texts: Referring to my previous post. I have successfully generated 500V. The problem I am facing an issue. MOSFET I am using for switching is FQB34N20LTM. The MOSFET is burning badly. The snap of drain pulse is attached below. I have attached a good heatsink having fins as well but temperature never stops. Previously I made the prototype using breadboard and my circuit was cool, now I have made the PCB and it is burning. Please suggest me what should I do? Thanks in advance.


texts: How to know if a diode is Schottky or power Schottky?

texts: I bought a diode for a circuit but the guy who sells components asked me if I want Schottky or power Schottky. I need to buy SB2040 but I cannot figure out what type it is.


texts: Is it possible to digitize small signal with large noise?

texts:
I have a small signal, e.g. ~100 uV in a band of interest of 0.1 - 30.0 Hz
This signal is accompnied with a huge noise of 50 Hz ~100V of amplitude.

ADC's input range is 1V.

Is it possible to digitize the small signal without the use of analog input filters to fiter 50Hz noise?

I may place an input amplifier with K = 10000. So, my small signal will be in the range of ADC's input.
Input amplifier will clamp 50 Hz noise to acceptable input levels of ADC and introduce harmonics with frequencies 50 Hz and higher.
Then I will filter these harmonics with a digital filter.


texts:
I am a third year student in Electrical Engineering, and I would like to get into Control systems. I was reading about the job ads and I noticed that I need to know PLC and HMI.
I don't know if they teach PLC and HMI in school, so I would like to get ahead of my career and start learning them as I have so much free time right now. does anyone know where I can start ? I want to self learn them, any insights on this will be greatly appreciated.


texts: Ethernet: how important is the magnetics topology?

texts:
I have some Ethernet issues with a set of boards (6/10 are bad). They're possibly just assembly house mistakes... but I'm very concerned about my magnetics jack.

I could have sworn I saw a example schematic with my jack's topology used with my PHY before, but I can't find it. The PHY's datasheet and suggested magnetics jacks are all identical in topology, and very different than what I have.

I'm using a SMSC LAN8720AI PHY, with a Bel SI-52003-F magnetics jack.  The transformer ratios on my jack vs. a suggested jack for this PHY like the SI-60152-F are the same (1:1).  The inductance is the same, 350uH. However, the choke on mine is on the circuit side, not network side. Also, while the TLA has four 75 ohm resistors from taps tied to a single 1nF/2kV cap, mine has an extra set of 1nF caps between the taps and the 75 ohm resistors.

The main difference is that my jack is a POE jack, and I thought I found an example that used one exactly like it. So, the topology is obviously different just because of that feature.

At the moment, I have 4 good boards, 1 'sometimes' board, and 5 boards that just blink a LED at 11.68Hz representing some error that no datasheet explains.

How important is this? Of course there's no other jack with that footprint.

EDIT

I added some detail on the magnetics jacks above. I was just recommended the SI-60152-F, so I'll compare to that one. Of course like all the other recommendations... it also has no stock at anyone on FindChips.

LATE EDIT

It turns out my problem was the crystal layout that fed the Ethernet PLL.  On the respin, I went with a more standard non-POE jack.


texts:
I'm thinking of something akin to transforming clothes into LED displays. (Not quite, but close enough.) Lots and lots of small beads (and fewer larger beads) embedded into the fabric and connected with wires.

Google gives me lots of images for "LED clothes", but the problem is, they all look like costumes that require very delicate handling. What I want to achieve is something you could, say, go to bed in regularly, and have it still working after months of such abuse. The fabric itself should take most of the stress, but it still sounds like it would be rough on the wires.

Is there any kind of wire flexible and durable enough to survive that?


texts:
I have a question as follows. This is not a homework question I just need to clarify my doubt on how this modulation index is defined.

Suppose a 2kHz audio tone having 2V amplitude is to be amplitude modulated on a carrier \$x_c(t) = 5\cos(6\pi 10^5t)\$ with a modulation index of 0.8. For the resulting AM signal

Derive the mathematical expression
$$x(t) = A_c[1+\mu x_m(t)]\cos(\omega_c t)$$
$$x(t) = 5[1 + \frac{0.8 * 2}{5}x_m(t)]\cos(2\pi*3 *10^{5}t)$$

is this correct? Isn't modulation index made from \$\frac{2}{5}\$ so do I have to use it like this?

$$x(t) = 5[1 + (0.8 * 2)x_m(t)]\cos(2\pi*3 *10^{5}t)$$

I carried on with the first formula

Sketch the frequency spectrum

I calculated the amplitudes as follows
Carrier Amplitude = \$\frac{A_c}{2}\$
Side band amplitude = \$\frac{\mu A_c a}{4}\$ where a = 2

Find the bandwidth

\$2 \times f_m\$ = 4 kHz
Find the power of the carrier frequency component

\$\frac{A_c^2}{2} = \frac{5^2}{2}\$ = 12.5 W

Express the total sideband power as a ratio to the carrier power

\$(A_c[1+\mu x_m(t)]\cos(\omega_c t))^2\$ simplifies into \$\frac{A_c^2[1+\mu ^2 x_m^2(t)]}{2}\$

so the carrier power is \$\frac{A_c^2}{2}\$ and total sideband power is \$\frac{A_c^2\mu^2x_m^2(t)}{2}\$

so as a ratio to the carrier power, it is \$\mu^2x_m^2(t)\$ which simplifies as \$\frac{2^2*0.8^2}{2}\$ (Because amplitude of modulating signal is 2V)

Is this assumption correct?


texts: Will this op-amp circuit work to convert differential audio into single-ended input for the bluetooth transmitter module?

texts:
I'm making a bluetooth audio transmitter based on FSC-BT802 module that needs to take an amplified Mono 3W 5V (from -10V to +10V) differential audio as Line-In input. So I need a differential to single-ended converter and a line level attenuator circuit. Then it will connect to both Left and Right MIC inputs of the bluetooth module. So I need to attenuate 5V to 500mV-1V input and convert it to single-ended. I already tried a direct differential audio input to MIC pins with those 4.7uF capacitors and input voltage attenuator resistors but always got noise in the output sound in the other bluetooth audio receiver. And single-ended input worked much better, without noise. The whole bluetooth audio transmitter module power supply will be a Li-Po 3.7V battery (3-4.2 Volts). Op-amps I found: INA134, SSM2141, ADA4807-1, TL071... which one will suit my application better? Or maybe there are better op-amps?
Am I understanding it right? Any suggestions how to improve the audio input circuit? Thanks!
FSC-BT802 module Datasheet:
FSC-BT802 module Datasheet PDF
Toy sound board speaker amplifier (my differential audio 5V 3W Mono output source):
MAX98357A
And this amplifier (audio output) working schematic:

My current bluetooth module audio input schematic:

I also tried direct differential input, but always got white noise in the sound on background:

And I even tried using just 1 of the differential audio input wires connected to both Positive Left and Right input channels and leaving the other wire not connected. The sound quality was better and less noise, but was a bit distorted with a little bit of white noise:


texts: How to decide which key was pressed on a calculator?

texts:
Hi all,

I'm trying have an arduino read key presses on my calculator. The calculator does it by pressing the keyboard membrane to the PCB and connecting two points, so each key has two of these points. I've soldered wires to two key's contact points(four wires in total), and connected the arduino's GND to the calculator's -ve.

I read the values in analog, then calculate the voltage, so I would see a change in voltage, when a key is pressed, and the key would be identified by which contact point had the v. change happens on.

Now here's what actually happens... Every contact point has a voltage change(to an equal degree, too) when either key is pressed. One and three jumps to 1.4, two and four jumps to 0.0.

There's a chance I somehow damaged the circuit, but other than that, I have no idea what I'm doing wrong...

Here's my code:

int one = A0;
int two = A1;
int three = A2;
int four = A3;

float refVolt = 5.0;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  int oneR = analogRead(one);
  int twoR = analogRead(two);
  int threeR = analogRead(three);
  int fourR = analogRead(four);

  float oneV = (oneR/1023.0)*refVolt;
  float twoV = (twoR/1023.0)*refVolt;
  float threeV = (threeR/1023.0)*refVolt;
  float fourV = (fourR/1023.0)*refVolt;

  Serial.println("One: "+(String)oneV+" - Two: "+(String)twoV+" - Three: "+(String)threeV+" - Four: "+(String)fourV);

  delay(100);

}

PCB with the wired points marked:

If this is how the whole thing should work, is there any way to read and decide which key was pressed?
If my way should work, what am I doing wrong, and how can I fix it?

Please share any thoughts, solutions, ideas! Thanks in advance!


texts: Design decisions about computational hardware for small mechatronics project

texts:
I've recently started learning electronics/mechatronics. As part of my studies, I've been reading about devices such as RaspberryPi, Arduino, etc, and I'm interested in experimenting with such devices.
I have what would, I guess, be considered a "design" question. Let's say I wanted to undertake a small robotics project. Furthermore, let's assume that I wanted this small project to just be something that remains connected (via usb, say) to a computer. In terms of the electronics involved here, how would I go about making design decisions about whether such a device would require a microcontroller (such as Arduino), a self-contained computer (such as Raspberry Pi), or whether no such separate computational hardware is required, since it is connected to the computer (and the computer can do all the computational stuff itself)? Specifically, what I'm actually asking is a beginner technical question: Does such a robotic device, as described, require having some separate, additional computational device, such as an Arduino or Raspberry Pi, in order to operate (since this might be required to interface with the computer, or something), or are such devices superfluous if it is connected directly to the computer already (that is, the computer can somehow (through the more "primitive" (for lack of a better term) circuit board elements) directly interface with, and control, the robotics device? Furthermore, if the latter is the correct answer, then is there any situation in which, despite being connected directly to the computer, that it would be a good design decision to also include one of these separate pieces of computational hardware in the device (say, for computationally intensive tasks (although, it is connected directly to the (much more powerful) computer, so I'm not sure that this would make any sense))?
I'm not sure if this would get covered later at some point in my textbooks, so I thought that I might as well ask now, just in case it never gets covered and I forget.
This probably heavily relates to "control systems" or "control engineering", but I am very new to all of this, so I'm not yet familiar with all of the specifics of hardware.
I would greatly appreciate it if people would please take the time to clarify this.


texts:
when I came to an explanation of the induced emf in the straight wire it shows that the wire starts its motion from the position where it is perpendicular to the magnetic field lines, like this:
And the equation used to measure the induced emf is (emf=Blv sin theta)
Where theta is the angle between the direction of motion and the magnetic lines. And I was wondering how the equation would be if the wire starts the motion from a position where the angle between it and the field line is less than 90, something like this:
In the figure above there are two angles: the angle between the wire and the field lines and the angle between the direction of motion and the field lines, so which angle will be involved in the equation (emf=Blv sin theta)? Or are the two angles equal each other?


texts:
So im kinda curious which this would be. I have a question to turn a Boolean expression into a logic circuit which I have no issues doing but im a little confused about this question. I will leave an image below of the expression and also the circuit I feel like it is, im just confused whether (A.B) is AND or NAND as I am not sure if the line above everything is for the + only or for the first brackets too.

