texts: Connecting phone using copper power wires

texts:
I want to install a video door phone (intercom) in my home, for this I have done a pre-wiring of 4 individual copper wires (normally used for home electricity) and the total length of wires is about 60 feet.

Following are the details:

Intercom Model: Panasonic VL-SW250BX Intercom Details

From main monitor to door station, required  DC voltage is 20V and current is 190ma and (5V DC, 2 mA standby) according to the door station back label image Door-station-back-label

Recommended wiring by the manufacturer: CAT3 24Awg with maximum length of 350 feet

My wiring setup: Un-twisted 4 parallel individual copper wires (normally used for home
electricity)

I would like to know if my system will using these wires or if I need to change my wiring.

Update Just for information: I took the risk of installation and fortunately the system worked with a little noise in picture.
I will follow  W5VO advice to put some ferrites around the power wires near the intercom
Thanks a lot for the help


texts:
I have been trying to construct my own noise-canceling headphones. I have tried 2 different circuits and even combined the 2 with my own knowledge of analog electronics. Please see the links below if you would like to see the full description of the product.

The one on Instructables uses a phase delay using an all-pass filter, and an inverting summing amplifier at the end, I have done many variations to the all-pass filter with no luck on any noise reduction. see an image of circuit below:

The second one makes use of a 180-degree phase inversion, it doesn't have an effect on noise reduction it just amplifies the noise, see an image below.

I have tested the circuits with a single sine wave and all the components function as it should and the microphones work, I have tested everything using an oscilloscope but still no luck.

Could you please give me some advice on what to look out for or what could possibly be the reason so that I can investigate this issue.

link 1 : https://www.instructables.com/id/Analog-Noise-Cancelling-Headphones/

link 2 : http://www4.ncsu.edu/~rsmith/MA574_S15/silence.pdf


texts: Calculation of resistor values which control LEDs through transistors and have pull-up / pull-down resistors attached

texts:
During startup of ESP8266:

GPIO15 needs to be LOW
GPIO2 needs to be HIGH

I want to be able to turn on/off RGB LEDs connected to GPIO2, GPIO15 and GPIO4 via MMBT2222ALT1G NPN transistors.

Data:

Red: Uf = 2 V
Green: Uf = 2.5 V
Blue: Uf = 3.3 V
If = 22 mA
VCC = 3.3 V
hFE = 10 (?)
Vbe = 0.82 V (?)
Vce = 0.3V (?)

Schematic:

I'm lost in my calculations of R2, R21 and R22. Some time ago I calculated them as follows on the schematic and the device was working properly but I guess I was just lucky.

So how should I calculate them properly?


texts:
Following the failure of my first board design, I designed the following STM32F103C8T6 board. I only routed the fundamental parts of the board(MCU,caps, crystal, regulator etc.)

This is a 2-layer board with top layer being GND+signal and bottom layer being VDD+signal. Caps and resistors are all 0805 package.

My question here is, is there anything wrong with this design? Are there any flaws? I placed some of the decoupling caps under the board, otherwise I found it impossible to route some tracks. I'd also be glad to hear general opinions about the design.


texts: Battery to AC conversion voltage question

texts:
I am converting a device that uses 2 [C] size batteries (1.5V) to use a transformer in an AC outlet. I understand that the transformer rating should output 3 volts.

However.... I only found a 3.2 volt output transformer in my stash. Can I get away safely with using the 3.2 volt transformer in this instance if it's all that I have and don't want to buy one?

Thanks in advance.


texts: Is it possible to charge a lead acid battery(12V) with float voltage(13.6V) instead of charge voltage(14.4V)?I understand it will take lot of time to charge if we charge with float voltage.


texts:
I'm building an electronic DC load. I'd like to implement voltage sensing (4-wire sensing). I made this schematic:

Input voltage can be up to 60V, this circuit basically divides it by 6, and output voltages go to various parts of DC load (ADC, analog multiplier, opamps, etc.). It is not just about ADC, I need analog value of that voltage (so it is not possible to use 2-channel ADC and measure both inputs in software).
When SENSE+ and SENSE- are not connected, voltage is automatically measured at LOAD+ and LOAD- terminals.
When SENSE+ and SENSE- are connected, voltage is automatically measured at SENSE+ and SENSE- terminals.

My question is whether this implementation is OK, or there could be some potential problems, or is there a better way of doing it?

Another way I can think of is to use relay, second MAX44241, and switch relay manually in software/MCU. But I prefer "automatic switching".

EDIT:
I goofed up that opamp stage. I definitely should use instrumentation amplifier:


texts:
I am embarrassed to say I have been wrestling with this problem for some time, and am near to giving up. My TIA PCB always outputs high. The bread board version works well enough, albeit with slightly different components. The current schematic looks like:

The opamp is a LMH6629, all of the resistors and caps are 0805. The PCB for this looks like:

I have tested each of the lines, and so far as I can tell, they have the voltage I would expect (excluding the output). I have checked for shorts for days now. I can't seem to figure out the cause. Any trouble shooting or design advice would be helpful.


texts:
As you know, H-bridge circuits are used in order to control DC motors.

Switches S1-S4 are closed to turn the motor in one direction, S2-S3 are closed for another. But at the time of changing motor direction, when switches (transistors) are opened, Back EMF kicks in and makes the switches blow up. That's the reason of using diodes parallel to switches (See figure below).

On the other hand, these diodes consume significant amount of power. I am currently trying to solve this problem, and make a "diodeless" H-bridge circuit work.

I am using an mCU to control the motor with PWM signals. Is it possible to make a flawless timing for switches to not blow up?

For example, on the schematic above, assume that the situation is as this: S1 and S4 are closed and motor turns in that direction. When I want to change the direction, I open S1-S4; and close S2-S3. By this, I have burnt the switches several times. Now, my idea here is to open S1, and close S3 for a while. By this, I think I'll be able to let the remaining current be absorbed (on the circuit S3-Motor-S4). Then, I open S4 and close S2, which reverses the direction of the motor. As I said above, I am not sure about that if it is possible with an mCU. Also, I would need to analyze the characteristics of the motor and switches in order to find the perfect timing for the algortihm.

What do you think about this idea? Is there any method that you know or can suggest to overcome this power consumption issue? I have searched online but couldn't find anything.


texts: Measure capacitance with OPA604 and this circuit

texts:
I am following this circuit:

 to measure the capacitance. The opamp is OPA604 with supply voltage +-5V, Cx and Cf is 5pF, Rf is 10Mohm, the diode is 1N4007 and the output capacitor is 1nF. I also have 3 CD4051AN analog multiplexer/demultiplexer at 2 sides of Cx to change the capacitors and between the diode and the output capacitor to discharge the output capacitor. Then I connect Vi to about 100kHz sine wave signal.

The signal at the output of op-amp seem to have a low frequency noise, which makes the whole output seemed to be moving up and down:

And the signal after the diode still have the sinewave there, which I cannot understand.

Then I tried changing the 10M resistor by a 636k resistor, and the low frequency noise at the op-amp output just disappeared. The signal between the diode and the output capacitor also seemed to be much more constant.

So could anyone please explain to me where is the low frequency noise come from? And also how can there is a sine wave between the diode and the capacitor (since the diode forbid any discharge to the capacitor). Any pointing is also greatly appreciated. Thanks in advance.


texts: How does the compensation resistor in an inverting amplifier compensate for the input bias current?

texts:
I can't see how a resistor placed on a whole other input terminal has anything to do with compensating this input bias. i.e. the input stages are just the gates of transistors of differential stage. In this circuit, one of them is completely connected to ground and has no current to flow FROM or TO the op-amp.
This is saying that the non-inverting transistor has a current flowing from its collector to its gate. (At least the way I understand it.)

The most common compensation involves adding a resistor [R3] to the standard inverting amplifier to cancel out bias currents [output offset].
The compensation resistor [R3] causes a current, on the positive terminal, equal and opposite to current flowing into the negative terminal.
So any DC output offset caused by the inverting input is cancelled by the non-inverting input.
The value of R3 should be equal to the parallel combination of R1 [Ri] and R2 [Rf].


texts: Ideas for what to use as project enclosures/cases

texts:
I have seen myself working on a growing number of projects over the past few months. The one thing I have started to dislike is seeing the circuit board (and often my messy soldering) after I consider my project complete.

I would like to start putting my projects inside small project boxes/enclosures, but have noticed that items dedicated for this purpose are often overpriced for just a plastic box. I was wondering if people here had any tips with regards to what they use to encase their finished work. I am open to constructing simple boxes as well, which have the added advantage of being customizable. Any tips there would be appreciated as well (i.e. what material you use, overview of construction method, etc.)


texts: Best way to connect coax along a microstrip

texts:
I have an open-ended (stripped, if needed) coaxial cable that I would like to use to insert a signal into a microstrip.
The circuit (operating at ca. 18 GHz) however, is made in a way where I can't connect the coax to the end of the microstrip like one would usually do but instead the signal will have to be inserted somewhere along the line.
What is the best (=best coupling to the circuit) way I can make the connection in this situation? I know that one way would be to just solder the stripped end to the top of the microstrip but is that really the most efficient way of doing it or just an simple way?


texts:
I am stydying control systems, and I am trying to understand better the topic of causality.

I know that a system is causal if the actual state depends only on the past states and on the present state, so I can represent a causal system for example as:

\$y(5)=x(4)\$

And also I could represent a transfer function of a causal system as for example:

\$\frac{1}{s+1}e^{-s}\$

which has as step response:

which is not related to the previous example in state space, but I wrote this just as an example.

Now, I would like to understand better the behavior of a non-causal system. As far as I know, a non-causal system is not realizable, since it is a system in which the actual state depends on the future states, and this is impossible.

But I can't understand well this concept of non causality. For example what is an example of transfer function of a non causal system and its step response or frequency response?


texts: Storing value of a conditional assignment in Verilog

texts:
Assume I have the follow assignment

wire COND;
assign COND = A & B;

The values of A and B are changing between true and false, however, once they both hit 1 at the same time and COND = 1; I wish to keep this COND as a true value (sort of like a trigger) instead of it reverting to 0 when A and B changes.

Does anyone know a neat way to accomplish this?
Thank you!


texts:
simulate this circuit – Schematic created using CircuitLab

I've tried to Google it but my keywords don't really yeild anything.

I'd like to read more about this type circuit ; what applications its useful in ? How to select C1 ?  From what I recall, it provides a DC gain of 1, but provides an AC gain set by the feedback resistors.

Does it have a name ?

Added
I should have emphasized that the focus for this question is C1 and its location in the circuit.


texts: Vitesse VSC8221 Ethernet PHY for Media Converter Application

texts:
I'm currently designing a media converter board using Vitesse VSC8221. Just as an FYI, the documents for this product are all available at the product page. No NDA is required.

