texts: Frequency dependent impedance as an electrical circuit

texts:
I am having problems trying to custom fit a frequency dependent behavior. I want to be able to convert a frequency dependent impedance Z(f) into an electrical circuit of the sort 1. The input of the code is the frequency dependent impedance Z(f) (real or complex) and the output will contain the values of the R_1, R_2, R_3, R_4, L_1, L_2, L_3 of the equivalent electrical circuit that will reproduce the same frequency behavior as that of Z(f).
My question is: how can I compute the parameters of the equivalent model (seen in attached picture) to have the same frequency behavior as that of the input Z(f) ?
Thanks in advance.

Photo here: 1 https://i.stack.imgur.com/hunlr.png


texts: AVRISP mkII not reading device signature

texts:
I recently bought a dozen ATtiny85 MCUs and I was trying to test one simply by putting a blink program on it via the Arduino IDE with and AVRISP mkii (Arduino 1.0.5, Ubuntu 13.04). I kept getting an error suggesting that it wasn't wired correctly, but I've checked it multiple times (and it's powered externally at 4.8v). I even tested multiple ATtinys so it's very unlikely that they're all duds. When I switched to using my Arduino as ISP, it programmed fine. I tried using avrdude -c avrispmkii -p t85 -P usb -t to see if it was a problem with the Arduino IDE setup, but that gave me the same error. I set all the /etc/udev rules correctly as far as I can tell, and still no dice...

So I booted into Windows 8, installed Atmel Studio 6 and the drivers for the AVRISP mkii. I updated the devices firmware (to 1.16), and then tried to read the signature of the attiny85. This failed, giving me [ERROR] Failed to enter programming mode. ispEnterProgMode: Error status received: Got 0xc0, expected 0x00, ModuleName: TCF (TCF command: Device:startSession failed.). I tried it again, this time with the atmega328p from my arduino, and once again it failed. The ISP clock is dropped to 125 khz (and I've tried lower too). I know both the atmega328p and attiny85 are working still and the fuse bits were never tampered with (the blink program on the attiny from when i used my Arduino as ISP still runs).

Does this mean that my avrisp mkii is dead? All the LED lights behave exactly as expected (LED turns green with power is given to the MCU, red otherwise. USB LED is solid green and flashes when theres traffic). Additionally, it's recognized by both Windows device manager and Atmel Studio 6.

Thanks


texts: How do I pan in EagleCAD with an Apple MagicMouse

texts: I'm using a MacBook Pro with OS X Mountain Lion, but can't figure out how to pan the schematics?


texts: Simultaneous electronic shutter release for multiple Lumix G7 cameras

texts:
I'm trying to trigger six Panasonic Lumix G7 cameras at once.
The trigger mechanism uses a four pole 2.5 mm plug, some resistors and two switches. With no switch closed there is 41 kilohms of resistance. To trigger the focus, you reduce that to 5 kilohms. To trigger the photograph or video start you allow 2 kilohms of resistance.
So much I learnt from this great blog post: http://www.robotroom.com/Macro-Photography-2.html

Wired this way it triggers a single camera just fine. However, when you add additional cameras to the circuit, it doesn't work anymore. I'm guessing that the resistance is no longer correct, because now the focus trigger does nothing (I think) and a shutter release trigger makes one camera focus.
When I was 11 I was the proud owner of a DSE Funway into Electronics set. I'm afraid I've learnt nothing much since then.
Any way to wire this up so that the resistance is correct for all the cameras? Ideally I could add more than 6 cameras in the future following the same method.
My fall back are independent circuits with a mechanical switch closing them all independently, but 1/100 second accuracy would be a big help here, so I'd love to do it right.
Cheers,
Red


texts: RS485 network ground pin - when to connect?

texts:
As many know, one can implement a simple node to node rs485 communication by using only two wires, A and B. Well, the standard specify to connect the ground of the two node together.

from Wikipedia:

  In addition to the A and B connections, the EIA standard also specifies a third interconnection point called C, which is the common signal reference ground.

I stumbled upon tens of articles that speak about this third connection but still couldn't understand the concept.

Why can't the receiver just act as a simple voltmeter? measuring the voltage between A and B?
If both nodes are battery operated(different battery for each node) does the ground connection make any difference?
Why is it better for (outdoor) nodes to be earthed when cables are long?
How is this ground connection good for protection from transient?


texts: Making sense of Cadence schematic source files

texts:
I'm looking into writing an application to visualize existing cadence (OrCad) projects when provided with the projects design files. I've had a look through the project directories and it looks like the .dsn and .dbk files are likely to contain the information on positioning, connections and orientations of all the components but the encoding of this data is largely unreadable - to me at least!

Does anyone have any knowledge on how this data can be extracted from the project files - some examples of file segments and implied information would be great too!

Alternately if anybody is able to provide an equivalent answer for the EAGLE platform I can switch the target platform to that.


texts: High side P channel MOSFET power switch - gate question, and suggestions for my circuit?

texts:
My circuit is for switching a 12V battery to a load (LED lights, designed for automotive use), during my testing with prototypes, the lights consumed about 400mA, meaning they were ~5W LED products.

I would like some feedback on the way I've done the pull up/pull down control interface for the P MOSFET with additional LED indicator.

First, I shall describe the labels and components briefly:
BATT_ON is the 12V power connection to battery, through a automotive blade fuse and a switch (which I just realized will have to be changed so it's not a series switch.. rather for current handling reasons be another PFET pass element arrrgh..)

OUTPUT2B is my digital output from 3.3V microcontroller.

OUTPUT4 is the high power load output. The load's return is connected to the Battery negative terminal through the system's common ground. This is a standard high side only switch (the load's ground is not floating).

R1 is a pull-up resistor in normal conditions (PFET being off) and acts as a current limiting resistor for the small onboard 0603 sized LED "OP1"

OP1 small 0603 sized SMD LED used for indication that the PMOS is output is "ON"

R8 is a  pull down resistor to ensure no floating pin/noise can accidentally turn on Q3A

R7 is the base current limiting resistor.

Q3 (A because it's part of a dual NPN package) is the BJT that pulls down the P Channel MOSFET's Gate to turn it on.

Q1 the P channel MOSFET switch. A little SOT23 package whose part number and ratings are shown in the picture text.

My main question is:

When OUTPUT2B is ON, and Q3 is turned on, Q1's gate will be discharged to allow the FET to turn on - but while R1 is supplying current to the LED (OP1), will it also create issues with the gate of Q1? How can I quantify this, if it will be an issue? Will there be charge contention at the gate, leading to undesired behaviour in the Source->Drain?

Normally I would just pull the gate straight to ground in this 3.3V->12V high side switch interface, and i've done this before with no issues. In a prototype with very limited testing (and I do not have access to it anymore) I did actually implement this but never got the chance to analyse the gate behaviour.

Any comments are welcome.

From an answer and comment, these are two alternative versions:

Alternative 1
This one moves the LED and the "pull down resistor" to before the NPN's base resistor and makes the microcontroller drive the LED itself. These are merely low power indicators, so 1-2mA is all that is needed, and with up to 6 of these on at any time, cannot afford too much output.

Alternative 2
This one uses the P FET's output to drive the LED this way, through a resistor for current limiting. This is coming from battery power, so can afford to be for more powerful and than if driving from the microcontroller output pins or my earlier attempt at piggybacking off the NPN transistor interface.


texts: Interfacing PIC18F4550 with I²C EEPROM (24AA1025)

texts:
I am working on a university project in which I need to interface a PIC18F4550 with an I²C EEPROM.

I read many codes and saw many projects on this topic. And I wrote a sample code from MPLAB C18 (and I tried many codes also), but no one worked with me.

I don't know where the problem is. Everything is OK with my code and with my circuit, but the SCK signal did not generate the CLK signal for writing and nothing has been written to EEPROM.

Here is the code:

#include "p18f4550.h"
#include "i2c.h"
#pragma config FOSC = HS
#pragma config PWRT = OFF
#pragma config BOR = OFF
#pragma config MCLRE = ON
#pragma config PBADEN = OFF
#pragma config ICPRT = OFF
#pragma config LVP = OFF
#pragma config WDT = OFF,DEBUG=OFF

unsigned char arraywr[] = {1,2,3,4,5,6,7,8,0};
unsigned char arrayrd[20];
//***************************************************
void main(void)
{
    OpenI2C(MASTER, SLEW_ON);// Initialize I²C module
    SSPADD = 10; //400 kHz Baud clock(10) @20 MHz
    while(1)
    {
        EEByteWrite(0xA0, 0x30, 0xA5);
        EEAckPolling(0xA0);
        EECurrentAddRead(0xA0);
        EEPageWrite(0xA0, 0x70, arraywr);
        EEAckPolling(0xA0);
        EESequentialRead(0xA0, 0x70, arrayrd, 20);
        EERandomRead(0xA0,0x30);
    }
}

This is the code of OpenI2C:

    /* $Id: i2c_open.c,v 1.1 2004/10/06 23:16:42 curtiss Exp $ */

    #include <p18cxxx.h>
    #include <i2c.h>

    /********************************************************************
    *   Function Name:  OpenI2C                                         *
    *   Return Value:   void                                            *
    *   Parameters:     SSP peripheral setup bytes                      *
    *   Description:    This function sets up the SSP module on a       *
    *                   PIC18CXXX device for use with a Microchip I²C   *
    *                   EEPROM device or I²C bus device.                *
    *********************************************************************/
    void OpenI2C( unsigned char sync_mode, unsigned char slew )
    {
        SSPSTAT &= 0x3F;                // Power on state
        SSPCON1 = 0x00;                 // Power on state
        SSPCON2 = 0x00;                 // Power on state
        SSPCON1 |= sync_mode;           // Select serial mode
        SSPSTAT |= slew;                // Slew rate on/off

        #if defined(__18F2455) || defined(__18F2550) || \
            defined(__18F4455) || defined(__18F4550)

            DDRBbits.RB1 = 1;           // Set SCL (PORTB,1) pin to input
            DDRBbits.RB0 = 1;           // Set SDA (PORTB,0) pin to input

        #else

            DDRCbits.RC3 = 1;           // Set SCL (PORTC,3) pin to input
            DDRCbits.RC4 = 1;           // Set SDA (PORTC,4) pin to input

        #endif

        SSPCON1 |= SSPENB;              // Enable synchronous serial port
    }


texts: Chip/board to drive low latency audio sample playback and mixing?

texts:
Generally, I wish to build an embedded system that is capable of playing back multiple high quality audio samples simultaneously, with a very low latency (eg. from trigger to audio). There may be over 4000 individual samples using 2GB of storage space and at any one time 50 of those samples may be playing. Specifically, I want to build the internals of a sample-based digital piano instrument.

