texts:
I am using an ATmega328p to control this RGB LED module.  The ATmega is on an Arduino Uno, but I am programming it in C, without using the Arduino libraries.

To power the RGB module I am also using a 12V power supply.
To power the Arudino Uno I am using the USB power.
I connected it the following way:

RGB LED Module 12V -> 12V power supply 12V
RGB LED Module GND -> 12V power supply GND
RGB LED Module SDI -> ATmega PORTB0
RGB LED Module SCK -> ATmega PORTB1
RGB LED Module GND -> ATmega GND

Now if I send some data R=0xFF, G=0xFF, B=0xFF (Set SDI to 5V and make every second 24 SCK pulses) according to the datasheet nothing happens.
The lights stay off.
But randomly I found out, that if I disconnect the 12V power supply and connected it again randomly, sometimes the Lights turning on in a random color.
So I don't have any clue whats going on.

What can cause this behavior, what can I do to find the error?

    #include <avr/io.h>

// 16ms delay.
static void delShort()
{
    TCCR0B = 0;
    TCCR0A = 0;
    TIMSK0 = 0;
    TCNT0 = 0;
    GTCCR = 0;

    TIFR0 = TIFR0 | (1 << TOV0);
    TCCR0B = (1 << CS02) | (1 << CS00);

    while(!(TIFR0 & (1 << TOV0)))
    {

    }

    TCCR0B = 0;
}

// 1000ms delay.
static void delLong()
{
    for(unsigned char lI = 0; lI < 61; ++lI)
    {
        delShort();
    }
}

static void ledSetup()
{
    PORTB &= ~(1 << PORTB0);
    DDRB |= (1 << DDB0);

    PORTB &= ~(1 << PORTB1);
    DDRB |= (1 << DDB1);
}

static void ledWrite(uint32_t pData)
{
    uint32_t lValue = pData;

    for(uint8_t lIndex = 0; lIndex < 24; ++lIndex)
    {
        if(lValue & 0x1)
        {
            PORTB |= (1 << PORTB0);
        }
        else
        {
            PORTB &= ~(1 << PORTB0);
        }

        delShort();

        PORTB |= (1 << PORTB1);

        delShort();

        PORTB &= ~(1 << PORTB1);

        delShort();

        lValue = lValue >> 1;
    }
}

void main(void)
{
    ledSetup();

    delLong();

    while (1)
    {
        delLong();
        ledWrite(0xFFFFFFFF);
    }
}


texts: Behavioural source output gets distorted when coupled to an active device in LTspice

texts:
When I use a function with a behavioural voltage source to generate a varying PWM in LTspice, I first obtain the clean expected output:

But whenever I couple it to an op amp for instance(as in the below circuit), the output of the behavioural source(you see in blue plot PWM is not swept clean anymore) gets distorted so the op amp output as well. I tried a follower or a voltage dependent voltage source in LTspice or adding series resistances ect., but none of them worked.

Did anyone encounter such issue? This by the way is not about the function I use, I tried with other functions I have the same issue with behavioural voltage source output. Is there a way to stabilize/fix the output?


texts: Analog signal amplification before ADC reading

texts:
I'm working on a system with a distance sensor. As the distance increase, the output voltage decrease. ( Fig. 2 Page 5 : http://www.farnell.com/datasheets/1657845.pdf?_ga=1.97138143.1773643066.1472611965)

Is it better to let the ADC "read" the raw voltage or should I amplify it when the output voltage is too low? (and consider the amplification in software)

Edit :

How is it possible to know the distance when the output is 1v? (Both 2cm and 27cm match with this voltage)

Any idea? Or should I avoid the scenario of a under 10cm distance object?


texts: How do you calculate the random input referred offset of a basic two-stage op-amp?

texts: I have all the mismatch parameters necessary, just wondering where to start. Most documentations I see just teach you how to measure, not calculate.


texts: measurement of output impedance of a CMOS inverter

texts:
I am measuring output impedance of CMOS inverter using ngspice.

No matter how I measure the output impedance, the result can never come any close to the following theoretical calculation if I reduce the value of Rf. Could anyone help ?

https://github.com/imr/ngspice/blob/master/examples/xspice/table/modelcards/modelcard.pmos

https://github.com/imr/ngspice/blob/master/examples/xspice/table/modelcards/modelcard.nmos

ngspice netlist for output impedance measurement

*CMOS inverter

.PARAM V_SUPPLY = 3.3
.PARAM V_OUT = 2
*.PARAM INP_FREQ = '#INP_FREQ#'
*.PARAM INP_PERIOD = '1/INP_FREQ'
*.PARAM NO_PERIODS = '4'
*.PARAM TMEAS_START = '(NO_PERIODS-1)*INP_PERIOD'
*.PARAM TMEAS_STOP = '(NO_PERIODS)*INP_PERIOD'
.PARAM AC_POINTS = 10
.PARAM AC_START = 1000
.PARAM AC_STOP = 1E6

*** *** SUPPLY VOLTAGES *** ***
VDD VDD 0 'V_SUPPLY'
VSS VSS 0 0

*** *** INPUT SIGNAL *** ***
** VSIG IN VSS 0
** VSIG IN VSS AC 1 DC 0
** VSIG IN VSS AC 1 DC 'V_SUPPLY/2'

*** *** CIRCUIT UNDER TEST *** ***
MP OUT IN VDD VDD P1 W=2U L=2U
MN OUT IN VSS VSS N1 W=1U L=2U

** CL OUT VSS 3p
** RIN IN VSS 1G

CIN IN VSS 1E9
Rf OUT IN 1E9
** Lf OUT IN 1E-12
** The input can be either biased with a DC source, or a DC feedback circuit. Using a DC feedback circuit (RC, inductor, whatsoever) makes only sense if there's no DC voltage source, see https://www.edaboard.com/showthread.php?377214-Noise-in-CMOS-Inverter&p=1617292&viewfull=1#post1617292

*** *** ROUT TEST SIGNAL WITH FIXED 1A CURRENT AND VARIABLE TEST VOLTAGE (VOUT) *** ***
*VOUT VOUT 0 'V_OUT'
*** *** IOUT flows into the output of the circuit under test, so negative terminal node of this current source is OUT instead of VSS
IOUT VSS OUT AC 1

*** *** ANALYSIS *** ***
*.AC dec 'AC_POINTS' 'AC_START' 'AC_STOP'
*.TRAN 'INP_PERIOD/1000' 'NO_PERIODS*INP_PERIOD'
*
*.PROBE TRAN V(IN)
*.PROBE TRAN V(OUT)
.OPTION POST PROBE ACCURATE
.include modelcard.nmos
.include modelcard.pmos

.control
*AC dec 'AC_POINTS' 'AC_START' 'AC_STOP'
AC dec 10 1000 1E6

let ROUT=OUT/abs(i(VSS))
plot ROUT
print ROUT > ROUT.log
.endc

.END

ngspice simulation result = 60 kilo ohm

ro_p theoretical calculation for PMOS

ro_n theoretical calculation for NMOS

ro_equiv Output impedance calculation of CMOS inverter = 56 kilo ohm


texts: What are limitations of visually simulating/prototyping microcontrollers?

texts:
I am thinking of writing a windows applications (similar to Proteus ISIS) to simulate/emulate a specific PIC24 Micro-controller  of my system and peripheral components used like Segment LCD and  a external voltage generator for ADC to start with- which can be drag and dropped and connected electrically .Thus By dumping a hex file in program, I can visually prototype my small board.  My need may be similar to PICSIM -

What are the limitation of simulating (and emulating) a Micro-controller based system in Windows machine by such software?  Is there any limitations while visually modelling a micro-controllers by its datasheet?
I found there are no simulation models for 32bit pic micro-controllers in Proteus.  Is there any limitation to model 32bit Micro-controllers?Will there be any performance overhead in windows or on processor?
Does using GUI frameworks like .NET will be a performance overhead?  Is it better to write on C++ to avoid any overhead?


texts: If a short circuit occured across the mosfet would anything happen in this scenario?

texts:
I am just confused about understanding a simple concept.

For the following circuit:

Say the blue line acts as a short for whatever reason. If the LED has a forward voltage drop of 23 V and forward current of 30mA (LED contains everything it needs for this example (as in resistor is inside just for this example))

If we don't have a resistor and just a wire connecting the MCU to the mosfet, when the short occurs will the current still remain at 30 mA? As in the current would not become infinite/very large? Essentially nothing will change except the current will be continuously entering the MCU pin and could potentially blow teh MCU if the 30mA exceeded its rating?

In short:
Essentially I just want to know that if a short occurred over the mosfet and say the MCU pin was low for that state, will the current remain the same at 30mA due to the limiting resistor of the LED. As in that's all that would happen (and obviously that the MCU will always have current going into it)


texts: Highly accurate CMOS Squave wave clock signal to drive MF5CN Audio filter

texts:
The task is to generate a CMOS (+-5[V]) square wave signal with 50% duty cycle in order to drive a second order active filter IC (MF5CN) with variable or fixed frequencies of 150[Khz], 300[kHz], 750[kHz] and 850[kHz].
This clock is to be powered from a signle power supply.

THe problem is that the more "clean" (accurate) the square signal is, the better the performance of the filter (more accurate at the cut-off frequency)

I've already tried the HEX inverter using the HD74HC14 circuits but at the listed rate of frequencies there is a lot of distortion, so ¿How can I reduce or to "clean" this signal in order to make it as much accurate as I can?

The DDS aproach would be an option but it would be way too much of an overkill, and in fact a much more complicated project than the one I am trying to accomplish now.

As soon as I can post a picture I'll upload the screenshot of the scope.

Other methods to generate the said signal are also welcome as long as it is the more cheap and it does use the less components.


texts: Rotor current paths and lamination in an induction motor

texts: As far as I understood, the rotor currents circulate through the aluminium bars embedded inside steel laminations. But why do they use steel for laminations instead of an insulator if the the idea is to loop the current only through the bars?


texts: UART receive only works if I have a oscope or voltmeter attached to it

texts:
I designed a board to interface the CEL MeshConnect Mini Zigbee module with a lighting controller board.  The Zigbee module is able to transmit bytes via UART and I've verified this, but the radio does not receive a response unless I have my oscope or voltmeter probe attached to that pin(and the ground reference of course).

Does this mean I have a grounding issue?
Has anyone ever seen this happen before?


texts: How to correctly simulate Zero Cross Detector Circuit?

texts:
I am trying to simulate a circuit for Zero Cross Detection. The end goal is triac phase control. My simulation using proteus hangs up and with message "Simulation is not running in real time" and proteus freezes untill crash.

For the ZCD Circuit, I referred to the following post.

The circuit i am trying to simulate is this

Simulation screen shot:

Is there anything wrong with the circuit or am i not simulating it right?

Please advice.


texts: Obtaining noise spectral density of OP-AMP from Peak to Peak voltage

texts:
I'm in need of a low offset opamp for integrating purposes, I also need it to be very low noise since the output of the opamp will go into a 3000 V/V gain stage.