When I say media converter, I actually meant SFP interface for fiber medium to RJ45-CAT5 for copper medium, and vice versa.

Now, I've studied the datasheet and application notes of the chip quite extensively, and the chip does offer a 'Media Converter' mode (Datasheet:Section 4.2:Page 2). The application diagram for this mode is as shown below.

While I can use this mode, one drawback of this mode is that it only supports 1000BASE-T to 1000BASE-X. It doesn't support conversion to/from 10/100BASE-TX.

But in the datasheet, it's also showing a mode where it supports all 10/100/1000BASE-T to GBIC/SFP interface. The application diagram is as shown below.

Now, my questions are:
Can I use the second mode to do my media conversion? I know there are copper SFP also, but since the interface is specified as SFP, what's stopping me from using an optical transceiver SFP? If the Fiber-SFP(eg to MAC) can transfer data both ways, why can't I simply put my optical module at the SFP signal pins and get it to work as optical-copper converter instead?

If no, does this chip allow me to do a one-chip media conversion that supports all 10/100/1000BASE-T, even if that means I can't use the 'Media Converter' mode? I've read the datasheet and I'm still not sure of the answer.

I hope someone can offer some advice on the matter. Thank you so much in advance.


texts:
It is an edge triggered D flip flop where X is input, Y is clock, Q is output.
Is this D Flip Flop positive edge triggered or negative edge triggered?
ADD (copied from a comment): Actually I am trying to learn digital circuits. While trying to do so I got stuck in this question. I know the answer of it (it is a positive edge level triggered D Flip Flop) but I cannot understand how can somebody deduce it from this figure.


texts: Can the the rate of the flow of electrons (current) remain the same even though the number of coulombs differ?

texts:
I understand the concept of a current, and how current is defined by the amount of coulombs passing through a point in the circuit, per second.

What I'm confused about is when it comes to parallel circuits, and how currents are not constant.

If current is the rate of which charge flows, do speeds of the electrons matter on how many they are. For example, can't a group of 0.5 coulombs of charge flow as fast a 1 coulomb of charge? Why is current dependent on the number of coulombs? It's kinda like a drop of water running down a pipe as fast as a stream of water. So what really is current....?

And since voltage is proportional to current, does that mean it is also proportional to charge (amount of coulombs). So a higher value of coulombs will result in a higher value of voltage...?

Apologies in advance if I sound like a neanderthal.


texts: In Altium Designer, use only part of an harness

texts:
I would like to create harnesses with only some signals used, not all of them. for example:

However, even with this harness definition:
  SPI=SDO,SDI,SCK,SS0,SS1,
I still get an error: Conflicting Harness Definition for SPI

Can I get the harness in the image to work? How should I configure Altium to do that?


texts: what IC´s can duplicate an analog signal?

texts: currently i´m duplicating an analog signal with a dual buffer with op amps, i have to duplicate 8 signals... is there any IC that has IN, OUT1, OUT2?


texts: Can bright LEDs cause eye damage even if they are dimmed with PWM?

texts:
I have an extremely bright LED, so bright that I wouldn't want to look at it when it's at full brightness.  I am dimming it with PWM (pulse-width modulation) down to 1/256 of its original brightness.  At a 1/256 duty cycle, the LED appears reasonably dim.  (Still quite visible, but not blindingly bright.)

My question is this: since the LED is actually sending out super-bright pulses 1/256 of the time, can these bright pulses hurt the eye more than a hypothetical LED which was on constantly and was 1/256 as bright?

I'm using the TLC5947 LED driver, so if my calculations are correct, the frequency of the PWM is approximately 1 kHz.  (The chip's internal clock is 4 MHz, and one PWM cycle is 4096 internal clock cycles long.)

The LED I'm driving is this RGB 7-segment display.  The brightness of each segment is 244 mcd for red, 552 mcd for green, and 100 mcd for blue.  So with all 7 segments illuminated, it would be 7 times that.


texts: How to estimate the temperature of a filament?

texts:
I would like to know how I can estimate/calculate the temperature of a heated filament.
For example, the filament (rhenium) is 0.2mm in diameter and heated with a voltage of 6.4V and a current of 2.72A (i.e. power=17.4W.)
My second question: How does the temperature of the filament depend on the filament current?


texts: Non-linear torque vs speed response for DC motor

texts:
I have a Faulhaber DC motor (model 1524T012SR) that I coupled to a cheap DC motor in order to characterize the cheap motor to use as a generator (and get RPM and torque from voltage and current). The Faulhaber motor uses a motion controller (MCDC 3006S) that was purchased with the motor years ago. I am using the motion controller to step through various motor speeds from 1000 to 9000 RPM.

I expected the current output from the Faulhaber motor to be linear for a linear change in speed but it is not. The current increases until about 2500 RPM and then starts to drop as the RPM increases, similar to a stepper motor response. The problem that I have is that the datasheet provided with the motor only gives a single torque constant (11.5 mN-m/A) so I have no idea how to get the actual torque supplied to the coupled motor.

Is this a problem caused by using the speed controller for the Faulhaber motor? What can I do to determine the actual torque output by the Faulhaber motor?

Here is my setup:

Here is the current drawn by the driving motor for a linear increase in speed: (it says torque but it's just the current times Kt.)


texts: Why aren't V-NAND capacities 8 times greater than ordinary NAND?

texts:
The question is about NAND flash chips used in all kinds of electronic devices and specifically the recent V-NAND chips. You can see what V-NAND is from http://en.wikipedia.org/wiki/Flash_memory#Vertical_NAND. The idea is that NAND flash cells are stacked on top of each other to increase areal capacities.

Now, Samsung has 32-layer V-NAND chips. According to my understanding, these chips should have 32 times greater capacities than ordinary NAND chips if manufactured using the same process node. True, the V-NAND chips are manufactured by using a bit older process node than the state of the art. According to http://www.extremetech.com/computing/194911-intel-announces-32-layer-3d-nand-chips-plans-for-larger-than-10tb-ssds, Samsung uses 40nm process node for V-NAND, whereas Samsung's state-of-the-art ordinary NAND chips are manufactured using the 19nm process node.

Even taking this into account, 32*(19 nm/40 nm)^2 is approximately 8. Thus, we should have 8 times greater capacities for V-NAND than for ordinary NAND. Considering that one can obtain 1-terabyte SSDs that contain traditional NAND chips, why can't one find any 8-terabyte SSDs that contain V-NAND chips? And similarly, why haven't smartphone and tablet memory sizes become 8 times greater after V-NAND was invented?


texts: How can I transform this circuit so that the output voltage not depending on the supply voltage of the amplifier(V2 and V1)?

texts: I have to modify this circuit so that the amplitude of the output signal be the same,everytime I change the value of V2 and V1...How can I do that?


texts:
According to Wikipedia:

  GMII [...] is backwards compatible with the media-independent interface (MII)

But is RGMII backwards compatible with RMII?

I'm asking this because I'm making a schematic of an iMX6 System on Module. I have the RGMII pins, I only want a 100/10 interface, I found some RGMII interface (for gigabit ethernet), and some RMII and MII interfaces (for 10/100).


texts:
In ARM,

Data-processing instructions have an unusual immediate representation involving an 8-bit unsigned immediate, imm8, and a 4-bit rotation, rot. imm8 is rotated right by 2 × rot to create a 32-bit constant.

Here is an example. I just can't figure out how it is that...


texts:
Just looking to have two devices on a single bus with the same address. There are many I2C multiplexers available, but they seem to cost ~4x what a 2x 2:1 analog multiplexer costs.

Any reason I can't use an analog multiplexer for I2C running a 100kHz bus?

For example a TI TS3A5223RSWR is 0.63 cents, and based on the data sheet, supports bi-directional analog signals with a small ~1 Ohm impedance.


texts: AND Gate Not Working Properly in Combinational Circuit

texts:
I'm designing an arithmetic circuit that takes in two one-bit binary numbers as input and outputs the result with LEDs representing 1's and 0's for each digit. OUT1 represents the state of the first digit, whereas OUT2 represents the state of the second digit.

The circuit for the first digit is working properly. If I switch IN2 (the first number) to 1, OUT1 lights up, as it should. I have not yet completed the second piece of that circuit that will set light up OUT1 should IN1 be 1 and IN2 be 0, that will come after this problem is solved.

The problem lies in OUT2. When I simulate in Multisim, if both IN1 and IN2 are switched on, OUT1 should turn off (which it does) and OUT2 should turn on (which it does not). I don't understand why it wouldn't be turning on, as I have what I believe to be a direct AND gate leading to OUT2.

A picture of my circuit is shown below, any help with this would be greatly appreciated.


texts: Are too high capacitance capacitors "bad" for the circuit?

texts:
I am trying to learn basic circuitry and I've been looking into capacitors and their uses in different areas.

When looking at capacitance several different sources say that circuits might malfunction or burn with higher capacity capacitors than designed with. Unfortunately, but none of those sources go into detail.

How can a capacitor cause malfunction if capacitance increases? Wouldn't the capacitor simply take longer to fully charge?
Can high capacitance capacitor really cause any sort of "burn"? I mean it cannot store or produce higher current than what is given by power supply, right?

Am I missing some important detail?


texts: Is it theoretically possible to be killed with coin cell batteries?

texts: Other than the obvious eating them, is it possible to squeeze enough electricity out of a coin cell battery to cause harm? Maybe using a boost converter with a large capacitor? Or maybe using a bunch of them in series?


texts:
It's my first time making a PCB. I've got pretty far with all the YouTube tutorials however I'm now stuck on what to do next. My PCB is going to be made up of WS2812B chips (4 pin LEDs comprising VDD, GND, data in and data out).

I want to be able to daisy chain the PCBs with solid core wire however I'm not sure how to put the appropriate connection on the board in KiCad. At one end of the PCB I'll have VDD, GND and data in. At the other end of the PCB I'll have VDD, GND and data out.

