texts: Need help with designing IR sensor, current to voltage converter

texts:
I would like to measure accurately (as possible as) using an IR LED and an IR phototransistor. I am using the following parts

SFH4550 - IR LED

BPV11 - IR Phototransistor

Obviously, the transistor gives a current output proportional to light. That current has to be converted to a proportional voltage.
What are the pros and cons of active vs passive current to voltage converters?

Passive:
Something like this where the transistor is the detector which is a current source:

versus
Active:
Something like this where current i is from the phototransistor:

Also how can I improve each method to give the best signal...reduce noise, flicker, etc?

Thanks, any help is appreciated!


texts:
While opening what is labelled as a "Badge Isolator" from a dishwasher, a Ferrite core broke.

The core goes through the PCB, and is comprised of a U part and an I part.

I am going to assume that the I was glued on the U, after mounting them on the PCB.

So the I part came off, and the U part broke in two pieces.
I thought I would just super-glue everything together and be done.

However, the dishwasher no longer works.

Is a Ferrite Core that susceptible to cracks?
How did the manufacturer close the core loop? Using a special purpose glue? Or would any glue work?


texts:
I am using two MOSFETs (IXFB210N30P3) at about 100kHz (with different duty cycles) to split current from a 100V rectifier into three separate coils. This is a very rough schematic of (one branch of) the circuit, where the PWM controller is putting 15V across the gate at 100kHz. This is a corrected repost of an earlier thread yesterday. I apologize for taking pictures of the scope, but I don't have a USB on me.

simulate this circuit – Schematic created using CircuitLab

Even at small voltages (~1-2V) from the DC source (V1), I am seeing odd voltage spikes at the drain of the MOSFET, of two different varieties. Without the capacitor/resistor snubber circuit (R2/C1), voltage builds at the drain to several times the applied voltage, and at even higher voltages, it spikes erratically and interferes with the gate voltage.

NOTE: cyan is gate, yellow is drain, purple is at the positive terminal of V1.

V1 at 1.1V: V1 at 1.5V:

However, with the capacitor and resistor snubber switch, up to a small voltage (around 1.2V), the voltage at the drain is flat but still nearly twice the applied voltage (around 2.2V), possibly because it is charging the capacitor, but this too breaks down if a larger voltage is applied. I've tried calculating the solution analytically, but none of the analytic solutions predict the amplified voltage. My solution in Mathematica would suggest a peak voltage of only 40 mV.

Here is a video of the voltage behavior (without the resistor/capacitor snubber) as the V1 voltage is increased. I have no idea what to attribute this to, and my various ferrite beads, diodes, and RC filters/snubber circuits haven't been able to stop it. I'd appreciate any advice/comments on how to fix this! Thanks.


texts: AD8221 for high side small current measurement

texts:
I'm trying to design a power supply for an academic project, which can supply +/-10V and can also measure the output current, hopefully down to nA range for a maximum of 5mA.

To perform the current measurement, I'm using various high side resistors(in the schematic there is just one resistor for the sake of simplicity. I think I'll switch the resistors with a relay) to sense the output current(R2), using a AD8221 Precision Instrumentation Amplifier.

As you can see the output voltage is following the input voltage, with a little overshoot, which is fine i think. Watching at the current measuring plot however, there's something wrong.
The output current is +/-5nA, which is what i expected, but in the output voltage node "MEASURE" plot there's something strange.

I'm using a 10kOhm current sense resistor and the instrumentation amplifier's gain set to 100, so, with a +/-5nA output current, the output voltage should be: 10kOhm*(+/-)5nA*100=(+/-)5mV. Instead, as you can see, there is this strange waveform which is everything but what i expected.

Do you have any suggestion to solve this issue or even improve the circuit?


texts:
Why is that there are two different Beta constants for a same thermistor even though Beta constant depends on the material?

For example: Murata's NCU15XH103D60RC has three different beta constants:

at B25/80: 3428,
at B25/85: 3434,
and at B25/100: 3455


texts: help me make a bi-directional motor circuit?

texts:
the first circuit is supposed to make the motor moves clockwise and anti clock wise according to the potentiometer.
the figure's components are
IC1: 741 op-amp
Q1: TIP3055 NPN
Q2: MJE34 PNP (yea it's written PNP but it's NPN in proteus 8)

it didn't worked so it has been redesigned as shown in the second figure
IC1: 741 op-amp
Q1: TIP3055 NPN
Q2: MJE350 PNP

the different result was that the motor is now moving anticlockwise. any edits to make it move in the two directions ?


texts: Difference between High- and Low- side switching of power?

texts:
Is there any real difference between high- and low-side switching?

Assume:

Switching is for on/off control of an object (My case RPi)
Base/Gate can be driven to Vcc and GND


texts: what is the application of "one time programmable" bytes in my flash memory?

texts:
My flash memory device A25L032 has 64 one time programmable bytes. It also has software and hardware protection modes for blocks, sectors as well as the whole chip.

What application do one time programmable bits have since flash is nonvolatile anyway and we also have protection modes for blocks and sectors.


texts:
I am a software developer (using high level languages like .NET,C,C++ etc) trying to understand how computers work at a lower level.

I have asked questions like the following in the past and got some useful responses: Map processor to circuit diagram.  I have bought an Adruino board to help me.

What other hardware do low level gurus buy to learn more about hardware and lower level programming? Would a Raspberry Pi be helpful (I believe they are targeted at children).  Also I was thinking about buying a tablet.


texts: Electret Mic signal amplification without DC offset

texts: I'm working on a small audio project and I need a circuit that does the following: take a signal from an electret mic, rectify the signal, amplify it, and remove the DC offset. I have tried many circuit designs but they are not working fine with me (too much noise and with DC offset). Should I mention that the electret mic's resistant is approximately 2.8 kΩ. Thanks in advance. any help will be appreciated :)


texts:
I'm rather stuck trying to compute the inverse Z-transform y[n] of the function below. I'm having trouble selecting the correct formulas from the table to achieve the right solution.

Any help with the solution will be greatly appreciated.

\$ Y(z) = \dfrac{1}{{(1 - z^{-1}})^3} \$


texts: Choosing ADC with wide input voltage range (0-10V)

texts:
I faced with the task to measure several inputs (0-10V analog) with galvanic isolation.

Using plain Google search (like '0-10V adc') I found several solutions like Linear Technology LTC1854/55/56 which has 8 inputs (single ended or 4 differential), -10...+10V input range (reference and supply voltage generated by the IC) which is very convenient. Galvanic isolation can be easily achieved by digital interface decoupling.

However this IC has SPI digital interface. I'd prefer I2C.

So I go to selector tools at several sellers and manufactures but no one has an option to choose wide input range. I can choose resolution, sampling rate, analog and digital power supply voltage... Anything! But I see no opportunity to filter ADCs with wide voltage inputs.

Can anyone suggest how can I search needed device? Maybe this parameter can be referred as "wide input range" or anything else? Maybe there are any selector tools allowing me to
choose this option?

Thanks!


texts:
All of the digital communication protocols I know, are built on the principle of the minimum distance, error detection and error correction.

There are some protocol able to detect and or correct "shift errors" in the time acquisition, i.e. the error of acquiring twice the same bit because a mismatch of the clock rates?


texts: Fuse Protection inline with DC Brush Motor

texts:
I have run into a number of instances where my 12A DC brush motor (linear actuator) is being overloaded. I have tried fusing it with a 10A Blade Fuse as well as a 15A Blade Fuse. In both instances, the fuses failed to blow. I was under the impression that under-rating the fuse would cause it to blow sooner, and over-rating it would allow for a bit more amperage draw (or current spike) and blow.

Is there a reason why the fuses are not blowing in either situation?


texts: Can't observe DC offset in a simple RC circuit with an oscilloscope

texts: I have a circuit with a power source and wave generator connected to capacitor connected to resistor. With an oscilloscope probe attached between the capacitor and resistor, why is it that when applying a DC offset there is no visible offset on the oscilloscope?


texts:
I'm working on an inclass project, for a two-tone alarm circuit. The 3V source represents two AA batteries. We've implemented this successfully on a breadboard. The IC used for the Inverted Schmitt triggers is a 74HC14N.

I've been hinted that there is an issue regarding current spikes on D4, but I can only see a very short initial spike...is this a major issue?

We have also been told that if there is not some base resistance, such as the one in R5, this will cause major issues with the transistor. We have implemented it without this R5 and it works as expected.

Any other comments or ideas on things to explore would be really appreciated.

I've seen this implemented with far fewer components, but we got to this point using our knowledge.


texts: Distance reading with Garmin lidar lite v4 over I²C with Arduino Due fails when connecting stepper driver

texts:
I am using following configuration:

Arduino Due
Garmin Lidar-lite V4 distance reading by the Arduino over I²C
Several Stepper motor controlled by the same Arduino through drivers (DM320T and DM542T)

Here is the problem:
When the stepper drivers are disconnected (i.e. not powered), the distance readings work as expected over I2C, but as soon as I power the drivers, I can no longer perform distance measurements and it looks like the Lidar freezes.
It seems like there are interferences, but how to be sure? Where to start to solve this problem? Any suggestion on the steps to undertake?
The Arduino and the stepper drivers have separate power supplies, but grounds are put common.


texts: Why is there a 66 Vac reading on the metal shield of our AC socket?

texts:
Today, out of curiosity, I took a measurement between the water pipe (presumably to be ground) and an exposed area of the AC socket with metal shielding (supposedly to be ground as well), and got an AC reading of 66 Volts, and 0.21mA.

Why? I don't understand


texts: Is there a device/battery that can be charged while it's being used?

texts:
You'll have to excuse my sheer lack of knowledge, I'm sure this must be among the most basic of questions posted on here.

I have a dynamo (motor), which is powering an LED (for argument sake).

If the dynamo stops spinning, the LED's no longer powered.

Is it possible to power the LED with batteries that are currently being charged? So, if the dynamo stops the LED has a bit of power left in the batteries to carry on using until the dynamo starts spinning again?

Worth noting, these are all very small, low-powered devices I'm talking about. Nothing of scale.

Thanks very much


texts: Problem with GDS export of a layout in Agilent Advanced System Design (ADS)

texts:
I have a problem exporting my layout design in ADS. It gives me an error that the layer map file not found in the library and it creates an empty file.

I'd appreciate if you could let me know what this layer map is and how it is created.