The opamp that seems to satisfy my needs for low noise for the 3000V/V dual stage is: AD797 while the one that satisfies my low drift requirement is this: LTC1151

However when looking the datasheet of the LTC1151, I could'nt find the noise voltage spectral density, instead theres a volts peak to peak figure of \$ 1.5 \mu V_{p-p} \$ from 0.1 to 10Hz.

So my logic is that to get the noise voltage density I just need to divide by two (to get the peak voltage) and then divide by \$ \sqrt{10 Hz} \$, but im getting  \$ 237.2 nV/\sqrt{Hz}\$ that seems too high. Is there something wrong with my calculations? Or is the voltage so high because its a zero drift op-amp? Im also aware that the 0.1 to 10 Hz voltage spec is mostly due to 1/f noise and not white noise of the opamp.


texts: Determine voltage drop over 10G resistors with cheap multimeter

texts:
I have two 10G resistors connected in series with a 3V battery. I want to determine the voltage drop across one of them, which of course is 1.5V. When I use my multimeter to check the voltage drop, it reads ~3mV, which I believe is because it has a 10M impedance so the circuit is really one 10G resistor in series with (a 10G resistor and a 10M resistor in parallel), so the voltage drop when the multimeter is part of the circuit is 2.99 mV.

simulate this circuit – Schematic created using CircuitLab

How can I measure the voltage drop? Is there something I can build so that that I can adapt the multimeter impedance to be high enough that it won't affect the circuit as much?


texts:
To be more precise, I'm interested in the amount of "created" heat during normal operation from a diazed 16 ampere fuse.

How hot will the fuse be after delivered 16A in seven hours with the voltage of 230VAC, in a nominal environment of 30C.


texts: Swinging of Output Current from voltage controlled current source

texts:
I am learning different voltage to current converters during my bachelor thesis which are a composition of OpAmps and Transitors. The following structure is quite interesting for my thesis and I want to learn it by heart.

In this topology, I can see that if feedback is taken from Emitter to Inverting terminal of OpAmp (with +6V grounded), the output current seems quite stable in simulation and control seems very simple and also that the output voltage of OpAmp is Vbe higher the input voltage in case Rf = R1 (I would appreciate if i would know the disadvantages of that structure).

However, in case if feedback is picked from collector of transistor, as is shown here, the output current Ic is not stable anymore and there is continuous swinging on output current. I can't understand why does this happen. This was already discussed in What does this op amp/transistor circuit do? (revised circuit) from Andy Aka, according to him it happens because of OpAmp gain coupling with Collector gain of transistor which causes it to swings. I need more analysis in this direction- and will be very grateful if someone can suggest any literature on this swinging effect where I can learn it into details !

Secondly, the other problem with this topology is that if my emitter resistance is not constant and is rather a value within a given range calculated for this design, I can't directly calculate the output voltage of OpAmp as compared to former case wehre output voltage is simply input voltage plus Vbe. Is there any other way to calculate output voltage of OpAmp (Base voltage of Transistor) without knowing exact emitter resistance ?

Thanks alot for your answers !


texts: Estimate the phase margin of a loop gain

texts: The loop gain is \$10^6 /[(s+1)(1+s10^5)]\$. Below I have the Bode plot. How can I derive the unity gain frequency from the Bode Plot? How can I find the phase margin from the phase plot of the Bode?


texts:
I have designed a PV system which like conventional systems has a Boost converter followed by an inverter. The output of 230V (AC) is achieved for irradiance of 1000 W/m2 to 600 W/m2. However, after that from 500 to 200 W/m2, the system has to be overmodulated which should not be done to get the required output. Simple duty cycle variation is not working for the lower irradiance levels. Please suggest how to fix this problem.

Thank you.


texts:
I would like to design a power supply to a micro-controller based system that will need a 12V as Vin and 6A to feed the whole circuit.

The system is expected to be an alarm small equipment.
It is expected to work for a whole day.
It will have a battery charger controller (Icharge=2A) with a battery pack.
Sensors.
LCD.
Two actuators (draw around 3A.)
The system will be feed from a main line of 230Vrms and 60Hz line frequency.

I have decided to use a CCM flyback converter to step-down the input voltage to 12VDC. I found this topology to be very easy to design, more practical and well used in many AC/DC converters, but when I come to power factor correction, some questions have been raised in my mind:

In my case, with a 72W power needed for the system, do I need a PFC to optimize the power consumption, or I can connect the flyback directly to the main line?

In case it is better to use a PFC (as I expect,) how do I choose a better solution (topology?)

From what I have read, the most used topology is the critical or borderline conduction mode boost converter.

How do you qualify this solution to my requirements? Is it the best one or I should select another solution?

What criteria will help me to decide which topology suits my design?

Since this solution steps-up the voltage, will it not affect the efficiency of the downstream converter, since it will step it down again to 12V?


texts: Induction coil/furnace specifications for heating small Pt crucible to 1400 °C

texts:
We are exploring the idea of using induction to heat up a small platinum crucible (height x diameter x wall thickness is 20mm x 6mm x 1mm) to 1400 °C in vacuum. The Pt crucible will be placed in an evacuated quartz tube of c. 20 mm o.d., the entire assembly is then placed in the coil. The heating should be stable (say ±50 °C) for at least 30 minutes.
Induction is a new field to us. Which specifications of the heater would you recommend for this task? (e.g. frequency, current and other important things I might be missing).
So far it seems that a 1-2 kW machine with a frequency between 100 and 500 kHz could do the trick. Due to chemical constraints in the experiment, the frequency must stay less than 1000kHz. We're happy for any input that get us on track. thanks!


texts: How do I determine the purpose of this op-amp circuit?

texts: I have this circuit and I was asked to determine V2=f(V1) and V3=f(V2) which I determined below. The next step is to figure out what the purpose of this circuit is but I'm not sure how to do it from the equations I got.


texts:
I'm trying to put together a Near Field sensor where the pcb antenna can be remotely installed  (about 2 ft away). I've looked at NXP PNxxx design here ---  http://eng.utah.edu/~mlewis/ref/NFC/AN1445.pdf

However, the designs in this document have their host interface and antennas immediately next to each other on the same board. I'm trying to separate the antenna and host interface (PNxxx w/ matching circuit) and connect these via a wire/cable so that I can place the antenna in another location. I was thinking of using two 24 AWG wires as a cable with a simple two-pin interconnect, but I'm worried that this has impedance implications.

Should I use this approach or a coaxial cable instead? Or on the whole is this a bad idea?


texts: Overshoot and undershoot on clock signal missing in high frequency(HyperLynx)

texts:
I'm using it for my work in Hyperlynx SI to test high-speed signals.
This is a general question but I read somewhere that the simulation in high freq could make a problem to identify some peaks in signals, and this is true in my case.
When I tested the signals in 250Mhz oscillator the signals look good without overshoots and undershoots,
and in 25Mhz I saw the overshoots and undershoots like this:

I want to know why it happens?
what are the physical explanations for this phenomenon?
Thanks!


texts:
I am trying to analyse a 555 based timer circuit:

My current understanding of the circuit is that the output is changed by the voltage at pins 2/6 (let's call it V). If V drops below 1/3 Vcc, output is set high and if V gets greater than 2/3 Vcc, the output is set low and the discharge pin is open to ground.

The timing is provided by charging/discharging C3. The charging is done through the R1/RV2 pair and discharging through R2/RV1 pair.

Now, my questions related to this:

What is V at the time the circuit is connected to supply? To me, it seems like it's floating without a reference voltage, since C3 is empty (i.e. basically open circuit) and D2 does not conduct since OUT is low. (I am pretty sure I am wrong here, but I don't know why/where).
How to determine the period and the duty time? (I am looking more for a formula and some pointers to understanding its derivation)
The examples of 555-based timers I have seen around usually charge C3 from Vcc. In this case, it is charged from the output pin. Are there any advantages/disadvantages of this approach?
What is the role of D1?


texts:
I'm trying to do a problem for class and I'm having trouble on clarification and where to start.

I understand how the turns ratio works, but I don't know how to find it here.  I can't find anything in my book or in handouts; I only find them when there are resistors on both sides.

I'm also confused on what VL and Vp are.  I think Vp is the peak of the whole wave but I don't know what VL is showing here.  Vrpp is also confusing me.  I just need some clarification and guidance.

Thanks


texts: Logic level shifting from 5v to 2.8v and vice versa

texts:
I need to use a logic level shifter in my circuit which translates 2.8V logic level into 5V and the other way round. I found this document. The device itself is presented on the page 10. It is very simple and consists of one mosfet and 2 pull-up resistors. However there is one catch. To use this device I need to have both 5V and 2.8V power supplies in my circuit. I only have a stable 5V line.

What would be the easiest way to solve this issue? I thought I could connect 3 diodes in series, which would drop the voltage about 3*0.65V = 1.95V, so I would have 3.05V left, which is a bit too high, but I guess it would work. But maybe there are easier ways to shift logic levels?


texts:
I am trying to learn about STM32 programming. I started to read some references before start the programming.

I am currently reading this ST presentation.

It says:

  When an interrupt request with lower or equal priority is
  raised during execution of an interrupt handler, it
  becomes pending. Once the current interrupt handler is
  finished, the context saving and restoring process is
  skipped and control is transferred directly to the new
  exception handler to decrease interrupt latency.
  So back-to-back interrupts with decreasing priorities
  (higher priority values) are chained with a very short
  latency of a few clock cycles.

What is the context saving and restoring process mentioned in the above quoted text?

If someone can explain entire STM32 interrupt process, greatly appreciate.


texts: how to turn only one led (from a bi-colour led package) ON at a time by using a mosfet

texts:
I have designed a circuit to turn green led ON if the voltage from the power supply (3.3kV 10uA) is greater than 2.7kv and turn the red led ON if it is equal to or less than 2.7kV.

Here 50Mohm and 50kohm is a 4pin caddock HV divider resistor. 100kohm resistor is used in order to drop the 2.7kv to 1.8v so that it turns off the mosfet. The led that i thought of using is a bi-colour common anode red+green led. One point to be noted is that the 12v is from the same power supply and this is converted to kvolts.

The problem with the circuit is that when I set the voltage between 2.708kV and 2.35kv both red and green leds turns ON. Please guide me how can I solve this issue and also can i use bjt instead of a mosfet.

Thanks in advance.


texts: Why did sparks fly when testing outlet frequency?

texts:
I'm using a multimeter (Mastercraft 052-0052-2) and I decided to see if the frequency of an outlet would read 60hz. I switched my multimeter to the FREQ setting and plugged the RED test lead into the NEUTRAL of the outlet. Upon doing this, a loud bang occurred with a huge spark. Yet the outlet still works and the breaker did not trip. Could somebody explain to me what may of occurred?

