWO1-G battery protection IC combined with an FS8205 dual N-channel FET IC.
The output of this feeds into a HT7333 3.3V regulation IC.

I'm having some very weird issues. After plugging the battery in, the 3.3V rail is at about 580-600mV.

Now, if I take my multimeter and use the continuity testing mode and check to see if the pins of the FS8205 are connected to the right place (battery still plugged in), the 3.3V rail magically comes online and my entire circuit works (another 5V rail dependant on this starts working too).

Now if I go back and do continuity testing on the pins of the FS8205 (again battery plugged in), all the pins of the FS8205 appear to be shorted together.

What is going on? I replaced the FS8205 and same issue happened again. Could it possibly be due to the DW01-G? I triple checked all footprints.

TLDR: Putting my multimeter and poking around at the FS8205 makes my circuit output stable 3.3V as I wanted. Why?

UPDATE: If I short OD and CS of my DWO1-G IC, it fixes everything. But I have to do this everytime battery is re-plugged. Why?


texts: How to ensure proper power on reset in 1-Wire parasiticly supplied MCU?

texts:
To follow up and enhance the question on powering MCU with parasitc 1-Wire interface.

How to ensure proper power on reset of MCU in such situation?

For example this two standard method of generating power on reset may fail:

a) resistor/capacitor delay generated reset -> during power rump up, for extensive period of time data line can be low (for example due to data transmission) or pulled up only by significant resistance. This may slow MCU local supply rise time to the level that will render RC delay useless.

b) global, board level reset may not work as most probably will be removed before local MCU supply will stabilize as the "master" side of 1-wire will provide power only after reset is removed (not to mention that routing reset line defy point of using 1-Wire interface)?

What kind of precautions needs to be taken in such situations? Should MCU be equipped with brownout detection? Is that enough?


texts: Is there a professional field/classification for people who do test-engineering?

texts:
Through my career so far, I have always done work involving developing software to test electronics. This has involved writing diagnostics in embedded C/C++ for ARM controller, and even such high level stuff as writing C# code to test devices connected by RS-232, USB, and Ethernet. However, in every case it always revolved around electrical-engineering. Or, developing software for test/instrumentation of electrically-engineered products. Most commonly some sort of test/instrumentation equipment needing automated tests developed, and data/result logging capabilities. I have known quite a few of these types of engineers, but we really have no idea how to describe what we actually do.

Is there a professional classification for this kind of work? Are there any known groups or communities for this kind of engineering work?


texts: Why does a micro-controller pin use push pull when configured as an output?

texts:
What is the main reason some micro-controllers form a push-pull topology when set as an output pin?

My only guess is not to load the pin. But I couldn't find enough information about the reasons. What are the benefits of push pull output here?


texts:
I am using the BQ24075 battery charger IC (datasheet here). If I am reading the datasheet correctly, on page 6 it says that the absolute maximum sink current for the CHG output pin is 15mA. I require this pin to sink at least 40mA so I assume I will need to use a P-channel MOSFET whose gate is controlled by the CHG pin.

The circuit I am considering resembles the following:

simulate this circuit – Schematic created using CircuitLab

When the device is not charging, I expect CHG to be high impedance. When the device is charging, CHG will be pulled to GND which will switch the MOSFET on and allow current to flow into the load. Please ignore the load resistor, I have placed it there only for visual reference.

From reading other posts that concern the gate resistor, it appears as though having a large (>100Ω) resistor may cause a significant delay switching the MOSFET on. I am not too concerned with the delay, but are there other concerns with using this resistor? Could I increase the value so that less current is used when the CHG pin is pulled to GND? Finally, would this circuit work correctly as I have described it?


texts:
hello im studying the differential amplifier from Sedra Smith and i have problem with the ac mode when the signal is differential (vid/2 and -vid/2)
I know that in Nmos transistor the current flows form drain to source so I dont understand why when the imput is -vid/2 the current flows from source to drain.
the operation is different in ac? This is that i dont understand

Thanks!


texts: best way to detect if vehicle is running

texts:
The plan is to place a Raspberry Pi in a vehicle  togheter with a camera and  fully automate the startup/shutdown of the raspberry. So - what is the best way to detect that the vehicle is running?The first thing that comes into my mind is - check if the alternator outputs some voltage. The first problem appears when starting car.The alternator produces some voltage. This can be solved with some electronics (RPi power controller RPipc), to give power to the raspberry after 20 seconds when the alternator starts producing some voltage.

The second problem is shutting down raspberry. Again - RPipc can monitor alternator output and if alternator is not producing any output (or below some voltage), then send a signal to  raspberry GPIO and then the script stops all apps and shuts down raspberry pi.After one minute (some time) RPipc turns off power to the raspberry pi.