Thank you,


texts: Quick question about signed full adders (carry and overflow)

texts: For a 4-bit signed full adder, the output range in decimal is -8 to +7. I created a 4-bit signed full adder in verilog and simulated it. When I added +5 and +3, I got a sum of -8 and overflow=1. This should be correct right? When I added +3 and -1, I got a sum of +2 and a carry of 1. Is this correct or is my code wrong?


texts: So can we just draw 500 mA from any USB port without enumeration now?

texts:
The USB Type-C Spec R2.0 defines the USB Type-C Current feature, in which the power Sink observes the voltage on the CC pin to determine how much current is available from the Source, which falls into one of three categories:

0.25 to 0.61 V: Default
0.70 to 1.16 V: 1.5 A
1.31 to 2.04 V: 3.0 A

When a Source is advertising USB Type-C Default current, the Sink behavior is defined as
follows:

It connects as a USB 2.0 or USB 3.2 device, after which the Sink shall follow the appropriate USB specification.

So far it sounds like the standard USB negotiation process, where you enumerate with 100 mA or less, and then request 500 mA in your descriptors and possibly get rejected by the Host.
But then it gives another option:

It attaches as a USB Type-C Power Sinking Device (PSD), after which the Sink may draw up to 500 mA.

A Power Sinking Device (PSD) is defined as:

Sink which draws power but has no other USB or Alternate Mode communication function, e.g. a USB-powered light.

And that's all it says in the spec; I can't find anything else about PSDs.
So it sounds like a circuit with no communication ability is legally allowed to draw 500 mA from a USB Type-C connector that advertises any of the 3 current ranges.
But then in Legacy Cable Assemblies, the USB Type-C to USB 2.0 Standard-A Cable Assembly is described as:

Pin A5 (CC) of the USB Type-C plug shall be connected to VBUS through a resistor Rp (56 kΩ ± 5%).

Which puts it into the "Default" category above.
So this would mean that a device can legally draw 500 mA from a standard USB-A port through a C-to-A cable without any enumeration or communication at all?
PSDs were added to the spec in Release 1.3, July 13, 2017, described in Default Current Clarification for non-USB Devices which gives a little more context:

Brief description of the functional changes proposed: Clarify the power a non-USB device is allowed to draw when a Source advertises default USB Type-C current.
Benefits as a result of the proposed changes: Allows a non-USB device such as a power bank to draw up to 500mA when the Source advertises default USB Type-C Current.
An assessment of the impact to the existing revision and systems that currently conform to
the USB specification: Likely little as the Sources are already required to be able to supply at least 500mA when advertising default USB Type-C Current.

Even legacy USB-A Sources?


texts:
Not sure if this is the place where this belongs but...

I'm working on adding a second extruder head to the rep rap i have that uses RAMPS Electronics.
http://reprap.org/wiki/RAMPS

I'm trying to assign a bit to the arduino mega that regulates with extruder were using. 1 for tool 1 and 0 for tool 2. any one know how I could do this or is anyone able to at least point me to someone who might?


texts: ECG electric design: 1 and 3 op-amp designs from a safety point of view

texts:
During the design of an ECG using an instrumentation and a differential amplifier, we can across this question:

Comparing the one and three op-amp designs from a safety point of view:  of the two designs, which provides a current path from the electrodes to the ground (and therefore are potentially dangerous)?

I know that is something related that in bioelectronics, current is dangerous.  Especially, because nerves are current sources due to an exchange of ions, so allowing current to flow to ground could be dangerous without protection.

However, I am not sure how this is related 1 and 3 op-amp designs. Some of this topic was discussed in the following link (but nothing regarding safety):
https://electronics.stackexchange.com/questions/91499/three-opamp-instrumentation-amplifier-vs-single-opamp-implementation#=


texts: STM32 + ESP8266 Websocket Client get HTTP/1.1 400 Bad Request from server

texts:
I'm working on a small IoT project on STM32F070 Micro controller interfaced with ESP8266 Wifi module.
I have developed a Websocket client application on STM32F070 controller which will communicate to remote Websocket Server and will Exchange data over connection.
I make TCP connection with Server from Websocket Client but after sending Websocket request Headers, I'm receiving HTTP/1.1 400 Bad Request from server and connection gets CLOSED.
Here are logs from ESP8266 UART line:
    ready
WIFI CONNECTED
WIFI GOT IP
AT

OK
ATE0

OK

OK
WIFI DISCONNECT
WIFI CONNECTED
WIFI GOT IP

OK
+CIFSR:STAIP,"192.168.43.194"
+CIFSR:STAMAC,"48:3f:da:66:cf:2c"

OK

OK

ERROR
CLOSED

ERROR
CLOSED
CONNECT

OK

OK
>
Recv 227 bytes

SEND OK

+IPD,103:HTTP/1.1 400 Bad Request
Connection: close
Content-Type: text/html
Content-Length: 11

Bad RequestCLOSED

Here are the headers I'm sending to Remote Websocket server
AT+RST
AT
ATE0
AT+CWMODE=1
AT+CWJAP="Txxxxx","08080808"
AT+CIFSR
AT+CIPMUX=0
AT+CIPSTART="TCP","192.168.43.69",8080
AT+CIPSEND=227
GET / HTTP/1.1
Host: 192.168.43.69:8080
Connection: Upgrade
Upgrade: websocket
Sec-WebSocket-Version: 13
Sec-WebSocket-Key: NhEEf0jUzTLT3ZC2jSW1PnsX
Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits

Here is WebSocket Server Code in Node Js.
var bodyParser = require("body-parser");
const express = require('express'); //express framework to have a higher level of methods
const app = express(); //assign app variable the express class/method
var http = require('http');
var path = require("path");
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
const server = http.createServer(app);//create a server

//***************this snippet gets the local ip of the node.js server. copy this ip to the client side code and add ':3000' *****
//****************exmpl. 192.168.56.1---> var sock =new WebSocket("ws://192.168.56.1:3000");*************************************
require('dns').lookup(require('os').hostname(), function (err, add, fam) {
  console.log('addr: '+add);
})

/**********************websocket setup**************************************************************************************/
//var expressWs = require('express-ws')(app,server);
const WebSocket = require('ws');
const s = new WebSocket.Server({ server });

s.on('connection', function(ws, req) {
  console.log(req.headers);
  console.log(req.params);
});

//when browser sends get request, send html file to browser
// viewed at http://localhost:30000
app.get('/', function(req, res) {
res.sendFile(path.join(__dirname + '/index.html'));
});

//*************************************************************************************************************************
//***************************ws chat server********************************************************************************

//app.ws('/echo', function(ws, req) {
s.on('connection',function(ws,req){

/******* when server receives messsage from client trigger function with argument message *****/
ws.on('message',function(message){
console.log("Received: "+message);
s.clients.forEach(function(client){ //broadcast incoming message to all clients (s.clients)
if(client!=ws && client.readyState ){ //except to the same client (ws) that sent this message
client.send("broadcast: " +message);
}
});
// ws.send("From Server only to sender: "+ message); //send to client where message is from
});
ws.on('close', function(){
console.log("lost one client");
});
//ws.send("new client connected");
console.log("new client connected");
});
server.listen(8080);

WebSocket is tested with Mobile WebsocketClient Tester Application. Its working fine. enter link description here


texts: Why do we ignore parasitic capacitance in dc analysis of transistors?

texts:
Consider a transistor that has parasitic capacitance of the order of pico-Farads.

  Then at low frequencies, consider 10Hz

  $$X_C=1/(2\pi f C)$$

  \$X_C\$ will be in the range of giga-ohms.

This means that the resistance of the device is so high, that it must not allow current to flow through it.

This says us that any device that has a parasitic capacitance must now allow dc through flow through it. But indeed devices with parasitic capacitances allow dc to flow through them. How is this true?

This also means that at dc, the reactance is infinity and no current must flow through the transistor, but indeed current flows the device and we do many dc analysis.

How does this become possible?


texts:
I use virtuoso cadence to make two bridge rectifier,one of them use NMOS to replace the diode,and the other use DION_MM directly,like the picture shown

But their simulation are wrong,like the picture below shown,and i want to ask where is my schematic wrong?the gnd position?The red line is the wave of right schematic,and the blue line is the left,and the black line is the alternating current voltage source


texts:
I'm using an MCP3425 ADC, it has differential inputs but I'm using it as single ended mode.
The signal that I want to digitize comes from an integrator circuit (an op amp with a capacitor in its feedback loop).The signal is basically a ramp that lasts 2 seconds and goes from 0V to up to 3.3V.
Given that this ADC can not measure signals of voltages greater than its reference of 2.048V. And I want to use the full range of my signal, is it OK if I improve it's range by driving the non-inverting input with an 1.25V voltage reference and the inverting input with my signal?
Because 1.25V + 2.048V = 3.298V, when the ramps is 3.3V the diferential voltage will be of 2,048V.
I have already tried this circuit and I know It works, what I want to know is if this approach does not hinder circuit performance in any other aspect. (e.g.: bandwidth, noise, EMI, etc)
Below is a simplified schematic of my circuit.

simulate this circuit – Schematic created using CircuitLab
EDIT: I forgot to add that I want to improve range without sacrificing resolution, that is why the is no atenuation stage between integrator and ADC.


texts: Could transporting electricity using plastic water pipes be feasible?

texts:
Normally a household is connected with 3 different connections:

Waterpipes
Electric cables
Internet fiber

Water conducts electricity (and can also transport light), why aren't we transporting electricity using plastic water pipes instead of using copper cables?

If you somehow could use water for optical internet, that'd be a 3-in-1 solution.


texts:
I was talking to a colleague about the limitations of USB cable length and as far as I could remember it was limited by the tight window the host requires the device to respond in (mentioned here).

He pointed out that Ethernet is transferring data at a higher rate (USB 1.5/12/480/5,000 Mbit/s (depending on mode) vs Ethernet's 10/100Gbps) and allows for a longer cable length (100m for CAT6 cable).

So I guess we're both wondering what aspect of the USB protocol limits the cable length to 5m and how does that differ from Ethernet?


texts: Cloning a 433Mhz Transmitter using RWS-375 Receiver

texts:
I've bought that famous Receiver/Transmitter RWS-375 and TWS 375. I want to clone the remote control of my  garage door.
So I connected the RWS-375 in my Arduino, and build a program to receive the sinal that the remote control send.

However every time I press the button the program writes differente sequence of characters. I mean, I never get the same sequence of characters from the remote control.

I've already tried changing the bits per seconds rate, but I think the correct is 9600, right?
Also is there anything else I should verify in that I'm missing?

Note that I've already check that they operate at the same frequency...

Thanks guys


texts: Control Engineering: Why are the Equation Error and Output Error different?

texts:
When modelling a system you must first estimate the form of the transfer function (order, time delay etc.), and then estimate the parameters (coefficients for the transfer function).

A common way to estimate these parameters is to formulate a cost function describing the accuracy of the estimates, and then minimise this cost function with some numerical or analytical optimisation method. Two common forms of the cost function are the Equation Error and the Output Error. These are shown for a discrete time system below:

Output Error: e(k)

u(k) and y(k) are the actual measured system input and output and y(k)hat is the model output:

$$e(k) = y(k) - \hat{y(k)}$$

$$e(k) = y(k) - \frac{\hat{b_1}z^{-1}}{1+\hat{a_1}z^{-1}}u(k)$$

And the cost function is:

$$J = \sum_{k=1}^{N}e(k)^2$$

This can be solved numerically, e.g with gradient decent or the genetic algorithm.