The multimeter works fine and no fuses were blown. The BLACK test lead was just resting on the carpet floor. (It probably didn't touch the carpet though, since it the metal probe sits 2cm above the carpet.)


texts:
im a beginner at electronics.
im trying make an drawdio circuit with the instructions in the link below:
http://www.ladyada.net/make/drawdio/drawdio2schem.png
i have following components on the circuit.

NE555N 555 timer
PN2907 transistor
100uF 25V capacitor (instead of 6.3v one on the ladyada's page)
680pF ceramic capacitor
0.1uF non-ceramic capacitor ( instead of ceramic one on ladyada's page)
1/4W 5% 10 MEGAohm resistor
1/4W 5% 10 ohm resistor
1/4W 5% 300K resistor
Small 8ohm speaker 0.5w

do you think any of those changes i made might be causing low sound problem??
please help :/


texts: MCP2551 sending with 4V differential voltage

texts:
I'm working on a CAN Bus Module with ATMEGA328P, MCP2515 and MCP2551. In my test setup, I have the module connected to a Raspberry Pi with a CAN hat.
The communication works in general - both nodes receive and decode the messages of the other node just fine.
After hooking up a scope to the bus, I found that my module seems to send with 4V differential voltage while the raspberry sends with 2V as expected.
CAN part of my schematic:

A message sent by the Raspberry Pi (differential measurement):

A message sent by my module:

The pink channel shows the voltage on the MCP2551's VDD pin between 4.9V and 5.2V - although the level is not totally smooth, it should be well within the supply voltage limits of the MCP2551)
Termination is 120Ohm on both Raspberry Pi and my module.
Any hints on why the MCP2551 in my module is sending with twice the expected voltage?


texts: Is the sun enough to power all of our needs?

texts: If so why isn't solar power being implemented more so? I don't mean to as a govt conspiracy post. But what's holding us back from achieving this, if it is indeed possible.


texts: Determining which fuse to use and where to put it

texts:
I've been working in my thesis project which consist on a PID controler to mantain a certain temperature in a case. The heater module is made of two 40W-12V 3D printer resistors and one 15W-10 Ohm wirewound resistor. In addition to these, I have an Arduino Uno, a 20x4 LCD screen, two temperature sensors and two PC coolers (2W each) which all sum up in 5W (rounding up). I'm using a 12V-10A switching power supply.

When the PID is at 100% the tension in the resistor (Rparallel= 1.5 Ohm) is supposed to be 12V, but due to the cables and transistor (IRF540N) drop, the maximum tension is 10V. So, all in all, in maximum behaviour I would be drawing 66.6 W + 5W= 71.6W.

My problem is that I want to be sure that the system can work for a long period of time without overheating/exploting/breaking. My question then is where and which fuses should I use?

In the following picture you can see a section of my board, more specifically where the power supply and heater module connects to the board. In total I found 3 places where heat gets high: power supply connector, heater module connector and power supply (switching) case. I have one cooler flowing air to the transistor and the power supply connector but I don't know if that's enough.
The 3x2 connector datasheet is this

I was then wondering, should I only use one 10 A  cartridge fuse right after the power supply ?Where? Should I add a thermal fuse somewhere near the transistor? How can I ensure that the device can work for a long time?


texts: Has anyone tangled with the B6284 boost converter IC? It has an enable line that is supposed to shut down the device when connected to ground but I can only get it to drop the output from 12 V to 3 V. Seems bizarre for something as simple as a control pin not to work as advertised. Wondering if I'm missing something?


texts: Minimum filament/heater voltage for Valve/Tube amplifiers

texts:
What is the minimum voltage I need to provide my tube to be able to produce some sound?
I am trying to debug my first tube amp, but I can only power it with a 11,8V supply instead of the recommended 13,3V.(PCL86)

Could it be that the triode and pentode doesn't open because of this?
Or in an other way: What filament voltage do I need relative to the recommended one to be able to use a tube?


texts:
So I'm new to servomechanisms and am initially unclear on 2 things.

For a control transmitter, I know that it converts the shaft position to an electrical signal. How exactly does it do that?

If this signal were to amplified, how is the control transmitter connected to an op-amp?

Any explanation would be appreciated


texts: Problem with circuit created with fabric pressure sensor

texts:
This is only my second time working with any type of circuitry, so I apologize in advance if I don't use the right terms when I explain my problem. Feel free to correct me!

So in one of my projects, I used this instructable to create a pressure sensor out of conductive fabric. I followed the instructions and the sensor worked flawlessly. I actually want to do this on a larger scale. But of course, I'm testing this small version first before I move on to a big piece of fabric.

When I tried setting this up with an Arduino Uno (Uno is for testing purposes, I'm actually going to use a Lilypad), I was able to create this exact circuit, send light to the LED, and output the resistance value onto the Serial. But for some reason, when I remove that LED, it looks like the connection going into the Arduino, sending the resistance information, won't go through. You can take a look at this picture** to see what I mean. I also tried connecting the power to the pressure sensor and then connecting the output straight into an Analog pin on the Arduino. Even though this exact thing works with an LED attached and outputs the resistance value to the Serial, it doesn't work without the LED.

On a side note, I was wondering if anyone knew if I made this on a larger scale, using a lot of conductive fabric, if it would affect the resistance and the results of this project in any way?

**The picture shows the power going into the fabric from the Arduino through the green wire on the right side. On the left, the long red wire in the return going into the breadboard. The black wire from the breadboard is pinned into Analog0 and the shorter red wire is connected to GND.


texts: How can I choose a MOSFET based on Rds? I have understood all the parameters except this

texts:
I have understood all the parameters except Rds and conduction loss. Please explain them to me.

I am using a lithium-ion battery pack of 36 V and its maximum voltage is 42 V to drive a motor.

Motor specifications:
Minimum current: 500 mA
Maximum current: 15 A
Ipulse: 30 A

The MOSFET I am planning to use is the Vishay SQD50N05-11L

MOSFET specifications:

So based on the above specification, I have calculated the power dissipation:

Power dissipation: I2 * Rds = (15 A)2 * 11 mohm = 2.47 watts

And the maximum power the transistor can dissipate without a heat sink:

(Tmax - Tambient) / R(jA) = (175 °C - 25 °C) / 60 °C/W = 2.5 watt

I am confused that how to check and relate the power dissipation with Rds and select the MOSFET based on it. Is the MOSFET that I have chosen okay, based on the above specifications or should I go for a MOSFET with a low Rds?

And please explain how to select the MOSFETs based on Rds.


texts: Best topology for an AC/AC switched-mode power supply

texts:
I need a power supply with two 100W isolated AC outputs. The output voltage must be a 24V 10kHz sine wave. The load regulation is not so important, what is truly important is the preservation of the sinusoidal wave shape under both rated load and no load conditions. Which SMPS topology is best suited for this purpose?

The first thing that came to my mind is an AC/DC SMPS (PFC + isolated step-down) followed by a PWM inverter. But I think that it is over-complicated for such a seemingly simple task.

The second thought was to get rid of the inverter. Indeed, we already have a rectangular AC voltage after the step-down stage. Maybe we can filter it instead of rectifying? I also found information about resonant converters, and that they can be used as AC/AC converters.

So what do you think about it?

Some additions

The input is 230V 50Hz mains.
Load regulation: 20% is OK.
The same with THD: 10-20% is OK.
I'm sorry. I forgot probably the most important thing - efficiency! It should be at the level of an average SMPS, 80% or more.


texts: Servo accelerometer dual power rail requirement

texts:
Why does this type of accelerometer need split supply. In the data-sheet this is described as a excitation voltage. But the diagram they provide does not show any +/- rails or any excitation Wheatstone bridge ect.

I cannot find any illustration about this type of accelerometer. And their data-sheet is not clear as well.

How can we illustrate this type of accelerometer along with their +- power/excitation connections? What is being excited here? Are +- power inputs supply anyother unit besides the opamp rails?


texts: Two PNP Transistors - Jumper Collectors with Emitters and Bases at Same Potential?

texts:
In the attached image, OUT1 and OUT2 are logically identical (provided for redundancy).

I'm wondering if it's valid for OUT1 and OUT2 to be tied together and brought across a single load? This is necessary due to cable constraints.
My electronics knowledge is very rusty so any advice is greatly appreciated :^D
EDIT - Sorry for lack of info! The "load" is a 24V sinking input terminal of a programmable logic controller (PLC) whose purpose is to provide a ground path and read the received voltage as "high" (~24V) or "low" (~0V). I would imagine for theoretical purposes this could be looked at as a purely resistive load but to be honest I'm not 100% sure.


texts:
I'm trying to sum two audio signals that zero at different voltages.  One DAC outputs with a zero at GND (0V).  The other (bluetooth module, Microchip BM62) has a virtual zero at 1.4V.  I'm trying to sum them to drive a differential input audio amplifier (Maxim MAX98400AETX+).  It's been quite a long while from my time with opamps so I tried passive summing with 4.7K resistors on each output and taking that output to the positive input on the amplifier then connecting the (-) input on the amplifier, DAC ground, and Bluetooth Line out Ground all to common ground and I get very low sound from the bluetooth module output.  With each singularly connected to the amplifier, the sound is great from either device.  Can someone point me in the right direction?  Both signals are mono.

The signals both do not exceed 2.5-3V.  I have 3.3V, 5V, and 12V at my disposal.

Thanks!

Edit:
Here is a schematic of what I'm trying to do:


texts:
I'm reading the datasheet but not sure if battery charger, charge the battery up to natural value 4.1 Volts, using the lowest V input threshold 3,5V.
A typical application says 4,5v but can the IC charge the battery in natural charging mode (4,1V) using as input a voltage low as 3,5V?

From the Datasheet:

  "Differential Undervoltage Lockout. An undervoltage lockout circuit
  monitors the differential voltage between VSYS and BAT and shuts off
  the charger if the BAT voltage reaches within 50mV of the VSYS
  voltage. Charging does not resume until this difference increases to
  145mV."

As it says, if input voltage is 3,5V then my battery charging up to 3,5V. Right?

TLC4040


texts: How to solder WS2812b LEDs(individual,not a strip) to a PCB?

texts: I wanted to do a project using these ws2812b leds, and I find them nearly impossible to hand-solder them because of the tiny contact points. Can someone teach me how to solder these by hand? They are surface mount components as you can see in the images.


texts: PTC thermistor vs. NTC thermistor for measuring the temperature of a liquid

texts: I have to measure the temperature of a liquid. Does a PTC thermistor has any advantage over an NTC one? I mean, are there conditions where one is preferred over the other?


texts: What is the difference between different types of GND

texts: I would like to know the difference between different types of Grounds like AGND, SGND, Battery Gnd, PGND. Are all the grounds not same? Cant we connect the device to any one of these grounds?


texts: Wireless Power Transfer for a toothbrush

texts:
The general idea is to charge a cordless toothbrush from 12V DC, instead of the mains. I have used a simple circuit that I more or less lifted from a Linear AppNote/Demo manual (DC1969). I would like the circuit to be as simple as possible. The actual transmitter is below, what is not shown is a simple timer that shuts off the thing to conserve power after say 2-3 hours. (The time normally taken to charge).