The image above is how I see the circuit


texts:
I'm relatively new with Altium Designer and I'm trying to export a pcb to a STEP model in order to build a chasis in solidworks, but when I export it, there are missing parts. Let the images guide you:

The fisrt is from Altium and the second from Solidworks.
When exporting, I have tried this already:
1- Reloading every generic3D models in the pcb library.
2- Every exporting settings or options have been tried.
3- Cried a lot, nothing's changed.

Nothing on the web has helped me yet. Thank you.
\
\
EDIT#1:

I have done some changes, corrected all the errors (don't know if it is linked) but now I get this message of error:

The problem is that the unsupress button, in the view panel is geryed out... Can't do nothing but do nothing.


texts: How can I amplify a square wave signal with a mosfet?

texts:
I have a CCD camera that is triggered by an external TTL square wave.
That is each time the camera sees a rising edge on the square wave it takes a picture.
The square wave is being output from a custom microcontroller card when in capture mode.
So far I have used a oscilloscope to verify that the microcontroller card is indeed in capture mode and outputing a square wave.
I want to create a small circuit where a LED is being controlled by the square wave signal (0->5V).
That way I can instantly see if the camera is running or not.
I do not want to draw much current from the signal. I have some 2N700 mosfets. So I want to use one of these to amplify the signal.
This is what I have come up with so far:

simulate this circuit – Schematic created using CircuitLab
Should this work?
Is there some easy way (eg. change resistances, I have a wide range of resistances) to improve the design?
BTW the input impedance of my oscilloscope is 200k Ohms. Maybe the input impedance of my circuit should be in this ballpark?
I have tested the circuit with a function generator as input and it appears to work just fine.
However when I use it on the real signal it blinks as expected for a while and then get stuck in high state for a while and then blinks again. The stuck in high state is not something I expected. Not sure if this is a problem with my circuit or the software running on the custom microcontroller card.
May it suffice to drive the led directly from the signal:

simulate this circuit
This should draw 5.5 mA from the output of the microcontroller.
Would that be a problem?


texts: floating inverter output causing over circuit protection?

texts:
When I was testing the inverter circuit as shown below (it is only one phase of the inverter with three MOSFETs in parallel), there was a phenomenon that I couldn't understand.

Initially, I didn't connect the motor terminals, the inverter outputs were floating and the motor was at standstill. The DC power supply that provides power to the whole system was configured to have current limit at three times of the actual motor operating current.

Then for test purpose, I applied six-step gate driver signals based on standstill hall sensor reading (HIGH side PWM and LOW side full-on). Since the motor was not connected, the drive signal could only be one out of the six combinations. However, the DC power supply generated over-current protection.

After I connected the motor terminals and drove the motor in six-step operation, everything was fine and no over-current protection was generated.

My question is, why was there over-current (short-circuit?) when the motor terminals were not connected?

[update]
The PWM duty cycle used in both cases was the same.

[update 2]

The negative side of the inverter was connected to shunt resistors shown below and then connected to ground. Sorry for any confusion.


texts: How to measure Stepper motor current when using EasyDriver A3967?

texts: We are using EasyDriver stepper motor driver A3967 for running a stepper motor. We wanted to measure the current consumed by the motor using an oscilloscope. Can you give us some suggestions on how can we do that? I read about measuring the voltage across the sense register but I don't know whether it is the correct way? Where can we add a resistor in the circuit to measure current consumed by the motor?


texts: AVR + IEEE 802.15.4 (<1GHz) potential transceivers

texts:
I'd appreciate it if someone could offer a couple of suggestions about pairing up an AVR MCU (I'm thinking about using the MEGA162V-8PU ) to a general ISM < 1GHz (transceiver), and the ATTINY85 on the other end (with another transmitter).  Architecturally, my system is similar to an RF garage opener. There is a base station (using the MEGA162V-8PU) that has 2 sensors connecting to it. In terms of the preferred PHY protocol for the transceiver I was thinking about using the IEEE 802.15.4 (LRWPANs) as it allows for both 'peer-to-peer' and/or 'star' network designs.

I've been scouting the Internet for potential solutions/ideas. There are plenty of options out there, but I can't seem to find the right one for me. Firstly, most MCU+Rx/Tx IC solutions don't come with enough GPIO ports. This makes it hard (if not impossible) for me to use any of the ATMEL's  all-in-one options (such as the AT86RF212B) - especially for the base which needs at least 3 or 4 push buttons an LCD module, and a couple of relays. In my mind using a single-chip (MCU+Transceiver) solution would be beneficial for multiple reasons (heat, power consumption, PCB space, etc.), but I don't think there is anything available for my number of GPIO pins, correct?

For the sensor I could try to go with only an MCU + transmitter as it only has to capture data and send it back to the base (one-way communication). Has anyone designed something similar before?

Any ideas/suggestions are very much appreciated. Thanks much in advance.


texts:
What else besides an ADS1299 from TI and a 32bit microcontroller (like Teensy or Electric Imp) would I need to get an sEMG signal?

The ADS1299 is a "low-noise, 8-Channel, 24-Bit analog front-end for biopotential measurements".

So, every 2 or 3 leads (depending on the electrodes configuration) from the ADS1299, I should be able to get electromyographic data. Right?

I live in Europe so I would probably need a low-pass filter for the 50Hz range too, right? They do say it filter's most of noise out though.

This is my first time doing something like this. So be patient with me.


texts: Li-ion battery charging termination current

texts:
I have almost no experience with Li-Ion charging.

Documentation to battery is very poor, but there is an info about charging profile:

Stage 1: Constant Current 0.82 Ampere (0.2C) until Voltage reach 4.2V
Stage 2: Constant Voltage (4.2V) with decreasing current 0.82A -> 0.12A

I want to design charger for that battery. I have found several charging ICs (for instance LT3650) that fit my design pretty well, but this IC terminate charging process at 1/10 of programmed charge current. In my case: 0.82A/10 = 0.082A what is about 1.5 times lower than 0.120A in battery specification.

I confused a little with min charge current in spec, I supposed the lower current you can provide the more "fully" you charge battery.

Is it safe to continue charge Li-ion after 0.12A threshold till 0.082A (and how it could affect battery), or
is it better to use IC's with user programmed termination current
(like LTC4068-4.2) to stop charging process exactly at 0.12A?


texts: How to convert asynchronous set FlipFlop Hard macro into asynchronous reset FlipFlop?

texts: My query is, if there is a asynchronous set flop in a library but the implementation or RTL required a asynchronous reset flop, how to achieve this?


texts: I need an aerial adaptor for my 4G modem. What are the names of these types of coax connectors?

texts:
I have a 'Mifi'™ 4G modem. I ordered an external aerial for it, but the diameter of the connector is about four times the size I need. I want to buy an adaptor, but I don't know what search terms to use.

What are the names of these types of coax connectors, both on the cable and the modem? Is there a common name for the adaptor?

The coin, for size reference, is a US 'dime' (10c) and has a diameter of 18mm.


texts:
I'm planning on doing a one-off project that will need a monochrome LCD 3-4 inches wide. Unfortunately, I haven't had much luck finding what I need. Smaller screens like those salvaged from cell phones, such as the Noka 5110, and commonly used with microcontrollers are really ideal except that they are too small. I haven't had any luck searching sites like Mouser. It seems that color LCDs have mostly replaced them.

So my question is, are there any devices that would be good sources for salvaging monochrome LCDs? Cell phones, PDAs, and printers all come to mind, although I don't know if any of those fit all of my criteria. Working documentation is the most important. Many devices have nice LCDs but it isn't always possible to tell if it would be possible to get them working. Do any of you have experience working with a salvaged LCD with these qualities?

-screen width around 3-4 inches
-width:height ratio between 1:1 and 2:1
-resolution above 128x64
-matrix display, not character
-supply voltage between 3v and 5v
-can be driven by a microcontroller
-hand solderable pins or ribbons (around 0.6mm or bigger)
-datasheet or other documentation

EDIT: Rephrased question


texts:
I have a question about what looks to me like a non-minterm/maxterm minimization of a simple logical circuit. Sidenote: This seemed like the right place to ask this question, but let me know if there's a more appropriate community here on stackflow that specifically handles questions like these.
I noticed that the full adder can be decomposed into the two half adders. The logical circuit for the nth + 1 carry over bit is represented in minterm form as xy + xc + yc where x and y are the two bits being added and c is a carry over bit from a previous addition. This can be rewritten after some algebraic maniplulation as xy + (x Xor y)c. This isn't a simplification but a design choice that makes efficent use of the fact that there already exists an x XOR y implementation elsewhere in the circuit of the full adder, namely for computing the s bit. If the x Xor y element wasn't present, there'd be no logical reason (disregarding other aspects of circuit design) to replace the x or y element in this circuit with the x Xor y element.
In simple cases like these, its easy to spot these sorts of "minimizations". But for larger circuits it become very difficult to do so and since no textbook I've come across talks about this technique, I have a few questions.

What's this kind of optimization called?
Is it commonly used in industry?
If it is, how do engineers using CAD tools tell the computer to look for something like this? I mean, it seems like it would be very computationally intensive.

Thanks in advance!


texts: RTC Crystal place is exposed on the STM32F4-Discovery board. So which kind of 32.768 KHz SMD Crystals is proper for that place? Could you give a part number or a link to buy?


texts: Why am I not arriving to non-inverting amplifier equation?

texts:
I was trying to derive the non-inverting amplifier equation and I ran into some trouble deriving it.

By making the voltage between R1 and R2 VRef, I set my equation to

Vin - VRef = Vout.

Because

VRef = Vout(R1/(R1+R2)), this means

Vin - Vout(R1/(R1+R2)) = Vout.

By simplifying the equation and moving Vout to the other side of the equation, I am getting

Vin = Vout (1 + R1/(R1+R2)) which simplifies to

Vin = Vout (2*R1 + R2)/(R1+R2).

When I then move it over to the other side of the equation, I get

Vin (R1+R2)/(2*R1 +R2) = Vout

and I am stuck with an ugly fraction I can't seem to simplify or reduce. Does anyone have any advice on how to simplify this fraction to (1 + R2/R1)?


texts: Does placement (high side vs low side) of a hall effect sensor matter?

texts:
So I ran into something interesting today.