What's the best way to put this onto a PCB? Presumably I'll have to edit the schematic in some way? At the moment, the first and last WS2812B chip have their respective data in and data out pins disconnected.


texts: MAX10 Flash and separating NIOS Firmware from FPGA config for remote updates

texts:
I'm trying to get to grips with how MAX10 memories work, especially if you want to split firmware and FPGA config into completely separate sections. I have read and reread the MAX memory guide, but I'm unclear about several things.
Although Altera/Intel call memories UFM for user flash memory (for firmware and/or user data)  and CFM for configuration flash memory (for FPGA configuration), it seems they are loose terms and that you can store firmware in the CFM.
In our case there is a desire to split the FPGA and NIOS firmware so that it's possible to upgrade NIOS firmware and the FPGA config separately. The FPGA config is largely stable and most of the changes now will be to the firmware that the NIOS processor runs.
So, the first question is: is this even possible? Do you have to update both the FPGA config and the NIOS code together?
If it is possible, how would/could this work?
Could we:
Have a never-to-be-changed image (I think that's what people refer to as a golden image) in CFM0 that comprised of a simple NIOS core and its firmware that downloads new firmware images into UFM0 and UFM1 and/or FPGA config into CFM1 and 2? Or can a firmware image only fit in either UFM0 or UFM1?
One thing that concerns me is that the NIOS projects seem to be very bloaty. Even a simple hello world program takes up 24k program memory from what I can make out. If that's the case we're soon going to run out of UFM space if you can only use a single 32k block per program. This would suggest you're better off keeping the NIOS code in with the FPGA config and storing it in CFM, but that might mean you can't upgrade firmware separately to config data.
Which leads me on to external flash. In the documentation it suggests using external flash for the firmware if the program is going to grow too big. It has been suggested to me that the MAX10 only works with certain flash chips for booting, and if that's the case (I can't find anything to confirm or deny this), would we possibly be painting ourselves into a corner when a flash chip is made obsolete (which they regularly are). I appreciate there may be Altera-specific config devices that they'd keep going for the life of MAX10s, but then would you be able to store extra user data in those that could be pulled out by firmware the NIOS processor runs in normal operation?


texts: Lowering various input voltages by 1 volt

texts: Step-down buck converters like this one lowers various input voltages to a fixed voltage. For example 12V/9V/6V to 3V. But is there way to lower various input voltages by 1 volt, that is, 12V to 11V, 9V to 8V, and 6V to 5V?


texts: How to prevent applying power to I/O pins before BBB ready?

texts:
From the Beaglebone Black SRM Rev C.1: "DO NOT APPLY VOLTAGE TO ANY I/O PIN WHEN POWER IS NOT SUPPLIED TO THE BOARD. IT WILL DAMAGE THE PROCESSOR AND VOID THE WARRANTY.
NO PINS ARE TO BE DRIVEN UNTIL AFTER THE SYS_RESET LINE GOES HIGH."

I want to connect a sensor to ADC input. When I apply the power to BBB and to the sensor in the same moment, there is a danger that the signal from sensor comes earlier as BBB is ready. What is the best way how to prevent from this?

I can imagine following:

a) Control a transistor with SYS_RESET signal to switch on the power for the sensor?
b) put "something" between the pin and the sensor?


texts:
I am using the following code to create an array of pin to use in my Arduino sketch:

int LEDS[] = {7, 8, 9, 10};
int wait = 100;
int pinCount = 10;

void setup(){
  for(int PIN=7; PIN < pinCount; PIN++){
    pinMode(PIN, OUTPUT);
  }

  Serial.begin(9600);
  Serial.print("First LED: ");
  Serial.println(LEDS[0]);

  Serial.print("LED Array Size: ");
  Serial.println(sizeof(LEDS));

  for(int i=0; i < sizeof(LEDS); i++){
    Serial.print("Testing Array Index[");
    Serial.print(i);
    Serial.print("] with value: ");
    Serial.print(LEDS[i]);
    Serial.println('***********);
  }
}

It seems to me to be quite simple but I get a value twice the actual size of my array and the data in the indexes are not intelligible. Below is sample output:

First LED: 7
LED Array Size: 8
Testing Array Index[0] with value: 710794
Testing Array Index[1] with value: 810794
Testing Array Index[2] with value: 910794
Testing Array Index[3] with value: 1010794
Testing Array Index[4] with value: 10010794
Testing Array Index[5] with value: 1010794
Testing Array Index[6] with value: 010794
Testing Array Index[7] with value: 010794

Can anyone please assist and help me get the correct number of indexes and the data, please?


texts: Malformed relay? Outputs current from NO when no signal is passed

texts:
I'm using this (SLA-05VDC-SL-C) relay.
After about 40 minutes of usage (with this module) at ~10A turing the relay off via the module seems to turn it off (click is sound and the red light turns off) but, the NO leg still outputs current at ~196V when the input is ~230V (NC is obviously ~230V).
Only after 1-2 days the NO stops outputting any current.

Is the relay malformed?
No reason for it to behave this way right?
How can I check it further and maybe fix it?


texts: Why Vi(on) minimum values is higher than the typical value of PDTC124E (NPN transistor)?

texts:
Please see the datasheet of PDTC124E (NPN transistor) for reference.

I have added the snapshot of relevant section for quick reference.

Snapshot

Here the Vi(on) value for the transistor is 2.5V and 1.7V are minimum and typical values respectively.

Please explain why typical value is less than the minimum value.

I am a beginner in analog filed. Apologies in advance if the question is very basic.

Thanks,

VT


texts:
Good morning I have been asked the question to name as many losses as you can in a DC shunt motor and state weather these will increase or decrease with increased load.

Now I have had a look at various books and websites but I can't seen to find what I am looking for. I have identified the various losses but am unsure of where to look to see if they increase or decrease or  remain constant when load is increased.

Heres my shot at it anyway

Increase= Energy loss, copper loss, core loss, mechanical loss, (windage)
Decrease= Brush losses
Constant= Magnetic losses, (hysterisis, Eddy current) Stray losses

Can anybody offer any comment on these might be completely wrong?

Thanks Jamie


texts: PWM equivalent for a constant current source and load

texts:
I am working with LED drivers and compatible LED lights. They look somewhat like this:

These come in two versions: (1) Constant voltage type and (2) Constant current type

I am implementing a circuit which is able to dim the light. It involves a mosfet switch which sits between the driver and the LED.

For the driver which outputs constant voltage, the circuit works fine. I am able to vary the brightness of the LED by varying the duty cycle of my PWM signal.

However it doesn't work for the driver which outputs a constant current.

What would be the equivalent method for dimming the LEDs in case of a constant current source?


texts: What does a parenthesized current rating on a switch mean?

texts:
I'm speccing out some switches for a project... is this some standard notation I've never seen before?

Electrical Ratings: 12(4)A 250V AC

What does the (4) mean?

(Source)


texts: What is meant by "carry Bit from Previous addition" in Full Adder?

texts:
A full adder is a combinational circuit that performs the arithmetic sum of three bits: A, B
and a carry in, C, from a previous addition
Q) What is the meaning of this bold text? (i.e from a previous addition)
I know what a carry bit is, but when it comes to Full Adder I get confused by this statement...


texts: Can I use SPI for asynchronous serial output?

texts:
I need a second serial async output channel on the MSP430G2553 and would like to use the SPI USCI to do this.

Is the USCI SPI baud rate stable enough to do this at 300 baud, 2400 baud or 9600 baud? I am currently using the 8 MHz clock.

Is there any other option that can save me from bit-banging?

My current thinking for 300 bd Tx is as follows:

set prescaler to 26666 LSB first
load byte into Txbuf
load 0x7F into Txbuf to generate stop and start bits
repeat 2-3
send final stop bits 0xFF

It might also be possible to send ten bits of data on other members of the MSP430 family that contains a SPI.

Thanks for your responses.


texts:
I've designed some PCBs where I have a socket for a Teensy 3.2. The exact sockets I purchased were these turned pin open frame sockets. I also purchased these turned pin headers to solder to the Teensy.

This works great, however the Teensy is really hard to remove without bending the header pins. Obviously a certain amount of force is required to remove the Teensy. Are there any tools that would help or a particular recommended method?


texts: Adjustable Voltage Regulator Resistor Values

texts:
I'm working with an adjustable voltage regulator and am having a hard time understanding my equation for determining resistor values.

Datasheet: http://www.chinaeds.com/zl/20103612559506780_AS2850YU-X,AS2850YT-X,AS2850AUPDF.pdf

I'm able to get ~5V (my goal) on Vout when using the following values:

Vin = 12V
R1 = 22K
R2 = 1.47K (1K and 470 in series)

As soon as I put a load on Vout it drops to ~3.7V

What am I doing wrong?

Edit: turns out I had multiple regulators that were bad. Once I found a good one everything works as expected (with the proper resistance values).


texts:
I have a nokia phone charger which has the following specifications:

Input: AC 100-240 V, 50-60 Hz, 100 mA
Output: DC 5.0 V, 350 mA

When I checked the output of the charger with a multimeter it shows 7.7 V. Why is it so? Is it because the charger voltage should be greater than battery voltage (for powering the load and charging battery) or any other reasons?


texts: What should I expect the output of my line scanner to look like on an oscilloscope?

texts:
I'm trying to test my TSL1401R-LF line scan camera module by checking the reading on an oscilloscope. I've confirmed that my SI and CLK signal are running normally but the output looks very strange to me. I expected the output to be a set of square waves the represented the pixels being outputted but isntead I just see a really shaky line.

Here is a screenshot:

The purple line at the bottom is the output and even when I free a frame I get different looking lines. I'm not sure if this is normal or if I'm doing something wrong. Can anyone make sense of this?


texts:
All units are in the SI

I'm doing my task from vacuum electronics - for the given klystron with a toroidal resonator[

Resonator:

I have to find the $h$ parameter, that will satisfy given conditions:

$$f=10GHz$$

$$U_{resonator}=250V$$

$$electrons\space stream\space diameter\space 2a=6 mm=0,006 m$$

that can be found from the given toroidal resonator eigenfrequency formula, considering, $$b=2a$$ and \$c\$, as far, as I understand equals \$0,73\$:
$$f_{\text{res}}=\frac{c}{\pi a \sqrt{\frac{2 h}{d} \ln \frac{b}{a}}}$$

\$d\$ can be found from the next equation, considering \$\theta=0,75\pi\$

$$\theta_{i}=\omega \tau=2 \pi f\left(d / v_{0}\right) \quad v_{0}=5,93 \times 10^{5} \sqrt{U_{\text{res}}}=9376153,262\space mps$$

When I put all this stuff in one, I got

$$d=v_0\dfrac{0,75\pi}{2\pi f}=\dfrac{0,75*3,14*9376153,262
}{2*3,14*10000000000}=0,000351606\space m$$ that seems correct

$$h=\dfrac{\dfrac{d(\dfrac{c}{f\pi 0,003})^2}{ln2}}{2}=\dfrac{\dfrac{0,000351606(\dfrac{0,73}{10000000000*3,14*0,003})^2}{ln2}}{2}=1,5*10^{-20}\space m$$ that is obviously wrong

If I put \$d\$ and \$h\$ in $$f_{\text{res}}=\frac{c}{\pi a \sqrt{\frac{2 h}{d} \ln \frac{b}{a}}}$$, I get 10000000000, that means, that I've calculated everything correctly.

I've been checking all steps, all formulas, maybe I had missed something, but no, seems that the problem is in resonator frequency formula - it's wrong. I've tried to find it in the internet but get failed.