Power to raspberry pi can be provided via some relay witch is controlled by RPipc.

At this moment i do not plan to place some ODB2 tool to vehicle and attach it to raspberry pi.  And my car ODB connector is under a cover in the front of the center console:  If i want to permanently add the ODB diagnostics tool, i am going to need to solder another connector.

EDIT:
Also RPipc must wake up after it receives a signal from the alternator and cut power when the vehicle is turned off. But my question is about how to detect if the vehicle is turned on (engine is running).

EDIT 2: Here is schematics for voltage feeder


texts:
I have a USB webcam and a WiFi module which it can convert Serial data to WiFi and vice versa.

The question is can I simply convert the data coming from the webcam to serial with a USB to Serial IC (like FT232R ) and then hand it over to my WiFi Module?


texts:
I have this problem with a source transformation sum that I can't find the answer to. What do I do after these steps?

The question:

My solutions:

Can it be as simple as algaebric addition of the voltage sources? if so, how do i take the v.s. in the right into account?


texts: Resonant wireless charging with really low efficiency, even when coils are in touch

texts:
I am working on a new project which uses wireless power transfer.

I know that wireless charging in general is not so effective but my circuit is extremely not effective. Can I ask you for some advice?

I attached a picture of my circuit:

Basically it is just modified Royer oscillator, supplied by 5V DC and using logic level transistor to turn on even with 5V.

This circuit has load 47 ohms however later I would like to connect and charge a battery. As a coil I use a planar coil with litz wire with diameter 40mm with resistance less than 0,1 Ohm.

I also attached a picture of my circuit on breadboard.  I am limited with frequency which should be 150 kHz in maximum.

I have already tried plenty of experiments but still dont have a solution. When the receiver coil is placed far from transmitter circuit so no load attached, transmitter takes 5V and something around 150-200 mA.  When I am move the transmitter coil closer to the receiver coil, at 1 cm distance current flows through 47 ohm load (around 50 mA) but source gives to transmitter almost 600 mA.

I also noticed that when coils are in touch source gives almost 1 A and chokes and transistor heat up rapidly and transmission doesn't work correctly. It seems that transistors don't fully open.  I have plenty of coils and I have not reached higher efficiency with any of configurations more than 15 percent.

Maybe the Royer oscillator is not a good candidate for such a circuit, but I really like it for the simplicity and few components, but I have no idea how to increase efficiency.


texts: Series resistors in smps after Bridge rectifier

texts: what's the use of series resistor R2 in smps circuit .won't it work if I use a single resistor with high Resistance & voltage rating?.


texts: Which is better for an adjustable stable reference voltage output?

texts:
I have two methods of achieving this and am trying to decide which one will be a better option for a stable output. The supply voltage is a linear regulator output, so it is pretty much constant.
Option 1: Using op-amp with voltage divider using 1v Zener diode (TZMC1V0-GS08)

Option 2: Using op-amp with voltage divider circuit

The adjustable range should be at max +/-2V, at this voltage having an accuracy of 0.01% is much preferred
The output in both cases will be connected to one of OPA875 inputs which has an internal Av=+2. I guess in this case, the output current demands are negligible
Let me know if you have any questions
thanks


texts:
i was looking for the Energy conversion efficiency of my circuit in Ltspice, but i find out that my Transformers is giving me strange power values i mean with K = 1 the P1 should be equel to P2 but in my case P2 is is way too small , i get equality 90% only if get rid of the Flyback diode, can you please help me understand the reason behind this

simulate this circuit – Schematic created using CircuitLab


texts: Passing <5V through bus of tri-state transceiver

texts:
I am following a schematic which implements a basic 8-bit register. The schematic is pictured below:

According to the datasheet of the 74LS173 chip, The high-level output voltage is 2.4V with testing conditions assuming the minimum input voltage (although my case Vcc is 5V). The current configuration is set to output ~2.4V at each output pin on the 74LS173. I can confirm that the output is indeed ~2.4V. It appears that this chip is functioning perfectly well.

The chip receiving this 2.4V potential is the SN74HC245. This chip is also fed 5V Vcc. The datasheet only states two input states (high + low) high being >3.15V at 4.5V Vcc and low being <1.35V at 4.5V Vcc. It is wired such that Ax is the input and Bx is the output. When I provide 5V to an input, I have 5V present at the cooresponding output. This is as we would expect. However, I need the 2.4V from the 74LS173 output to be present at the output of the 74LS245. In my head, I assume that I cannot simply pass 2V from the input of the transceiver since this is neither high or low. However, in the above schematic 2V is present in his outputs of the transceiver.