I have a hall effect sensor (L18PXXXD15) and I was attempting to measure current of a 30Vrms sine wave across a 50 ohm load. However, when I connected my hall effect on the high side, my signal dropped like 10Vrms. When I measured across the current sense pins, I noticed my missng 10Vrms was there. When I increase frequency, the drop increases and when I lower my frequency the drop decreases.

I switched it to the low side, and I'm able to get my full voltage across the laod, as expected.

Generally speaking for hall effect sensors, does placement matter ? I've only messed around with this one sensor, so I can't say if generally all hall effects are required to be low side, or whether it varies.

Is there something in the datasheet that I should look for that might indicate placement ? There was none that I saw for this particular one.


texts: Is there a bidirectional level converter IC for multiple I/O channels?

texts:
I have two digital devices to connect, both use 20 data lines but one works at 3.3V and the other at 1.8V, and most of the lines are bidirectional. The operating frequency should be at least 5 MHz. I stumbled upon this solution:

http://www.rocketnumbernine.com/2009/04/10/5v-33v-bidirectional-level-converter/

Which seems adequate (provided I make the corresponding changes for the desired voltage levels) but I don't like the fact that it needs 1 IC and 2 resistors for each data line. Does anyone know about an IC that does a similar job but has many channels (ideally 20 or near that) in a single package, or any equivalent solution to the problem?


texts: How is the solution for \$\alpha\$ and \$\beta\$ current gain of a BJT derived?

texts:
I'm just an enthusiast, and not too good at maths; I'm exploring constant current source circuits, in doing so I came across two equations for BJT current gain:

Could someone help me understand how \$\alpha\$ and \$\beta\$ are derived to the equations below:

\$\alpha=\frac{\beta}{\beta+1}\$ and \$\beta=\frac{\alpha}{1-\alpha}\$

I know that:

\$I_c=\alpha I_e\$ and \$I_c=\beta I_b\$

Any help would be much appreciated.

Thanks
Alex


texts:
I work on a industry as an intern and I'm having a trouble. Clearly there's a fault on the net, but I can't figure out which type it is since I'm having strange readings from a basic multimeter. I'm in Minas Gerais, on Brazil, where each phase have 127 V and here it's a very common practice the neutral grounded (there's no difference between the ground and neutral). So, let's go on.

When I measure each live to neutral it gives me 127 V, also does ground to neutral.

When I measure each live to ground:

A to GND: 220 V

B to GND: 0 V

C to GND: 220 V

Neutral to GND: 127 V

If we change the reference a possible voltage on conductors are as follows:

A: 127 /-120°

B: 127 /0°

C: 127 /120°

Neutral: 0

GND: 127 /0°

Anyone have an idea of what's my problem? What's the simplest/cheapest way to solve it?

Thx very much


texts:
I calculated my inductance value and current rating but I can't decide which inductance I have use. for example 10uH, max 800mA my inductance values but there is other variables.in this topic I have some questions .What type of inductance should be? Multilayer,Wirewound or Molded.what Material - Core of inductance shoul be?Ferrite or Powdered Iron? how can i choose inductance? for example i want to use step down or step up converter or LC filter? what kind of situtaion i should think?
If anyone has information about this topic i will glad.
By the way i am so sorry for my english.


texts: How can i extract transfer function an unknown nonlinear system?

texts: I am trying to do PID control for my electroservo motor system by using nichols ziegler tuning method. My system has SSI encoder output for motor feedback mechanism. I will use this knowledge for control. According to nichols ziegler method i must know transfer function of my system. But i can not find its equation exactly. So how can i extract its transfer function? I need a methodology for this. Can i extract T.F. by using Matlab/Simulink or LAbview?


texts: What is the energy efficiency between FM radio tower broadcasting over an area vs point to point streaming via Internet?

texts:
Doing some research, it seems that an FM radio tower in a densely popoulated area can maximally transmit about 50kW of power.  If you assume a certain amount of people tuning into the station, is that more efficient than the same amount of people streaming the radio over the internet?

Multicast over internet is probably more efficient, but I'm not sure if most internet streaming of radio is done through multicast.


texts: LM317 Voltage Regulator multiple output where one is 12v constant and adjustable

texts: Is it possible to output LM317 in a parallel circuit where there are 2 voltage and has a different output voltage where one is 12V constant and the other is adjustable using potentiometer?


texts: PCIE Trace Length Matching Between Tx, Rx, and Clock

texts: Looking at laying out a PCB that will utilize PCIE.  I've read that you want to keep intra-pair trace length to 5mils max and that inter-pair trace length matching is not terribly important.  The current plan was to keep all Tx pairs within 100mils and all Rx pairs within 100mils, but what I'm not sure about is how close to the same length the Tx pairs, Rx pairs, and Clock pair have to be.  I read one site that said that up to a 3" difference is acceptable but that seems rather large to me.


texts: So I have this modification to my electrical system on a motorcycle. The voltage on my motorcycle is 12V and I switched from classic lights to led light (both front and rear). My problem (which I expected) is the now the light are not flashing, they are just ON. I bought some load resistors designed for this. I have 2 pairs (10w 10Ω). I don't know where to connect them. I have below the electrical diagram and marked with red where are those lights, switch and relay. I suppose that I should put them between the switch and the lights (on those two wires near CH and DG)


texts: How to confirm if GPU, CPU or motherboard is broken?

texts:
So I was hacking my internal laptop monitor (basically I was trying to understand the pinout and try to use it externally). During that I used continuity checker to trace circuitry.
It is my old laptop so it was meant for experiments.

Now I did something and I don't know what did I do. Neither internal nor external monitor is not working. I am afraid that by using continuity tool I have damaged some sensitive components.

Is there a way to check approximately where the issue is - gpu, cpu or systemboard?

I know the following points may mean nothing, but maybe they will be usefull:

GPU and CPU heat up
Motherboard supplies power to VGA and internal monitor sockets (including inverter)
I am testing without all unnecessary peripherals (just ram, motherboard(&its intergreted
components), cpu, gpu). It should show blinking bar. Not monitor is
not even started(stays on sleep mode)
Monitors have been checked
I have oscilloscope, external power supply - if checking testpins is the case, I could do it.
I cannot replace cpu or gpu - buying spare parts and checking wouldn't be the best idea.

Please ask any additional information you require. I will try to answer.


texts:
Is it safe to use a passive plug adapter rated for 110 V in a 220 V mains country?

With passive plug adapter I mean something like this:

Those bad boys are also known as "travel adapter(s)", and sometimes contain a status LED that is lit when the mains voltage is present.

This question was inspired by an identical question on the travel stackexchange:

Adapter voltage different to both mains power and appliance expectations

I had a bit of a discussion with a member of that stack, and I just wanted to check with this community.


texts:
If in an AVR microcontroller there's at least two functions for example SPI, Analog Comp and GPIO pins in one 8bit PORT what's the priority of the functions?
for example: If SPI enable first, and then using DDRx trying to set one PIN which used from SPI as GPIO (such as input or output) what's the final function?

EDIT:
Can i setup in a port a multible functions? For example: i want to enable SPI and use the other pins normally as a GPIO pins. or, to enable UART and using other rest pins as GPIO.
How can i do that?


texts: This is a pretty simple question about electric charge flow, but it's something that I just need a clear answer on.  So if net charge on a conductor will spread out over the surface (because like charges repel and want to get as far away from each other as they can).  But what about for an open circuit without a net charge?  Obviously the electricity wouldn't be able to complete a circuit from the positive to negative.  Would the positive and negative charges from the power source spread through the wires, or remain at the power source?


texts: Using a solar car battery charger to power a solar boat?

texts: I am participating in a contest in which I need to build a solar boat (it has to fit into a 1.5' wide by 2' long by 1' high box and draw less than 2"). I currently have a 12V solar panel made for charging car batteries that outputs 125 mAmps and 1.8 Watts. I would strip the case and all unnecessary parts. Will this work for a solar boat? What kind of small motor would I need to use? Is there a lighter, more efficient alternative?


texts: Electric connections for Arduino connected to an underwater linear actuator or servo?

texts:
I am trying to set up an underwater system (depth <= 5 meters, can be dry cause of tide) which is made of:

A linear actuator or linear servo
An Arduino
A sonar ranger.

Basically, I need to program this system with an Arduino, which receives the signal from a sonar ranger and whenever the distance measured by the sonar changes by a user defined amount (I would say 1 cm) then I will have to move the shaft of the actuator/servo in 1 direction by the same amount, with 1 mm precision. All this will need to go underwater.
I have the underwater sonar ranger and I see online that there are underwater linear actuators/servos. I saw here a 2017 discussion about underwater Arduino. I am mainly concerned about the connections, how do I connect everything? That Arduino seems sealed.


texts:
The development cycle of the company I work include building alfa prototypes, sometimes in breadboards, and beta prototypes in printed circuit board assembly.

A considerable slice of the development time is wasted waiting for PCBs prototypes to be builted by PCB manufacturer here in Brazil.
Since the time spent is a lot, I'm thinking in ways to somehow speed up the production of these prototypes in my company.

Do you have any suggestions or experience that you'd like to share on this particular subject? Maybe some cost affordable machine DIY to build PCBs at home?


texts: Supplying multiple devices from one battery

texts:
For my project, I'm planning to charge a battery using solar power. The battery is 12V. After it is charged, it will provide power to the following:

6v to the arduino
12v to a coin acceptor
5v 1A to 10 devices.

I'm confused and don't know where to start, could anyone suggest any books, links, or methods which could help me in doing this.....


texts:
Is it possible to make a capsense sensor that works through a sheet of glass? I have a working capsense sensor on one of these PSoC development boards:

The buttons work fine, but when I put a sheet of glass on top, they don't work. Do I need to bond the buttons to the back of the glass to make this work? If so, do I need to use a particular type of glue?


texts:
I have a dimmer with 2 terminals the configuration was easy,
now I have tried t replace it, unfortunately the replacement has a different terminals configuration without any indication on each terminal.

See the pictures

Brown wire=main phase line

here the circuit board

Any idea about how to setup it is appreciated.

EDIT
Searching the name of the component seems ZC11000 but I have found only Russian and Chinese resources without any technical sheet.


texts:
I bought an IR repeater with the simple schematic:

What is this receiver component? It looks almost like TSOP4838, has the same pinout, but it outputs an encoded signal and I cannot find what is it.

TSOP4838 (right) and this one (left)

Back side:

Short update: any part that does the same will be OK for my needs. Is there any?


texts:
For the magnitude of nF or µF capacitors, I hope I can build them on a PCB board. The capacitor is like a two metal layer and something between them.

Is this possible?