Please, provide a specified toroidal resonator frequency formula, or, if the formula, given in my task correct, point me, where am I wrong.


texts: controlling a 8051 microcontroller through bluetooth

texts:
My teacher wants to add Bluetooth communication to the electronic project in are school. He asked me to check out the possibility.

I tried googling, but I couldn't find anything I was sure about.

I am looking for a chip that fulfils the following conditions:

Decodes and encodes bluetooth communication.
Interfaced using RS-232 (anything else is acceptable, if you explain or give references for how to use it).
Nothing too fancy.

It could be more than one chip.
bonus: A full data sheet of the chip.

The microprocessor we are using is AT89C5131.


texts: I am wondering about the relative between Step input and bandwidth

texts:
How we can do define the explanation of bandwidth in step input graph?
Sorry to not explain about problem deeply, cuz I am newbie about control theory.
in book , that explaining smaller 3dB of when frequency =0
but i cant understand where is frequncy on the step input graph.


texts: what are the advantages of connecting two GND polygons only in one place on PCB?

texts:
Could you help me understand, why is connecting two polygons of the same net (for example GND) in just one place proposed?
What is difference if we connect pGND (power GND) and sGND (signal GND) with just one track on surface polygon and to make one solid polygon?
They are usualy connected to internal plane through via and they form one net.
Here is an example


texts: Best way to connect microcontroller, sensor and LED

texts:
I'm trying to read output from a sensor and at the same time drive some indicator LEDs. The 3 pins are configured as input on the MCU and output on the sensor. Both the MCU and the Sensor are at 3.3V. 100k resistor serves as a pull-down resistor and 220 ohms serves as a current limiting resistor. Am I doing this right? (See image)

Edit 1 :Minor correction on the image to connect the pull down for all lines as suggested


texts:
I would like to know why op-amps saturate below their supply voltage. For instance I have a circuit with an LM358-N amplifier IC that is powered at +5 [V] and connected to ground on the other rail. Theoretically the saturation should be 5 [V] but it saturates actually at 3.7 [V].

Why is this happening?
What is the term for this offset that I can find in the datasheet?
Are there op-amps that can go saturated all the way up to the supply voltage?

Thanks a lot!


texts: I am looking for a method to smooth a very sparsely sampled signal, which is shown below. Digital filters did not work very well, because for achieving an acceptable smoothness of the offset, the peak (which is very important) gets smoothed significantly as well. I've tried different methods: fit with stretched exponentials, fit with polynomial, wavelets. Applying a fit with two stretched exponentials has shown the best results, however I´m not quite there yet. Can someone point out other methods? Thanks!


texts: Is it Safe to Plug a Regular Power Strip (with no surge protection) into a Surge Protector Strip?

texts: When I did a Google search I found a lot of different answers, many of which contradicted each other. My understanding is that you shouldn't plug a surge protector strip into a surge protector strip BUT IT IS OKAY to plug a power strip into a surge protector strip (if you don't exceed the max power rating for the surge protector strip)?


texts: Equipment and approach for performing a long-term measurement of clock signals

texts:
This is a follow up question for the circuit I designed with the inspiration from here. The circuit works but over time there appears to be some clock jitter or skew. I am interested in an approach to perform a long-term measurement with a measurement period of at least 30min and then process the data with Matlab or Python, to see whats going on. I have never thought of how to perform a measurement like this and did not find anything useful with my google search.

The goal of the circuit is to multiply a 48kHz wordclock input to 12MHz clock for the Cool Audio V2902 codec Datasheet here.
The circuit was designed with the following components:

BNC Input with 75Ohm
Input Buffer: TI RC4558, Datasheet
Multiplicator: CS2300CP-CZ, Datasheet
A switch for choosing the internal crystal (moved from the Behringer PCB to my extension PCB) or the external source, Datasheet

Unfortunately, I have overseen that the RC4558 is specified for a supply voltage starting at 5V. My circuit works on 3.3V. I removed the IC and replaced the input and output solder pads with a wire. This leaves me with the following circuit (The RC4558 was originally placed between C1 and C2):

As already asked above: How can I measure the clock signal over a long time (at least 30 minutes) and then process the data. An initial idea was to use Matlab with a R&S HMO2024(Datasheet). More details about Matlab with the R&S oscilloscope here. Is this a meaningful approach and what other options are there?

UPDATE:

Thank you for all your comments on this project. Here is the current status of the project:

I use a Rohde&Schwarz HMO2024 with Matlab R2019 and the Instrument Control Toolbox. More details here.
The HMO driver from R&S is very easily installed on Windows 10. Not sure if there is a Linux/Mac OS version. There is this .zip file for Linux/Mac OS but I did not understand how to install the files it contained. Rohde & Schwarz HMO driver page here
The SCPI commands for the HMO Series can be found here

With some tests I found out that a data transmission usually takes around one second. This is fast enough for me. For initial testing I used the GUI and the help of this video.

clc;
close all;
%% Instrument Connection
% Find a serial port object.
obj1 = instrfind('Type', 'serial', 'Port', 'COM4', 'Tag', '');

% Create the serial port object if it does not exist
% otherwise use the object that was found.
if isempty(obj1)
    obj1 = serial('COM4');
else
    fclose(obj1);
    obj1 = obj1(1);
end
set(obj1, 'InputBufferSize', 500000);
% Connect to instrument object, obj1.
fopen(obj1);

%% Read identifier
%data1 = readData(obj1, "*IDN?");

%% Set start stop of measurement
% Number of measurements
measurementLength = 5;

%% Configure device
%Acquire mode to real time mode
writeData(obj1, "ACQ:MODE ETIM");

% Get samplerate
fs = str2double(readData(obj1,"ACQ:SRAT?"));
i = 1;

timestamp = zeros(measurementLength,6);

% First measurement
disp("Measurement: 1");
timestamp(1,:) = clock;
data_char = readData(obj1, "CHAN1:DATA?");
data = str2double(split(data_char,','));

% second measurement til end
for i=2:measurementLength
    disp("Measurement: " +num2str(i));
    timestamp(i,:) = clock;
    data_char = readData(obj1, "CHAN1:DATA?");
    data = [data str2double(split(data_char,','))];
end

readData.m

function data1 = readData(obj, command)
% Reads data from given object
fprintf(obj, char(command));
data1 = fscanf(obj);
end


texts: "Voltage divider holds 37% of supply voltage at negative" wrong in textbook

texts:
In my textbook, it states that "the voltage divider of R3:R4 holds 37% of the supply voltage at negative".
However, I think it should be 63%.


texts: Guitar amp "motorboating" after upgrading op amps

texts:
I've been repairing an old (~1982) Fender solid-state guitar amp. While I had it apart I took the opportunity to replace some of the RC4558 op amps with NE5532's in DIP sockets I installed.

It was working great (much quieter). I left it on the bench for a couple of weeks and today when I came back and switched it on, I got a loud low-frequency "motorboat" from the speaker.

So far it looks like the buffer amp at the output of the tone control stack is oscillating. It seems to come and go, with varying amplitude—sometimes it seems fine, sometimes it's a fairly low-level sine wave, and other times a clipped almost-square wave. Update: this is the op amp towards the upper right corner of the schematic, labeled "1/2 IC2". I notice that there don't seem to be any bypass capacitors on the supply leads, so adding some might help.

The only possible variable I can think of is temperature: my bench is in an unheated room and the weather has turned colder. Hardly seems likely, though.

Any ideas what could be causing this? When I read about op amps oscillating, it's normally at a high frequency, right? The amp's other, high-gain "lead" channel seems OK.


texts: Differential amplifier with differential output and common-mode shift

texts:
Summary: I would like to build a differential amplifier with differential output, but shift the common mode to a different level from the original.

My current knowledge takes me this far: Take the traditional 3-opamp instrumentation amplifier, like the one in this image:

Now if you take the left two opamps without the third, those already give you almost what I want, that is, amplify the differential input and give a differential output. The only problem is it preserves the common-mode of the input. Adding the 3rd opamp on the right, it is easy to shift the CM by biasing its ground (in fact this is what most single-chip instr. amplifiers do when they provide a Vbias pin), but the output of the circuit is now single-ended.

So what is the best way of keeping both the differential output and the CM-shift? One way is, I guess, to take only the left two opamps of the above instrumentation amplifier, and shift the ground of each separately.

Another option that comes to my mind is to take only the left two opamps again, and (using an example when I want to halve the CM) use twice the gain as needed, and then divide each output by 2.

Unfortunately both of these solutions require more (in quantity) highly matched resistors with low TCR (I'm trying to keep temperature drift of the circuit very low), and those are bloody expensive.

So how would you go about this problem? Maybe taking an instrumentation amplifier is the wrong start? Is one of my above solutions the "standard" way of doing this, or are there better circuits for this purpose?

EDIT: Clarification on matching resistors: What I mean is to match them in TCR, because I am aiming to minimize temperature drift. This means I need to match resistors in TCR, not in absolute value, so that when they drift due to temperature, they will keep their original ratios. Actually I am uninterested in matching absolute values (almost, I still need a little bit of matching to maintain CMRR), for two reasons: 1) a mismatch in absolute value causes offset and gain errors, both of which are easy to calibrate out at system level. Measuring and correcting temperature drift is a lot more difficult. 2) Most of the offset errors will be non-existent anyway without even calibrating, because this will be a frontend to a sensor, and offset errors will cancel out due to AC excitation of the sensor. Anyway: closely TCR-matched resistors are expensive (easily more expensive than precision opamps), so I want to minimize their use.


texts: How to get started with learning electronics?

texts: My main goal is to be skilled enough to design printed circuit boards to build devices like a basic smart watch and other simple projects. How do I get started ?


texts: Can an EPROM be "refreshed" without UV erasing?

texts:
I have lots of AM27C512 65k x 8b EPROMS (with the UV window) which are quite old (1980's.) Using a Xeltek SuperPro 3000U, most can still be read and verified. A few have failed outright and were replaced.

Question: Can these be successfully "refreshed" by reprogramming the same bit pattern back to them, without UV-clearing them first? They seem to take a reprogramming fine, but was curious whether this is moot without an erasure first.