I wound a pickup coil with 100 turns and that produced 6V pp 32kHz on the original mains charger. The idea is to create something that produces the same voltage. A 270uH coil (100 turns on the ferrite salvaged form a broken charger) needed only approx 8V to produce 6V so I thought: Transformer, decrease number of turns, but that actually increased the voltage on the pickup coil :) In fact, lowering the inductance of L3 and adjusting C3 increased the current in L3 which naturally will give a higher voltage in the pickup coil.

Now, I am not 100% sure why, but there is a recommendation that L1, L2 should be 5x the inductance of L3, which is clearly not the case here. The purpose of L1, L2 is to act as reservoirs to make sure the circuit acts in current mode, right?

Question is: Is there an optimal way to size L1, L2, L3, given a V1 of 12V? The citcuit works fine now, idle consumption is approx 150mA at 12V, ie 1.8W, whereas the original charger has an idle consumption of 1.2W.

Enquiring minds want to know.

Edit: Based on comments by Russel (below) did I try a centre-tapped coil. This is the waveform with the original circuit.

and this is with the centre-tapped version. The idle current draw fell from 0.14A to 0.05A, yay!

Too bad I already ordered prototype PCBs, but I guess that is why there are x-acto knives :)

Prototype to give you some idea of the coil sizes. The ferrite is from a scrap brush, but there is one from Amidon that should work quite nicely. The innards of a scrapped brush is in the background to give you an idea of what the original pickup coil looks like.


texts: Parallel Caps as a Bipolar (twin polar in combination)

texts:
So, I saw a similar question about 2 caps in series to make a bipolar.

Lets assume polar electrolytics
I pretty much "get" electronics and build stuff - it works as I expect mostly.
I have a penchant for making mistakes and just wanting to see

So a speaker I was reconditioning had a BP cap electrolytic between it's tweeter and the parallel speaker wiring. I wanted to replace it .. was a 2.2uF cap. Instead of wiring the two negative terminals together and using positives for either end of the new combined thing I wired them so negative to positive and  thus they are in parallel but one in each direction. Why? I'd rather have a higher than lower capacitance and ... anyway it works and sounds just fine. I assume its a C1+C2 combined capacitance. (I used 2 matched 2.2uf) However ... maybe one of them rejects part of the flow as it is backwards to the source of power or + (yeah I know electrons go towards + but - is heading to earth in this amp so ..)
If there is reverse flow (and yes it would wouldn't it because it's Ac) then maybe that cap then readily lets it pass?
So two caps in parallel but one is backwards polarity - is this just another way to make a BP style cap.
It seemed contentious on the previous article - some said, "no that will blow up" and others said "that's normal, that's how BP caps are made" when referring to the series with negative terminals together wiring.
So the upshot is that if they are in parallel but one is rejecting flow in one direction then do they actually act as a 2.2uF rather than 4.4uF working as a pair? Note, its been working fine for some time now ... so I'm guessing that no, I'm not an idiot. [Yes, I often do idiot things]. Thanks for educating, trolling or any other related ways to calculate how it would be.
What happens exactly to reverse current across a cap because you can couple AC and it passes through and people use polar electrolytics for that ... maybe they shouldn't. I do - in preamps have plenty of polar electrolytics coupling audio signal albeit line level or less - not power to speaker. Some audio power amps running with asymetric power supplies have a big cap in series with the + end to the source and the - end to the speaker. Thus I'm assuming that even a single cap isn't that easy to blow working with an AC if it doesn't exceed spec.


texts: Ceramic caps vs electrolytic. What are the tangible differences in use?

texts:
A quick google around and all I seem to be able to find are people talking about the physics & the chemistry of the capacitors but not how this affects choosing which to use.

Avoiding talking about the difference in their make-up, and the larger capacities found in electrolytic caps, what are the main thoughts that drive which type of capacitor to use for an application?

For example, why do I see it suggested to use ceramic caps for power decoupling per microprocessor & a larger electrolytic capacitor per board? why not use electrolytic all around?


texts:
I'm trying to set up my first project on an STM32F4 and I encounter a problem which consists on how to pass the measures I took from the MEMS accelerometer from the STM32F4 to the computer.

I'm using the IAR workbench as a development environment.
Can you help me please?


texts:
I'm new to this forum and I am trying to find a solution to control three small electric linear actuators I have made for my RC controlled model aircraft, they have mini 6 volt geared brushed DC motors driving a nut on a threaded rod with thrust bearings to isolate any loads to the gearbox and motor shafts, I have tested these many times in both directions and they work well without any binding.

I am a retired mechanical engineer and can handle the mechanics but require some help on the electronic control for these units, I have researched several sites, but at present have not found a complete solution.

My goal is to go all electric with this model aircraft, regards electric retracts and replace the retract servo's that would normally operate the doors, with these mini electric actuators, the servo's that normally operate the doors have a feedback from a potentiometer, the actuators I have made are too small to incorporate any feedback signal so I assume would need some form of over-current trip when reaching the end positions, and H-Bridge to reverse polarity.

The sequence required would be:

Doors open x three actuators operate and stop motors
Change polarity for next action.
Retracts down x three actuators and stop motors
Change polarity for next action.

Control to be on one channel retract switch on TX.

I'm not sure if an Arduino with motor shield could be programmed for this, as I have no experience with programming any type of micro-controller.


texts:
I am building a small smoke machine using a vape pen atomizer as a base and connecting a small aquarium air pump to force air past the heating element in the atomizer.
I want to be able to control the atomizer's heating element with an Arduino Micro (3.3V version running at 8 MHz) PWM output. For this, I figured I needed a MOSFET.
I am no electrical engineer and I have been reading up on the characteristics of MOSFETS. With this information I concluded I would need a N-channel enhancement MOSFET with a low VGs(th) so that I can control it with the 3.3V PWM ports, and a minimum ID of ~3A so that it can drive the heating element. I settled on the IRFZ44N, now the question is am I correct in this assumption? I am uncertain because these MOSFETs have so many characteristics that I believe I am missing something important.
Technical details:

Everything is powered by a 1S 3.7V 4200 mAh Li-poly battery (26650 form factor)
The heating element is a spiral with a resistance of 1.6 ohm running on 3.3-4.2V (based on battery charge) at 2.1-2.6A


texts: Why duplex lap winding has twice as many current paths as simplex lap winding?

texts:
I found the statement of question on page 346 in the book "Electric Machinery Fundamentals, fifth edition" written by Stephen J. Chapman.
When I searched for how duplex lap winding looks like, I found the figure in this link: https://circuitglobe.com/lap-and-wave-winding.html#:~:text=The%20duplex%20lap%20winding%20is,number%20to%20the%20second%20winding, which is also cited in this thread: DC motor armature rewinding.
However, it seems to me the figure shows that the number of current path is the same as the simplex lap winding but with twice the length of current path. Why the number of current paths in a DC electric machine is m * P, where m means m-plex, P is the number of poles on the machine?


texts:
Please help me to identify this 10-pin SMD IC with top marking MMAB GA9. On the back side there is no code.
My search on several SMD Code Web sites was unfortunately not successful.
The slide gauge below is metric [mm]. The plastic body is 3 mm x 3 mm.


texts: Power loss due to EM radiation from electric power transmission lines

texts:
Power lines also radiate em waves:

And the radiation should cause some energy loss.

How can we deduce logically whether the radiation loss for 50/60Hz power transmission lines are negligible? I know in low frequencies the loss is less but in this case the lines can be too long upto 2km. Is there a way to simplfy this and formulate the radiation loss roughly? Should we start modelling it like a 60Hz 2km dipole antenna?


texts: How to count the number of objects in a bottle?

texts:
I am working on a pet project using arduino where I need to keep track on number of objects in a bottle.It requires counting the number of objects(size of a regular pill and approximately of the same weight). My approach to this was asking the user to drop one object into the bottle and weigh it, then ask the user to drop the remaining objects into the bottle. So I can find the number of objects using the formula (total weight)/(weight of single pill).Whenever the weight of the objects in the bottle changes the formula is used and number of objects still in the bottle are found out, as you can see this is not very user friendly so I was looking if anyone can help me out with a better solution.

EDIT:If not by using weight is there any way to count the number of objects by using IR sensors etc., cause I have seen the load cells to measure small cells are quite expensive.


texts: E-bike battery needs custom charge voltage, but how?

texts:
I thought I'd give my old e-bike an upgrade, and I've build a 8S4P battery with charge controller (BMS). The thing is the electronics of the ebike quite working @ 31.5 V - a fully charged 8S battery is at 33.6V.

At first I thought I could throw away the idea, but when I found out it works as long as the battery stays below 31.5V I thought let's take an old laptop adapter (19V) and a 200W step-up convertor and make custom charger.

It didn't work out well. It works a couple of times, but then the laptop adapter breaks. Also the step-up convertor makes weird noises while charging.

I read somewhere here even with BMS you can't use a laptop adapter because they aren't CC-CV.. So I need some suggestions on how to make a charger that stops charging @ 31.5V.

What if I buy a step-up convertor with adjustable voltage and adjustable current, would that solve the problem?

Or what if I buy a 10S 42V lithium charger and use a step-down to get down to the desired voltage?


texts: What is Verilog Output (.vo) file? When it is created?

texts:
I was running PCI Express reference design simulation in Modelsim. Compilation failed and an error "cannot open top_core.vo file in read mode" was displayed. I went through respective folder, but that particular file was missing. A verilog file with same name (top_core.v) is there is same location.

After going through all the document what I understood is, verilog output file is created by Quartus II when compiled. Then why it is not happening in my case. Is there any other method to make top_core.vo from top_core.v file ?


texts: Selecting the right ferrite core for high currents

texts:
I need to design some \$3.7 mH\$ coils for two low-pass filters and a \$5\mu H\$ coil for a boost converter. But am having some trouble finding suitable ferrite cores, since there will be a significant amount of current running thru all of them. So I thought I'd ask here for some guidelines about calculating and choosing the right ferrite cores for my applications.

First, I am aware of the equation: $$B=\mu_0\times\mu\times\frac{N\times I}{l_e}$$ where \$B\$ is magnetic field strength, \$N\$ is number of turnes, \$I\$ is current thru the coil and \$l_e\$ is effective length of the core.

However I was suggested by an employee at one of the company that produces ferrite cores, that whilst this is a valid equation to use, for high flux densities I am better of using one of these equations: $$U_{rms-sine}:=B_{max}\times A_e\times N\times f\times\pi\times\frac{2}{\sqrt{2}}$$ $$U_{rms-square}:=B_{max}\times A_e\times N\times f\times\pi\times 2$$

Where \$B_{max}\$ is typically used around 300mT, \$U\$ is the applied voltage and \$f\$ is the frequncy of the applied voltage. And I should calculate for \$A_e\$, for effective core size.

