texts: Text LCD doesn't function normally on mixed-signal PCB?

texts:
I have power supply, analog part and microcontroller part on one 2-layer PCB board, very simple. The LCD is on the microcontroller part. It works normally when I have it on a separate board with only the microcontroller, but when I put it in this board, the LCD only displays black dots, not text.

I have tried a few times but it still gives me the same result. I was wondering whether my PCB has any problems? Is it a grounding or decoupling issue? Or something else? Please take a look at my PCB and give me some advice.

[

For more information, the power supply comes from a 7805 (on the Left Side of the Board). It drives a Cypress 27443 PSoC mcu, 1 INA126 Instrumentation Amplifier and 2 OPA4137 Op Amps. However I didn't put in the OPA when testing the LCD. The bottom part of the board is for the Amplifiers.


texts: Lowest energy wireless protocol for specific wireless sensor node

texts:
There are so many options for low-power wireless communication these days. BLE is everywhere, and many other manufacturers try to push their protocols as well. LoRa, Dust, Zigbee, Thread, Sigfox, etc., the list is long. What I think is lacking is a good way to compare the total energy consumption. Data rate and transmit power are easy, but there are so many other variables that make it difficult to compare.

What is interesting is the lowest possible energy consumption for a transmission period, and thereby the longest possible lifespan, but obviously also for the sensor node to function in the environment it is designed for.

This question would be much too broad without some constraints, so these are listed below.

Q: Which is the most low energy wireless protocol?

Constraints:

Industrial enviroment (WiFi present, but not crowded 2.4 GHz like
residential areas)
Data packages of 10 kB (kilobytes)
Range up to 150 m inside steel structure with some steel obstacles
Transmission period 1/week
Network of potentially 1000 nodes
Highly predictable lifespan if supplied from primary battery
It is allowed for a power manager to disable the voltage supply to the wireless subsystem, though some protocols are designed to be always powered and have a low power keep-alive communication going (Dust comes to mind)


texts: Parallel ATX Power Supplies - for more power and redundancy

texts:
I wanted to ask the question about two parallel power supplies.  I was asked by a friend if these would be a good idea Add2PSU
At first thought it looks very simple and good idea to connect 2 ATX PSUs in parallel, and let them share the load for more power and redundancy (in case of failure in one of them).
The problem is, ATX power supplies can vary quite a bit (more than a few mV)  One can be 11.9V one can be 12.6V. That can cause voltage drawn from one power supply to another, which can be even dangerous.
Maybe if there was an inline diode I guess on each rail. The question is about the diode voltage dropdown, and the need to deal with the heat (450W could come over the diode).
I don't really know much about the guts of how ATX power supplies are regulated/output, but since these put out high current I wanted to be safe and ask where people would know
Thanks for any input


texts: how to connect Capacitor in audio circuit

texts:
I am making an audio amplifier circuit using TDA7297 which I got from an old tv circuit. At the input I have connected two capacitor in series with pin 4 and 12. Also two capacitors are connected to pin 4 and 12 to the ground as I figured out from the tv circuit. But when I connect an input there is only a buzzing sound. I want to know if the capacitors connected between input pins and ground are causing the problem as there are no such capacitors in the circuit shown in datasheet of IC.
The capacitor C3 and C4 has value of 2.2nF (222)


texts: 18650 in series while charging using TP4056 and connecting two buck regulators LM2596 in parallel, is it safe?

texts:
I'm building a robot which contains a battery system. The 3x18650 batteries are connected in series and are charged using TP4056 boards. The voltage is then fed into the circuit shown below. The voltage dividers and power resistors assist in obtaining the voltage and current of the system.

My questions are:

Is connecting the batteries in series while charging a bad idea?
The buck regulators have a maximum current output of 3A, that is why im thinking of connecting two of these boards in parallel to share the load, is it safe to do this?
Any thoughts of improving the system.
What is the simplest way to get the Arduino to know if the batteries are being charged or not?


texts: Microcontroller registers (atmega16) Can we store the value of a port to a variable directly using portx register without the pinx register?

texts:
Can we store the value of a port to a variable...I mean is
c=portd;  possible?
If so..why do we have a pinx register to read values?
What is the difference between the two?


texts:
I want to add additional network interfaces to my BeagleBone Black. I would like to use an Ethernet module I found, EM2803_SCH, and want to figure out how to configure the pins on my BeagleBone's expansion ports such that the Linux distribution running on my BeagleBone will be able to recognize it. I've noticed that the schematic's PIN OUT labels don't match any of the pin names on my BeagleBone's expansion ports, which makes me thing I've missed something terribly important.

I'm not looking for a breakdown of how to build this thing. I'd appreciate learning resources more than anything. Is there some information (that is, reading sources, concepts to be familiar with) for what needs to happen to connect my Ethernet module to my BeagleBone?


texts: Collector voltage for this transistor circuit

texts:
For the circuit below, $$β = 80 \quad and \quad  V_{BE} = 0.7\;V$$

I applied KVL to the closed loop on the left -base-emittor loop- and the bigger closed loop on the right -collector-emittor loop- (just the bigger rectangle on the right). I thought that V0 would be equal to the voltage between GND and the wire that the upper 10k is connected to, which is V subscript CE.

So from the first loop I mentioned,
$$-1+120\times10^3I_B+V_{BE}=0$$
$$-1+120\times10^3I_B+0.7=0$$
$$120\times10^3I_B=0.3$$

Thus,
$$I_B=2.5\times10^{-6}\,A=2.5\,μA$$

From the equality
$$I_C=βI_B$$
$$I_C=80\times2.5\times10^{-6}\,A=0.2\,mA$$

Applying KVL to the second loop I mentioned above,
$$-V_0-10\times10^3I_C+20=0$$
$$-V_0-10\times10^3\times0.2\times10^{-3}+20=0$$
$$V_0=-2\,V+20\,V=18\,V$$

Thus,
$$I_0=\frac{V_0}{10\,kΩ}$$
$$I_0=\frac{18\,V}{10\,kΩ} =\,1.8\,mA$$

But the book says
$$V_0=12\,V \;and\; I_0=600\,μA$$

I found some people saying the book is wrong, but I wonder about the answer, and

How would you solve this?
Is the sentence in bold (above) true?


texts:
I connected three LEDs to 3 GPIO pins in the ESP32. They used to blink as expect previously. But now, they don't. The code is as follows.
//Testing ESP32's LEDs

const int redPin = 25;
const int greenPin = 26;
const int bluePin = 27;

void setup() {
  pinMode (redPin, OUTPUT);
  pinMode (greenPin, OUTPUT);
  pinMode (bluePin, OUTPUT);
}
void loop() {
  digitalWrite (redPin, HIGH);  // turn on the LED
  delay(1000);
  digitalWrite (redPin, LOW); // turn off the LED
  delay(1000);

  digitalWrite (greenPin, HIGH);  // turn on the LED
  delay(1000);
  digitalWrite (greenPin, LOW); // turn off the LED
  delay(1000);

  digitalWrite (bluePin, HIGH);  // turn on the LED
  delay(1000);
  digitalWrite (bluePin, LOW); // turn off the LED
  delay(1000);
}

I checked whether there is a voltage going through the GPIO pins. Turns out it just spike up for a short while and goes back to zero. Then goes to a negative voltage and goes back to zero.

Any idea what might be the cause of this?


texts: How to find a male and a female D connectors 15 pins, in altium designer Summer 09?

texts:
I need to design a adaptor with a male and two female connectors, pin to pin connected. The connector is a D connector 15 pins.
I found a D connector 15, that was what I was looking for, however, I don't know how to encounter its match. They have different names ? I know the pin numbering are mirrored, but I do not want to do it manually and take the risk of make a mistake.
Does someone know something about how to find it ? I'm using Altium designer Summer 09.


texts: Frequency response of BJT frequencies with CE bypassed

texts:
In a lot of reference I see divergence like Zce = RE || (beta re + Rb || Rs) / (beta + 1) etc.
$$Z_{ce} = R_E || \left(\frac{\beta.r_e + R_b || R_s}{\beta + 1}\right)$$
See link 1, link 2, link 3, link 4
but from a trivial example I get
Zce = RE || (beta re + Rb || Rs) / (beta)
$$Z_{ce} = R_E || \left(\frac{\beta .r_e + R_b || R_s}{\beta}\right)$$

Note : with that, i get the same result than here with the result of  Electronic Devices and Circuit Theory, by Boylestad and Nashelsky.
Note : I know with beta >= 100 it is the same but i like to have a rigourous demonstration.
Do you think it is a good reasoning here ?


texts: Crystals, Oscillators, and Resonators. What the difference?

texts:
I am trying to figure out the difference between crystals, oscillators, and resonators.  I'm starting to grasp it but I still have some questions.

From my understanding, an oscillator is built from a crystal and two capacitors.  What is a resonator then?  Is it a difference in terminology?

If an oscillator and a resonator are similar, why do these two items:

http://www.digikey.com/product-detail/en/HWZT-16.00MD/535-9379-ND/675574

http://www.digikey.com/product-detail/en/FCR16.0M2G/445-1646-ND/653108

have two pins out and no ground.  Whereas this one

http://www.digikey.com/product-detail/en/ZTT-16.00MX/X908-ND/170095

has three pins one of which is a ground?

Will any of these three devices work as an external clock for a microcontroller?

PS:  Bonus points for an explanation of how the capacitors help the crystal work properly. :)


texts: How to reduce full sine wave LUT to a singe sine quadrant?


texts: Can a Computer Motherboard Speaker/Buzzer output voltage switch a relay?

texts:
Most 12v relays I've come across require 4v to switch on. I don't have a voltmeter handy to test my computer motherboards voltage output, and if it did give out +4v and held a long enough duration would it even be possible?

Using C# or any programming language I can send a frequency and duration signal through the motherboard speaker pins so I'd like to use this as a cheap mod to control an actuator.

:)


texts:
The output power is 100hp and slip is 0.02 and efficiency of 90%,4 pole induction motor

Want to find the shaft torque(output torque).

So I guess to find the torque we use the equation

P(out) = T(out)/w , but i'm not sure w is same with input(?) w.

here is my tried solution

Td = p(out)/w
S= ns(1-s) , 0.02 /(1-0.02) = ns = 0.0204
And find the n
S= ns-n/ns , n= 0.01992
Pg = Tw,
T(out)= 74.6kw/[(2pi/60)n]= 35761

can i use the same w for output power torque? and why?
Also, please check the solution.


texts:
The first approach :Assuming 0v at both bases, when the base input of Q1 rises, its collector current rises and its collector voltage goes down. When the base input voltage of Q2 rises by the same amount, the same happens and its collector voltage also goes down,so the voltage difference between the two collector voltages will be zero.