Edit: Wanted to mention that so far, I've tried "refreshing" about 10 of these 256kB EPROMS. All of them read fine, were programmed (with the same data) fine, and verify fine. So "refreshing" hasn't seemed to hurt them at all. I'm still a little sketchy about whether this will make any lasting difference in their longevity however - answers are quite mixed.


texts: freechargecontroller.org. The blocking diode of the MOSFETS

texts:
I am looking at a schematic for a solar charge controller:
    http://freechargecontroller.org/images/a/ab/Charge_controller_4_04b.pdf

My question is about the MOSFETS M1 and M2. The data sheet for the MOSFETS I am attaching:
    http://www.jameco.com/Jameco/Products/ProdDS/669943IR.pdf

I think I understand that there is a blocking diode inside each MOSFET that allows for the flow of electrons from the source to the drain
but not in the reverse direction and that diode is called a body diode. It is shown in the data sheet for the MOSFET. I am looking at the way the
source pin of M2 is connected and it appears to me that what is connected to the source pin of M2 is a conduit that runs between that positive
terminal of the battery and the source pin of M2. There is an inductor coil on that conduit. Hopefully I will be corrected if this is not exactly the case.
It appears that J2-2 also ties into the same conduit and there is a blocking diode D3 in place there.

If the source pin of M2 then has a positive charge and there is a blocking diode inside M2 then wouldn't that blocking diode in M2 prevent the flow of electrons from
traveling from the drain of M2 onto the VS line when M1 and M2 are activated?

Also I think I understand that diode D2 and capacitor C2 are providing a bootstrap voltage but I'm not really sure yet how that bootstrap voltage is generated exactly or
what it is exactly used for. Could someone explain?

Thank You


texts: LM555 timers for control of a secure door

texts:
I will explain existing hardware followed by my desired operation thereof.

  I have a security door the controller of which has failed.
  The door has four electronic deadbolts.
    -- A) Two open when un-powered; close when powered AND door is closed (as determined by magnetic reed switch internal to these two deadbolts)
    -- B) Two open when unpowered and close when powered (with no internal sensors of door state)

There is a tactile switch with both NC and NO connectors inside to detect proper closure of the door which can be used.

My problem relates to the manual escape button found on the inside of the door. When pressed momentarily this should:
-- Un-Power the A deadbolts for 5 seconds; then power them again.
-- Power B deadbolts for 5 seconds and close ONLY IF tactile switches reveal that door is closed (otherwise the door would not be able to close against closed bolts)

I have this partially fixed by using one LM555 as a monostable timer unpowering A bolts for 5s and another LM555 as a bistable set to latch to powered state on button press. Both LM555's triggered simultaneously.

Problem is that after closing the door the B deadbolts do not re-latch without manual reset of the 2nd LM555.

My hope is that someone can advise as to how to develop an elegant solution to this problem which will allow:
--> Opening door for 5s on single button press
--> Automatic re-locking after 5s if door is again closed
--> Keeping door unlocked if not closed after 5s
--> Locking door again after door is closed (both before and after 5s has elapsed following button press).

I am sure this will be easy for someone experienced in the use of these timers.


texts: Can I use series diode to drop voltage from Lithium Ion battery to ESP8266?

texts:
Ideally I would use a low dropout regulator but I can't. I also don't have access to a suitable buck boost converter. The best alternative I have (and also my plan B) is to boost the Li-ion battery voltage to some 4.3V and then buck it down to 3V and power the ESP8266. I'd rather not do that.

This is what I want to do instead. I want to put a series diode (1n4007) between the battery and the device. I couldn't find information online that documents dropping voltage with diodes for dynamic loads. That's why I wanted to consult more experienced people before committing to it.

The worst case of fully charged battery and low forward voltage (4.2 - 0.6 = 3.6) is within specs of the esp module.
The average diode power drop (0.7V * 80mA = 0.05W ) is well below the maximum of the diode(3W).
The current draw of ESP8266 varies from a few uA in sleep mode to 500mA. Using the inbuilt ADC and some software, I can ensure that the ESP will not sleep when battery is fully charged to avoid less than 0.6V drop in the diode. For higher transient current draws, the diode might increase the forward voltage to 0.9V. I have kept the parallel capacitor hoping to smooth that transient voltage drop.

Even at a junction temperature of 100°C the forward voltage might drop by 100mV (Not in the datasheet, I'm using the rule of thumb mentioned in some article). It is still not difficult to make sure the voltage is still within specs.

So my question is, can I expect this setup to work reliably? I'm hoping for answers that correct my assumptions if they are false and point out flaws in this design.

This is the ESP8266 current consumption profile taken from this page posted for reference.


texts:
I'm having a hard time understanding these things.
Here's my situation:
I have 10 white LEDs. I bought them from China, and they have no rating and no one knows for sure their maximum voltage or amperage.
I'm using a 5V, 500mA power supply.
I first wired them in series of 2 and then in parallel (I hope I'm using at least partially the right terms), like this:

I didn't use any resistors because this should only apply 2.5 volts to each LED, and a white led is usually 3 to 4.5 volts? Right?
But the light was very dim, so I rewired everything in parallel and applied the full 5 volts to them.
Now I'm happy with the brightness, but the hot glue I used to attach them to the board melted.
So the question is, is the glue gun the wrong glue to use, or are they getting way too hot?
The amperage should be ok, 10 LEDs x 20mA should only draw 200mA, way below the 500mA the power supply can supply, or did I get this wrong too?


texts: Is there any way to have a diode that have very small resistance from reverse path?

texts:
I'm trying to find a way so I will always have close to 0V at the measurement point (above the diode), when I have 0V as input. The -3.3V is a fixed voltage source.
At 0.64V at input, I have -5.7mV at the measurement point. That's OK to me.
At 3.3V at input, I have 2.2V at the measurement point. That's OK to me.
But when I have 0V at input, then I have -271.2mV at the measurement point. That's to much negative!
If the diode have at least 10 Ohm in resistance, then the measurement point would be very close to zero. I what it to happen. But I cannot use a diode. Is there any better way to solve this issue without using a diode, or using a better diode?

Update:
Try this with a 3.6V zener diode. Change the current source from 4-20mA and look at the output. At 4mA, then we have close to zero volt. At 20mA, then we have about 2.2V. OK! But at 0mA, then we have -225mV. That's not OK! It should be low as zero volt as well.

Update:
Here is my solution. Is it good? At 4mA, we have some voltage for the ADC and therefore, we can see that there is a sensor connected.


texts: I would like to add an Hirose U.FL antenna connector to my PCB. I have no previous experience of using them, so I would like to now if I should connect both of the GND pins to the PCB ground or it's enough to connect one of them. I found  this PCB trace.


texts: I came across a DC-DC converter schematic and I notice that they use a bead on the schematic. I would like to know the purpose of this chip on this circuit and what the effect of removing it.


texts:
I am a newbie in electronics.

In my current project, I have to make two devices communicate with each other through UART.

One device (the HiKey board) uses 1.8v indicating signal '1'; while the other (the RK3288 board) uses 3.3v indicating signal '1'.

My questions are:

1. Can I direct connect the two UARTs?

2. What if the level signals of two UARTs mismatch?


texts: Can this comparator input exceed its supply voltage?

texts:
I will use this comparator with 12V DC single supply.

Some of the pulse inputs to this comparator will exceed 12V that is to say the inputs to its inverting input can be up to 24V. So input voltage will exceed the supply voltage.

So my question is:

Can I use this comparator safely when it is powered by 12V and the input to its inverting input is 24V?

EDIT:

I decided to use 8.2V Zener because the commentators said the common mode should not exceed Vcc-2V which is 10V in my case since I’m gonna use 12V single supply. But I don’t know which type suits good for this application where the inputs to the circuit(not the comparator input) will be between 12v and 24V pulses with max freq. 900Hz or so. Another thing is R5 is 1.5k. In average it dissipates 70mW but peak in simulation exceeds 250mW. Would that be an issue. The R5 is soldered so I don’t want to change it if not necessary.

Circuit basically:

Which zener type?:

Power dissipation of R5 for 24V input:


texts: State of charge estimation algorithms applicability to primary cells

texts:
Most references that I have seen refer to SoC estimation in a frame of electric vehicles.
My question is do these methods apply to primary cells? If so, do all these methods, and coulomb counting specifically, apply to primary cells?


texts: LEDs with built-in resistors vs 12v leds

texts: I've been researching this and cannot find any comprehensive guides. I'm looking to replace some incandescent bulbs soldered to pcb's inside my cars console. I've found some through-hole clear LEDs that have built-in resistors and they work but does that make them actually 12v? When I put a volt meter across the connections it reads the same output voltage as input voltage so I don't see the resistance happening. I've also looked for SMD leds with built-in resistors or 12v version but I don't think they exist. I don't really have room for resistors and looking for options.


texts: Supernodes with Constant Current & Voltage Sources: Voltage = Current

texts:
I am a technologist trying to improve my understanding of electricity by reading a textbook. I am reading Fundamentals of Electric Circuits and something that keeps popping up when solving the problems he proposes requires me to say voltage equals current. I cannot solve a few of his problems without dropping my units and just going with it so there is something fundamentally flawed with my understanding. Here is one example (there are a few going through chapter 3) (excerpt from PP 3.4).

The logic required to get one of his equations (according to the solutions manual I have) is that that the voltage across the constant current source of the supernode can be defined as V3 - V2 (that makes sense) but then he says this equals
\$5i (V3-V2 = 5i)\$.
He then solves for 5i (i = V1/R1) so V3-V2 = 5*(V1/R1). On the left hand side of the equation my units are voltage, and on the right hand side (according to ohms law) my units are current. This process of dropping units and just filling matrices seems to be prevalent throughout chapter three. Can someone please help me understand his logic? Should I find a new textbook or is there something fundamental I am missing? Thank you for your time and patience.


texts:
Battery cabling shall be sized as follows:
For a single plant: Battery cabling shall be sized to the greater of a 2-hour
discharge rate for ampacity or a 5-hour discharge rate for the voltage drop

Batteries: Deka AVR125-33

5 Hr. Discharge Rate: 352 Amps

2 Hr. Discharge Rate: 696 Amps

11.1=Constant for copper cable,
AVD=Allowable Voltage Drop,
LL=Loop Length,
CM=Circular Mills

Allowable Ampacity at 75 Degree C for 750MCM=475A

2 Hr. Calc=11.1*696A*40LL/.25AVD=1,236,096CM/750,000CM=1.64(2)750 MCM Cables per polarity

Voltage Drop=11.1*696A*40LL/1,500,000CM(2-750MCM Cables)=.21VD

5 Hr. Calc=11.1*352A*40LL/.25AVD=625,152/750,000CM=.83(1)750 MCM Cable per polarity

Voltage Drop=11.1*352A*40LL/750,000CM(1-750MCM Cable)=.21VD

What exactly do they mean by a 5-hour discharge rate for the voltage drop? I,m assuming I would go with the 2 Hr. choice since there would be more cabling involved. Will there ever be a situation that the 5 Hr. calculation will be greater? Since the amperage for a 5 Hr. discharge rate will always be lower than a 2 Hr.


texts:
I know that a crystal oscillator has a particular ageing curve, that shall be taken into account when designing a long-term application.