This is demonstrated here: https://youtu.be/9WE3Obdjtv0?t=193

In my testing, when 2.4V is present at any A input, it does not exist at the corresponding B output. Whereas the same test with 5V input is indeed present at the output.
In the datasheet for the SN74HC245 it appears that lowering the supply voltage lowers the minimum high-level input voltage, but in his case this was not necessary. How is this possible?


texts: What happens in the Arduino power supply schematic?

texts:
I was just looking at the power supply part of the Arduino Uno, but I am a bit confused:

1) Why the opamp LMV358 with VIN as input (USA)?

2) Why the opamp LMV358 with SCK as input?

3) Why an LP2985 to convert 5V into 3V3?

Here is a screenshot of the schematic.

Thanks!


texts: What would cause an erratic voltage on my DC bus when my power inverter is under a load?

texts:
Using a Tripp Lite PV2400FC inverter, rated for 24VDC input and 120VAC output at 2400 Watts;
We have two 8D 1050 CCA batteries;
The engine alternator is rated for 280 amp at 27.2 volt;
We are supplying the inverter with 2/0 cable.

Note:  Conditions noted will be with the engine running.
When the inverter is powered on with loads under ~1000 Watts the DC bus voltage is regulated at 27.2 volts.
When the inverter is loaded with ~1000 Watts or more the DC bus voltage becomes erratic and varies between 24 volts and 32 volts.  What could be causing this?


texts: Is it possible to speed up Battery simulations with power converters in Simulink?

texts:
I am facing a huge problem with real-time analysis of a PCS simulation. I want to simulate a power converter system, which can be used as a power converter. I have to do an accelerated simulation with a Battery. discharged into a resistor for example, I can simulate multiple times for a while in seconds and see the behavior of loading and unloading it, but the same did not happen when switched converters. To simulate 1h (3600s) for example, it would take a long time, so I can not see the discharge dynamics (SoC variation) of the battery, because if the simulation time is 1s what the battery sees is a current request that lasted 1 second only. How do I make this simulation "more real"?

Update (Showing my model)

So my model consists in a bidirectional boost converter with a battery as a LVS. Into the subsystem "Controlador" within the "Controlador" block there are only 2 PI controllers and one PWM.

Then again describing my problem: If I just simulate the Battery pack with a controlled current source, I can simulate 21600 s (the equivalent of 6 hours) in just a few seconds in real life.

Take a look ate this simulation

12.8 V, 40 Ah, Lithium-Ion (LiFePO4) Battery Aging Model (1000 h Simulation)

This is a 1000h simulation that takes no more than a few seconds. So, what I'm trying to do is discharge this battery, and for that I need at least 3600s simulation, but in my model takes 3600s (more or a little bit less) in real life.

Ps.: The switching frequency is \$25kHz\$


texts: Fluctuating ADC readings upon changing power source

texts:
I used the following circuit to power and measure my pressure transmitter (4-20ma) sensor and the microcontroller, when the charger and battery are connected at the same time or when i disconnect the battery i get a fluctuating readings from the connected ADC (Arduino or Raspberrypi), i only get a stable readings when the battery is the only power source.

Would you please explain the possible causes of this issue, and what should i do to have uninterrupted power source without affecting the measured values.

Thanks


texts:
I have a hardware structure (described in logic diagram consisting of adders and multipliers) that is extremely regular, i.e., one small hardware is repeated again and again in the structure with regular pattern of interconnects. for example, see the schematic below.

The hardware on the right is formed using multiple copies of the small hardware element on the left.
Now, suppose I have another structure that has the same number of Z-elements (in the above example image) but it doesn't follow any regular pattern of interconnects between different layers, i.e., the interconnections between Layer 1 and 2 are random. My question is which of these hardware will be better (in terms of power efficiency, area or any other respect) or they will both be identical in terms of performance (power, area etc.) ? Please answer both with an FPGA- and ASIC-based implementation platform in mind. Any references are appreciated.


texts: Latching Push Button High Side Power Switch

texts:
I'm a beginner trying to design a long-push to turn off and short push to turn on push button switch. I've managed to find this design but when put into use in a 3.3V system, it does not seem to work. Every time I turn the power off it will just spring back into the power on state after a few seconds. Can someone help with how I can solve this problem?
3V3_SWITCH is coming from the power supply and +3V3 is the power leaving this switching circuit
I understand that the 10uF cap and the 330k res form the fundamental RC delay circuit and the PMOS is the main switch while the NMOS is the latch to keep the system on. However, since I am not sure about how the rest work, I am unable to come up with a logical solution to this problem.
Note:

I found out that either C35 or C37 starts discharging after some time, could be because of the NMOS turning off
when an oscilloscope is plugged into the node between C36 and R37 with reference to ground, the switching circuit seems to work (doesn't spring back into power on), so I'm guessing it has to do with the Resistance of R37 or R36 being insufficient?


texts: Why are BJTs common in output stages of power amplifiers?

texts:
From my understanding, the role of the output stage is to decrease the output impedance to almost 0. For that, MOSFETs seem better suited since they've got way lower \$R_{ds}\$.