From this on I've lost contact with him, so am kinda lost. While I trust him, about these equations, I am also unsure (shouldn't they depend on current?) on how to approach this problem, and solve it.

Here are some numbers with what I am working.

Low-pass filter:

current thru the coil maximum at around 7.5A
voltages across the coil will be from 12V to maximum around 27V (square wave will be applied to the filter)

Boost converter:

input voltage of maximum 15V (square wave)
input current of maximum 15A

These numbers already include some margin.

Also if I will get some large values for the core size can I connect more of them together?

How, parallel or serial? By first equation I should connect them in series (lesser turns=lesser B), but by second/third I should connect them in parallel (more turns = smaller Ae), so which is it?

EDIT:

Low-pass filters are in a H-bridge, for class D amplifier. And boost converter is what will be powering it.

EDIT2:

Frequency of the square wave applied to the low-pass filters will be around 20kHz. And frequency of the square wave produced by boost converter will be somewhere between 100kHz and 500kHz.


texts: How is digital information encoded/decoded in light or radio waves?

texts:
I know exactly how DAC and ADC works; that's not my concern.

What I am asking is how the constituent state of matter (and the "states" represented by them) in a circuit can be transferred to a set of photons (with no mass) and hold varying "states" within the analog light or Radio Waves?

I guess a simple question would be, how does electronic power get turned in to encoded data within radio waves, and how does the encoded data get decoded back in to electrical power/matter from an energy level?


texts: Understanding electron and hole mobility in doped silicon

texts:
My textbook (Jaeger's Microelectronic Circuit Design) uses what appears to be this equation to describe the hole and electron mobility in doped silicon, essentially showing that as something is lightly doped the mobility is much higher. Doping concentrations cause a rapid drop off in mobility rapidly. Here are some resources from Indiana University and Colorado University that describe the equations my textbook uses in a bit more detail than my textbook does (it only covers the subject abruptly and not much detail).

$$\mu=\mu_{min}+\frac{\mu_{max}-\mu_{min}}{1+(\frac{N_T}{N_R})^{\alpha}}$$

I'm trying to understand how these equations work in greater detail so that I can potentially use them to solve problems and think about semiconductors.

My questions: Is alpha the product of the "Base Transport Factor" and "Emitter Injection Efficiency" or was the alpha that the Colorado University used in this equation just a fitting parameter that has no relationship to that product? (the alpha they had and my book uses was less than 1 so I assumed that it was plausible that they are the same alpha)

$$\alpha = \alpha_T\gamma = \frac{I_{collector}}{I_{eliminator}}$$

I'm asking all of this because I would like to be able to solve problems such as the one below in ways that are conducive to learning. The way my book solved this problem was by using the relationship if conductivity is equal to the product of the electron charge, hole mobility and hole concentration and solving it iteratively using Matlab by trying values within a range where they know it is and using the one with the least error then using the equations I talked about above they calculate the mobility from that. They come to different equations, presumably based on the doping of the material, but neither show how one might calculate or find those equations. I don't really care so much about getting to their answer but more on how this works and how I might calculate it on my own. If this is a fitted equation you can only obtain through experimentation that's fine, I would like to know that too. Currently this process appears to be a black box to me and I would like to get into the guts of this concept.

$$\sigma =q\mu_{p}p$$


texts:
I have build simple LM317 power supply.Input is 12v (I am using computer power supply), and the output is around 4v .I was wondering, can i use this to charge my 3.7v lithium batteries?

Here is schematic of my circuit


texts: Will the following circuit cause EMI-problems?

texts:
I'm trying to get a feel for which circuits will have EMI-problems and which won't. To make things a bit more concrete, I've designed a super-simple LED-blinking circuit using the PIC16F1788 micro-controller.

I'm interested in hearing all you experienced engineers out there what your gut-feeling is - would this circuit be:

Clear-cut no risk what-so-ever of EMI-problems
Probably fine, but one would need to build it and do measurements to be sure
Seriously flawed, but might pass EMI-tests through luck
No chance of passing regulatory demands
None of the above

Here is a picture of the layout. I've drawn this circuit just for the purpose of this question.

The IC is an PIC16F1788 in SO-package. It is decoupled close to its Vss/Vcc pins with a 0.1uF 0805 ceramic cap. 5V Power is supplied from the wall wart through a connector J1. A 1206 SMD LED is connected through a 680 ohm resistor R1 to RA0 pin on the PIC. There's a 4.7uF cap right next to the connector.

All pins are configured as digital outputs and driven low, except the RA0 which is connected through R1 to the LED and toggled high/low at 10Hz. The CPU is clocked at 32MHz from the internal oscillator.

Resistor R2 pulls the reset pin high (maybe unnecessary).

The board is 2-layer FR-4, 35um copper, with the bottom of the board  a ground plane (only interrupted at one point). There's a copper fill connected to ground at the top. The grounds are not via-stitched or anything.

RC4 is connected to the antenna-like trace which goes up vertically from the upper right half of the microcontroller.

The question is, would the above circuit pass regulatory requirements? Let's assume it was to be sold in the EU (although I don't think anyone would buy it :-) ).
I hope this question makes sense. I believe this circuit would be okay with the "antenna" grounded and probably okay if it was toggled at 1MHz, but not as clear cut. Am I right?

What are things to watch out for? Which small modifications would make the circuit worse? Which would make it better?

LED: https://www1.elfa.se/data1/wwwroot/assets/datasheets/kp-3216surck_eng_tds.pdf

PIC: https://www1.elfa.se/data1/wwwroot/assets/datasheets/PIC16F1788_9_eng_tds.pdf

Power supply: https://www1.elfa.se/data1/wwwroot/assets/datasheets/gs06e_eng_tds.pdf

Edit: Here's a schematic:


texts: how switched mode power supply affect microcontroller functionality

texts:
I am using a switch mode power supply RAC06-05SC to power up the microcontroller (ATMega16L) a wifi module (RN-131G) and a 5V relay. This power supply is already regulated (as stated in the datasheet) and it is regulated further down to 3.3V for the micro and the wifi module using a linear regulator.

I am told that switched mode power supplies generate a lot of noise, and I am trying to use this with a microcontroller which will use the ADC. My questions are given below:
1. Does a switched mode power supply affect radio frequencies of 2.4GHz?
2. Will the supply abruptly switch off the power?
3. Will it effect the functionality of UART?
4. Will it effect an external oscillator?

Or any thing else I should know?

EDIT

My relay schematic


texts: How to tell if a chip's heat sink can be grounded

texts:
I'm putting together a circuit for a TI LM3549. It's an LED driver, so I assume there will be some amount of heat to manage, though the word heat doesn't appear anywhere in the datasheet, nor does the heat tab (or whatever the appropriate term for the slug on its underside is) have a corresponding pin number or name. Given this lack of information, I just left it floating. However, looking at the sample schematic on TI's evaluation board for this guy, I see a pin named that doesn't exist on the schematic - HTAB, and it's tied to ground:

I'm making the assumption that it's that slug, and that they're grounding it to link it to a larger copper area for heat dissipation. So, two questions:

Am I interpreting that correctly?
If so, how in the world can I make that conclusion from the datasheet?


texts: What is this PCB (IC?) connector called?

texts:
Can anybody tell me what this connector is called and how I could purchase one for my own prototype board?

This is a picture of a Nintendo Wii motherboard (bottom) and the bluetooth adapter (top).  I'd like to connect this bluetooth adapter to my own board for a project I'm working on so I need a connector like the one on the motherboard.

Here is another picture of both the board connector and module plug:

Thanks for any help!


texts: TMP04 Temperature Sensor with Arduino Not going HIGH

texts:
I have a TMP04 temperature sensor (3 pin package). It outputs a square wave at approximately 35Hz and the duty cycle can be converted into a temperature reading (see datasheet).

It has an operating voltage of 4.5V-7V and I have it hooked up to the 5V supply of an Arduino Uno. Using a multimeter between the power pins confirms that the voltage is ~4.96V, which should be suitable.

I was using the pulseIn()  function to read the time the pin was high, but the function would fail and always time out.

To check the output from the sensor I connected it to the Arduinos analog (ADC) input and took readings from the pin every millisecond.

There was a clear HIGH/LOW pattern, BUT there was an issue. The LOW signal was reading approximately ~15 (fine), but the HIGH signal was reading ~145. This is a very low voltage, as the ADC produces a number between 0-1024.

Hence, a reading of ~145 corresponds to a HIGH voltage of ~0.7V, which is of course not expected and wrong. The datasheet suggests that the HIGH voltage should never fall below \$V_{DD}-0.4\$.

I thought that it may have been a dud sensor, but after trying another one I get the same results.

I'm just prototyping on a breadboard, and have no decoupling capacitors as I was just testing them out.

My circuit is literally:

Sensor V+ to Arduino 5V
Sensor ground the Arduino ground
Sensor output in to Arduino (tried pin 5 and A1)

I have no other resistors or components in my circuit. Am I doing anything wrong? Have I misunderstood how I am supposed to use the sensor?

Here is a sample output from the ADC, with one reading every millisecond:

145
149
14
12
13
12
15
13
16
18
14
18
18
18
20
14
150
146
149
148
149
149
146
148
14
18
17
18
14
21
14
15
18
14
17
17
19
19
150
149


texts: ESP32 WROOM switching back from MicroPython to Arduino framework

texts:
I have recently switched my ESP32's firmware to work with python (using Thonny IDE) and I want to switch back to work with C++ and Arduino IDE, but I remmember flashing that bin file on the device.
Is there any way of making it work with Arduino IDE and C++ code?


texts:
I have a legacy LPC MCU with 2 UARTs only. One of these UARTs is reserved for different functions such as IAP and RS232. So basically, I have one UART available only.

For an experimental project I need 5 to 7 UARTs to add 5 to 7 SOC modules.

So, I plan a new hardware with any controller, but due to PCB space and controller limitations I do not expect to have many possibilities to add unlimited UARTs.

Planning some type of extender, I had the idea of using two 1:8 74xx multiplexers in order to switch between UARTs and a common VCC/GND shared by all of the participants in my SOC/MCU chain.

Can you switch safely between UARTs using analog muxes? Or are there ramps/peaks that might lead to UART periphery problems?


texts:
This might be a simple or obvious question but I wasn't able to find a distinctive answer to it.
To actually access memory, a processor writes an value to an address bus and recieves the data on the data bus. Does that mean that in Von Neumann architecture there is one data and one address bus while in Harvard architecture there are two of each (so at least 4 busses in total)?
Edit:
The US Patent US5034887A "Microprocessor with Harvard Architecture" lists symbol 18 as data bus, symbol 19 as instruction address bus and symbol 20 as data address bus (see Section 5, line 42 ongoing).
Further Fig. 12 shows the Instruction Memory (symbol 4) directly connected to the Instruction Selector (symbol 11). However, the connection from 4 to 11 is not described as "bus". Could one say that, based on this, there are at least 3 distict busses?


texts: Switching a 4-lane bus under microcontroller supervision

texts:
Looking for a simple and effective way to switch a 4-lane bus, under the control of a microcontroller (labelled as "controller"), as shown in the logical schematic below. Device-3 should be connected to Device-1 or Device-2 at any given point in time.