But what about the RC internal to the MCUs? I did not find data related to ageing, but only precision over temperature. I am speaking about Freescale/NXP 9s12g family because is what I am studying now, but this question is also more general.

Thanks.


texts: How do I determine the output voltage in this diode circuit schematic?

texts: What is the sketch of the output voltage (Vo) when the input voltage (Vi) is 5sin(t) V? Assume these are ideal diodes. I am confused because when Vi is 0V, the only 1V is dropped across the resistor due to the current source and there is 14V left.


texts: Mechanical relay circuit schematic and PCB. What is wrong here?

texts:
I built a relay that closes when a GPIO gives a GND signal.  I have tested the circuit with a breadboard and it works with the same components (except breadboard uses THD diode and PCB uses SMD), but for some reason my PCB circuit will not close the relay.  I am monitoring the normally open circuit by wiring in a 1000 ohm resistor and LED.  When the switch closes I should hear the mechanical relay and the LED should light up.  But no luck.
I do not see any differences between my schematic and PCB but something is off.  I even swapped out core components like optocouplers, transistors, relays to be sure they weren't just dead.  There is an LED which turns on when GND signal is given at GPIO, I can turn this on/off without problems so I know this signal is present.  I have verified that I am seeing 5V from my MOSFET power supply's drain, which supplies 5V to the circuit.  Does anyone know what could be keeping my PCB from working?


texts: Why are there types A and B in ISO 14443?

texts:
I'd like to understand why the ISO 14443 standard describes two types of interfaces, type A and type B.

This answer talks about competing technologies brought forward by two different companies: https://electronics.stackexchange.com/a/189164/103209. Can I find more details somewhere?

Thank you :)


texts: Can't identify this transformer [80LL 19T-6-L G HI POT LI - TAI B-19 0614 OK]

texts:
This is the power supply of my old lcd monitor, the transformer is burnt.

I have difficulties to find the correct model, I've googled about it without success (maybe I'm using the wrong keywords). The person at electronics shop told me that he can't identify the model.

Do you know this transformer? Where can I find the datasheet?

here the code that is print on it

 80LL 19T-6-L   G   HI POT
 LI TAI B-19   0614     OK

thanks


texts:
Do beam-forming devices expect a particular antenna configuration? For instance, do they expect the antennas to be a certain distance from one another? Or parallel to one another? Etc.
Background Info:
I have a beam-forming capable WiFi router located in a utility room. I would like to detach the antennas and add extender cables, so I can run them to various parts of the attic. I am concerned that whatever calculations are necessary to perform beam-forming may include hard-coded values based on the current configuration, e.g., each antenna is placed exactly 2 inches apart, and parallel to one another.


texts:
I'm trying to create a microphone array and take readings into a raspberry pi. I'm having an 8 bit ADC connected to the pi via I2C (SCL and SDA pins). I'm able to read samples (0-255) into my pi using this.

What I actually want to do is read input from 2 mics and find the cross correlation between the signals (to find direction of arrival of sound). Is an 8 bit ADC and I2C the right choice of tools for this? I would also want to do FFT on the signals.

If I'm using a 10-bit ADC, will I be able to plot an approximate waveform on my raspberry pi?


texts: The best components for a hybrid positioning system

texts:
I am stuck and need some extra brain power.

I am attempting to build a grid of sensors with a trackable object...constrained to an X-Y plane, AND the object that is being tracked must be done so wirelessly.

The grid is 2 ft by 2 ft and I need to have the smallest possible sensors in order to locate the object preferably within 1mm. Even if there are 1000 sensors on the 2 ft grid, as long as accuracy is present, that is all that matters. Sensors can and should be touching each other on the grid.
I will be viewing the grid on a basic computer monitor.

The object will be about the size of a quarter and will need a small transmitter that the sensors can read to show its location on the grid. I am not tracking speed or vertical distance...simply the location of the object on the grid...as close to real time as possible.

In a nutshell...I need to randomly toss the object onto the grid and see on the monitor exactly where the object lands.

I will be using the surrounding sensors for real time triangulation.
Any and all ideas for this are greatly appreciated!
Im even open to hybrid systems if necessary.


texts: What will happen when taps at secondary side of auto-transformer are connected together (short-circuited)?

texts:
In case of Auto-transformer, there is only one winding, having three lead wires (1 for primary/input, 1 for secondary/output, and 1 common between both). At the secondary side (the output side), there are taps (sort of voltage dividers).

I have a auto-transformer with input at 220 V, and i have taps at the secondary side at 200 V and 240 V (only mentioning my required taps, there are many).

My question is, what will happen if the taps at the secondary get short-circuited (200 V tap and 240 V tap gets short)?
What will be the effect of this incidence on primary voltage and secondary voltage?
Will transformer be okay? it won't get damage or something??


texts: Increasing Fall/Rise Times for Signal Integrity

texts:
I have a board that tests a wiring harness' continuity by outputting a set of test vectors onto the harness and reading it back. The wires in the harness can be as little as 1 m and as large as 10 m.

As far as I know, a termination scheme will not work for this because the characteristic impedance of the wiring harness isn't under my control. It will also change from harness to harness. So, my aim is to slow the rise/fall times of my signals for two reasons:

Improve signal integrity (I don't have any trouble with signal integrity so far)
My falling edge undershoots the baseline voltage by -2V. I fear this may damage my CPLD because the max. negative voltage allowable is just -0.5V (-2V is OK if the current is less than 100mA and if the duration is less than 50 ns according to datasheet).

Here's a picture of the falling edge:

This is with the following circuit:

In order to increase the fall time I increased R1 to 650 Ohms and it produced the following waveform:

]

My question is: Is my approach OK? Since termination isn't possible and I'd like to avoid damage to my device from signal undershoots and overshoots I felt it was best to slow down my fall times. I wanted to add, I have a LOT of time to sample the signal - as much as 800 uS before the signal rises again. You can see that here:


texts: Why is the current in the main circuit lower with Transistor vs without it?

texts:
I'm using EveryCircuit to start studying electronics and I have a question:

See image A and B. Why is the current in the A way lower than B? I was assuming it should be the same since the transistor is just switching it on.

I'm trying to make sense of this result.

thanks

A)

B)

Edit:

Answering  jsotola comment:

I guess you mean to invert the collector and emitter terminals, which I did and I get same results.


texts: Why Do Pin Numbers Sometimes Look Like Reference Designators?

texts: Sometimes when I look at schematics like the Beagleboard and the Raspberry Pi, some of the pin numbers look like reference designators, like C10. And what makes it even more confusing is that there is a capacitor named C10. Why would they do this for some components and not for others where they use regular numbers like simply 1,3, etc.? Why would they do this? Do they refer to them like,"the C10 pin" for pins and, "the capacitor at C10", or something similar to that? Is there any specific or special reason to do this?


texts:
I'm trying to convert mains AC to DC while dissipating as little heat as possible. Some ripple is tolerable if it cuts down on heat so I'm not sure if I need the regulator. I also don't know how well the values I've chosen for the various components will work together. Perhaps there's even a much easier way to go about it.

Finding parts is another concern. For instance, can a 22 volt regulator can even be bought?

Any helpful advice is greatly appreciated.

Here's the circuit diagram:


texts: current through the smoothing capacitor in bridge rectifier

texts:
Can any one tell the reason for the current through the smoothing capacitor to be pulsating in the full bridge rectifier.
I have attached the screenshots of the circuit and the wave form obtained in Multisim.


texts:
I tried google, youtube, stackexchange but couldn't find a proper answer.
I am trying to design a home automation system with arduino which need to control a fan and a light. Simply activating a relay with arduino is not a thing, but here is the problem. I am controlling the speed of the fan also. So here is the basic code structure would look like.

if pin 1 is high

[

identify the zero crossing point of ac source;

add some delay to regulate the output power;

pulse it to the triac;

activate the relay related to fan;

]

if pin 2 is high

[

activate the relay related to light;

]

When the pin 1 is high the loop starts running and it stays inside the loop until the pin 1 is low. then it looks for pin 2's status[high or low].
So question is how do i control the light while the fan is in on condition. A lot of forums are suggesting timers but none with this kind of situation. If possible please give a minimum code, so i can start from that. Thank you.


texts: How to predict KW rating and rated current when there is no nameplate on a three phase induction motor?

texts:
I came accross the following tasks during my trainee period in an electrical firm. I was provided motor with no nameplate in  following conditions:

When I can remove the mechanical load from the motor, so that i can run it on no load.

When i cant remove the mechanical load from the motor shaft. That is, i need to predict the Motor KW and current rating at loaded condition.

When the motor is defective, that is it is not starting( or i cant start it for some reason like overcurrent etc)

My questions are:

How to predict(calculate) the KW rating and current rating of motor in above three conditions?

If in any case i am unable to predict current rating then how do i know what size of Breaker and protection do i need for safe testing of that motor ?

Can i calculate the KW rating using physical size and parameters of a motor?

Umer.


texts: Safe to use series resistors for powering common anode RGB LED from single constant current source?

texts:
I have a 3-9W common anode RGB LED (https://cdn-shop.adafruit.com/product-files/2524/FD-9RGB-Y2.pdf) and want to vary each leg's voltage with PWM through FETs, namely IRLZ44Ns, and an Arduino, in a similar config to this: https://jasonwebb.io/wp-content/uploads/2010/12/schematic.png.
I am hoping to use a single current controlled source (https://www.ledsales.com.au/index.php?main_page=product_info&cPath=200_248&products_id=1508) and run each coloured element of the LED at 700mA by impedance matching each leg but am worried that the 2.1A from the source will just go through the path of least resistance when the source first powers on, and burn out the red LED. I was planning to limit the source to 5V (each element runs at below 4V) and calculated values of 2-5 ohms for each series resistor based on a 5V supply and the LED's different forward voltages.
I've been scouring Arduino and SE posts to find a solution but have come up with conflicting opinions as to the behaviour of the CC source, and also saw that current limiters on the output legs, like LM317s, might interfere with the high speed switching I need from PWM.
So I wanted to confirm if I am safe using series resistors in this configuration or if I should just use a 6-pin RGB LED and multiple CC sources instead. Thank you.
Edit: Added circuit diagram and my own measurements for the LED's forward voltage and current, as the datasheet is incorrect.
Sample resistor calc for red LED at 700mA: \$ \frac{5-2.36} {0.7} = 3.77\Omega\$


texts: Do AC voltages on datasheets refer to peak voltage or Vrms?

texts:
I'm attempting to find a relay to switch UK mains voltage (230Vrms); this gives a peak range of approximately 325V, -325V.