The second approach : the same thing happens as the first approach but each emitter of both transistors acts like an input to the other and each transistor acts like a common base amplifier and the collector voltage will be in phase with emitter of the same transistor, and out of phase with the amplified signal from its base so they will cancel and the voltage of any collector to ground will be 0v.

I think i confused you a little but here's a photo from "electronic devices" by floyd to make the second approach clear.

I know i got something wrong -as usual- but i want to know where.


texts: I would control a relay (JQX-15F) with 3,3V but I don't know any component to do it. Do you know some components to do it? For example analog switch, optocoupler o other?


texts: Is this sufficient filtering for an mcu?

texts:
I'm a software engineering student and an electronics hobbyist, and I am currently designing a circuit using a 80Mhz pic32. I wondering if the noise filtering that I have is acceptable and if it could be improved.

The data sheet says that you can optionally have an inductor(ferrite bead?) between the Vdd and AVdd, would this be a good idea? I will be using the adc for measuring temperatures.


texts:
Can anyone please identify this 6 pin SMD integrated circuit or what it does? I could not find it by the code written on it.
It is from a solar charger controller and I need to replace it.


texts: Why does the Datasheet for the ATMEGA88 have two pins for PORT D bit 5 (with different functions, too)?

texts: The ATMEGA88 Datasheet has two pins for PD5 on page 3 for the TQFP layout. Those pins being Pin 9 and Pin 12. Normally, I wouldn't blink twice, but It seems that both pins have different functions. Is this a typo, or intentional?


texts: Why is my power MOSFET heating up when on?

texts:
I'm switching a 12V 500mA resistive load (LED strip) with a IRF540 MOSFET and it's getting very hot when it's on and conducting.

This confuses me as MOSFETs are supposed to have very low on-resistance and be great for power-switching applications. I'm driving the gate at 12V, and the data sheet says that the IRF540's RDS is 0.077Ω at a VGS of 10V, so at 500mA current it should be dissipating a tiny amount of energy:

  P = I2 ⋅ R

  P (W) = (0.5)2 (A) ⋅ 0.077 (Ω)

  P (W) = 0.01925

... but what I see must be dramatically greater than that, because the TO-220 package gets too hot to touch comfortably after a minute or so. CircuitLab says ≈ 1.8W which seems more reasonable from the heating observed.

What's my beginner mistake?

Edit: If you're reading this and interested in driving LED strips, see also Design considerations for LED strip PWM dimming .


texts: Error when using vPortFree(ptr) CMSIS-RTOS on STM32F4

texts:
I will need to handle dynamic memory using malloc and free. Looking on FreeRTOS documentation, I found pvPortMalloc(size) and vPortFree(ptr) , pvPortMalloc(size) works fine. When try to release memory using vPortFree(ptr) inside a Thread, the code hangs on that call.

I'm using heap_4 for CMSIS-RTOS on TrueStudio.


texts: Detect headlights left on when engine not running

texts:
I have an old and simple car (Renault Express gasoline engine 1990). I bought it because it has almost no electronics and is simple to repair. I discovered one of the drawbacks with the simple technology which is that it will not warn me if I have left the headlights on when parking the car. I sometimes drive with headlights on as I live in a forested area where the light is often poor. I intend to get LED running lights but until then I need to detect:

Are the headlights switched on
The engine is not running.
If 1 and 2 are true then I want to sound a warning.
I would like to do this using passive components such as diodes and relays and possibly a Hall effect sensor but avoid using microprocessor. The car has 12volt electrics with negative earth.
I had thought to power the sensor circuit from the courtesy light circuit which switches on interior light when the door is opened.

Question 1. Can I wrap a few turns of wire round the headlight supply line and use a Hall effect sensor? What kind of output will the sensor produce? Can I connect the output to a relay to sound the buzzer?
All suggestions gratefully received. Today I had to call the breakdown service for the fourth time to start the car. I know I can do better!
I have the usual boxes of various components just waiting to be put to good use.
Best wishes to any reader.


texts: What voltage do electrical fly killers use?

texts:
I am interested in the voltage used in electrical fly killers - does anyone know (no speculation please) the voltages generally employed? To be clear, I am talking about mains powered, wall-mounted devices.

I would also be interested in the general topologies used - I am guessing some sort of self-resonant flyback with an unrectified output. Anyone know for sure? I haven't pulled one apart yet...


texts: Is therea mcu/cpu with an isolated stack (via hardware or compiler)?

texts: There's the harvard architecture, which isolated the data and code buses. Is there an architecture which also isolated the stack bus in hardware ? or at least some compiler that implements a dual stack - one for return addresses and registers and one for local variables ?


texts: Filtering brushed dc motor PWM noise from current sensor

texts:
I'm trying to measure the current through some brushed DC motors ( midwest motion S22-346F-24V GP52-079 ) using a small custom USB current sensor based around the INA226 and FT-232H.

The device works reliably during testing with a bench supply and it works reading motor current while low side sensing, but when the motors switch direction the device becomes a high-side sensor and the resulting 24 V PWM into IN+ and IN- creates 20 V noise spikes on the USB5V line, so the USB devices reset/shutdown.

I've measured the PWM signal amplitude (24 V), frequency (~15 kHz), rise (94 ns) and fall (150 ns) times and I don't understand why noise spikes are being coupled into the DC bus. From what I understand this kind of coupling should occur if:

the traces/wires are carrying high current
trace length is long enough to act as an antenna

Case #1 shouldn't happen because the INA226 is a high impedance voltage sensor, case #2 shouldn't happen because the sense resistor wire is only ~15cm, and the trace length on the pcb is only another few cm, which is much to short for the 15 kHz PWM, or even MHz range noise from the 94-150 ns rise and fall times.

I'm looking for advice on:

Any incorrect assumptions or mistakes in analysis
How the noise is coupling into the DC power bus.
Filters I can use to reduce the voltage spikes ( I've been considering a differential ferrite choke from Rs, or implementing something like this TI app note )

Attached are the schematics and block diagrams. I also created an imgur album with some 'scope readings


texts:
I tried connecting the output of my 12V 5A power supply to a Peltier module (TEC1-12710) which has a maximum voltage of 12V and max current of 10 amperes. Following this, the power supply LED started flashing along with some clicking noise.
I connected the output to my multimeter and the voltage seemed to be increasing to 3V then back down to 0V and so on.
I think what is happening after some research online is that the power supply's overcurrent protection feature is triggering, maybe because the load is drawing too much current or something along those lines.
I connected the power supply to another Peltier module (TEC1-12706) I had which has a lower maximum current of ~6 amperes and it worked just fine.
So from all the testing I did I believe my theory might be correct that the overcurrent protection is triggering, but I'm not so sure how to move forward. Do I have to buy a completely brand new power supply, or is there a way of powering the TEC1-12710 with my current one?


texts:
I am developing an embedded system that contains a 12 V lead-acid battery. The system is developed for 12 V vehicle applications, also using a 12 V lead-acid battery.
I am not so sure how to connect both batteries.
The capacity of the vehicle's battery is much more than the embedded system, so, we desire that the vehicle's battery could charge the embedded battery. In addition, when the vehicle's battery is turned off, the embedded battery could not supply all vehicle systems.
The illustration below is a secure connection for the system?


texts: DC Motor as a Generator Voltage and Current

texts:
Is there any way to calculate the expected voltage and current, assuming I am turning it at the specified RPM value, when using a DC motor as a generator without physically testing it?

In my case I wanted to use a DC motor with the following parameters:

DC 6V
6300 RPM
Torque: 0.1Kg.cm


texts: Can a 12 volt voltage regulator be used to charge a 12 volt battery system using solar panels

texts:
I have a 3 X 18650 battery set with bms. I would like this to be charged using a 12 volt solar panel which outputs anywhere from 15 to 20 volts. the BMS has a max voltage rating of 12.8 volts.
I was wondering if it would be possible to use a voltage regulator like 7812 to regulate the output of the solar panel to 12 volts so that it could charge the batteries?
I do not want to use a solar charge controller if it can be avoided.


texts:
I have a 3 cell Li-Ion battery connected in series and want to charge them with a single battery charger IC. What I found is BQ24105, a Stand-Alone Battery Charger with following schematic for charging 2 cell battery.

Problem

Does this battery charger IC, handle cell balancing?
Is cell balancing required, I ask this because this IC claim to charge multicell battery, but dont seems to handle cell balancing


texts:
In Razavi's Design of Analog CMOS Integrated Circuits (page 126 in second edition), he presents two variations of the Gilbert cell, one were the control voltage is applied to tail current sources (left) and one where the control voltage is applied to cascode devices (right):

For the version on the left, he says that if \$V_{cont1}-V_{cont2}\$ goes very high, then the current is routed through the diff pair of transistors \$M_1, M_2\$ and the gain is negative. If the differential control voltage goes low, then the tail current is routed through the other diff pair and the gain is positive. This makes sense since it's just two side by side diff pairs whose gains make sense given the definition of the output voltage polarity.
For the gilbert cell on the right, there are the following two situations depending on if the control voltage goes high (left) or low (right):

Here, Razavi says that the left version has positive gain and the right version has negative gain. The output voltage polarity isn't explicitly shown, but I would assume that it should be the same as before since nothing special was said, so left branch is the positive terminal, right branch is the negative terminal. If that were the case, then shouldn't the left version actually have negative gain and right version have positive gain?


texts: Current Leakage calculations regarding shock hazard. A complete picture?

texts:
There is a quantity called current leakage which has always confused me. By reading various definitions, it seems to be the current flowing through the ground circuit of a device (whether this be an actual safety circuit for class I appliances, or the human body in the case of class II appliances). Some sources say it's the current flowing through the insulation, and when a human contacts a conductive part; the current leakage flows through the human.

My question is; how exactly does this quantity come into play when compared to the typical way of thinking about electric shocks (the applied voltage divided by resistance, then refer to a table of safe current limits)

I found this post interesting What is the right way to understand the behaviour of shocking voltage?

Considering all this information, something doesn't feel quite right. The issues I have are the following :
1) Is current leakage simply the maximum current that would pass through the body? (If that's the case, how would you work out the actual current passed through the body?)

2) How is current leakage related to the 'applied voltage' from above? If currentleakage x insulation resistance = 'applied voltage', this would lead to ridiculous results such as dying if you touch plastic.

3) can the body be treated simply as a parallel resistor? I've followed through with some of these calculations and the numbers don't make sense. And current leakage seemed to be made redundant/irrelevant even though it's clearly not due to PAT testing.

4)What ever happened to the law of 'current is the same in series'? When you touch an insulator, you are in series with it (if you are connected to the ground)?


texts: Output from a system of cascade connection with Wilkinson's divider and Quadrature hybrid

texts:
So I have this system, with

\$f=3GHz\$

\$b = \frac{λ}{4}\$

\$a = 0<a<b\$

and I want to know the output at ports 2 and 3.