What is the easiest (ie. ease of implementation) chip/board combination that could accomplish this (including the method for storing the samples)?


texts: Is there a relay to digitally check if mains is available

texts: I am working on a system that will remotely turn on/off an appliance (RaspberryPi running a web server, sending input to a relay). One problem that I still need to get sorted is that, how can I check if the electricity is available. Is there some kind of a relay (or other component) that I can use to tell my RaspberryPi that electricity is available for the appliance to be turned on/off.


texts: Thermal management of MOSFETS in TO-263 package

texts:
I'm using SUM60N02 MOSFETs in TO-263 package for my car battery charger power unit. In datasheet they have specified thermal resistance:

Junction-to-Ambient - 40 °C/W when mounted on 1" square PCB
Junction-to-Case 1.25 °C/W

I have 8 MOSFETs laid out on ~6 square inch of copper:

I will be charging a 12V lead acid battery with a maximum 20A current. Input voltage for MOSFETs will be 16V, i don't really know what battery voltage will be during bulk charge, but i guess ~14.5V.

So, I have:

\$16V - 0.4V\$ (Schottky diode, on separate board)\$ - 14.5 = 1.1V\$

\$P = 1.1V \times 20A = 22W\$ of heat dissipated.

I'm going to use a fan for cooling.

What is the best strategy for thermal management? Should just put a fan over PCB, or should i put a heatsink on top of transistors and then a fan? Or should i mount a heatsink onto a copper? I'm lost because it seems TO-263 package is optimized to transfer heat to PCB and I have no experience with serious power dissipation.


texts: Getting rid of a 3-second shutdown of 12V power

texts:
A friend of mine is wondering if it is possible to get rid of a 3-second power shortage when you start an old vehicle (press the starter). He is using the power from the 12V supply from the vehicle and he is thinking of attaching a huge capacitor for it, simply.

Is this safe?
Is there a way to calculate which capacitor to use?
Are there any other methods to achieve this?

Thanks in advance


texts: When a AM radio wave reaches the antenna does the signal need to be in a closed circuit to be amplified?

texts:
This needs some explanation. In the diagrams of radio instructions I always see a single line from the antenna to the input for amplification. Let's use a vacuum tube amplifier as for example.

There is a single wire to the plate in the triode tube from the antenna  and the electrons from the filament source are either attracted or repelled on their way to the cathode. I cannot understand how the circuit is complete since only one wire appears in the diagrams to be coming from the antenna.

Frankly I am having the same problem with trying to understand how this same tube can amplify a telephony direct current signal because I think of pulsating direct current with the voice intelligence as being a closed circuit. I wouldn't mind someone setting me straight on both.  Thank you.


texts: I am using infineon XC866-1FR controller for my project. For the motor control, I am in need of exciting the coil by the combination of two external interrupts(external interrupt 1 && external interrupt 2) at a time. Can I do a single operation using the result of AND operation of two external interrupts?


texts: Undefined behaviour in a PSRAM read memory transaction

texts:
I am reading the datasheet of a PSRAM (available here). Looking at the timing diagram for burst reads (page 10, figure 8), there is a "undefined behaviour" for a half-cycle on the DQ pins, before the data words D0, D1, D2 and D3 arrive.

What could be the cause for this undefined state of the DQ pins? Is this common for PSRAMs?


texts: Laplace Relation to Capacitors and Inductors

texts: Can anyone recommend a good resource to understand how a capacitor works as an integrator and an inductor works as differentiator? I'm looking for something to show me how the laplace transform comes into play, resulting in 1/(sC) and (sL) for impedances. Thanks!


texts: Android game reccomendation for electronics

texts:
I would like someone to reccomend me a android game regarding electronics (medium or advanced level game, no low level).
Backstory of the reason im not looking it up on my own:
I am in the hospital diagnosed with covid. They dont share their wifi here so I am on data, and cant browse all the time on the web to study nor download and test many games. I feel good enough so that I can play a game but not so good on studying a pdf/book (which I will try to do though).


texts: What does the line "edge resonance between an inductor and a capacitor" exactly mean?

texts:
I am working on a project on DC DC converters in which the concept of soft switching i.e, Zero Voltage Switching (ZVS) and Zero Current Switching (ZCS) are used. One method to attain this is using an Edge Resonant Switched Capacitor Cell (ER-SWC) as specified in one of the IEEE Transactions published in 2013: Analysis, Design, and Performance Evaluations of an Edge-Resonant Switched Capacitor Cell-Assisted Soft-Switching PWM Boost DC–DC Converter and Its Interleaved Topology.

I have been trying to find out the significance of this word edge resonance but in vain. In all my findings I could only see the lines "edge resonance between the resonant inductor and the resonant capacitor" but nothing about what it is exactly and why it is so called, knowing which would help me to justify why I should be using this concept for my converter.

.

I am familiar with normal resonance occurring in an electrical RLC circuit but not edge resonance. On googling for the same, the results are based on some communication related topics and not electrical. I have seen the same question posted before by someone else but it has never been answered. Hope this will be.


texts: How is this automotive connector supposed to work?

texts:
I want to use this crimp housing:

The problem is, when connected, there is a gap of about a centimeter between the pins and the crimps. Looking inside, there seem to be only some thin holes in plastic:

EDIT: Thanks to Andy, I found out that the red plastic is springy and can be pushed few mm. But after doing that, there is only the elastic wire that sticks out and thus, even with pliers, I cannot push the crib any further:

(A trace left by the pliers can be seen on one of the wires).) Also, the crimp does not click into place.
EDIT 2: I looked around the housing and found a slide which can be pulled out:

It allows pushing the crimps further. Putting the slide back into the housing blocks them from falling out.
However, it is not easy and one of the wires flexes so much that I cannot fully insert it. Then, this housing supports two sizes of crimps, most of the wires are going to be much thinner and I wonder how would I push them into place.
EDIT 3: I will try to tighten the crimps more, as suggested by JonRB. Maybe the wire insulation is a bit too thick for this housing.


texts: How to increase current output of an electromagnet controller?

texts:
I am modifying a Grove electromagnet controller (schematic below) to output more current with the same inputs. The controller unmodified takes in a 5V power input and a signal of 0-5V with 0-20mA. The output is 0-5V with 0-400mA. So its basically a current amplifier. What I am trying to do is redesign the controller by changing or adding components for the controller to output the same voltage with 0-1A current.

I know the desired current can be reached by changing the components and making sure they have the right power rating but I don't know which components to change and what specific components to replace them with.

The product is open source so I can modify it as needed. I know the electromagnet itself that comes with the controller can't handle that current but I am using different electromagnets for my project. Also, I know adding a transistor and an external power source is more logical to get the needed current output but I am using 32 electromagnets for my project and it's not possible to have a power source for each coil.


texts: Ground copper pour for Crystals and Real time clocks

texts:
I am laying out a (2-layer) board, with a standard SMD Crystal as well as a Real-time clock placed on the top-side of the board.

What are guidelines regarding ground copper pour under the Crystal and under the RTC, for their optimal performance? In other words, should I maintain pour-keepout areas on either side of the board, or does it not matter?


texts:
I have the following block of code -

always @(posedge clk) begin
    if (reset)
        oe_hold <= 1'b0;
    else begin
         oe_hold <= 1'b0;
         if (oe && (oe_hold | we))
             oe_hold <= 1'b1;
    end
end

In the above fragment, oe and we are driven using combinational logic. I'd expect that if oe_hold and oe are high, at clock edge 0 and oe goes low at t=1, then oe_hold would go low at t=2, since oe_hold is a register and should take on its input a cycle later.

However, in simulation, oe_hold behaves like a latch. It goes low at the same clock edge as oe. If I drive oe on the negative edge in the testbench, oe_hold goes low on the following clock edge (i.e., the same edge it went low were oe driven on the positive edge).

Can someone explain this behavior and tell me why it occurs?

Thank you.

Update 1: oe is an input to the device under test and is set like so -

@ (posedge clk) begin
    oe = 0;
end

Update 2:

Update 3: iverilog was used as the simulation tool.


texts: Soldered wires not carrying current properly

texts: I was working on a project wherein I was soldering 2 severed USB charging cables (2 wires per cable), a micro-USB to a standard USB. But when i had linked the wires together with a generous amount of solder, which did adhere to the wires quite easily, the wires did not connect or at least did not have a low enough resistance for enough current to flow. Could this be an issue with the soldering joints, or is it a problem with the wires inside the insulation having disconnected? I did get these wires from a "broken" USB charging cable which i needed to shorten, so I'm really not sure what the problem is.


texts: Dual power supply with two boost converters

texts:
I currently have a dual power supply, that supplies +/-15V. One -output of the PS is connected to the other channel's +output (GND). Now, the problem is that I need +/-50V. I bought two step-up boost converters (cheap ones from Amazon), but now I realise that I may have the wrong idea. The converters have +/- input and +/- output, and I connected the +15V from the PS into the +input of one, and -15V into the -input of the other. The unconnected inputs are grounded. Now, my idea was that one of them would give +50V (which it does), and the other -50V. Note that my +converter has its -input and -output grounded, my -converter has its +input and +output grounded.

However, the -50V is not working, and the PS keeps getting current locked. Am I connecting things wrong, or is my idea wrong?

EDIT:
Sorry for the confusing explanation. Here is a rough sketch of what I'm trying to do:

(Source)

I am using this to power a high voltage op-amp, specifically OPA454.

I'm not sure what "isolated" boost converter, but I have two of these from Amazon:

DROK Micro DC Converter Power Transformer 120W 12V/24V/48V 10-32V to 35-60V Volt Regulator Module Boost Step-up Inverter Board DIY for Car Auto Vehicle Motor

Thanks for all the help.


texts: Guitar Tube Amp RC Filter frequency fluctuation

texts:
In a simple LP or HP RC filter, is there a scenario where the centering frequency can fluctuate? So say the filter is a low pass and its set to pass everything up to 800hz, is there a situation where it may cut off at 750hz, or perhaps at a different time cut off at 825hz, etc.?

Maybe the guitarist picks the strings harder/softer, air pressure, ambient temperature, etc. could cause this? I am researching simulation techniques and trying to understand if factors like these could make an amp model a little more realistic in terms of tonal quality and dynamics.

