texts: What's the typical way to manage components for a team in Altium? Component libraries in a vault? SVN Database? Other?

texts:
I'm an EE for a growing company, and I'm looking for what's typical to manage components across multiple designs. When I say growing, I mean that there used to be one EE, as of last year I got added on, and we're looking to seriously expand the team.

Previously/ currently, we had an integrated library that was managed like any other file in SVN. Searching through similar questions, integrated libraries is essentially where the discussion stops. Even with two people it's not a real solution to just use an intlib, but it worked for a relatively small number of designs. We've had issues where a component needs to change across multiple designs, and using a single integrated library for multiple people is a really crappy way to manage these issues. For instance, I want to be able to update a component, and every person and every design using that component can pull the new parameters automatically.

When looking for a better way, it looks like Altium either points you to an SVN-based component library (https://techdocs.altium.com/display/ADOH/Working+with+Version-Controlled+Database+Libraries) or a vault-based library (https://techdocs.altium.com/display/DMAN/Component+Management). Naturally, the documentation online would leave you to believe using a Vault is the holy grail of component management - but I have concerns if people are working without VPN access, etc. Which route does your company use and is it ideal?


texts: Can this Eaton T0-2-8211/E changeover switch between multiple sources

texts:
I have this Eaton 1|0|2 style changeover switch T0-2-8211/E. Can I use this to switch between 2 different input sources?
My intention is to use it to switch between shore and generator power on boat. It's not going to be used frequently so no automation is required. I just want to be able to switch the input source to my AC distribution panel whenever I leave the dock.
The wiring diagram that came with it looks like this
So I thought I could just wire Input 1 (shore power) to 1 & 3, Input 2 (generator) to 5 & 7, then have the output to the AC distribution panel be 2 & 6.
But when I tried this I had severe voltage drop whenever I applied any load. So it works fine when measured with a AC voltage meter without any current being drawn, but as soon as some load is applied the voltage drops to ~0 and get's very unstable.
What am I doing wrong, is it my wiring, or is this switch not suited for this application? I see it sometimes mentioned as a "manual motor controller" which is not what I'm using it for, but I figured it was just a switch.


texts: Does an SAR ADC discharge the sample capacitor?

texts:
Most microcontrollers use successive approximation for their ADCs. These charge up a sample and hold capacitor, and then use this capacitor as the basis for the successive approximation algorithm.

I'm working on an extremely low power project, where the charge held by the capacitor starts to become significant. The question is, after the adc charges up the capacitor, does it discharge it? I assume there will be some leakage as well, but I'm curious as to whether there is an intentional discharge step. If it's sampling the same voltage repeatedly, will there be a significant (microamps) current flow?


texts: Short circuit protection stage in the 741 op. amp

texts:
The 741 op amp has a rugged design with a short circuit protection feature if any one could shed the light on this mechanism where I have found it to be on of the most power efficient protection circuits that would not drain the power of a battery.
I would really appreciate it and thank you in advance for you efforts!


texts: Building a battery powered +-15V DC Power supply PSU

texts:
I am building a +/-15V Power supply to power a sensor, the sensor draws 25mA. Unfortunately, I'm having some difficulty with it. The design is as follows:

6V AAA battery pack plugged into a DC/DC Boost Converter
Boost Converter set to output 30V from the regulated output
Output is split into +/-15V using Linear regulators (LM7815/LM7915 pairs)
+/-15V and Ground is plugged into sensor

The boost converter I am using is rated for output voltages up to 37V:
https://www.jaycar.com.au/arduino-compatible-dc-dc-boost-module-with-display/p/XC4609

The 'data sheet' (if you can even call it that) can be viewed at: https://www.jaycar.com.au/medias/sys_master/images/9004196134942/XC4609-dataSheetMain.pdf

The circuit to split the 30V into +/- 15V has been adapted slightly from https://www.head-fi.org/threads/virtual-ground-regulated-and-rail-splitter-circuits.654485/

I have not included an LD1085 because the output of the boost converter is regulated.

The schematic is:

simulate this circuit – Schematic created using CircuitLab

I have used an LM317 regulator instead of the LD1085 Low drop out regulator. This was mainly due to price and what I had available. I have also used smaller capacitor values than what was quoted.

Simulating the circuit shows the correct values. However after building the circuit its not working properly.

But when I plug in the rest of the circuit the DC boost converter the screen turns off, I think its due to a short. The LM7815 gets proceeds to heat up, I think that it's trying to regulate from 15V to 30V.

The circuit itself is built on perfboard, and I ensured all connections were correct using a program called Fritzing. http://fritzing.org/download/

The circuit can be seen below


texts: what is the purpose of having a "thru cal" on RF PCB?

texts:
I often find a thru cal on RF PCB like picture below.
What is the purpose of having this thru cal thing on the board?
One purpose I can think of is to test whether the designed transmission line is truly 50 ohms over the frequency of interest.
I did some research online and there are some people saying that the purpose of this thru cal is for "through-reflect-line" (TRL) testing. But I was not convinced with this argument since TRL technically needs other two lines (reflect and line).
Can anyone explain this to me from their experience?


texts: Only charge capacitor when button pushed then turn on LED momentarily with capacitor when button released

texts: I am trying to make circuit to turn on an LED momentarily. I would like to charge the capacitor when the button is pushed, then when released turn on the LED momentarily with the capacitor.


texts:
In a function generator, when I set Zout to be 50 Ohm, and Vpp is 1V. Is this  Vsource, or the Vload when I have a matching load of 50 Ohm?

simulate this circuit – Schematic created using CircuitLab


texts: Reasons to use open circuit stub over a short circuit stub

texts:
I am having trouble with this question which states: suggest two reasons why the use of an open circuit stub might be preferable to a short circuit stub in microwave circuit design (microstrip)

Could someone please help


texts:
I'm working on an old portable cassette recorder I had lying around and was wondering if it's possible to slow down the motor with an LM317 and a potentiometer. I've read about PWM, but I'm not sure how to do that or if it'll fit inside the case.

edit: it's a Sony TCM-818, the motor is hooked up directly to the motherboard, there's no circuit board/motor controller on the motor itself


texts: Understanding image display on a TFT/LCD display

texts:
I am doing some reading about interfacing displays with an MCU. I came across this block diagram:

About the display controller, the following is mentioned:

The display controller is continuously “refreshing” the display,
transferring the framebuffer content to the display glass 60 times per
second (60 Hz). The display controller can be embedded either in the
display module or in the MCU.

Today, we have a lot of use cases where display is static for most of the time. Foe example - our laptop and mobile screens.
Does the controller refresh the screen while displaying a static image? Or does it dynamically starts refreshing when there is a change? (E-ink displays are static when no change is required, for example.)
If the controller refreshes the display even during a static screen, is it not a rather inefficient way to do it? Are they doing it to give a better experience to the user (making the display more snappy)?


texts: thyristor latching and holding current confusion

texts: i am a bit confused between the terms latching and holding current of thysristor. I know that latching current is the minimum current required to maintain the thyristor in on state after it is turned on and gate pulses have been removed while the holding current is the minimum current to maintain the thyristor in the on state. i need to know what is the state of thyristor in between the latching and the holding current.


texts: What are these connectors at the edge of the chassis called? I thought they were pogo pins, but it seems like they're not uniform and are keyed? How well do these kinds of connectors stand up to repeated mating?


texts: Possibilities for allocating memory for modular firmware design in C

texts:
modular approaches are pretty handy in general (portable and clean), so I try to program modules as independent of any other modules as possible. Most of my approaches are based on a struct that describes the module itself. An initialization function sets the primary parameters, afterwards a handler (pointer to desriptive struct) is passed to whatever function inside the module is called.

Right now, I am wondering what the best approach of allocation memory for the struct describing a module may be. If possible, I'd like the following:

Opaque struct, so the struct may only be altered by the use of provided interface functions
Multiple instances
memory allocated by linker

I see the following possibilities, that all conflict with one of my goals:

global declaration

multiple instances, allcoted by linker, but struct is not opaque

(#includes)
module_struct module;

void main(){
   module_init(&module);
}

malloc

opaque struct, multiple instances, but allcotion on heap

in module.h:

typedef module_struct Module;

in module.c init function, malloc and return pointer to allocated memory

module_mem = malloc(sizeof(module_struct ));
/* initialize values here */
return module_mem;

in main.c

(#includes)
Module *module;

void main(){
    module = module_init();
}

declaration in module

opaque struct, allocated by linker, only a predefined number of instances

keep the whole struct and memory internal to the module and never expose a handler or struct.

(#includes)

void main(){
    module_init(_no_param_or_index_if_multiple_instances_possible_);
}

Is there an option to combine these somehow for opaque struct, linker instead of heap allocation and multiple/any number of instances?

solution

as proposed in some answers below, I think the best way is to:

reserve space for MODULE_MAX_INSTANCE_COUNT modules in the modules source file
do not define MODULE_MAX_INSTANCE_COUNT  in the module itsself
add an #ifndef MODULE_MAX_INSTANCE_COUNT #error to the modules header file to make sure the modules user is aware of this limitation and defines the maximum number of instances wanted for the application
on initialization of an instance return either the memory address (*void) of the desricptive struct or the modules index (whatever you like more)


texts:
I am creating my first 12V to 5V buck converter with the TI TPS56339. I've heard that the PCB layout is critical and before I send the PCB to production I wanted to get it reviewd. I tried my best to follow the guidelines for the component layout.
Could you please review my layout?

Thanks

Thanks for your answers. Based on your feedback I created another design. Unfortunately it is not possible to change the thermals on individual pads in Eagle. Is the design better now?

Here is my 3rd design. I switched to the LMR23630 due to better part availability. I tried to follow the design guidelines in the data sheet. The output capacitor is a little far away from the IC's PGND pin. Will that be a problem?


texts: How to interpret the values sent by an MPU-9255?

texts:
Well, I am using this holiday in Brazil to improve my skills in C. I have learned how to use I2C and how to communicate with the MPU9255 (with help from this question). The last trouble I am facing is that the sensor is returning wrong values. The value returned is floating from 0 to 65000, but it is not linear.