I'm wondering how exactly I should approach it, and if my sketch is anywhere close to the truth.

simulate this circuit – Schematic created using CircuitLab

I'm wondering if I can consider the schematic in parts, or if I'm forced to consider all components at the same time, and if there are some shenanigans (like transformations) that I need to perform first.


texts:
I have bunch of 18650 batteries that are reading below 1.6V.
I tried charging one and the charger seems to charge it at 500ma. Should I continue or am I just wasting my time because it won't hold the charge? I head that below 2.8V batteries are considered dead.


texts:
When reading through the FTDI FT232H datasheet, I saw that the device can be configured as a "FT1248" slave. To me, the protocol they outline looks exactly like half-duplex 2/4/8-bit parallel SPI.
Am I missing some key difference? Does anyone have any experience in interfacing the FT232H with a microcontroller in multi-bit parallel SPI?


texts:
I got this rfid reader today and it dosnt seem to work.. as i understand, if i connect it's tx to arduinos rx, it should give me an STX value of 02h. Or something like that..
So.. How is this supposed to work exactly..
My code is

int incomingByte = 0;

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

void loop() {

    incomingByte = Serial.read();

Serial.println(incomingByte,BYTE);
  }

As i understand.. i should get a value.

The rx light is also not blinking..

Help!
Have connected everything besides the pin 2 and pin 3..
As required in the datasheet.. have connected an led which is glowing very slightly. And an Antenna.. I do have RFID tags which are supposedly 125 khz but cnt confirm. BUT, It is supposed to return an value to the rx?
Right?
I get an output of ÿÿÿÿÿÿ

Data sheet : Datasheet


texts: Why is the output from this regulator not a constant DC?

texts:
I have built a link switch.

The output is DC 5V but, when measured with an oscilloscope, itis not constant.

Why does this happen?

How do I get constant  DC   output?

Any design problem?

datasheet link switch

Output voltage:

Output wave form much noisy ..so i will updated soon


texts: How can I lower the Q factor for this filter?

texts:
I'm trying to make a 1MegHz CM filter using a common mode choke and some capacitors but I have a very high gain at lower frequencies instead of attenuation i.e high Q factor. A simulation shows the issue:

The filter is meant to filter 1MegHz or higher freq. CM noise from a DC output of a supply. But my fear is to damage the load because of a possible high gain at lower frequencies. How can I model it more realistic? I tried to add 1 ohm series resistors but it didn't help much. How can the Q factor be reduced in reality?

For the choke I use two of this ferrite core on top of each other with tens of turns. And here is the the actual photo:

Solution to the issue from the answer of @Andy aka:


texts: Monitoring of a System through an Arduino?

texts:
I am currently working on a project, where I will be doing the monitoring of a  mechatronic system through the following measures :

6 x Motor temperature (Digital Signal)
6 x Motor Current (Analog Signal)
6 x Motor Vibration (Analog  Signal)
6 x Spindel Vibration (Analog  Signal)
1 x operating time

And I was wondering if using an Arduino as a parallel real time controller to process and monitor all these measure in real time was a good idea and if it's professional?
By processing I meant detecting spikes within the measured data, saving data to an SD card(still didn't think of it properly), data exchange with another (company's) controller. The measuring frequency would be around 100 Hz.

And if not what would you suggest ?


texts: How can an electronics lab workbench be made feline-compatible?

texts:
I have a small-ish desk/lab workbench at my house with basic gear (meter, scope, PSU, etal as well as probes for same) as well as my PC and project stuff (boards, mostly, although a few parts-on-cut-tapes, boxes of parts, and loose wire bits too) on it. I rely on wrist straps (often used as improv ankle straps, but that's neither here nor there) for ESD protection (mostly when soldering or working directly with ESD-sensitive components) as I do not have ESD matting down, though.  Also, I do not have any high voltages exposed on my bench, nor do I solder on it as I keep my soldering iron packed up as I have to use the kitchen table for that job in order to not defeat the grounding on my iron.

My family is looking to acquire a cat, as well -- this won't be our first rodeo, but one hard rule I had with the last cat was "no cat on workbench" partly due to my concerns about cat fur and ESD (I've seen said cat get sparky with a bed comforter).

However, I was watching some of The Signal Path (i.e. Shahriar)'s YouTube videos and he lets his cat, Pooch(?), have free reign of his workbench!  So, how is it possible to make an electronics workbench feline-compatible?  Or, being a digital type (vs. Shahriar being an RF dude), am I best off sticking with "no cat on workbench" as a bright-line rule?  Are my concerns about feline ESD damage to boards misplaced?


texts: Basic Transistor Transconductance Amplifier - Negative Current Gain?

texts:
I'm working through The Art of Electronics. In chapter 2, it breaks a common-emitter amplifier into two stages: a transconductance stage and a resistive load stage (or transresistance amplifier). However, it states that the gain is

$$
g_m = {\Delta I_{out} \over \Delta V_{in}} = -1mA / V
$$

Why is the gain negative? I understand why the voltage gain is negative, but shouldn't the current gain be positive? E.g. a small positive voltage wiggle at the input would result in an increase in current at the output:

$$
if \Delta V = 0.5V then  I_{out} = 1.5V/1.0k \Omega = 1.5mA
$$

Where am I going wrong?


texts: Why do we need sheet entries and sheet symbol in Altium

texts:
I don't understand why we need to define some sheet entries and sheet symbols in Altium with multi sheet design ?!
Indeed, nets are already connected to each other by their ID from sheet to sheets as I understand or via Port. Why do we need to add on the top of this to describe Altium about sheet entries and sheet symbol architure ?


texts: Surface Mount Springs, how are they called?

texts:
We are currently in the process of creating Hardware-Test-Boards where we want to "plug-in" our PCB's and do a couple of tests. Our Boards have a rather complicated shape and are mostly surface mounted. Thus we have a hard and error-prone time to figure out, how to automate our tests due to connectivity issues.

Recently I found something on the Omega2s that would perfectly fit our needs.

The HDK of the Omega2s features those nifty little springs to plug in the sourface-mounted Omega2s which are holding it snug in place.
But we are unable to find those Springs on e.g. Mouser and Digikey.

How are they called? Where do I find some?

(We already have a footprint, just one hole and a long-hole).


texts:
simulate this circuit – Schematic created using CircuitLab

In above standard 3-ph IGBT based inverter circuit suppose Diode D4 is carrying current because of inductive nature of load. If corresponding igbt Q4 gets gate pulses in this freewheeling interval then whether current will  be transferred to igbt from diode as it happens in MOSFET called as "synchronous rectification" (which is used to minimize conduction loss because of diode)?
In short if PWM signal is applied to an igbt whose freewheeling diode is conducting will that igbt get destroyed/overheated?
 second doubt is if collector of a high side igbt is not connected to voltage source while bootstrap capacitor is fully charged then upon applying gate pulse to high side igbt it will get turned ON?

third doubt is if an igbt is rated for 600V 10A then can i operate that igbt at down to 1A or even below 500mA? also can i turn on it for collector to emitter voltage of 25V?


texts: Do electricity distribution companies charge apparent power (VA) or effective power (W)

texts: If there is a load connected to a power outlet during one hour, where average apparent power is 1000VA and average effective power is 800W, what will be charged by the eletricity distribution company? The VA power (apparent) or the W power (effective)?


texts:
I've developed a domino circuit which calculate a simple logic function.

I would like to latch the output "sum" into registers for further use. At the moment the logic goes to 0 during precharge as it should in domino logic.
I want to latch this output without violating the hold time.


texts: Is there a standard for maximum torque that should be used to fasten PCBs to an enclosure?

texts:
I am looking for a standard or guideline which describes how much torque should be used to fasten a PCB to an enclosure using different types of fasteners.

For example, we use M3 hex nuts in a system. There are ~25 people doing assembly. We do not want everyone to guess how tight the nut should be turned. We would rather give an appropriate tool to everyone and make sure each PCB is fastened the same way.


texts: Calculate Gain of Modified Band-Pass Filter

texts:
I would like to calculate the gain of this simple band-pass filter.

simulate this circuit – Schematic created using CircuitLab

What I'm interested in knowing is, in order to find this gain, would I have to set up a set of differential equations using Kirchoff's rules, or could I avoid this through some other trick? I'm particularly interested in the instance when the input angular frequency is equal to the characteristic frequency, $$\omega=\frac{1}{RC}$$

NOTE: I'm not asking for the answer, but rather for a hint a possible route to getting there (a trick). Also, if this question is not fit for EESE, then I apologize.


texts: ADC0808 IC working correctly only at times

texts:
I am using ADC0808CCN for a project on converting analog signal to digital signal. It has a built in multiplexer which we have to use to provide an analog signal to one of the pins. However what happens is:

Sometimes it latches to a particular value say 1000000 and remains at there no matter how many times start of conversion is pressed which should set the inner counter to 0.
Sometimes it gives slightly wrong output off by 100 or 1000 and when I press start of conversion, it gives correct output, so its not reliable every time.
And most seriously, suppose the control for multiplexer according to datasheet are such that input pin 1 should be active, instead, it works only when the input is given to pin 5 for one particular IC and pin 3 for other.

Since the frequency of 555 clock is 33Hz I thought switch bouncing would be not a concern, hence avoided it.

I have been trying to fit it in logic since 3 days however each day some new error happens. I have replaced it twice from my college lab and now the technician doesn't want to replace it anymore . What is amiss here ?

This is the circuit design taught to us for the similar ADC0804:

Since it doesn't use capacitors I ignored decoupling capacitors.


texts: Regarding connected circuits vs disconnected ones

texts:
so as i understand it, a circuit can be described using 'b' independent equations which are essentially written using KVL and KCL laws- where 'b' refers to the number of unknown currents in a circuit.
letting n= number of nodes in a circuit

We look for loops(meshes) and nodes as our big variables in any circuit, and through them, we can solve all the unknowns. Systematically, there are n-1 independent node equations (node voltage method using kcl) and b-(n-1) independent mesh equations(mesh current method using kvl).However, all of this talk apparently applies only to connected circuits which I'm still not exactly sure what it means. And then comes this little excerpt below which I'm not able to fully understand. The textbook suddenly and for the first time introduces the term 'part' along with disconnected circuits which made it confusing.

  The statements pertaining to the number of equations that can be
  derived from Kirchhoff’s current law, n-1, and voltage law, b-(n-1),
  apply to connected circuits.  If a circuit has n nodes and b branches
  and is made up of s parts, the current law can be applied  n - s
    times, and the voltage law b – n + s  times.  Any two separate parts
  can be connected by a single conductor. This connection always causes
  two nodes to form one node. Moreover, no current exists in the single
  conductor, so any circuit made up of s disconnected parts can always
  be reduced to a connected circuit.


texts: Read force sensors of the keys an existing electronic keyboard

texts:
I have a rookie question concerning making an electronic circuit.

