texts:
Given multiple sheets in DipTrace, I am looking to do something like this:

There are a few ways I've found by which I can do something functionally similar - if not identical, - but which are visually awkward, take more room, are slightly misleading, harder to follow, and/or just plain don't follow the convention I'm used to.  The following illustrates those:

Is there some way to have something roughly similar to my first illustration above, preferably without some painstaking per-instance effort?


texts:
I found an old car DVD player, figured I might try and use the LCDs for something else, most likely with a raspberry pi. They're 4.5" displays, Prime View Model #PW045XS2. I'm thinking adding an RCA connector to the driver would be the easiest feat, the thing I'm not so confident on is the power.
I found the specs for the DVD player as a whole here: http://www.diagramasde.com/diagramas/otros2/PVS1950D[1].pdf Page 16 has the monitor diagram.

I want to confirm one thing - If I just connect an RCA port to the VIDEO/VGND pins, should that work or is there something else I need to do?

And I want to ask another - What kind of power supply do I need to connect? I'm fairly sure it needs 5V, but not sure on the amperage.
I did try a 5V 500mA supply (what I had lying around) and was able to get at least some of the backlight on.


texts: Solar panel charging battery loss over night from leakage current

texts: I am setting up a solar panel to charge a 12 VDC lead/acid battery to run a trolling motor for my dinghy. Does anyone have an idea as to how much leakage current there is through a 12VDC 8.5W panel when dark? Thank you.


texts:
I have the above code segment. I am a bit confused, so can one help me ?

 wait until rising_edge ( clk ) ;
      sig_a <= sig_x and sig_y ;
      sig_b <= sig_a ;

Does sig_b use new value of sig_a ?


texts: PCB Layout Help (with schematics!) - Split ground plane or not?

texts:
Obligatory "not an EE, just a ChemE trying to make some pressure readings for science"!

Schematic attached, along with my current layout. It's a 6-channel pressure sensor using MPX4115AP sensors and an AD7606-6 simultaneous sampling ADC. The ADC is overkill, probably, but I happen to have about a dozen laying around. It communicates to the host via SPI.

Each pressure sensor has bypass caps and an RC filter on the output to remove any fluctuations that occur due to high-frequency pressure disturbances in my system.

The whole board is powered by a single LM-1117 5V regulator in an SOT-223-4 package. The upper-left corner of the board acts as a heat sink. With the exception of the two pours in the upper-left (+5V and the regulator input capacitor), all the other pours on the top layer are ground. The entire back layer is +5V.

I've been reading a lot about how to properly lay out a ground plane to separate analog and digital portions of an ADC system. This design uses a star ground point at pins 2 and 3 of the ADC. The ground plane under the ADC itself goes off and runs under all the sensors, while the ground plane under J2 and all the digital pins is split off, only tied together at the star ground point.

I have a few questions. Am I overthinking this? Do I really need to separate the ground planes when everything runs off a single supply? I'm already using maximum oversampling on the ADC since I have plenty of time to take measurements (around once per second, later averaged to a 5-second reading). The measurements don't need to be ultra precise, either.

If separate ground planes are recommended, should I separate the power plane as well? I've read that one uses separate ground planes when the analog and digital circuitry are operated from different supplies, but I'm not doing that, hence my 1st question about split ground planes.


texts: How much does a 3000 watt down transformer consume when not used?  In NZ and use my usa clothes washer. Should I TURN IT OFF when not used?


texts: Changing bootloader fuses - Arduino based ATmega32U4

texts:
I'd like to develop an Arduino board with the ATmega32U4 MCU but in a low power mode. I've been searching and I know I have to change the fuses to prevent the brown-out-reset (BOR) when the battery is lower than a certain voltage. I'd also have to change the CLK bits to divide the 16MHz crystal into a lower frequency mode to consume less energy.

I found this webpage to change the fuses.

I just don't know how to do this (which program to use - FLIP?? and how to proceed) and if by doing this bootloader change the board would still be recognized in the Arduino 1.0 program (boards sections - like a Leonardo variant 8MHz for example). I have the 6x2 ISP pins accessible.

By the way, I have a board with the ATmega32U4 and it's 0.1uF capacitors and a 16MHz crystal (+ 2x 22pF caps). I also have the ATMEL mkII programmer with the ISP 3x2 MISO/MOSI/CLK/RESET/VCC/GND connector.

Would somebody know how to help me?


texts:
What would be the best way for me to boost 3.7V to 12V with 300ma max draw?

I've been looking at this: LT1303 and this MC34063A.

I actually bought an lt1303 last week but I couldn't get anymore than 20mA from it, if I try to draw more, the avg voltage goes down, ~10v at 70mA (hadn't got the chance to hook it up to a scope yet). It looks like the lt1303 limits current draw from my battery to about 200mA.

Now, after digging around digikey a bit, I found the other part, MC34063A and it looks like it can do better. I say that only because it is has this "Current Output Rating" of 1.5A, and I don't completely understand what it means. Do you think I can at least get 100mA 12V from a 3.7V source if I use this and then just wire 3 in parallel so I can do 300mA. Thoughts?

Update: Here's a schematic that's close to what I have. just ignore the extra parts and replace L1 with a 15uH (also tried 30/45uH) and R4 with a 100K. It outputs ~13.6V with no load.


texts:
I want to build a tiny obstacle avoiding robot using a 3v coreless DC motor. I've been using L293D to control 5V motors and up, but I can't seem to find a motor controller that works with motors below 5V anywhere. I also have 3V Canon two-step motors, but I would much rather use the 3v coreless DC motor if possible:

Do such a small motor-controllers exist or do I need to looking for a different solution? All I'm trying to do is have some kind of tiny component that will let me control both (or at least one) of the motors in both directions.

Normally I could use L293D, but it requires 5V inputs for the trigger pins as well, but my project will be using only 3.7v.

Thank you!


texts:
I want to know what is the difference between sample method and sample and hold method ,and why are these two methods important to study analog to digital conversion and its reconstruction back to analog signal,
and what is the effect of different sampling frequencies on the reconstructed signal.


texts: Keep brightness high whilst multiplexing [SOLVED]

texts: I have searched a little but I'm a noob to electronics so it was hard for me to understand. So here is my problem. I have made a little 3 x 3 led matrix to test. When powering 1 led it was fine, but when I tried 3 at once, they were all dim. Should I be using a 100 ohm resistor instead of 220? Please give a simple and detailed response. Like I said, I'm new to all of this. (keep in mind this is just a test. I wouldnt actually use multiplexing to power 9 leds.)


texts: Decimal conversion of a 32-bit hexadecimal number

texts:
Im working on this question:

Consider a 32-bit hexadecimal number stored in memory as 1B08C22B. If the
number is an IEEE single-precision floating point value, determine the decimal
equivalent of the number (you may leave your answer in scientic notation form,
as a number times a power of two).

And I have managed to get the following answer is it correct?


texts: Removing optimization changes I2C timing

texts:
I'm at using SAM E54 Xplained Pro  to get temperature readings from a MCP9600 hooked up to a thermocouple over an I2C bus. I'm using Atmel Studio 7 with I2C drivers generated with Atmel Start. I'm using a Saleae logic analyzer to help debug.
The temperature read works fine using an optimization level of -O1, but when optimization is changed to -O0, the I2C timing is changed, resulting in faulty temperature reads.
Here is a temperature read with -O1 optimization level:

As you can see the temperature is read as 0x016B which corresponds to about 73 degrees F.
Here is a temperature read with -O0 optimization level:

The temperature is read as 0x0101, which is incorrect.
Can anyone offer insight into why removing optimization changes things, and how I can make the code work with optimization level -O0? Any help is greatly appreciated.
Here is the code:
#include "driver_init.h"

#define MCP9600_I2C_ADDR 0x60

int main(void)
{

    struct io_descriptor *I2C_0_io;
    uint8_t th_register = 0x00; //register that holds temperature measurement
    uint8_t temp[2];

    i2c_m_sync_get_io_descriptor(&I2C_0, &I2C_0_io);
    i2c_m_sync_enable(&I2C_0);
    i2c_m_sync_set_slaveaddr(&I2C_0, MCP9600_I2C_ADDR, I2C_M_SEVEN);

    io_write(I2C_0_io, &th_register, 1);
    io_read(I2C_0_io, &temp[0], 2);

    while (1) {
    }
}


texts:
I'm confused with the definition of phase noise. I'm referring to this IEEE document.
A noisy oscillator output is \$v(t) = A\sin(\omega t + \phi)\$, where phi is random phase deviation. I assumed no amplitude noise.  So carrier power is \$ P = \frac{A^2}{2*R_L}\$.

I can find the \$\phi\$, in radians and compute its onesided power spectral density with periodogram in matlab. Thus, I have \$S_\phi\$ in rad\$^2\$/hz.

Now, the IEEE document says, phase noise is defined as one half of \$S_\phi\$, but also says its unit is dbc/hz. Should not we dividing \$S_\phi\$ with P to get dbc/hz, but then \$S_\phi\$ unit is rad\$^2\$/hz not power, i.e. P is in Watts?

How can I correctly compute single side band phase noise spectrum in dbc/hz from \$S_\phi\$ which is in rad\$^2\$/hz?

Edit: the document I posted is old (1999). This is the active one. But still, my understanding seems to be correct.


texts: How to transform an AC signal of wide voltage to pulses

texts:
I want to build a device that measures frequency of possibly different electrical alternators, not having much control of their parameters. For this I need to get digital pulses out of the AC signal from the alternator.

The only information I have, is that voltage from the alternator can vary from few V to 100 V, depending on their rotational speed. Frequency under the kHz.

The power usage of such circuit should be the small (<0.1W).

Output should be a digital signal of a fixed voltage. It's totally acceptable (and actually useful) to ignore signals below or close the high level of the digital signal (say 3.3 V).

How to get such pulsed output from the AC input, in a safe and fairly efficient way?

To make the question more generally useful, feel free to add more cases (smaller/higher voltages, higher frequencies).


texts: How Would a CPU Improve if its Logic Circuits were Reduced?

texts: Is there an estimate as to how a common CPU (for example, Intel i7) would improve if all of its logic circuits were reduced  to their theoretical minimum, in the sense explained here? By "improve" I mean in metrics such as: size, number of transistors, power consumption, speed.


texts: Analog input scaling before ADC sampling

texts:
I'm trying to read a voltage value from a chemical sensor. the sensor value can range from 0 to 7 volts. My microcontroller is running on 3.3V. I'm not allowed to consume current from the sensor so I used the following circuit to amplify the current.

But this circuit is not acting like what I've learned in theory.

When the input terminal is left unconnected the output voltage is about 3V.
When the input voltage is below 0.8V the output is also 3V but when the input voltage goes higher than 0.8V the input falls to 0.300V.
The transfer function of the input to output is not linear!