Not buying the capacitor, just design the capacitor on the PCB board. Double metal layers on the PCB board.


texts: how calculate the energy use for starting a 3 phase motor until return to normal work?

texts:
for a project i must calculate the exact energy that used for start of motor until the motor return to normal work
in other words how much energy use for normal work of this motor equals the starting energy ?
the motor is 3 phase 20 Ampere 9KW
will be different when motor is under load ?


texts: Preventing relay contacts from sparking on disconnect

texts:
I am currently using an 80A automotive relay to control a motor.  The relay seems to work great to control the motor, but on disconnect a visible spark can be seen through the clear relay housing.  I understand that the spark could damage the relay and I need to prevent it.

Should I use a diode or a capacitor? Also what size/ ratings are required?

Thank you


texts: Connecting two power supply {LED Light 12v}

texts:
I have 6 strip of lights consisting of approx 100ft total.

1 strip =  16.5ft , 36w, 150 leds, 12v, 3a  .. and can be connected to total of 20 strips end-to-end.

It will be controlled by an RF controller at one end to display patterns, etc and the controller will be powered independently. Each strip is connected to the next strip, and on each's end have an extension female power adapter to get more power of its own to be used to its fully lighting potential.

I have a 20a 12v power supply on hand which I'd like to use to power these, however, I like to know if I center that power supply at 50ft in middle and run the wires from center outwards 50ft to left and 50ft to right would that be sufficient? Wires would be 12guage electrical copper wire I have 200ft spool of that I don't use.

-or-

Should I get another 20a 12v power supply, totalling two, and place one on each end so as not to drop the current load? I ask this because I was given a theory of seeing this as 100ft hose and the pressure would drop the more it is extended whereas the most pressure (light output) would be that nearest to the power supply. So by having one and both end they would push to each other and no current would drop. And each of the female adapter would be fed into the 12guage male that I would attach too this additional power.


texts:
Here is circuit from Horowitz's "Art of electronics" book:

The problem is that I can't get expected signal from R2 resistor in OrCAD:

Here is diode pass both rising and falling edges.Why?

EDIT:
Here is correct settings of voltage source:


texts:
I’m in the process of selecting an op-amp to act as a voltage follower for the input signal into my data acquisition card.

I'm measuring all types of signals just like an oscilloscope would.

Do I have the slew rate I need correct?
I used this calculator and sampling at 1.5 MHz with a peak of 10 V I calculated that I need a slew rate of 94 V/µs.

The reason I ask is I don’t see a lot of choices of rail-to-rail op-amps, through-hole style with that high slew rate.

Slew Rate Calculator


texts: Does the order of connections on a protoboard matter?

texts:
I am a beginner in the field of electronics.  I am trying to learn about applying schematic diagrams to protoboards.

Let's say that I have a schematic depicting connections between pin #2 of a fictional IC chip, then a resistor, then a capacitor, then pin #6 of the IC.

Does it matter if on my protoboard I connect pin #2 to the capacitor first (first as in the first node of the protoboard next to pin# 2), then pin #6 (the next node), then the resistor (the furthest node from pin #2)? Ignore any other components for this example.

They are all connected by the conductive strip of the protoboard so it seems like the order doesn't matter at a basic level.


texts: How is "signal strength" characterized on a coaxial cable?

texts:
I've come across the Shannon-Hartley theorem, so I assume that a "signal" must have some notion of strength or "power" that can be referenced to some noise level (and whose power can be varied at the signal source).  But what form does that power take on a coaxial cable?

E.g., is it a maximum voltage that can be observed between the conductor and the shield?  Or something else?

And what is a typical value for this power measure or limit – say, as applied to RG6 cable for residential data transmission?


texts:
I'm trying to apply a filter to an audio signal in MATLAB and having some trouble processing it.

So far, I have a transfer function that describes a K-weighted filter, and I am able to create a bode plot that looks correct.

Here is the script for that one:

I have another script that reads audio from a .wav file, plays it, and plots the waveform.

That works properly too. Now I want to run that audio file through the K-weighted filter but I'm having trouble with that part.

I am able to use the "designfilt" and "filter" functions to create various filters and process the audio, but I can't get that to work with the transfer function I've created.

My transfer function PF is expressed in the z domain, but it doesn't show up as a proper digital filter in MATLAB.

Is there a way to create a digital filter from my PF transfer function or its coefficients directly?

I've tried using "filtfilt" and "lsim" to process the audio but I haven't had any luck yet.

I've also tried "output=filter(PF,audio)", which returns an error message saying there aren't enough input arguments, and "output=filter(b1,a1,audio)" which returns a matrix that says "NaN" repeatedly.

I'm sure there's something obvious I'm missing or some syntax errors, hopefully somebody here can point me in the right direction.

Thank you for your time.


texts:
I'm trying to understand the resolution of the problem 5.11, but I can't understand how she gets the expression in the rectangle:
$$\dot{x}_1=-x_1+2u$$
How can I get the expression in the rectangle?


texts:
I'm looking for a variable AC power source for use in some electromagnetics experiments and longer term for testing inductors, transformers, core material frequency response, and that sort of thing.

I'm thinking my dream instrument would have voltage variable between 0-125V, be capable of providing a few amps, maybe 10A at low voltages (say 24V or less), accept an arbitrary waveform from my signal generator to determine the AC out (possibly including a DC offset), and have a frequency response from DC to say 10kHz.

I'm willing to compromise on all of those however, especially to get started. I already have a variable 60Hz AC supply, one of the Variac + Isolation transformer type. So the first big addition would be variable frequency.

I've done a lot of searching around on the web, and such a device seems to be difficult to find. The closest thing I've found is called an AC Power Source and these seem to have a limited frequency range, especially on the lower end, bottoming out around 45 Hz it seems. They also seem to be limited to sinusoidal waveforms. These have great power capabilities, but appear to be somewhat targeted toward mains supply simulation for compliance testing or whatever. At about $2k to get started, they're also a bit more than I wanted to spend for essentially academic/hobbyist purposes. Here's an example of one I found:

Based on this answer I'm inclined to think a possibly better approach would be to use an audio power amplifier. I think the frequency response would be good enough and taking in an arbitrary waveform is natural for such an amplifier.

I'm not sure about the peak voltage I'd be able to attain with such an amp, I expect it would depend on the source voltage (say 25 VAC in the amp suggested in the answer above). But I'm curious enough about that approach that I'm thinking about hooking up my 40+40W Pyle amp just to see what it can do :)

So I guess my question is this:

Is there a standard lab instrument available for this sort of thing and I just haven't found the right search term yet?
Or should I really be thinking about a power amplifier for these sorts of purposes and be focusing on how to get the output voltages and currents I want, possibly by adapting such a circuit?


texts: Unknown hardware filter/amplifier in setup

texts: I found the following picture on the internet. To be honest, it was the first time I saw such a (filter/amplifier?) plugged in an oscilloscope. Anyone knows which device it is? Thanks in advance ;)


texts: MQ-4 sensitivity characteristics - raw data

texts:
I need to convert Rs/Ro ratios of my MQ-4 sensor to PPM. For that I found the sensitivity plot in the datasheet (https://www.sparkfun.com/datasheets/Sensors/Biometric/MQ-4.pdf). However that is a pdf and an image in it. How can I get the raw values out to get a precise fit function? Is there any standard way of doing that, or do I simply need to use a look&feel approach or fiddle around by counting pixels?
Thanks!


texts: DF Robot Electronic Solonid Lock Relay Pinout

texts:
I'm trying to figure out what I'm looking at on this pinout diagram.  Specifically I'm looking at how the line voltage connects to the relay in this figure.

I'm pretty sure that NO stands for normally open, COM stands for common connection, but I don't know what NA stands for in this diagram?

The lock can be found on their website here


texts: In below picture, is ammeter AC or DC? Is there direction for connection with load in series? If so what if I connect in wrong direction?

texts: This is front view of analog ammeter. There are 2 terminals with nut and bolt behind it but nothing marked neither plus nor minus.


texts:
Looking for some general guidance on stepping down 110V Ac source for A/D conversion.
I am interested in capturing some of the harmonics in the source for analysis. My worry about using a step down transformer is hysteresis/ core saturation causing interference.
My requirement is to faithfully reproduce the incoming 110V AC signal at about 3V AC since my microcontroller analog input can only tolerate 3V.
Thanks


texts: Is it possible for the system of equations of an electric circuit to not have a unique solution?

texts:
When using Kirchhoff's circuit laws and Ohm's law to model the system of linear equations corresponding to an electric circuit (so far, circuits involving resistors and sources only), I haven't been able to find any circuit that yields an inconsistent system nor a system with infinite solutions.
Thus I was wondering if it were possible that the resulting system of equations didn't have an unique solution, and if so, what would be the physical interpretation for such a result?
Also, in case it is not possible, what would be the scientific result that supports that fact? For the sake of clarity, I attach an example of the kind of circuits I have been working with and its corresponding system of equations.


texts: What is this glassy black bulge on a keytar button chip?

texts: I'm disassembling a non-functioning toy keytar. This is the chip behind a couple buttons, including an on/off button. What could the black, glassy bulge component be?


texts: How to use multiple LDR to trigger a led?

texts:
Whats the best way to use multiple LDRs to power up an LED? Currently I’m using one LDR which turns on an LED when it senses light. But now I want to use three LDRs (at different locations) to trigger the same LED. The LED should turn on when any of the three LDRs sense light.
Thanks in advance!


texts: IPA becoming unobtainium, can I use denatured alcohol to clean vintage computers?

texts:
Due to COVID-19 and peoples' practice of hoarding, IPA is becoming incredibly difficult to find where I live (and online).  Since we are all home so much these days, I like spending some of that time restoring vintage computers.  My normal routine is to clean the PCB's with 99.9% IPA and use denatured alcohol for cleaning stubborn pen marks, etc. on the case.  I often use glass cleaner for the plastic cases too.

I have a bit of denatured alcohol which doesn't seem to be hard to get.  So my question is, will I damage my electronics by using denatured alcohol (pictured below) to clean the boards?

EDIT

From what I understand, denatured alcohol is an umbrella term for the fact of adding a denaturing ingredient to alcohol.  This could be lots of stuff like kerosene.  One reason is to prevent people from drinking it.  Also, IPA is denatured as well (again, from my understanding).  But if it helps any, this is typically what I use:


texts: Output voltage of unity-gain buffer varying with current?

texts:
I'm working on a VLC+IR transmitter that runs from batteries. I decided to use an LM317 so that the discharging battery wouldn't really affect the current through the LEDs. (Disclaimer: I've never worked with this IC before in my life.) I use TINA for simulations and I found a spice model of the 317 somewhere on the internet.* Its output voltage dropped when connecting the LEDs, so I connected a unity-gain buffer op-amp between the two.