Equation Error: E(k)

$$E(k) = y(k) - \hat{y(k)}$$

$$E(k) = y(k) +\hat{a_1}y(k-1)-\hat{b_1}u(k-1)$$

$$J = \sum_{k=1}^{N}E(k)^2$$

This can be solved analytically by differentiating J with respect to each parameter and equating the result to zero, and then solving the resulting set of equations.

It is said that the Output Error is better for noisy data but the equation error is better otherwise since it does not suffer the local minima problem.

My Question:

It seems that by using the Output Error or Equation error the cost function has different properties, but to me they seem to be fundamentally using the exact same formula, but just re-arranged to look different. So why does the cost function end up with different properties? I.e one is solvable and one is more robust to noise.

This is what I mean by saying they use the exact same formula:

The equation error is defined as the actual measured output minus the model output:

$$E(k) = y(k) - (-\hat{a_1}y(k-1)+\hat{b_1}u(k-1))$$

Where the model output is:

$$\hat{y(k)} = -\hat{a_1}y(k-1)+\hat{b_1}u(k-1)$$

But if you re-arrange this formula so it is in transfer function form:

$$\hat{y(k)} = -\hat{a_1}y(k)z^{-1}+\hat{b}z^{-1}u(k)$$

$$\hat{y(k)}(1+\hat{a_1}z^{-1}) = \hat{b}z^{-1}u(k)$$

$$\hat{y(k)}=\frac{\hat{b}z^{-1}u(k)}{(1+\hat{a_1}z^{-1})}$$

Which is exactly the same as the Output Error. So the Output Error formula and the Equation Error formula are the same equation but just re-arranged to look different.

So why is the cost function for one solvable and for the other it is not?

And why does the result of optimisation result in a more noise-robust model when using the cost function with one and not the other?

Sorry if this is posted on the wrong site. There is no stack exchange site for control engineering, so I figured this is the next best place.


texts:
I am doing a small project with ESP32 and HX711 and I need to have 3 load cells.

Like this one:

I am totally newbie in electronics, my ground is programming.

What I found are projects with 1, 2 or 4 load cells connected together.

I need to have 3 load cells , it is to be used as scale for a cylinder.

Is it possible to be done with HX711? How?

EDIT
Best I could find:
Load Cell

HX711 Datasheet


texts:
I have designed the following optoisolator for SWD interfacing with an STM32 device and J-LINK programmer:

This is the generic schematic:

And this is a single optoisolator schematic:

I am not able to interface with the board in the J-Link commander. I see that J-Links attempts to reset the device but fails to communicate. Is there any basic flaw in my design?
Can the bidirectional SWDIO line be the case? I would appreciate all help.


texts:
I bought a switching power dupply (SMPS) rated at 5V | 20A | 100W.

But it seems I don't understand how power supply works. I need total of 18A on output, but that seems to be over the limit of standard 16A | 220V wall outlet's limit.

How would I power this supply without burning my house down? I bought fuses and relays but that can only handle max at 10A.

Reason for such high amperage needed:

I was going to power 300 LEDs that require 5v 60mA per LED.
I'm planning to make it in 2 parallel structure, giving me 150 leds each side. It turns out I need 5v each side with 9A flowing each side, totaling 18A.
So does two 9A merge on outlet's side?


texts: Trouble with DC/DC (switching) converter

texts:
I have a DC/DC converter with +5V input and ±15V dual output to supply power to the analog portion of a board (just two operational amplifiers).

The +5V DC input comes from an external box that uses an AC/DC switching converter.  I have an AWG-16 cable connecting the +5V from that external box to the power-in connector of my board.

Problem I'm having:

The DC/DC converter fails to provide power if I connect the already-powered cable directly to the board's power-in connector.
The DC/DC converter does work properly and does provide power if I plug the cable and then provide AC power to the external box.
When it fails, I measure approx. +1.5V at the positive output, and approx. -1.5V at the negative output.

Schematic (relevant portion) is included at the bottom;  some details of the board are as follows:

The power input to the board is a "thick"(ish) 4-pin connector carrying two grounds, +3.3V, and +5V.
The +5V go to the input of the DC/DC.  It has decoupling (0.1uF X7R) and a bulk capacitor (47uF Aluminum Polymer) right next to the power-in connector.
The power-in connector is approx. 3cm away (in trace length) from the input pin of the DC/DC converter.
The DC/DC converter does not have its own decoupling capacitor next to its input pins.

This is the schematic (all 0.1uF capacitors are ceramic, 50V, X7R):

This is a (synthetic) view of the board (3D view produced by KiCAD), to give you an idea of the physical layout of things (the aluminum capacitor at the top, next to CP4, that one is CB5):

These are the attempts to fix the issue:

Tried adding a ferrite bead at the input of the DC/DC converter — had some Murata Electronics BLM21PG331SN1D hanging around, so I cut the trace, pealed a bit of the solder mask and soldered the ferrite bead between the bulk capacitor and the DC/DC converter's input pin.  No difference whatsoever.
Replaced the DC/DC converter with a pin-compatible model.  Instead of the CUI PDS1-S5-D15-M-TR, I installed an XP Power ISA0515 (on a separate board; that is, the ferrite bead is in one board with its original CUI converter, and I put the XP Power converter on another board, without a ferrite bead).  This actually made the problem far worse.  Now, I only get power once every 5 or 10 times that I plug the AC power (seemingly randomly).

Any feedback/critique on the schematic?  Any advice on typical strategy to make the circuit more reliable?  Alternatively, any advice on what to try next to figure out the cause of the issue?

[UPDATE]:
I added 3.6k resistors in parallel with CP1 and CM1 (directly loading +15V and ‒15V).  I confirm with an ohmmeter;  resistance between either +15V or -15V and GND is around 3k.  I did this on the board with the replaced DC/DC (i.e., with the XP Power converter).

Did not make any difference.

Regarding the oscilloscope captures.  Yesterday, I captured the 5V input in instances where the ±15V came up and also instances where it didn't. The traces for both cases are essentially identical.  Something like this:

Now, this morning, with one of the original/unaltered boards (with the CUI converter, no added load, no added inductor), the +15V rampup shows this weird behavior:  (horizontal scale is 10 ms/div)

However, this one does come up reliably (as long as I power-up the external power supply that delivers the +5V, as opposed to plugging the cable carrying the +5V to my board).

Any ideas?

[END UPDATE]

[UPDATE 2 — presumably "problem solved"]
Strange that with the XP Power model, the added load did not make a difference (and the datasheet also specifies a minimum load of 10%, which would be 3.3mA).

With the original part (the CUI converter), without any alterations (i.e., no added inductor), adding the 3.6k resistors now makes it reliably come up, regardless of whether I power up the "upstream" +5V supply, or whether I unplug and plug the already-powered cable to my board's input connector.
[END UPDATE 2]


texts: I'm trying to figure out the boolean expressions I need for drawing a circuit based on a state transition table. I wound up with the k maps below, but I'm not really sure what to do with them. Would I circle 3 or even just 2 x's and the 1 in the left table to make a more general expression for the first table? What do I do with the right side table with it not having any 1's at all?


texts: Could I transfer data over an induction coupled wireless power system

texts:
I’m looking to create a battery powered sealed sensor device. Battery recharge would be via inductive coils.
Is it possible to use the wireless power transfer as a data transfer link simultaneously?


texts: Circuit with Base of Transistor connected to ground

texts:
I am having troubles understanding a circuit where to base of a transistor is connected to the ground.

As far as I know a transistor needs a certain voltage on the base so electricity can flow from the collector to the emitter. However, if the base is connected to the ground this can never happen.

In the image you can see, that the base of T2 is connected to the ground and as Ue = 0, the base of T1 is connected to the ground as well. U+ = 5V (don't know if this is important).

Should an explanation be too much work, please point me in the right direction or post links to further resources that might help me.

Thank you very much in advance!


texts: what is the importance of input and output impedance of a RL low pass filter?

texts:
I read from the book that for a good voltage coupling, the input impedance must be larger than the output impedance of the previous stage, which requires a min value of Zin since the frequency of the input signal is not known. Also the output impedance must be smaller than the input impedance of the next stage, which requires a max value  of the output impedance.

My question is what is voltage coupling? is it like for eliminating the DC component of the input voltage?
and also also the output impedance must be below a max value to insure good voltage coupling?


texts: Increasing the gain of a BJT amplifier without affecting dc bias

texts:
Reading through my textbook, I came across a basic common-emitter amplifier that drives a load. Please have a look at the circuit, and input/output waveforms shown in the image below.

How would one increase the gain without affecting the DC bias? From my point of view, the value of RE would determine this. Decreasing this resistance would increase the base current, thereby increasing the collector current. Am I correct in my reasoning? I would appreciate some guidance.


texts: Why do we multiply by the square root of 3 to get the phase to phase voltage from the phase to neutral voltage? What would be the multiplication factor for a 6-phase system, where the adjacent phases are separated by 60° instead of 120°?


texts: Difference between horn and power resistor?

texts:
I have a circuit where my microcontroller is turning off and on a heavy load using a power MOSFET (I've also tried it with a MOSFET and a relay which yielded the same results). When I use a power resistor at 1.5 ohms everything works as expected. However, when I replace the power resistor with a car horn (measured at around 1.5 ohms using my multimeter), then when the circuit triggers the horn, I hear a horn sound for about a quarter of a second and then it stops, like the horn is somehow resetting my microcontroller.
Does anyone have any idea why a horn might act differently than a regular resistor?

simulate this circuit – Schematic created using CircuitLab


texts: Is shorting and removing independent sources related to superposition theorem?

texts:
I was looking at a derivation of differential gain for a BJT differential amplifier.

Along the derivation the power supply and the tail current sources are nulled. I mean the Vcc is shorted to ground and the tail current source removed.

What allows one to do that? Is it related to system being LTI or superposition?


texts: Can I connect two 6V 25W bulbs in series to a 12V supply?

texts:
I've two GE 4510 6.4V 25W tractor bulbs with me. Unfortunately, the only power supply I've in my possession is capable of outputting only 12.02V. Can I connect the two lamps in series to the 12V supply? I'm slightly confused because most of the posts on internet that mention about bulbs in series connection have same or higher voltage than the power supply.
Thanks everyone. Cheers!!


texts:
Could someone explain to me how reverse current protection in the STUSB4500 reference design should work?
The purpose of the secondary MOSFET was already answered in this question, but I took a look into the datasheet, and it is written there, that VBUS_EN_SNK can be either 0 or High-Z..?


texts:
I decided to test some diodes that I have, using a multimeter to measure their forward bias voltage. I set my multimeter to voltage test and connected the diode across:

I tested a bunch of different diodes, both germanium and silicone type, so I expected to see voltages around 0.2 - 0.7V. However, all diodes showed 0V!