The "Feel" of an amp plays a major role in defining the characteristics of how one plays and changing frequencies that are allowed to pass into a non-linear function will alter the feel quite drastically (at least in the digital amp sim world). The difference could be relatively small too, 120hz changed to 100hz will add a more "saturated" type feel. You may not notice much difference in tone, but you will in "feel". In the analog world I have noticed this "difference" in cut off only added to tone(allowed for more bass), but had little effect on feel.

So, can (or do) RC Filter cut off frequencies fluctuate?

Thank you..


texts: How does the coupled inductor, capacitor and diode combination work?

texts:
I was reviewing a buck regulator circuit. Circuit was designed for 3.3 V output (Vout1)

simulate this circuit – Schematic created using CircuitLab

From this buck regulator output, a coupled inductor(L1), diode  (D) capacitor (C) combination is used to generate an output Vout2. This Vout2 is used to power an LDO which will generate a 5 V output. Can anyone suggest how this L1-C-D combination works?

The chip is from TI and its data sheet can be found here: LMR23630

I am sure that it is a boosting circuit as the LDO output of Vout2 driven circuit is 5V.
But further how this is working, what is the design and what is the value of Vout2 is unknown for me.
Kindly advice.


texts: Use Paper as Shim for Circuit Board in 3V device

texts:
I've got a device (a PocketWizard Plus X for you photographers out there) powered by 2x AA batteries that needs a shim of some kind behind the circuit board in order for it to work properly.

I used paper. Is that safe? Or will it start a fire? It's touching the backs of lots of the board components.

The shim is necessary because the device has a rotary switch that changes between 10 channels, and something in the switch has play, which in turn, causes the device to work only sporadically - as if it's stuck between the channels. The shim as installed solves the problem completely and it works as new.

If not paper - is there another material you might recommend?

This will be used exclusively indoors, and it's ideal if the batteries can be left in it.


texts: Sourcing oddball stacked USB-A connector

texts:
I'm looking for an oddball stacked USB connector to repair a piece of equipment. I can't use the standard form factor, because it won't fit into the enclosure properly.

I've gone through mouser and newark and several other websites and can't seem to find anything that matches.  A verbal description: Imagine a standard 2-port stacked PCB mount USB-A connector. Now imagine that the 8 pins are inset vertically about 5mm, such that the connector is mounted into a cutout in the pcb, and dangles below the pcb a smidge.

A sloppy side-view picture:


texts: In ADS, how can I change the electrical length on a transmission line to depend on the frequency sweep?

texts: I'm setting up an S-Parameter test on a transmission line, but I want the electrical length to change and depend on the frequency. How can I go about that? The variables that I can put in are all constant-I can't figure out how to make non-constant variables. I also tried putting in a sweep plan, but I can't figure out how to use it as a variable in the transmission line.


texts: How can keep output voltage constant in pv system with MPPT (FOCV method) and buck converter?

texts:
I simulate pv array (P=213 W , Voc=36V , Isc=7.84) with MPPT (fractional open circuit voltage method + PI controller) by using buck converter , and it's work very good with power efficiency 95% with varies load. BUT voltage not constant at output !

now I need keep output voltage constant at 12 V to connect 12 V battrey . it can be connect battery direct like the load ?

and how can keep output voltage constant Ex:12V for varies load with maximum power?

Thank you :)


texts: What kind of op amp is it? how do I calculate the VA voltage?

texts:
the first value of Q1='0' (off). how can I calculate VA voltage, the  output of op amp ? I am not sure if is it like a buffer cause I've  never seen some buffer like this. thanks ahead for any help

this is what i get after i try to simulate how is possible the current flow with same voltage?? besided R1?


texts: How to charge a 4S 18650 (16.8V) battery pack with a 5V USB input source?

texts:
I'm planning on building a 4s 18650 (16.8V) lithium-ion battery pack with a 4s BMS with balance function to replace an old built-in Ni-Mh battpack.
I would like to charge the new lithium battpack via Micro USB (5V) with maximum 2A current.
My question is the following:
I can implement the USB charging by:
A) Connecting a DC-DC step up converter in-between the female USB plug and BMS. [5V source in -> DC-DC step up booster -> BMS]
B) Add a TP4056 (or something similar) connecting it directly to the 18650 cells and charging them in parallel. [5V source in -> TP4056 -> charging output to each cell separately, bypassing BMS altogether {just for charging}]
Which option is more recommended?
The problem with option "A" is that the booster module produces tons of heat even with a heat sink attached (the battpack is installed in an enclosed plastic case) or if I go with option "B" should I use single 1S BMS on each battery cell with a separate balancing board?


texts: Maintaining health of Lithium polymer battery

texts:
I have a laptop with a slightly swollen lithium-polymer battery. I know this is dangerous and I know I'm supposed to replace it. However, the replacement is half the price of a new computer, the new model will be released in a couple of months so I'm trying to wait it out. I've seen people where the case of the laptop is pushed and the trackpad breaks so I know the swelling can get worse before it explodes, if it gets to that point I'll stop using it but for now...
How do I minimize additional swelling? Removing it is not an option. I found a way to bypass the battery charging, keep it at 40%, and work directly from the power adapter. Or is it better to charge and discharge the battery and at what percentage range should I keep it?
And just out of curiosity. I've been reading a lot about lithium batteries lately. Is it better for the battery to constantly be charged and discharged or to be used less? And how much less? I read that it's actually not good to be left unused or to be left overcharged or undercharged. Is the ideal to keep it at 40% and bypass it when using the adapter? How do I extend its life to say 10 years?


texts: Type J Thermocouple Signal Conditioning to 0-5V

texts: I've been working with signal conditioning, thermocouple out specifically. I'm working with a span of 450 °C, that is, from -50 °C to 400 °C. For those values of temperatures I get, according to the table, -2.431 mV and 21.848 mV. The problem is that I need to convert that into 0-5V signal. I am thinking of using the AD620, which is an Instrumentation Amplifier. It's been impossible for me to convert -2.431mV into 0V. Do you have any suggestions about this?


texts: Difference Between - (Minus Sign) and Chassis Ground in Schematics

texts:
I was working on building some projects from the book Electronic Projects for Musicians and I noticed that in most of the schematics there are two symbols for what seems to be ground. One is a - (minus sign) inside a circle, which is connected to Vcc- pin of an Op-Amp (in addition to a + going into Vcc+). The other is the regular fork symbol for chassis ground, which is connected to the third leg of potentiometers and such. What is the difference between these, if there is any? Is it necessary to keep them separate, or are the - and the chasis ground both connected to the negative terminal of the battery?

Update: the op-amp I am using is an NE5532, in the datasheet it specifies a Vcc+ and a Vcc- (http://www.ti.com/lit/ds/symlink/ne5532.pdf)

I also included a picture of an example schematic, thank you for your answers.


texts: Importance of series resistor at output of Rectifier

texts:
For conversion of AC into pulsating DC we used Rectifiers circuits. But I read
somewhere (from a well-known site) that the circuit does not work in ideal condition if I used my first circuit. The second circuit is the correct circuit as per their view ideally in ideal condition.

As I used the first circuit many times but on breadboard only so it adds the resistance of wires so might be it works.But I do not understand the reason behind for that extra resistance actually.
Please share your knowledge regarding this. It will be a great help in clearing my concepts on this topic.


texts: Suggestions on instruments to detect pachyderms

texts: I am doing a project to detect the pachyderms in the forests when they cross the borders. Now is there is any other way other than seismic or sound waves to detect the pachyderms before they cross a border (Ruling out the camera's). I would love your valuable inputs. Thanks in advance.


texts:
I have made a relay controller module which switches a automotive relay when a ULN2003A sinks current on the separate main board. The module is in an always active state, but the requirements have changed for its functionality, it now has to handle with multiple switching cycles instead of a once off cycle. The only constraint is that it has to have three wires only: signal, GND and relay.

The circuit is this below:

simulate this circuit – Schematic created using CircuitLab

Vbatt = 12-13V from car battery

I know there are a few questions on EE.SE on the methods of flyback diodes, but I can't decide which method I should be using, I thought of using a zener, but I am unsure of that method. There is also a current reducing circuit after the NPN transistor, consisting of a resistor and capacitor in parallel Also the two answers below seem to contradict to a point.

I thus need assistance in the method in which to provide protection to the module, components within the dashed line.


texts:
I want to make sure I understand writing boolean expressions for MUXs.
For F0, I derived the following boolean expression: \$\ F0 = S1’S2’(A’B + AB’)\$
from this circuit:

Is this correct? If so, is there a way to further minimize this?


texts: Can you program a surface mount IC with flash memory and then reflow solder them?

texts:
I know that many chips, such as the ATMEGA328P-AU list flash storage lifetimes at certain temperatures, but they usually cap out at 100° C.

I know that, ideally, one should include leads on their board to program the chip after soldering, but I just want to know how the flash memory is affected at reflow temperatures of ~230° C.


texts: If the silicon wafers from which the processors are made are so sensitive that workers wear special suits how is delidding a processor possible?

texts:
I saw many videos on YouTube in which people delid processors and then apply better liquids for cooling the processor. Example: i5 & i7 Haswell & Ivy Bridge - FULL Delid Tutorial - (Vice Method)

However I also saw that people working in fabs are wearing special costumes, because the silicon wafers are extremely sensitive to all kinds of particles.

What actually happens when delidding a processor?


texts: How can I easily connect to my breadboard circuit using USB?

texts:
I'm looking to communicate with a circuit I have built on a breadboard.  I would like to communicate using USB.

Can anyone suggest an item that I can use to accomplish this?  Are their any other considerations I need to take into account?  I would rather not have just stick the USB wires individually into breadboard sockets.


texts:
I have designed a Boost PFC circuit, But upon switch on transistor is getting blown up and fuse is burnt. So I removed transistor and just connected source to ground. the circuit worked fine. Then I kept gate open and connected drain to boost inductor. The transistor again blown up.

[Edit : Schematic is added]

I am now confused because even I kept gate open and transistor being technically off. Why it is keep blowing away?


texts: How can I reduce the volume of my dryer buzzer?

texts: Like many of us, the buzzer in my dryer is loud as hell. I recently opened up my dryer to repair it and easily found the buzzer and simply disconnected it. However I got to thinking: Could I replace the buzzer with something less obnoxious...like a piezo buzzer? Most piezo buzzers I’ve seen are DC and low voltage. And the buzzer from my dryer is rated at 120V. Would there be any easy way to rig up a piezo buzzer as a replacement for the buzzer in my dryer?


texts: Using an audio splitter when using Arduino to read from an aux cable

texts:
I am currently able to feed a 3.5 mm aux cable into my Arduino and read its values, but I'm not able to hear the sounds being played. I wanted to solve this problem by using an audio splitter and adding speakers. However, when I read values from my 3.5 mm aux cable attached to the audio splitter, I'm only getting 0s. How can I fix this problem?