What is the best practice to solve this problem?


texts: Voltage regulator circuit, efficient, low necessary drop

texts:
I want to get a 4v supply from >=5v. (I.e. as little as 1v drop)

The load current will vary by a factor of 10,000. (From 5uA to 50mA).

I need the circuit to be really efficient when there's a small load.

I wanted a darlington pair set up as emitter-follower following a zener diode regulator. The problem being fairly obvious, the 1.4v drop exceeds the 1v I have available, so it's not usable.

Instead, using a single NPN follower following a ZD in isolation would give an hfe of about 500 say, meaning the current taken by the ZD with the supply at 5v would have to be 20 times greater than the load is using in standby, in order for it to be able to supply the load's peak current! And significantly greater when the supply is say 8v, the current taken through the ZD would be 200 times the load's standby current!

Is there a better way?


texts:
let's consider this circuit:

How can I analyze it? Which is the expression of the current in the short circuit? Is it correct to split the circuit in the following way (I always did it when there was a short circuit, but I do not know if it works with current sources):


texts:
I'm looking to build a little pcb that boots my main PC over wifi with a ESP32. Because yes, no wake on lan or other fancy methods available.
Looking through motherboard specs, I couldn't find a maximum amperage supported for front panel pin header. Is there any standard for them?
The board itself will only have the esp32 and a transistor to act as a button. And a push button, of course, to power the thing on manually when required.
1amp should be enough. So my question is.
Could I power the board from the sw_pwr pin without problems?
As far as I understand, that pin is always giving 5v and I would prefer to not fiddle with psu wires, I think the best approach is to just use the sw_pwr header.


texts:
I am trying to build a fork sensor. While I am OK at electronics stuff, for the first time in my life I took active role in making a finished product. Looking at our competitors designs, I noticed a part which helps keeping the 3 mm LED and photodiode fixed on the case:

The part also has a glass (or plastic?) part on the aperture, protecting it.

What I wonder is if it is a commercial product, that is readily available to buy, or is it specially manufactured? The most related thing to this is called "LED bezel", but this is not exactly what I am looking for.


texts: TIVA TM4C123G check clock frequency with oscilloscope

texts:
I'm trying to configure system clock in the TIVA TM4C123g board. I'm aware that this clock signal goes to a pin called OSC0 which, according to this, is the pin number 41 (see page 22). According to the same document, that pin is supposed to be in the PCB's U1 module, which can be found in Component Locations.

I have found the module in my board:

.

However, there are no debug pins connected to it. Am I supposed to measure directly the pins that come out from the chip? Isn't it dangerous? (you could touch two of them with the probe, causing a short).

How can I measure the system clock frequency so I can be sure I have configured it correctly?


texts: Problem with adding unmodeled dynamics to a system

texts:
I am trying to do an analysis similar to : Stability‐and performance‐robustness tradeoffs: MIMO mixed‐µ vs complex‐µ design

I have a MIMO system composed by a mass-spring damper system which has a plant with \$6\$ inputs and \$4\$ outputs.

In the system is present an unmodeled dynamics on the acutators, and it is modeled as a delay, and it adds to the system as a multiplicative uncertainty.

To add the unmodeled dynamics to the system, I am trying to do the following:

G = ss(A,[B1 B2],[C1;C2],[D11 D12;D21 D22]);

delta = ultidyn('delta',[2 2],'SampleStateDim',5,'Bound',1);

W_tau = ((2.1*s)/(s+40))*eye(2);

G  = G*append(eye(2)+W_tau*delta,3)

where G is the plant of the system, and contains uncertain parameters.

If I do this, I get the following error:

Error using  *  (line 80)
Model I/O dimensions must agree.

To try to solve the problem I am try to look at this : Control of a Spring-Mass-Damper System Using Mixed-Mu Synthesis from the Matlab documentation.

I have also found that the problem does not exists if I consider a \$1x1\$ system, so if I do:

G = ss(A,[B1 B2],[C1;C2],[D11 D12;D21 D22]);

delta = ultidyn('delta',[1 1],'SampleStateDim',5,'Bound',1);

W_tau = ((2.1*s)/(s+40))

G  = G*append(1+W_tau*delta)

everything works fine.

I have also tried to do:

G  = G.*append(1+W_tau*delta)

but still does not work.

can somebody please help me solve this problem?


texts: Power microcontroller from super capacitor

texts:
I have a uC that works with 1.8V up to 3.3V. Current consumption is at about 20uA in sleep mode and about 12 mA in active state. The uC will enter active state for about 100 ms every minute.

So I am trying to power this from a Vishay super cap: 15F at 2.8 volts with an ESR of 1.2O at 1kHz.

Math says I can pull about 4.10 mA from this cap before its voltage drops to 1.8 volts, at which point the micro will shut down.

So.. the question: am I missing something? Should I add a small electrolytic between the super cap and the micro? A small zener to limit eventual (possible?) spikes in voltage? Should I add a buck boost converter to get a bit more out of the capacitor?

Also.. if I disable brownout detection on the microcontroller, maybe I can pull something like 10% more charge from the capacitor? I can implement error checking in case the micro outputs gibberish, which usually happens in low voltage scenarios with brownout detection disabled.


texts: Why bridge the GND wire on a DE-9 connector?

texts:
Why would someone want to bridge the GND wire to the metal shield of a DE-9 connector? Take a look at the picture below.

A 10 position flat ribbon cable is soldered to a DE-9 connector (male). On position 5 (GND) a short piece of wire is soldered, which branches off and is soldered on the metal shield/housing of the connector.

Why would you want to do that?

On the other side of the ribbon cable is a 10+10 IDC socket that connects to the COM port header of a PC motherboard.


texts: How important is "mm pitch" for a capacitor?

texts:
I want to repair my boiler, so I found this howto.

He writes I need a MKP X2, 26.5 x 10 x 19 mm, 0.47 µF 275 V/AC ±10%, 22.5 mm pitch.

The closet one I can find in my country is this one that doesn't mention 22.5 mm pitch.

Question

What is mm pitch and is it important for my usage?


texts: Why does a 1.8mA current draw still create a blue glow in my Nixie Tubes?

texts:
I've created a Nixie Clock with 6 IN-14 Nixie tubes. I've run into the issue where the tubes have a faint blue glow surrounding the digits. I've heard this is due to the Nixie tubes being over-amped and may need a higher current limiting resistance.

So I went ahead and measured the supply voltage, current limiting resistances, and the voltage drop across the current limiting resistors. The tubes are supplied with 160V. The current limiting resistances range between 21.8k and 21.6k. I've also measured the voltage drop across each of these resistors to range between 40.0V and 35.7V. Just by taking the smallest resistance of the lot and pairing it with the highest voltage drop I'd arrive at a max current draw of 40.0V / 21.6k = 1.85mA. Some quick searches online tell me the highest possible current through an IN-14 should be 2.5mA, and the typical current draw of an IN-14 Nixie tube is 1.7mA. Should I go with a higher resistance just to be safe, or is this behavior normal for some nixie tubes?


texts:
Is there a limit on the number of GPIO that can be set to INPUT_PULLUP at the same time?
My project is based on an ESP32 Devkit board. I've enabled the internal pullup resistor on 7-8 GPIOs. Each one is connected to ground via a switch. Wires are 5-10m long:
gpio
  |
switch
  |
 Gnd

Most GPIOs are ok. But a few of them (gpio5,16,17) does not delivers 3.3V. I get values like 2.1V which is not enough to read a HIGH state on the gpio.
The board is powered via the USB port. It also powers a 8 relays board.
Thanks.


texts: How to make a solar battery charger using more than 1 Lithium polymer

texts:
I have atleast 5 lithium polymer [not 18650] batteries taken from laptop. the print on them is pale, it is 14.01wh [ 6 cell 6 x 14 = 84wh, but i split each battery now]
it is 3840mah each.
I would like to - how to recharge them using solar panel [ say 10WH 12volt]. 3 batteries should give me 12v. so I think I can use 3 of them . but dont know, what modules to use.
solar panel - has 8A controller.  please suggest modules to be used.
purpose: I want to use that to power a 12v motor driver.
thanks
EDIT: Added pic for understanding.
Goal - create battery as in pic.

Example:

P.S. I am aware of fire hazard. So looking for sensible answers. Thank you


texts: Current coming out of the 5V source would never be 0 so what would make the current coming out of the 3v dependent source 0?


texts: What are the D02, D08, D10 arduino pins equivalent on Teensy?

texts:
I have a WebUrban Wifi chip which is compatible with the original AsyncLabs WiShield library. I am wondering what I need to do to hook up this chip to a Teensy. I've figured out all of the pins I need except for the ones that plug in to D02, D08, and D10 on an Arduino.
How do I determine which Teensy pins are equivalent to those?


texts: old 80C31 circuit not working. EPROM data retention issue?

texts:
I have an old piece of pro-audio gear in for repair. It dates from 1990. It was a fairly high-end piece of gear at the time and still has some value so it is worth repairing. But the symptoms I see have me scratching my head.

At some point, the front panel just stopped working. The old fluorescent display is perfect, but no switches work. I have schematics and service info for the main unit, but not the front panel, so I traced the circuit.

I discovered that the 80c31 processor reads the switch matrix but writing 0's where it needs to write 1's, so the switches always read as not pressed. I can see this quite clearly with the scope; there is an octal latch (U28), it is clocked, but the input I looked at (pin 13) is always 0 at rising edge of clock. (It isn't stuck low, and it comes right from port 0 of the 80C31.)

The 80C31 seems to run fine. In fact if I ground a node in the switch matrix (cathode of the diode CR4), the associated switches work. So the scan is working, the switch value gets reported back to the main CPU, and the display works.

The issue is just that the 80C51 doesn't activate the latch to read the switch.

I am really scratching my head here. There doesn't seem to be any hardware issue, the processor is just not trying to read the hardware when it should. Why did it suddenly stop working? It is as there is a software config issue, but nothing changed to cause that, as far as I know. (The owner did buy some upgrade ROM's, we have the same issues with either set.)

What could do this? I am clutching at straws a bit here, but now I am wondering if the EPROM (it is windowed) has started to lose data after 20+ years. (It has a sticker and it would be dark in the box, but 28 years is long.) For that I would expect a total crash or random behaviour, but I guess that losing just a bit here and there might also happen - never really experienced that kind of thing, so I don't know.

Anyway I am considering getting hold of an EPROM reader and running the image through a simulator to see what it does.