I tried reversing the polarity of the diodes, as well switching multimeters. Always my measurement came out as 0V. So am I making some kind of mistake in measuring diodes, or are both of my multimeters/all diodes broken?


texts: Need Help Trouble Shooting A HP 8559A Spectrum Analyzer

texts:
I recently acquired an HP 8559A spectrum analyzer however instead of the HP182T display it was supposed to have it shipped with an HP180C display. I am unable to get the display to output a signal (I only get a dot / vertical line). I believe this is because the 180C is not compatible with the analyzer. If anyone how is more knowledgable with this I would appreciate any help.

(

Please note the display shows an almost identical image if the calibrator is connected.

EDIT: After some additional research and testing it appears that the display is not sweeping (if I sweep manually I get what seems to be the correct signal).


texts: How does JFET cascode amplifier reduce input capacitance?

texts:
I read that a JFET cascode amplifier has a reduced input capacitance thus lowering the Miller capacitance and will obtain wider bandwidth.

In order to obtain lower Miller cap, the  voltage gain must be lower to reduce the multiplication of stray input capacitance. BUT, how does this circuit reduce the input capacitance?

I only notice that the signal is directly-coupled to the lower JFET while the upper JEFT has its gate in AC ground. But I cannot understand how was that suppose to lower voltage gain (Miller capacitance)


texts: What is the greatest depth where we can communicate with the submarine over the sonar system in ocean? Also, how can we calculate how much data can be transmitted using this method?


texts: Why are the same alloys solid in solder wire and liquid in solder paste?

texts:
Is there a chemical difference between alloys in solder wire and alloys solder paste that make solder wires solid and solder paste fluids?

For instance, this solder wire and this solder paste both have the composition Sn96.5Ag3Cu0.5, but the wire is solid and the paste is fluid. I know that the solder wire has a core of flux inside, but apart from that I don't understand how at the same temperature one alloy is solid in the wire and fluid in the paste.


texts:
I am a scientist, and I have found myself needing to interface two disparate pieces of equipment.

I have a precise, automatically controlled current source that I wish to interface to a very expensive piece of equipment. The current source and its controller are designed under certain assumptions, namely that the 14 channels of its outputs have the same limit. My device, naturally, has different limits. I can't alter the logic of the source -- it's a black box. Of these 14 channels, 4 have a ±1A DC limit at ~60V, and 10 have 0.75A a

I want some sort of accurate fuse that I can use on the different channels: initially I thought of just "coping out" and using PPTC polyfuses -- our load is mostly inductive

simulate this circuit – Schematic created using CircuitLab

However, try as I might I can't find a PPTC polyfuse with a hold current of anything greater than half the trip current. This would cut the functionality of our device a lot, and the typical 500 mA hold current / 1 A trip current curve of a polyfuse would be far from ideal as we'd be operating quite a lot of time in the undefined behaviour in between. I really want it to go at something like 1A ±50 mA, not +0/-500 mA!

Is there a standard "better way" of doing this? I could go overkill and find a sensitive current monitor, ideally one with an analogue output going to a comparator, tripping a solid state relay if necessary.

Edit: The device generates magnetic fields in a spherical harmonic basis. There might be some induced "noise" on any of the lines, which would be caused by parasitic induction from a ~75A arbitrary waveform going through loops of copper nearby (in either direction) on a typically ms timescale.

The idea is to protect the device against getting physically burnt out either via a fault or through inappropriate driving. The expected use case is almost DC current drive: there's a 16 bit DAC driving the output and typically it's changed by ~mA on a ~1 s timescale and then left DC for minutes or hours. I'd like overcurrent protection on the scale of ms to 1 s rather than 10s of seconds.


texts: Connecting an arduino to desktop speakers

texts: I would like to get audio output through a pair of small desktop speakers (standard computer speakers - Logitech or similar). Is it safe to directly connect the ground bit of the 3.5 mm jack to the arduino ground (and same for some digital output)? Would any speakers just work (with/without their own amp)? I don't want either arduino or speakers to break.


texts: Is it a good idea to landfill using alternating power rails?

texts:
That is, for example, filling the top layer of a 2-sided board with ground and the bottom with power rail.

Will this form a big decoupling cap across the board, or will it give me horrible crosstalk?


texts:
I designed a PCB accoridng to the schematic above and here is the PCB:

It's not working as it' supposed to be.
After LM2937ET-10 (package SOT-223), I'm supposed to get +10 between pin 3 and pin 2 of this chip.
But when I put my 12v on input, I only measure 3V as output instead of 10. Is there something wrong?


texts:
Can we use n-channel mosfet in the place of p-channel? In my configuration I'm using 12v 40watt solar panel for 12v 7.5 Ah lead acid battery charging. in this configuration it should be p-channel mosfet for switching which gives positive voltage to battery for charging. Here I have common ground from input voltage and Battery, so I'm unbale to switch to n-channel mosfet. but p-channel mosfet are very difficult to get in the market.
so my question is can I use n-channel mosfet to pass positive voltage from source to drain? e.g. if I use STP80NF55


texts:
We have some pcb in which contains an MCU ,and some WiFi module .
Usually at start, the board takes 70-100mA with 3v3 .
It gets its current from the UNO board connected to a mac.
It works great like that .(if you wonder how the UNO can get this current,me too)

Problem starts when we try to measure current. If we take the fluke device, and put it in serial to the voltage of the pcb to measure current, what happens is that the MCU starts to get resets, and the WiFi module voltage is drops .nothing is works than.

We have tried to change the current scale on the Amper-Meter , from 20m to 20A.
Nothing helped.

*if we measure current of other stuff that consumes lest current, it DOES measure and show the right current.
The problem occurs only with the pcb that contains a WiFi module that takes 70-100mA.

connections are:
    3v3 from arduino - > Ampermeter plus->Ampermeter minus->board 3v3 .


texts: Is less than 1A enough for TP4056 module to charge one battery?

texts: I want to charge 3 separate 18650 cells with one charger. Each one of the batteries has their own TP4056 module. So in total there are 3 TP4056's. I know that TP4056 is rated at 1 amp input, though my USB charger only puts out 2 amps. I want to use USB male to 3 Micro USB splitter, to charge each battery equally, and by doing calculation: 2/3=0.666, each battery only gets 0.666 amps. So is 0.666A enough for TP4056 to charge a 18650 battery?


texts:
I'm trying to understand the attached schematic, which I came across when repairing an oscilloscope.

Am I right in thinking that this circuit is regulating VCC (5V) down to 3.3 and 2.5 volts? Why does the opamp use 12v rails rather than 5volts?

The non-inverting input to the opamp seems to be a voltage divider. I take this divider is used to provide a simple voltage reference?

Given that this is in an oscilloscope (a LeCroy LT342) is there any reason to use an opamp here rather than a voltage regulator?

One further thing that confuses me, is that on the board Q9 is not fitted, and has been replaced with a short between 2 of the pins. I can't understand how the circuit can work in this scenario, can anyone cast any light on this?

From my naive understanding, this seems like a bad design, and that it would be preferable to use a voltage regulator. What designed decisions might I have missed here?


texts: How does the feedback of this op amp works? [voltammetry]

texts:
I am trying to build an Arduino version of the voltammetry thing described in this paper. Before questions here is a little background for those who don't know what voltammetry is.

This device works with three electrodes, working electrode (WE), counter electrode (CE), reference electrode (RE), immersed in a solution (containing the sample and electrolytes). A potential (fixed, linearly increasing or cyclic) is applied between CE and WE, and if high enough, redox processes happen on these electrodes and some current flows between them. The reference electrode is there to provide a fixed V reference. The device must measure the current flowing from CE to WE and the voltage between RE an WE in order to build a voltammogram (x=V, y=I).

Here a simplified version of the schematics:

simulate this circuit – Schematic created using CircuitLab

The original project use an Atmel XMEGA. Vref is internal 1V. Op amp single supply is 5V.

How does that feedback work? Hint: when DAC put out, for example, 2V referred to ground, the opamp must put out 2V between CE and RE. No current must flow through RE.
Arduino does not have a DAC, can I build a low pass PWM filter on top of the first op amp or it is better to have two RC filters before it?

EDIT

Added original schematics

(Note: S1D is open during operation while S1A and S1C are closed, those switches are for dry tests)


texts: Inherent sample and hold in a comparator?

texts:
I have been reading up why a flash ADC does not (theoretically) need a sample and hold circuit. I have learned that this is because the comparators have an inherent sample and hold property, but I can not see why this is so. So please could you explain why a (op-amp) comparator has an inherent sample and hold property.

Some sources where this property is mentioned:

http://www.ijsrd.com/articles/IJSRDV2I3184.pdf
http://www.analog.com/static/imported-files/tutorials/MT-020.pdf


texts: Bidirectional level translator using N channel MOSFET

texts:
I'm using a n channel MOSFETa bidirectional level translator. The case when the body diode conducts the source end will be literally 0V or forward voltage of body diode, so the difference in voltage across gate to source will be enough to form a channel.

My question is: few seconds after the GPIO 1 pulls down, whether the channel between source to drain starts to conduct or not ?


texts:
I would like to find a datasheet for a part labelled "ZL5P", found on a small PCB inside a very cheap laser pointer.

(large solder blob on left is 3V input, blob on right is GND, laser
diode is black plastic package on extreme left).

The part measures as a standard "SOT23-6" package and I believe it is a voltage boosting IC of some sort.  It is accompanied by an inductor (adjacent) and a couple of SMD caps (on the other side of the PCB).

The circuit power input is a pair of AAA cells (e.g. 3v).  The output seems to be 5.4V going into one pin of a 3 pin laser diode (405nm purple laser diode).

The circuit draws 0.17 Amps from the cells.

I found one hit on alibaba for this part (37 cents each) but it made no mention of the full part number, nor the manufacturer.


texts: Setting a step-down regulator to provide constant drop on the following linear regulator

texts:
I would like to have a clean output from a linear regulator (variable 1-5V) but also a small heatsink on it, so I thought about placing a ready-to-use step-down module before it, and to wire it so that the voltage drop on the linear regulator is almost constant.

Since the step-down (buck) are non-isolated, in practice they also have three pins only.

My idea is to have a circuit like this:

simulate this circuit – Schematic created using CircuitLab

In other words, the potentiometer defines the final voltage at the output. The DC-DC regulator is set to have a constant 4V voltage on its output, that corresponds to the drop between input and output of the linear regulator.

Provided I use capacitors (ceramic and electrolytic) and ferrites between step-down and linear regulator, plus a ferrite also after the linear regulator, would it work? I have no other idea about how to set the same thing without using a double potentiometer.