Edit: Without the audio splitter (Arduino can read values from aux cable):

With the audio splitter (Arduino can't read values from aux cable):

The source of the audio is from my laptop and it is a stereo signal. The splitter is also has a stereo signal. The Arduino is reading the signal in the A0 port and its being powered from my laptop.


texts: Simulated bode plot in Simplis is different from the result of Mathcad

texts:
I built an open-loop-controlled buck converter in Simplis.
The parameters are listed below:
\$V_g=12V,V_{out}=5V\$
\$D=0.52\$
\$C=100\mu F,ESR=5m\Omega; L=30\mu H,ESR=5m\Omega\$
I use Simplis to simulate the bode plot of \$G_{v_d}\$. And I use the Mathcad to simulate the same circuit. But the result was different. During the low frequency, the peak gain margin in Simplis is less than 0db, while in the Mathcad, the gain was about 20DB.
Here are the results I got.
the circuit in Simplis

the Gain bode plot in Simplis

the code in Mathcad

the curve in Mathcad

I don't know what kind of mistake leads to this result. If someone knows the reason, would you please tell me? I am a freshman in Power electric and I appreciate your guidance .


texts:
The datasheet for the IR2110 shows this diagram:

Where vss is the digital ground. Does this mean that the block Vdd/Vcc LEVEL shift provides some kind of electrical isolation? Or it's the digital side of the chip still connected  to the power side?


texts: When can I neglect the voltage drop of diodes in a circuit?

texts:
Let's suppose a Rectifier with Vd,on=0.7 V is connected to a sin-voltage source with Vamp=10 V. When in this case of forward bias can I ignore the voltage drop of the diode? Or is it only possible if the input voltage has a very high amplitude? I've heard that you can do in for example 5000 V, is it right and why is that?
In this case I haven't ignored the voltage drop and the output voltage is Vpeak-2Vd,on.


texts: Tried connecting 2 things two 1 battery, smoke ensured

texts:
I'm assembling a quadcopter and have run into a problem

So, I have one two cell LiPo battery if I've understood things right, it outputs about 7.4V and has one ampere hour.

Now, I have one radio receiver and one flight controller (It's basically the motors + a circuit that stabilizes the copter). If I connect the battery to the receiver it it works, If I understand my multimeter right, the receiver used 7.5V.

IF I connect the battery directly to the flight controller it also works and also seems to use 7.5 Volts.

Now, If I've understood things right, if I were to connect all there 3 in a series, the receiver and the flight controller would each get half of the voltage, which I guess is not enough(?).

So what I did was to connect them in parallel which, if I've understood this would mean they would both get 7.5V.

However, when I connected everything I started seeing smoke from the flight controller and removed the battery ASAP.

So now on to my question, Have I made some serious error in my reasoning or is it more likely that I made some error in my actual uhm. connecting stuff?

I've triple checked that I didn't mix up positive and negative anywhere

EDIT: ok, so I did some troubleshooting and I found out that most receivers have the same output voltage as they have input voltage, so my receiver would output 7.5V (which I tested). And normally receivers should operate at 5V or so. which means that the flight controller receives more voltage than it should.
I'll now try to connect an UBEC before the receiver to reduce the voltage

Second edit: so I tried with the UBEC and then it seems like the flight controller didn't get enough power, the LED display lost it's backlight illumination, so I hokked up a seprate battery to the UBEC so the flight controller and receiver have different batteries and then I fried the flight controller. I'll buy a new one and do some schematic-drawing next time, thanks for the help everyone


texts:
I'm looking to repair some electronic equipment and am scratching my head why the part I need is so hard to identify.

I recently had a bad connector on an Aputure Tri-8s LED light (Brand new out of the box) but had little intent to USE the battery terminals regularly and needed the light for a project. The connector was loose;  any shock to the battery would cause it to disconnect and infrequently minor arching could be heard. (I initially suspected a bad solder joint or something;  but this was not the case)

I don't personally like using warranty to "fix" such a trivial problem, the shipping cost alone would have been orders of magnitude more then the actual part or repair work, so I emailed the manufacturer and asked if they knew of a source of spare parts. (that was a few days ago;  I have not heard back yet)

In the meantime;  I (likely voided my warranty and) disassembled the product and found that the fault was simply a collapsed spring inside one of the battery terminals. (I actually managed to fix the existing connector by disassembling it, stretching the spring back out, and re-assembling the connector)

At first I assumed that the top pin would be retained using a rolled lip on the brass body; but these specific units are actually just press-fit and I was able to simply pull them apart and press them back together.

POINT BEING;
Sony NP-F style batteries;  appear to use a ~3mm (might be 2.97mm) spring-loaded pin contact.  I have not been able to locate a source for these contacts;  nor have I been able to find a model of the pins.

I assumed that given the common nature of these in the photo/video world;  many people would have experimented with building things that USED such batteries and I'd love to make a few adapter designs on a 3d printer:  but I am unable to determine the model / source of such pins.

Here's what they look like:

I don't have exact dimensions but if anyone knows what terms I should be looking for,  I'd be happy to figure out the exact part from a supplier catalog.

The connectors are approximately 3mm in diameter;  and AROUND 12mm from the tip of the healthy pin to the end of the solder joint;  but I did not accurately measure these dimensions)

I'd love any literature on the NP-F battery integration;  if any such information exists.  I tried searching around online unsuccessfully.

I'm aware that this is not an EE question specifically;  but DIY electronics and product design didn't seem to have a better section.


texts:
I need help in creating a layout or circuit for this state machine and instructions on how to put the hardware together.
It’s a rotary encoder that’s application will be into a gaming controller.. scrolling up will spam a certain button and scrolling down will spam another. The hardware components I currently have are 2 Microcontrollers SN74HC74N and SN74HC00N, 4 resistors and 2 capacitors along with breadboard and cheap mouse for encoder and scroll wheel housing to modify into controller. I can supply data sheets for the 74s but I’ve not clue which pins to solder to what. This diagram has been given to me as a start I believe.The bit generator is the 3 terminal encoder.


texts: Did I correctly use the Voltage divider rule to derive the transfer function?

texts:
Question and diagram are on link and NOTICE Rs is assumed to be a short.

I believe the transfer function is going to be:

A(jw) = 1/(jw*C1*R3+1)

I arrived at this answer by using a simple voltage divider rule considering Vi to be the source voltage to the impedance of C1 and R3; the voltage across R1 is exactly the same as the input voltage Vi since it is given that Rs is a short.

Am I right by believing that the current across C1 and R3 is the same as the current across R1?


texts: Replacing a diode-OR gate by a circuit that behaves the same way (also in the presence of feedback loops) without accumulating voltage loss

texts:
Consider the following circuit with two OR gates:

simulate this circuit – Schematic created using CircuitLab

and the Time Simulation:

The OR gates with both inputs 0 generate 0, and after one input is set to 1,
they remain with 1 as long as there is current. The circuit has memory.

Now consider the implementation of OR with diodes (let's call them diode-ORs):

simulate this circuit

and the Time Simulation:

In this case, the diode-ORs always generate a 0 whenever both inputs are 0.
The circuit has no memory.
And there is a loss of voltage, that would accumulate if more diode-OR gates were cascaded.

My question is the following: is there another implementation that behaves like diode-ORs
(i.e., without memory even in the presence of feedback loops)
but does not have a cumulative voltage loss (or has only a very small voltage loss)?

Or put another way: can we replace each of the two diode-ORs by a circuit so that the whole system behaves the same way, except that there is no cumulative voltage loss (or the voltage loss is very small)?

Maybe using pass transistor logic? (https://www.electronics-tutorial.net/Digital-CMOS-Design/Pass-Transistor-Logic/OR-gate-using-pass-transistor-logic/)

Dave Tweed suggested to use a "better diode" and that is a correct answer to the question. Is there any other alternative? A problem with that solution is that it cannot be used for the AND case, which I would also like to handle in that way (with low voltage drop, and without memory even in the presence of fededback loops) because diode-ANDs have memory when there is positive feedback (https://en.wikipedia.org/wiki/Diode_logic#/media/File:Diode_AND2_Ideal_Diode.jpg).

I am a computer scientist and I am interested in the answer mainly for theoretical reasons and for teaching purposes.
I know that the feedback loop is not needed to generate the outputs of the circuit.

Thank you!


texts: Which components can be measured while soldered on a PCB board already?

texts:
I am assembling nonlinear oscillators on PCB boards for applied math research [Colpitts (100 kHz, 3 V_pp), FitzHugh-Nagumo (100 kHz, 15 V_pp)]. I am working with some other people that want to do ODE simulations, so I am pushing to provide some qualitative results quickly. This means I sometimes solder up components before I rigorously measure them, because an approximate measure (~100 ohm vs 99.24 ohm) is enough for the data I need to hand off.

Can I measure these components (resistance, inductance, capacitance) once they are soldered in, or do the connections negate this possibility? Sorry if this may be a basic question, but my background is not in electronics. I understand that I can remove them, measure them, and then re-solder them, and this is probably the obvious approach--I would prefer to avoid doing this because small qualitative changes in the behaviors are important to me, and re-soldering would probably cause that. Should I just take the time/repeatability hit and always measure isolated components?

Also, do any of you have an intuition on what magnitude of stray capacitance occurs on a PCB board? I know that software layouts like PSpice avoid these problems, but I don't know how to use that functionality yet--if I'm being pessimistic, would I see 10 pF? 100 pF?

Edit: I include a picture of one of the soldered circuits so you can get an idea of spacing and the complexity of the circuit (not pictured--the leads for the V+/- power sources for the op-amp).

Edit 2: I include a schematic of the pictured circuit, so I can ask where I might consider that suggested capacitor.


texts:
Capacitor are said to be linear but not static.

After reading for a while, through complex explanation, from what I understand is that like a resistance it is linear, but it's linearity may change. If I'm correct, it's linearity would change with the frequency?