Any other ideas?


texts:
Below is a diagram I created in preparation for a project I am working on to add additional lights to my vehicle. During my research, I found that it would be best to add a relay box to the engine compartment to keep the high current out of the cabin. From there, I looked at the power needed from the lights I will be installing. Each light cube (there are 4) operates on 10V-30V (obviously I will be using 12v) and contains (8) 3W LEDs. With that in mind, I spec'ed the circuit for 100W @ 12V and with the 1.3x margin for cold power-on I settled on a 10A fuse. Given that I will only need a maximum of around 8 feet of "high amperage" wire, and the 10A fuse, I decided to use 14 Ga wire. The switching circuit will use 22 Ga wire as the requirements are small. The switch will tap a fuse slot that is currently not used for ignition keying. Additionally, the switch has an LED that is not pictured in the diagram. A supplemental diagram from the switch manufacturer is provided below. The switch will be wired on pins 3 and 5.
What I am unsure of here, is the use of the 40A auto relay. I don't do much with relays or auto circuitry and looked for smaller relay sizes but they don't seem very common in the auto world. However, the 40A seems excessive. Will this create any problems? Additionally, is there any component here that I am overlooking/not considering?
Switch: Link to Diagram
Diagram:


texts: Adapting an HF attenuator to higher power

texts:
I want to make a 25W HF amplifier that can handle an input up to 8W. I found a schematic by ON6MU which can handle up to 2.5W input. There is an attenuator at the input that I copy here. R3-4 is 1W, R2 and R5 are both 0.5W.

What would be needed to change this circuit to allow for an up to 8W input? Would it be enough to take an R3-4 that can handle 5W and R2 and R5 that can handle 2W, or would I need to change values as well?

How would I actually calculate this?

The attenuator should work for 17m - 80m bands.

simulate this circuit – Schematic created using CircuitLab

The full schematic, for reference purposes:


texts: Is it possible to design a 4-pin to 24-pin atx molex converter?

texts:
first of all I am a real novice in electronics but according to my circuits and electronic classes I think this should be possible:

I want to use a 4-pin ATX cable as a power input in order to generate 24 outputs. Basically, my idea consists in using zener diodes.

Having 12Volts as input and then a 5Volts zener diode I should be able to have a +5V output, then connecting this output to a 3.3Volts zener diode I should be able to have a +3.3V output.

Here's a circuit I've barely drawn:

My question is how would I deal with the -12V output? And also once all voltages are tested and wrapped in the 24-pin connector, How safe would be connecting a motherboard to this result?


texts: How to compute DC offset of analog circuit?

texts:
I have an analog circuit which has an input voltage range Vin of 5V - 10V and output voltage Vout.

One can assume that the circuit has been simulated and a DC sweep of Vin with a range from -10V to +10V has been performed and the corresponding Vout=f(Vin) has been plotted.

Is it correct in that case to compute the DC offset of the circuit just by obtaining Vout at Vin=0V even though this is outside of the allowed input voltage range?


texts: LM2596S-ADJ Buck Converter Circuit heating up and wasting a lot of voltage somewhere

texts:
I've built my own DIY adjustable buck converter using a teensy, a gate driver and all manner of components. It worked ok (I was able to vary voltage from 20 mV all the way up to about 20 V when my input power was 24 V) but I had an overheating problem. I assumed my calculations of the components were off or my wiring was crap. I'm very new to this power electronics business. So I decided to literally follow a set out circuit:

https://prnt.sc/stnwx5

At PSU = 24 V, the max voltage I can get on the load is only about 12.5 V and the current shown by the PSU is about 0.850 A. Meanwhile, the LM2596S begins burning hot.

At PSU = 15 V, the max voltage I can get across the load is 12.69 V and the current shown by the PSU is about 1.285 A. The LM2596S isn't getting hot, just warm..

What is going on here? The PSU I'm using is: https://uk.farnell.com/tenma/72-10495/power-supply-2ch-30v-5a-adjustable/dp/2251947

Is it my diode? Or is it my load? Or is it the fact that I'm using long wires from my PSU (IN) and long wires to my physical load (OUT)? Everything else on the circuit is soldered as closely as possible:

https://prnt.sc/stobxv

So why can I not vary the voltage on my load nearer to 24 V if I set the PSU at 24 V? Why is my LM still getting so hot in that setup? I literally followed a schematic and instructions that said I should be able to vary my power from 1.2 V - 40 V depending on the PSU power. But if I put it at 24 V, literally 12 V is lost somewhere and my LM starts burning up and producing a chemical smell.

What is wrong now, can anyone advise me?


texts: Why is a diode-connected BJT more "ideal" than a simple pn diode?

texts:
I have often seen it stated and discussed that a diode-connected BJT has an ideality factor (n) closer to 1 in Shockley's diode equation when compared with a simple pn diode's ~2/3.

Why is this?


texts: RS485 transmission line high voltage protection

texts: I have a reuirement to protect RS485 transmission lines from up to 500v which may be prolonged. Basically I have 485 data within the same cable as 500v, and the cable is under water, so sometimes if a fault occurs, not only do i need to rectify the fault, but I always need to replace the RS485 transceivers at either or both ends. space is limited so I can not fit in adams units with this built in, I am down to chips and components, but I can't opto isolate like I can with 232 because 485 is a loop as opposed to an individual line for tX and RX. Has anyone got a good idea for me, ideally a chip that can be plug in would be best for speed and ease of replacement if they fail.


texts: Need a solution for a multiple switch circuit

texts:
I must preface this with I am not an electrician. Just a hobbyist. I have a unique problem I am trying to solve. With the Covid situation our curling club needs a solution for their double takeout board. Currently its a sandwich board that is passed from sheet to sheet when someone completes a double takeout.
My idea is to have a foot switch at the end of every sheet that would control either a light above that sheet, or a scoreboard(type device) that would display the sheet that has last pressed the foot switch. The catch is only one switch will have priority and remove the light/scoreboard from the other sheets. ie. only one light can be illuminated or one sheet indicated on the scoreboard.
I started mocking this up at home with wall switches and soon realized the amount of wire there would be running back and forth.
Is there a pre-existing solution or a diagram of how to accomplish something like this that someone could point me to?


texts: Troubleshooting fried FPV receiver hooked up to SPDT switch

texts:
I want to be able to charge a FPV Receiver (specs) via a phone and charge the phone with a battery. I tried using a single pole double throw switch without the power source connected to the phone first. So essentially it was a ON/OFF switch for the receiver to receive 5V from the phone. This worked the first time, but when I tried it again the receiver didn't work. I can't imagine how my setup is different from connecting and disconnecting the micro-usb to the receiver (its intended use). I took care not to short any of the wires.

Here is my wiring. The power wire from the phone (red) goes to the middle terminal and the power  wire for the device goes to the right terminal from respective micro usbs. Everything else is connected (data + , data -, ground). Is there anything wrong that could have screwed up the receiver ?

The receiver is connected to phone. I eventually want to add a power source for the phone to the switch.

The schematic below includes the power source, which I did not connect to the switch for my failed test.


texts: Ground loop between Pc and projector via VGA cable

texts:
Our hall has a projector hooked up to a PC via a VGA cable but we're seeing horizontal bars on the projector image when we turn on the lights in the hall.
I'm think it's a ground loop problem. I'm trying to eliminate ground loop between PC and projector via a VGA cable. I've tried hooking them to the same power socket which didn't eliminate the horizontal bars on the projector image.
I disconnected the safety ground inside the projector plug and the horizontal bars on the image went away, but I believe this is not a long term safe option. but does seem to indicate that the ground loop is the cause of the horizontal flicker/bars.
Is it possible to disconnect the ground signals inside the VGA cable to eliminate the ground loop without making it unsafe/losing the picture entirely? (pins 5-8, pin 10?) What would be the consequences of doing so?
I don't want to degrade my image quality, or risk damage. I'm also not super keen to "experiment"if I might damage something, and also re-soldering the vga cables is fiddly work.


texts: I have seen this datasheet of high current DC motor Driver. Its mentioned that it can be used to drive the motor in forward or reverse direction. I puzzled by seeing only 2 X IR7843 MOSFET's are being used can any one help me to understand how it works.


texts: How to block reverse current from battery to charger (DC-buck CC/CV module)?

texts:
The set-up

For a project, I have a set-up where the power to the main load comes from either a AC-DC adapter input (24V) or a battery pack (12V to 16.8V - 4S4P 18650 Li-ion cells). The battery pack is connected through a BMS module.

Both power supplies are connected to a switching circuit that 'selects' the right source to use (DC if available, battery otherwise), using the LTC4416-1 chip.

The DC input is also connected to a charging circuit using a DC-DC buck converter with CC/CV limiting to the BMS/battery pack.

The problem

For safety, I want to put a reverse current blocking protection between the buck module and the BMS/battery. (To prevent current from flowing back if the DC plug is pulled and thus the buck has no power.)

I've read/seen a lot of posts/articles/datasheets/instruction videos/etc about possible options, but can't seem to find the right solution for my situation (supporting charging current that starts @ 4.08A - 16.8V).

Options:

Specially tailored (Schottky) diodes --> simple/affordable, but a lot of wasted power and heat
Dedicated ICs (like a load switch) --> can't find one for my specs; either too little maximum current or too low maximum voltage
High side switch using P-MOSFET(s) or N-MOSFET(s) --> can't find/figure out the correct diagram/circuit logic for this, since they all handle reversed polarity protection, which is not the case here..

My question is: what IC or (MOSFET) circuit can I use to block the reverse current?

NB: Since the whole assembly will be mounted on a panel, there's no reversed polarity issue, only reverse/leak current from the battery to the buck module.


texts:
I am currently trying to repair my LG 27MP35 monitor and came across these foam blocks on the bottom of the motherboard:

At first I thought they were just something like spacers, but then it didn't really make sense because there are some contacts on the bottom of the board that they were glued to:

I don't have any idea what those are. They seem to also make contact with the back of the screen but I don't know what for.

My monitor is still not working and I want to know if these could be part of the problem. It seems like they have something to do with the problem because ater I replaced the mainboard of the monitor today and the screen was still not working, I noticed that these foam things were missing so I put them in place and it was working again. But now it's not working anymore even with the foam in place. I hope you can help me.


texts: Using BJT emitter follower after microcontroller

texts:
I am trying to understand an already existing circuit shown below taken from http://boris0.blogspot.fr/2013/09/rotary-dial-for-digital-age.html.

The aim of this circuit for the right part is to produce pwm signal, to filter it and to send dtmf signal back to phone line.

I was asking me if the purpose of the transistor is to adapt impedance of microcontroller output which is between 20 and 50 kOhms and the line which is around 600 Ohms ? Is it doing a kind of sum of this signal with DC of line ? Is it really working like emitter-follower ? (here we are not only taking Vout but Vout + Vce) How to choose R2 value ?


texts:
I have a bunch of 9V NiMH rechargeable batteries. I also have an adjustable CC/CV charger and to have battery fully charged with that I need to know the correct stop voltage.

I have read that 9V pack might have 7 or 8 cells so nominal voltages 8.4V & 9.6V and fully charged (1.35V per cell) 9.45V & 10.8V.