The transmitter has two "outputs": a white and an IR LED. They can work together or one-by-one. VG1 and VG2 are square waves with a frequency of 1 MHz. When I turn off SW-SPST2 or SW-SPST3, the other is working properly. However, when I try to operate them at the same time, one of them stops behaving normally. I checked the op-amps output voltage (VM3), and it keeps changing between 2 and 5 volts, approximately. I don't understand why, as the op-amp has a really low output impedance, thus the output voltage shouldn't be affected by the load.

So, my question is: First, what is the cause? Simply a simulation mistake? Second, I'm not really convinced that the LM317 model is correct, so, am I correct assuming, that its output voltage drops with a load?

Edit: Yes, I made a mistake by putting a 2k resistor to the LM317. I just wanted to produce a stable ~4 volts. Now, I replaced it with 540 Ohms, the nominal value for which the output is about 4.06V. The problems are still there, whether or not I use the op-amp. If I don't use it, the voltage drops after I connect the load. If I do use it, I still can't use both the LEDs at the same time.


texts: Multisim producing very low comparator output voltage

texts:
In the images below I have the same schematic in multisim, one snapshot for each state of the comparator. I've got the VCC pin connected to 12VDC and the ground and VEE pins to ground. There is a distinct difference between the two states, but 15.8 mV for a "high" doesn't seem right. Shouldn't it be VCC? What am I missing?

Note: I just realized that one of the voltage labels is over the pin, that's pin 8 that's covered.


texts: Please help me understand this charging algorithm

texts:
I am trying to plan a stand alone system, and for that I will need a charge controller. I am looking at a few models from the company MorningStar. I have understood what MPPT is, and decided to not use MPPT because of the cost.

Currently I am looking at their series,  ProStar, which they themselves call a "mid-range solar controller". Datasheet.

Below is a screenshot from the datasheet, which is relevant for my question:

I do understand that each type of battery: gel, sealed and flooded, have different specifcations. I plan to use a deep cycle gel battery. And I do understand the temperature compensation. I also understand the load disconnect and load connect voltage thresholds.

What I don't understand are the different stages of the charging. I believe it is called a charging algorithm, even though the data sheet does not use that word. Am I right?

Here is what I think I understand. But please correct any misunderstanding I have.

1) Full charge: When the insolation is not enough for the solar panels to reach the optimal charging voltage, it charges with whatever voltage is yields. Of course this only happens if the battery is below some voltage threshold where it is safe to charge. But which threshold?

2) PWM regulation: The insolation is so intense that panels yield a voltage greater than what is good for charging, in which case the voltage is reduced, using PWM. I think it must be charging with the "Regulation voltage", since regulation means changing (increasing) the charge/voltage of the battery.

3) Float: When the voltage of the batteries is at the optimal level, it should not be "regulated" any longer, but instead just maintained at that level. So I guess it charges with the voltage that is also the maximum healthy voltage for the battery. I think this number is what they call "Float".

4) Equalize: I don't know what this does, please teach me!


texts: Capacitive voltage drop - surge and safety

texts:
Background
I'm designing a power amplifier and I want to sense power-drops early, in order to properly shut down the class-D amplifiers, SMPS's and save status in the microcontroller, before brownout occurs. In order to do this, I'd like to rely on AC mains sensing with an AC-input opto-coupler.
I could do this in a very simple way, by adding appropriate series resistor(s) to the LED's, but with  about 2mA that consumes about 0.5W permanently. Hence I'd rather rely on a capacitive voltage drop.
The 'problem'
I'd like to protect this sensing circuit from the nasties that come from the mains power line. So, I've looked at the surge behavior of several components involved:

opto-coupler (SFH6206): 2,5A surge, check
X2 safety series capacitor (TDK B3293 47nF): OK for series operation, this is however the problematic part for surges.
series resistor (Panasonic ERJP08 ): 10k resistor should be able to endure 160V during surges.
TVS diode across opto-coupler and series resistor (Littlefuse 8.0SMDJ100CA): can absorb enough power and clamps to appropriate  voltages with regard to the other components.

My questions
In normal operation, the below schematic, using the components enlisted above, behaves just fine and will be reliable. I am however hesitant when it comes to power line surges.
First of all, what exactly is a power line surge for this type of domestic, consumer type device for indoor use. I've seen most references suggesting a 8/20µs peak with a top of 6kV, I've however also seen documents suggesting a 0.5µS rise and 6kV peak, with 100kHz decaying oscillation waveform, with a 60% decay between the first and every following positive or negative peak. I'd like some guidance from knowledgeable people here.
It also seems that any thermal fuse or circuit breaker will react much slower (in about 10ms), so any surge damage will occur before mains power is cut off. Correct?
Last problem, assuming I have to consider the 8/20µS 6kV peak, how will this affect the X2 capacitor. It is certainly out of specs. But looking at X2 safety capacitors, pulse types are not recommended for series operation and types for series operation do not withstand surges very well.
Below is the simulated schematic.

During the surge, I observe the following peak values in the simulated circuit:

D3 clamps at 144V/18A, peak power of 2.5kW, this is OK.
R1 clamps at 141V/15mA, this is OK
C1 and C2 conduct 18A while rising up to 2.9kV with a peak power of 49kW, this is problematic, I think.

So my additional question is: can this be improved upon or should I accept that the capacitor will suffer and self-heal? And if it does, will it be fit for further use? It's capacitance will drop, current through the opto-coupler will be affected, but by which order of magnitude can I expect degradation?
As a last note, I can imagine that a series protection device can protect the X2 capacitors. But which type of device should that be, it should be able to absorb enough energy, it should act fast and it should have low resistance in normal operation.


texts: I want to make a electronic device powered by a 3.7 V battery. And to charge the battery a 5 V charger will be used. The maximum voltage for this device is 3.7 V - 4.0 V. But when I connect a charger the device will get 5 V. How can I protect this device from over voltage?


texts: Unexpected pulses in the output signal from IR Detector

texts:
I have a Sharp GP1UX311QS IR detector connected to a msp430 launchpad. I wrote a small bit of code to read the output signal from the detector and print the on/off times. However, without emitting any IR light (from a remote) a small pulse appears on the output signal every 5 to 20 seconds. I tried shielding the detector with aluminum foil for about 5 minutes and the random pulse never showed up. After removing the foil the pulse starts showing up again about 20 seconds later.

Screenshot of the signal from my oscilloscope:

Took a few samples of the small pulse to see how much it differed:

I also tried just a simple circuit that supplies 3.6 V to the IR detector and get the same results as above when connected to the launchpad.

The fact the detector only detects modulated IR at 38 kHz makes me wonder why I get interference. Any ideas where the interference may be coming from and what I can do about it? I would prefer a hardware solution rather then accounting for it in software. Thanks.


texts: How to attach a button to the circuit board on a key fob?

texts:
I have a power lock key fob for my Subaru where the unlock button has detached from the circuit board. I would like to try to re-attach it, but I am not sure about the right method. Is there some sort of special glue that I should use? It does not look soldered.

Here's the photo of what the circuit board looks like:

Any additional advice for this repair would be appreciated.


texts: Why do I get this weird curve for impedance vs Frequency

texts:
I am currently working on a simulation for an RLC circuit in Pspice, I am trying to plot the impedance vs frequency curve. After a good while of trying out stuff, I always get such weird curve. Not sure if the function is wrong on its very own

In case you wondered, this is my circuit.


texts: Append Two String to LCD Using MikroC and Proteus

texts:
I tried to read EEPROM values and display that value with a string.

This is my MikroC code:

char shed;
char shedn[]= "S";
char shedfn;
unsigned shedno;

void main(){
  shedno =  EEPROM_Read(0x00);
  shedno = 256 - shedno;
  delay_ms(50);
  WordToStr(shedno, shed);
  strcpy(shedfn, shedn);
  strcat(shedfn, shed);
  Lcd_Out(1,1,shedfn);
}

All LCD code has in my code and not mention here and it is working fine.

I am using pic16f887 microcontroller and that give following error in proteus.

[PIC16 CORE] PC=0x019E. Indirect write of 0x53 to address 0x0080 is itself an indirect write. [U1]

[PIC16 CORE] PC=0x0183. Indirect write of 0x00 to address 0x0080 is itself an indirect write. [U1]


texts:
I am trying to create a 4th order active band-pass filter. I am using this site, for calculations, as was once suggested by Andy aka.

I am able to get Q factor and center frequency just right for 2nd order MFB band-pass to achieve wanted filtering. However, I am unsure how to add the second stage to the first.

Will there be any loading effects by the second stage, should I just "copy/paste" the first stage? In general how would I choose the second stage resistors/capacitors, to get 4th order band-pass filter with -3dB at 20Hz and 200Hz?


texts:
Iam looking at the datasheet of a dual MOSFET (IRF9358PbF.) which contains 2 drain pins and 1 source pin for each MOSFET.

What is the purpose of having 2 drains, when there is only 1 source pin?

Is it for increased current capability? Since drain current is same as source current, shouldn't the source pin be also 2 pins?


texts: Between a full wave rectifier circuit and a half wave rectifier circuit which has a better(i.e lesser) voltage regulation?

texts:
I know that voltage regulation is give by

$$ V.R.= \frac{V_{nl} - V_{fl}}{V_{fl}} \cdot 100 $$

where \$V_{nl}\$ is the no load output voltage and \$V_{fl}\$ is the full load output voltage.

I can easily solve for a particular case but can I find out theoretically which one has a better voltage regulation?


texts: Microcontroller Vol Maximum Voltage compatibility

texts:
I am having this microcontroller - S32K142 64 pins - 5V Core voltage
I have the below RESET signal connection which is provided by the MCU to the below transistor (which provides RESET to another microcontroller)

Transistor Datasheet BCR116W
I am checking the Vol and Voh compatibility between the microcontroller pin out and the Q0101 Transistor.
Suppose, if the Microcontroller outputs high, from the Microcontroller datasheet, Voh and Vol are not provided directly. They have only mentioned as Vdd-0.8V for Voh and 0.8V for Vol.
My questions :

I am assuming the Voh of the microcontroller to be 3.2V (4V-0.8V=3.2V) (min). Is my assumption correct?

If suppose my microcontroller provides a high to the RESET line, I am guaranteed atleast a 3.2V on the RESET, which happens to be greater than the worst case maximum turn on voltage of the transistor (1.4V).
Since, 3.2V > 1.4V - Transistor will turn ON. (Collector current is in the 250uA range)
But if I give low at the RESET pin of the microcontroller, since the Vol(max) as specified in the datasheet is only 0.8V, and the maximum turn off voltage of the transistor as given in the datasheet is 0.8V, there seems to be a mismatch in the compatibility, right?