Yet I see quite often BJTs as buffer in discrete design, often in a Darlington configuration to increase input impedance, while only one MOSFETs would have a high enough input impedance.

My thoughts were that it was either cheaper or simpler. Power BJTs are indeed a bit cheaper than power MOSFETs, and it seems to me that it is simpler to make a relatively linear buffer with a BJT emitter follower, while a MOSFET source follower may require some feedback.


texts:
I'm studying this app. note on frequency discrimination method to measure phase noise.

In page 35, appendix A, there are these equations:

The input to the transfer function is \$\Delta f\$ and output is \$\Delta V\$. What happened to the

\[
\sin\left[2 \pi\; f_m \left(t - \frac{\tau_d}{2} \right) \right]
\]

term when writing the equation for delta V?

Sorry if it is too obvious. I just could not see why.


texts: Which battery to use to charge from 12v solar and supply raspberry pi

texts:
I'd like to run my raspberry pi via solar energy. I have a 12v 20w solar panel with the following charge controller:

https://www.amazon.co.uk/gp/product/B0197ZNWLM/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

The following 5v regulator:

https://www.amazon.co.uk/gp/product/B00RGK5G3I/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

My problem is I don't know what kind of battery to use for this set up.

Can anyone suggest and explain the kind of battery that can supply power to the raspberry pi and at the same time be charged from the solar charge controller?

Many thanks,

Paul


texts: Is transconductance concept more important for FETs than in BJTs

texts:
In some texts I encounter they mention transconductance when it comes to FETs not BJTs. I have seen myself many texts and skimmed through them, the word transconductance does not appear until FETs. Before they teach BJTs and they use hfe and other parameters but not gm.

For BJTs they do not necessarily menton transconductance, instead they use hfe i.e forward current transfer ratio.

Having said that, I also saw some tutorials which use the transconductance when they teach BJTs.

Could there be a reason to employ transconductance concept more for FETs than in BJTs?


texts:
Following image is from a measurement I did with a spectrum analyzer, configured to save the highest peaks.

The channel center is at 2.402 GHz and has a BW of 2MHz (2.401 - 2.403 GHz).
The signal modulation is GFSK. I do know that, depending on the data, for 0 the offset from the center frequency is -f_o and for 1 it's +f_o (frequency_offset).

Am I assuming right, that the peaks @ 2.401 and 2.403 are transmitted 0's and 1's?


texts: Board Design for High Impact Environments

texts:
I'm looking to design a PCB that can reliably survive constant impact. The board will be rigidly mounted to an enclosure that will protect the board from actually hitting anything. The nature of the impact would be similar to a bowling ball, or a hammer head - not what I would consider vibration, but frequent hits from multiple directions.

As part of the device functionality, I want to measure the acceleration of the board, so dampening the impact in any way is not preferable. I don't have any measured acceleration values (G's) to provide as a baseline, and I don't really have any experience in this area. As such, I have a few closely related generic questions:

What is the most force that would be OK on a board with no impact hardening measures taken? (Am I worrying too much about a non-issue?)
Are there any design practices that should be followed for the PCB?
What are the weak points in a design that lead to mechanical failure?
Are there parts that should be avoided for a more robust design?
At what force levels should I start worrying about the safety of the parts themselves?


texts: How do you bring up the equations for this Op-Amp numerical question?

texts: How do you make the KCL/KVL equations for this circuit? Does input impedance means calculating overall circuit impedance?


texts: Why is the signal always entered into minus port in inverting op-amp?

texts:
I think output voltage value is same either if I connect input signal into + port or if I connect input signal into - port. The reason why I am thinking like this is come from

$$
V_{out} = -\frac{R_f}{R_{in}} V_-.
$$

I understand the right figure's output is surely -10V because
$$
V_{out} = -\frac{R_f}{R_{in}} V_{in} = -\frac{10000}{1000}{1V} = -10V
$$

However, the left figure's is..... I don't know.

Why does all textbook or other documents use the right circuit instead of left one?


texts: Capacitors -> Storing 500 Joules in a capacitor with a simple 9 volt battery

texts:
I am a newbie to not only this forum, but electrical hobby(ing) also.

I need 500 Joules within a few milliseconds from a capacitance. I plan to make this capacitance at "home". I plan on using a standard 9V (18KJ) battery to charge this up. What would be a suitible dielectic, and how would I go about doing this?

[EDIT] I want all 500J in a few miliseconds at 200V