I know that I could safely use stop voltage 9.45V (so assume 7 cells) but if I want to have an 8 cell battery fully charged how can I determine it really has 8 cells without disassembling it?

Is the 8 cell version so rare that I should not bother even think about it?


texts: Use an old Nintendo NES Controller as an input device

texts: Does anyone have a pinout diagram for the Nintendo NES Controller? I'd like to connect the NES controller to an Arduino.


texts: Simple transistor & capacitor circuit question

texts:
I'm new to electronics, so what I've found to be helpful to a good learning process is examples.

Now, I was studying transistors and capacitors, and as far as I could understand, a transistor acts more or less like an "electrical valve/switch" and the capacitor store current until it's discharged.

To test what I've learned, I've made the following circuit:

What I though it will do was:

circuit being in the presented configuration, the LED will stay lit
when R1 is removed, the transistor ("valve"?) will close, the capacitor will gradually discharge, and the LED will fade away

But what the circuit actually does is

circuit being in the presented configuration, the LED will lit and imediatly fade out
when R1 is removed, nothing happens :(. When reconnecting R1, the LED will lit a little, then fade out. If I short the capacitor (to discharge it, I can tell this is maybe not recommended), then reconnect R1, the step 1 repeats again ...

Why does this happen? What did I got wrong ?

PS: the transistor is 2N2222


texts: I have a 12V 7Ah battery can I directly connect it to my device having rating 12v 1A? Will my device extract 2.25 amp current as it is betterys initial current or it will only extract 1 amp current. If yes will it damage my device


texts: Photovoltaic system that charges a Li-Po battery while supplying a 1.4V load

texts:
I am a mechanical engineering student and not that familiar with electronics.
I am currently trying to establish a photovoltaic (PV) system that can  charge a 3.7V 100mAh lipo battery and deliver power to a load (1.4V, 0.9mA) consistently (when there's sufficient input from PV, the battery charges and the load will be supplied by the PV <- charge mode; when there's insufficient input, the battery will discharge to supply the load.)
I have browsed some previous discussions and understand that if I want to charge a lipo battery safely according to the suggested charging algorithm, I should connect the solar panel, for example, 6V PV panel to a charging module like TP4056, and then connect the load and TP4056 with an LDO regulator to regulate the output voltage to 1.4V. However, people are suggesting that the load of the TP4056 should be disconnected while charging otherwise the TP4056 will not work properly. (https://www.best-microcontroller-projects.com/tp4056.html).
Is there any method to achieve my smart loading goal? (Providing consistent power to load either by battery/PV depending on the availability of input source.)
In this link, there is a method of using a 5V relay but as long as my input is a solar panel and is preferably a tiny system, the method should not be applicable. Furthermore, James suggested adding a pair of diodes in the circuit. However, I am a bit confused about "Add one diode between the TP4056 IN+ and load VIN+."  Where exactly should I add it in the schematic?  I am a bit confused about the principle behind this method.
This BQ24074 chip BQ24074 seems can achieve the goal but I am not so sure if it suits me as the maximum charging current can only be lowered to 500mA which is still much higher than 1C (100mA) of the battery I chose.

As an electrical engineering noob, I might have asked some silly questions, but I really hope someone can give me some insight into constructing this system.
updated photo for O'ring circuit


texts:
I am working on a datalogger to measure the voltage of a series of solar modules. I have 4 solar modules in series, let say 35V each. I am using an ADS1115 for the measurements. First I wanted to do differential measurements, but this is not possible as the voltage between the some of the pins of the ADS will exceed the max.

Now I will something simple, reference the series solar modules to the the measurement circuit and measure the voltage from the divider as in the drawing:

I want to add a voltage follower before the the voltage divider in order to not load the sources in a different way. The problem is I cannot find a (cheap) op amp to do this, that is rated above 150V. Is there a reason for this? I there another way to achieve a nice way to measure the voltage in series? how is it done on high voltage battery packs for example?


texts: Capacitor charging/discharging waveform confusion

texts:
This is the circuit:

At t=0s, switch is moved to position 1 and the time constant= 1ms

At t=10ms, switch is moved to position 2, it is assumed there is no leakage current

At t=20ms, switch is moved to position 3 and the time constant is 1.5ms

The waveforms of position 1 and 3:

So I understand what's going on before 10ms but what's confusing me is after it, so if the time constant after 10ms(position 3) is 1.5ms then after five time constant where the capacitor is supposed to be fully discharged then must be at 1.5x5 = 17.5ms but on the waveform it looks like it's saying after five time constant, the capacitor is fully discharged at 22.5ms, so what's going on ?


texts:
When I googled Miller integrator the sixth picture that popped up is this one, but I'm not completely sure what circuit it is and if it is something similar to the simple "standard" op-amp Miller integrator?
How is it different? (and HOW different are the two? If that question makes sense. )
The picture leads to the circuit implemented in CircuitLab, and the simulations I have done indicate that it does some kind of integration.

This is not really my field, but the circuits are very important for my thesis in mathematics, and the circuit attached seems very interesting for what I'm working on (even more interesting than the normal op-amp integrator).

Is the circuit realistic? How does it behave, and why?


texts: what does this schematic symbol refer to?

texts:
I have a schematic that has the intersected circles that IMOD and IBIAS arrows point to and I wonder about its meaning

edit :

if I know that this symbol is a current sink ..how can the Control IC change the current passing through the LD ? and how can I relate the resistor connected to IMODN to current in LD ?


texts:
Sorry for the lack of proper terminology, but I don't know how to approach even wording a question about this, not to mention search terms.

I've seen a lot of PCB-mount screw terminals that have these sort of slots that let you slide them together, with the one on the right starting out on top, and sliding down. Is the reverse of this available, with the one on the left starting out on top?

I am designing a board with 5.08mm-pitch screw terminals on opposite sides of the board, facing outwards, and I want multiple of these boards to "snap" together using the screw terminals.

Aside from part numbers, can anyone recommend even just some search terms? like what's that mechanism called, etc?

EDIT: I'm realizing I wasn't very clear. One of the terminals needs to have the whole dovetail system reversed, so that one board slides in from above the other board; otherwise I'd have to "twist" the boards together which seems sketchy. Also, I realize this isn't necessarily a good idea, but I want to give it a try unless someone can convince me it's a truly terrible idea.

EDIT: further clarification; I am not using this to make any electrical connections between the boards-- purely mechanical.

I'll post a sketch later


texts:
I've got an exact circuit diagram of the circuit in NPN, but I need to convert it to PNP. Could someone help, please?

I've got a 2N2907 with me right now and I want to make my High Level trigger into Low Level trigger. However all I have got is a low level to high level trigger circuit diagram.

The Relay Module I'm using is a Delay Timer Relay with LED Display for configurations and this comes with just High Level Trigger System. Hence I need a conversion of the Low Level Signal of mine from my sensor to be detected as High by the relay module.

The Module is
https://www.amazon.com/Docooler-Display-Automation-Digital-Control/dp/B07L968JKC/ref=mp_s_a_1_2?dchild=1&keywords=docooler+delay+timer+relay&qid=1590526628&sr=8-2

And the sensor is
 https://www.amazon.com/E18-D80NK-Adjustable-detection-infrared-obstacles/dp/B085MHHLMD/ref=mp_s_a_1_1?dchild=1&keywords=e18-d80nk&qid=1590526689&sprefix=e18&sr=8-1


texts: USB Type-C configuration necessary for battery charging only

texts:
I want to utilize a USB Type-C connector to charge a single battery that powers a device. The device will only function as an upstream facing port (UFP) or sink and no data communication will need to occur using USB2.0, USB3.0/3.1, or Aux pins.
What are the minimum components necessary (besides the Rd resistors) for the CC1, CC2, and VBus lines to use a USB Type-C receptacle to charge the battery off the VBus line? Will the source side recognize complete connection and orientation and know when to send 5V through to VBus or do I need to control that on the sink side?


texts: How does the voltage remain constant at secondary side of flyback SMPS when secondary current is decreasing linearly with time?


texts: Eagle - unabled to remove components in PCB view after removal in schematic

texts:
my schematics and board is completely out of sync and I'm trying to fix it. The error it gives are shown as following:

I want to solve this, and doing a little research I'm having this really unfortunate conclusion that I have to keep deleting things, everything, till the two matches perfectly, which is the last thing I want to do and everything I try to avoid, in Altium Designer, you can easily update either one based on the other with a click of a button, so I expect Eagle to have something similar, granted it would be much less convenient, but there should be a way other than keep removing things isn't there?

Or the entire software will fall right into the category of a bloody joke.


texts: Cascading PID DC Motor Position & Velocity Controllers

texts:
I'm trying to build a robot with a differential drive powered by two DC motors. First I implemented a PID Controller to control the velocity of each motor independently. Estimated the TF using the MATLAB's System Identification Toolbox, of the open loop system by the acquiring the velocity of each wheels encoder in function of the PWM signal applied by an Arduino microcontroller. All went well and I successfully dimensioned the PID gains for this controller.

What I'm trying to accomplish now is to control the exact (angular) position of the DC motor. I thought in cascading a PID controller in the input of the other already implemented. So this way, I can give a position to the first controller, which will be capable of generate an output reference to the second (velocity) controller so it generates the appropriate PWM value signal to drive the DC motor accordingly.

Will it work? Is that a good approach? Or should I try to implement a different controller which outputs the PWM signal in response to a position reference signal?


texts:
I have coax-connectors connecting two cable runs that are subject to weather. Typically weatherproofing is done by wrapping the connection in suitable tape. This is a fairly messy solution if the connector needs to be opened.

I am wondering if somebody had an alternative solution. Are there weatherproof coax connectors for RG-58? A waterproof box to replace the tape maybe? Typical frequency: 150 MHz.

Edit 1

Somebody had added an answer about gel-filled boxes(?) but deleted it before I could read it. If the answer was at least marginally relevant, please consider adding it again. I would love to see an alternative to tape. Text of the missing answer:

  [Gel Splice Closures][1] Gel-filled box Ensures complete sealing of coaxial splices Watertight...


texts: Mentor Graphics Xpedition DxDesigner Print

texts: Does anyone know how to fix this? One day my SSD died and after a system restore, I found a clean list of printers. I tried to reinstall MG EE but the problem persists.


texts: How to choose a 50 Ohm RF attenuator for radio, bluetooth and wifi power measurements

texts:
I have built a power meter with AD8318, a chip which contains a logarithmic amplifier, often used for power measurements.

I have read its datasheet and it is written that the maximum input power is equal to 12 dBm.

I do not know exactly which kind of measures I can do with this limits, but it correspondes to 15.85mW, which I think is quite low for many applications. Precisely, I wanted to use it to measure power from wifi networks, bluetooth, mobile network and radio stations.