I'm attempting to hack an electronic piano to read the keystrokes into an arduino and do stuff with it.
On opening the piano I found two pins per key that, when I put my multimeter to them, generate around 2 volt when the key is pressed.
So I soldered wire to these to connect to a breadboard (see picture 1).

The second picture shows the circuit I made for one sensor.
This works perfectly, I can "analog read" the force sensor; I get values of around 900 when a key is pressed, and values less than 70 when the key is not pressed.

However, when I connect a second force sensor (third picture), I'm getting the following problem:
When I press either of both keys, they both sound. When I disconnect their GND's, it's not the case anymore. So apparently a shared ground makes that generating current on one force sensor-circuit, also puts current on the second one, making it sound?

Pressing one key also makes the second sensor read 250 even though it's not pressed.

I guesss I have to separate some things somewhere, but I have no idea what. Or should I put a diode somewhere in there?

I hope I'm making this clear.
Thanks in advance for any help!

PS. I don't need the velocity of the note, just whether or not it's pressed. If all else fails I'm gonna try and connect push buttons to the keys but I'm sure there's a way to hack into the existing circuit...

Figures


texts:
I'm currently reading an application note about paralleling MOSFET and oscillation and it is written the following sentence :

"In addition, parallel MOSFETs share a common low-impedance path, which is also susceptible to parasitic oscillation."

What does it mean by low impedance path ? And why there is a low impedance path ? And why a low impedance path is susceptible to cause oscillations ?

Here is the application note (the sentence is written page 4):
https://toshiba.semicon-storage.com/info/docget.jsp?did=59458&prodName=TK8P65W

Thank you very much !


texts: How do you use ICs in your own projects that don't come with a datasheet?

texts:
Is it possible to use ICs in your own projects that don't come with a datasheet, by reverse engineering or ordering the datasheet somewhere, for example the IMX260 CMOS image sensor from the Galaxy S7?

I mean the IMX260, the L2G2IS gyroscope and [W25Q32FW][www.winbond.com/resource-files/da00-w25q32fwa1.pdf] serial flash memory chips on the left of the camera actually have public datasheet.


texts:
I learned that QSPI chip from Micron N25Q256A13EF840F is getting obsolete. I found a similar device MT25QL256ABA1EW9-0SIT from Micron. It did not work when I replaced it on a board. It does not even give me the manufacturer ID
Is  N25Q256A13EF840F drop-in replacement for  MT25QL256ABA1EW9-0SIT ?

Below is the datasheet link for N25Q256A13EF840F
https://www.micron.com/-/media/client/global/documents/products/data-sheet/nor-flash/serial-nor/n25q/n25q_256mb_3v.pdf

Below is the datasheet link for MT25QL256ABA1EW9-0SIT
https://www.micron.com/-/media/client/global/documents/products/data-sheet/nor-flash/serial-nor/mt25q/die-rev-a/mt25q_qljs_l_256_aba_0.pdf


texts: AVR: why reading data have some delay from writing it in SRAM (Timing diagram)

texts:
In that timing diagram we see that the write command in the same time nearly with the data. Why we don't see that also in reading data and why there is that delay between data and read command?

That is screen shot from ATmega328 datasheet page 36


texts: Powering a 2 watt 6 ohm speaker with a 9V battery?

texts:
Im very new to electronics and what Im currently doing is my first project. I want to make a tiny guitar amp using a speaker I salvaged from an old computer speaker. The speaker says 2 watts 6 ohms on it. Ive researched online and found it probably means 2W rms but it could mean peak too. Since the speaker is so tiny itd be really cool to make the amp battery powered with a 9v battery if possible. I did some calculations and I hope theyre good lol.

I think the rms voltage for 2W of power should end up being the equivalent to around a 4.9V amplitude, which is a little more than what the 9V battery can provide.

the current for 2W is around 0.58A, which I read would deplete a 9V battery in an hour.

I dont understand wether the speaker needs 2W of power to even work, or is that a maximum amount of power it can handle? will the speaker always "try" to draw the current needed, or can I adjust how much current it gets with other circuit components (when designing the circuit it says "choose a quiescent current", does this mean I can somehow set how much current goes from the battery?). Is 2W just for the loudest about the blow the speaker volumes and can it run normally on less power, and if yes, how to provide less power?

Edit: Its a common emitter amplifier circuit, R5 is the speaker

Edit: Id like to keep this circuit as simple as possible since it took me a long time just to understand emitter amplifiers haha, Im very much using this project as a beginner learning project.

Edit: Ill use an lm368 op amp instead of this, I see that this sucks now


texts: Remote pan a 2.7m carbon fibre camera pole

texts: I am building a pole camera, normally you would have someone on the other end to move the pole, but we want to be able to operate it remotely. As the movement needs to be very smooth, with a soft start and soft finish, some sort of dampening needs to be added into the pole motor movement. The pole itself will be about 2.8 meters long, with a lightweight HD PTZ camera at the end. I'd like to be able to have control over the current position of of the pole, no need for tilt, only for pan, as well as setting presets, and auto move. Auto move would be something like setting limits to the pan, and having the pole move in a sin wave side to side. I'm thinking something like an arduino for the control, but uncertain of what would be good mechanically to move the pole not only with precision, but also be very strong, as we often get very high winds.


texts: What is the equivalent LTSpice diagram of the given varactor diode modulator (FM)

texts:
Given below is an example of direct FM generation using varactor diode modulator.
What is the equivalent circuit of this in LTspice?
Can you explain the given circuit?


texts: Motor acting as a generator with backfeed

texts: 12v DC automotive question.  I replaced the engine-driven clutch fan with an electric radiator fan, controlled by thermostat and relay.  I included an LED in the vehicle to show when the fan is ON.  Everything works fine most of the time, but I find that when vehicle speed gets to around 55 MPH the LED is coming on even though the engine temp should not be triggering the thermostat.  I'm convinced that the fan is being driven to turn (freewheeling) by the relative air at speed and the fan motor is generating current back into the system.  Is there any ill effect of letting this condition persist, e.g., reduced fan life due to the heat by-product of the generated current, damage to other electrical components.  If so I could add a switch to control it, or a diode but I understand a diode will limit the voltage to the fan when running in normal mode.  Thanks.


texts: Tektronix TBS 2000 oscilloscope to Python

texts:
I am a total beginner when it comes to communicating to your electronic devices using python.

I installed PyVISA, Open Choice Talker Listner (Tektronix), a few other items.

I was able to send basic commands to TBS2000 series oscilloscope using "Open Choice Talker Listner" as shown in the image below.

I was googling 'how to control your oscilloscope using python' but have not been successful so far.

I use Anaconda.

I guess there's plenty of information available online but for a beginner like myself, its been posing a huge mountain to climb.

Would anyone be so kind as to point me in the right direction of where to find such information, and maybe even post a simple script as an example?


texts: Fuses - Are there any voltage conversion for the break-off

texts:
Anyone knows the very common glass fuses in electronics etc. But I am uncertaion about the breaking conditions.

Example: A fuse rated as 5A/250V, it is the breaking point. But I have seen such used in devices with a much lower voltage, like 12V or 24V.

The breaking of the fuse is based on a maximum energy generated as heat to melt the internal lead by Ohm'S law, aka P = UxI.

But this does not correlate with the current (A) at different voltages. In the example, the nominal is P = 5A*250V = 1.250, which used with a 24V case, would be (I = P/U) = 1.250/24 = 52A which is way beyond the rated 5A.

In other words: We have different currents at different voltages to generate the same energy, if we are to follow Ohm'S law and that the breaking requires the same energy in any case.

This is a little confusing, because it must be the current that are the dominator and the current is driven by the voltage, so the voltage is certainly a factor...


texts:
I am building a circuit using the ESP8266-01 and a temperature sensor. For the final test I am using a 9V battery and I have many questions:

The 01 version only have two pins to read, but the GPIO0 should be grounded when programming, therefore how can I connect something to that pin? Putting in the code, placing in ground and then to the other sensor?
The other question is related with measuring the battery left in the 9V battery. How can I do it?I am going to explain the situation:

The data of the sensor are uploaded to thingspeak and I though in show a webserver with the battery left, accessing through the IP of the ESP8266. Can this be done? Also I think that knowing the total voltage (9V) and the current voltage can be know the % left in the battery, isn't?

Have Anyone tried this and could share what do you think about doing it?


texts: Creating a programmable gain amplifier with a digital pot and an op amp

texts: I wanted to create a PGA using a single supply op amp and digital pot. I hooked up my circuit like below, but my signal is getting attenuated with Rwb = 200 ohm and Rf = 1k. Are there any problems with my setup?


texts:
I want to use a 9.1V Zener diode for a ref voltage into a op amp comparator so that when the battery voltage (11-12V DC) drops below 9.5V DC it will cut the supply to the circuit via a P-channel MOSFET.

The supply voltage will go through a voltage divider dropping it by 10% so when it hits the magic level it will still be above the Zener voltage and cause the comparator to drive the gate of the MOSFET low and turn it off.  Thus saving my batteries from harmful deep discharge.

Will this work or is there something I'm going to get bitten with?

simulate this circuit – Schematic created using CircuitLab


texts: When a wind turbine does not produce enough electricity how does the power company compensate for the loss?

texts: I heard once that when a wind turbine power plant doesn't produce enough electricity the power companies are sometimes forced to turn on a couple of jet engines in order to compensate for the loss, is there any truth to that? I imagine stability is a key factor in keeping the production static and efficient, so what would the power company do?


texts: Can I replace rechargable batteries with (super)capacitors?

texts:
I need a very small UPS just to give an embedded device time to shut down when power is lost. There are a variety of solutions that use LiPo batteries to provide extended runtime; they typically take USB input and manage both the charging and failover to battery on power loss.

Can I replace a single-cell LiPo (nominal voltage 3.7v) in a charging circuit with a pair of 2.7v supercapacitors wired in series and have it mostly "just work" assuming that (a) there is already some sort of current limiting in place on the charging circuit and (b) I include a passive balancing circuit between the capacitors?

In this situation, I would be under-charging the capacitors (to 3.7v, vs the combined 5.4v capacity in this example). What impact does that have on their behavior?


texts: Transfer function of a summing integrator

texts:
I'm trying to derive the transfer function of a summing integrator for use in a feedback circuit. The single input and double input integrators are shown below.