Is there anything else than the frequence which can change de linearity or only the frequency?


texts: I made a truth table for this sequential circuit, and I wanted to make sure that it is correct.  Is this right?  The top left is a full adder, and the top right is a D flip-flop.


texts:
simulate this circuit – Schematic created using CircuitLab

In this circuit how is it possible that Vout is ten times greater then Vin? Vout's measure is made by an oscilloscope 1M ohm internal resistance.


texts:
This is probably an absolute newbie question but what happens to "unchanged" output register as in the following example(pseudocode):
module TOP(
   input CLK,
   input A,
   input B,
   output reg O1,
   output reg O2
);

reg state = 0;

always @(posedge CLK) begin
   case(state)
      0: begin
          O1 <= A;
          state <= 1;
      end
      1: begin
          O2 <= B;
          state <= 0;
      end
   endcase
endmodule

Do O1 and O2 keep the same value as for the last pass where they were specifically set or are they undefined in the pass where they are not specifically set?
Thank you very much in advance!


texts:
I've bought a Texas Instruments CC2650STK SensorTag dev kit to experiment with. It says on the website that I can activate ZigBee by pressing the button for 3 seconds. It doesn't seem to do anything as far as I can tell.

Does anyone have any experience of getting ZigBee working on these devices?


texts:
When i am working my Altium project files (schematic and pcb), i realized that they are stored in "History" folder for everytime i click "Save" button. Size of "History" was gigabytes. Do you know a way that can prevent this situation?

These are my Local History and Backup preferences;


texts: AC to DC converter device (AC adapter) with adjustable output voltage and adjustable output current

texts:
Is there a device available in the market that can take an input AC from mains and convert it into DC and output it, the output current and voltage must be adjustable.
I know there are AC adapters with adjustable output voltage but no adjustable output current. I'm looking for an AC adapter that allows me adjust both the output voltage and the output current and not just the output voltage.


texts: Can I make an ultrasonic motion sensor using one piezotransducer?

texts:
I wonder whether I can make a small motion sensor using one piezotransducer with a feedback.

It should emit a low-frequency ultrasound (say 33kHz) and I expect to see some signal changes on a feedback pin when something moves nearby.

Does this sound real?


texts: Subtracting two voltages using an op-amp

texts:
I'm essentially a digital guy, and am used to using a comparator to compare two voltages and give a high or low depending on their relative values.

Now instead I want to subtract one voltage from another, and have the difference be available as an output.

I breadboarded the following circuit, but it doesn't seem to work right:

I am using two op-amps as voltage-followers, and feeding them into the inverting and non-inverting inputs of another amp-amp.  The quad op-amp chip (LM324) has a single supply (9v).

EDIT: see my comment to the accepted answer -- I was on the right track, but had a bent pin on one of the output pins.

Now, since I do not have a negative supply, so the output cannot go negative, what I really want is for the output to be biased by +2.5 volts, so that if both pots are set midway the output will be 2.5v, not zero.  Instead of adding the resistor from pin 12 to ground, I tried putting a 4.7K resistor from the non-inverting input (pin 12) to a 2.5v reference, and that seems to add in the offset I wanted.

So it now appears to do what I want.


texts:
In this MIDI-audio Patch circuit the capacitor has several lines though it - the lines look like ground lines - what do they represent ?

Does one connect the up and down triangles to each other, or are they separate (i.e. keep up triangles separate from down triangles ). I am assuming they are signal ground
Thank you


texts: What is the use of civil drawing for an electrical engineer?

texts:
I'm reading for a BSc in electrical engineering. In this subject, I've found a subject named civil drawing.

Why do electrical engineers need to understand civil drawings?


texts: How and where to add a dc blocking capacitor for a gps loop antenna?

texts:
I have a SoM (Snapdragon 820) on a development board .
I want to test a loop gps antenna(Antenova-Bentoni-SRFG017-MHF4).
I need to add a blocking capacitor to be able to make it work.Where /how can i add the capacitor?

A little more information :

I am working with a development board(Dragonboard 820) which is designed to work with active gps antennas.
I want to test a passive (also a loop) GPS Antenna.
According to support departmant of board manufacturer , it is possible , but only with a dc blocking capacitor.

Since I do not design the circuit board , i am not able to add anything to it.
Should i make a bridge-like connection pcb which have connectors and capacitor on it ?
Or what is right/best/known way to achieve that ?

Thanks in advance!


texts: Revive a dead LED Lantern Sealed Lead Acid Battery

texts:
I recently found my lost LED Lantern after one year in my old garage, but unfortunately it wasn't worked when I turned on.

I opened it and checked if the charging circuit was fault, but it wasn't because I tested charger circuit with another small sized rechargeable battery(I didn't know if it is lead acid or another) and battery had charged fine.

Then I though battery was fault and I was right, this 4.0V 2.0Ah rechargeable sealed lead acid battery even not charged with a power pack(I tried adjusting voltage from 3V to 6V even 12V, even not charged).

Its voltage remained 0V when I tested with my multi meter.

The Lantern is Rikon and Battery is a RB420C model, bigger than the good small battery I tested.

I can't think why this small torch battery which even not used for more than one year charged fine, but this wasn't.

Any help is needed me to determine what to do, replace bigger battery with my unsuitable small battery(because both batteries are very different) for the lantern or any step to take this dead battery back to life?

Worked Rechargeable Battery:

Dead Sealed Lead Acid Battery:

Thanks in Advance.


texts: Zener Diodes with low forward voltage drop

texts:
I've designed a number of boards which utilise different kinds of diodes, and thought I had a good handle on how they work and their properties - however recently on doing some reverse engineering work i've found some diodes with properties that have somewhat confused me.
On probing boards with a DMM in diode mode, I would expect forward-based diodes to display a voltage drop ranging from 0.5ish to 0.8ish Volts - but on two boards this week i've found diodes measuring around 0.1V.
It could be that these diodes are faulty, however the boards are in as-new working condition so I suspect what's really going on here is that there is some scenario where if a diode is used in a certain way within a circuit, it gives low readings when measured in situ.

On the most recent of the two boards (above) there are 5 identical Zener diodes (ZPY24 - I believe), all of those circled blue have a 0.5V to 0.7V forward voltage measurement, the pink has a forward voltage of 0.1V (I know it's physically reversed - I measured with correct polarity).
My question is, how would you have to place a diode within a circuit for it to measure this way? Surely if my meter leads are passing a small voltage out of one probe, through the diode, and back into the other probe, the diodes position within the circuit shouldn't affect the reading?
Thanks in advance!


texts:
I am new to electrical engineering so I am not even sure that I approach this problem correctly, so I will first give some background information.

I have a RC car (LEGO dirt crusher 8369) that I want to control from a raspberry pi. In order to do that I disassembled the car's remote controller and found out that if you connect the green cable and the black cable the car starts to move forward. If you connect the black cable and the other cable the cars starts to move backward. This lead me to think that I can use a transistor as a switch that will either connect the two cables or disconnect them, depending on if I turn on or off a GPIO pin connected to the base on the transistor.

The problem is that this does not work. Regardless of what I set the GPIO pin to (on or off) the car still moves forward, which means that current is flowing through the cables and the transistor.

Here is an image of the remote controller:

The current is flowing from the green cable through the black cable. The current is 23~27 μA. The voltage between the cables and GND is 30 mV.

Below is an image of the remote controller connect to my raspberry pi via a transistor.

The transistor I use is a "C546B" transistor. The black cable is connected to the emitter and the green cable is connected to the collector. To the base I have connected a 4.66 K resistor and then a brown cable that goes to a GPIO pin on the raspberry pi.

I have tested with a multimeter that the GPIO pin work. When the GPIO pin is turned on it output 3.3 V and 0.678 mA as expected. When I turn it off, it outputs 0 mV and 0 μA.

If I remove the brown cable so nothing is connected to the base, the car stops moving forward as expected.

One interesting thing to note is that the car "lag" a bit when I have the transistor in the circuit. The car starts to move forward, then stops for around 100 ms and then starts to move forward, stops for a few milliseconds, and so on. If I connect the green and black cable directly to each other the car move forward uninterruptedly without any "lag".

I also have tested to swap the emitter and the collector cable but that makes no difference.

Why is the transistor always "on" regardless of setting the GPIO pin to on or off? Do I need some special transistor, if so, how do I know what to look for?

-

TL;DR:

Current is flowing through the transistor even though the GPIO pin is off. Why?

simulate this circuit – Schematic created using CircuitLab


texts: Is there a logic gate which directly outputs (A'B)' (complement of, A complement product B)?

texts:
I know I can do this with two separate NAND gates, but it would be more space consuming. Is there a single standard logic gate (e.g.; 74V1Gxxx - SOT-23 package is preferred) which produces this result?

Or, can I get this result by using two transistors at most?


texts: how does this op amp circuit 0-10V converter work?

texts:
This circuit is supposed to be 0-5V to 0-10V/4-20mA converter.
I know that :

R7+C1 forme an RC filter
R5+T2+R4 an inverter to switch between 0-10V and 4-20mA in output
the Op-Amp is working as follower

I tried to simulate it in Tina-TI BUT I didn't get anything in the output.
My question : What does T4 and T1 do? and HOW exactly the circuit works to provide the 0-10V/4-20mA?


texts:
Hi I'm looking for a component that does the following: if the voltage is below 1.5 V, then you need to make it 0 V. I'm looking for a high pass filter but with a certain voltage value. Does this exist?

Yes, I want to keep everything above 1.5 as is, everything below 1.5 V to be 0. I'm working with the power pin on a USB connection. I want to cut off all power coming from the USB. Currently, I'm issuing a command in the terminal which changes the USB power to 1.5 V through a USB hub, but I need that 1.5 V to go to 0 V.


texts: I need a (preferably analog) circuit to monitor a solar cell trickle-charged capacitor and automatically discharge the capacitor when it's charged. The idea is to use solar cells to power small solenoids or motors for remote outdoor devices, intermittent and random discharges are fine. I plan on trying several sizes of solar cells and capacitors to see what works best in various applications. If you know of a good reference, I should look at, that would be great.


texts: Two alternating slow fading/flashing LED's

texts:
I found the perfect circuit for a flashing pattern, only I need two LED's to alternate with this pattern.  I attached the flashing circuit found on YouTube, copyright of GeoProgrammer. So basically, first LED would flash, then the second then the first again and so on. Making it possible to regulate the switching rate would be great. It is for a scale model. All help very much appreciated in advance.
I hope I can express better what I mean by showing two GIF's. First shows two LED's alternating. Simply on off. The second GIF shows how I would like each LED to light up, instead of just turn on and off.
i2-download.imgflip.com/4rc8d7.gif
i2-download.imgflip.com/4rc6lt.gif

simulate this circuit – Schematic created using CircuitLab


texts:
I understand (or am learning, rather) how both RS232 and USB work. What I am really curious about, and can not seem to find much information for, is what kind of disadvantages do USB to RS232 dongles have, if any? I understand driver issues and all of that, I mean is there any significant functionality of RS232 that is lost in the conversion, or can USB to RS232 conversions behave exactly like a native RS232 port?