So I need some advices about if it is necessary to buy a RF attenuator to put between the antenna and the power meter (with 50 Ohm SMA coaxial cable) and how many dB of attenuation I need for these applications. Since I am not an expert of rf attenuators, if you think I should consider other parameters for choosing an attenuator, tell me!


texts: In-line series identifier (eg. fixed bit flash) component

texts:
I'm looking to make a necklace of "charms", each having a different shape and containing a WS2812B (an individually-addressable RGB LED using a PWM-based single line protocol in series).

One of the aspects of this is that I'd like to be able to rearrange the "charms" (which are wired in series), and be able to read the new positions of the charms by sending a signal out along a single line (like the one for controlling the LEDs).

Is there any kind of similarly-cheap component that can pulse out a signal to uniquely identify itself in series like this? In my head, this looked like a fixed-memory "cell" that would output any bits that came before it, then add a few dozen bits of its own as a unique identifier.


texts: Changing Motor Gearboxes to Reduce Current

texts:
I am currently using two 12V CIM Motor (Spec Sheet: http://content.vexrobotics.com/docs/217-2000-CIM-motor-specs.pdf) with a gearbox at a 49:1 ratio.

I have a LiFePO4 battery that is rated at a continuous current draw of 25A or a peak of 70A for 30 seconds.  When the motor spun it was drawing 40A.  After a few minutes a sulfur odor was noticed coming from the battery.

How much do I change the gear ratio so that the motor draws less current?

Also how long would I have to turn the motor off between the 30 second spurts if I just ran at 40A on and off?

EDIT:
There are two motors that are being fed into one gearbox.
Battery Information: http://www.filedropper.com/ctcbatteryproductspec128v12ahv2

The two motors are for a robot drive system.  The 40A is for the total draw from the battery (2xMotors, Sabertooth 2x60 controller, arduino).  When the motor controller was commanded to go full forward on both motors 40A is drawn.

I can send a command to the motor controller to drive the motor slower.  Would it be more effective to send a slower command to the motor controller or change the gearbox so that the motor controller could use full throttle?


texts: Understanding the second transformer in PoE designs

texts:
I'm trying to understand the PoE reference designs contained in the datasheet and the evaluation board user's guide for the TI TPS23756.

The major difference between the "typical application" and the actual design they ship seems to be the role of the second transformer.

The schematic in the datasheet makes sense to me -- the control voltage for the chopper is phase-shifted, so it is synchronous to the current on the secondary windings on the main transformer, so using that signal for switching will give a DC signal.

The evaluation board instead builds a perfect diode to create a half wave rectifier, which is also a valid approach of course, but they still have a second transformer hanging off the gate voltage, and feed its secondary side to the current sense input on the PoE controller.

Is this really proportional to the current on the primary side of the main transformer?
Can I combine both designs, use a current sensing resistor on the primary side and a perfect diode on the secondary, and leave out the second transformer completely?
Am I missing something?


texts: Is it bad practice to install an IC to the other side of a heatsink?

texts:
Normally, we connect an IC to the other side of a heatsink than shown here:

Is it bad to place the IC on the 'unusual' side of the heatsink (and if so, why?) or are both sides each equally functional? In the end I will place the heatsink upside down in the case, so with the ICs on top of the heatsink.


texts: Is there a difference between voltage divider and attenuator?

texts:
I am thinking about using a voltage divider to scale down the signal by 2/3 (-1.76 dB) as the following circuit diagram:

When I googled with a keyword attenuator, I got a list of attenuators such  as:

(source: jyebao.com.tw)
With my poor knowwledge, they seem to be very similar. Is there a difference between a voltage divider and an attenuator?
Does an attenuator show a good performance when a signal has a high bandwidth? And a voltage divider is poor at manipulating a high speed signal?


texts:
Let's say I have the KVL of an RC circuit:

$$v_s = R~i + v(0) + \frac{1}{C} \int \limits_{0}^{t} i(\tau) d\tau$$

I take the phasor transform of both sides of this equation...much like a laplace transform:

$$P\bigg\{v_s \bigg\} = P\bigg\{R~i + v(0) + \frac{1}{C} \int \limits_{0}^{t} i(\tau) d\tau \bigg\}$$

I get:

$$V_s = RI + P\bigg\{v(0)\bigg\} + \frac{1}{C}\frac{1}{j\omega}I$$

but what's the phasor transform of a constant?

$$P\bigg\{v(0)\bigg\} = ?$$


texts: Where does the 0x get stored in memory while storing memory address in a register in a microcontroller

texts:
For eg. LDR R0, =#0x20000001
20000001 is now stored in R0 but where is 0x stored?


texts: Universal Voltage Divider Bias Circuit with both BJT and JFET

texts:
I am dealing with the following circuit:

I am trying to understand if I can just assume that, much like in the JFET voltage divider circuit, V_G = 10/(40+10) * 16V , or if the presence of the BJT after the JFET will affect the voltage at this point.

Any help is appreciated. Thank you so much!!


texts:
Good Day,

I am having trouble to compute the charging time of my battery with this kind of set-up:

(2) 300W 36V PV Panel
 (1) 500W 24V Wind Turbine
 (1) Hybrid Charge Controller
 (6) 12V 200Ah Batteries @ 24V Configuration

The batteries are connected to series-parallel connection that will give 24V 600Ah output.

How long is the charging time of my battery?

Thanks in advance! :)


texts:
I have a question regarding the UART baud rate error tolerance, as the thread title indicates. First of all, I want to point to an excellent tutorial on clock accuracy:
Maxim Integrated Tutorial

I understand that the baud rate error tolerance depends on many parameters, for instance, cable attenuation which is in direct correlation to the cable length, the baud rate itself etc. The UART baud rate on a dsPIC33E is determined by an \$\text{UxBRG}\$ register, which value is calculated as:

$$\text{UxBRG} = \frac{F_P}{16 \cdot \text{BR}^\star} - 1$$

where \$\text{UxBRG}\$ is a register of type unsigned int (16-bit), \$F_P\$ is the CPU clock frequency in Hz, and \$\text{BR}^\star\$ is the desired baud rate in bps.

For example, if we want a baud of rate of \$\text{BR}^\star = 19200\,\text{bps}\$, and the CPU clock frequency is \$F_P=60\,\text{MHz}\$, the corresponding register value would be 194.3125, which can be rounded to 194 or 195. The actual baud rate with respect to the \$\text{UxBRG}\$ register value can be calculated as:

$$\text{BR} = \frac{F_P}{16 \cdot (\text{UxBRG}+1)}$$

For the above example, the actual baud rate can be one of the following:

\$\text{BR}=19230.76923\,\text{bps}\$ (\$\text{UxBRG}=194\$) -> the baud rate error is +0.160%
\$\text{BR}=19132.65306\,\text{bps}\$ (\$\text{UxBRG}=195\$) -> the baud rate error is -0.351%

The baud rate error is calculated as:

$$\text{BR}_{\text{err}} = \frac{\text{BR}^\star - \text{BR}}{\text{BR}} \cdot 100\%$$

However, in the above example, although \$\text{UxBRG}=194\$ gives a lower absolute baud rate error (+0.160%), I would rather choose \$\text{UxBRG}=195\$ (-0.351%). The reason for this is that when a bit on the data bus toggles from 0 to 1 (or vice versa), the cable capacitance would "slow down" this transition, something like an RC circuit, which could even be 30% (or more) of the bit period. Of course, this depends on a cable length, the baud rate itself etc. Due to this reason, I would rather that the "baud rate clock" drifts from the center of the bit towards the end of the bit. Please let me know does this makes any sense at all.

P.S. Since in UART communication the clock resets itself on each frame, I know that everything under 3% baud rate error in "normal" operating conditions is considered to be acceptable.

Thank you in advance!

Best, Marko.


texts: What causes an induction cooker to lower heat level by itself

texts: It's more than 5 years old. It is difficult to cook in high temperature because the minus sensor appears to be activated all the time. I end up going from 1600 to 400 every time. What must be the reason for this?


texts: Practicality of a sound based electrical generator

texts:
I am wondering:-

Numerous electrical generators have been designed for every type of renewable energy I can think of; we have solar panels, hydroelectric dams and wind turbines, to name a few.

However, as far as I know, nothing like this exists to capture sound energy.

Other than a microphone, of course.

Now, I can only assume the reason sound has never been considered as a viable source of energy to capture is because the energy used by (most) sound must be very low. Please tell me if this is wrong.

Even if just one microphone produces a very small current, couldn't a large array of microphones ultimately amplify this to a useful sum of energy?


texts:
What are the structural differences between Serial NOR Flash and Parallel NOR Flash? If there is a structural difference , then What are the differences between Serial NOR Flash and Serial NAND Flash?
I can't seem to get the resource for this particular question from Googling


texts:
I work in the field of spectroscopy, for instance NMR and FT-IR.  For both of these instruments, the advice is to process the data to compensate for heteroscedasticity -- noise that increases as the signal increases.  Let's focus on NMR: the receiver in NMR is a small (~5 mm diameter) solenoid-like winding of wire that acts as an antenna to pick up the signal from the decaying nuclear spins.  The response in the antenna is captured by an ADC. The whole experiment occurs in a strong and ideally homogeneous magnetic field.

I'm wondering, in general, how do we know in this situation that the noise will increase when the signal increases?  It might be helpful to have a counter example of some instrument where the noise is constant regardless of the signal size (homoscedastic noise). I know very little about EE, so I'm hoping for a fairly simple explanation.  If the answer is something along the lines of "in the real world things are always heteroscedastic" perhaps someone could include some of the factors that contribute to the noise.


texts: Do bank/rows/columns based NOR flash memory exist?

texts:
SDRAM supports more addresses than their address bus width allows thanks to the bank/row/column scheme it's based on.
My question is if there are non volatile parallel memories that are based on the same bank/row/column scheme so they can support further addresses than the address bus lines allow. After a quick search in various stores I guess that the answer is NO. If not, why?


texts:
I would like know your opinions on my circuit. I have LED strip which is consists from 60 ws2812b chips. I want switch power ON/OFF by N-MOSFET. My question is about using flyback diode. I read that is recommended use it with LED strip to protect MOSFET, but I think it is unnecessary. Next I don't know if is possible combination flyback diode with electrolytic capacitor.

Thanks for your responses


texts: How do I make the LM3914 (LED) Bar-graph driver IC make the LEDs light up brighter?

texts:
Like I said in the title, I am using the LM3914 IC to drive a 10 segment LED Bar-graph. The actual subsystem has the signal pin on the IC connected to a capacitor, thus displays the amount of charge the capacitor is holding on the Bar-graph.

I've done a test of my entire circuit on a breadboard and found that every subsystem - including the bar-graph circuit - worked a treat.

However, the LED segments on the Bar-graph are so dim that they are barely visible under bright light. Is there a way of making the 3914 increase the current through the LED segments to make them brighter?