I think that is because I am making some confusion on the data types or bytes merge on my code. Can someone help me revising my code?

    uint8_t Test[] = "\n AccelX: \n";
    HAL_UART_Transmit(&huart1,Test,sizeof(Test),100);

    //SET X_HIGH REGISTER ADDRESS
    i2cData = 0x3B;
    HAL_I2C_Master_Transmit(&hi2c1, adressMPU, &i2cData, 1, 100);

    //REQUEST 6 BYTES OF DATA (ACCEL X, Y AND Z)
    HAL_I2C_Master_Receive(&hi2c1, adressMPU, receive_buffer, 6, 100);

    AccelX = (char)receive_buffer[0]<<8 | (char)receive_buffer[1];
    AccelY = (char)receive_buffer[2]<<8 | (char)receive_buffer[3];
    AccelZ = (char)receive_buffer[4]<<8 | (char)receive_buffer[5];

    //PRINTA NA SERIAL 1
    len = sprintf(buffer, " %i\r\n", AccelX); //sprintf will return the length of 'buffer'
    HAL_UART_Transmit(&huart1, (uint8_t *)buffer, len, 1000);

    HAL_Delay(500);

Update:

I just noted one thing: from 0 to 16768, the sensor measurements are right, but when I upside the axis, the sensor goes from 65536 to ~49000 when should be from 0 to -16768. Surely is a conversion error, but I still not can see where exactly is the error.


texts: Is it better to route a pad to a trace, or a trace through a pad?

texts: When routing a PCB, is it better to route a trace through a pad as in 1 below, or to route a pad to a trace as shown in 2 below?


texts: Are values of resistivity independent of the cross-section and length of the resistor?

texts: I was reading resistivity values for different materials on the wikipedia page. They report the values for standard temperature, but they give no information about the cross-section or length of the material/resistor. Are this values independent of the cross-section or the length of the resistor?


texts: How to find a compatible upgrade for a phone camera

texts:
I have a set of Android video glasses which are based on the PRIXTON C18 phone. I'd like to upgrade the camera to a better one - specifically one that supports changing the shutter speed as the current one does not.

I've tried a couple of different cameras from Ebay that look similar to the socket (right shape/number of pins) however they have all been too big or small to click in. Here's what the socket and old camera look like:

Socket on the android device

Camera

My specific questions are:

Is the socket type shown above a standard socket and if so what do I need to search for to find cameras which will be compatible?
If the socket type is standard, is it a plug-and-play type thing - i.e. will all camera devices that fit the socket likely just work?


texts: Is there a difference between these two circuits?

texts:
I might not have drawn the second one right, but imagine if it was a live wire in a bathtub going through the water and the plumbing to ground instead of returning to neutral, except way more volts.
Is there a difference between the voltages between the two sets of prongs, if the source voltage is the same and high?


texts:
For a class I have to filter out two signals separately and demodulate them (AM) before processing them any further. The only topology we have seen so far for active filters is the versatile Sallen-Key.
However this one is way too instable with real components for a filter with a high Q factor. So I am  looking into other topologies(come accross variable state so far) and I realized how hard it is to get good references on this topic and our course is not very well sctructured so I don't feel like it's going to come from them

Any good references on the internet or textbooks I could ''acquire''


texts: How to divide signal level from function generator

texts:
I looked for this answer but was unsuccessful so I want to ask the experts here.  I have configured an op amp in non-inverting mode (the first in a chain of 3 stages).  It is for amplifying extremely low level noisy signals so I'm using lower resistor values.  The input resistor is a 100ohm and the feedback resistor is 3K ohms.  I'm feeding the circuit on the bench with a sine wave from my signal generator which has an output impedance of 50ohms and a minimum level of 4mV.  I need to go lower to about 5uV minimum.  The generator increases in 1mV increments.

My question is how should I configure a voltage divider in order to divide this signal down to 5uV (minimum) and maintaining a 50ohm impedance match.  I need to measure the output of the entire amplifier chain while knowing what level is going in versus what level is coming out.  Hope this makes sense and hope I've included all needed info.  Thanks for the help.
FJ


texts: Does gcode require a response code from the interpreter?

texts:
I am making a little machine that interprets g-code and moves some steppers around appropriately. I am using an arduino as the brains on the machine side and sending commands to it from some software I am also building.

If it receives a command to move the steppers, lets say, a thousand steps how does the computer know when its done moving and ready to receive another command?

Once the arduino receives a command, "L101G01X9Y10" for example, should it respond with any sort of code to say "Ok I got it, give me another command"?

NOTE:
I am not looking for a custom solution in this case. I am trying to establish what the standard protocol is


texts: Is designing and producing a dirt cheap charger really that hard?

texts:
Recently one blog service (all text is in Russian) published a curious post. The author proposes to add mobile phone charging capability to each 4-pieces pack of AA alkaline batteries.

The idea is that very thin aluminum foil wires are "drawn" right on the inner side of the cardboard pack to interconnect the batteries and a "dirt chip" very short micro-USB cable is connected and hidden inside the pack.

One of the comments says it won't fly for a number of reasons, including

need for spring-loaded contacts, which also implies stronger pack
need for pack sealing to prevent contacts corrosion
need for a certified USB cable which is not dirt cheap
extra circuits to prevent shorting, overcurrent and overcharging protection

What I want to ask is - is it really that hard? Is it really near impossible to produce a disposable dirt cheap charger?


texts: How to deal with the ground node in circuit graph and the gains of dependent sources?

texts: in this circuit I am asked to find the gains of both dependent current and voltage sources. I've drawn the circuit graph and done the analysis that I had supposed. But I am not sure about whether there should be four or five nodes in the graph. I supposed that there are just four nodes since the currents before and after the ground (from right to left) are the some so the difference in voltage also should be the same. But after that I had i3 in a negative value! If this is correct should the gain g be positive or negative?


texts: How to configure NPN transistor as switch and adjust current flow?

texts:
Consider the following circuit:

As signal a 100 kHz square wave (between 0 and 5 volts) generated by an Arduino.
I want to control the transistor so it will let the current from the supply pass through when the square wave is ON (5 volts) and in to the circuit (represented by a resistor/impedance in the image below). The supply will be at 5 volts.
And the transistor NPN used is a NTE85 with DC gain between 100 och 300 among other characteristics.

I think a base resistor might want to be added to control the current/voltage at the base and therefore set the transistor in cut-off mode and saturation mode to act as a swtich. But I'm not quite sure how to go about all this.

What do I have to think about to make the above work? What do I need to add/change/calculate? What characteristics of the transistor do I need to consider etc.?

I little guide for this particular case would be much appreciated.

Thank you!


texts: Active Power Factor Correction Operation Mode

texts:
I'm trying to design a SMPS power supply with potentially widely varying loads, from say a watt or two to ~150W, and I want to include Active PFC because of the medium power load, as well as to use this as a learning experience for getting familiar with active PFC design.

Looking through the literature, I found the general pros/cons list for different active PFC operation modes:

Discontinuous - Limited in max power output of ~300W, which isn't a significant factor here. The peak current through the inductor is larger, though, so better EMI filtering and more expensive inductors must be used. There's no significant reverse recovery current so the boost diode can be "smaller". In general the actual controller chip is simpler/cheaper.

Continuous - Can achieve high power outputs. The peak currents through the inductor are smaller, so smaller EMI filters and inductors can be used. However, the boost diode needs to have relatively fast reverse recovery times. In general the actual controller chip is more complicated and expensive. As far as I can tell, though, this last point of cost/complexity doesn't seem large (for low-quantities at least).

There are also various sub-modes like critical conduction mode (discontinuous), continuous conduction mode (continuous), average current (continuous)...

I haven't found any reasons why continuous (in particular, average current) modes can't be used effectively at lower powers, or would not be as good (performance wise) compared with a discontinuous mode. Are there any reasons/data why?

Which operation mode should I pursue and why?


texts: Coordinator + Repeater Xbee + End device configuration

texts:
I am trying to work on a Xbee based solution for transferring data from with in a specified area.I am using Xbee865LP for the same project.

Now what i want to implement is Make one device act as

Coordinator - Combination of Xbee + RPI
End_device - A microcontroller + Xbee + Some sensor
Repeater - A Stand alone Xbee.

and make Controller talk to end device via repeater. Now as i was understanding earlier that we can just set DH and DL of coordinator and end device to their SH and SL, put up a repeater in-between and it will work out. But it didn't happen as i thing flow of data might might be taking place like this(if it would have happened)

Coordinator send data to repeater(with coordinator DL and DH being fixed to that of repeater) and repeater will send data to end device(with repeater DL and DH being set to that of end device). So it is quite easy to work if flow of information/data need to take place like this Coordinator-->Repeater-->End device.

Now my first question is what if data/information need to flow in opposite manner i.e. End-device-->Repeater-->Coordinator. So a simple answer is we can use API mode, first set the repeater DL and DH to SL and SH of end_device , send data and then set the DL and DH of repeater to SL and SH of coordinator. But i dont want to work in API mode.

My next question is , isn't there any way, with which we can simply increase the range of transmission between Coordinator and End-device? Probably making repeater work in a mode,in which it simply relay the data which it received ? I know its a stupid question, when i know that it cannot even receive the data when the data have DL and Dl of end device and not that of repeater. Can any one suggest me any alternatives?


texts: Beginner problem: Debugging power supply

texts: I am debugging my power supply using an oscilloscope. I have uploaded pictures of my setup, including oscilloscope reading, wiring (just power and ground with jumpers), and the power supply specs. The power supply is supposed to output 5V 10A DC, but the oscilloscope at 1X is reading ~480mV. Is this power supply bad, is there something wrong with my setup, am I reading the oscilloscope incorrectly, or is it something else?


texts: Nodal analysis; am I doing it correctly?

texts:
Here is the circuit:

In the following, switch S has been open for long. No initial energy.

C = 10 uF.
R0 = 24 Ω
R1 = 12 Ω
R2 =
18 Ω
R3 = 6 Ω
Power Pr3 dissipated in R3 is 24 watts.

What are the powers dissipated Pr2 and Pr1 in R2 and R1 resistances?
What are the nodal voltages V3 and V2?

Here is my attempt:

I started by using R3 power dissipation of 24 watts and solving for current by sqrt(24/6)= 2 A

Then, multiply 2 A * 6 ohms= 12 V so V3 = 12.