An integrator with one input is derived such that:

$$V_{\text{OUT}} =  -\frac{1}{RC}\int V_{\text{IN}}dt$$

For gain in the frequency domain, this becomes:

$$\left\lvert\frac{V_{\text{OUT}}}{V_{\text{IN}}}\right\rvert = \frac{1}{\omega R C}$$

So because at the negative terminal of the opamp, these input voltages are summed, the summing integrator transfer function is:

$$V_{\text{OUT}} =  -\frac{1}{R_{\text{fb}}C}\int V_{\text{fb}}dt - \frac{1}{R_1C}\int V_{\text{IN}}dt$$

My question is, in the frequency domain, does this simply become:

$$\left\lvert\frac{V_{\text{OUT}}}{V_{\text{I}}}\right\rvert = \frac{1}{\omega R_{\text{FB}} C} + \frac{1}{\omega R_{\text{IN}} C}$$

Where \$V_{\text{I}} = V_{\text{FB}} + V_{\text{IN}}\$ and the output is 180 degrees shifted (90 degrees + 90 degrees).


texts: Bipolar RC Oscillator does not oscillate

texts:
Falstad schematic and simulation

VCC is 9V.

I made hardware version of this first (didn't put too much effort in this simulation) and it's not working. I could read about 3-4 V on CE, so transistor was partially open and seems that it was around Q point. I used 8550 transistor (not sure what D611 under 8550 means).

What could be the reason here? Maybe too small capacitors, maybe too high RC resistors, or maybe ill-suited transistor?


texts:
I've been programming microcontrollers for a few years now, and I've just discovered FPGA's after taking a digital design class. After doing some research into different FPGA's, development boards, etc, I'm still hesitant to buy any because I wouldn't know how to make my own version of the final "product." I've put PIC's, SAM's, AVR's, etc. on to custom PCB's with no issue, so I'm not worried about that--my main concern is programming an FPGA without a manufacturer's board.

My specific question: Would an FPGA function if I took the bitmap file generated by Quartus, Vivado, iCEcube, etc, wrote it to an SPI flash memory chip beginning at address 0 (say, via an FT2232H), and connected the flash memory to the SPI pins of an FPGA (with the MODE config set properly)?

I apologize for the partial hypothetical; I'm fairly sure that's all Lattice's Diamond Programmer does, but I wondered if that approach would work for FPGA's from different manufacturers, or whether say, Quartus added additional "window dressing" or headers to the memory while writing it.

Let me know if there's anything I can do to improve/clarify the question, or if I'm missing a big point in the FPGA programming process. Thanks!


texts: What is the math behind high FM frequency components being more noise prone?

texts:
what is the math behind the phenomena that higher frequencies are more prone to noise?

The use of pre-emphasis to boost the higher frequency components to get a better S/N ratio.

Can you provide the math behind why the higher frequency components are more prone to noise?

Thanks!


texts: Suspicious diagrams depicting PGT of D flip flop

texts:
I encountered a designing problem in digital system:

Add the necessary logic circuitry to accommodate the
transfer of data from memory into the A register.The data values from
memory are to enter the A register through its D inputs on the PGT of
the first TRANSFER pulse; the data from the sum outputs of the full adders
will be loaded into A on the PGT of the second TRANSFER. In other
words, a LOAD pulse followed by two TRANSFER pulses is required
to perform the complete sequence of loading the B register from
memory, loading the A register from memory, and then transferring
their sum into the A register.

When I tried reading the solution, the text introduced a D flip flop, which I thought it depicted falsely regarding the active transition (which is PGT, not NGT)

Is the book's solution right? Or does it need correcting?


texts: Should an unused VCC pin with a higher voltage be left unconnected?

texts:
I'm trying to integrate an ESP32-PICO-KIT/V4.1. into a small project.

The documentation for the PICO power supply says this:

  There are three mutually exclusive ways to provide power to the board:

  1) Micro USB port, default power supply

  2) 5V / GND header pins

  3) 3V3 / GND header pins

  Warning

  The power supply must be provided using one and only one of the
  options above, otherwise the board and/or the power supply source can
  be damaged.

I have chosen to power the board with a 3.3V supply coming from a linear regulator.  The PICO board has two pins for 3.3V, and I have connected each one to the 3.3V Vout leg of the regulator.  I've also connected a 0.1uF capacitor next to each 3.3V pin.

My question is about the 5V pin on the PICO.  It will not be used.  Should I leave it unconnected, tie it with a large pull down to ground, or do something else?  It's not an input pin so I'm not sure what to do.

Thank you!


texts: What Bluetooth 4.0 devices and radios are available?

texts:
Bluetooth 4.0 is the latest specification to be adopted by the Bluetooth cabal, which notably adds Bluetooth low energy into the mix, which is designed to allow radios that sip battery like 802.15.4 ("ZigBee") to directly connect to consumer devices.

It sounds great, and according to a search for "bluetooth 4.0 devices", we are swimming in them because they all showed up Q4 2010, however I can barely find more than a single chip (TI CC2540), let alone any consumer product that is BT 4.0.  Where are they?


texts: Anyone know of a good/cheep usb dongle to pick up ULF (.3 - 3kHz) radio?

texts:
I've bought a pack with 3 temperature senders and 1 receiver. But I want more, and I also want datalogging.

Is there a USB dongle that let's me pick up on a given frequency, lets say '433.92 Hz' and sniff up whatever floats "in the air" as the senders send the temperature every minute or so to the receiver?


texts:
I have some questions about nand memories.

Do we need to erase whole block to rewrite only one page?
If true, what is the algorithm? Cache whole block > edit one page > erase whole block > write whole block?
How random data input works? Do we need erase block to input few bytes in random mode???

p.s. I am writing MSD application with STM32F207ZG mcu + K9F1G08U0B nand

EDIT For newbies like me

How NAND flash works:

We can perform read and write on page basis or use random input or random output in any page. Nothing special about reading, but i hear that reading, like writing, may wear pages.

After erase all bits in erased area is set to 1, and when we write, we only set some bits to 0. Once bit is set to 0, it cannt be set to 1 again, setting bit to 1 is possible only by erasing region containing that bit. As consequence, if we need to fill some region with 0x00, we do not need to erase this region.

And note: Erase can be performed only on block (not page) basis. I found, that when you specify page address to erase, block containing that page will be erased. So we need to specify not a block number to erase, but for example number of first page in block.

Hope this information is correct and will be helpful for someone. Sorry for my broken english ;)

Thanks to supercat for explanation.


texts:
I'm attempting to complete the question below.

What I understand so far: The circuit can be modeled with an 'equivalent inductor' and gain stage (not sure if this models the whole circuit or just one of the opamps). Leq is the equivalent inductance.

My confusion boils down to needing these two questions answered:

Does this equivalent circuit model the whole gyrator or just part of it?
How do I get started with showing that sLeq = R1R2C?

My course has given us no example answers, no similar questions in tutorials, and the lecture notes are not very detailed so I am a bit confused. Any help would be greatly appreciated.


texts: Soldering Header Pins Together to Multiplex Single Digit 7-Segment Displays

texts:
To multiplex two or more single digit SSD’s, each corresponding pin must be connected to that of the other displays, such as in this schematic.

I’ve accomplished this with 4 displays by using a daughterboard with pin headers, which I then connected to the displays with jumper cables. It was a little messy with so many wires. And I could have easily just used a 4 digit dynamic display.

I need to multiplex two of these single digit displays now. Finding a pre-made dynamic two digit display in the color and size I need (green) hasn’t been easy. So i’d like to just “make” the two digit displays myself. After all, I don’t need just one of these two digit displays for my project, but 4 of these in total. That would be 4 daughterboards.

My idea now is to attach the two displays adjacent to one another on pin headers, then solder cables directly, pin to pin.. This way I don’t need the daughterboards and can save some space.

How would you go about soldering cables to the headers? I’m thinking just wrap the cables once around the header, then heat and bring in solder.. Or is there a better alternative?

Wire wrap also comes to mind, but those factory made wire wrap headers are expensive.


texts: I want to switch a 24V DC water pump by a 5V DC from an Arduino. I think the best way to do it is by a logic level mosfet low side switching. To do so, the \$V_{DS}\$ value should be 24V or a much lower since most of the voltage drops on the load (water pump)?


texts: HD44780 in 4bit mode connected to only ONE PORT on PIC

texts:
i am new to PIC programming. I am using MPLAB X + XC8 compiler. I have on a breadboard an PIC18F4550 connected to a HD44780 compatible LCD. Digging online i found out a routine to interface the PIC with the LCD controller, works ok on 8MHz internal osc.

LCD is connected to the PIC like this:
RB0 = D4
RB1 = D5
RB2 = D6
RB3 = D7
RD5 = RS
RD7 = E

In my code, all PORTB is used for Data lanes and from PORTD only RD5 and RD7 are defined for RS and E.

My question: How can i move RS and E pins to PORTB also , so the LCD uses a SINGLE PORT, not 2 ports. . Because if i define for example RS as RB4 and E as RB5 , the code that toggles the DATA lines is like this (PORTB = data_to_send) , so it toggles all PORTB pins , not just RB0..RB3 . How can i address/toggle a pin range (RB0..RB3) of a PORT and not the whole port?


texts: Why USB power banks tend to have much larger capacity than cordless tool batteries?

texts: I have a 10000mAh battery pack for charging phones/tablet/whatever but I also have some cordless tool batteries which can be used in an inverter to power a usb charger similar to the power bank. The cordless tool batteries only go up to 5Ah (I think you can get larger ones but they’re not very common) and that on it’s own is far larger than the power bank as well as having a lower capacity. I assume it is to do with the batteries being 18v rather than 5 or whatever the power bank is?


texts: Can I reduce energy consumption if I disable accelerometer's axes?

texts: I'm using LIS3DH accelerometer, a 3 axes accelerometer to build a low energy consumption device. For now I just need the Y axis. If I disable X and Z, can I save more energy or the accelerometer use the same amount of power?


texts:
I want to run 5 Vishay TSUS5402 LEDs continuously, but I'm not sure what the voltage and current should be. The datasheet is here:

https://www.vishay.com/docs/81056/tsus5400.pdf

I can't really see on the datasheet anything about continuous use, only pulse. Thanks for any help


texts: What's a good ferrite material for broadband transformers in the UHF band?

texts:
I need a single hole tube shape, that I can use up around 500 MHz.
I've not found anything beyond 300MHz on Magnetics Inc, Fair-Rite etc.
I need a cylinder shape with single central hole, OD <7mm, length non-critical.

I mention the shape because it's important in my application, and I've noticed a given material may only be available in certain shapes.