Additionally, if some dongles are better than others (now with respect to both possible functionality and decent drivers, preferably linux based), do you have any suggestions for a good brand or model?


texts:
Here's part I!

They helped me a lot. But this problem is harder so if you can tell me where, if, I went wrong.

When first switch is closed, the other one's opened. And in reverse.

Here's solution one.

Here's solution two.

P.S. Series come before parallel, right?


texts: How to trigger power bank to output 12V?

texts:
I have a  power bank that can output 5V fast charge or, 5V 9V or 12V regular charge.

https://www.banggood.com/JUWEI-QC2_03_0-Automatic-USB-Tester-Voltage-Ammeter-Quick-Charger-Power-Bank-Voltage-Trigger-p-1193891.html?gmcCountry=US&currency=USD&createTmp=1&utm_source=googleshopping&utm_medium=cpc_elc&utm_content=frank&utm_campaign=pla-elc2-rm-mail-us-pc-0801&gclid=Cj0KCQiA7briBRD7ARIsABhX8aB96Xvey2jcVyxomApEos681neoBoqblU7PtxHJ7P-89D2S6meBIr4aApFfEALw_wcB&cur_warehouse=CN
I am using this voltage trigger to get the 12V output desired but I have a special condition.

The power bank will be secured away and I will not be able to access the buttons to change it to the mode needed.
I soldered a wire to the positive and negative side  of the "up" button on the voltage trigger. I did the same for the "mode" button as well.

I wrote a small program that reads the Voltage output of the power bank using a voltage divider to have the ~12V match the top voltage that the arduino can read. When the power is not at the right setting it sends a signal to an N-channel MOSFET to simulate the button being clicked and change the voltage level.

When I touch the positive and negative wires that I soldered to the "up" button for about 700ms the voltage  output changes. I've tried a HIGH pulse and a LOW pulse at different lengths between 700 -1500 ms with the N-channel MOSFET that doesn't quite work.

The problem is that sometimes the voltage trigger toggles between the power levels without any influence. Even when all wires are disconnected and its just the power bank and the trigger. That makes it difficult/impossible for me to be sure  that my program is running correctly, or that I can rely on it to set the output to 12V

What options do I have to get  the power bank to output 12V without needing to manually do anything?


texts:
When I want to model a electric motor as a plant, the transfer function is:
$$
G(s) = \frac{1}{Ls + R}
$$
And this can be used, to automatically set the optimal current control gains of a PMSM motor. Let's say I have a star connection of the motor and I measure the resistance/inductance along two phases, do I need now to use the measured resistance/inductance, divided by two or do I need to use the measure inductance, that would be seen by the controller when applying voltage to a phase?


texts:
Does any one know if it is o.k to run a soldering iron over the connector with the fine black traces on in the photograph attached(or below I am new to pic posting :D)?

I have an office kitted out with Siemens optipoint handsets (410's and 500's for those interested) and they are having the missing lines issues, much like the original Gameboy does with it's LCD, which is apparently common with these handsets.

I would like to try and repair them but don't know if I can apply enough heat to do the job with out blitzing the connector. Anyone experiences with these type of connectors would be appreciated.


texts: What does yellow border around component in KiCad Pcbnew mean?

texts:
I'm working on a PCB layout in KiCad Pbcnew.

I notice there is one and only one component that has a yellow border, R16/10K in the screen shot below.

What does that indicate? It doesn't seem to correlate with the most recently clicked element or anything like that.


texts:
I am making a simple robot, and am using a relatively cheap RF transmitter and receiver to send commands to my robot. Essentially, the transmitter end would send data from an AVR MCU via its UART to the RF transmitter, and a similar setup on the robot would pick up the data.

So what I am confused about is how this whole process works. I mean, suppose I have four motors on my robot which all need to be controlled individually and at the same time. How would I accomplish this? Would I encode my info in a byte (say, 1111000) where the first four bits represent the on or off position of the four motors, and the receiver would decode this and carry out the necessary task? Or is there another, better way of doing this?

This leads to my next question related to this. Suppose the method I just described is used, then how is the robot typically programmed to handle commands? Say, it receives the 11110000 packet, and turns on all four motors. Do I just let the robot keep the motors on until a new packet of info is received? Essentially, if I want continuous communication with my robot (one way is fine in this case), how would I do it if it takes a certain amount of time between each signal which is sent to be processed and carried out before the next one comes in? Maybe the time it takes for the signal to be sent, processed, and carried out is is small that the impact is unnoticeable?

EDIT: Here is a link to the RF Tx/Rx I bought.


texts: how can a GPIO of stm32 have many alternative functions?

texts:
I am working on the assignments of pins of STM32F103ZET1.

On page 31 of datasheet, it says that PA0 has many alternative functions: TIM2_CH1_ETR \ USART2_CTS \ WKUP \ ADC123_IN0 \ TIM5_CH1 \ TIM8_ETR. From the reference manual, I know that TIM2_CH1_ETR and USART2_CTS can be remapped.

What about other functions? What if I want to use TIM5_CH1 and TIM8_ETR at the same time? How can the STM32 know whether I want to consider PA0 as TIM5_CH1 or TIM8_ETR?

1: datasheet, reference manual


texts: Power dissipation calculation for FPGA-ADC interface

texts:
An FPGA can be interfaced with an ADC using CMOS or LVDS. Is there a way to use simulation to predict the power dissipation of the I/O blocks for a given operating frequency for this interface? If so, how can this be carried out?
Here we have an Intel MAX 10 and a Microsemi IGLOO2 being linked to a TI ADC. It would be great to be able to get a very reliable estimate for power dissipation between these two FPGAs when using LVDS and also when using CMOS, to interface with the TI ADC.
I am sure more information will be required to reach a complete answer.


texts: Given 4 inputs (A,B,C,D) how can I design a circuit that counts the number of 1s?

texts:
The question is in the title.
If I have 4 inputs, how can I count the number of 1s using full/half adders and produce the binary equivalent of how many 1s exist in the 4 inputs?


texts: Bypass a linear voltage regulator by applying a voltage at the output while input is not connected?

texts:
Question

Is it safe to "bypass" (as in circumvent) a linear voltage regulator by applying a voltage to its output (equal to the specified regulator output voltage), while the regulator input remains unconnected?

Details

I have a circuit which is powered by a 6V adapter (a "wall-wart"). The 6V adapter supplies the input of an ADP3338 (through a diode), which delivers 5V regulated output to the rest of the circuit.

Now I am interested to see how the circuit would respond to a different 5V supply. That is, I would like to power the circuit from an external 5V supply, bypassing the ADP3338 (without otherwise tampering with the circuit).

My idea was to simply connect an external 5V supply to the output of the ADP3338, while leaving the input (6V from adapter) unconnected. This is illustrated below:

However, I am not sure if this is safe, or if it will destroy the regulator, or if it will mess with the rest of my circuit in some other way.

The functional block diagram from the ADP3338 specs, depicted below, shows a resistive voltage divider between GND and OUT. I measured 0.7M Ohms between these two pins, so I guess that should not be an issue. But how will the rest of the regulator circuitry react?

Thanks for your help.


texts: I'm looking for source which simply described how can choose right power supply, for example it possible to use one power supply with same voltage and higher amperage insted using sevseral power supply with lower amperage? If it is not possible explain for what and if its possible under which conditions it is possible


texts: Looking for a display RAM for my VGA card

texts:
I´m designing a simple 800x600 pixel VGA card, based on this example (but I don´t reduce the image size). I also want to use a display RAM, so a microprocessor can write a new image. For this I need to look for a two port display RAM (or?), so the VGA controller can read the image while the processor is writing the image data - I want to use this video card for some kind of retro PC later.

Does this thought sounds like a good idea? Or is does a better solution exist?
And finally I´m looking for a good (cheap) SRAM which can be used as video RAM (dual port if this idea isn´t the wrong way).


texts: Using a 5V Optical Mouse USB Cable to Power a toy requiring 4 Size D batteries

texts:
I have a baby swing which requires 4 Size D batteries to get power. Here's a picture of such a thing - a human baby goes inside.

Googling the information on Size D batteries, I found that 4 Size D batteries equals

1.5 V * 4 = 6V

I want to power this toy using an old optical mouse USB cable.

The specification on the mouse says 5V and 100mA.

Questions:

1) Can I use this cable to power my toy ?

2) Is this correct: Red Wire in the mouse cable connects to Positive Node of the toy and Black Wire in the mouse cable connects to Negative Node of the toy ?

Thanks for reading!


texts: How do I measure the analogue in voltage of a ICL7136 using an Arduino

texts: I have ICL7136 MQFC (the square one) chip driving an LCD display. it's measuring and displaying temperature data from a thermometer probe. I want to grab the analogue readings an log them with an Arduino as well. How what type of setup would yield something usable. Would I just measure from the IN HI or IN LO to the analogue in of the Arduino?


texts: Is this a good way to debounce a switch?

texts:
There are plenty of debouncing circuits on the internet, but I couldn't really find one that fitted my needs / available parts, so I came up with my own, from what I had. There's nothing special about it, and it probably already exists, I just haven't come across it yet.
Here's the schematic:
schematic http://kepfeltoltes.hu/141017/debouncing_www.kepfeltoltes.hu_.png
I guess it works with 5V as well, but I use this with my Raspberry Pi, which has 3.3V logic on the GPIO pins, that's why it says that on the schematic.
I went with the 330k and 100nF combo because I read that some switches can even have a 10+ ms bounce, so I really wanted to make sure this thing smoothes out everything. I don't need super fast switching, so this is fine for me. It makes both rising and falling edges very smooth. Also, it kind of inverts the switch: when it's open, the output reads high, and when you close it, it drops to 0V. But I'm good with that.
So I just wanted to know whether this is any good, or should I take a different approach? What do you think of it? Any advice maybe?
EDIT:
I updated the circuit a bit based on your suggestions. I realized that the 220 ohm resistors were wasting current for nothing, so I replaced them with more appropriate values. Also, I went with 100k / 150nF for faster operation. I think that the 330k / 100nF was a bit of an overkill. As you can see, that would reach 1.8V (roughly the logic threshold for the Raspberry Pi GPIOs) in about 25ms. This new circuit takes about 10ms to reach that level, therefore allowing over 10ms of bouncing, which is enough for almost all switches, and still unnoticeable for a human.
Also, I know that I the transistor is redundant, but I already built it this way, so I'm leaving it in there.
schematic 2 http://kepfeltoltes.hu/141018/debouncing_v2_www.kepfeltoltes.hu_.png


texts: Is there a mistake in this microcontroller schematic?

texts:
I was looking at the eagle schematic for a project and something caught my eye. Take a look at reset button on this schematic (From https://www.arduino.cc/en/uploads/Main/Arduino-Pro-Mini-schematic.pdf):

Why is there the VCC right in front of the Atmega328P? Doesn't this indicate that there will be a shortcircuit (VCC - GND) whenever the reset button is pressed?