Nodal analysis: all loops going clockwise

Loop 1: V1- V1/24 - (12-V2)/12 =0
Loop 2: V2- (V2-12)/18- 12/6 +V2/12


texts: Reading a 32bit IC counter on from a computer

texts:
I am working on a design to count the mechanical cycles of a piece of equipment. It has to be a 32 bit counter and be robust. I have a working prototype using a sn74lv8154 IC, configured as 32bit.

There are 2 main issues with the design
1. Reading the count
2. Losing the count

Reading the count
For testing and prototyping purposes I have used an Arduino to access the 4 byte registers, and display the count value on a lcd screen. However, the Arduino is proving to not be robust enough. Ideally I would like to read the count data using a laptop, but I have no experience directly interfacing a PC with an IC. Someone has suggested HyperTerminal, but again, I have no experience at all with this.
The prototype uses a battery to power the device. If the battery runs flat or is disconnected the count value is lost. This is a major problem, a solution using a non-volatile counting IC would be preferable but I have not been able to find one from searching.  I came across a solution using EEPROMS configured to work as EPROMS. This had potential, but I faced the same issue as problem 1, as well as using a lot of space on a circuit board.

I am keen to find solutions to these problems, so please let me know if this question is too vague!! I can provide dropbox links to the Arduino code or circuit schematic if this is useful (and allowed!) I didn't want to violate terms of use accidentally.

update:

Thank you all for your answers and help.

I will go forward with embedding an Arduino Nano into the mechanism for the next prototype.

The reliability issues are currently being caused because the Arduino Uno and screen are in the form of a handheld reader, rather than inside the mechanism. This was bought before I started on this project http://hobbycomponents.com/boards/269-uno-enclosure-kit-r3-revision-3-arduino-compatible-uno-1602-serial-lcd-module-and-case

I agree that this can be solved with a micro approach rather than with counter ICs


texts:
I am currently in the process of building an RFID access system for my house + car. I've worked out the software side (I am using an arduino) but am having difficulty with the hardware side. I bought one of these for the transmitter but the read range is terrible - the access dongle has to be touching it for it to register.

I'm thinking about cutting the traces on the card and building a new antenna to amplify the read range. Unfortunately I don't know how to do this. I've read through the antenna cookbook and the antenna design notes from TI, but I'm a hobbyist and a lot of it seemed very general and went over my head - it would be great if I could get a more prescriptive answer.

I would like to have the antenna read from 5-10cm in most orientations if possible.

How important is material choice (wire/tape/tube)?
Do I need an additional power supply on the antenna end or is the 5V from arduino enough?
Can I build a square antenna into the flashing around the card window or will the metal create too much interference?


texts:
I have pieced together a bunch of cheap hardware to control my pool.  That said, I'm at the point where I need to share a few GPIOs with external devices.  Notably, I need VCC/GND to be split numerous times and a few of the devices are on I2C so I also need to share 2 more pins.  What are my best options to do this for a relatively maintenance free solution?
I saw that a company sells an I2C bus, but I can't seem to figure out what kind of connector it uses making it hard to crimp any cables with that interface.
Currently, I'm using some simple electric cones, but I'm not happy with that.  The wires are so small that the connections are not stable.
I could create a PCB, solder some terminals or connectors and crimps all of my wires, but that seems a little extreme.
I'm also looking for a cheap enclosure where I could put the connections into to safeguard them from the mains that are nearby.  Again I could custom-order everything, but it seems like it would cost an arm and a leg for no good reason.
I like the idea of crimping simple cables as that's a pretty clean solution for the wires and keeps things clean, but I couldn't really find any medium that would let me join multiple cables in one go short of making my own board (or knowing what the terminal type is).
Thoughts/ideas?


texts: How should you position two flat-wound spiral coils for the best coupling?

texts:
I created two flat wound-spiral coils (also known as bifilar coils). The transmitter coil I made with an outer diameter of 10 inches and an inductance of 3 mH. The receiver coil I used a much smaller wire diameter, so it is only 4 inches but also 3 mH. These coils will be used for charging a 12 V battery using a 15 V source on the transmitter, so there is not much room for high losses.

They are going to be transferring power through an air gap of about 2 inches. I am wondering if I should try putting one at an angle to the other to try to get the best through-put. I do not have the rest of the circuitry prepared so I cannot test by trial and error yet. Until then I was wondering if anyone could recommend the best positioning.

I have included an image to describe what I am thinking of doing. Note that in the x-direction, the distance will be 2 inches or greater (I can not get them closer).

I do not take credit for this image; I got it at the website https://www.wibotic.com/wireless-power/

Recommendations would be appreciated. Cheers.


texts:
Its been a while I took a long hiatus due to not having a scope any longer, but I finally saved up and got myself one.

I was playing around with a precision rectifier (OPA350PA) and I came across something I don't understand.

Link to datasheet: OPA350 DATASHEET

What's going on with the positive cycle? It's somehow losing voltage somewhere. To make things more confusing for me I did it on paper and the diode is open (R.B) during the positive cycle so there's no current flowing thru the resistive network thus making all the voltage at each node the same as the input. Meaning Output should be equal to input.

Two case scenarios:

Case 1:

(Orange input / Green output)

Case 2:

simulate this circuit – Schematic created using CircuitLab


texts:
How do I connect 2 of these LED drivers to Arduino?

http://www.starchips.com.tw/pdf/datasheet/SCT2024V01_03.pdf

This is what I have so far, im connecting each output to a N-channel mosfet.
Im not sure about the other pins form the datasheet.


texts:
I've designed a board with microcontroller (NXP, K64) to control i/o's. The uart port of the uC is connected to Maxim 3362 which converts the signal to RS485 half duplex communication. Using modbus protocol in the uController, the communication flows towards the connector on the right in the scheme, from there to an outside rs-485 to USB dongle (which connects to a master PC).

I'm experiencing communication problems and using a differential probe and oscilloscope to sample the Rx and Tx lines of the differential rs485 communication (at the board output connector, pins 4 and 5 in the drawing) I've seen the following picture:

The picture shows a message sent from the PC to the uController, before the uCOntroller answered - and answered wrongly (with RTS high, as expected).

As you can see inside the message sent there are one's and zero's. The zero logic has a lot of oscillating noise on it and the one logic seems quiet.

Furthermore, before the message starts the zero seems okay. This seems a bit strange because if the ground had noise on it I would have suspected that zero logic inside the message and the zero logic before the message starts would have noise (also '1' would have noise, I guess) and not the zero logic inside the message alone...

Furthermore, I had one time during all my experiments which it did worked as expected (it was working ok for few days until now), see the following:

As you can see in the second picture the '0' and the '1' seems okay and these pictures are from the same board.

is this a board problem, component problem?

I'm guessing it does not concern with the firmware...
Any ideas?


texts: I have a circuit from a dehumidifier. It has a db107s bridge on it. I tested the ac voltage in @240v but the output is dc @335v - is this normal or could it have something else connected which is boosting voltage as I tested it on the board?


texts: 0.1" Header Cable Connector w/ Male Pins

texts:
I have a Digilent chipKIT Pro MX7 microcontroller development board. The majority of the boards I/O is through what Digilent calls a "Pmod" connector. What they really are is just 2x6 headers with a 0.1" pitch.

However, the connectors on the board are sockets. I'd like to connect things to this board through cable assemblies, I'm having a surprisingly difficult time finding a mating connector for these. I've found many housings, but they all say they're for female socket contacts and not male pin contacts.

It feels like things would be vastly easier if they had put male headers on the board, but it is what it is.

Is this kind of connector without a shroud something that actually exists? Or would I have to make some ugly workaround using a board mount connector?

(PS: I'm looking to make a cable assembly for all the pins, not use individual jumper wires)


texts:
I made a MIDI in/out circuit, which works, however, I see I have some changes compared to some other circuits I see.

In the official documentation Midi Org I see two resistors on the MIDI out circuit, both 220 ohm. I'm sure I only use one (but I'm not at home, so I cannot check which one I might miss). But so far I didn't get any problems (but never tested in a 'noisy' environment.
In the same scheme, there are 2 inverters (I think), the triangle, one without an A and one with. I also don't use that. I think it's for keeping a steady 0 or 5 V signal, so I think it's good to add. Now I see in some other circuits (randomly from google search with pics), a 74LS04, or 74LS14 or others. At home I have some 74LS14's (Schmitt Trigger hex inverter), but I also read those are for processing signals (like MIDI I guess), but can be slow. So I am not sure what to use, 7404 or 7414? I see also a lot of schemes with 7414's so I guess these are ok.
For the thru I see the same ... does one triangle without and one with A means, I need 2 inverters after each other? Probably it is. Since I want to use 3 MIDI In/Out/Thru's, would that mean 2 (per out or thru) * 2 (out + thru) * 3 (# 3 in/out/thrus) = 12 hex inverters (meaning 2 ICs?); see also item 6
In this circuit, DSS306 are used. I cannot find them on aliexpress, but also they are not in the official MIDI org circuit. Are they needed ... or better (and why)?
In this circuit, transistors are used (2N2222) ... yet another solution (?) What is the advantage? (btw, I plan using BC337's since I have those and are similar, at least if there is a clear advantage).
Also it mentions about the hex inverter, which I probably do not need for the MIDI Out (since it comes from the Arduino, not sure if the Arduino handles this), but for the MIDI Thru I want to connect it directly from the MIDI In. Is that assumption correct? (better use it for both MIDI Out and Thru?)

Thanks if you can help me with one or more of the above questions.


texts: How does this temperature alarm circuit work

texts:
Casn you please help me understand how this temperature alarm circuit works?  I am a bit over my head here, but I would very much like to understand this.

If you would like to look at the multisim file it is here: http://www.3sixty-solutions.com/mystery.zip

It is supposed to trigger alarms (red LED) for temperatures above 100F or below 50F. I have no idea how to prove this, but I can move the slider on the thermistor and see that from 34% thru 68% the green LED is activated.


texts: Why are so many pins of 8086 active-low? Does it have to do something with the fact that more circuits are able to sink current than to source current, or is there another reason for it?


texts:
When I learned, what the anode and the cathode are, there were two definitions corresponding to each other:

Cathode is, where electrons enter in the system.
Anode comes from the greek anodos meaning "going upwards", that is where current enters the system (that is the dirrection opposing to the flow of the electrons)

Now when I tried to understand the reverse biasedness of a photodiode, I struggled half an hour until I realized, that most of the sources I could find, refers the N-doped end of the diode a cathode, even if the current is now reverse.