Here is a rough schematic of the circuit I am using:

(Supply and resistor values are actual)

Any pointers would be extremely helpful thanks!

Here is the specific bar-graph if it is of use:
https://www.kingbrightusa.com/images/catalog/spec/DC10GWA.pdf


texts: Can lightning damage electronics via a ground connection?

texts:
Often when we think of a lightning transient, the idea is that the lightning strikes a power line and propagates through the hot/neutral or 3 wires of 3-phase system. There is also induced current transients.

However, I wonder to what extent lightning can affect the ground system. Most houses where I live are grounded to the water pipe in the house, so I would guess that if the lightning hit say a bridge with a water main on it, it could affect equipment attached to that water line. One article on lightning surges had the paragraph:

  Lightning ground current flow results when a strike that discharges to
  the earth couples into common ground impedance paths, causing voltage
  differential across the ground grid and between ground-neutral or
  ground-line circuits. In short, the reference ground (supposedly zero
  voltage) is elevated a few milliseconds, therefore creating a large
  voltage difference between ground and the incoming power and/or data
  lines.

To what extent, if any, does lightning affect ground systems which use water pipes?


texts:
I have designed a pre-amp and I am having a lot of noise when silent. It seems to be around 70 Hz on my scope, but jumps around.

I've tried adding bypass filters on the NPN emitter legs, as well as high-pass and low-pass filters on the signal line, without luck. I am not sure how to reduce this without firmware. The source is a clean 5 V supply straight off a battery, to eliminate any supply noise issues. I am really stumped!

Is there any way to reduce this? Decoupling caps on the main bus don't help either.

Thanks for the help! Please let me know if I am missing any information :)


texts: As I simulated the circuit below, it shows that the potential difference across Cx is the amount of potential being stored on C3 and C4 during charging phase. How do we get the potential difference of a capacitor? And how did this happen? What theory is behind this operation?


texts: How to test a laptop keyboard from its ribbon cable

texts: Is there a way to test a laptop keyboard from at its ribbon cable, fully disconnected from the motherboard? Some kind of switch continuity or something along those lines that would indicate whether a particular key is working or not. Is there a related test to do at the ribbon connector at the motherboard


texts: How to use voltage division for series-parallel circuit

texts:
We know that:
A voltage divider is a simple circuit which turns a large voltage into a smaller one. Using just two series resistors and an input voltage, we can create an output voltage that is a fraction of the input.

But I am unable to figure out \$V_x\$ across the 6 ohm resistor.

The 12 and 6 ohm resistors in parallel threw me off.


texts: Why 2 pole induction motors don't use auxiliary windings while running (while others do)?

texts:
Most motors with more than 2 poles I see (4 poles, 6 poles etc) use a run capacitor and a use the auxiliary winding all the time. Some even employ starting capacitors but they always have a run capacitor.
But why does 2 pole motors only use the auxiliary winding for starting? I haven't seen any single phase 2 pole motor that use a run capacitor.


texts: The Complex Power from a source V = 200cos(wt) is 200 + j150. The impedance across V is given by what value?

texts: I found the answer using P = V^2/R and by using P = VI*. In both cases, I got the answer as 128 + 96j. But the answer given is 64 + 48j. Which is the correct answer?


texts: Vivado is not properly gating my registers?

texts:
I have a register which holds 12 bits written in VHDL within Vivado which is not being gated properly. The code is very simple, and is as follows:

library ieee;
use ieee.std_logic_1164.all;

entity reg12b is
    port (
        reg_in : in std_logic_vector(11 downto 0);
        load, clock, clear : in std_logic;
        reg_out : out std_logic_vector(11 downto 0)
    );
end reg12b;

architecture description of reg12b is
    signal internal_value : std_logic_vector(11 downto 0) := "000000000000";
begin
    process (clock, clear, load, internal_value)
    begin
        if rising_edge(clock) then
            if (clear = '1') then
              internal_value <= "000000000000";
            elsif (load = '1') then
                internal_value <= reg_in;
            else
                internal_value <= internal_value;
            end if;
        end if;
    end process;
    reg_out <= internal_value;
end description;

As you can see, this holds 12 bits, and has a synchronous reset function. This is what it synthesizes to in Vivado. As you can see in the blue highlighted line, the Flipflop is an input to the LUTs, but another input to the LUTs is the inputs. I've tried refactoring my code a large number of times, and it never seems like I can put the flip flops as the sole output.

The code produces strange setups akind to the picture below. This sort of construction is not desirable, as it creates large timing hazards across the entire design.

I want the entire design to be gated, moreso as follows:

How do I tell Vivado that I want it to design the second picture, and not the first picture?


texts: Driving a PWM controller with an SMPS - Does my motor like it?

texts:
SMPS Power supply: MP 3800

I have a 12V brushed DC motor hooked up to a PWM controller. When I run the motor (all works as it should) however there is a lot of crackling noise coming from the PSU.

Note: Snubber diode (or 'Flyback' diode) added due to PWM Controller manual recommendation.

Considering the PSU has its own PWM...am I creating dirty power by chopping the signal once again with my PWM controller?

simulate this circuit – Schematic created using CircuitLab


texts: Voltage across transformer primary to secondary - ways to mitigate

texts:
I am trying to galvanically isolate my electronics from the Mains and isolate Earth, so have placed an isolation step-down transformer (230:20) in between the Mains and my electronics.

If I measure from load (which is across the secondary) or the secondary terminal to primary terminal, I am seeing Voltage. The two terminals of the secondary show different voltages with respect to the two terminals of the primary, but both the secondary terminals show voltage with respect to both the primary terminals.

The above readings differ from multimeter to multimeter, some not showing any voltages at all. I am sticking to Fluke multimeter.

I guess this is capacitive coupling.These voltages do not disappear even when the secondary is loaded.

I got my transformer maker to make a transformer with shield in between and grounded the shield. Still the cross-voltage only worsened.

As the source of this voltage is capacitive coupling, I guess this will allow AC noise to be transmitted to the load.

I would like to know if it is possible at all to completely decouple this cross-voltage from the secondary and if yes, by what means ? Can this coupling convey primary side noise and fluctuation to secondary side ?

On the secondary side, I have a switching regulator supplying regulated voltage to an electronics instrument. I do not want secondary side to refer to Earth.

Thanks in advance.


texts: Writing DSP algorithms directly in C or assembly?

texts:
I m working on a DSP project(IIR filtering) on an Analog Devices digital signal processor(BF706) with the compiler suite coming with it, CrossCore Studio. It has some examples for simple DSP stuff like FIR and IIR filters and library functions for it. The processor manual describes the assembly instruction set and doesn't comment on C.

MY question arises from this particular application, but I thought there is a best practice that DSP developers follow. So I will frame it in a general way:

What I have realized by the examples coming with this DSP, is that if I want to use the circuits designed for DSP applications I need to program in assembly to directly run those instructions.(like multiply and add, etc. ) My question is if I just program in C, wouldn't the compiler(which also comes from the DSP chip company) optimize it for that DSP and use its capabilities? Or do I really need to write DSP routines directly in assembly?


texts:
I have a few questions regarding an H-Bridge design that I like. I am having a little hard time understanding some parts of it.

So this is the design that I found online here.

I changed the motor voltage and the resistor values to the transistors from 10k to 3.3k. So the questions I have are

1) Are the 10k pullup resistors too high for the P-Channel Mosfets? Should they be lower?

2) For the N-Channel Mosfets, why is the 9V voltage going to a 10k resistor then a transistor to ground? Can't I switch the N-Channel side with something like this?

3) Are the resistor values going to make switching slow for the N-Channel Mosfets?

I plan on running the H-Bridge using an arduino. The N-Channel Mosfets are FQP30N06L and P-Channel Mosfets are FQP27P06. I plan on using the 2N2222a transistor.

Are there any problems with this design that I am missing or misunderstanding or should everything work as expected? Thank you.

Also when connecting the ground of the 9V source do I connect the ground of the arduino to the ground of the mosfets and transistors? Ground is always the same everywhere, correct?


texts:
I've got a pretty...awkward project, to try to simplify my life with the great many devices being plugged/unplugged, the clutter of cables around my desk, and the general awkwardness of it. The theory is simple: bind as much as possible into the desk.

The first step, and possibly the most important one to reduce the crazy number of power cables, would be to try to build the power sockets for various devices into the desk. This is where my dilemma comes in:

I'd really like to reduce the size of the power plugs from the UK standard to something preferably smaller. Obviously, I want to keep all three separate pins, and I'd prefer a connector that is as easy as possible to find (as I'll have to strip quite a few plugs bare). The desk will still have the odd UK socket due to devices that come with a wall converter, but I'd ideally like to have as few of those as possible. What kind of connector pair would handle 220V with up to 6A current draw?
I'd like to digitally control the supply of power to the said sockets. Arduino programming is not an issue - soldering is not an issue - heck, anything electronics is not an issue. What would be the best solution? Thinking solid state switches but I don't think that this is the best approach for it.
Is there anything obvious in terms of safety barring me from possibly doing this?

Any input on any of the three points would be more than appreciated. There are a few other things planned for it (homebrewed KVM) but this should not be an issue.


texts:
I have a device in which a reed switch is encased in potting compound. (So impossible to identify.) My problem is, that for my application the switch is too slow.

I am considering replacing it with a hall-sensor switch like these. Is it possible to make an educated guess which switching threshhold I am going to need under the assumption that the reed switch is a "common" / "cheap" part? - Or whether any of these will work at all...


texts:
I'm trying to upload a hex file, generated from multiple C source files with xc8 in Proteus, into a PIC18F4520. Usually, I don't have any problems doing this but yesterday I ported some Arduino TFT display code to the PIC and tried to upload and test some basic screen functions. The HEX was uploaded and the PIC drove the screen perfectly except for a problem with the colour of text. I went through the code and found the problem was due to a variable that I accidentally declared as uint8_t instead of uint16_t thereby causing the colour to be truncated. The variable is one of a bunch of static variables with file scope:

static uint8_t _width    = ST7735_TFTWIDTH;
static uint8_t _height   = ST7735_TFTHEIGHT;
static uint8_t rotation  = 1;
static uint8_t cursor_y  = 0;
static uint8_t cursor_x  = 0;
static uint8_t textsize  = 1;
static uint8_t textcolor = 0xFFFF;  // this is the relevant line
static uint8_t text_wrap      = 1;
static uint8_t colstart = 0, rowstart = 0;

I corrected the declaration and built a new HEX in Proteus and tried to re-upload with the PICkit 2 application. When I imported the hex file to begin the upload, I got the warning: Hex file loaded is larger than device, which didn't make any sense since the memory summary is:

Memory Summary:
    Program space        used  17DBh (  6107) of  8000h bytes   ( 18.6%)
    Data space           used    6Dh (   109) of   600h bytes   (  7.1%)
    Configuration bits   used     7h (     7) of     7h words   (100.0%)
    EEPROM space         used     0h (     0) of   100h bytes   (  0.0%)
    ID Location space    used     8h (     8) of     8h bytes   (100.0%)
    Data stack space     used     0h (     0) of   580h bytes   (  0.0%)

Inspecting xc8 output in MPLABX this time, I found this message at the bottom: Warning: C:/.../train85.X.production.hex contains code that is located at addresses that do not exist on the PIC18F4520. This correlates with other answers I found online; it seems code is being written to non-existent addresses. The methods used by others to solve it seem varied: some made changes to the arrangement of CONFIG variables, making them more compact (which I've tried) while others edited the HEX itself manually. Some observations that may be pertinent:

If I undo that single correction to the declaration above, the warning is no longer present.
There are 2 large arrays for font details, that are stored in program memory with the const keyword. They are about 2.4k in size and are accessed through pointers in structs.
If I move one of the font arrays to data memory by removing the const qualifier, the warning also goes away.
When I ignored the warning and uploaded the HEX to the PIC with the PICkit application, there didn't seem to be any problems; the TFT display was driven perfectly and the text colour issue was solved.