Update

I wrongly used the ADJ pin of the step-down as if it were the ADJ pin of the linear regulator. It was wrong, because the step-down is a complete module, where I use the GND line. I updated the schematics.


texts:
What are the drawbacks of this design vs a design like the TI one here?

Should the feedback be on the other side of R2?

Are there any other gotchas using something like this, vs limiting using a 7v+- supply?

The purpose of this limiter is to prevent overdriving of a PCM1862 audio adc.


texts: Saturation Cascade MOSFETS (Need Help from EE Experts)

texts:
this is a very straightforward question.

I'm running a Harmonic simulation on ADS where I need to design a cascode amplifier of two NMOS and one PMOS, that have a gain higher than Av > -100. The catch is that all my MOSFETs need to be in saturation mode.

All I want to know if I did my calculations to keep them all in saturation mode correctly. I design everything but I need help specifically with that part. Here's the design.

The equations:

Don't worry about looking at anything else, just the Saturation equations. If I do them correctly, then the rest of the circuit will work.


texts:
I'm trying to control a 4 wire servo that was used in an RC car for the steering. It has two power connections, but I can't make sense of the other ones. If there is power on the red and black wires, the motor turns into one position and stays there, no matter what I put on the other wires. I also tried to vary the voltage of the power, no difference. How can I control its position?

The motor: https://drive.google.com/file/d/0B8Ox1li7YRxoa3ZBY2RNakxCT0k/view?usp=sharing

The board it was connected to: https://drive.google.com/file/d/0B8Ox1li7YRxoREt1Z3RNcXp4OU0/view?usp=sharing


texts: Why do we need to remove flux from circuit boards?

texts: My manager at work told me that the liquid flux we use when reworking SMD circuit boards is electrically conductive,and that is why he INSISTS that we clean every board we work on.Is he right,or is he pulling my leg?


texts: I have recently purchases an 120 Vac to 12 Vac transformer similar in design to the one shown here. I am curious as to the best way to wire this up. I am not a big fan of making a suicide cable for the obvious reasons of electrocution. If I pick up a set of these, would it be safe to splice and solder a 120Vac power cable into the connector?


texts: Can unconnected inputs make an IC get warm?

texts:
I am using an ATF16V8 PLD for some simple glue logic. While testing it on a prototyping board, I noticed that it gets warm to the touch almost immediately. I checked that no outputs were short circuited, but I also knew many inputs were left unconnected.

ATF16V8 is a CMOS circuit and I read that floating inputs can be an issue with this technology, unlike with TTL. Could this be the cause of the heat output and why?


texts:
I am trying to design electrical wiring for a small 1-bedroom house which will be only powered from solar panels. The minimum appliances in a house would be:
Appliances available in 12V DC:

LED lights
Ceiling fans
Washing machine
Refrigerator
Air conditioner
Mobile phone charger
Water pump for overhead tank

Appliances not available in 12V DC (so far)

LED TV
Laptop/sesktop computer

Some of these appliances are available for DC solar power but not all. Also solar panels and battery combinations are of different voltages as 12V, 24V, 48V etc.
How should I do the wiring design?
Only DC wiring all over in the house while using small 220V inverters at the points where 220V AC appliance is to be connected OR do all the normal AC 220V wiring in the house while connect a big central inverter 220V AC at the point where I will put the batteries and solar panel wiring cabinet?
OR maybe mix of the two wiring?
Normally the DC wires have less resistance and size is 10mm copper wire while AC wire is 3/29 or 7/29 imperial guage wires mixed-copper (called china copper) used in my region.
The house will be outside city where there is no mains electric supply or grid.


texts: Switching setup to reverse B2B charging direction

texts:
Say I have 2 of 400AH 12V DC battery banks, "A" and "B", and bankA is mobile, opportunistically charged by a HO alternator, the bankB is stationary, charged by a genset and topped up by a large solar array.

Sunny weather and alternator usage are both highly variable, there is usually no source of mains power, and a primary goal here is to minimize use of the fossil fuel engines.

When one bank is getting much more "free power" input than the other, they can be connected by a 180A "battery to battery" charger, but this unit is expensive, and is designed to charge in one direction only, from bankA to bankB.

I would like to install a switching arrangement to be able to swap the input & output wiring on the converter/charger, so I can direct current in the other direction, charging bankA from bankB when appropriate.

Ideally with a single throw, but if such a switch does not exist, I at least want a sequence simple enough to be able to train newbie users. The setup MUST protect from inadvertent direct "combining" of the two banks other than through the B2B charger, or at the very least, make doing so difficult given clear posted instructions.

The HD marine switches (from e.g. Blue Sea http://assets.bluesea.com/files/resources/sales_sheets/6823.pdf) are ideal electrically and IMO cost-effective, but the choices there are limited.

Perhaps something could be constructed from these three available designs?

ON/OFF

3-position selector: OFF/1/2

Dual Circuit, isolated from each other, both ON or both OFF

I'm pretty sure the remaining two options are useless here:

Dual Circuit plus COMBINE

4-position selector: OFF/1/2/COMBINE


texts:
http://www.datasheetarchive.com/dlmain/Datasheets-30/DSA-599035.pdf

The above datasheet is useless to me. (I do know my way around a datasheet somewhat, though)

1) Can someone explain how the heck you operate this thing?

2) Can this thing source current?

3) I see the data and clock pins, but where's the latch?


texts:
The display is a scrolling LED sign which looks like this:

It is also distributed in the US by Grandwell (SLC16H-IR). The messaging software that it comes with does not allow full control of the sign (On/Off, display different files, ect). It comes with a remote control that can do these functions, but I want to use it for an embedded application and this just won't do.

If anyone knows how to dump the Flash memory on this processor, SyncMOS SM89516A, then I can add some function calls to the software and get the control that I want (for the price I want). Any ideas? I'm exploring the MSM9042 ISP Download Board from the SyncMOS website, which may or may not work.


texts:
My university owns a Teseq NSG4070-35 conducted immunity measurement unit, including a 6dB attentuator and M3-CDN.

In the handbook and datasheet of the device it says that the power meter is sensitive and can be damaged above 27dBm. However, when one calibrates the test scenario for EN 61000-4-6, the power meter measures the signal coming from the AE-Port of the CDN that is connected via the attentuator to the amp out port of the NSG4070-35.

Access to datasheet:
http://www.teseq.com/products/NSG-4070.php, under downloads

I have calibrated the device successfully for low voltages, but now i would like to test it for 30V conducted immunity.
In the calculation of test levels, it says that the voltage levels at U=30V are 1/6 of the test levels, meaning 5V which calculates to 26.95dBm in a 50 Ohm system. In the datasheet, it says that the power meter input should not exceed 27dBm, the absolute maximum rating is 28dBm.
Can anyone tell me if another attentuator is needed or if i am fine? What i don't get is that a 6dB attentuator is used anyway, so i should not come close right?
And in the datasheet it is said, that the NSG4050 in varaint -35 can only measure levels of up to 19V with a CDN. If that is the case, can the power meter input still be destroyed?


texts: How to arrange RS232 with relays and other circuit parts to light a bulb or move a motor? I initially used micro-controller (arduino) to provide RS232 input and use the output from arduino to do tasks but as arduino costs money is there any way to simplify this process so that a beginner can do the task without using arduino! Any simple circuit diagram or helpful content pls?


texts:
So the Coolrunner2 CPLDs have a feature called GSR or "Global Set/Reset". In the documentations I found lots of references to it but no chapter that tells me how the GSR exactly works and more important: How to use it.

Also finding examples on the net in the VHDL language wasn't fruitful.

Now I'd like to add a reset functionality to my design that lets me set the flip-flops into the same state as they are right after powering up the CPLD. GSR seems to do exactly this.

Can anyone shed some light on how to use this feature from a VHDL project?


texts: simplest digital voltage selector circuit using common parts

texts:
I found the following circuit for the atmel AT89LP4052 microcontroller programmer, but the bottom right section with all those transistors is an awkward way (to me) to make the input to VPP zero, 5V, or 12V. At least the chip manual dictates that one needs to apply 0, 5, and 12V on that pin at different times to make the programming successful.

This circuit came from: http://www.gms2000.de/minimikro/LP_PP_prog.htm

So I am trying to make something simpler, so I came up with the following circuit idea:

I will hook up the A and B lines to outputs of a latch (from a 74HC series IC) controlled by the parallel port.

I'm curious, Will my setup work successfully, or Do I need to add resistors or something between the regulator outputs and the multiplexer inputs?
I also specifically chose a cmos regulator part because I think they can work with up to 15V but the highest I would feed through because of the regulators is 12VDC.


texts:
Are there any tools for selecting commercial Operational Amplifiers by filtering the results with some characteristic (not only bias current and input offset voltage bat also for example the input offset voltage temperature drift)? In my experience the best I have found is Mouser website.
Thanks all.


texts: What language is Cadence's Emanger *.ecom files written in?

texts:
I know this is a long shot but I thought I would ask while I am waiting for the FAE to get back to me. This is related to Cadence Verilog simulations and regressions.

I am trying to debug an *.ecom file and I am not sure what language it is written in. Here is a sample of the code:

var vsofs : vm_vsof = vm_manager.read_session("<1>");

// create context
var sessions : list of vm_attribute_container;
sessions = vm_manager.get_all_sessions().as_a(list of vm_attribute_container);
var curr_context : vm_context = vm_manager.create_context({sessions}, "session_stats");
curr_context.export_to_csv(RUNS, "<2>");

And this script is invoked like this:

 > emanager -b -c "setup; @create_csv.ecom \
   ../vsof/smoke_regr.user.11_03_11_16_15_52_7509/chip_passing.vsof \
   ../vsof/smoke_regr.user.11_03_11_16_15_52_7509/"

PS - If there is a better stackexchange place to put this question let me know.


texts: Clapp oscillator PCB not working when ground pin is connected

texts:
I have designed a Clapp oscillator working at 25MHz. The catch is I designed the circuit to be a part of frequency compensation network. So, I incorporated a few reverse-biased varactors whose capacitance can be varied simply by a separate DC tuning input. The first figure is the schematic of the circuit. The second figure is the PCB of the oscillator. Red wire is the DC supply input, black is the ground, and blue is the DC tuning input to the varactors.

When I connect the ground (black) wire to the actual ground (neutral) of the supply, I read nothing from the oscilloscope. However, when I leave the ground wire open and make the ground connections through the blue wire, I see a very decent 25MHz sine wave. Note that (-) of the DC supply is always connected to the neutral.

One thing apparent to me is, even though I do not connect the black wire and leave it open, it is actually connected to the ground through the oscilloscope. There is a ground plane underneath and vias connect ground traces together.