Did I miss something? Why is that? Is there another interpretation for these notions?


texts: 10Mbps bidirectional wireless transmission with an MCU

texts:
I have a Teensy 3.6 microcontroller it has the following specs

180 MHz ARM Cortex-M4 with Floating Point Unit
1M Flash, 256K RAM, 4K EEPROM
Microcontroller Chip MK66FX1M0VMD18 (PDF link)
USB High Speed (480 Mbit/sec) Port
2 CAN Bus Ports
32 General Purpose DMA Channels
22 PWM Outputs
4 I2C Ports
11 Touch Sensing Inputs
14 Hardware Timers

I want a way to communicate with the microcontroller with a speed of 10Mbps in a short indoor range.

I have been searching a lot but could not find any helpful information. I found the following Wifi solutions but they all do not support that high amount of data.

ESP8266
ESP32
Realtek RTL8710
EMW3265

I also thought of using ENC28J60 Ethernet to SPI Header Board and connect the ethernet port to a router but not sure if will be able to get 10Mbps

I just want a simple way to communicate with the MCU remotely 10Mbps is it that difficult ?


texts:
I have a set of panel mount switches I'd like to connect - via cables - to a pcb.

The pcb won't have any components on it, it will just be a wiring loom. the concept is that having the complexity on the board will improve quality.

There's a mixture of DPDT, 3PDT and 4PDT switches, with a total of 60 connections required.

The switches I've sourced have solderlugs, like 50212LX from Switchcraft Inc.

Is there a way to achieve this other than hand soldering each connection?

many thanks in advance.


texts:
I'm having a lot of trouble with GPU coil whine (electronic buzzz).

Tested on:

4 GPUs GTX 770, GTX 970, GTX 1070, GTX 1070 Ti.
3 PSU HX620W, RM750i, EVGA 600W
3 mobos, Asrock and Gigabyte

I'm getting a lot of GPU coil whine when the GPU is under load. Buzzzzzz buzz buz buz buzzzzzz.

Buzz sample in youtube:
https://www.youtube.com/watch?v=jtXAuIJchps

The video title says how to reduce coil whine, but he just gives some software solutions (eg: enable v-sync), not good enough. No technical info.

Who is to Blame? GPU manufacturers or bad energy supply by the PSU? The buzz comes (almost) certainly from the GPU.


texts:
I'm new here - computers are my thing, but I could use some electrics help. I have travelled to a small island where I will be for several months.

I managed to bring everything except one power adapter.

I do have something "similar" and want to ask if this will work before blowing myself up.

The power requirement on the device is 12V 1.5A positive center.

I have an adapter that works on local current. It's output is 12V 1A. (12VA). Any chance this will work?

And, just in case, which way is the diagram for positive center?

Many thanks


texts: HZX D882 transistor not blocking 12V DC current

texts:
I am not too savvy with electronics so I apologize in advance for any major ignorance on my part. I am trying to use a transistor (listed in the title) as a digital switch for my Raspberry Pi 4 to control. Here is the circuit diagram.

Here is a picture of how I hooked up the circuit:

I inserted an LED in the circuit (the 5mm one that comes with an Arduino board) and it is always on. I am using an adapter that I found laying around as the power source. It reads 12V, 1.5A on the back. I would like to only have the LED turn on when the base terminal is given the proper voltage. The LED should be off when the Raspberry Pi is not providing any power to the circuit. Am I not understanding something? Should I be using different resistors? Thank you for any help!


texts: Is it safe to limit current and increase voltage above VF for LED

texts:
I am designing high power LED Driver.
I want to know that if I limit output current as required by a specific LED and my voltage is significantly greater than VF will it be safe for the LED extended operation time.

For example for http://www.cree.com/led-components/products/components/xlamp-cxa1512 LED module if my voltage is 60V and I limit the current thought my driver to 1A.

Will this be a durable design? if not why?

Thanks


texts: Circuit Representation of an Unknown Switching Transformer (Including Dot Notation)

texts:
Is there a way to identify the phase of the transformer's coils without having to see its waveform in an oscilloscope?

For example, I have this unknown switching transformer

The only thing I know is the continuity between its pins, this is by measuring continuity with a Digital Multimeter

and the inductance between each pin by measuring it with a transistor tester

1,4,5 Pins

1-4 = 0.24 mH / 1.0 Ohms
1-5 = 0.8 mH / 1.8 Ohms
4-5 = 0.17 mH / 1.1 Ohms

2,3 Pins

2-3 = 1.24 uH / 0.5 Ohms

6,7,8,9 Pins

6-7 = ...     / 0.4 Ohms
6-8 = 1.24 uH / 0.4 Ohms
6-9 = 1.24 uH / 0.4 Ohms
7-8 = ...     / 0.4 Ohms
7-9 = 1.24 uH / 0.4 Ohms
8-9 = ...     / 0.4 Ohms

How do I know what is the direction of the windings? How do I know what would be its equivalent circuit representation?


texts:
How can I convert a 113B13 transformer to a center tap transformer? Is like this, for example:
- primary coil: 1 and 2 pins.
- secondary: 3 and 6, where 4 and/or 5 is the center tap?
Will this work?


texts: Soldering Iron and Electrostatic Bracelet Connection

texts:
I have a DIY soldering station and I want to ground the soldering iron and I also want to use a electrostatic bracelet connector for the soldering station.
Can you please help me how to connect the soldering iron's ground to the ground and how to connect the electrostatic bracelet to the ground of the soldering station ? I know that there have to be a resistor, but I do not know how to connect that resistor...


texts: Why reactive components have less influence at low frequencies?

texts:
Some textbooks state that reactive components (may) have less influence at low frequencies, since inductance and capacitance are generally more significant at hifh freqs. "Pratical electronics for inventors" is one of them.
I don't understand this statement, since capacitive reactance is inversly proportinal to frequency.
How should such a statement be interpreted? I suppose it assumes something from practical experience, but I'm not able to figure it out.
EDIT: The context of the statement was input and output impedence. From your answers I understand is that from the point of view of a low freq signal entering, or exiting, a circuit the relationship between parasitic impedence and capacitance is more relevant then the overall capacitance (which should increase with low freq).


texts: How do I switch an 18V LED circuit on/off with the signal from my amp to my speakers?

texts: I have an LED strip in my Peavey 6505+ guitar amp and would like it to only illuminate when I play my guitar. I could get 4 LEDs to light up well by just wiring them in to a 1/4" jack from the output of my amp. It worked great. It did not have enough power to supply the entire 30 LED strip. They worked, but were very dim. I now have the LEDs wired to a spare 18V output from my power source, and am wondering if there is a switch that will activate the powered LEDs with the output from my amp. Any help would be appreciated.


texts: SGMII Termination - Not understanding recommendation

texts:
I am going to be using a processor that has a few SGMII interfaces. From what I understand, these interfaces have LVDS logic levels. I am not use to seeing the termination scheme as recommended below.

I thought the 100 ohm resistor should be near the output and not near the input
Not sure what the 50 ohms to GND does after the ac coupling caps.

Any ideas?
Thanks!


texts:
Our project has one CC1101 transmitter sending signals to several CC1101 receivers. The transmitter sends signal to the first receiver, waits a couple of seconds before sending signal to second receiver, waits another couple of seconds before signalling to third receiver, and so on. After a while it then re-starts the signalling sequence.
The problem we have is that sometimes the signal is not received by a receiver as expected, this happens more as the distance is increased. The distances are not very long, but all boards are very close to the ground.
The problem isn't that a signal is never received, which would be easy to accept, but rather that it is sometimes not received. The same receiver gets a signal one time but not another time. Similarly, one receiver may not get a signal but the next one does.
Any pointers on what the problem could be?  Is this likely to be poor hardware design or incorrect firmware settings?
Thanks


texts: Current sign when leave from battery and entering in resistor

texts:
I have to some confusion relate to basic fundamentals of current sign.
Here is the simple circuit, with 30v, 1k resistor and current is 30mA.

Whenever i have connected current prob to the battery positive terminal then in waveform current is shown -30mA(minus sign)

Whenever i have to connect current prob at the first terminal of battery then output waveform show the +30mA(plus sign)

My question is battery + terminal and resistor first terminal both are connected with the same wire. so why output waveform is different

Thank you


texts: How to calculate bit time of any signal?

texts:
Given a data rate or clock rate, how to calculate bit time of any signal/interface?

As per what I know, bit time = 1/data rate. Is it correct?

I got a little confused when I could not calculate the TBIT values (and eventually skew) in the following:

  This time difference, also known as intra-pair skew, is specified by
  HDMI for a receiver with 0.4 · TBIT for a TMDS clock rate of 225 MHz,
  which translates to 178 ps maximum. For an HDMI transmitter the
  specification calls for 0.15 · TBIT for a TMDS clock rate of 225 MHz,
  which translates to 66 ps maximum.

Source: https://e2e.ti.com/cfs-file/__key/telligent-evolution-components-attachments/00-138-01-00-00-10-65-80/Texas-Instruments-HDMI-Design-Guide.pdf

Am I missing something here?

Any help is appreciated.


texts:
Is using twisted pair for the supply in a long cable a good idea?
The cable contains two twisted pairs; one twisted pair for CAN Bus, and the other twisted pair would be used for GND / Supply.

What would be the effects of using such a cable? Good / Bad?


texts: Why are shorter leads preferred over longer leads?

texts: I'm building oscillator circuits on a copper plate for an RF design class using the dead-bug method. I know that short leads between components is preferred over long leads, but why is this? I heard the term "inductive loops" being referred to as an unwanted effect that happens with longer leads. I don't understand what this is though. Does it have to do with propagation delay?


texts: Design of the two stage amplifier with p-type input

texts:
I have to design the two stage amplifier with p-type input (p-type diff pair), the schematic bellow:

However, mostly tutorials discuss the same architecture but with n-type input.

My main questions: Can I use tutorials with the n-type input stage amplifier for designing my amplifier with the p-type input stage?

Secondly, can you recommend papers there design of the "p-type" architecture is shown, which I can use for my design?

Lastly, what is the difference between these two architectures?(in general)

Regards,
Paddy


texts:
How do I connect this three speed motor directly to the electrical mains?