I am pretty sure that something like this, i.e. switching a bus, is pretty commonplace in electronics design. The bus in question is basically USB ! So we have +5V, GND, D+ and D- (5V logic). Also, Device-1 and Device-2 are "USB hostss", while Device-3 is playing the role of "USB device".

Would appreciate hints / suggestions along 2 lines / approaches -

All PTH, hobby grade, using simple to source components, i.e. no specialized ICs, apart from a common microcontroller (say ATtiny45).
Somewhat more compact (less component count), elegant and modern approach (but hopefully without SMD components).

For the 1st approach, I was thinking of using a pair of FET or BJT's (*) on the D+/D- lines for each of the devices (Device-1 and Device-2), with 1 GPIO pin controlling each pair. The +5V and GND stay always connected to both devices though, I am not sure, what it means from the USB protocol standpoint, as D+/D- are always pulled low.

If someone would like to know what I am trying to achieve, then it is a crude (but hopefully effective) switchover of a USB external hard-disk between 2 PC's, as a form of failover.

(*) I have many general-purpose BJT's in my hobby-stock, and no FET. So unless it is really an issue, I'd prefer using BJT's.


texts: Measuring RF voltage transformed by a toroid

texts:
This evening I attempted to measure the voltage off of a transformer used for detecting RF currents. This transformer was implemented as a single turn of conductor, through the center of a toroid wound with over a dozen turns. (The toroid came pre-wound, but AFAICT it's simply a bifilar winding with a center tap.)

Now, I would expect that with 1 primary winding and let's say an even 10 secondary windings, the voltage on the output should be 10 times higher than the voltage on the input, right?

But when I put about 30Vpp of signal into the primary of T1, at about 14MHz, the voltage I measured on all of the secondary ports (e.g. I was measuring at R1 and R2, referenced via the other scope probe to the same chassis ground as the input) was much, much less than the input — maybe more like 2Vpp! It seemed like I had barely any more voltage on the secondary side of T1 than I could measure on the case itself via the second probe's tip.

How could this be? I understand that there would be very little current available, but with my scope's typical mega-ohm input impedance I shouldn't expect that to be a factor, right? Likewise any voltage drop caused by the rest of the circuit, even if it the circuit is faulty, should also not be affecting the measurement, right?

I've got the turns/voltage relationship backwards despite double-checking
that something changes about the usual turns/voltage relationship as frequency increase, i.e. severely non-ideal components
that the capacitive coupling of C4 is somehow changing the game significantly
that using only one ground clip is messing up my measurements, even at only 14MHz

To be clear, my scope and probes are both supposed to be capable of measuring to 100MHz. I can see the input signal (measured at "transmitter") just fine at 30Vpp, it is only the output of the transformer T1 that is so severely reduced in voltage (rather than multiplied!).


texts: What issues are there in designing a LED lighting system to replace Halogen G4 lighting

texts:
I wish to design a lighting system using electronics and LEDs as required to replace existing G4 Halogen lamps in order to increase available light levels in the available space.

Situatiuon: Kitchen lightning mounted under the kitchen cabinets - 3x g4 (12v) halogen bulbs - like these. The bulb sockets shows "max 10W" bulbs. Looking for a way to get more light from them, but don't want replace current wiring (don't want unmount the kitchen cainets).

I found some LED replacements for g4 bulbs (like this one) - less wattage but as I saw in some forums, they gives less light too. Therefore thinking about mount 3x LED strips and power them from the current G4 bulb connectors (up to 10W) - in a hope getting more light. (The primamry goal is getting more light - saving power is secondary)

In short - my idea is:

buy some LED strips 3x 1.5m
bond them under the cabinets
unmount the g4 bulb sockets
extend the wires to LED strip
done?

The questions are:

is possible to power a 3x LED strips (each approx. 1.5-2m long) from those g4 bulb connectors?
what else i need to do / design?
What electronics do I need to build ? / Do I need to modify the halogen power supply? / Other?


texts: Quieter, faster continuous rotation servos

texts: I'm using a couple of continuous rotation servos to drive the wheels on a mobile robot.  One issue I have is that the servos produce a loud, whining sound when in use.  Do higher quality servos exist that make less noise?  It would also be great if the robot could move a bit faster - are speedier servos available?


texts: Input impedance of TTL driver in a RF switch

texts:
I have a RF switch "ZYSW-2-50DR+" which has a built-in TTL driver. So far as I understand, the driver is like a buffer which amplifies the current while keeping the voltage same(unity gain). So, in general, buffers have high input impedance and low output impedance.
Does the same thing hold for the TTL driver of the switch in question? From the datasheet, the maximum control voltage is 5 V and the maximum control current is 2mA. So, is it fair to assume that the input impedance of the TTL control port is 5/2=2.5 kilo ohms?
Actually, I want to connect this switch to a 3.3 volts source which has an output impedance of 200 ohms. So, it is important for me to know how much voltage will drop across the source impedance and how much of it will appear at the TTL in.


texts: Would a capacitor labeled 470K be 47pf or 470pf

texts: I have a cap labeled 470K. I would have thought for sure that it would be 47pf until I saw this link where it said if a capacitor has a 0 as the last digit, it is the whole thing in nano-farads. How can I figure out this without a capacitance meter. 470K 100V C is the whole label if that helps.


texts: Controlling speaker that has 4 interconnected pins

texts:
I am fairly new to and interested in electronic engineering. I want to control a speaker I found in an Xbox 360 headset with my Arduino, but I dont know how. Other small speakers I own all have 2 pins, + and -. But this speaker has 4 pins which are all interconnected. Image of the speaker:

Can someone tell me how this speaker works, or put me on the right track?


texts:
I have made a board for Arduino that has an DS1307 and an L298P. The board looks that it is working correctly. I have an RGB LED at pins 31, 33, 35 and I try to make them HIGH but the volts that Arduino gives is 1.6 Volts. I do not know if there is any problem with the circuit I think there is one. The circuit is in general free on internet for the 2 of the chips also I saw the datasheet of the chips.

Between Arduino and the board I have an ethernet board.

I used an external power with 10A at 12 volts also the USB cable and the problem is the same. Also before I make this combined board I was using two separate boards one for DS1307 and one for the motor. The RGB LED was working correctly.

The circuit for the motor does not get power from the Arduino, it has an external power supply input so only the ethernet and the DS1307 need Arduino's power in order to work.
I will give the schematics and a photo. If there is any solution please help me.

I admit at the schematic there is a mesh at the lines of the RGB but this happened in order to have straight lines at the board.


texts: Easiest way to display 10 colours in a small area

texts:
This question requires a bit of background.

I am building a resistor colour-band machine out of an egg carton. The idea is - you are making a project. You are unsure of a precise resistance value you need, so you use a pot. Once you have the setting right, you take the pot, plug it into this machine and it gives you the 5-band colour code for the resistor you need.

The trouble is how to display the colours in the egg-carton cups. I can come up with a few ideas - all flawed:

RGB LEDs - but how do you display black and brown?
LCD - but where do you get a 2X2cm LCD?
Color wheel driven by servo/stepper - but how do you make it fit?

Can you think of any ideas that will work?


texts: Which method to use for BCD division in VHDL

texts:
I'm required to build a system (prime number checker) for my advanced digital electronics class that makes use of a 16-bit BCD division module. The module has been specified according to the following VHDL specification.

I'm confused about the use of the buffer type for quotient and remainder. From the research I have done on the keyword I see that it can be used as an input/output vector where the output may be used in determining the final output. I also have a little trouble visualizing how a datapath for this system would look.

My major concern, however, is the implementation of the module I have found an example of BCD division from my searches here: BCD Division Algorithm and Example Code. However, in their implementation, they make use of a 3-bit Adder. I don't think I would be allowed to make such an addition in my implementation. I can follow the algorithm that they used and I can adapt it for my use case of a 4 digit into 4 digit divider.

Because of this, I am having trouble deciding if I should convert my dividend and divisor inputs into their binary representation and doing repeated addition to find the result or If it is possible to do the BCD addition. I'm also concerned about the time that the system might spend doing division if I use the repeated addition method if the numbers far apart, say 9999 and 2. And the algorithm provided may have multiple iterations where the divisor is being increased. I don't think spending time in the divider is a problem but does anyone have any recommendations for a method I can use or can anyone point in a direction where I can get more information on how to implement dividers?


texts:
I've read about how to determine resistor wattage but it is not clear to me which V we need to consider in the calculation.

For example, this is a schematic of some electronics I am getting familiar with.
The 75R resistor (I assume to drop voltage before the 5V regulator), is rated at 5W.
The input voltage is around 26VDC from the 18VAC transformer winding after rectification.

As such, when calculating P=V^2/R, do we use 26VDC, or just the voltage that is dropped across the resistor?

Thanks!


texts: How to design a circuit checking if 12V car battery is charging?

texts:
I have a small solar power charging module and load balancer, that takes input from a solar panel, has connectors for a car battery (12V) and output terminals.

These things are pretty common on thing like RVs, caravans, camper vans, etc.

The module however, has no digital readout displays. Attaching a couple of those to the terminals of the charger / power manager is trivial, but I was wondering how I can have an LED light up, when the car battery is charging, i.e. current is flowing in to the battery. And have no LED light up, when current is being drawn from the battery.

The Voltage / Amperage meters I use, just shows the absolute values, they don't display for instance a negative amp value to signify direction.

So, how / what would be the simplest circuit to display current direction, in to the battery (battery is being charged) and if current is drawn from the battery (battery is discharging)?

Obviously, the circuit should draw as little current as possible itself.

Edit

Couldn't I simply use a comparator, like an LM319, and use the batteries wire that connects its terminal to the power management unit as resistor? I.e. having the non-inverting input going to the battery terminal, and the inverting input to the power management box.


texts: What would happen if an LED was run in a 500F/260C environment?

texts:
I'm trying to get a better understanding of what the heat would do to the LED. I understand that LEDs and heat do not get along, but if they were put in this high heat, what would happen?

Would they still function?
Would it just be their life and/or output that would diminish?

Thanks in advance for any info you can provide.

Dave.


texts:
I want to create mobile app that will control some external simple mechanical device. I want to use bada wave s8500 for this purpose so have access to Bluetooth and WI-Fi. Now I'm looking for advice related to chip (that will translate command from phone) on my mechanical device. Of course it should be something simple, small and cheap if it is possible.