Since, in worst case conditions, my Microcontroller outputs a 0.8V on the RESET for LOW signal, the maximum voltage that needs to be provided for a guaranteed turn off of the transistor at the worst case scenario is less than 0.4V (as mentioned in the table on page 3). Am I correct?
If my microcontroller provides 0.8V and the transistor turn off voltage threshold is 0.4V, the transistor might turn on and trigger falsely right?
Is my understanding correct?
If this is the case, what is the work around in the design?


texts: I'm doing AC theory, and I'm looking for different formula to find induced back-EMF. Given inductance, voltage, current, frequency, I'm able to find inductive reactance, current and voltage on each inductor, but I'm really struggling to find something to help me put it together. If anyone has any tips at all they would be greatly appreciated!


texts: What applications require isolated transformers?

texts:
I am reading that the principal disadvantage of autotransformers is that unlike ordinary transformers, there is a direct physical connection between the primary and the secondary circuits, so the electrical isolation of the two sides is lost. What applications that use a regular transformer require the high and low windings to be electrically insulated from one another?
Thanks!


texts: SAMD21 SERCOM / UART problem: cannot enable RX and TX

texts:
I've been trying to set up a USART on an ATSAMD21E18A-MU and have been running into issues.

Currently, I've narrowed the problem down to the fact that CTRLB.RXEN and CTRLB.TXEN never go high after enabling the USART.

My hardware has TX on PA04 and RX on PA06. I'm trying to use OSC8M as a source for Generator 3, and Generator 3 for SERCOM0_CORE. Trying to get everything relevant running at 8MHz.

I'm trying to set up 8n1, asynchronous mode, fractional baud rate, 16x oversampling, etc.

See this gist for the full example.

From the datasheet, info on CTRLB.RXEN reads:

  Writing '1' to CTRLB.RXEN when the USART is disabled will set
  CTRLB.RXEN immediately. When the USART is enabled, CTRLB.RXEN will be
  cleared, and SYNCBUSY.CTRLB will be set and remain set until the
  receiver is enabled. When the receiver is enabled, CTRLB.RXEN will read
  back as '1'.

(There is similar text for CTRLB.TXEN.)

I spin check these flags after I enable the USART (line 115 and 116 in the gist) but they never go high.

Simple question: what am I missing?

I feel like I picked over the datasheet with a fine toothed comb...

Any and all help appreciated.

EDIT: discovered an issue with my use of PORT_WRCONFIG_PINMASK in the example code (e.g. PORT_WRCONFIG_PINMASK(4) vs. PORT_WRCONFIG_PINMASK(1<<4)) but currently does not resolve the issue.


texts:
Actually I'm trying to understand how to control a BLDC motor using trapezoidal method. I've found two illustrative images that show how to PWM each motor phase:

First

Second

In both of this images, the principle is the same. But in the second image there's also low side driven low when high side is high inside PWM part.

Which one of this image is correct and why? (or which is better and why?)


texts:
I can connect many resistor in parallel or series to get a final resistance I want in case when I have no necessary nominal out of the box.

I wonder is there such trick that will allow me to easily change varistor's nominal. Say, originally I have a varistor that changes its resistance from 0 to 200 kilohm. Can I construct a simple circuit that will map the range to, for example, 0-10 kilohm?


texts: logic mosfet instead relay to in central phone

texts:
I want to have a inter communication between two phone.I need to know how can I do it without relay in fact I want to do it with mosfet.Is it work?
If answer is yes,can I use mosfet in both of line (tip or rinng)?


texts: Dual photo transistor component reference (like used in old mechanical mouses)

texts:
Context : I'm trying to implement a way to detect the rotation speed of a motor (no problem) and also get it's direction.
I know all the basics, don't worry :) (placement difference between 2 photo transistors permitting to get the direction etc)
To do my things, I salvaged some old mechanical mouses, took the "rotation wheels" (technically, they are no coding wheels as there is no code in there) also took the IR diode, and most importantly the photo transistors.
These photo transistors got 3 pins, in the middle the supply voltage and on each end the signal pins for each photo transistor. Easy, very nice.
The 2 photo transistors in there are separated by a very small distance, which is realy great and induce the need of only 1 component easy to install
Problem : I'd like to be able to buy some brand new DUAL photo receivers like the ones described before...
But I can't find any reference. I tryed Farnell, radiospares, aliexpress, a lot of key words, but no success.
Some of the photo transistors I salvaged got some references on them, but this leads to nothing (real nothing, not even one result)
Maybe there is a specific name (which I don't know) that would give me lots of results?
Edit : I really search for the DUAL ones, not SINGLE. of what I saw until now, 99.9% are single channel :'(
Please, point me to a component I can actually buy :)
Thanks by advance !


texts: REF02 not working - 4 channel 5v DAC circuit, star gnd connection, stripboard layout

texts:
I've connected my circuit as in the diagram, with a 15V PSU powering it (both amps are connected the same way) - but the DAC seems to be drawing too much current for the REF02 to handle, even though p.24 of the DAC datasheet describes using it in this config. What have I done wrong?

Many thanks for your help

DAC8555
REF02
LM358


texts: Raspberry Pi- SPI waveforms are wrong. Clock missing pulses

texts:
I'm trying to get read data off and an LTC1867 ADC chip. My previous questions are based around this for more info

Raspberry Pi- SPI with Hi-Res Bipolar ADC Chip (LTC1867). Wrong values being read
How to measure bipolar analog signal accurately (to 1mV) on raspberry pi

My values were consistently wrong. I think my code works correctly. I have tried both using pigpio and spidev and both give the same wrong results.

I used piscope on two different raspberry pis to make sure the problem wasn't from my pins. The results are shown below. This is different from what I would expect from the datasheet as the pulses aren't even. but there are 16 pulses nonetheless.

My main questions are:

Does anyone have any idea why my waveforms are coming out like that/how to fix it
Why do I get random values?
Would bitbanging/software SPI solve the issue?


texts: Size and weight of DC-DC vs DC-AC at equivalent powers

texts:
I am looking at designing two power systems for a project and was wondering, at equivalent power, let's say 10kW, what is the system that is easier to design, can be smaller in volume and lighter in weight: a DC-DC converter (63V - 37.5V to fixed 430V) or a DC - AC (63V - 37.5V to 230V AC at 50Hz)?
Thank you for your help!


texts: Data lost writing on Arduino serial port. Overflow?

texts:
I have an Arduino connected to a linux box (a Raspberry Pi). I'm reading an analog pin and writing it out with Serial.println() together with the value of millis()
The serial port is running at 9600bps

Something in the lines of:

void Setup() {
Serial.begin(9600)
}
void loop() {
    Serial.print(analogRead(A0));
    Serial.print("\t");
    Serial.println(millis());
}

On the receiving end I see a continuous stream of 5 or 6 seconds, then a gap of 2 seconds with no data, then another 5 o 6 seconds full of data. I'm not "seen" it live but plotting the  value of millis() with a data read from the serial port.

I think it might be that the data is lost in the write buffer of the arduino, or that something else takes processor time every 5 or 6 seconds (there is an unused ethernet shield attached) or maybe the Serial port writes in bursts.

When I increase the baud rate to 115200 I still get time gaps, but they seem more random.

Update:

Increasing baud rate to 38400 removed the gaps in the samples (gaps measured in arduino millis() time)

Another strange thing was:

On the receiving end I was doing cat /dev/ttyACM0 and piping it to awk which added the system clock to each line received. Then I plotted received time vs system time, and it was not a straight line, but a ladder like plot. Removed the  innecesary cat and the time was back to normal.

It turns out cat /dev/ttyACM0 | awk {print} is not the same as </dev/ttyACM0 awk {print}. It seems cat does some strange buffering.

Now I seem to get every value read by the arduino.


texts: LED + resistor in parallel with equivalent resistor, all in series with a larger resistor, LED not lighting up

texts:
I don't know whether I'm missing something obvious here, but I'm pretty confused. Here are a few diagrams (the ✔ or ❌ indicating the status of the LEDs when I tested it):

Sorry for the lack of labels; call the 10K resistor R1, the left 1K resistor R2, and the right 1K resistor R3.

My question is: Why doesn't the LED come on in the first diagram?


texts: Testing limitations of a low bandwidth cheapie oscilliscope

texts:
Learning basic electronics.  Have a few multi-meters.
I'm researching "cheapie" less than $100 oscilloscopes.

I read that the most important spec is bandwidth.

I've noted that $40 to $100 scopes have severe bandwidth limitations ranging from 200K maybe up to ~1.0 MHz with reasonable (+/-5% ?) accuracy.  I've noted one ~$80 scope that advertises 100 MHz bandwidth, but is reasonably accurate only below less than half that, maybe 30 to 40 MHz.  I'm wondering if all the cheapies greatly exaggerate their specs like this.  They call it "Chinese specs", I've learned.

What I would like to know is 1) what type of testing can be done with reasonable accuracy with such low bandwidth scopes, and 2) what types of testing should be totally out of the question/avoided.

I understand the guideline that a scope should have a bandwidth 5 times the frequency of the things being measured.  My question deals with what types of circuits generate frequencies that are in this lower bandwidth range.

My scope functionality question pertains to testing these kinds of circuits: Beginning hobbyist testing such as in Platt's Make: Electronics or Basic Arduino type systems.

$100 is my absolute limit; preferring $40 to $80 range.  This is just for a "toe in the water" "explore the basics of scopes" sort of thing.  I know that if I spend "just a mere $200 more" I can get a "real scope."  And no, don't want to mess with used or eBay.

Here are 4 scopes in my price range:

https://www.amazon.com/dp/B07QML4LJL/?coliid=I3UEZDO1F0D9V8&colid=3B04RKX85L5W0&psc=0&ref_=lv_ov_lig_dp_it
https://www.amazon.com/dp/B07V6795WP/?coliid=I3IXRDY73S9RI5&colid=3B04RKX85L5W0&psc=1&ref_=lv_ov_lig_dp_it
https://www.amazon.com/dp/B07XBL4BTL/?coliid=I31BECTM93K5LJ&colid=3B04RKX85L5W0&psc=1&ref_=lv_ov_lig_dp_it
https://www.amazon.com/dp/B07TNPYLS5/?coliid=I1RS7IOEMH7PJ6&colid=3B04RKX85L5W0&psc=1&ref_=lv_ov_lig_dp_it


texts: Generating a constant-amplitude triangle wave from a square wave

texts:
I have designed a circuit that can generate sawtooth and arbitrary duty cycle pulse waves controlled by some variable DC current source \$I_0\$, giving a frequency proportional to this current.

The sawtooth is generated by charging a capacitor with \$I_0\$ and discharging it rapidly when it reaches some voltage \$V_0\$, controlled through a 555 timer.

I can then use that to generate a square wave by putting the sawtooth output through a comparator. The duty cycle can be adjusted by adjusting the reference voltage of the comparator. (I know this is not the most efficient way to generate pulse waves, but it's how I designed it to have frequency proportional to \$I_0\$ in the same way as the sawtooth.)