The second image is the capacitor connected to the red and brown shown in the first image.

There are 4 wires connected to the motor coloured white, yellow ,blue and black respectively. White wire has a high speed label. Yellow has a medium speed label and blue has a low speed label.

This is the schematic from the manual of the fan which I salvage this motor from.

I have no knowledge about motors. Hope someone can enlighten me on the:

Type of motor that this is and,
How to connect it directly to the electrical main?


texts: What is the difference in the input from inbuilt microphone and an external microphone amplifier?

texts:
I wrote a MATLAB script interfacing my laptop's inbuilt microphone to calculate the dbA levels of noise in my classroom. (un-calibrated, as of now)

I want to now use this dbA calculation script on data from my arduino. (Electret Microphone Amplifier 4466).
I want know what is the difference in the 2 inputs and what changes I should make in acquiring my data from the arduino to receive the same result as I did with the inbuilt microphone.


texts: Debugging when oscilloscope grounds cures the problem

texts:
In a nutshell :

My circuit behaves erratically
I connect the 'scope to find out why
The problem disappears

In particular, this concerns the circuit in my last question although this is not the first time it's happened to me and I'd like to know what's the correct way of finding the source of this general problem. In software, we'd call these Heisenbugs but I don't know if the same pun is used for EE problems.

In this particular instance, I have a test program running on the PIC that goes from 0% to 100% duty cycle on the PWM output in 8 steps, pausing for 10 seconds at each step. Then it goes back down again from 100% to 0%. The problem is that it goes up ok, but gets stuck coming down - i.e. the fan doesn't fall in speed as it should.

Just connecting the ground of the probe to my circuit ground fixes the problem, even without the scope switched on. When the scope is connected and running, all probed signals look clean and tidy and everything works perfectly.

I'm guessing that I'm picking up some interference from mains hum or from the power supply, but without being able to observe it when it's misbehaving, I don't know what it is I should be fixing.

What do I do next?

Schematic:

Board:

The 2x5 header at the bottom is there just to expose all of my unused PIC pins in case I want to extend this in future (it's a hobby project). Fan connector is at the top.


texts: Is this analog switch good for UART lines?

texts:
Currently designing a circuit to switch between two UART lines using an analog dpdt switch. Been searching for a while and found the BL1532. The datasheet says it's a DPDT USB2.0 Analog Switch, but not sure if this chip will work for UART since USB is pretty fast (not an expert in this field).
Here is my circuit:

The MCU can communicate from 9600 to 115200 baud rate.
As you can see I drive the BL1532 select pin with an spdt switch for 3.3V HIGH and GND LOW. Any advice or opinion is appreciated


texts: How to extract ADS marker information to matlab?

texts:
I am new to ADS software and I want to extract marker values to MATLAB.
Is there any efficient way to do that? For example,


texts:
I'm in the middle of a "living room acceptable" project, and I'm looking to capture the spirit of a 1970s preamplifier (Quad 34, see below). My design has 6 LEDs, 4 push buttons, a latching mains button, and a rotary encoder. The rotary encoder has a threaded attachment, but this would only provide attachment at one side of the board. My original plan was to make a PCB with the front panel controls, and then use adhesive standoffs, but I don't think that the adhesive will sustain button presses over time.

My question is how to attach the front panel controls securely, but without visible screw mounts on the front panel itself. I'm using a Hifi2000 case (picture below), which is not drilled on the bottom panel. The front panel is 4mm thick aluminium, and comes blank (aside from the countersunk corner holes).  I don't have the tools to blind tap holes just, although this might a good time to pick them up if that's the accepted view.

Thanks in advance!


texts: Difference between cordic algorithm and table based methods for elementary functions computation

texts: In this book both Table Based methods and Cordic iterations are explained. computationally speaking i suppose the Table based is usually faster, even though it probably requires more resource, while Cordic is probably slower, but probably less resource consuming (if my understanding is correct, it should be a specific instance of shift and adds algorithm). But are there other benefits/drawback in both approach? I suppose also the CORDIC doesn't suffer of the table maker dilemma, even though it in general requires a LUT.


texts: How can I cause my oscilloscope to trig on interruption of AC voltage?

texts:
I'm probing a point with 230V RMS voltage inside a machine (don't worry, I'm using a 100:1 CAT 3 probe rated at 600V), and would like to trigger my oscilloscope at the point when this signal is interrupted. That is, the sine wave ends and becomes a flat line.

I have a Rigol DS1054Z oscilloscope. Is there some clever way to arrange such a trigger? I thought perhaps I could use the slope trigger, but I didn't get it to work.


texts: We have 2 variants of device which differ only by battery. Shall we pass FCC separate FCC certification for every of them?

texts:
We developed a BT4LE device which is being shipped in two variants. They are the same except for battery variant.

Is it possible for us to pass one FCC certification so that it is valid for both device variants? Are there any items to be careful about?


texts: Infinitely expandable binary decoder circuit

texts: I tried to make some binary to decimal decoders, but I had no idea how to build them, so I ended up using the "combination checker" (basically providing one checker for each number). That was really inefficent and almost impossible when decoding e. g. 32-bit numbers (4,294,967,295 combinations). So I want to ask, is there some logic pattern you build over and over? Or should I make a separate arithmetic unit for calculating  this the mathematical way? I want my output to be for example 7 segment display. And one more question, how does this decoding work on normal computers? Thanks for help


texts: How to find a specific component in Altium PCB

texts: When viewing a PCB (.pcbdoc) layout in Altium, is there a way to search for a specific component by name?  Like "highlight C35 and show it on the screen"?


texts:
I am attempting to implement a tachometer interface that will accept digital pulses as an input. I simply count clk rising edges (50Mhz) between each rising edge of the tacho pulses (1Mhz). I have found examples on the web that achieve what I need to do, but in an attempt to not make the same mistakes in the future I would like to understand why this solution doesn't work.

When I say doesn't work I mean post-synthesis functional simulation doesn't produce the results I would expect. The behavioral simulation does output the values I was expecting.

In summary, synthesis appears to be ignoring my attempt to reset a variable to 0 (see comment 'this does not appear to execute' below). The tacho_count output increments without resetting. See simulation plots below.

entity tacho_interface is
    Generic (
        FREQ_DIVISOR : integer := 6;
        MIN_RPM : integer := 200
    );
    Port (
        enable : in STD_LOGIC;
        clk : in STD_LOGIC;
        pump_tacho : in STD_LOGIC;
        tacho_count : out STD_LOGIC_VECTOR(31 downto 0);
        error: out STD_LOGIC := '0'
    );
end tacho_interface;

architecture Behavioral of tacho_interface is
begin

process
variable last_tacho : std_logic := '1';
variable tracking_cntr : integer := 0;
begin
    if (clk'event and clk = '1') then
        if (pump_tacho = '1' and pump_tacho /= last_tacho) then
            tacho_count <= std_logic_vector(to_unsigned(tracking_cntr * FREQ_DIVISOR, tacho_count'length));
            wait for 0ns;
            tracking_cntr := 0; --this does not execute
        end if;
        last_tacho := pump_tacho;
        tracking_cntr := tracking_cntr + 1;
    end if;
    wait on clk;
end process;

end Behavioral;

Post-Synthesis Simulation illustrating problem
(accumulation without reset to 0)

Behavioral Simulation illustrating what I expected


texts:
I am studying this little IC called MBI5168. It is serial-to-parallel LED driver.

I don't get why OUT0, OUT1, and OUT7 are ON, when the 8 bit data latched in SDI shows 10100011b. Shouldn't this yield OUT0, OUT2, OUT6 and OUT7?


texts:
I am looking at some SMA connectors. Now, I am using mostly 75 Ohm SMA connectors. Most of the connectors (cable mount) are 50Ohms. So, wat exactly is the difference between these 2 connectors. Apart from the impedance factor, how is the impedance controlled to make it 50 or 75 ohms ?
Is it some special coat or the compound used ? Can anyone explain it please ?


texts: Balanced to unbalanced circuit not working correctly?

texts:
I've tried to build a balanced to unbalanced signal converter with an TL072. The problem is that if I put a balanced sine signal into it I only get the bottom half of the sine as unbalanced signal out of the circuit. That’s not how it should work.
The circuit I am using is this circuit:

Is there any way to solve this problem?
Thanks in advance.
EDIT:
The problem was, I was using +30V but because in this schematic the OP-Amp is used in differential mode it requires +/-15V.


texts: Could a HM-10 be powered by a LiPo with LDO?

texts:
The HM-10 BLE module has a VDD range of 2V-3.7V. A fully charged 18650 could be 4.2V (even 4.4V?). Could a HM-10 be powered straight off a 18650? Are modules typically designed to run directly off a LiPo without a LDO?

Thanks


texts: How to place decoupling Capacitors in a star ground design?

texts:
I am in the process of routing a star-grounded amplifier pcb and wondered on how to connect the decoupling capacitors. As I see it I have two choices:

Connect the ground of the capacitors directly to the star-ground point.
Connect the ground of the capacitors "in series" between the star-ground point and the GND of the amplifier.

Basically:

simulate this circuit – Schematic created using CircuitLab


texts: Driving 259mA stepper motor with a 2N4401

texts:
A while ago I asked a question about driving a stepper motor using a 2N5550 and was advised that it wasn't really capable/a good idea. I received a good answer but would like a bit more information really so that I can make these decisions for myself in the future.

2N5550

So on the 2N5550 transistors data sheet it says it can drive up to 600mA (DC) under the maximum ratings (am I interpreting this correctly?):

If this is correct, why does the DC Current gain graph only show up to 100mA, is this just because it can handle 600mA but would be almost pointless to actually use it for that because of the low gain at that level?

2N4401

So this brings me to the 2N4401. The datasheet for the 2N4401 also says the max collector current can be 600mA (again, am I interpreting this correctly?).

Now the current gain graph on this transistor shows it going up to 300mA however it says "pulsed" in the title of the graph and there doesn't seem to be a graph for continuous so I'm a little confused why this might be? I suppose driving a stepper motor would come under the category of pulsed though?

So assuming that this is suitable for driving my 259mA stepper motor I would need to supply the base with about (259/150) 1.7mA (259 being the number of mA needed by the stepper motor and 150 being roughly the current gain (derived from the graph)?), is this correct?