The HEX, SYM, MAP and startup ASM files, pre- and post-correction, are located here in case you need them. I can't post my code here as there are several files, but I can provide a link to it, if necessary.

In case my question wasn't clear, I need to know the exact cause of the warning, as it relates to my code (HEX) and a solution to it. Is it safe to ignore it, like I did? Thanks in advance.


texts:
We are trying to debug a host SD card interface (4bit SDIO) and am having trouble finding a logic analyser that can do a full stack decode.

So my 'dream' device would be a logic analyser that can emulate any brand of SD memory card in FAT32 or exfat format, with a full trace playback of all data reads and writes, and how that effected the file system.

The issue we are having, is the file systems FAT table is corrupted after several hours of writing to an SD card.

There are solutions like this http://www.digikey.com/products/en?mpart=FRONTLINE%20SD&v=1133 (at $8k mind you). but it seems that only decodes the data layer, but doesn't give you the context of how the FAT and data files on the card would be effected.

Does anyone know of a solution?


texts: Analog input dependent on samples quantity used in averaging

texts:
I found this issue using arduino but IMO this relates more to electronic eng.
I use pin0 without any pull-up/pull-down/connection.

Simplified code:

if (samplesQty >= 5000){
  Serial.println(buffer/samplesQty);
  buffer = samplesQty = 0;
} else {
  buffer += analogRead(0);
  samplesQty++;
}

The question is why do I get value ~450 (out of 1024 max) if I take 2 samples, ~390 if there is about 800 samples and 25 if there is 5700 samples?

I'm definetly not taking all these samples consequently, i.e. if there is 800 samples, I do 1 ms delay after samplesQty++, all samples are taken in less than 1 second.

Thank you in advance.

p.s.: I know how to get steady zero while 'in the air', the question is kind of theoretical.


texts: Stepper motor failing. Electrical interference?

texts:
Update:  This question is already so long, I'm hesitant to add to it but it occurs to me to ask if electrical interference between the stepper motor wires could cause this sort of behavior (motor oscillating, freezing, turning wrong direction for a moment)? The wires, standard ribbon cable, snake through the plotter "H" frame in cable carriers and are not shielded in any way. The failure is intermittent and only of the "far" (from the power source) motor) is failing.

I don't have the mad electrical engineering skills to accurately diagnose a subtle interference problem. Is there some brute force shielding "band-aid" I can try?

Background: I've built a 6' x 6' 'H' style plotter as a drawing machine (video of test run). It has 2 stepper motors controlling the Y axis and 1 stepper for the X axis (the "bar" in the "H"), layout below. The Y axis motors branch from the Y axis stepper driver and the wiring on the "far" motor is reversed so that the motors move the carriage in the same direction. There is also a smaller stepper for the Z axis, which is powered but not used yet.

I am using matched stepper motors for the X and Y axes (specs below). They are rated at 5v 1A. I am controlling this whole thing using an Arduino and a grbl shield. The grbl shield uses TI DRV8818 stepper drivers which are rated at 2.5A. I was powering the motors first with a 24v 3A max bench power supply and today tried a 12v 20A power supply. I have a small fan to cool the board.

Problem: The "far" (from the power source) Y axis stepper is intermittently failing. When the problem occurs it stutters (as though it were wired incorrectly) or doesn't turn at all.

I realize that it is hard to diagnose a problem like this from what I have provided but maybe there is something I can test? Here is what I have done so far:

Switched the Y axis motors to check if there is actual motor failure.
Again only the "far" motor failed, so the motors seem ok.
Removed the load (removed the belts) so the motors could run free.
Similar failure symptoms on the "far" motor.
The stepper drivers are "chopper" type (variable current) and the
grbl shield has current adjustment pots for each axis so I've tried
dialing the current up and down.
I've tried various feed rates (affecting the speed at which the motors
turn) as well as testing other settings (acceleration, etc).

What I don't get and am really stumped by is why only one of the Y axis motors is failing? The "near" motor works fine. If my power supply was inadequate or the stepper drivers were in thermal shutdown, both motors should fail.

Long-winded question, I realize, but I have tried to provide as much detail as possible. I don't know what else I can try to diagnose the problem.


texts: How many bits are used for the tag, block, and offset fields for the representation of a memory address?

texts:
A small byte-addressable embedded computer system, with a word length
  of 32 bits, has a main memory consisting of 4 KBytes. It also has a
  small data cache capable of holding eight 32-bit words, where each
  cache line contains only two words. Consider a direct-mapped cache.

Answer

Since the cache is direct-mapped, the size of the set is 256 bits (?) = 32 byte and therefore it takes 5 bits to address the memory, so the number of bits that are not the tag is 5 (?) = 27 bits are used for the tag (?)

Since a line is 2 words = 64 bits (?) = 8 byte then the offset takes 3 bytes and therefore the block takes 2 bytes (?).

Is it true?


texts:
I'm marginally familiar with the way that an AC transformer works.  After viewing this question:

Why don't all motors burn up instantly?

It got me thinking about the same thing with AC transformers.

The primary coil should provide very little resistance and thus allow a lot of current to flow.  I'm guessing that the resistance comes from the fluctuating magnetic field.  Is this correct?  If so, I'm assuming that the current increases when a load is placed on the secondary coil because the magnetic field doesn't collapse into the primary coil but is used by the secondary coil instead?

Also, does this mean that if a DC current was placed on a transformer that it would cause trouble? (i.e. very high current)

I'm sure I'm not saying this correctly, so I'm hoping someone can set me straight.

To sum up my question, what is the behavior of a transformer's primary coil (in terms of current flow) when no load is placed on the secondary coil, and what changes when a load is placed on the secondary coil?


texts: For the following amplifier, why is the output voltage 0 when input voltage is 0?

texts:
The amplifier is the following class AB amplifier:

For an input voltage of 0V, the output voltage is 0V. However, I don't understand why. My textbook does not delve into why this is the case.

(Also VBB/2 is large enough to turn on both transistors with no input voltage.)


texts:
I've found some 400V 0805 resistors. However, as in my previous question, I noted that almost no power supplies used surface mount components.

One of the things I'm working on is a capacitive power supply. This is connected to the mains and has no isolation, but operates inside a completely sealed box so there is no hazard to the user there. However, I'm not entirely sure if it's okay to use 0805's when dealing with such high voltages... it just seems like arc-over or something similar would happen. And, say there was a fault - would through hole be better at handling a line transient than SMT?


texts: Reprogramming a computer mouse's internal IC?

texts:
I have a mouse with an internal IC: SPCP168A, having read about it, I discovered that it is specifically designed and programmed for the mouse functionality.
I am interested in reprogramming the device to be able to use its "camera" (160frame/s).
My questions are:
Can I reprogram it, or is it an OTP?
Has anyone done something similar ?


texts: Using multiple NPN transistors with resistors from base to ground

texts:
Apologies in advance if this is really simple and I've missed the obvious!

I understand that there are benefits to having a resistor before the base of a transistor going directly to the common/ground (for example R4, R5, and R6).  I have been successful when working with individual NPN transistors, however, I found that when they're wired the way they are in the schematic, it caused issues with the other transistors becoming unpredictable even when they're supposed to be off; which makes perfect sense I think.  Is there a way to do this that works as intended?

R1, R2, and R3 will be receiving PWM input from an Arduino to control a 12v supply going to several motors.  Common/ground is going to the Arduino GND pin too.

It was around two years ago when I last did anything to do with electronics, so I am little rusty; I just wanted to see if I can get it right before starting without head-scratching for hours over something hopefully simple!...

Thanks for any help! Much appreciated!

Edit: I've left out the fly-back diodes and resistors for the motors to keep the schematic simple.

Edit: "Updated version" schematic is in response to Tony's reply.

Final Edit!: Re-added that I left diodes and resistors out of the original schematic to reduce clutter.

simulate this circuit – Schematic created using CircuitLab


texts: Device to programmatically controlled USB relay/switch

texts:
(Edited to remove shopping question.  I don't need recommendation of a specific product as much as I would like to know what such a device would be called.)

I'm know more about programming than I do about electronics, and I'm looking for an inexpensive way to programmatically open/close a low voltage circuit.

I imagine there must be some sort of simple USB controllers; I'm probably just not using the right search terminology.

I'd have a few applications for such a device.  One example: I can already receive real-time household temperature & humidity data with a USB sensor like this.  I can collect and analyze that data in Windows (with VBA in a Microsoft Access database, for simplicity's sake), but I also want to open & close the low-voltage control circuit for my furnace, for both real-time temperature control, as well as analysis and experimentation.

What would a device like this be called? Expensive solutions would be counterproductive since the overall objective is to save money, not spend it!


texts: Measuring leakage current in a capacitor

texts:
I've recently been hired in a lab at my university to continue research on supercapacitors, specifically leakage resistance. The former student who set up the current tests was a chemist so the professor wants me to verify all of the testing procedures.

In my research about measuring capacitor leakage, manufacturers of electrometers (or other high input impedance devices) say that you must supply the capacitor with a constant voltage to measure Rleak and it will subsequently decay over time. My question is why should a constant voltage be applied and why would this make Rleak decay? Wouldn't it be constant? It seems like a better test to me would to fully charge the cap, then disconnect the power supply and measure how much current is then leaking as a function of time.

Any thoughts on this?


texts:
I am using PSIM to simulate the TL431, and I have some questions.
This is my PSIM circuit:

When Vref is less than 2.5V, the TL431 doesn't conduct, it looks like an open circuit so Vo is almost 5.1V.
When Vref is higher than 2.5V, the TL431 conducts and Vo is 2V.