Why do you think this might be the case? LTSpice simulation works just fine by the way. Transient analysis as well as a S parameter analysis show oscillations at the required frequency. Also, I replaced all the varactors with a simple 39pF cap but changed nothing. Circuit only works when the apparent ground is not connected.


texts: Laser-Doppler Velocimetry. Math/measurment problem

texts:
My team of 3 were tasked to measure the speed of a disc with a small hole on it using laser-doppler velocimetry (measurement and sensor technology class).

After doing the measurments and writing them down, we were followed by some exercises about measurments and error calculation of the recieved data. The exercise i am having trouble with is:
"Calculate the angular motor speed (in rpm) with the help of the calibrated LDA from a differential measurement with distance ΔR = 10 mm."
Relevant data:
n1 (set speed of motor) = 1000 rpm.
fd1 (first doppler frecuency) = 530 KHz.
fd2 (second doppler frecuency) = 627.5 KHz.
So I know the formula to calculate the speed in rpm in this situation is:
n = (distance of strip where the 2 lasers colide, or delta x)(doppler frecuency fd) / 2pi*(Radius from center of disc to center of aperture: R = 55 mm).
However i cannot use this because my radius is unknown. I only know the difference between 2 of my radii. I tried to adapt this formula for it to be useful to me (foto), but it´s still pretty confusing for me to use. Has anyone had any experience with laser-doppler velocimetry that could help me out here please?


texts: How to make an USB keyboard work with Bluetooth instead?

texts:
I have an USB keyboard (HHKB) which has some great irreplaceable features(That's why I would not like to buy a Bluetooth keyboard directly) and I love to use it very much. But the only improvement I expect is to avoid its USB wire. I would like to connect it to my laptop(a Macbook Air) wirelessly with Bluetooth.

I have searched the Internet but found only a little pieces. I still don't know what I need to prepare and how to do it. Is there any small device which can be plug into the USB port of my keyboard and convert it to a Bluetooth keyboard? If there's not, how can I make one by myself?

Thank you!


texts: Baud rate for at89c2051 using 24 MHz oscillator

texts:
What is baud rate of AT89C2051 using 24 MHz crystal oscillator in Timer 0 mode?

I have seen this post about calculating baud rate of microcontroller but I don't understand it.

How to find / set baud rate in AT89C2051?


texts:
I am trying to get a handle on some electrical circuit diagrams I've been encountering as I try to get back into electronics and building electronic gadgets. I've encountered a number of terms for voltage, and I am not sure what they all mean, so I was hoping someone could explain them to me. Here they are, along with what I believe they mean (if I think I know):

Vpp (Voltage peak power?)
Vp
Vcc
Vc
Vr
Vdd
Vi
Va
Vt
V0 or 0V (Negative or common "terminal", source of lowest potential?)

There are also the common Vin and Vout designations, which are pretty self explanatory. I've also seen positive and negative voltage indicators in AC circuits, but that is also self explanatory.

Are some of these simply context specific, with meanings only valid within a given circuit? Are they all commonly used?


texts: LED blinking with capacitor and schottky diode?

texts:
I saw one circuit which connected one 100uF capacitor and one schottky diode as mentioned in the below circuit diagram. It has a negative logic rectangular pulse at cathode of the LED, which is providing ground for the LED.

I tested that circuit but I was not able to understand why they used a capacitor and schottky for this circuit for LED blinking, even that the LED can blink directly if we connected VCC to the LED anode. I attached one screenshot of the oscilloscope:

Node B  is yellow signal
Node A  is green signal

What is the advantage of this circuit?
Is that giving more voltage variation for the LED to turn on?
Is that a LED flashing circuit?
Is it increasing the brightness of the LED?

After reading the all comments I had one idea, that it might be an LED Brightness circuit.

For that I closed all light of my lab, took a close picture of led, which I am going to share with you.  I don't know if it is a right answer but it is quite enough to say it is a LED brightness circuit.


texts: HSR412 (solid state relay) parallel circuit connection not working?

texts:
So I got some HSR412s and connected them to my Christmas lights in a serial circuit. It worked great and as expected except for one caveat.... It was getting really hot. I realized I was putting double the rated current in and decided to go with a parallel circuit which could take more current.

I hooked up the wires like the picture said and when I plugged in the lights, they turned on, which is not what they should do when connected to these relays. I also tested to see if a parallel connection would turn the relay into the nominally open type, but that also was incorrect. I had my 6 and 4 pins connected to positive power in a Y split and had my 5 connected to the lights. I may have a misunderstanding of how a parallel circuit works but have no idea where I went wrong, and why the relays aren't working under my wiring. The datasheet is here.


texts: I have a relay which is electronically controlled by a computer (Odroid) and used as a switch for a high power circuit. The computer and the other circuit are powered with different plugs on the same multiple socket. When the relay opens the circuit, there are some issues with the computer (for example, some USB devices are not recognized anymore). Can this problem be related to the socket? How can I prevent it?


texts: lithium ion battery in series discharging question

texts:
Trying to connect 4 12V 5Ah lithium ion batteries in series to make 48V 5Ah source.

If my circuit is running on lower amps than 5, lets say 1A.

Is the batteries going to be fully discharge in 5 hours with a stable 48Volt or is one battery at a time going to be fully discharged one at the time?


texts:
I am looking for a connector that is circular, can be turned when in contact and can carry 5V/GND/2 data lines. The headphone Jack is the perfect solution. It has 4 contacts (can be less), it is circular and it can be turned when inserted.

This fits my needs perfectly. However my application is nothing to do with audio and I would have preferred something more custom so that people don't stick their headphones to my product. Are there other alternatives? I searched but couldn't find out.


texts: Can I use 16V power adapter for scanners that need 12V?

texts:
Possible Duplicate:
  Choosing power supply, how to get the voltage and current ratings?

Will they be damaged? The two HP deskjet 2400 and 4300C scanners need 12V, 1.25A as I read. I only have a 16V, 3.36A power adapter with the connector they require.
Will I break them?


texts: Different number of bit for the ADC and DAC linked to a \$\mu\$controller - Electrochemical sensor

texts:
I am studying an electrochemical sensor (see figures below please) where the number of the bit of the DAC (Analog Devices AD5685R) is 14, whereas the number of the bit of the ADC (Analog Devices AD7682) is 16. The \$\mu\$controller (Microchip dsPIC33EP256MC204) can handle 16 bit data.

The potentiostat is the following:

Why did the designer choose a 14 bit DAC, instead of a 16 bit DAC?

I took the above sensor from a paper; in it there should be the necessary information to understand the reason of the choice, but I do not find it.


texts: I have question about adc differential input. Are they not suppose to be positive and negative? Than you get the benifits of differentials signals. In the circuit illustrated the differential input output voltage amplifier. Both of outputs are positive, so advantage what advantage does this circuit have than?


texts:
I have this electronics that uses 3V rechargeable coin cell battery (ML2032) to power the RTC when the system is off. When the system is powered on it'll trickle charge the battery instead.

I'm looking for ways to allow the usage of regular non-rechargeable CR2032 battery instead. One way I see people doing on Amiga, which also uses 3V rechargeable battery, is to simply add a Schottky diode in series. However, I wonder if there is something even better. To me a voltage drop of at least 0.15V is a lot for a 3V battery.


texts:
I have an application where I am trying to monitor a defect in a web based manufacturing process.

This defect can be seen if one side of the substrate is lighted and the transmitted light is viewed from the other side.  When the defect occurs a change in the transmitted light is noticed.

I am looking for a commercial sensor which I can use to give me an analog signal.

I also want to experiment with a sensor on a breadboard to get an understanding of how a change of light translates into an electronic signal.

My application will require a very low response time as the speed of my process will result in the defect being in front of the sensor for less than a millisecond.

Any direction on sensors or components will be appreciated.


texts: Eagle polygon border segmentation around pads / vias / holes

texts:
Why in Eagle, polygon border near pads / vias /holes are segmented? Why it is not pure circle (or following shape). Is there any setup where this can be changed?

EDIT:
Here is example where DIP via is isolated with only one connection (easier soldiering) and with thermals. Polygon around isolated via is segmented, with thermals not.


texts: AT commands no answers ! SIM808 and Arduino

texts:
I will try to explain my problem...
I'm using a SIM808 GSM-GPS click module and a ARDUINO nano 33 IoT board,
I'm sending the command "AT\r" thanks to the TX port from the ARDUINO board to the RX port from the SIM808. I have checked the signal thanks to an oscilloscope and he is corresponding to the the command.
But now when I'm checking the answer on the TX port from the SIM808 there is absolutely nothing ...
Normaly I have to received "OK" ...
Please HELP ME !!!
I'm using my ARDUINO in NL&CR and baud number is 115200.
You can find bellow my Arduino code:
String incomingByte; // for incoming serial data;
String returnByte; // for outcoming serial data;

void setup() {
  // initialize both serial ports:
  Serial1.begin(115200,SERIAL_8N1);
  Serial.begin(115200);
  delay(1000);
}

void loop() {
// send data only when you receive data:
  if (Serial.available() > 0) {
     while(Serial.available()!=0){

// read the incoming byte:
    //incomingByte = Serial.readString(); // In comments for only try with "AT\r"
    //Serial.print(incomingByte); // In comments for only try with "AT\r"
    //Serial1.println(incomingByte); // In comments for only try with "AT\r"
    Serial.println("AT\r");
    Serial1.print("AT\r");
    delay(10);
    }
    Serial.flush();
   }

//read the outcoming byte:

   if (Serial1.available() > 0) {
     while(Serial1.available()!=0){

    returnByte=Serial1.read();
    Serial.print(returnByte);
    }
    Serial.flush();
    }
  }


texts: Measurement of total AC resistance (including radiation resistance) of a coil using LCR meter

texts:
If we measure AC resistance of a coil using an LCR meter (or impedance analyser), does it include both ohmic resistance and radiation resistance? I understand that the radiation resistance is negligibly small for coil at low frequencies, however, for example, if we submerge a coil underwater, radiation resistance can be comparable to ohmic resistance.

I am measuring resistance of a coil underwater and I noticed a significant increase in resistance compared to the air surrounding. I wanted to confirm that the increase is due to the increase of radiation resistance. Maximum frequency is 1 MHz, and coil self resonance is way above the measurement range - we can safely neglect the effect of parasitic capacitance.


texts: Do small 1:1 isolation transformers exist?

texts:
I am building a Nixie clock that will be powered from 110V wall power. The design is based around having this 110Vac as the input voltage, but I wanted to put an isolation transformer inline for safety.