I remember seeing something like this used in UHF TV applications, probably in matching 300 ohm twinlead, and that would certainly cover the range I need.


texts: In AM modulation how is an electrical signal mixed with the carrier wave?

texts: I may have the wrong stack exchange to ask this beginners question. Should this be a physics question?  The interference of waves constitutes the addition and subtraction of wave forms. In AM modulation a voice signal is somehow "mixed", "superimposed", "modulated", "coded" with a carrier signal. I have heard it described in those four manners.  I assume it is not interference of two electrical wave signals and cannot be an addition. There lies my problem. Can someone first explain. Is the electrical signal in the wire in the form of an electromagnetic wave? and How are these two separate signals  ( i.e. one being a carrier wave and one being a signal from a voice ) modulated together?  I cannot understand how this is physically done nor a mechanical analogy to this as I can with wave interference.  Thank you.


texts: Need help on picking a right type of p channel mosfet to light up an LED (as per attached schematic)

texts:
HI All,

Can you help me to chose a p channel MOSFET that can do the job of turning On/Off the LED with an input from VSF6 which toggles between 0 & 1.8V? Appreciate all the technical gurus help.


texts: Layout polygon pour connect to GND or VGND noise reduction

texts:
I am using MCP6V02 as transimpedance amplifier as shown below schematic, I want to know is it better to connect polygon pour to GND or VGND to reduce noise on the amplifier. (Below schematic is for simulation)

simulate this circuit – Schematic created using CircuitLab


texts: Predicting decay time of a resonant bandpass filter?

texts:
In a typical resonant bandpass filter, resonance is set as none at 0 and full at 1, such that the filter rings infinitely at 1 and not at all at 0.

If there is a two-pole resonant bandpass filter, with an impulse excitation to a maximum amplitude of "1" and resonance setting between 0 and 1:

What is the mathematical equation that would allow you to predict the decay time of the resonant filter based on its resonance setting? For example, to an arbitrary level of "1/e"? ie. To 36.7879% its original amplitude?

Thanks.

Update June 3, 2018 @ 5:17 PM

Thanks to some good answers below, I now better understand the problem as follows:

I need an equation to solve for Q or ζ of the filter based on an input of time (where that time represents seconds to reach 1/e amplitude relative to a starting 1 amplitude).
The bandpass filter will only be needed in an "underdamped" condition, ie. Q>0.5.

Thanks again. This has been very informative and I think this should be a clearer and more answerable question.


texts: Where to order small batches (say, 100 units) of custom boxes for your projects

texts:
I'm creating a simple effect for musical instruments and I'm wondering how I will package it when it'll be ready. I mean, I can create some kind of stomb box with my own hands but if I'm ever going to sell it I need to find a way to create some small batch of them. The problem is it's hard (impossible?) to find some manifacturer who cares of building, say, 100 boxes. On the other hand I cannot order thousends of them because I'm not sure I'll sell the out.

So has anyone faced/solved this problem in the past?
Thank you very much ;)


texts: How to apply if-else condition of inputs and display the output on 7 segment display on Proteus

texts:
I am fairly new at using Proteus. This is my second time using it. This is not a homework question. I am trying to figure out, if i have 7 doors leading to a vault and 2 are main doors, 5 are internal doors. if any of the doors is opened i will turn the LED to green. and display on the 7 segment display which door was opened. i know for a logic diagram i can simply OR all the inputs and attach an LED, but how would i display it on a 7segment display.
I just want an algorithm or any basic hint not details. just where to start. Thanks.


texts:
I never quite understood why negative feedback is more used than positive feedback.

Using feedback makes it possible to adjust the gain, and thereby specify how much the input should be amplified.

But why is negative feedback more commonly used when we want to amplify small voltages from sensor readings such as photodiodes etc.

The output of the op-amp becomes the negative amplified value of the input (input and output has different polarity), which don't make sense why it should be useful..

Hence would i always use positive feedback, but I can see that the internet disagrees with me, so must be wrong somewhere in my "reasoning" so what am I doing wrong?


texts: Type 1 surge protection: parallel or series?

texts:
Type 1 surge protection devices (SPDs) are installed at the outside edge of electric service, usually between the power meter and the meter base/socket, and protect the entire house.  But how do they work electrically?
SPD types 2 and 3 work entirely in parallel with the protected devices; when there is a surge, the SPD basically loads the circuit to draw the voltage back down.  Do Type 1 SPDs work this same way, or is there also a series aspect to their operation?
I seem to remember reading that a Type 1 SPD can create some isolation between the house and power line.  In other words, it would absorb the surge voltage between (in series with) the line and the house.  Is this the case?


texts: The new RF frequencies are 868 MHz for Europe and 915 MHz for the US. I heard 433 MHz is barely regulated, read: it's chaos. Then why are 433 MHz RF modules still used? Are they cheaper to produce?


texts: Understanding OSI Communication Model in Hardware

texts:
I have gone through the OSI communication model and the associated levels.

But I do not understand on how is this implemented in the Hardware level. Or let me put it like this.

Suppose we have a USB (2.0 and 3.0) communication device from my Host PC to a Device connected. Like, from the hardware perspective, I can understand and try to design the circuit connection between the host and the device. This is just the physical layer, right?

How to understand the datalink, network and the higher layers from a hardware perspective?
Like, does each data bit or say packet of bits get filtered by the host controller during its processing stage? I know the previous line does not make sense. That's where I am stuck.

If someones says, (for example, take I2C communication) that something is taken care at the datalink layer, what does the datalink layer actually do when they say this or what do they mean?

Simply put : What happens in the electronics level or the IC level during each stage of the OSI Communication level.

How does a Hardware Engineer understands this?
Please help.


texts: Issue powering up a DC water pump with Arduino Uno

texts:
I'm having issues powering up a water pump I got from a little water fountain with an Arduino Uno. I don't have the reference of the water pump, but after testing it, it works perfectly well with 5V and it requires between 100mA and 150 mA to be effective enough.

If I power the pump using the Arduino Uno 5V Vcc (not Vin), it works quite well, but as soon as I add a resistor in serie (to limit the current), it stops working, even if the resistor is as small as 33Ohms (which should top up the current to 150mA). I also notice that voltage drop to approximately 2.5V around the pump itself when I add the resistor (4.6V when mesuring around the resistor AND the pump). I studied electronics a long ago but I don't get why it behaves this way.

If you have any idea or explanation, I'd be glad to hear it, thanks !


texts: Calculating the absolute margin of error of a circuit

texts:
I need to calculate the absolute margin of error of a measuring circuit that is composed of a DAC and an ADC. The DAC (MCP4725) has a margin of error of +-2 LSB, and the ADC (ATMEGA328P) has a margin of error of +-2 LSB. Keep in mind that the resolution of the DAC is 12-bit, and the ADC is 10-bit.

I looked and I found about "error propagation", which seems to be the most viable solution to this (assuming that the error for each IC is the margin of error divided by the resolution).

Thanks!


texts: How to run a DC device through 3 phace 400V AC mains?

texts:
So I need to put a wifi antenna on farmland, the issue is that the antenna needs 12V DC  powered over Ethernet and the only power source nearby is a 3phase 400V AC one...

So is there something like a full bridge rectifier I could buy to do that or an other sort of converter/adapter?


texts: Prove that in a *nonlinear* circuit, adding resistor between equipotential terminals draws no current

texts:
If a circuit is linear, then you can use Thevenin equivalence to prove that if a port of a circuit has an open-circuit voltage of 0 V (the two terminals are at the same potential), then the resistor will not draw any current.
What if the entire circuit is nonlinear? Intuitively I think the fact still holds but Thevenin equivalence can't prove it anymore. Is there a counterexample to this?


texts: High voltage Dickson charge pump switching

texts:
I am working on a circuit based on the LT1930 (DC634A) to boost input voltage between 30 and 90V.
I would like to take this boosted voltage and double it via a Dickson charge pump to the required ~160V.
This would allow for a variable voltage output between 60-180V. The current draw from this boosted supply is very low, ~1uA.
A logic level PWM signal will drive the Dickson charge pump.
I am having difficulty figuring out how to drive the boosted voltage through the C1 based on the PWM clock. I have setup a NPN driven by the PWM signal to switch a PNP MOSFET to high side switch the boosted HV.
When I run simulations, the output voltage does not double.
R1 and R2 are set to give a Vgs ~10V, but then this causes the drain on the FET to only vary between 80 and 70V.
I am open to suggestions, including completely wiping this circuit and using something else to generate a controllable ~100-180V.


texts: Blinking LED on MSP430 with three conditions

texts:
I was designing a circuit which must satisfy  conditions.

LED2(green) should blink at 2Hz 50% duty cycle


texts: I am planning to build a Furuta Pendulum. I have a mini-servo motor (SG90 Mini Gear Micro 9g Servo RC). Within the scale shown in the video, is this mini-servo motor sufficient for this application?


texts: how much time it will take to fully charge a 48 V 35 Amp hr battery using a 100 V DC dynamo running at an average speed of 20 km/hr

texts:
The above mentioned dynamo is being used in an e bike.
i have tried to go through many sites but didn't get a proper answer.


texts:
Can anyone suggest how i could switch this resistor ladder with the smallest possible footprint.  I was looking up analog switches but not sure if thats the right way to go.

The circuit tells an ecu what speed to run the engine at, and states the resistor tolerance at 5%.  I am looking to control this circuit with an mcu and would like suggestions of what sort of IC could be used as a switch.  it would have to have a low Ron (6ohm) to keep in spec with resistor tolerance.

Thanks in advance


texts:
simulate this circuit – Schematic created using CircuitLab

I am using an LM324n opamp with dual supply in the circuit as shown with ADC and DAC ports of an Arduino Due board.

I am getting the expected voltage output range of 0V to 3V at the ADC which I give to DAC. Since the DAC voltage range is different from ADC, I used the amplifier circuit in the dotted box as a rectifier to get 0V to 3V output range which is then given to another amplifier circuit whose output is connected to the input as feedback.

Since I am not using any external current source I am expecting 0V when connected as a closed circuit but unfortunately I am getting 1.62V to -1.64V  for the input range as shown (1.65V to -1.65V at non inverting terminal).

Is there any reason for this, and can anyone suggest how to rectify this if there is any way? Is my assumtion of 0v output for closed circuit  correct?


texts: Why does out command works wrong? (Proteus 8086)

texts:
I am trying to create an output unit for 8086 microprocessor which is connected to MP's 00ABh(10101011) address. I used 74LS373 for that. This is how I made connections:

When I run the code below, LED's shows the address value (00ABh) instead data value (18h).

What am I doing wrong here?


texts: Signal low delay for specific amount of time / hardware - equivalent of Arduino pulseIn() function

texts:
I have a circuit similar to the following:

(Source: electronicsforu.com - Shadow Alarm: Light Sensitive Circuit)

In the circuit, the output from op-amp pin 6 goes low when a shadow falls or light is not present.

I am using this to find out if an obstacle is present or not and it can be done only this way, according to our constraints. The obstacle blocks the light and so the voltage from pin 6 goes low. These are moving obstacles with a certain width, so the light is blocked until the width passes and this width is constant. However we have smaller obstacles in the same line which we should ignore, based on the width.

In simpler terms, if the light is blocked (voltage is low) for only for 20 millseconds, then we have to ignore it. However if the light is blocked (voltage is low) for more than 40 milliseconds, then it is a valid obstacle. I have to do it only with hardware, not using functions similar to Arduino pulseIn() etc.


texts: adapter between thicker and thinner AWG wires

texts:
I'd like to connect two different AWG wires, sizes 18 and 24. Preferably made specifically for outdoors underground usage.