What makes more sense to me the same line connected to VCC via R2. This way power is dissipated through the resistor whenever the reset button is pressed. By why the other VCC?


texts: How do you design a circuit to implement the Bipolar Line coding Technique?

texts:
Bipolar NRZ
http://www.tutorialspoint.com/data_communication_computer_network/images/bipolar.jpg

In this technique alternate 1's will have alternate polarities and 0's will be zero itself.


texts: Finding voltages in a circuit with current source

texts:
I am trying to understand the basics of current source, but I don't know how to calculate the voltages v1 and v2. I tried to sketch the expression for current divider, but I think I didn't actually understood how to use it properly on an exercise.

simulate this circuit – Schematic created using CircuitLab


texts: Beginner: How to wire up a navigation button / joystick?

texts:
I have a joystick that I wish to connect to my Arduino uno. However, there's no VCC or 5V or GND pins to connect to. I do see a COM pin, but I'm unsure how I should wire that to the Arduino. My objective is to take an input that determines whether LEDs should be emitting light or not.

I can't find any model number on the PCB or on the listing where I bought it from. The only information provided on the listing:


texts:
People say that dielectric should be an insulator so that it can decrease  net electric field increasing capacitance..

My question is if the object is a insulator how does the object get polarized and how does it get a electric field inside? How do you know that electrical field applied by the dielectric is always lesser than the ones made by the parallel plates of the capacitor?


texts: As I was reading basic electronics, PN-junction diodes and two terminal MOSFETs, I understood the position of the fermi energy level and position of valence and conduction band in those devices. But I would like an explanation on how the bending of the valence or conduction bands occurs with the application of proper forward bias for either an N- or P-type PN-junction diode or a two-terminal MOSFET.


texts: How to split voltage from a DC power supply?

texts: Given a 12V 4A DC power supply that's connected from a wall outlet to a V59 Universal LCD Controller, can the voltage be split from this power supply to power another device with 5V 1200mA power requirements?  If so, how exactly should the wiring be connected and what other components such as resistors might be needed?


texts:
I had a question about the resolution of an OLED display. It's says the resolution is 128x128 dots under the display format in the datasheet sheet of the OLED. Does this mean that there are 128 dots per inch horizontally and also 128 per inch vertically on the display ?
How does this convert to pixels and pixels per inch ?


texts: I have seen some internet electronic forums claming that low quality cool white LEDs emit more UV light than CFLs. Is there any truth in this claim?


texts:
I'm trying to find a way to connect a temperature and humidity sensor DHT22 to an XBee's RX/TX pins without an additional microcontroller(Arduino or anything that needs software) or reprogramming the XBee

Disclaimer: I do software by day, noob in electronics.

I started out this wireless sensor project thinking it would be easy to skip the microcontroller but I'm now thinking it would be hard to do that without creating an unreasonably big board.

Yes, I already know that I can do it with Arduino/PIC etc. I already know I can do that with some crazy set of timers, shift registers etc.

What I'm looking for is a hack that uses the minimum number of elements.

To direct your thinking this I what I tried: I tied the Data of DHT22 to RX of the XBee to the through a diode and to TX straight up, the idea being the RX wouldn't be bothered when the DHT is transmitting. Then I set the serial settings to 115Kbit/s, hoping that I could use use this as a 1-bit oscilloscope: instead of the 40 bits that DHT transmits I'd get 4800 bits on the other end, roughly scanning the level of the DHT Data:

0000001110000001111111111000000.....

... and I would trigger the DHT by sending 11111100 or some other sequence that has 6 '1's.

I couldn't get this setup to work so I'm curious if there's a way to make it work. Any other approach I can use? Again: I'm looking only for a reliable, simple and easy to execute solutions.


texts:
I'm working on a fairly dense PCB at the moment and I'm having trouble fitting in all the component labels.

What is the minimum readable standard size for component designators on the silkscreen?

For example: What should the width and height be here?


texts: How can I actuate a relay coil from a headphone jack's internal SPDT?

texts:
I want to plug my iPod which in turn supplies power to an external audio amp while sending iPod audio signal to same amp.

Is it possible to wire an 1/8" (3.5mm, mini) stereo jack in such a way that when the connector is inserted, a relay coil is actuated that powers on a car audio power amp?  I have a 12V DC relay but how can I use the jack's internal switch to actuate the coil when the headphone jack's switch is essentially backward?

This is for a boat.  The only solution I can come up with is to have the relay coil normally actuated but I think this would eventually drain the battery (I haven't done the math on that).

I have this Radio Shack version headphone jack with the internal SPDT but the switches are not isolated from the audio signal and are N.C.:
http://www.radioshack.com/product/index.jsp?productId=2103451  Surely designed this way so that the audio signal is passed to the big-speaker-amp when the headphones are disconnected.

(this is where the images were to my minijack diagram and my relay diagram...oh well...I'm a new user and this is clearly spam...)


texts: Is it safe to disassemble an unpowered PC power supply?

texts:
Once a typical PC power is unplugged, is there any danger of receiving a shock while disassembling it?  Are there typically high voltages stored that one should be aware of?

context: removing a cooling fan from an obsolete but functional power supply before recycling.

  Safety note to readers:  this is a very general question, and the
  answers will indicate general guidelines about typical power supplies.
  Observe caution and refrain from performing any activity (such as
  touching wires or components with your bare hand) that you have not
  confirmed as being safe in your circumstance.


texts: Why use const variables instead of preprocessor directives when programming embedded with C++

texts:
I read on here that when programming with C++, const variables are better than preprocessor directives, ie #define, for declaring constants. I'm confused about why that is the case.
I understand that a const variable would be stored in static memory, whereas a preprocessor directive would become a literal, and possibly an immediate in assembly, but I don't see why that is a disadvantage.
I've also seen that inline functions are better than macros, but I'm confused about what is the difference.
Thanks!


texts:
I'm looking for a manufacture ID for this 6-pin SMD power connector.

Anything will help, even a category to dig through on mouser/digikey/fanell.

2 Vcc
2 gnd
2 temp sensor


texts: Use different footprint for a SATA connector

texts:
I am designing an Linux Board which needs a SATA connector.

Now im faced to choose between 2.5 HDD SATA connectors and the new mSATA (mini PCI express) connectors.

For compatiblity and usuabillity purposes, i would like to use or foreseen both of them in the design. So that i can choose during production which one i would like to have soldered.

Now the important question:

As i know, SATA is a more cricital Data Interface. It has to be an impedance controlled differential line.
What is the best practce to connect these two footprints on my board?

My first idea was: CPU ---> Con#1 -[0R Res]------> Con#2
What do you think about that?
I would use the 0-Ohm Resistor, because otherwise there is a Stub from Con#1 to Con#2 and this would produce reflections and impedance missmatch wich resulst or can result in a ringing Dataline.

Whats the best practice to solve this problem?

Thank you!


texts:
Recently, I am trying to simulate load dump(24 system 5b) by Pspice for automotive and then would like to check whether the current project that is designed from ex colleague and resigned has any room to improve or cost down.
My Load dump test requirement
UA=27V
Us*=57
Tr=10ms
Td=350ms
Ri=1 ohm
TVS P/N: SLD6S33A https://www.littelfuse.com/~/media/electronics/datasheets/tvs_diodes/littelfuse_tvs_diode_sld6s_datasheet.pdf.pdf

Here is my simulation step by step
1.Load dump waveform is from Ltspice website
https://www.analog.com/en/technical-articles/ltspice-models-of-iso-7637-2-iso-16750-2-transients.html
2.run simulation and export waveform text file
3.using Pspice PWL source to simulate my current project

simulation result as below .
Green line: load dump
Red line: TVS clamp V
Blue line: clamp current

My question is

How I estimate TVS(VR1) power dissipation from Pspice result?
Here is some estimated result by Pspice

to integral TVS W=V*I
Pspice command>>S(V(VR1:C)*I(VR1:C)) . S meaning is integral
Result is 50W

to integral TVS W=V*I/2(half peak current).
Idea from ST design reference :Protection of automotive electronics from electrical hazards
Pspice command>>S(V(VR1:C)*I(VR1:C))
Result is 25W

Using Pspice evaluation measurement function “PowerDissipation_mW”
Here is its description.
Total Power dissipation in mW during the final 'Period' of time.
Find the difference between the final Y value of the trace and
the Y value one period before that.(Can be used to calculate total power dissipation in mW, if the first trace is the integral of V(load)*I(load).)

Result is 125W
which those three results are more approaching at real application?

How could I know the TVS Peak Pulse Power value if td(mS) at datasheet is not shown in my real application. For example : my test td is 350ms but datasheet only show the MAX. Td is 100ms


texts:
Very new to this so please forgive any noob type statements

I have an AC plug in door bell, it produces a low voltage AC signal to a speaker.

I want to plum this into a Arduino GPIO so I know when the door bell is pressed

Am I safe just to hook this up or will this burn my home down?


texts:
I am trying to make a "laser gun range" like the ones you see at carnivals for my embedded systems class at school. However, I am having trouble because I do not know how to construct the "target". I want to be able to point a "gun" at a target ranging from 4cm to 0.5cm in radius, and I do not know how to detect a laser pointer over that range. CdS photoresistors are very small. I have also looked at IR but as far as I know you cannot focus it. I need help in coming up with a detection method. Bonus points if I can detect whether someone hits the center or edge. If necessary, I can also switch to mechanical Nerf gun range, but then I have to come up with a target with moving parts and have to detect how many bullets were shot and if the target is down somehow.

EDIT: I found the exact product I want in that it can detect laser shots but I have no idea how it works. http://www.youtube.com/watch?feature=player_embedded&v=q9_qMxHj0Mw

Background: The focus of the course is "the correct way" to write programs that run on small microcontrollers using state machines. For the end project we have to create a game that uses an 2x20 character LCD, a 16-button keypad, an LED, a button, a speaker, and a seven-segment display all on an ATmega32, which shares a similar peripheral set with the Arduino. I can even use an Arduino Mega with the condition that I write all code myself. (no Arduino.h) I know how to use all these devices and shift registers to give me more I/O. I just need an idea to implement.


texts:
I am using Multisim to design the first stage of an analog signal processing block.