This thing will maybe go up to 10W, so I don't need a huge high power transformer. But I cannot find a 1:1 small transformer. Are these not a thing? Am I looking in the wrong place? Or do I need to redesign my circuit to use a different input voltage?


texts: Does merging the chip and the contact pad in a chip-and-pin card make the whole module less reliable?

texts:
This picture is from here (A and B letters are irrelevant for this question). A chip-and-pin card like Visa Electron has a contact pad like this on its face side:

Underneath the contact pad is the chip which has electrical connection with the contact pad. The pictures I found so far suggest that it's a single module - the chip is mechanically united with the contact pad and is then installed into a plastic card.

The contact pad is perhaps ten millimeter wide and ten millimeters long and so much larger than the chip surface. When a card is being bent the contact pad also bends and this most likely causes the chip casing to bend which causes mechanical stress of the chip. Mechanically stressing a chip doesn't sound like a good idea.

How is this problem addressed? Does merging a large contact pad with a smaller chip into a single module make the whole assembly more reliable or more fault-prone?


texts: How to make the connections to the 1 channel optocoupler relay module?

texts:
I want to light a bulb connected to the socket by using an 1 Channel Optocoupler Relay Module which accepts an input of 5V.

From my understanding, when the modul receives DC current (5V), it's going to turn on the other circuit and turn on the bulb.

I'm not sure how to connect the module in this context.

It looks like this:

    +----------------------+
    | 10A 250VAC 10 125VAC |
DC+ – 10A  30VDC 10  28VAC – NC
DC- –                      – COM
IN  –                      – NO
    | SRD-05VDC-SL-C       |
    +----------------------+

It didn't came with any documentation, so I'm not sure what these notations mean.

I assumed I have to connect the positive wire from the 5V circuit to DC+ and the negative/ground to the DC-. I'm not sure if this is correct.

However, I don't understand how to connect the wires at the other end.

I have no ideas what IN, NC, COM and NO mean.

Is there any place where I can find the documentation for this kind of relay or are these universal notations? What do they mean?

How should I make the connections?

The module looks like this:

So, I connected the bulb wires to COM and NC and the bulb is turned on when I connect it to the socket. Then I tried connecting a battery to the DC+ and DC- and the power led of the relay component is turned on, but the bulb is not turned off.


texts:
I am a little confused on how capacitors and inductors act when t=0.
For example lets say we have the following circuit:

Is(S) = 8/(s+2)
Whats the current I(L) at t=0?
What if the inductor was a capacitor, Would it change the current at I(C)?
EDIT:
After some reading, I think your supposed to treat the circuit as a DC circuit at t=0.
Then I(S) = 0 A
an inductor would act as a short
a capacitor would act as open.
If the circuit above has an inductor then I(L) = 0 A
If the circuit above has a capacitor instead of inductor then I(C) = 0 A


texts: Dynamically change PWM frequency with interrupt with STM32

texts:
I'm using an STM32F4 to control a stepper motor.

I'm not sure if I need PWM mode or OC Mode or OnePulse Mode. I can generate a fixed frequency PWM wave but since I need a particular acceleration/deceleration, I need to vary the frequency of the wave with a ramp.

Something like: one pulse at 745 Hz; one pulse at 1867 Hz; one pulse at 2459 Hz; one pulse at ...; one pulse at ...; N pulses at ... (constant speed)

Right now in the callback HAL_TIM_PWM_PulseFinishedCallback, I'm issuing new TIMx->ARR and TIMx->CCR1 values based on a given logic.

Here is my code:

void MX_TIM9_Init(void)
{
TIM_OC_InitTypeDef sConfigOC;

htim9.Instance = TIM9;
htim9.Init.Prescaler = PSC; // Get clock to <freq> Hz
htim9.Init.CounterMode = TIM_COUNTERMODE_UP;
htim9.Init.Period = 1582; // useless since it is varying
htim9.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
HAL_TIM_Base_Init(&htim9);
HAL_TIM_PWM_Init(&htim9);

sConfigOC.OCMode = TIM_OCMODE_PWM2;
sConfigOC.Pulse = htim9.Init.Period / 2; //useless but always 50% of CCR1
sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
sConfigOC.OCFastMode = TIM_OCFAST_ENABLE;
HAL_TIM_PWM_ConfigChannel(&htim9, &sConfigOC, TIM_CHANNEL_1);

}

void HAL_TIM_PWM_PulseFinishedCallback(TIM_HandleTypeDef* htim){
if (htim->Instance == TIM9){
    // logic
    TIM9->ARR = v;
    TIM9->CCR1 = v/2;
}
}

int main(void) {
//other
MX_TIM9_Init();

//logic and if needed
HAL_TIM_PWM_Start_IT(&m->htim, TIM_CHANNEL_1);
}

What I'm noticing is that the wave train is not perfectly shaped as if the Update Event that update the shadow register happens sporadically. If I'm expecting one pulse with 500 Hz and a second of 700 Hz that doesn't happen. Clearly a constant frequency wave at 500 Hz and 700 Hz is generated correctly. I tried to SET-RESET an output to verify at which point the interrupt is called.

When it fails it seems that an interrupt is called when the PWM is still "high."

Is the PWM the right way to do it or should I use OC or OnePulse mode?


texts:
Started a new job writing software for a company that does some power metering and I'm trying to wrap my head around this whole phase rotation thing.

So, I understand there are 3 phases and they can be in two different orders (ABC/CBA or ABC/ACB depending on the convention you prefer).

In my specific case, I have a power meter that might spit out the following:

Iaɵ - 341
Ibɵ - 223
Icɵ - 103
Vaɵ - 0
Vbɵ - 240.8
Vcɵ - 120.8
PFa - 0.95 capacitive
PFb - 0.94 capacitive
PFc - 0.95 capacitive

The goal is to draw a phasor diagram to properly represent this data.  I wrote something quickly to generate this:

However, I am being told that the rotation on this is incorrect by one of the EEs on staff and that he can determine this simply by seeing that the power factors are listed by the meter as capacitive rather than inductive.

Anyone able to explain to me exactly how to plot these values correctly and how exactly ABC vs CBA rotation plays into plotting the phasor diagram in the correct manner?


texts: How to light an LED using supercapacitor

texts:
I would like to light up a 3W LED from Cree having a forward voltage of 2.9 V at 350 mA. It's maximum drive current is 1 A and gives 300 lumens/m2 output. I am considering lighting up this LED using supercapacitors.

  The objective is to light the LED for 5 hours.

Based on this objective, I tried to calculate the capacitance required in reverse using the following formula:

(Energy stored in the capacitor)/(Power of the LED) = Time required for the LED to glow)

Additionally, I came to know that If a switching circuit is used, the losses for the supercapacitor charging operation would be less as a resistor dissipates 50 percent of the input energy. If the voltage drop across this circuit is 1 V, then taking this into account as well, I obtain:

\$\frac{\frac12 C V^2 - \frac12 C 1^2}{1.05(P_{led})} = 5\text{ h}\$

As the supercaps are generally rated at 2.7 V, I substitute V to be 2.7 and obtain the capacitance to be 18270 F which is extremely high. I needed to cross verify the theoretical capacitance required to get this LED to glow for 5 hours is right or not.

If I go for a 2.7 V, 500 F supercapacitor, I am obtaining the LED to glow for 30 minutes.

From what I have read about the supercaps, the charging rate is quite high for the supercaps, and assuming that I am generating electricity simultaneusly to charge the supercap and simultaneously light the LED, Would it be feasible?

I am imagining the 2.7 V 500 F supercap as a big tank with an inlet and an outlet. The inlet is quite high because of high charging rate whereas the outlet rate is slower. The inlet rate is 5 W and the outlet rate is given to the 3 W LED.

I am giving a 5 W power input using the right switching circuit to feed it into the supercapacitor. If this is the case, would I be able to instantaneously light this LED. If not how? What would be the right circuit I should implement to use it as a buffer.


texts:
I have to build a circuit of an arithmetic right shift operator in verilog and include it in a verilog code of a simple computer. I've written the code of the circuit with a module and it compiles without an error but when I try to include it in the code of the computer(it has to be in an if-statement) an error occurs: "error: syntax error, unexpected MODULE" is it possible to include a module in an if-statement?

 always @(alu_A or alu_B or aluop)
if      (aluop==0)    alu <= alu_A;
else if (aluop==1)    alu <= alu_A + alu_B;
else if (aluop==2)    alu <= alu_A - alu_B;
else if (aluop==3)    alu <= alu_A & alu_B;
else if (aluop==4)    alu <= alu_A ^ alu_B;
else if (aluop==5)    alu <= alu_A << alu_B[3:0];
//else if (aluop==6)    alu <= right_shift(alu_A, alu_B[3:0]);
else
 begin
 module right_shift (alu_A,alu_B,alu);
input [15:0] alu_A;
input [3:0] alu_B;
output [15:0] alu;

this is a piece of the code: the comment is the old piece of code where right shift is done everything beneath are the changes i've done. I did not comment the whole code because it is very big


texts: Can connecting of AC adaptor first into device, then into mains pose a risk of voltage spike?

texts:
Manuals of several various electronic devices I came across recommend connecting their AC adaptor first into the device, then into mains. I always thought the reverse order is safer because I thought that connecting into mains can send a voltage spike into already connected device. Are power supplies (adaptors of laptops or other electronics) designed in a way that there is no risk of harm to their device when connecting?
Are both connecting orders equally safe in these terms?


texts: I have one central 300w power supply running at 5v. How can I split this into 3 equal "ports" that use 20amps each

texts:
I have one central 5v 300w power supply. I want to basically split the power among 3 different ports instead of blowing the whole 60 amp load. How can I share the power evenly.

Thanks!


texts: Delayed VCC rise time with Parallax Smart Card Adapter

texts:
While implementing a T=0/1 protocol using a smart card reader I had obtained from Parallax, I noticed a behavior when applying power to the card. It seems that once the 3.3v VCC pin is brought high, it has a greatly reduced rise time (on the order of 450us).

The 450us timing was taken with no smart card inserted in the reader, and only VCC and GND connected. An oscilloscope was connected to VCC. VCC was applied and the rise time was recorded.

I believe this to be the result of the decoupling capacitor at least, but I'm not certain how the pull-up resistors on CLK and IO might also be contributing (if at all). The capacitor is a low ESR ceramic cap.

I also tried an isolated circuit with a 1uF, 10uF, and 100uF decoupling caps and was able to simulate extended rise times on VCC moreso with the 100uF cap. That leads me to wonder if there's more at play with the smart card reader circuit, like the pull-ups.

My question: Is the increased rise time the result of the decoupling capacitor and/or the pull-ups. If so, how can I best calculate this time, rather than observing it.


texts: Hydrogel and silicone compatibility to conduct NMES device

texts:
I have a question in regards to a neuromuscular device. Can silicone be combined with hydrogel or the rubber silicone encased in hydrogel to form a wrist watch strap combined with a NMES device. If this is possible how would the hydrogel conduct the NMES device and what is the durability of having encasing of the hydrogel around the silicone and the durability of combining the two together?
Any help would be greatly appreciated
Anna


texts: Only charge capacitor when button pushed then turn on 12 VDC motor momentarily with capacitor when button released

texts:
Can I turn on a DC motor momentarily with this circuit if I replace LED with 12 VDC motor?