Consider something such as the datasheet for this relay. It has a rated voltage of 250VAC and a max switching voltage of 277VAC, are these referring to peak voltage or rms voltages, and perhaps more generally is it a safe assumption that all AC voltages specifed on datasheets are always Vrms?


texts: SoP to PoS conversion in the simplest way

texts: I have an exam in digital electronics in the middle of april and I've been trying for weeks to understand how F = B'C' + AC + A'C' in SoP can become (A+C')(A'+B'+C) in PoS. Could someone please take me through, step by step, either throught karnaugh map or normal SoP to PoS, how to do this particular problem?


texts: Control DC Motor on the Arduino directly from Analog

texts:
Is is possible to control a toy DC motor (5V) on an Arduino directly from the Analog (or Digital with PWM) pin without damaging the board? I know that DC motors are usually controlled via a transistor but I am thinking of controlling it this way. My Arduino code is:

    void setup() {
         pinMode(6, OUTPUT);
         Serial.begin(9600);
    }
    void loop() {
         int val = Serial.parseInt();
         if( val >= 0 && val <= 1024) {
             analogWrite(6,val);
             delay(5000);
         }
    }

My schematic:

GND---------------------MOTOR--------------|<|-------D6 (PWM)


texts:
My new PCB design is about 25 mm * 25 mm, this is not enough for a proper 868 MHz antenna ground plane, I am using the 0868AT43A0020 chip antenna where at least a 20 mm * 40 mm GND plane is required. The first prototypes confirm the weak RF performances. what is the standard practice when it comes to dipole antenna when the ground plane of the PCB is extremely small and not sufficient?

A picture of the PCB with the battery behind:


texts:
I've built a system which allows me to remotely control a well pump which is directly connected to 24v solar array. There is a regulated battery bank/inverter, but it's farther away, and the pump is built for PV direct anyway.
My issues seemingly happen in the morning when solar output is enough to boot my controllers (a Raspberry Pi, Sonoff, and an ESP32 LoRa board). Should a condition (like retained MQTT commands) enable the relay to trigger I notice that it causes a boot loop or the Sonoff to go into an "I'm my own AP now" safe mode.
I'm powering this off a 24v->12v DC buck converter, but I'm fairly sure I need to add a low current dropout component, but I'm not sure what my options are for this. I see a lot of solar charge controllers that have over-current protection, as well as low voltage disconnects, but very little about low-current supply protection. Perhaps I am thinking about this the wrong way?
For specs, my load is a 400w motor controller, triggered by 2 big 12v relays in parallel, which are triggered by 5v relays driven by the Pi or Sonoff (all in parallel for reliability). Keeping power off, especially to the Sonoff until a minimum current would probably help, as it ends up in a safe mode, triggering it's relay to toggle.


texts: Confusion with output wiring and signal conditioning

texts:
I’m little confused about wiring and signal conditioning the following instrument:

http://www.skypowerinternational.com/uploads/documents/4.3351.x0.140-161_WG-Geber-firstclass-advanced_analog_eng.pdf

Connecting diagram and technical data are on pages 6 and 7.

This instrument has two output options; analog and pulse. I need to use the pulse output (they call it rectangular digital signal).

In the connecting diagram there is both F - Source and F - Sink. And in technical data it shows pulse output with pull-up or pull-down resistors.

My questions are the following:

1) Do the D and S represent a MOSFET transistor?

2) Does this instrument have 2 different pulse outputs (F - Source and F - Sink)? What could it be the reason?

3) If I use for instance F – Source output should I use GND or AGND?

4) Why do I need extra pull up/down resistors?

5) Finally I couldn't find out what is the pulse output voltage with a Vs supply voltage (15-24V). If for instance the supply voltage is 24V and I want a pulse train with 8V 0V; can I then simply use a voltage divider or should I use an op-Amp?


texts: How can I determine the voltage insulation rating of magnet wire?

texts:
As an extension of my previous inquiry into air-core chokes, I'm trying to determine the voltage insulation rating of magnet wire, without much luck. Few of the audio air-core choke manufacturers list that data, and none of the magnet wire manufacturers I've checked give it either. For example, this company lists the type of insulation used, and its thermal properties, but nothing about its voltage withstand ratings. This appears to be common practice. I see references to insulation grades (1, 2, or 3), which seem to be how many insulation layers are present on the wire, but I still haven't found any voltage rating for those grades.

How can I be sure that the insulation on magnet wire will not break down under a given voltage? Am I not looking in the right place for this rating? Am I looking at the wrong kind of magnet wire for high-voltage applications? Are we required to build chokes such that consecutive windings of magnet wire are close enough in voltage that the insulation rating of the wire doesn't matter?


texts: Power of a microcontroller, but with more memory - what fulfils this need?

texts:
I'm a hobbyist with little experience. Usually I play with Arduino Pro Mini or ESP8266. I can make them do simple things I want, but for obvious reasons I can't give them too many features at once.

E.g. if I try adding a OLED with configuration interface, or logging to SD card, or persistent variable storage and button debounce logic, to an existing program, it becomes too much for the device to handle.

Essentially, I'd like something no stronger than what I'm using, but with an order of magnitude (x20 or so) more FLASH and RAM, or something to the same effect.

What I've considered:

external memory: can't put code on it (?)
(on ESP8266) replacing the flash memory with a larger one: not enough
optimizations: not enough
multiple microcontrollers: doesn't scale well, takes up space, uses more power
upgrade to Raspberry Pi Zero, C.H.I.P., etc: overpowered, but best option so far
run all the logic on an external server: limited usefulness

So the question - is there a good (inexpensive, not needing many changes to existing software) product (device class) or technique that fulfils this need?

[EDIT]
Further considered ideas:

external SDRAM, loading code from SD card: time investment, and it's essentially a Pi Zero with a much weaker CPU

It seems the answer might be that if I'm looking for a relatively mainstream (easy and cheap) solution, I should accept the greater power usage and use an ARM computer. Can anyone confirm?

[EDIT2]
Thank you all, I now have an uotline of available product tiers.
The general thoughts I get are:

SRAM prices will put anything up to and including ARM Cortex M4 at a similar level, should choose by support quality and power usage
where power conservation isn't a concern, a small SBC will offer cheap resources


texts:
What is wrong with following Verilog code where I am trying to pass a one-dimensional array?

module stimulus;
wire [3:0] max,med,min;
reg[3:0] row_data[0:2];
reg cin;
sorting_three sr(max,med,min,row_data,cin);      // line no.27
initial begin
row_data[0]=4'b0010;
row_data[1]=4'b1001;
row_data[2]=4'b1010;
cin=1'b0;
end
endmodule

It's giving an error like:

  ERROR:HDLCompiler:251 - "stimulus.v" Line 27. Cannot access memory row_data directly
  ERROR:HDLCompiler:598 - "stimulus.v" Line 21. Module stimulus ignored due to previous errors


texts: PCB Stack up 4 layer Micro vias, Stacked Vias and Buried Vias

texts:
I am designing a 4 layer board in which I HAVE to use blind and buried vias. This is a very dense board with (SOLID COPPER ON LAYER 4, No exceptions )

I am planning to use
1.) 1-2 microvia and 2-3 Buried vias.
2.) 1-2 and 2-3 Stacked microvias. ,

So Can you suggest whether I could go with the first configuration or I should switch to the 2nd configuration keeping cost in mind.Which configuration is cheaper.

Keep in mind that this is not HDI PCB just a mixed signal board of analog and digital

I should mention that PCB Is 0.4mm thickness. So more then 4 layers is not possible


texts: I am building a digital alarm clock, and I need a chip holder for the LM8560 chip. I tried a sop 30 to dip 30 holder. The chip fits on width but not length. The chip is to long and even if I used sop 40 to dip 40 chip holder not all of the pins on the chip would align with the holes in the socket. I have tried making a chip holder by drilling holes in a piece of MDF, sitting the chip in those holes and soldering wire to the chip pins. However in the process I believe I damaged the chip and the circuit will not work properly. Could someone please recommend me a chip holder that would work, or a method of building one that would not require soldering anything to the chip pins? Or even a company who makes custom chip holders?


texts: Magnet that needs power to turn off? Inverse coil?

texts:
I have never heard of such thing. But it would really suit my needs.

I'm inventing a device and during it's operation, it should be able to catch an iron object any time (with a permanent magnet). The device should be mobile, so using inductor would really reduce the time of operation.

But the device must also be able to turn the field off, so that the objects can drop down.

I only could think of one concept: Put inductor behind a permanent magnet in a way that when the inductor is turned on, it's field will negate the permanent field of the magnet.

As you see it's my attempt to draw a coil connected to permanent magnet (isolator is in-between). When the coil goes on, it should produce field of oposite direction to the field created by magnet.

Is this possible? Is there a better trick?


texts:
I have zero experience with electrical engineering and am hoping that someone can a) tell me if this is possible, and b) direct me to some material where I can learn enough about this to ask intelligent questions. I can't find anything on a hobbyist level and am not looking for college level courses.
I have a small water pump https://www.amazon.com/gp/product/B07SJGKFT7/ref=ppx_yo_dt_b_asin_title_o07_s01?ie=UTF8&psc=1
It is a 3W submursible pump that plugs into the wall. I want to add an LED so that when it is plugged in and running, an LED lights up as well. The LED needs to be waterproof. I plan to use this to make an illuminated tabletop fountain.
Is this a thing that is possible, and if so where can I begin to learn about this? All I can find are college level engineering courses, and I don't even know if this is a thing that can be done.
Sorry if I sound really stupid, this is outside my area of expertise and Google has been no help.


texts:
I am designing a project where I'm going to use the MAX1709 step-up converter.
There is a possibility to switch the converter ON/OFF with the help of ONA/ONB inputs, but according to schematic in the datasheet the input voltage will be available on the output even if the IC switched OFF because the input DC-connected to the output via a schotky diode.

Could you confirm, please, if I understand this schematic correctly ?
If so, is there a way to "completely" switch the circuit so that there is no voltage on the output ?


texts:
I have a BLDC motor that due to some limitations (mechanical) half of its coils most be removed like the following:

Now my question is, is this motor just worked? how about performance?


texts: How to look for a good quality 11mm rotary encoder?

texts:
The rotary encoder attached to the wheel of my dear logitech MX1000 started glitching a few weeks ago. I took it out, tried cleaning it the best I could but it was still bad.

So I went shopping online for 11mm mouse wheel encoders and got 4 random ones, each costing around 30 - 90 cents. I tried them all and they all suck even worse than the glitchy original encoder.

I need to find a better one. Usually that would mean something more expensive like the 2-5 dollar encoders I saw titled specifically to some other high end mice but unfortunately none of those would fit. All of the 11mm encoders are less than $1 and from the little batch I got, seem to have no real difference in how well they perform despite the price.

Does anyone know a good company that makes those? Or perhaps some kind of a specification detail I should look out for?