I understand that from my other question I should really use a MOSFET as they are better suited to the job, I just have a handful of these 2N4401s kicking about that I thought I could test my code and theory with.

Thanks in advance and I'd appreciate a response to even the little questions I raised like the "am I interpreting this correctly?" ones, just to reassure me that I'm on the right lines (or not).


texts: Adjustable power supply simulator/reality

texts:
Hi im a student of computer engineering and im currently doing a project of a adjustable power supply it should be doing 0-30V but im getting some problems with the word adjustable haha,i got this circuit, it takes away every part of the PS that does not work with the adjust of the voltage.

On proteus this circuit runs fine, my teacher gave a circuit and there was some flaws, i searched on books for similar circuits because im tied to the components that i have, so more complex circuit and other components are not an option.

The simulation runs ok, RV1 does the main adjustment and RV2 the fine, but i cannot get this circuit to work on real life, im using a linear power supply to test and i get some short circuit protection to work some times, the circuit on the protoboard is just as on proteus, revised by tree people, there is no shorts or any mistake.

Is there anything that i am missing here? Im going by what proteus tells me on the simulation with some probes and other simulation tools, maybe this is the mistake.h


texts:
I'm creating a simple vibration mat for a child which will be triggered by a force sensor. I'm not trying to do anything complex (like changing frequency of vibration) - simply an on/off circuit. What I'd love to get some advice on, is suggestions for wiring up and powering what will be a large group of motors...

I've picked up a bunch of generic iPhone vibration motors from eBay that happily run on a 1.5v battery on their own. However, I would like to run them in groups of 9. Because I'd like to run the group at the same speed, I assume that wiring them in parallel would be the way to go, but do I need to be wary of how much current is being drawn, or other tricks when grouping multiple motors?

Finally, if I can I would like to have the mat run on battery power if possible - particularly as it will be used by a small child. Is this realistic for so many (albeit small) motors?


texts:
In this Maxim appnote the avalanche noise of a zener diode is amplified by two cascaded LNAs (Low-Noise Amplifiers):

You can guess what my question is: why use low-noise amplifiers if you want noise in the first place? Don't ordinary opamps produce white noise?


texts: charging circuit for series coin batteries

texts:
I am designing a circuit that will be powered by two rechargable coin cells in series, and I need to include a module to recharge them in-situ.

I have had a look on RS at the range of rechargable coin cells and it seems that there are two variations with regards to the chemistry; Lithium Vanadium Pentoxide and NiMH.

I am trying to determine suitable charging circuits for both types of batteries, bearing in mind that there are two cells in series. I am having trouble finding any example charging circuits, particularly for the Lithium Vanadium Pentoxide battery, which I am most concerned about as I know some types of Lithium battery require specific charging cycles.

What do these batteries require from a charging circuit?

Are there any things that must be avoided when charging these batteries?

Can you reference example charging circuits and/or charging IC's for these batteries?

Cheers!

Extension:
I have also found lithium-ion coin cells that have a nominal voltage of 3V.

Please can you advice me how to design a charging circuit for a pair of these in series?


texts: Minimizing mosfet interactions and overshoots. A case study

texts:
I'm back again with another headache of my own creation.  It seems I'm constantly learning things the hard way.

Straight to the point questions:

I've noticed that my reverse voltage protection mosfet interacts with another p-mosfet switch in a bad way (yikes!).  Does making the mosfets identical help with this interaction / do I want the switch to be more / less capacitive than the other?
I've made four copies of this design.  One "works" and the others (that are in my opinion much more cleany routed) don't.  Can sloppiness in soldering ever contribute to system performance?
Are there any easy ways to tell if a microcontroller is browning out vs resetting? (I'm thinking just scope the reset line / add a cap and see if it goes away?)

How I got here:

I'm making microcontroller switch boards.  The design utilizes three mosfets:
1:  Reverse voltage protection (p-mosfet)
2/3:  n-mosfet / p-mosfet pair to turn on a 12V rail.

Here is the full diagram of the circuit:

It seems like a simple circuit! I have used this type of circuit all the time (minus the reverse voltage protection).  I figured everything would be aok.  I constructed one, and it worked as expected.  All good, right?  So I made three more.  None of the new ones work.  The microcontroller resets when the switch is thrown (brownout?).  After some head scratching I got out the oscilloscope and attached the leads to the 12V rails after each mosfet, the 3v3 rail after the first regulator, and the flip signal to the n-mosfet gate:

Looks innocent enough.  ENHANCE!

Uh oh.  Is that a wiggle?  ENHANCE!

Great.  So I have a HUGE ripple going through my system.  That needs to get fixed, right? I'm assuming this is part of the problem. (4V overshoot on the 12V... and a 3v3 ramping to 5v5... ouch).  The 5.5v might significant because the microcontroller is rated for 1.8-5.5V?  I know the controller shuts down if it's below 2v7.  I'll change the brown-out level and see if that helps, but figure I should address the ripples head on.

I've researched the options.
1.  Put a cap on my reset line (2V might be reading as logic low?)

Put larger caps on v_out for regulators.  Currently I have the recommended 2uF, but it's not looking like it's enough?
Slow down the turn-on:

I plan on going with swapping the n-mosfet with a transistor (and maybe an rc circuit to drive as well).  It's a battery operated circuit, so I'd like to save current (hence the n-mosfet).  I'll watch the spec's for the mosfets to make sure I don't fry them on the way up, but this is a once/day thing so they have plenty of time to cool.  Are there any tips / things I'm overlooking?

Also one other thing:
The first circuit I built has WORSE swings (on the 12V rail) but seems to hold it's own / doesn't reset.  I'm unsure of whether the reset is because of brownout, or because of the reset switch (I will add those pictures soon).  The reset area is a little bit of a maze, so maybe the capacitance of the wiring is helping out? Any thoughts on this?

Many many thanks as always.
Matt

UPDATE:
Sure enough, sometimes you gotta slow down.  I'll let the data speak for itself:

I put a 100k resistor on the gate of the large mosfet.  Slowing that down prevented squeezing the system all at once.  Great response.  Clear as night and day.  I'm going to get started on chapter 2 of horowitz.  Really should get a solid grasp on this stuff. Thanks jp!


texts: Methods of measuring speed of anemometer

texts:
I enjoy DIY, but to keep things simple I purchased an anemometer cupset (3 cups). I feel that a magnetic reed switch would get "bounce" at higher speeds and I was thinking of a disk with a slot, and sensing with an LED/photoresistor pair. Would the photoresistor be fast enough? Or would I need something like a phototransistor? Are there even better ways while keeping with the KISS (Keep it simple stupid) principle?Also, how do I convert rotation pulses into MPH?
Note: I live in Florida and as long as my tower (20 feet tall) stands, I might be recording hurricane force winds.


texts: Triac doesn't triggering when the power jack pins switched?

texts:
I built a power circuit with MOC3063 & BTA40600 for controlling heating element (2000 watts) according to the image. when I plug the jack in let's say one direction the circuit works like a charm ... but when I change the position of the jack (means Neutral & Phase) the triac doesn't work at all!
Where is the problem? any help would be helpful
regards


texts:
I understand from a training session that ProfiBUS is considered intrinsically safe, while ProfiNET is not. Some googling indicates that ProfiNET can never be intrinsically safe, because Ethernet can not be. This surprises me, as Ethernet over fiber seems very unlikely to cause a spark under any imaginable circumstances, and Ethernet over twisted pair shouldn't be much worse in this regard. We're not talking about high voltages or power availability.

So why is Ethernet not considered intrinsically safe, while other low-voltage communication standards like ProfiBUS are?


texts:
I have a problem regarding the schematic from the link below.

I made the schematic from this link, at figure 5:http://www.nutsvolts.com/magazine/article/light-sensitive-circuits

The problem is that when the light descreases there is a level of light when the relay is turning ON and OFF at a very high speed.
I tried to repair this by increasing the 1M resistor to 4.7M, but it does not solve the problem.
I saw that there is an operational amplifier with positive feedback (hysterezis), so I tought that modifying the value of 1M resistor could solve the problem by modifying the value at which the AO is turning ON.

What can be done to eliminate the fast switching between ON and OFF of the relay ?


texts: How to make a LED flash twice every second?

texts:
I know that I can make a LED flash using a 555 timer. How may I make it flash twice every second?

What I am trying to do is to make the LED flashes two times, then wait a second, and then flashes two times again. In pesudo code is something like this:

while (1) {
    LED_BLINK_ONCE();
    wait(10ms);
    LED_BLINK_ONCE();
    wait(1000ms);
}


texts: Replacing torch/flashlight battery with power adapter

texts:
I own a torch/flashlight which requires a 26650 2000mAh rechargeable battery.

I'd like to power it with a power adapter, but all I can find here is 3V or 4.5V so it's either too low or too high.

EDIT: 26650 rechargeable battery is 3,6V - 3,7V


texts: Using a PGA to scale input voltage ranges?

texts:
I have a current design of a circuit which works well, but I am needing to make a few extensions to it. I am working on a 4 channel oscilloscope. Each channel must be able to take various ranges of input and properly scale it to 0 - 3.3 V for a ADC to process with the best accuracy.

AC signals will be between 0 - 100 kHz with the setup for the following input ranges:

+/- 10V range
+/- 5V Range
+/- 1V Range
+/- 0.5V Range

I already have a working differential op amp circuit design for +/-10V (ATTACHED BELOW) but I need to be able to scale the remaining ranges as well using a programmable gain amplifier instead of multiple resistors and mux combinations on my differential amplifier.

Any advice would be greatly appreciated!


texts: Transistor amplifier with active load in high frequencies

texts:
I have simple transistor amplifier with active load, problem is I am using the circuit in 1 to 10 MHz range, so as you can see the gain is low in this region. Used transistors are bc337 and bc327. I do need gain around 800.

So my question is:

Should I use these transistors and chain more stages to archive desired gain.

--or--

Should I use another type of transistors with higher maximum frequency. If yes what kind of?

The key factor is price.


texts: Technology for precise distance measure?

texts:
I want to create a system that's able to scan the environment around him and create a depth image of what's around it, like this image, where the color lightness is inversly proportional to the object distance, in this case cans.