I need help making a circuit to turn on 12 VDC motor momentarily with push button. So if I push button, the 12 VDC motor not activate, but when I release it the DC motor will be active momentarily; what should I do?


texts:
When wiring a 3 phase AC motor I need to connect 3 phase lines and neutral from the 3 phase socket to the motor. Motor has 3 lines and a ground symbol on it to power up. But the socket is 3p+E+N socket. I cannot determine which is earth which is neutral. Does that matter? Are they(neutral and earth) internally connected. Here is the socket:
http://www.distributionzone.com/store/industrial-plugs/product-straight-plug-3p-n-e-400v-63a-ip67-035-6-41/


texts:
I'm blanking out on a name for something about current source circuit B in this imageSomewhere, i

Somewhere in some forum thread in the last year there was a discussion about errors in current source circuits.  IIRC there is a mod to circuit B that adds a resistor in series with one of the bases.

Is this in fact a known fix to reduce the effects of xxx (base current, temperature drift, whatever)?

Does the error effect or this correction have a name, like "adding the resistor reduces the Wolfgang effect".

Update:  Vague memory of it being some kind of effect that had to do with the transistor itself, maybe beginning with an "E" - ?
Thanks.
ak


texts: What connector is this on HP 463172-001 fan?

texts: It's a fan from an HP ProLiant server, what connector does it use?


texts: How is USB-C able to be used for DisplayPort, Headphone jacks, OTG etc?

texts:
My smartphone has a USB-C which can be used with several adapters to drive displays via DisplayPort, headphones via 3.5mm jack, and connect to other devices via master OTG or slave mass storage.
My PC has a USB C port which can be converted to a DisplayPort (although internally connected to the integrated graphics on mine, it seems), and I think there are many other uses.
How is USB C able in practice to be so polyvalent?
Do all the converters communicate with the port using a single protocol like HID to register their type and bring up the appropriate driver and message format? How is it implemented roughly?
How is USB C able to route high speed video signals from graphics cards with minimum latency while being multiplexed for other uses?
In a nutshell, anyone care to explain  this black magic trick that is USB C without asking to read hundreds of pages of documentation?
P.S. I'm at the right place, I'm looking for an answer on low-level Comms and electronics/IP architecture


texts: If I wanted to control several ICs that exceed the current rating of an Arduino 5V supply pin with an external DC regulator (which also would power the Arduino itself), should the ground planes of the DC regulator be be connected to the Arduino GND pins?


texts:
Here I've issue related to DS1621 digital thermometer interfacing with PIC18F26J50 controller.
Below you can see my code and this code I build in MPLAB X v.1.4 IDE with C18 compiler:
 unsigned char i2c_read(void)
 {
    char buf[20];
    unsigned char i,j;
    j=0;
    i=DATA;
    for(i=0;i<8;i++)
    {
        j<<=1;
        CLOCK = HIGH;
        j|=DATA;
        delay_ms(100);
        CLOCK = LOW;
    }
    //////////////////////
    **sprintf(buf,"%d",j);    // 255
    transmit_str1(buf); //UART transmit string**
    /////////////////////
    return buf;//return j;
  }

main()
{
while(1)
{
    i2c_start();
    i2c_write(0x90);
    i2c_write(0xAC);
    i2c_write(0x02);
    i2c_stop();

    i2c_start();
    i2c_write(0x90);
    i2c_write(0xEE);
    i2c_stop();

    i2c_start();
    i2c_write(0x90);
    i2c_write(0xAA);
    i2c_start();
    i2c_write(0x91);
    ch = i2c_read();
    i2c_stop();
 ///////////////////
     temperature = 0;
     convert(ch); //convert binary to Decimal

     if(flag==FALSE_)
     {
         flag = TRUE_;
         tmp=temperature;
         //itoa(tmp,buffer);
         sprintf(tmp,"%s",temperature);
     }
     else
     {
         if(tmp!=temperature)
         {
             tmp=temperature;
             sprintf(str,"%d%s",temperature,"Centigrade");
         }
     }
   }
 }

Here I'm interfacing DS1621 Thermometer with PIC18F26J50.
and I'm doing I2C communication between them.
and I see this result on UART,  but I get "255" data.
This "255" data string I got from "i2c_read(void)" function.
Here I'm attaching a screenshot of Oscilloscope from Proteus software.
(YELLOW: SDA  |  BLUE: SCL).
Can you please tell me how to get reading from DS1621?


texts: LTSpice AC analysis and DC analysis don't agree?

texts:
I have a simple circuit pi circuit.  When I do the math and subsequently run the simulation on LTSpice, I get a similar answer - the resonance occurs at f= 217447Hz (math), 217450(LSpice).

The error log shows the following measurements:
.meas AC maxVout MAX mag(V(vout))
.meas AC resFreq when mag(V(vout))=maxVout*.99999999
.meas AC BW TRIG mag(V(vout))=maxVout/sqrt(2) RISE=1 TARG mag(V(vout))=maxVout/sqrt(2) FALL=last
.meas AC resQ PARAM 10^((resfreq/(bw))/20)    **this result is in decimal, but displays as dB in the error log file.

When I run a transient analysis, with the voltage source set  up as sine wave as $$ 1\cdot Sin(2\cdot\pi\cdot 217450\cdot t)$$, my expectation is the that output at node vout would be around 8.33V (10^(18.4138/20)volts).  However, the output of the transient response, the maximum amplitude of vout is around 2.1V volts:

What's going on?  Has anyone else run into something like this?
To check, I used Mathematica to plot the time domain output of my circuit's transfer function (convolved with the input sine wave source -ie, set Vin in my transfer function as a sine wave of frequency 217450 in the laplace domain, and then took the inverse laplace), I get something like I'd expect:

I don't know why LTSpice is not giving me the same answer ---I must be doing something wrong.


texts:
I am using schematic to controll a bldc motor without sensors.

As gate drivers I am using IR2101 and also I added some diodes in anti-parallel with gate resistors (not shown in the schematic)
I am trying to drive the motor in the start sequence like a stepper motor. At this moment I am testing this with an arduino uno.
The motor control works fine but the MOSFETS get too hot.
For a phase (B) I have  the gate signals like in this picture, but the motor is not powered. (Yellow - high side, green - low side)

When I connect the motor it spins well, but the MOSFETS get too hot. And the signal present at the gates for phase B is like this. (Yellow - high side, green - low side)

The motor is a 36V,250W bldc motor.
Does anyone know what could be wrong ?


texts: Is there a derivation of the Early effect?

texts:
I can't seem to find a derivation of the following equation:

$$I_C=I_Se^{\frac{V_{BE}}{V_{T}}}\left(1+\frac{V_{CE}}{V_A}\right)$$

Is there a way to derive this equation?

Edit: The equation describes a bjt transistor, so I have included a bjt. Also a plot of Ic against Vce to demonstrate the early effect.


texts: What is the origin of the "iso [frequency/voltage/power]" terminology?

texts:
In the VLSI and computer architecture world, it is common to hear terms like "iso frequency" or "iso power" when comparing the performance of different designs.
My understanding is that "iso" here means "at the same"; e.g. discussing the performance of two different designs "iso frequency" means discussing their performance when run at the same frequency (controlling for any frequency differences between the designs).
Where does this "iso" terminology come from? Is "iso" an acronym ("ISO"), or is it shorthand for something else?
I heard this terminology used several times during the Q&A and discussion at HotChips 2020, but it is hard to find references to it on the internet and clues to the origin and meaning of "iso".


texts: Scope reading changes with amplitude scale

texts:
I have a low frequency (70Hz) sine wave being measured by a 1x probe on a (lower-end) Siglent SDS1052DL, and I get a roughly a reading I expect.  However, when I change the amplitude scale, the reading changes as much as 5%: 1.22Vpp at 200mV divisions, 1.28Vpp at 500mV div, 1.30Vpp at 1V div, 1.36Vpp at 2V div.  I hear an audible 'click' when changing from 200mV to 500mV scale, so I am assuming the circuitry is changing in that case.

Is this normal for lower end scopes?  It matters when trying to do things like accurately measure the output impedance of a sig gen.


texts: What do the TXRB bits do in the CiTXnDLC registers of a dsPIC 30F?

texts:
The family reference sheet for the dsPIC 30F line, page 23-7, describes register 23-5 CiTXnDLC. (Page 627 of the PDF linked here.) Bits 8 and 7 are labeled TXRB<1:0>: Reserved Bits, with the note "User must set these bits to ‘0’ according to CAN protocol."

What are these bits? Why are they settable if they are expressly never to be set? What happens if they are set?


texts: Will brushless fan speed depend on amperage?

texts:
I am not a technical guy and have no knowledge in electrical subject.

I use brushless fans in my regular day to day activity. We use them for pellet stoves and hence my question:

Will amperage rating of brushless motor decide RPM of the motor ?

What is the best brushless motor to run continuous for 8 hours, both on battery and direct power, in stoves ?

Brushless fans rated for 220v and 1 amp motors are used up till now. They are not providing enough pressure for fire and getting useless within 100 hours of usage as these motors will attract heavy heat from stove body.

Please suggest the solution for the same.


texts:
I have to design a sequential circuit for a traffic light controller. It has 6 outputs, Red-Green-Yellow for North/South and East/West lights. What has to happen is that every 8 clock cycles (one clock cycle is represented by 1 button push, so after 8 button pushes, the lights switch) the lights have to change. So, the order would be

R(N/S)-R(E/W) -> R(N/S)-G(E/W) -> R(N/S)-Y(E/W) -> R(N/S)-R(E/W) ->
G(N/S)-R(E/W)-> Y(N/S)-R(E/W) -> R(N/S)-R(E/W) -> R(N/S)-G(E/W)... and so on.

I have created a diagram, truth table, and equations. As far as I can tell, I have everything connected and put in correctly (We're using quartus to program a DE0). I have a 3 bit register connected to the combinational circuit for my state machine.

Only thing I can think of being wrong at this is that my initial design is completely wrong. What's happening is that after 8 clock cycles the state doesnt change.

Here are pictures of my state diagram, truth table, k-maps, and equations. Ignore the min terms box. Its just a way I sort through the truth table because it is hard to read.

EDIT: What I am asking is, is my design sound? Am I fundamentally making a problem with the state diagram?


texts: Is There An Automatic Precision Screwdriver For Small Works?

texts:
I need automatic tool to work with small electronical things but don't know of any good one. I am looking for something like this but of better quality and switch but push forward/reverse button:

If anyone uses automatic precision screwdriver and is satisified with it, can please recommend me something?

Thanks.