PS! Yes I know I could just buy a new and probably better mouse but I really like this one. I've replaced pretty much every button and the battery several times over its 10 years of service and I'm not about to give up on it now.


texts: Positive Photo Resist for lift-off & Negative for EBL?

texts:
I would like to know two things about Photo Resists (PR):

How is positive photo resist used for lift-off?
What is EBL and why negative photo resist is used in this case?


texts:
I am trying to make a diagram for caravan electric system.As a part of it I have to recharge my batteries from shore/main current. I am thinking of using 230Ah AGM batteries. I will use a 30A 12V charger to charge my batteries from shore current. But I am not understanding which cable should I use to connect the batteries with the charger?
I have been searching a bit and found that most people use 16mm cable which are 110amp - to charge their 110amp batteries. so from there I get the idea that I need same amp of cable as my batteries.
But then again when I search for 230amp battery cables then search results come up with cables rating with awg.
So, how do I decide on the cable? there are awg, amp, mm for cables.


texts:
I am trying to encapsulate my fast adder design with a top module containing input and output registers. All combinational logic is present in the instantiated module. The purpose of top design is to provide operand values to the adder and to store the calculated output at each posedge clock.  When I try to do it as shown below, the output is delayed by one clock cycle. Is there any way to modify the code so that the output registers are updated with the results in the same clock cycle as input registers? I am new to Verilog and I don't totally understand different types of assignments. Also, I will be synthesizing this design later.

module four_bit_hca_reg(
    clk,
    S_out, C_out,
    A_in, B_in, C_in);

input [3:0] A_in, B_in;
input C_in, clk;
output [3:0] S_out;
output C_out;

reg [3:0] A, B, S;
reg Cin, Cout;

wire [3:0] Sum_wire;
wire Carry_out_wire;

four_bit_hca adder (.A(A), .B(B), .Cin(Cin), .S(Sum_wire), .Cout(Carry_out_wire));
assign S_out = S;
assign C_out = Cout;

always @ (posedge clk)
begin

A <= A_in;
B <= B_in;
Cin <= C_in;
S <= Sum_wire;
Cout <= Carry_out_wire;

end

endmodule


texts: Do I have to use external clock for ATmega ISP programming after changing fuse bits?

texts:
After programming an ATmega microcontroller via ISP (SPI) interface and changing the clock-related fuse bits, I'd like to reprogram it again. Will I have to connect it to an external clock now to do so, or will I always be able to program it by clocking just via SPI's SCLK line, without external clock (like in image below)?

(in the image below, the programmer is a Raspberry Pi)


texts: Biased single-source relaxation oscillator not starting

texts:
Vcc is 5 V , first op-amp LM358 provides 2.5 V ground for easiest possible relaxation oscillator build with MCP661 (2.5/5.5 V supply, 60 MHz operational range). I wanted to use it to measure values of capacitors. Yet for some reason it doesn't start but hangs with the output at 2.5 V when connecting any capacitance.

Please point me towards what I might have done wrong.


texts:
I am seeing a problem with Micrel Ethernet PHY KSZ8721BLI.

Because of some mechanical constraints, the PHY is located near the edge of the main board and a small card edge connector. The board slides into a housing, and at the end of its travel, a smaller board mounted the back of the case and sporting a card edge connects to the card edge connector of the larger board mentioned above. This small board is home to the Ethernet RJ45 connector and magnetics, and no particularly long traces are present.

My problem: I am seeing failures of the TX+/- and RX+/- pins on the Ethernet PHY, all shorts. I have not observed a cable discharge event (CDE) when plugging in an Ethernet cable once the board is in place, and my cable is only 3 m. I've looked at the behavior of the connector during insertions and extractions of the larger board and haven't seen anything strange. Also, this is a design that I've built repeatedly and never had a problem with before.

The circuit is basically a Bob Smith connection with 0 Ω resistor instead of the typical 75 Ω resistor.

Assuming that this isn't just a bad lot of Ethernet PHY ICs, does anyone have any ideas of what might kill the PHY TX and RX pins?


texts: What will be Resistance for maximum Power transfer from network A to network B?

texts:
simulate this circuit – Schematic created using CircuitLab

Can we apply Maximum Power transfer theorem if we are given two networks both with voltage sources.
In solution it was said that for maximum power transfer the voltage across the network B should be half of Vin and current through R1 should be same as if a resistor resistor of 5 ohms is connected across boundary port of Network A and Network B.I don't know if I can trust it.I cannot prove it .


texts:
I would like a microcontroller already interfaced to a WiFi module, with the WiFi interface taken care of.  Also, I want to be able to program the MCU to interface sensors or whatever...possibly with the outputs broken out for ease of connecting. Almost like a development board, but small and cheap enough to interface a few sensors or such and send over wifi.

These guys are close Roving Networks, but the interface to the MCU is very limited.  I know wifi is overkill for sensor data, but it is also ubiquitous.

I guess what I am saying is that I hate laying out boards.  I have done some serious google searching and haven't found anything.  Anybody using anything like this?

Update:
The ESP8266 is probably the answer to this question


texts: Is it possible to make dram using bjt's or is it only possible with mosfet's? If not why not? Is there an advantage in using mosfets instead of something like a bjt ?


texts: Effect of secondary coil in a resonant transformer on resonant frequency

texts: I have a friend who has asked me to help them with tuning their tesla coil. Every schematic I can find for building one simplifies down to essentially the circuit below. I recognize the primary circuit as an LC circuit. And I see that essentially what we have is a resonant transformer. My question is, how do the primary LC circuit, and the secondary coil interact to create the resonant frequency. I can solve the primary LC circuit easily enough, but what role does the secondary play on the frequency emitted?


texts: Beginner question so please go easy on me. My question is around what is the correct way to have a common ground reference on a circuit at that 2 different voltage sources. the below schematic is a simplified version of the problem. The device I am developing  (represented in this schematic by a simple LED) is all driven by a 12v wall adapter but the way it knows to activate is when a 24V AC power source activates. I was trying to us a simple MOSFET with a half wave rectifier to detect when the 24VAC source turned on but the question is how do I tie the ground together so they have a common ground reference? Is it proper to tie the ground together like in the diagram? If not what would be a better solution?


texts: What does 'ground' look like on a breadboard?

texts:
Given the following circuit:

What would this look like on a breadboard? For example, what is 'ground' on the right? Is there a particular 'component' that can be used in a breadboard to act as ground (I'm usually using a 9V battery as the voltage source).


texts: How can I correct instability in a push-pull transistor amplifier?

texts:
In our EE lab, we had to build the following amplifier.
  It is from this lab manual, page 40.  A week ago, I built it successfully, with 2n3904/3906 and d44vh10/ d45vh10 for the power amplifiers (Q3,Q4).  It was driving an 8ohm speaker and all worked fine. I put my circuit in a box and came back this week to demonstrate its operation to the lab instructor but suddenly my circuit just oscillated at a very high frequency and nothing I did could correct it.  I have rebuilt it twice now and somehow it is stable until I apply a signal and increase the volume - then it just goes crazy.  At one point it worked perfectly fine when \$R_L\$ was a 10K resistor.  Once I connected the speaker, it just went crazy and the transistors started heating up.  What could be causing this instability and how can I correct it?
I have noticed the issue is at the output stage - when I remove the op amps and connect the midpoint between the diode pairs to ground, it still goes crazy so I think the problem is within the transistor part.

Component Values:

R1=R2=5k
R3=R4=1ohm
Vsupply = +/- 15V
Op Amps: ua741 8-dip


texts: Tips for solving difficult block diagrams?

texts:
I've gotten the hang of solving block diagrams, i.e. condensing them to a transfer function. I'm aware that one may be solved in multiple ways.

For simple diagrams, it's fairly straightforward to see where the first "transformation" should be applied, and with which rule.

It's more difficult to apply this to something more challenging... to just go in order of the rules, i.e. first search for negative feedback blocks I can combine, then blocks I can combine in series, and so on. Or, for example, if both are present in the diagram, I can condense either area first or apply both rules in one step.

It appears daunting to "wing it" and e.g. move a branch before a block to see where it takes you, similar to Sudoku (i.e. we're only given guidelines, but because there are multiple ways to reach the solution, we should "wing it" and fill in an 8, even if it risks us going back from the beginning to try again).

From many tutorials I've seen, people mention the various rules, but no one ever seems to mention a step-by-step strategy to solving more difficult ones.

What about for trickier block diagrams, where the solution isn't that obvious? Where does one start?


texts: Can't identify the mistake in my circuit

texts:
After finally deciding to transfer my projects from a breadboard to a stripboard, I managed to put this circuit together, but the soldering was the ugliest thing I have ever seen, so I threw it out and started on a different board. The thing is, this one doesn't work. No matter the amount of tracing I've done, I can't figure it out. It works fine on a breadboard, though.
P.S. excuse the ugly soldering and the damaged track.


texts: What is this triple-transistor arrangement called?

texts:
For an old Fuji 2DI200D-100 power transistor module, it uses three transistors internally for each half-bridge:

The circuit in question doesn't connect to the middle bases at all, just B1 and B2, so this (dual) triplet is being used solely as two big transistors. Is this called a "triple Darlington pair?" "Darlington triple?" Or is there some other name for this arrangement?


texts:
I am trying to make a current-controlled resistor in  OrCAD pspice, so that R = I^2, where I is the current going through the resistor. I have tried to implement it using a voltage-dependent current source, but I always run in to a problem with floating nodes. Here is the netlist and error message.

**** INCLUDING SCHEMATIC1.net ****
* source TESTS
R_R1         0 N08058  1k TC=0,0
V_V1         N08058 0 10Vdc
G_G1         N07933 0 VALUE { V(N07933,0)/I(V_V4)**2 }
G_G2         N09209 N09253 VALUE { V(N09209,N09253)/I(V_V3)**2 }
V_V3         N08058 N09209 0Vdc
V_V4         N09253 N07933 0Vdc

**** RESUMING test.cir ****
.END

ERROR(ORPSIM-15142): Node N07933 is floating

ERROR(ORPSIM-15142): Node N09253 is floating

I have tried to figure out where I going wrong, but the I don't know how to fix it without altering the behaviour of the circuit. Can anyone tell me what I am doing wrong?

To try to make the resistor I made the circuit below for testing. It works when I only have one resistor, but when I put them in series, I get in trouble.


texts: 2-stage BJT amplifier for low impedance load

texts:
I need to design a 2 stage bjt amplifier that would amplify a 0.1uV waveform at least 100 times on a 4ohm load. How do I choose the proper stages for amplification? I was thinking about the most common CE-CC amplifier but I'm not sure if that's the best choice

UPD: I made the 1st stage (CE) to have a gain of a little more than 100 but measured at 22kOhm load, Is that good enough to use with the CC amplifier?