I re-drew the TL431 circuit.
This is the TL431 circuit:

This is the TL431 equivalent circuit:

This is current flow in the TL431 circuit when V+ is more than 2.5V:

This is an info sheet about the TL431:

There are my questions:

Why is Vo 2V? How do I calculate this voltage?
When the TL431 conducts, why doesn't Vo connect to the ground like the third figure?
I see someone says when the TL431 conducts then Vo is 2.5V. I don't know why.

This figure is from Ti Design a Flybuck Solution With Optocoupler to Improve
Regulation Performance.


texts: LT1172 Spice model: switch current too high?

texts:
I am using LTSpice IV for Mac, which includes a model for the LT1172 switching regulator. Downloaded the demo circuit from LT's website (this one). Ran it. Upon right click on the LT1172 symbol, I could also open another test circuit. Simulated this one as well.

Now: in the first circuit, at startup the switch current goes far above 2 A; should not it be limited to 1.25 A? And in the second circuit, the same behaviour at startup, and the current stays above 1.5 A even in steady state...

Am I missing something?


texts: How do I connect an Arduino to a landline?

texts:
How do I connect an Arduino to a landline telephone wall outlet?

I'm thinking of home automation, something like:

I call my house, and after a few rings the Arduino picks up the phone
The Arduino somehow (modem? synthetic voice?) tells me the house temperature and whether I've left my garage door up and all the lights turned on.
I somehow (modem? whistling Morse code?) tell the Arduino to lower the garage door, turn off all the lights, and adjust the temperature setpoint down a few degrees.

Is it true that connecting stuff to a landline (i.e., technology developed in the 1870s) is less complicated than connecting stuff to some sort of cell-phone network or cable TV Internet access?

(This is a different question than " I'm looking for a low-parts-count Arduino <-> phone & POTS line interface " , right?)


texts: What is the difference between those 2 logic gates symbols

texts:
I was wondering the difference between two symbols (we can found the diagram page 2 at http://www.onsemi.com/pub_link/Collateral/MC14040B-D.PDF )

Between the logic gate NOT (a triangle then a circle) and the other symbol (a circle then a triangle) which is located in the right of the CLOCK10

I searched on the internet but I only find information about the NOT gate (and nothing about the other one)

Thank you very much,


texts:
I wrote a simple frequency counter program in which TMR0 is 500ms timer and TMR1 as counter.
Everything is working fine but what i din't understand is that TMR1 register output is  hexadecimal or is decimal. Since input to TMR1 reg is in hexadecimal why my output is in decimal. Input frequency is supplied from 5khz square wave and TMR0 is prescaled to 256.TMR1 no prescaler.
I set the input to TMR1 register as

    TMR1L=0x00;
    TMR1H=0x00;

but after 500ms timer my TMR1 register value is

    TMR1L=243;
    TMR1H=8;


texts:
In a github project I saw a feature as follows:

  Support for writing to custom shadow configuration space.

I know what PCI config space is but what is a "shadow configuration space"? I google'd but could not come across anything that explains it clearly.

Here is the link to the project: https://github.com/ufrisk/LeechCore


texts:
I have a question about how SR latches work:

To my understanding the real-world implication is that one of the two gates will receive power first and produce an output signal, and they aren't going to turn on at exactly the same time.

For simplicity assume top gate is "gate R" and bottom gate is "gate S."

Is it conceivable that both gates are powered up before the signal from one gate reaches the other?

Say gate R receives power, interprets 00, outputs a 1, but before that signal reaches gate S, it also powers up, interprets 00, outputs a 1.

And so both gates would be outputting 1 briefly until gate R's 1 output finally reaches gate S and causes it to output a 0.

Meanwhile gate S's original output of 1 is heading back to gate R and causes it to change from outputting a 1 to outputting a 0 as well, etc etc etc?

I'm struggling to understand how it all fits together, the timing implications, and where the delays are and how they're enforced and what can happen vs. what can't happen, etc.


texts:
So I was at the dentist's yesterday, and we were talking about dental technology, and how for example RX (Röntgen, aka X-ray) sensitive CCD have replaced photo-chemical RX in dental imaging. I forgot to ask her what the lifetime of her sensor was, but I've always learned that RX is Very Bad™ for ICs. I don't think CCDs are an exception.

Are there techniques which make an IC less vulnerable for RX rays, or will my dentist have to replace her sensor 3 times a year?

edit
Talked to my dentist again this afternoon, and asked her about the sensor. She's been using it for 7 years now, so it doesn't seem to be so much of a problem.


texts: 12 bit ADC conversion simple code not working as expected

texts:
I posted a couple days ago a couple of functions that I wrote to do 10-bit ADC. the problem is I couldn't figure out what was wrong with my code so I wrote a much simpler single function that does a 12bit conversion for an easier troubleshooting of the orginal code. So my code works now for the most part but I have one small issue that I can't figure out by my own. I set 2 leds to light up when input voltage is above 2.5 volts and only one to light up when it is under. The problem is when the voltage is under 1v the two leds still light up. but besides that everything works as expected as soon as I go above 1v the single LED comes on then When I go above 2.5 volts the other 2 LED light up as expected. I would really appreciate any suggestions Thank you for your help. I am using PIC16f1788

  #include <xc.h>

 // Config word
#define _XTAL_FREQ   2000000 // set it to match internal oscillator

/*config1 and config2 settings*/
// CONFIG1
#pragma config FOSC = INTOSC // Oscillator Selection (INTOSC oscillator: I/O function on CLKIN pin)
#pragma config WDTE = OFF // Watchdog Timer Enable (WDT enabled)
#pragma config PWRTE = ON // Power-up Timer Enable (PWRT disabled) (turned on!)
#pragma config MCLRE = OFF // MCLR Pin Function Select (MCLR/VPP pin function is MCLR) (turned off)
#pragma config CP = OFF // Flash Program Memory Code Protection (Program memory code protection is disabled)
#pragma config CPD = OFF // Data Memory Code Protection (Data memory code protection is disabled)
#pragma config BOREN = ON // Brown-out Reset Enable (Brown-out Reset enabled)
#pragma config CLKOUTEN = OFF // Clock Out Enable (CLKOUT function is disabled. I/O or oscillator function on the CLKOUT pin)
#pragma config IESO = ON // Internal/External Switchover (Internal/External Switchover mode is enabled)
#pragma config FCMEN = ON // Fail-Safe Clock Monitor Enable (Fail-Safe Clock Monitor is enabled)

// CONFIG2
#pragma config WRT = OFF // Flash Memory Self-Write Protection (Write protection off)
#pragma config VCAPEN = OFF // Voltage Regulator Capacitor Enable bit (Vcap functionality is disabled on RA6.)
#pragma config PLLEN = ON // PLL Enable (4x PLL enabled)
#pragma config STVREN = ON // Stack Overflow/Underflow Reset Enable (Stack Overflow or Underflow will cause a Reset)
#pragma config BORV = LO // Brown-out Reset Voltage Selection (Brown-out Reset Voltage (Vbor), low trip point selected.)
#pragma config LPBOR = OFF // Low Power Brown-Out Reset Enable Bit (Low power brown-out is disabled)
#pragma config LVP = OFF // Low-Voltage Programming Enable (Low-voltage programming enabled) (turned off)

unsigned int analog_reading;
unsigned int i;
unsigned int bit_val;

void main(void)
 {
    //SET UP
ADCON1= 0b00000000; //format setup see page 182 of datasheet
TRISA= 0b11111111; //sets PORTA as all inputs
TRISC= 0b00000000; //sets PORTB as all outputs
PORTC= 0b00000000; //sets all outputs of PORTB off to begin with
ADCON0 =0b00000101;
               // bit0: ADC enabled
               //bit6-2: AN1 enabled for analog input
               //bit7: set for a 12-bit result
               //

while (1)
{
__delay_ms(10);
ADCON0bits.GO_nDONE=1; //do A/D measurement
while(ADCON0bits.GO_nDONE==1);
bit_val= ADRESH; // store upper 8 bits in a 16bit variable
analog_reading = ((bit_val << 4) | ADRESL); //shift it up by 4 bits then store      ADRESL in the bottom 4bits
                                        // According to page 184 of datasheet   when ADFM=0 ADRESH has the
                                        // upper 8 bits of 12bit conversion results and the lower 4 bits are in ADRESL

 if(analog_reading>512){    // when the voltage is passed 2.5 volts these two  LEDS should come on.
            /*Turn these 2 LED on*/
            PORTCbits.RC2 = 1;
            PORTCbits.RC3 = 1;
            PORTCbits.RC4 = 0;
            }
else{
            /*turn one LED on*/
            PORTCbits.RC2 = 0;
            PORTCbits.RC3 = 0;
            PORTCbits.RC4 = 1;
            }
  }
  }


texts: Matching oscilloscope impedance to detector

texts: I have a detector with a preamp that has an output impedance of \$50\Omega\$. My oscilloscope has an input impedance of \$1\rm{M}\Omega\$ and capacitance of 16pF. The signals I'm interested in are on the order of 10MHz. What is the effect of my oscilloscope not being matched to the preamp?


texts: Can I transmit in the ISM band without a ham radio license?

texts: I recently purchased a HackRf SDR, which has transmit and recieve capability. I'm debugging a 2.4ghz wireless module, and being able to transmit to it using the hackrf would be very helpful. Since this is in the ISM ("unlicensed?") band, can I transmit legally (with a very low power, a few milliwatts) for testing purposes without an amateur radio license? I'm in Canada, by the way.


texts:
I am a complete beginner with electronics mostly dabbling as a hobby so please forgive me if I struggle to follow or don't understand specific terms.

I have been working on a project for a while now with the intention of controlling multiple 'haptic' devices via 3.5mm connectors with the help of an Arduino nano,
it is my hope I will be able to incorporate it into VR and create some custom controlled haptic feedback

unfortunately, my first attempt seems to have been a failure and I am unsure why

ultimately I wanted to be able to control 6 up different devices via the 3.5mm ports
my initial attempt was through the use of an L295D chip which I had seen used in multiple video tutorials online, however when I tested this nothing happened and no power was getting to the motors, either I have misunderstood how the chips work/should be wired. or I have somehow broken them

if anyone has any ideas as to how I could go about this or can see and obvious flaw in my design I would appreciate the input


texts:
I have a Canon SX210 IS which has not a connector to use a external power supply. So I wanted to connect "my" power source to the pins the battery usually touches.

In the back of my camera, it says 4.2 V but the battery has 3.7 (model NB-L5).

Right now, I have in my hands a voltage regulator (7805) and a diode which would drop 0.7 V.
I plan to connect the 7805 to a car battery so there is no line noise. Do you know if it safe to feed my camera with those 4.3 V?

Should I use less voltage? Would the camera be damaged if I pass 4.2 V?

I haven't tried anything yet just for precaution.

Thanks in advance!

EDIT

Does somebody know about a voltage regultor with arround (3.8 - 4.3)V of output?