Has somebody any experience with this? I will be pleasure for any advice or idea.


texts: I2C design consideration for several slaves

texts:
In an application I have multiple I2C slave devices: display, RTC, and EEPROM. The most crititcal is the RTC, which needs to work 100%.
I read that I2C freezes from time to time. At the moment all 3 devices are on one I2C bus. Would it be better to use the RTC on a seperate I2C line? My MCU is a SAMD21 which has up to 6 I2C lines.


texts: ATmega328A UART: everything working, but not as expected

texts:
I am trying to get UART working via the ATmega328A. I want to enter a character, and get that character to be printed out. However, when my code is run this is what happens:

I enter one character, that character is printed out.
I enter a second character, and the character is printed out,But then the
first character is printed out continuously, forever.

For example, the output from the console.

<user input a 5><5 is printed><system waits for input><user enter a 3><three is printed><system prints 5 repeatedly(for ever)>

The code:

 #include <avr/io.h>
 #include <util/delay.h>
 #include <stdlib.h>
                                                      // include LCD library
  #define F_CPU 8000000UL
 #define BAUD 9600                                                       // define baud
 #define BAUDRATE ((F_CPU)/(BAUD*16UL)-1)        // set baudrate value for UBRR

                                 // set the CPU clock

 // function to initialize UART
 void uart_init (void)
 {
     UBRR0H=(BAUDRATE>>8);
     UBRR0L=BAUDRATE;                                                 //set baud rate
     UCSR0B|=(1<<TXEN0)|(1<<RXEN0);                     //enable receiver and transmitter
     UCSR0C|=(1<<UCSZ00)|(1<<UCSZ01);// 8bit data format
 }

 // function to send data - NOT REQUIRED FOR THIS PROGRAM IMPLEMENTATION
 void uart_transmit (unsigned char data)
 {
     while (!( UCSR0A & (1<<UDRE0)));                  // wait while register is free
     UDR0 = data;                                                     // load data in the register
 }

 // function to receive data
 unsigned char uart_recieve (void)
 {
     while(!(UCSR0A) & (1<<RXC0));                     // wait while data is being received
     return UDR0;                                                     // return 8-bit data
 }

 // main function: entry point of program
 int main (void)
 {
     unsigned char a;
     char buffer[10];

     uart_init();                                                    // initialize UART

     while(1)
     {

         uart_transmit( uart_recieve());

         _delay_ms(100);
     }

     return 0;
 }


texts:
I have bought a 200kg load cell and an AD620 in-amp. I only want to use 100kg as the maximum weight capacity. I want to power the load cell and the in-amp from the 5v pin of the arduino. The seller can't give me the specifications of the load cell so i'm actually having some difficulty computing for the gain.

I want an output swing of about 0 - 5V from the in-amp so i can utilize the 10-bit ADC resolution of the arduino with the default 5v reference.

Do I have to use a dual +-5V supply to have an output swing of 0-5V? What could I connect to the reference pin of the in-amp if i only have a single supply as I mentioned earlier.

I would really appreciate your help, this is for my thesis.

-----------------------------------UPDATE--------------------------------------

After I have read the datasheet and some books about amplifiers, I have tried to make a circuit so I can check if I could get the -Vs+1.1 to +Vs-1.2 output swing of the Ad620. Below is the circuit:

I have referenced the REF pin of the AD620 to half the supply by connecting it to the
output of the LM741 op amp with two 10k resistors on the non-inverting pin. After testing
some load and testing some gain resistor(as i have said earlier, the seller didn't give me the datasheet of the load cell so i dont know exactly what the exact sensitivity is), I have read an output swing of approximately half of my supply to 3.6V. That would be like 2.2V(because when i test the voltage supply from the arduino its like 4.4V) to 3.6V. Am I getting the right output from the AD620?


texts: Input output voltage problem in PIC32 starter kit & IO expansion board

texts:
I have a PIC32 Ethernet Starter kit and IO expansion board. I have a made a simple input output program in which if PINC2 is high then make PINC1 high else low. I have a circuit which gives me a output voltage of 3.3v and I am applying this voltage as input to PINC2. But there is voltage problem at PINC1.

When PINC2 is low, voltage at PINC1 = 3.276v

When PINC2 is high, voltage at PINC1 = 2.8-2.9

My question is when voltage at PINC2 is low, why voltage at PINC1 is 3.276v, it should be 0volts. and when voltage at PINC2 is high, why voltage at PINC1 is 2.8-2.9v, it should be 3.276v. I am really confused at this. Please help

CODE:

int main()
{

   TRISCbits.TRISC1=0; //output
   TRISCbits.TRISC2=1; //input
   while(1)
   {

       if(PORTCbits.RC2==1)
       {

          PORTCbits.RC1=1;
       }
       else if(PORTCbits.RC2==0)
       {

          PORTCbits.RC1=0;
       }
   }
}

Link to circuit giving 3.3v output


texts:
This question crossed my mind today.

What is the history of the MSP430?  When did it start, what did it evolve from, why was it made (i.e. what goals was it trying to achieve/what technical limitations with current uC was it trying to address), and why is it called the "MSP430"?

An internet search only revealed this power point, which doesn't say much.


texts:
SO I need to use some 1W and 3W leds for the brightnes, but my application will not allow the start heat sink.  I have come across a few articles talking about using PWM to drive LEDs  Does pulsing an LED at higher current yield greater apparent brightness?

What got me in the link above is

  as you reduce your duty cycle you can increase your current because there will be less time for heating affects to kick in. I have done this with a very very short duty cycle using a pulsed laser power supply at 2kV on a normal 1.9V diode. This was pulsing so often that they eye cannot tell. the brightness of the diode increased significantly. My professor and I built a power supply that had a short duty cycle and only overvoltaged the diode to a little over an amp of current and successfully made a normal diode look brighter then a 1W LED when it was only a cheap LED. – Kortuk Jul 28 '11 at 16:09
  Blockquote

What I'm needing to achieve is an LED that can be seen in day.  I'm putting them on a RC Airplane.


texts: rf amplifier saturation when input chirp

texts:
I am trying to generate an 11 MHz pulsed chirp signal with center frequency of 4 GHz at a power level of +10 dBm. I have an arbitrary waveform generator that can generate the correct chirp signal, but can only supply a power level of -40 dBm. I am determining this using a spectrum analyzer, and measuring the average amplitude of the 11 MHz band. The waveform on the spectrum analyzer is generally flat, with maybe +/- 0.5 dBm variation.

So I added two amplifiers in series (part number ZVA-213-S+). As far as I can tell this should give me a minimum of 40 dB gain, or a typical of 50 dB gain. Unfortunately there is some kind of saturation happening, and I am maxing out at around -16 dBm. I can lower the power level of the arbitrary waveform generator until I see the power level dropping, but once I start increasing the power level, I can't get past -16 dBm even though the waveform generator claims its output power is still got room to increase. The spec sheet of the amp claims that it can provide an output of +33dBm, typically.

I repeated this test using  a single tone pulse at the same frequency. With this I could see the expected gain of 50 dB.

I verified everything was fine in terms of providing power to the amplifier. It's the recommended 12 VDC, and the power supply can provide up to 5 amps.

Is there some fundamental difference when applying a chirp signal to an amplifier versus a single tone that would cause this?


texts: Wearing 1 LED isn't much of a problem. It only requires a few volts and ~25mA of current. But what about 100+ LEDs? It depends on the number of LEDs in series or parallel (or both), but would it be enough to do serious harm to someone?


texts: I need to connect a SATA device to a development board which does not have a dedicated SATA connector but exposes SATA over a common 2x30 female header instead. My question is what cabling do I need for short length (say 15 cm)? Do I need to bother with cable shielding or is it possible to run SATA reliably over unshielded cable? The setup will operate in a passenger vehicle. The board I use is a phyBOARD-Mira i.MX6.


texts: How can I fix my multimeter which consistently shows 0 for AC voltage?

texts: I have a MAXIMUM multimeter ( https://www.canadiantire.ca/en/pdp/maximum-digital-multimeter-with-true-rms-0521898p.html ) that I've been using for about a year, mainly for automotive and hobby applications. However, yesterday I needed to measure AC voltage and consistently got a reading of 0. I tried plugging it right into a household plug and it still reads 0, though it beeps and the NCV light come son to warn me there's an electric current. It works on every other setting including DC voltage, and interestingly even works on the frequency setting. I've tested both fuses with another multimeter and they both have continuity. Is there anything I can try to fix it? I know it's not a Fluke or anything, but it's still pretty expensive and it's a shame to have such an important setting not work.


texts: WS2812B LED strip interference with PC monitor

texts:
As post title says I think I have an interference issue between a WS2812B LED strip (98 LEDs) and my PC monitor Viewsonic VX2458. The LEDs are connected to the back of monitor in a rectangular shape and controlled from PC software by an Arduino board as an ambilight. I have a 6A 5V power supply powering the LED strip.
The issue I am seeing is:

When the monitor goes to sleep instead of staying asleep it will randomly (from few seconds to few minutes power up) - show up no signal massage and goes back to sleep.
When I switch off the PC the same thing happens even when LEDs are off at this stage.

The cable from the power supply and the USB cable going to the Arduino has ferrite clips. I also put additional ones on each cable close to the first LED.
Looking for any other ideas and possible solutions.


texts: Will utilizing a TIP120 transistor to control the power from 2 9volt batteries in series powering a 12volt fan generate heat?

texts:
I want to utilize the below circuit to power a 12volt fan with the components listed. I'm concerned though because when I tried to do this with a resistor, the resistor got -very- hot. I understand why but if I utilize the transistor will it cause it to heat up? Does utilizing the transistor result in a more efficient use of power with less heat loss?

Thank you

Circuit diagram and tutorial from here:
http://www.instructables.com/id/Use-Arduino-with-TIP120-transistor-to-control-moto/


texts: Opamp demonstrates slew rate much lower than specified in datasheet

texts:
TL,DR: Use a comparator, not an opamp. See Frosty's answer below.

I'm trying to make a pulse waveform generator with variable duty cycle. The 555 timer is used to generate a sawtooth waveform, which is then compared to a constant voltage from a voltage divider. The schematic works in principle, but for some reason the output of the opamp has a very low slew rate.

This is the schematic:

Vcc is 5 volts. R1, R2 and C1 are such that the width of one tooth of the sawtooth waveform is roughly 200 microseconds (I'm seeing that with the scope). However it takes roughly 10 microseconds for the output of the opamp to go from 0 volts to 4 volts.

The opamp in question is TL072, which, according to its datasheet has a typical slew rate of 13V/us. There's also a graph that is showing "Normalized slew rate", which is roughly 1V/us at +/-15V power supply.

Am I misunderstanding what slew rate really is? Shouldn't this amplifier go from 0 to 4 volts in about 0.3 microseconds?