More to the facts, the 24 AWG is part of a 8-wire CAT 5E cable that I need too tuck into some irrigation valve connectors which is not supposed to be taking in the valve's thick wire and the thin 24 AWG wire together. This is what I am currently doing and I am having only trouble.

What sort of adapters should I be looking for ?


texts: How to measure the actual length of a long twisted pair?

texts:
Sometimes we might need to know the exact length of the wire pairs inside a cable. One can be interested in calculating voltage drop or some other calculation regarding the exact length.

Because the wires inside the cable are twisted, their actual(electrical) length is greater than the cable jacket length.

Is there any practical method to calculate the actual length?

I couldn't find a duplicate, but if there is I will delete this question.


texts: What type of component would be required?

texts:
I apologize in advance if this is the wrong place to ask the question.  Although it does in someway relate to electrical engineering, at the product level, i am sure. Basically i am trying to figure at the feasibility of a starting product that i might sell.

The product would basically be a car door magnet as illustrated here: http://www.vistaprint.co.uk/car-door-magnets.aspx?&GP=8%2f8%2f2013+9%3a03%3a56+PM&GPS=2921082194&GNF=0.  My question is what kind of electrical component would be needed that could somehow record the moment the magnet becomes detached from the surface?  What name is given to such a device, so i can further research it?


texts: How to use electrolytic capacitors in Orcad Capture

texts:
I want to specify voltage across the electrolytic capacitor in Orcad but there seems to be no way to this.
I'm using C_elect part and the panel to choose the value is below:

I've tried this formats but none of them worked: 1u 16 1uF 16V


texts: how to determine architecture core detail of ARM11 processor

texts:
I'm cross-compiling for an embedded Linux board, based in BCM5892 ARM11 processor.

I need to know about architecture detail of this processor(‘armv6’, ‘armv6j’, ‘armv6k’, ‘armv6kz’, ‘armv6t2’, ‘armv6z’, ‘armv6zk’) for feeding  -mcpu flag for compiling my application, but there is no such information in Broadcom website and manufacturer does not provide any information too.

then is there any way for determining this information from Processor or OS?


texts: Advantage of using AC generators in cars instead of DC generators

texts:
Most cars use an AC generator then convert its voltage to DC via a bridge diode rectifier to charge the 12v battery.

Why wouldn't a DC dynamo be used instead?

Is it because AC dynamo gives better efficiency?

(Even bike and wind energy use AC dynamo/turbine).


texts: How to eliminate the Miller effect on BJT BC547?

texts:
I have an application:

The input in a 3V train pulse @ 100Khz
I need an Ic to be 10mA for the LEF of the optocoupler.

I am using BC547C:

Input Capacitance= 9pF
Current Gain Bandwidth Product(hFE)=400.

The problem is the Miller effect, it will make (Rb+CM) act as a low pass filer at10Khz if m calculation is right.
Miller effect info

How can I solve this problem
Are their another way to get my desire output ?

Is this circuit with mosfet will work ?
I could change the LM231 output  from 5V to 15V.

The lm231 circuit I used is at page 10 in this datasheet


texts: Eagle component went to bottom layer but should be on top

texts:
I defined a device (MOSFET) using the schematic and package from other components and placed 4 in my schematic.  When trying to route connections, these parts can only be interconnected using bottom traces even though they were placed and appear as top layer components (red, not blue).  If I mirror the component, it turns blue and I can connect top traces (red) to the blue component.

What have I done wrong that would make this happen?


texts: Problem in overflow detection in signed 2's complement 3-bit numbers

texts:
According to this page, and other similar ones, the rules for detecting overflow when adding signed binary numbers in 2's complement form are the following:

If the sum of two positive numbers yields a negative result, the sum has overflowed.
If the sum of two negative numbers yields a positive result, the sum has overflowed.
Otherwise, the sum has not overflowed.

This, however, appears not to work for 3-bit signed numbers. For example consider adding -2 and -2, +2 is 010 and it's 2's complement is then 110. Then -2+-2 = 110+110 = 1100. When we discard the carry, the sign of the number is negative, because -4 can not be represented as a 3-bit signed number. I am trying to optimize a design for a school assignment and currently the best I can do is just handle the case where it gets to 100 (I just turn the overflow flag on if this happens). Any help is much appreciated.


texts: Wiring 2 audio output transfomer secondaries in series or parallel

texts: I want to know if wiring 2 audio output secondaries in series is doable.  See problems with this schem?  Would parallel be a viable alternative?


texts:
I have an old DB-9 connector (Male-to-Female). I cut it in half, to find 6 wires inside. 5 Had colored insulators and one was a strand of naked wires.

First question: isn't it supposed to have 9 wires instead of 6?
Second question: which pins do those wires corresponds to? Is there a universal color code for this?

I have the colors yellow, green, white, red and black.


texts: Can the current through a connector be higher than the rated current at lower voltages?

texts: I have been searching for power connectors for connecting the DC motors in my project. The motors are rated at 24v and 20A stall current. I find connectors with 5A current rating and 250V max. The motor's input power is 24*20=480W considering a single motor. A two pin connector with 5A and 250V has 1250W power. So can it be used to connect the motor? Will the connector handle that much current. Also, since this is my first time figuring out which connectors to use, please tell me the specifications other than voltage and current to consider while choosing the connector.


texts: Oscilloscope averaging and standard quantum limit

texts: Oscilloscopes give a Vrms noise and have a noise floor, but if I average for a long time to infinity, am I at the standard quantum limit and does SNR keep improving with the sqrt(N averages) forever?


texts: What is the difference between kernel and filter? (Not for CNN, in general)


texts: Replace crystal earpiece in bat detector circuit

texts:
I've been following the instructions on http://pw1.netcom.com/~t-rex/BatDetector.html which includes the following schematic for a Frequency Division Bat Detector circuit:

The instructions clearly state (http://home.earthlink.net/~bat-detector/SBD2Parts.html note #5) that a crystal earpiece should be used. However these are increasingly hard to come by.

Is it possible to use a non-crystal earphone with this circuit? Or is there any recommended modification to the circuit to enable it to drive a pair of earphones?


texts: MCP23017 to control a relay board failing when 6 or more relays are active

texts:
I'm having a problem with a circuit I'm building.

I have connected a MCP23017 to a Odroid C1 via I2C with a level converter. And the MCP23017 is connected to a 8 channel relay board.

The thing is that if I activate each channel independently it works just fine, I put a timer to set 1 on 1 on and off and it works.

But if I do the same thing without setting off the previous one, after a random time it start to turn on and off relays that are not correct, it's like the MCP23017 goes crazy, so if I restart the application it will work fine again until the same happens.

It's like when the relay board is consuming more power the MCP23017 goes crazy..
I tried putting a 47uF capacitor in the MCP23017 VDD-GND pins but it didn't fix it.

Any ideas in what can be causing the issue?

Thanks.

Edit:
@Mike I'm using this relay board:

This Odroid C1
This level converter to match de 3v3 I2C on the Odroid with the 5V on the MCP23017: Image in comments I cant attach anymore
I'm using an external power reguled to 5V by this: Image in comments I cant attach anymore

And of course the MCP23017.

I have connected the GPB pins of the MCP23017 to the pins in the Relay board.

Here is the PCB I built for this:
It has a lot of other components, but the one I'm trying to use now is the MCP23017-1, Relay-board 1, Level-Converter, DC-Regulator, and the Odroid connector.

The idea is to control multiples things with this. But I'm having trouble with the relay board in that way.

If the sequence is with one on one, it works without a glitch, if I start turning on a few at a time it goes crazy.

The relay board works with GND on the channels, so if I set the pin to 1 it turns off, if I set it to 0 it turns on.


texts: Driving a high-power LED at very low levels *efficiently*

texts:
So, I have these garden lights powered by solar cells. I also happen to have a power-LED over from a broken flashlight, I think its a Cree R2 or Q5 or similar. These lights charge a 1.5V 600mah Nimh battery during the day, and then light up these rectangular low-power leds.

Now I would want to experiment with simply driving a high-power LED at similar, or slightly lower power levels, meaning a very very low current. I have not measured the drive current for these, but I imagine its well below 50ma. The theory being that it will be brighter still because of the excellent efficiency of power LEDs in this power band.

I know power leds generally require current limiting or control, and that the battery voltage is not enough so I will need some sort of boost circuit if not already present.

What I am wondering is what is the most efficient way of doing this, without being overly complicated? Is it possible to do this with just a resistor, or am I still prone to current run-away at these low levels?


texts: In the circuit above, the sources of the two MOSFETS should be grounded to the same ground as the FET driver as shown in the schematic ?


texts:
I was shocked to see how cheap the chinese rice lights are! They even come with a controller attached with them, which allows you to change the lighting pattern.

I wanted to know what could they have used inside the controller box to make it cheap as well as functional at the same time. I opened the box and found nothing but few resistors, transistors, capacitor, diode, a push button and a "chip".

source: YouTube

I do not understand, what this chip may be and how's it controlling the lighting pattern. It doesn't have any transformer so I think this chip couldn't be a microcontroller. Then what could be this chip, that's powered by AC mains, and controlls as well as powers the light bulbs?


texts: Why are some IC's programmable in circuit, but others aren't?

texts:
Why are some IC's programmable while still connected in a system/circuit, but others aren't? What's the determining factor(s) for whether a chip can or cannot?

This question stems from my research on ICSP headers, and particularly, a statement made that "In most cases the MCU doesn’t even need to be removed from its circuit first [in order to be programmed via an ICSP header]."

Source

Edit: This is in relation to AVR ISP/ISCP.


texts: Why is -12v connected to GND in this schematic?

texts:
A couple of questions:

1) It looks to me that the three-prong ground connection in the bottom right of this schematic is the only ground connection. I used the GNDPWR symbol in my KiCad schematic to represent this ground connection. Can (or should?) this GNDPWR be connected to the "normal" GND which I am using on the jack sockets which connect to the inputs/outputs?

2) Why is the -12v connected directly to this GND? Is this just saying that the GND reference is -12v? But because I am using op-amps and a dual-rail powersupply, don't I also need a 0V GND? Won't it cause a short-circuit if I connected the -12v GND to the 0v GND? I do not understand.

3) Can I use any op-amp for U1-U4?

4) For the op-amps should I use a +/-15V power rails? Or should I use +/-12V?

5) What does the test point 4 mean (near the +12v)? Should I just ignore that?


texts: Is this an appropriate way to test a 7805?

texts:
Trying to check some 7805 voltage regulators. I do not have a DC power supply and do not want to test with the circuit hooked up to mains. That leaves me and my multi-meter.

http://www.androiderode.com/how-to-test-voltage-regulator-ic/

This seems reasonable to me, and both of my 7805s have failed step 4. Before I go out and buy two new ones I was hoping that I could get some confirmation of this method.