I saw some infrared modules that will do the trick, but the distance it's too low for what I want (100cm top), and I prefer something that will have a range of 1m-10m. Is there any kind of technology that will do the trick?

The final goal it's to detect objects that could be far, so I need some precision both on short and long range.


texts: What source I should learn about DDR3/4 signalling and PCB layout?

texts: Please suggest a comprehensive source to learn aout DDR3/4 schematic design, selection and PCB layout. It would be good if it is related to use of DDR in embedded system.


texts: I have created a sub-circuit in Proteus but I can reuse it? How do I reuse it?

texts: Basically I want to pack a large number of components to form a small device. I will use this device many times. So I created a subcircuit and designed my circuit in it. But whenever I make a copy of it. It doesn't work. I read some stuff but it doesn't seems to solve the problem. How do I reuse my subcircuit?


texts: Repairing power circuit with reverse polarity damage

texts:
Recently I bought an old musical keyboard (a Casio HT-3000). It came with a PSU, and when it arrived I plugged it in without paying too much attention, and... nothing but a burning smell. I quickly unplug and look at PSU ... seems they sent me the right voltage, but wrong polarity (Casio had -ve on the centre pin of their power supplies at that time).

I've found the schematics, and inspected the board.  From inspection it's obvious that transistor T4 was the source of the burning smell, so that obviously needs to be replaced.  Not sure if there is anything else fried less-obviously.

T4 is a 2SA1286H.  Now I've found a vendor for a 2SA1286 (datasheet), but can't find  the h version.  As far as I can tell, the H version had a higher hFE (1200, as compared to 400-800 in the non-h version).

Will the non-h version of this transistor suffice as a replacement (I assume not).  If not, what could I use instead?
What is the purpose of T4 in this circuit?
Does it look likely that other components will have been damaged?

Thank you for any help.

Unhappy transistor

Schematic (x marks T4)


texts:
I'm having trouble understanding the max voltage input voltage range for an I/O pin on a stm32F11 when powering it with 3.3V.I'm want my STM32 to communicate with a 3.3V input signal and need to know if the GPIO and rx/tx UART lines are 3.3V tolerant. Looking over the absolute max specs in the data sheet it looks like they are rated to 4V? I expected to see a table that specifically listed GPIO pins, not "any other pin":

https://www.digikey.com/product-detail/en/stmicroelectronics/STM32F411RET6/497-14909-ND/4935722


texts: Trying to Understand Spurious Sideband Interference (and some causality problems...)

texts:
Suppose I have a radio and I intend to transmit a 0.1 µs pulse on a 100 MHz carrier.  Fourier theory tells me that this signal will produce some sideband interference resembling a Sinc function.

Suppose I have a friend Bob who is using an adjacent carrier.  These spurious sidebands will be received as interference for him.

However, if I decide to lengthen that pulse to 0.2 µs, the sidebands get "squished in."

As a result, Bob hears a lot less interference.  Here is where things start to get less intuitive for me.

When does Bob start to hear the interference?  My gut instinct says he will notice interference at the very start of the pulse.  However, Bob cannot see into the future, so he cannot know how long my pulse is.  And if he doesn't know how long my pulse is, he can't know how much interference is resulting.

I am forced to conclude that the interference does not formally "exist" until the very end of my transmission.  However, this seems to go against experience and intuition.  Is there a better explanation for all of this?  Maybe some time-frequency analysis might explain things better, but I am still at a loss here.


texts:
as the title said, I'm facing this problem.
I'm controlling a Peltier element (91.5W at 15V, what should give us aprox. 4A at 12V) with two different MOSFETs: IRF3205 (Rds(on) = 8 mOhm) and FQP30N06 (20mOhm). Using the formula Tjunction = Rja * (Rds_on * 4A²) + Tambient, the second MOSFET should raise its temperature to 45°C at 4A, but in real life, it's getting very, very warm. As my multimeter isn't reliable for measuring current, I decided to put a 0.235R resistor between Source and Vss for measuring current by the voltage drop across the resistor, and got 0.8V, which means aprox. 3.4A, and guess what? The MOSFET doesn't heat up as much as before: with the Current Sensing Resistor, the heat dissipated is what it should be by the formula.
My question is: why the MOSFET gets so hot without the 0.235R resistor?
Before you ask, the MOSFET is full on (gate connected to 12V by a 3k9 resistor. No PWM or something like that. It's always on). And yes, the IRF3205 gets hot too.


texts:
I'm looking for a solution to control the direction of a powerful DC Motor. I came up with the idea to use a H-Bridge. Since the motor uses up to 3.2A the amount of possible H-Bridges is quite limited. The supply voltage on my quad is 3.7V. Since my outputs are limited I want to control the position using only one Digital Output. Which does work in one direction if set to 0 and other direction if set to 1. The PWM output should control the velocity.
Is that even possible?

I found this one but I have absoultely no clue if this one can be controlled only with 2 inputs per motor (1 PWM , 1Digital Output).


texts: How static electricity gets build up and how it gets discharged?

texts:
I get electrocuted all the time by contacting metal object, by running a cart in the grocery store, opening the car door, touching the door knob. I have reseached various article of how static electricity is created and how it is discharged but none has satisfied me. Can someone explain it to me, how it is created?

Some thousands of voltage is generated when you walk on carpet or even on dry concrete, floor. How this charge gets accumulated continuously and never gets discharged?
Why it discharges through your fingers, when it is really built up on your shoes or clothes. If you touch you clothes with the door knob nothing happens but if you touch your finger, boom, you get shock? How does the whole process work?


texts: Does a crude Li-ion 18650 battery have internal thermal (mechanic?) protection?

texts:
For clarification: crude means "it does not have any protection circuit attached".

Short history long:
I extracted 6 18650 (Sanyo) batteries from an Acer battery pack. They had more than 3V each and accepted charge and load.
Unfortunately a pair of them stood (unused) next to the hot air output of a laptop.
When rescued from the heat they were, obviously, hot, maybe more than if they were just a piece of something else - not sure.
Hours after that they had almost no more charge (0.8V and falling) and, strangely, extremely high internal resistance (a load of 100Kohm was sufficient to turn 0.8V into 0V).
When trying to resurrect it, there was no current flowing through it, no matter how high the voltage applied (I tested only until 15V).

A normal behavior would be a low resistance after discharge. My conclusion is that something disrupted inside with heating. Does anybody know if these 18650 have such "thermal fuse"?


texts: SMT Multi-Footprint Size to IPC standards for production

texts:
I am currently designing a board that will need end up getting CE tested, and I am currently testing the effects of different sized decoupling capacitors but I am constrained on space.
I want to make a footprint that could encompass imperial IPC-7351B footprint sizes for 0805,0603, and 0402 chips. I did so, but I wanted some input on why this would be a BAD idea.

I could see that there's a chance that maybe in production, if I went with an 0402, there might be issues with tombstoning, but what else might be an issue with this?
Thanks


texts:
If I wire 2 AA cells with a nominal capacity of 2 Ah and a nominal voltage of 1.5V each in series, then I'll get 3V with 2 Ah, right?  Is that, thus 6 Wh?

If I wire them in parallel, I get 1.5V with 4 Ah?  Is that also 6 Wh?


texts: Frequency response of an ideal LC circuit

texts:
Does the frequency response of an ideal LC circuit exist? The frequency response of a system is defined as: $$\int_0^\infty{h(t)e^{-j\omega t}dt}$$ where \$h(t)\$ is the system's impulse response, but an ideal LC circuit is marginally stable, i.e. its impulse response doesn't decay or blow up as time approaches \$\infty\$, so it makes sense that the integral doesn't converge, therefore it shouldn't exist. Am I wrong?
I might be, because the frequency response is used to solve for the output of the circuit. If a sinusoidal input \$a\sin(\omega t+\theta)\$ is provided to the circuit, the forced response is equal to \$|H(j\omega)|a\sin\big(\omega t+\theta+\angle H(j\omega)\big)\$ (from this lecture), where \$H(j\omega)\$ is the frequency response. If I assume that it exists, I get the correct forced response (as if I solved it through undetermined coefficients if I instead formed a differential equation). So does/doesn't it exist?


texts: what is the diffrence between 5 VDD and 12V on this pin out diagram

texts: I have this wifi module that i pulled from my dishwasher. On the pinout directions it says 5vdd and 12v im confused on what this means. what is the input power that is needed


texts: What type of electronics soldering is this soldering flux used for?

texts:
I usually use rosin flux for soldering or one with rosin core if the solder refuses to stick. I recently found this Goot BS-15 flux, but it says not applicable to PC boards. The label says hobby use soldering paste.

Unfortunately, the contents everything on the back of the container is in Japanese so I can't know for sure what this is intended to use for.

So,has anyone here come across this type of soldering flux and know what this might be used for?


texts:
For few days I've been wondering why an std_logic_vector type can't get an unsigned/signed type.

My question is : does this constraint only comes from VHDL syntax and though this is implicitly needed by the compiler or does it have a real impact after synthesis and if so, how?

In other terms I'd like to know what are the effects of this :

signal my_slv_signal : std_logic_vector(7 downto 0);
signal my_unsigned_signal : unsigned(7 downto 0);

my_slv_signal <= std_logic_vector(my_unsigned_signal);


texts: Is it possible to add a UID to M45PE10-VMN6?

texts: Is it possible to add a UID to p/n M45PE10-VMN6 ?  We need to add this security feature to these chips, but I am assuming it needed to be done at factory.  Originally we could have purchased p/n M45PE10S-VMN6, the "S" signifying the UID.  Any ideas on whether this is possible?


texts:
I have been developing control software for below given power electronics circuit.

This circuit consists of two three phase inverters with common DC link. One
inverter supplies a three phase squirrel cage induction machine working as a motor and the second one supplies also three phase squirrel cage induction machine but working as a generator. Both induction machines are coupled together via sheaves and belt. The common DC link is connected to utility grid via three phase diode rectifier.

Both inverters are controlled by one microcontroller. The sequencing should be
following. At first the precharging step is needed. After that step the average
DC link voltage value is 3*sqrt(6)*230/pi V. Then the motor is started with scalar control algorithm in open loop until the prescribed frequency is achieved. After that the second machine should be started.

The second machine should work as an induction generator. So it is necessary to
somehow identify the desired stator frequency so that the machine will actually
work as a generator (the synchronous speed must be lower than the actual
mechanical speed which is prescribed by the motor).