I am using the Op-Amp AD797AR from Analog Devices. I am trying to check if the opamp is inverting unity gain stable.

I have the following schematic

My input is a sine wave of 100 KHz peak of 10 mV but the output seems to be unstable.

How do I ensure stability for the AD797AR? What are some things I can check to ensure stability?


texts: A question about differential measurement system

texts:
Below represents a differential measurement system for a data-acquisition:

As far as I understood, in a differential measurement system neither the outputs of the signals nor the inputs to the differential amplifier is tied to ground. That's why many places I read that this makes it immune to ground noise.

But there is still a measurement ground (AI GND and G) for the system.

My question is about the differential/instrumentation amplifier part:

Does such an amplifier above measures the:

1-) voltage difference between the point A and B directly(without any reference) ?

or

(voltage difference between A and G) - (voltage difference between B and G) ?

I can already see both above mathematically equivalent. But does sometimes this measurement ground G is also tied to earth ground which might be bouncing(?).

2-) Is the practice of connecting AI GND and G to prevent exceeding common mode voltages? What happens if AI GND and G are not connected and both signal and measurement side ground is not connected to earth?

3-) Should the point G never be tied to the "earth ground" in any side? If it is, what would be the consequences? Or is doesn't matter?


texts: Turning on a latch circuit with a piezo sensor?

texts:
I am trying to build a relatively 'simple' circuit with a piezo sensor that turns on an LED for ~10-20 seconds after it has been tapped.
In the off-state the circuit should use zero current to preserve battery life.
I would also like to avoid any ICs. Just some simple capacitors/resistors/mosfets etc.
I have tried a few different latch circuits - which seem to work fine with a normal button but I am not able to get them to work with the piezo sensor.
What would be the best approach to this?


texts: Replace U.FL connecter with a wire antenna

texts: I have an XBee module with a U.FL. connecter. Is it possible to solder an appropriate wire antenna to this module (without buying a new module with a wire antenna)? Since U.FL. has 2 connections and wire antenna needs just one, how do I do it? (My knowledge on antennas are low.)


texts: Does oxidized copper conduct electricity?

texts:
When the surface of copper turns that greenish oxidized color, does the resistance to current flow increase or isn't affected?

For instance if the point of contact is secure and clean but bare visible copper wire has oxidized will it still conduct electricity no problem?

Like this ground wire in my car. The resistance to negative of the battery reads 0 \$ \Omega \$ as well as from both ends of the cable itself.


texts: Sharp IR Distance Sensor gives the wrong readings

texts:
I am using the SHARP GP2Y0A21YK0F IR distance sensor. According to the datasheet, the output voltage to distance graph should look as follows:

I attached the sensor to a power source straight from Arduino 5V output, so the power source is relatively steady. The sensor's analog output is attached to a multimeter to check the output voltage for the varying distances of a white sheet in front of the sensor.

Until approximately 45cm distance of the white sheet from the sensor, the sensor works fine. The multimeter reads are consistent with the graph's curve (except the 0cm reading). But after 45cm, the voltage goes up instead of decreasing further, until it reaches 1.57V, when there is no object in front of the sensor.

My readings of the multimeter are as follows:

    Distance[cm]      Voltage[V]

    0                 1.7
    5                 3.10
    10                2.45
    15                1.9
    20                1.36
    25                1.17
    30                1.05
    35                1.02
    40                1.00
    45                1.01
    50                1.03
    55                1.06
    60                1.10
    65                1.12
    70                1.16
    75                1.21
    80                1.25
    infinity          1.57

I understand that for distances greater than 45cm the readings can be off because of effects caused by the surroundings (even though my testing environment is a closed clean room, but still maybe something causes faulty readings). What bothers me most is the voltage readings when no objects are in range. The sensor outputs 1.57V which is the same as 15-20cm range voltage, which can be problematic for my project as I intend to measure distances in the 10-40cm range.

What could be wrong?


texts: Is an ethernet switch considered as an ASIC?

texts:
I work as an electronic reliability engineer. In order to estimate the
reliability of integrated circuits, I need to know their type. Thus my question.

Is this ethernet switch Marvell Link Street-88E6341 considered an ASIC, or it is simply a digital IC?

EDIT : It appears that this IC is more like an ASSP. Here is the définition of an ASSP from wikipedia
https://en.wikipedia.org/wiki/Application-specific_integrated_circuit

An application specific standard product or ASSP is an integrated circuit that implements a specific function that appeals to a wide market. As opposed to ASICs that combine a collection of functions and are designed by or for one customer, ASSPs are available as off-the-shelf components. ASSPs are used in all industries, from automotive to communications.[citation needed] As a general rule, if you can find a design in a data book, then it is probably not an ASIC, but there are some exceptions.

For example, two ICs that might or might not be considered ASICs are a controller chip for a PC and a chip for a modem. Both of these examples are specific to an application (which is typical of an ASIC) but are sold to many different system vendors (which is typical of standard parts). ASICs such as these are sometimes called Application-Specific Standard Products (ASSPs).

Examples of ASSPs are encoding/decoding chip, standalone USB interface chip, etc.

IEEE used to publish an ASSP magazine,[2] which was renamed to IEEE Signal Processing Magazine in 1990.


texts:
I hope my question is not too stupid.
I'm controlling a brushed 48V 50A motor with a motor controller and I use two gel batteries as a power supply.

I would like to use a low power signal to switch on and off the power circuit, and for this reason I've bought a solenoid contactor (the coil works at 12v, the contacts are rated up to 500A).
The contactor connectors open and close the positive main wire and it stays closed for all the working time (it is placed between the positive battery lead and the motor controller).

This is the solenoid: https://www.amazon.it/gp/aw/d/B01N49AYTN?psc=1&ref=ppx_pop_mob_b_asin_image#

The contactor is on all the time, and for this reason I realized that the temperature is very high (max 60 degrees).

Is it normal? Or should the contactor be closed only for short periods of time?


texts: Is MC8051 is a microprocessor with some components on chip?

texts:
The 8051 microcontroller is a microprocessor with RAM, ROM, I/O ports, timers, and serial ports on chip.

Is that the correct distinction between a microprocessor and microcontroller?


texts: Best way to power a circuit from an unknown number of battery cells?

texts:
I'm designing a circuit to monitor the performance of lithium polymer battery cells and am stuck on the best way to power it. The battery packs could have between 2 and 8 cells and are supplied pre-wired in series with a primary power connector (pack +ve  and -ve) and secondary balance connector (pack -ve  plus a tap on the  +ve from each cell). My circuit will hook up to to the balance connector so that I can monitor individual cell voltages and I'd also like to power it from this connector both for convenience and because the primary power connector will be in use. So I have a 9-pin header where anywhere between 3 and 9 pins will be connected depending on how many cells are in the battery. I've built similar circuits in the past and used a couple of different approaches, but don't think either is ideal and would like to get opinions on a better design. Here's what I've done in the past...

The simplest solution is to power the board from pins 1 and 3 of the header (pack -ve and cell #2 +ve). This will always provide 6v to 8.4v depending on the state of  charge of the pack, plenty to run a 5v LDO. The problem with this  approach is that it is actively unbalancing the pack, by drawing power from only the first two cells. This doesn't seem like a very sensible thing to do with a lithium polymer pack as they're notoriously volatile.

Another solution I've used in the past is to connect all the cell +ves together via a diode and use this common cathode and pack -ve for power. This will always provide the full pack voltage to the board, but I'm concerned about what the leakage current through the reverse biased diodes will do to the pack.

Is anyone aware of a better solution to this?


texts: Relationship between the circuit bandwidth and the gain for an inverter op amp

texts: do you know the relationship between those two quantities, for an inverter configuration of the op amp. I know graphs, but i do not know any equation or function that relates those two quantities.


texts: Which speaker is better for an application based on it's datasheet

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Given two speakers and their datasheets what should I be looking at to determine if one is better for me than the other?  I realize this could be a broad question, but I'll frame it in my context.  I'm mainly interested in the 100Hz to 400Hz range, I don't care too much to go higher, lower might be nice but not a requirement.  Currently I'm using this 4" speaker from Dayton, here's it's datasheet.

My problem is now I want to get a little more volume for my signal without the speaker distorting.  I have plenty of output power left in my amp, but my louder signal peaks seem to be physically pushing the speaker out and making an odd distorted sound.  I did achieve more volume by using a compressor the other day although I'm still learning how to adjust it.

Back to the speaker though this one has a fairly flat response in my frequency range, should I be looking for a speaker that can give more spl in the frequency response chart?  Is something like Xmax (I think the maximum excursion) going to let me drive the speaker louder since it has more room to move?

I spent some time trying to learn about the values in the datasheet to craft a box using some speaker software, but I'm still not clear how to evaluate two speakers against each other for my application.   For instance I'm looking at this speaker which looks like it has more SPL and more excursion, plus more power handling, but is it really going to be better?


texts: How do I recharge a battery using a small solar cell

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I need to partially recharge a 3.7V, 2.7Wh battery. The Solar cell's output is roughly 1V with a current of 1-2 micro-Amps. I don't know hot to construct this circuit. I figure I need to use a diode, but other than that I am quite lost. What should I do?
I am mainly looking for a way to store the energy. It doesn't have to be the battery mentioned above, but the solar cell's output can't be altered due to the lighting conditions.


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I am upgrading the lighting in a model with simple circuit which has 17 LEDs (approximately) plus one or two 555 timers. Presently, everything is powered by 3 AAA batteries. It drains between 150 and 250 mA (depending on how many LEDs I switch on).
Heads up: I'm new to electronics and lighting, so please bear with me anyway if the questions if not challenging enough :)
Once the circuit is done, I plan to extend it with two variations:

Arduino Version: connect the LED circuit directly to the output pins (5V) of an Arduino board, with a resistor in each wire to compensate for the +0.5V excess.
USB wired powered version, using a wall charger USB that provides 5V 800mA.

My question is: What should I do to adequately protect the circuit when using the USB version? Do I need a voltage regulator? If yes, what type/part?
As per my research, I don't need a regulator for the Android version, but I'm not 100% sure (comments on that will be welcomed too).
Edit: As requested, I've added a simplified schematic. The final version will have more leds and probably drain arround 200mA-250mA.