I now want to use this same circuit to generate a triangle wave with the same frequency as the other two oscillators. The obvious way to do that would be using an integrator on the square output, but that will give me an ever decreasing amplitude with frequency, and that's not something I want. I need amplitude independent of frequency.

If the text is too confusing, I can draw a schematic once I get home.


texts: What's the name of this type of connector used for high current

texts: The connector below often found on equipments with high current output. What's the name of it? And what's the other end to mate with it?


texts:
I'm a student making a simple Arduino-compatible board similar to the Pro Micro and am going to put a USB connector on the board.

The schematic in the above link doesn't show any kind of EMI/ESD protection circuitry, and I've never used any in the previous boards I've made, but this time I did some research and found this is recommended.

I'm reading an Atmel application note giving recommendations for USB interfaces and it has the following:

There are a few similar questions on here, but I still am unsure of a few things:

Should TVS or Zener diodes be used? The diodes in the Atmel application look like Zener diodes to me, but from what I've read is seems like TVS diodes would be more appropriate?
How close should the breakdown voltage of the diodes be to 5V?
How high do the voltage ratings of the diodes and capacitor need to be?
Is the SHIELD pin shown on the diagram the "legs" of an SMD USB connector (i.e. the casing)?

Thanks for your advice.


texts: Using a Main Surge Protector for only branching out other surge protectors

texts:
Whenever I try to find information about this question it always says that it is not good to plug in a surge protector into a surge protector because you can overload or overheat the protector or circuit.

I was wondering is it perfectly fine to do if you do not overload the surge protector?

High rated surge protector 15a with 4000 joule protection has only other surge protectors plugged into it not bother electronics just for the purposes of charging that higher joule protection.

Additionally I read up and it states that there is an increase in protection if two surge protectors are plugged into each other. Is this true?

Lastly, the worse case I have in my configuration is a main surge protector with a 15a cable (that serves as the main one) that has a smaller surge protector and then an extension cord, could this power a 50 inch tv and baby monitor camera or will it not have enough power? It is under 50 feet of surge protector/extension. Someone on another forum said it might lose current and under-power the tv, damaging it.

The main question is, is this configuration safe and will it degrade any of my parts or not provide enough power in regards to my tv and camera as mentioned above? Will it cause some kind of fluctuation if it is not overloaded?


texts: Single-supply amplifier design without output capacitor?

texts:
I'm working to create a small amplifier using a single 12V supply. One (of several) limitations I have encountered is the necessary size of the output capacitors(1000uF to deliver 20Hz into 8ohm loads) and the associated power loss (1000uF @ 20Hz has nearly 8ohms impedance so it is using 50% of the output power).

Is there any Single Supply amplifier topology that does not require an output capacitor?


texts: Protecting malfunctions in relays which operate roller shutters (motor, inductive load)

texts:
I have a circuit used to control roller shutters in my home, which roughly can be seen in the schematic below.

simulate this circuit – Schematic created using CircuitLab

It works, but after some months, some relays stopped working. The relays are rated 16A 250V~, and they operate at 5V. We suspected some faulty components (although they were bought in a reputable store) and after some extra failures I discovered that light "percussive maintenance" solved the issue, so I suspect that the relay contacts were somewhat slightly fused together, if that makes sense. But it's not a full-blown-fused-contacts scenario, just... slightly enough to not switch anymore until gently tapped.

I realized that I had neglected to add a snubber there. I am more a microcontroller guy myself, so I read a little bit on the internet and decided to add a snubber, specifically: this KEMET one which is a 100n 100R. I was hoping it would make sense in this circuit, and was unsure if it was better to put them across the contacts or across the load and I ended up trying it across both common-up and common-down in the cover contacts.

Still, when stopping the shutter movement from either directions, I have sometimes seen sparkles inside one (RLY1) or both relays.

What should I improve, and what are my options? The PCB is done and is somewhat big for a DIY small hobbist like myself. And it is placed in a hard-to-reach small enclosure. I thought that maybe I didn't properly place the snubbers, but physically it's hard to test them in a lot of different positions. I was considering the option to change the RLY1 for a SSR with zero-cross (hoping the zero-cross would solve itself some of the issues), but still, it would mean to redo and patch some electronics and I fear being mistaken and ending up burning the SSR.


texts: How much is parasitic capacitance of soldering pads on PCB?

texts:
I mounted a Resistor (SMD, Size: 0603, Resistance 500MOhm) on a PCB.
What is the value of its parasitic capacitance?
How would it change if it were 0402 in size?
Does it depend a lot on the individual component or is it solely dependent on the distance/size of the soldering pads?


texts: What's wrong with my answer finding the resistance?

texts:
This is the question and the solution:

Here's my answer:

My answer was incorrect, though I believe my analysis was correct. Can anyone point my mistake? I hope it's not with the signs.


texts: DIY Bluetooth speaker circuit won't turn on

texts:
I'm making a Bluetooth speaker and made a schematic which I'm using to follow to build the speaker.

It's loosely based on this DIY video I saw online, here's the picture of the relevant parts I copied:

Problem is though that when I tried the second picture out (proper looking schematic) it worked normally for my speaker (in my case I used 4S batteries each 3.7V) but when I tried out my schematic with the step up converter, it just stopped working.
Now my intention was to step up the 12V input to 16.8V for the battery board and the Bluetooth board too (Bluetooth board can handle higher voltages so it's cool) but with the way I did it, it was wrong. I even tried to plug in a power supply of 12V but it started making some high pitched noise, fortunately there was nothing burning.
Any ideas with how I can fix this issue?
EDIT: Links to the Bluetooth Amp and the Boost Converter for additional info:
https://www.ebay.co.uk/itm/Bluetooth-5-0-TPA3116D2-Digital-2-1-Audio-Amplifier-Board-100W-50W-50W-DC-12-GS/333643187264?_trksid=p2485497.m4902.l9144
https://www.amazon.co.uk/gp/product/B00HV43UOG/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1


texts:
I need to latch an INT output with a time width of 7 ms. This signal is generated by an RTC clock and I need to enable an LDO with it. The LDO powers an MCU, which at the end of its program should be switched off.
The main issue is to design a nA range circuit.
I've seen some On/Off Controller ICs for Maxim, but they have debouncing and they will not work with this time width.
EDIT:
Here is the circuit I've designed.
I am using a TPS73733 LDO and a RV3028-C7 RTC. The MCU is an ATmega328P


texts:
I'm implementing a serial bootloader on an ATSAME51N20A (Cortex-M4). I'm reading in packets of UART, and writing them to internal flash. For some memory addresses the flash writes work fine, and for others it doesn't work at all.

Here is the datasheet. I have checked all the register configurations that I can find and it all seems to be OK.

Here is my initialization code :

void init(void)
{
     GPIOInit();
     USARTInit();

     NVMCTRL->CTRLA.reg = NVMCTRL_CTRLA_AUTOWS | NVMCTRL_CTRLA_WMODE_AP | NVMCTRL_CTRLA_PRM_MANUAL;
     hri_mclk_set_AHBMASK_NVMCTRL_bit(MCLK);
     hri_mclk_set_APBBMASK_NVMCTRL_bit(MCLK);

     PAC->WRCTRL.reg = PAC_WRCTRL_PERID(ID_DSU) | PAC_WRCTRL_KEY_CLR;
     MCLK->AHBMASK.reg |= MCLK_AHBMASK_DSU;
     MCLK->APBBMASK.reg |= MCLK_APBBMASK_DSU;
}

Here is my writing to flash code:

#define APPLICATION_START_ADDRESS 0x8000
#define PAGE_SIZE (512U)

void programApplicationFlashPage(uint32_t pageOffset)
{
    uint32_t *flash_buf = (uint32_t *) (APPLICATION_START_ADDRESS + (pageOffset * PAGE_SIZE));
    for (int i = 0; i < PAGE_SIZE/4; i++)
    {
        flash_buf[i] = *(uint32_t *) (memoryLocation + (i));
    }
}

I am able to write flash pages from addresses 0x1A00 through 0x1E080 (which is offset 145-175) but before and after that, the memory that was supposed to be written to does not change.

According to the datasheet RUNLOCK is responsible for write protection of NVM and I verified this to be set to unlock all NVM sectors (0xFFFFFFFF).

What else could be preventing me from writing to all of NVM?


texts: Why are male pins used for in circuit serial programming?

texts:
In most boards, the ICSP (in circuit serial programming) pins are of the male type. Is there any reason, guideline, standard or best practice that recommends this?
If not I would like to use female ports so that the power and ground cannot be accidentally shorted or the reset (active low) accidentally activated during repair or troubleshooting.
Most good quality programmers also have female ports for programming - I wonder why?


texts: Why would a Diff Amp require both inputs to have a DC path to GND to work?

texts:
I'm looking at using a NI PXI-6255 DAQ card and I noticed in the manual it says "Both inputs of the (diff amp) require a DC path to ground in order for the (diff amp) to work."

Is this a common design constraint to use a differential amplifier?  If both inputs are floating, shouldn't it be able to reference each input to the amp's ground to take the differential voltage without needing a DC path?


texts:
Newbie here regarding contactors and relays, i had this contactor datasheet https://www.gavazzionline.com/pdf/CC50-CC65.pdf. I'm trying to identify how long the contactor would last and I find the durability category, what's the difference between mechanical and electrical? does the mechanical durability means how many cycles the contactor would work w/o load and electrical means has load?

Also, this durability is for the poles of the contactor? not its coil for activating the contactor?

Does coil for activating the contactor has durability also??

I find it hard to read datasheet that are not detailed at all since i have no one here to ask to that has a lot of experience when it comes to these datasheets. I hope you could help me :)

As for the follow up question also
I have this datasheet http://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=1308242_PRD&DocType=DS&DocLang=English where i'm looking for the numbers of durability for the contacts and as I go along comparing this to other datasheets, i find most of relay and contactor datasheets don't have durability data in common or i mean standard.

I would like the image below, the contactor I saw is on Code Y, Ag, 1 pole and it is capable of 50Amp Load Current. I understand that 50A, 277VAC will have a lifepan of 100k (Hz is not rated if 50/60hz, means it doesn't matter because theres a little difference for affecting the number of cycles it could work?). and here i compared that to a 3HP, 240VAC w/c is also 100k cycles. upon getting the ampere equivalent to 3HP, its around 9.3A only so it'll be 9A, 240VAC = 100k right? why is has lower lifespan compared to 50A, 277VAC w/c has more power rate??)