Thank you


texts: Why is a 103Z capacitor use with N20 DC motor?

texts: So capacitor 103z is used in parallel with N20 DC motor, I would like to know why?


texts: Find DC components of npn and pnp transistor

texts:
I'm sorry but I can't seem to figure this transistor question.
The question goes as follows:

Draw a DC-circuit and determine the unknown component values. Which DC-voltages  ( reference is ground) and DC-currents will be measured ?

simulate this circuit – Schematic created using CircuitLab

These are the values that  are given

I can't seem to start anything with this problem using only the values given. I would appreciate some help, this is no homework but if you find that I haven't done enough to try and answer he question, it is ok is you close this question. I just don't know how to find the components using only those given


texts: What are similarities between RTC DS1374 and RTC DS1307

texts:
I mostly work in software and not good in reading Hardware data sheets.

I need help in understanding the similarities between RTC DS1374 and RTC DS1307,From below link I could make out that both share the same address on I2C bus and have same set of registers but still few doubts would like to ask.

http://spellfoundry.com/arduino/ds1374-rtc-arduino-library-2/

1) Do both DS1307 and DS1374 have exactly same copy of register set?

2). Do both stores times as year-month-day-hours-minutes-seconds?

3). Do both have have their registers mapped to NVRAM of equal size?

How much DS1307 code can be reused on DS1374?

Any comment would be useful.

Thanks.


texts: LTspice - how to simulate real TTL gates?

texts:
I am trying to make simpler more general questions that might have more generally useful answers.
If you build a mixed analog digital circuit then you need to have models of real TTL or CMOS gates which have realistic current characteristics, sensing thresholds, etc.
I have an example with just two inverters:

and that second inverter doesn't reach 5 V output when the "load" R7 is 1 kOhm. But in real life I know that if I use a 1k resistor to ground I get fine near 5V potential on the output. So I know that somehow these parameters don't work right in LTspice.
Are there best practices how to set them?
Are there libraries of LTspice devices for common TTL and CMOS (74LS, 74HC...) devices to use in LTspice?
I know LTspice is for analog simulation, and that's the point.
If the answer is to draw up the schematics of the gates with transistors etc, as they are shown in the data-sheets, then that's a heck of a lot of work. Didn't somebody do these already? Google didn't show much.


texts: how to program the fuse bits of atmeta32u4 via the usb port?

texts: here I have an avr development board with a core of type Atmega32u4. I can only access to the memory via a usb cable.The default fuse bits seem to enable the JTAG which I want to disable. Unfortunately, the lock bits only allow me to program the application section. Does anyone know how to change the fuse bits via the usb port in this case?


texts: Voltage applied to secondary is not matching calculation

texts: Why is the RMS voltage applied to the secondary not 3.3 V in Multisim? 120/36 = 3.3 V


texts: Is forward biasing or reverse biasing an inherent property of a diode?

texts:
I read a tutorial about transistors and I reached the following sentence.
"The Bipolar Junction Transistor (BJT) is a three layer device constructed form two semiconductor diode junctions joined together, one forward biased and one reverse biased."

It made me think that diodes are inherently forward biased or reverse biased but from what I know this depends on what is the direction of the voltage applied to the diode, so the same diode can be forward biased or can be reverse biased depending on the direction of the electric field (voltage).

Is this right?


texts: How to control three LEDs with two uC pins using just passive components?

texts: I only have 2 (3-state) pins available on a microcontroller and need to control 3 red LEDs, uC is running on 5V. I can only use passive components in addition.


texts:
Screen shot of the question  is given below.

What I know

B field acting on the Ferris wheel is given below,

And induced E.M.F initially is zero , therefore I can neglect answer number one and two.

But how to proceed further. I am simply stuck .


texts:
I'm working on RF Module(433MHz ) for Communication between Robot and controller. So I want to test this first.

Here is the thing
I've used two Encoders Named HT12E and HT12D which are WORKING Fine when they are tested individually.

Now I Connected These to RF Tx and Rx, which on observation HT12E gave 1.54v(Constantly) to TX(Even while testing HT12E  gave same voltage, decoded successfully), 1.87-2v from data pin of Rx.

But I'm HT12D doesn't decode data here. This is my problem. Its so frustating for me to try for so many times and no output at all.

RF Module::
 http://www.engineersgarage.com/electronic-components/rf-module-transmitter-receiver

Sites Used::
http://www.technoburst.net/2011/07/rf-module-interfacing-circuit-example.html

(Source)


texts: I don't understand current source, voltage source, infinite resistance, zero resistance etc

texts:
When I google things like voltage source and current source they talk about things like maintaining a particular level, having infinite output resistance, or zero output resistance, etc. I don't understand what this means at all or why it must necessarily follow, and none of the online explanations actually get into why these things are the case. If something has infinite resistance wouldn't nothing happen because everything is blocked?
I also don't understand what an "open circuit" really means (to my eye it just looks like a broken circuit that isn't going to do anything). It's all quite horribly confusing to me and all the online guides and answers just repeat the same stuff. Can anyone explain this to me like I am a dummy?


texts: Calculating current in an unknown transformer with multiple isolated secondaries

texts:
I have an old power transformer that I'm retrofitting into a new valve amplifier. Having measured the voltages on the secondaries when 230V is applied to the primary and got the following results:

P: 230 V
S1: 356.2 V
S2: 34.56 V
S3: 6.453 V

The turns ratio of each winding is therefore:

S1: 356.2 / 230 =  1.549
 S2: 34.56 / 230 = 0.150
 S3: 6.453 / 230 = 0.028

The current flowing in primary at 230V was 0.07A. Using the turns ratio I we can calculate the current flow in each secondary:

S1: 0.07 * 1.549 = 45 mA
 S2: 0.07 * 0.150 = 460 mA
 S3: 0.07 * 0.028 = 2.495 A

This seems correct at first, but using these figures the combined power output of the secondaries would be three times that of the primary which is obviously incorrect as Vp * Vp = Vs * Is.

Two of the questions to this answer suggest that we can calculate the VA value as V^2 / R, sum the three VA values and then us the result to calculate how the VA of the primary is distributed between the secondaries. In this case the resistance would be DC resistance of the primary multiplied by the square of the turns ratio, plus the DC resistance of the secondary.

The measured DC resistance of each winding is:

P: 7.5 R
 S1: 28.60 R
 S2: 3.10 R
 S3: 0.10 R

Therefore the total resistance on each secondary is:

S1: ( 7.5 * (1.549 ^ 2) ) + 28.60 = 46.59 R
S2: ( 7.5 * (1.150 ^ 2) ) + 3.10 = 3.27 R
S3: ( 7.5 * (0.028 ^ 2) ) + 0.10 = 0.11 R

Therefore the VA rating of each winding is

S1: ( 356.2 ^ 2 ) / 46.69 = 2723
S2: ( 34.56 ^ 2 ) / 3.27 = 365
S3: ( 6.453 ^ 2 ) / 0.11 = 393

Therefore the total VA rating is 3482 and the power distribution between each secondary is:

2723 / 3482 = 78.2%
 365 / 3482 = 10.5%
 393 / 3482 = 11.3%

So now we can revise the current values we calculated earlier:

S1 = ( 0.07 * 0.782) * 1.549 = 0.035 A
 S2 = ( 0.07 * 0.105) * 0.150 = 0.049 A
 S3 = ( 0.07 * 0.113) * 0.028 = 0.282 A

This balances the power on each side of the transistor however it doesn't really correlate to reality. The third winding is for the valve heaters and given that his amp contains 4x 12AX7 and 4x EL34 the current required is going to be around 5.4 A however that's clearly not the case. The first secondary should also be much higher, in the range of 500 mA.

Where have I gone wrong? Is my original current measurement on the primary wrong? Do I need to be considering the load into which each secondary will be delivering the current?

Thanks for any help.


texts: Macroscopic physical significance of Thermal Voltage in Diodes

texts:
Everywhere I search, the thermal voltage in diodes is described either as

the microscopic property related to the average energy of electrons due to thermal motion
The constant in the ideal diode equation.

Now, I'd like to know the macroscopic significance of the thermal voltage. For example, something like it being the voltage across the diode in comparison to a diode a 0k if it were true.

It being a constant in the ideal diode equation is not so satisfying; I plotted typical values in the equation (https://www.desmos.com/calculator/fiwyqzw5ci ). There appears to be no discernible feature at is at the thermal voltage (black line), whereas the turn on voltage of 0.7 is a readily visible feature (blue line).

So, what is the measurable macroscopic significance of Vt thermal voltage?


texts: Difference between monthly, daily and hourly solar radiation

texts: I am currently modeling a solar tracker in MATLAB. But I am confuse about solar irradiance. Actually what is the difference between monthly, daily and hourly solar radiation? Which one is more accurate to test out the tracker? I mean my project is only to test the efficiency. It won't last for a very long time to do the observation.


texts: We have a piece of data acquisition equipment (voltage data logger) that connects to a PC via a USB cable for power and communication. Because of some other equipment we already own, it would be convenient to have this connected to a serial port using RS232 protocol. Is there any easy way to do this (e.g. an off the shelf product)? I have found numerous USB to RS232 converters, but they seem to go in the opposite direction. Can I simply use one of these cables and splice in to provide external power to the unit?


texts:
I have a simple digital invert circuit using ASAP7 nmos and pmos transistors. When I use Synopsys HSPICE to simulate the below script, it throws an error Definition of model/subckt "nmos_rvt" is not found for the element "xinv1^xm1". Please specify a defined model/subckt name.
However, when I change xm0 to mm0 (and xm1 to mm1) everything works! What is wrong with using xm0 as the instance name? Where is this documented?
The script:
** Generated for: hspiceD
** Generated on: Feb  2 16:49:44 2021
** Design library name: demo
** Design cell name: invtest
** Design view name: schematic
.GLOBAL vdd!

.TEMP 25.0
.OPTION
+    ARTIST=2
+    INGOLD=2
+    PARHIER=LOCAL
+    PSF=2
.INCLUDE "7nm_TT.pm"

** Library name: asap7ssc7p5t
** Cell name: INVx1_ASAP7_75t_R
** View name: schematic
.subckt INVx1_ASAP7_75t_R a y vdd vss
xm1 y a vss vss nmos_rvt w=81e-9 l=20e-9 nfin=3
xm0 y a vdd vdd pmos_rvt w=81e-9 l=20e-9 nfin=3
.ends INVx1_ASAP7_75t_R
** End of subcircuit definition.

** Library name: demo
** Cell name: invtest
** View name: schematic
xinv1 in1 out1 vdd! 0 INVx1_ASAP7_75t_R
v0 vdd! 0 DC=700e-3
c0 out1 0 2e-15
VIN in1 0 0 pulse 0 0.7 0 50p 50p 2n 4n
.tran 10p 10n
.END

```