My problem is in the generator inverter control. I am not sure whether I
understand the "physics" correctly. The generator rotor is rotated by the motor.
As soon as I set some value of synchronous speed (i.e. stator frequency) so that
the generator mode is achieved the generator will start deliver electrical energy into the DC link. This results in current flowing from the generator into the DC link capacitor via freewheeling diodes in the generator inverter. This results in rise of the DC link voltage. As soon as the DC link voltage achieve the voltage produced by the generator and the current cannot flow and the generator stops deliver the energy. So I need DC link voltage controller which will control the DC link voltage by changing the generator synchronous speed (i.e. delivered power by the generator). The problem is that the DC link voltage is also influenced by diode rectifier wich isn't controllable by the DC link voltage controller. Please can anybody tell me whether my thinking is correct and whether it is possible to control this circuit with DC link voltage controller and what conditions must be fullfilled? Thanks for any suggestions.


texts:
I have a slide potentiometer for a volume switch that I suspect is failed. I diagramed out the connections in the image below. The potentiometer is on the top part of the image with the outputs pins on the left, and the input pins on the right. I'm reading the following resistances between these pins from the slider pot (negative lead to output side on left of image, positive lead to input side on right of image), one measurement with the potentiometer slide all the way to the left, and the other all the way to the right which I believe is supposed to be full volume:

+Lead:-Lead    Ohms Leftmost   Ohms Rightmost
   R+:R-         11.67K          11.67K
   R+:Y          11.67K          9.9
   R+:L-         OL              OL
   R+:OR         OL              OL

   L+:R-         OL              OL
   L+:Y          OL              OL
   L+:L-         OL              OL
   L+:OR         OL              OL

If I'm not mistaken do these measurements demonstrate a fault with the left channel?

Background

I'm troubleshooting a faulty Yamaha Keyboard (CLP-550), and I've roughly traced the signal with a multimeter to the master volume switch which is a slide potentiometer. It's labeled as a Yamaha VB022400 Slide Pot.  A10KX2 RSGA2 MASTER VOLUME. I found hits on the A10KX2 ID which brings up a bunch of audio hits with mixer boards and what not so it looks like a good generic ID for the part. The left speaker's don't play audio so I'm hoping it's just this one part that failed since the signal seems to come out the main circuit board from both sides, but nothing after this volume control. Is my pin to pin resistance measurements a definitive test, is there something else I could try or may have done wrong?

Also is there a way to parse any info from the A10KX2 I recognize the 10K OHM from my leftmost measurements, is the X2 basically saying two channels or something, does the A indicate anything? Perhaps audio?

Update

Turns out the modern equivalent part number for this component is the  VK369300 POTENTIOMETER A10K CLP/CVP. I soldered in the new part and now both left and right channels are operating properly so indeed the slide pot went bad.


texts: Capacitive Moisture Sensor - Is AC or DC better/more accurate?

texts:
I am looking into making a capacitive moisture sensor. This has been discussed many times already, but I am not sure what is the better option, AC or DC.

I want to run this off of a battery, so DC should be easier, but I read the following paper (tried to understand as best I could) and they used AC. From looking at it they did this so they could adjust the frequency and found that they had better readings for lower moisture levels at a specific frequency.

http://ourspace.uregina.ca/bitstream/handle/10294/5765/Knutson_Kevin_198302207_MASC_ESE_Fall2014.pdf?sequence=1

Does this make sense? Can anything like this be done with DC?

Or should I just follow this lead and try something like this myself?

I'm new to electronics so bare with me. Thank you in advance.


texts: What's the right way to draw these capacitors in a schematic?

texts: I placed my capacitors in this way (A) but another person tells me that a better way is like this (B) which one is the right one.


texts: I have been studying the concept of Time Division Multiplexing, but I have not been able to understand some stuffs, for instance, I have not been able to understand why the sampling rate for audio is 8Kbps and then they say the frame length is 128ms, I saw on another documents that the frame length would be 1/8000 which gives 128µs, I am really getting confused, as a matter of fact I am confused, on another documents I was also asked to Explain Time Division in terms of sources and their bit rates. I would like some help on all these please, maybe a little explanation of the concept would be also good, so that I can view it from another persons point of view, thanks...


texts: Live variable view using openOCD and VScode

texts:
I really like using VScode + cortex debug extension + openOCD  over Keil or Eclipse in embedded projects. Although i wasn't able to figure out how to set up live variable view, which you can set up with eclipse + openOCD.

1. Is it possible to see refreshing values of global variables over SWD using openOCD and cortex debug on VScode?

I can only see variable values when i pause the program, when the program is debugged i see:

When running:

counter: not available

When paused:

counter: 550

Cortex debug config:

{

    "version": "0.2.0",
    "configurations": [
        {
            "name": "Cortex Debug",
            "cwd": "${workspaceRoot}",
            "executable": "D:\\Code\\embedded\\STM32F1\\build\\STM32F1.elf",
            "device": "STM32F103C8",
            "request": "launch",
            "type": "cortex-debug",

            "servertype": "openocd",
            "svdFile": "D:\\Code\\embedded\\STM32F1\\STM32F103.svd",
            "configFiles": [
                "D:\\apps\\openOCD\\OpenOCD-20190426-0.10.0\\share\\openocd\\scripts\\board\\stm32f103c8_blue_pill.cfg"

            ]
        }
    ]
}
```


texts: Multiple devices on a CAN bus via the OBDII diagnostic connector in car

texts:
We have an aftermarket cruise control installed (in Suzuki Swift), which is connected to the OBD-II connector to access the CAN bus (according to the installation manual, it uses just CAN-L and CAN-H pins from the connector).

Now I have bought an OBD-II Bluetooth module. Could it be used at the same time as the cruise control?

If I understand the Wikipedia page on CAN bus properly, devices are connected to the bus parallel and terminator resistors are only at the two ends of the bus line. So it should be possible to have both devices connected to the OBDII connector... About using the devices at the same time, I think that would depend on which ID the cruise control is assigned to (so that it would always get priority above the Bluetooth module).

To summarize the questions:

1) Is it possible (and safe) to have both these devices connected to the OBD-II connector at the same time?

2) Is it possible to use them at the same time? Is it common for the diagnostic devices (like the ELM327) to have the lowest ID on the CAN bus to not interfere with other devices on the bus?


texts: Several basic questions about alternating voltage / current

texts:
I have a few straightforward questions about AC but surprisingly can't find any of explicit confirmations.

I understand that in reality all this is much more complicated but assume example below is greatly simplified case, only steady state with no any transient phenomena, TV acts like perfectly matched load without any reflections etc. For now I'm interested if my basic understanding is correct or not.

Here is static illustration of alternating voltage / current. And this is image from Wikipedia article about transmission line, which looks pretty similar.

Is it animated version of AC which demonstrate propagation of alternating voltage (and current) waves from AC generator (assume it connected on left side) toward load?

Now, I plug, say, TV set power cord into electrical wall outlet. There would be exactly same picture: constantly changing electric field due charges, magnetic field (due currents) and the waves would appear between/around "live" and "neutral" conductors in the outlet as well as wires inside the cord. Is this correct?
Since electric field constantly changing as I noted above, potential difference associated with the field constantly changing as well. Hence, actually, "live" and "neutral" wires (and wires inside power cord) keep permanently recharging to corresponding PD as waves propagates between them, with peaks +311V and -311V but for convenience there is famous ~220-240V RMS.
Am I right?
At same time "neutral" wire can be grounded for safety reason, so PD between "neutral" and the Earth is ~0V?
At last I'm wonder what if we don't plug anything into outlet, will it act as open-ended transmission line?

Sorry for my english and thanks for the help.


texts: Impedance matching routes in Eagle board

texts:
I am making my second board using Eagle CAD. I have different components with a set of different sizes. I set the minimum width for lines to be x. That way, the autorouter creates EVERY line in that width. The problem is that other components are wider, so I think I'd need to somehow widen the lines on the connections to that component (or probably not, the highest frequency in my circuit is of 16 MHz).

How may I do that?


texts:
I have an Altera DE2-115 with an RS232 port. I also have a USB-to-RS232 cable with the connector like this. One is male and the other is female, so they should fit just fine. However, I cannot get them to connect physically due to the protruding screws by the sides.

I can physically unscrew the metal bits on the Altera board, and these connectors would then connect just fine. However, is this a good idea? Will it damage the board somehow?


texts: How are the resistor values R1 and R2 calculated for a transistor amplifier that has a voltage divider bias

texts:
Good day friends

I am trying to analyse the working of transistor amplifiers with a prime goal of designing a good audio amplifier that does not produce much distortion in the output. I am restricting my analysis to the follow two general purpose transistors:

BC107
2N3904

I started my analysis from the very basics. To calculate the value of resistors for the emitter and collector, I simply used the Kirchoff's voltage law for the output side and got the values as 1.2k and 2.2k respectively. Coming to the input side, I had a little bit of difficulty to properly deduce the necessary values. However I had studied once that the Base voltage should always lie in between that of the emitter and the collector. So I randomly chose the values as 22k and 68k for R1 and R2. However probability for a random guess to work is always less.

I constructed the circuit in Multisim to simulate the output. Here is the circuit:

This circuit is highly inefficient and it attenuates the input signal rather than amplifying it. Here is the output from the oscilloscope:

The pulse like signal is the output that I got from the amplifier. Similar results were obtained when I used BC107 transistor. This result is very frustrating.

What I require is some guidance on properly calculating the resistor values in order to properly bias the transistor to the active region. Can anyone please provide a good systematic procedure with explanation on calculating the resistor values for this purpose?

Edit: I have changed the peak voltage to 2V. I am getting an amplification but the wave is pulse like. Also I constructed this circuit practically on a breadboard. The audio output intensity is much less than what I hear when I connect the audio source directly to speaker. What should I do? Also please provide a procedure to calculate the biasing resistor values.


texts:
I'm trying to make a circuit that has a load resistance of 2 Ohms, load current draw of 2A and voltage of 5V.

The circuit can only be fed with a 5V@500mAh battery.

Here is a diagram I have thought of:

Please excuse me for any technical errors since I'm new to the field.

I would love to get some suggestions regarding whether this circuit is correct.

Thank you.


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