UPDATE: The circuit behaves as described with no load.


texts:
I would like to determine the following transfer functions:
$$T_1=\frac{y^\wedge}{d^\wedge}$$
$$T_2=\frac{y^\wedge}{r^\wedge}$$
$$T_3=\frac{e^\wedge}{d^\wedge}$$
$$T_4=\frac{e^\wedge}{r^\wedge}$$
In the following system:
$$\begin{bmatrix}d^\wedge\\r^\wedge\end{bmatrix}
=\begin{bmatrix}1&-C\\ P&1\\\end{bmatrix}
\begin{bmatrix}u^\wedge\\e^\wedge\end{bmatrix}
$$whence
$$\begin{bmatrix}u^\wedge\\e^\wedge\end{bmatrix}
=\begin{bmatrix}1&-C\\ P&1\\\end{bmatrix}^{-1}
\begin{bmatrix}d^\wedge\\r^\wedge\end{bmatrix}=\begin{bmatrix}(1+CP)^{-1}&C(1+PC)^{-1}\\ -P(1+CP)^{-1}&(1+PC)^{-1}\\\end{bmatrix}
\begin{bmatrix}d^\wedge\\r^\wedge\end{bmatrix}
$$

I therefore wrote:
$$\frac{u^\wedge}{d^\wedge}=(1+CP)^{-1}$$
$$\frac{u^\wedge}{r^\wedge}=C(1+CP)^{-1}$$
$$\frac{e^\wedge}{d^\wedge}=-P(1+CP)^{-1}$$
$$\frac{e^\wedge}{r^\wedge}=(1+PC)^{-1}$$

Now, may I use the relation $$y^\wedge=u^\wedge P$$ hence multiply both $$\frac{u^\wedge}{d^\wedge}=(1+CP)^{-1} and \frac{u^\wedge}{r^\wedge}=C(1+CP)^{-1}$$ by $$P?$$


texts: listed ac motor horsepower doesn't match voltage and amperage

texts: In my search for a bandsaw, I've come across a model that has an AC motor whose plate displays 3/4 Horsepower, but also 115/230 volts, 11.2/5.6 amps. You can see that the math suggests (115 x 11.2 = 1288, 1288 / 746 = 1.7) a horsepower rating which is double what is stated. For the money, I'd much rather assume the higher number. How can the two very different figures be reconciled?


texts: 100-240VAC 0.25A to 24VDC 0.4A Swiching Power Supply AC Ground

texts:
I'm working on a low-voltage power supply and relay design. The switching power supply, a Mean Well PM-10-24, works on 100-240VAC, 0.25-0.15A 50/60 Hz and outputs 24VDC 0.42A. The AC inputs are AC/L and AC/N. There is no input ground.

My question is: why doesn't this type of power supply have an AC ground terminal? I noticed that small switching power supplies don't seem to have earth ground points. I don't feel comfortable connecting earth ground to AC/N. Is there a suggested grounding circuit design that is standard for small switching power supplies like the Mean Well PM-10-24?


texts:
I'm really confused about the working of a Bipolar Junction Transistor (N-P-N).
Just consider the below figure:

1) Clearly the Base-Emitter junction is forward biased and Base-Collector junction is reverse biased, so when the current Ib flows to the base
it meets the current Ic, but they are in opposite directions, so won't they cancel each other? If that happens, then, when we increase Ib, Ic should decrease.But in reality the opposite is observed, i.e whenever Ib is increased Ic also increases proportionately.Why does that happen?

2) I also have a doubt about the current flow, will the current Ib flow as depicted in the below given diagram?


texts: Series BJT transistors with bases connected through a resistor

texts:
For an assignment I was given a problem which consists of two BJT transistors, a PNP and an NPN, in series with their bases tied together.

simulate this circuit – Schematic created using CircuitLab

The question is to find the voltage at each node. Additionally we are given the fact that \$\beta\$ of Q1 is 70 and \$\beta\$ of Q2 is 120. Q1 has an early voltage of 80, and Q2 has an early voltage of 100. Both transistors have a \$V_{eb}\$ or \$V_{be}\$ drop of 0.7 V, respectively. I tried solving using the simple models of PNP and NPN transistors but I keep getting current-controlled current sources in series. I don't understand what the current through each collector would be given that the bases share the same current. Is there a reasonable way to solve this that I am missing?


texts: how do I dispose of fluid from a lead acid battery?

texts: I am reconditioning a 12v lead acid battery, and a process I am trying requires me to remove aprox 2.5 to 3 oz of battery fluid from each cell. Before I do this, I'd like to know how to dispose of the removed fluid? Can I just neutralize it with baking soda?


texts: Will this work? Transistor to keep the uC power supply on once a trigger happens

texts:
I am trying to have a switch (momentary) on a remote, that will send power to the LDO.
But as the switch is momentary, the power will be disconnected.
Can I have a transistor or some Mosfet to keep the power on, via the microcontroller pin,
once the microcontroller is powered on.
This way the microcontroller can cut the power once done, and whenever the button is pressed,
the microcontroller can keep the power on, until work done, or another button is pressed.
Is there any example circuit for the same, or any better way. On/Off switch is not possible, due to design constraints.


texts:
I wonder how wrong is it to assume that in general case for a non-directional antenna the wifi signal level distirubiton can be described with the function
\$y(x) = b - \frac{k}{(x+a)^2}\$, where x is the distance module from the point of measuring the signal lvl to the position of the antenna (wifi-router or other signal source).
The parameters \$ b, k \$ and \$a\$ (all positive) can be determined using 3 different points (one of them in the closest proximity to the source antenna).

I need all this for my graduate project in which I need to create a model which would provide the wifi signal level in desired points in a room after taking some measurements.


texts: Are 32-bit ALUs really just 32 1-bit ALUs in parallell?

texts:
I'm reading the high esteemed text Computer Organization where this picture is found that is supposed to represent a 32-bit ALU:

Is this technology really how it's done, just a lot of 1-bit ALUs, so a 64 bit ALu would just be 64 1-bit ALUs in parallell? Some how I have doubt that this is how a CPU is built in practice, can you confirm or tell me more?


texts: Difference between differential op amp and comparator

texts:
What is the difference between a differential op amp and a comparator? I know a comparator can only give me two values (the supply values).

The differential op amp amplifies the difference between the inputs...but should a comparator not do the same then? What is the specific difference?


texts: Where would be the best spot to put a logarithmic volume control on this TPA3122 audio amp?

texts:
I'd like to add a volume control to the following circuit (a 2x15W Class-D Stereo Power Amp Kit). The schematic below is an image clipped from a PDF I found describing it.

This'll be being driven almost exclusively from my PC soundcard in case that changes anything. (I'd rather not exclusively use software volume control; I prefer the preciseness of an analog potentiometer :P)

Using a rheostat circuit on the audio input vaguely comes to mind, and that might turn out to be all I need, but I thought I'd ask anyway since I'm not certain (I know precisely zero about electronics).

I'm not familiar with the TDA3122 but I was thinking maybe fiddling with the GAINA0/GAINA1 lines might produce the effect I'm looking for...? What might I alter here?


texts: hi every bod y i would like to know what kind of adders and multipliers architectures are used in IEEE.numeric_std.all


texts: What do apparent power, real power, instantaneous power and reactive power all mean in AC circuits?

texts:
We've just started AC circuit analysis in class, and the terms that I mentioned above popped up all at once. I'm new to the idea of phasors(I usually visualize them as arrows making a certain angle with another reference arrow), and I can visualize V and I, but how does power be represented as a phasor?

The phasor representation is $$S=P+jQ$$ and what actually are these terms? I know P is the average part. What exactly does Q represent, the RMS reactive power? And what is the relation between these terms and instantaneous power? Is S here instantaneous power?

P.S: Sorry about so many trivial/stupid questions. The things kinda made sense individually but I can't seem to connect the dots.


texts:
I have a PCB that I use to make some measurements on a proprietary silicon chip. We are including a number of test structures on the PCB to allow for some automated tests, for example relays that open/close some connections, analog multiplexers that allow the sensing of certain pins of the chip, and so on.

All the test structures are controlled via 'dumb' I2C IO expanders, you control them via I2C and can set the direction of each pin, input or output, and you can set the logic state, or read it.

On the board we have a microcontroller that serves as interface between the PC (USB) and the board itself (I2C).

At POR all the expanders pin are configured as inputs, so each time that you want to use the board you need to connect it to a PC, run a small piece of code to preset it correctly, and then use it.

This is of course acceptable if you need to run automated tests, but is not so convenient if you just want to power it and use it quickly, or if you need to send it to a customer that wants to evaluate the silicon, because distributing all the software is not an option at this time.

There are various approaches to solve the issue.

Jumpers
We have a number of them, but it becomes cumbersome quickly, we are talking of more than 100 IOs. Moreover, if you want to be able to bypass a relay entirely, i.e. forced open and forced closed, you need two jumpers.

pull up/down
This is a bit more attractive, but it kinda defeats the purpose: I want a software reconfigurable hardware, I don't want to rework tens of boards if I find a bug.

The ideal solution
I am dreaming of a very simple chip, like an I2C EEPROM or something like that, where you write a sort of boot sequence:

0xAE  0xAA
0xAE  0xBC
0x18  0x00

And so on. The data above represents couples of address, data. This fantastic chip should have a gpio input to which I can connect a button: when I press the button, the EEPROM should act as an I2C master and send the data on the I2C bus, so as an example the bytes above mean "Send 10101010 to 0xAE, then send 10111100 to 0xAE and finally send 00000000 to 0x18".

My question is:

Is there a better way to initialize an I2C IO expander?
Does the chip I envisioned exist, or should I just suck it up and use a microcontroller?


texts: I have installed LED tubes in my kitchen ceiling light. They replaced the old fluorescent tubes. I removed the ballast and wired the fixtures according to instructions which essentially connected the tubes to the 110v circuit. I made the same conversion at other places with no problems. In this case, the LED lights will not illuminate when the other lights in the kitchen are on. When the other lights are switched off, the ceiling light comes on. It stays on when the other lights are then turned back on. The other lights in the kitchen are also LED lights that are smaller circular lights mounted under the cabinetry and surround the ceiling light on three sides. The ceiling light and the cabinet counter lights are fed from the same circuit, but are switched separately. Additionally, the ceiling LED light will not illuminate while the microwave is operating. Once the microwave stops operating the ceiling LED light comes on. When the microwave is started while the ceiling light is on, the light then remains on. It is just that it will not start with the counter lights on or the microwave operating. The microwave is on a completely separate circuit. The manufacturer of the LED tubes does not seem to know what is happening. I am familiar with household wiring but not the circuitry components of a LED light. Would the EM radiation from surrounding fixtures be enough to affect the LED light tubes and prevent them from starting?


texts:
We are trying to run an AC generator on an RV for a customer. On an RV as you drive the engine RPM goes up and down. As I understand it, that would change the outlut AC frequency.
Is there an electronic device that I could use to keep the output frequency  at a steady 60 Hz?


texts: Both the KCL and KVL equations are required to completely model a resistor network. However, the two main methods to analyze these circuits Nodal analysis and Mesh analysis only use KCL and KVL respectfully. In other words,these methods don't use the "complete model of the circuit" (i.e. Nodal analysis ignores the KVL part of the circuit model). Yet somehow they're able to completely analyze the entire circuit - how? How is something that doesn't take the entire model into account able to completely analyze the circuit?