Is there a way to compute if i wanted to know the cycles it could do having 40A, 277VAC or 40A 230VAC (either capacitive/resistive) using the values given on datasheet?? And if 50A 277VAC = 100k cycles, how can i know the approx. cycle if w/ these parameters only 25A 277VAC?? i know it'll be more than 100k cycle but will it double like 25A 277VAC = 200k cycles?

Also, on the same datasheet, it has this section.

so coil for activating the relay does have durability also??

And lastly, if i have a contactor that has 3 poles, does the durability for the contacts applied separately for the 3 poles?? like 100k cycles for each poles? i mean, i had this idea of using the contactor that has 3 poles to use only 1 pole at a time and if it wears-off, i'll just use the other pole instead of buying another contactor. Is that feasible?


texts: Noisy RS485 signal with MAX13487E and Raspberry Pi

texts:
I am trying to use the MAX13487E RS485 transreceiver with a Raspberry Pi 3 B+. I chose this chip specifically because it does not require a RTS signal, which is complicated to setup on the PI. My schematic is the following:

The MAX13487E is a 5V chip so I stepped down the RX signal to 3.3V, but I directly connected the TX line to DI, which I think should be fine because the datasheet states that the input high voltage of DI is 2V.

I am receiving data correctly on the PI, but I can't send anything without the other device rejecting frames because of a noisy signal. Here is a scope capture of the TX line in yellow and the RS485 B line in green. This capture was done without connecting the device to the bus.

And here is a capture of the differential signal (pink curve is A - B):

Should I be feeding a 5V signal to DI or is something else wrong with my circuit?


texts: Soldering Nichrome wire to Stainless steel and steel to PCB

texts: Is it possible to solder Nichrome wire (30AWG) to stainless steel and then the steel to a PCB?


texts: Are the transformers used in switching flyback converters regular transformers?

texts:
When trying to use the turns ratio to assist in the voltage conversion I found current transformers to have the greatest range in N, up to 1:500. Is a current transformer suitable for a flyback switching converter?

Otherwise, could someone please point to a transformer which would be appropriate for this purpose. Thank you!

Looking for one for a traditional isolated 5 V supply from mains.


texts: Can this component be identified? Top mark is 2B with a sideways F

texts:
What do you think, does this look right?
https://www.mouser.com/datasheet/2/916/PMPB215ENEA-1600076.pdf
Short is gone........
This is the 1V rail for a GTX 2060 GPU which is currently shorted. I'm going to pull it and if I can buzz out the traces. Any help would be appreciated. It's marked 2B with a sideways F.


texts: Can I remove my step response overshoot?

texts:
I am working on a balance controller for a robot. I found the open loop transfer function between the motor voltage and robot pitch angle:
G1 =

                    -589300 s^4 - 7.71e08 s^3 - 1.435e11 s^2 - 2.566e12 s - 7.683e09
   --------------------------------------------------------------------------------------------------
   s^7 + 2418 s^6 + 1.317e06 s^5 + 1.977e08 s^4 + 1.312e10 s^3 + 1.796e11 s^2 - 9.658e11 s - 1.525e13

The system has the open loop bode plot and nyquist plot:-

This system has one RHP pole and no RHP zeroes, so it is an unstable system (beucase there are no encirclements of -1). To fix stability while also enhancing the performance I added the following terms to my balance controller.

A negative proportional gain: \$K_p = -1 \$
A post integrator: \$G_{ip} = \frac{0.05s + 1}{0.05s} \$
An integrator: \$ G_i\frac{0.5s + 1}{0.5s}\$
A lead term in the forward branch: \$G_d = \frac{0.06086s + 1}{0.01826s + 1} \$

After adding these to my controller, the entire system is now stable. I plotted the step response with the following code (there is unity feedback):
Gcl = feedback(G1*Kp*Gip*Gi*Gd,1)

The step response has a fast rise time, but about 50% overshoot. The settling time is also fine and there is no oscillations, so I am just looking for a way to remove that overshoot, even if it means a slower system. Is there a way to do that?
Edit
Playing and reducing the gains gives me these step responses:-

Here is the root locus plot of the original open loop system without my terms:-

Edit 2
I added a lowpass filter like Andy suggested, and I hope I did it right, by first finding the closed loop transfer function (there is unity feedback): \$G_{cl}=\frac{G_{ol} \cdot G_{low}}{1+G_{ol}} \$ and it gives me these step responses for different lowpass filters:-


texts: Forward drop of diode vs forward drop of LED

texts:
It is always said that forward voltage drop in the diode is around 0.7 volts. LED also being a diode, why does it have a greater forward voltage drop of around 3 Volts?

What is the model of LED that explains this higher voltage drop?


texts: Android Device Using Buck Converter (Voltage Regulator) instead of Li-Ion Battery

texts:
I have a project that is basically replacing my car's instrument panel with an Android device (a tablet). I managed to make everything work except for one thing: the Li-Ion battery of the tablet was heating up in the hot days (I live in Brazil). The solution that I found was to remove the tablet's Li-Ion battery and try to use a voltage regulator to replace it.

My first try was to use a 2A buck converter to drop the 12V battery voltage to 3.8V and use this as a power supply for the tablet. I managed to remove the flat cable used in the battery and soldered 3 wires (the positive and negative leads plus another wire that is probably a thermitor). Carefully using a multimeter I measured the resistance between the thermistor wire and the negative lead of the battery, it showed up something like 80kOhm. Then I adjusted the voltage regulator for 3.8V, connected the tablet wires accordingly and put a 80kOhm resistor between the thermistor wire and the negative lead.

When I tried to power on the tablet, nothing happened. I then increased the voltage to 4.3V (I read in the battery that I removed that the charging voltage was max 4.35V, so I thought that it was not a problem to try to increase the voltage a little bit) and this time it showed the Samsung logo for 3~5 seconds and turned off.

I was able to boot up the device and keep it running for some seconds with the following: besides powering it using the voltage regulator, I also plugged a USB charger in it. The boot, then, succeeded, it stayed on for some seconds and then powered off again.

Talking to a friend of mine that is an electrical engineer, he explained to me that these kind of devices sometimes have current peaks and that this 2A voltage regulator may not be able to handle the current peaks on GSM bursts and so on.

What I did then was to buy a 12A buck converter with both voltage regulation and current regulation (through potentiometers). Today I tried to use it, expecting it would work, unsuccessfully. I adjusted the voltage to 3.8V (also tried 4.3V as before) and adjusted the current to max current. The same thing happened. This time I used the multimeter to measure the current passing through the tablet and what I got was that when I try to power up it draws something like 200~300mA from the voltage regulator for 3~5s and then it powers off.

If someone could help me figure out why the voltage regulator it not working as expected, I would be grateful.

The 2A buck converter:

The 12A buck converter:


texts: How to calculate the voltage used to light up the emergency light from the given details of manual..?

texts:
I have an emergency light device which is given by a small manual back side of it with some electrical specification. They are:

  Voltage: AC90-240V 50-60Hz

  Current: 0.1A

  Power: 18W

Can I calculate the actual voltage rating of this device?

The device has a rechargeable battery inside it and there is no other informations available in its manual.

When I used the formula:

$$P = V \cdot I$$
$$V=\frac{P}{I}=\frac{18}{0.1}=180~V$$

Is it correct that the device's output is 180V? (I think it is very high and my calculating approach is failed).


texts:
I want to place this XL4015 buck converter board on my PCB.
Is it reliable to mount this module directly above digital logic IC components using spacers? I am not sure if the module has a good ground plane to prevent any coupling.
What are the recommendations that I can follow to reduce the EMI provided that the board incudes an ESP8266 module?


texts: 2 on delay 555 timers in the same circuit

texts: Hello: I am trying to design a circuit in which one LED (D1) turns on after a certain amount of time has passed and then a second LED (D2) turns on after a different amount of time has passed. This is my current circuit and it works well sometimes but seems to falter sometimes. Do I have the correct set up for a my transistor or am I using it in the completely wrong way?


texts: Power amplifier DC and AC current adding

texts:
Here is my simple power amplifier:

I need an explanation how the summary DC+AC current will behave on Probe2 and on Probe3 for positive and negative voltage swing of the signal in the amplifier input? How AC part of the amplified signal affects the Q3-Q4 constant current source DC current value? Up yellow box - Probe2, Bottom - Probe 3.

The output graph: red - output, blue - Q6 base


texts: Calculating actual humidity using sy-hs 220 humidity sensor

texts:
I am getting following output from sy-hs 220 humidity sensor.

466
466
467
466
466

i.e. approximate 466. How would I convert it to actual humidity?
As from datasheet I came to know that this sensor outputs DC voltage. Some calculations are given in datasheet, but I am unable to calculate it.
Link to datasheet Source. (Please see the standard characteristic in datasheet) I am new to this field please help.


texts: How does reverse leakage current of a Schottky diode come into play with a SMPS?

texts: Looking at diodes for a low power switch-mode power supply I'm designing. I'm not quite sure what the reverse leakage current value is, or if it's relevant in the component selection.


texts: DC-DC converter from 5 V input to 6 V with an output current of about 3 A

texts:
I wish to make a DC-DC converter from 5 V input to 6 V with an output current of 3 A or thereabouts using a 7806 regulator or similar. Is anyone able to supply me a circuit. A simple circuit would be adequate with component details/values.

I hope that all makes sense.


texts:
I can't tell how many IO pins that are available on the C8051F975.
SiLabs website, Farnell and the datasheet p. 42 says 19 IO pins, so I guess that is correct, but the according to the datasheet p. 38 there is 21 IO pins.

C8051F975 datasheet

I'm trying to use this MCU in a schematic, but I cannot get it finished before I know which of the pins are actually available.


texts: Which hardware to measure velocity via string/wire wheel attatchment?

texts:
This is a broad question but I want advice on what type of hardware I should look for to make a device that could measure the velocity of an object attached via a string/wire to some sort of rotary wheel.

The purpose of this is to attach it to a barbell and measure mean-velocity for weightlifting athletes.

I'm a software engineer by trade but know nothing about hardware. I'm hoping I can find something that would interface with arduino, as that would ease the learning curve.

As with such a broad question, I'm not looking for a solution, rather I would like to be pointed in the right direction.


texts: PC Mainboard - CMOS Bios Battery Circuit

texts:
I could imagine the CMOS Bios Battery circuits are quite similar on all recent mainboards.

What does it look like and how does it work?

Background:

My mainboard started draining the bios battery (an ASRock H55M).
I inserted a fresh battery with 3.3v. It only measured 2.9V when I removed it, after the PC had been turned off for about 8 hours.
While booting, the BIOS is showing the error message "CMOS Setting Wrong" in combination with "CMOS Date/Time Not Set".
My suspicion is, that the battery voltage - while being drained by the mainboard - likely dropped below the 2.9V and caused the error.

So started wondering what could have failed and what this circuit would look like.