texts: What is causing soldered connections to the power and ground planes to fail specification?

texts:
Possible Duplicate:
  through hole soldering vertical fill problem ground and pwer planes connected points

We have a PCB having three AD584 (TO5-8 Package) and two DC-DC converters THD 10-2423.

PCB has total 6 layers including top and bottom planes.
Three pins of AD584 are connected to ground on two internal ground plans through spokes as well as top and bottom planes through spokes.
Four pins each of DC-DC Converter are connected to ground planes and rest of four connected to power planes.
Components are new and have clean pins and have shiny appearance.
Components as well as PCB surface finish are pro lead compatible.
AD584TH pin diameter is 0.45mm and Plated through hole internal diameter is 0.85mm.
DC-DC Converter diameter is 0.5mm and Plated through hole internal diameter is 1.0mm.

We are trying to solder these components manually as well as passing through wave solder machine. After soldering, solder joints on these ground and power plane connected pins don’t fulfill acceptable criteria of IPC-A-610D class III 7.5.5.1 Sported Holes – solder- vertical fill (A). Rest of the 5 pins on these three AD584 meet target condition in this respect (i.e. there is 100% fill).

For manual soldering, we are using bottom heat plate for PCB preheating up to 120°C and soldering station temperature set to 450°C (iron 150W).
For wave soldering machine, preheating temperature up to 120°C, peak temperature 245°C to 250°C and dip time 5-6 seconds.
Possible reasons for this problem and recommendations for its solution are required.


texts: Battery Elimination Circuit Powering Flight Controller

texts:
I am putting together a quadcopter, and one of the things I've stumbled across that I don't quite understand is Battery Elimination Circuits (BECs).

The Flight Controller on my quadcopter is a modded Arduino board with some motor pins and other sensors integrated into it. The Flight Controller is capable of being fed anything from 12V to 5V. I have been feeding it 12V straight out of my LiPo battery, which it regulates down to 5V and continues merrily on its way.

Now, the Electronic Speed Controllers (ESCs) that drive the motors each contain an integrated BEC. From a post on this site under the "Discussions" tab, one guy claims that the most common thing to do is use the BEC to power the Flight Controller.

So it seems to me like the BEC is kicking 5V back to the flight controller. Is that good enough? Do I need to worry about low current or low voltage conditions? It's pretty important the Flight Controller say running.

I have read a few links about BEC's:

From this link, I think I understand that the voltage regulators in BEC's are generally linear, which is going to use more power than a switching power supply, but then in the comments, the guy who asked the question said "thanks... I'll go with a BEC." I'm not sure what I'm missing there.

So I currently have four ESCs, each with three pins (Signal, V, GND) connecting to my Flight Controller. I also have 12V straight from the battery connecting to my Flight Controller board, which is regulated down to 5V.

Is this wasteful? Wise? Should I remove the (V, GND) pins to the ESCs and only keep the signal pins? I'm spinning my wheels here because I'm obviously missing something.

What is best power and weight-wise?

Any advice is appreciated. I didn't know BECs existed in the not-too-distant past.


texts: I have 2 xbee series 2s that I want to talk to each other with ardunios. I have the ardunio xbee shields but I can't find any good resources on how to get them to communicate together. So how would I configure these to communicate with each other? As a lot of the resources i've found use the typical sparkfun shield/breakout board on another pin.


texts: LTSpice resonant circuit simulation non-idealities

texts:
I just simulated the following circuit in ltspice XVII:

A parallel resonant circuit is tuned to 125KHz with varying capacitor sizes. Then a voltage divider is formed with a resistor.

These are my settings for the inductor, capacitor and in the Tool Panel. In my understanding, this should now simulate an ideal inductor without losses and the same for the capacitor.

Using ordinary AC-calculation, the voltage over the resonant circuit should be:

$$ V_{res} = V1 * \frac{\frac{1}{\frac{1}{j \omega L} + j \omega C}}{R + \frac{1}{\frac{1}{j \omega L} + j \omega C}} $$
$$ = V1 * \frac{1}{R*(j \omega C + \frac{1}{j \omega L}) + 1} = V1 * \frac{1}{j R*(\omega C - \frac{1}{\omega L}) + 1} $$
$$ \Rightarrow V_{res} = V1 \quad \forall \quad \omega C = \frac{1}{\omega L} \Rightarrow L = \frac{1}{C \omega^2} $$

So at resonance, when \$ \omega C = 1/(\omega L) \$ the resonant circuit poses an infinite resistance and \$ V_{res} = V1 \$.

However, LTSpice gives the following simulation results (where smaller C values yield larger amplitudes):

Now I'm wondering how this is calculated by LTSpice. Are there any non idealities that I didn't switch off? Or am I missing something in my calculation?

Any hints would be very appreciated,
Thanks in advance.


texts:
I'm looking for a battery holder for 3-4 AA or AAA batteries in series (I'm targeting an output voltage of 4.5~6V).

I found a variety of options on Mouser, but the problem is I can't tell if they batteries are wired up in parallel or in series. What part of the datasheet should I be looking for to determine the output voltage? Or is there a given standard somewhere which describes what the wiring is for each holder type?

Option 1: 2x2 AAA battery holder

Option 2: 4x1 AA battery holder

Option 3: 2x2 AA battery holder

Option 4: Any other recommendations you know will work


texts: Suitable 12VDC Communication protocol for untwisted unshielded long-ish wire length?

texts:
What would be a reliable and simple tranceiver interface/protocol for board to board serial communication at about 100ft. [9600bps or lower is fine.]

The two-lead communication wiring cannot be changed and is un-twisted, unshielded wire [~25pf/ft] in commercial buildings.

12VDC rail is already available.

Specifically, I've looked at Modbus/RS485 and RS232. Most available and low cost [~$0.50] chips seem to either run 3V3 or use capacitor charge pumps to level shift to 6V.

What's typically used in these scenarios?


texts: How to make a positive pulse with a button?

texts:
I want to make a circuit that sends a positive pulse that gets high for a few nano seconds when I push the button and then goes to low. I want this to happen even if I hold the button down without releasing it.

I tried some circuits like the one shot 555 and just using a capacitor, but the voltage didn't go down when I held the button.

Thanks.


texts: connect Micron SDRAM to STM32H7 FMC but what should I do with DQM pin?

texts:
I plan to connect SDRAM from MICRON MT48LC series ( datasheet. The pin connection diagram is automatic generate by STM32CubeMX ( STM32H743 ). The setting is an 8-bit data bus, a 13-bit address, 4 banks, and Clock and chip enable ( SDCKE0 + SDNE0 )

However, I found that there is no pin to connect to Micron DQM pin.
I saw some suggestions that if there is no use for DQM pin. It should connect to the GND. (waclawek.jan answer) and also the Micron suggested to left it NC ( float ) ( the section "Unused DQ Pin )

When I dig into the Truth Table of Command and DQ pin. this is the table

DQM signal is used for READ and WRITE operations and also "Write enable/output enable" and "Write inhibit/output High-Z". It seems that DQM should connect to the GND for logic "L" is better than making it float. This is the thing that is very unclear how could I connect STM32 with Micon SDRAM DQM pin


texts: What is smallest addressable value in an octal number called?

texts:
In a binary number, the smallest addressable value is called as a bit.

In a decimal number, the smallest addressable value is called as a digit.

In an octal number, what is the smallest addressable value called as?


texts: What does this "Not Installed" symbol mean on the data sheet?

texts:
I am designing a circuit that uses the TI TPS561201 buck converter. Reading the data sheet, I am slightly confused with the notation of "Not Installed" next to some of the components.
Questions:

What is the purpose of including an uninstalled component?
In what scenario would I include the capacitors in my circuit?

With capacitor C4, for example, why would the component be drawn in the schematic but then labeled "Not Installed"? I have attached the schematic with the symbols highlighted.


texts: The possibility of ESD in an isolated, mobile system

texts:
When you have an isolated, battery powered device, then shouldn't you expect ESD?

Let's say I have two boards connected with each other through cables and connectors. The components on the PCBs are powered by batteries, and all of these are installed in a plastic enclosure. So this is a system with floating ground.

I heard that self-discharge does not occur in an isolated system. But is it really the case? When the device is transported and mounted somewhere,    all metals and insulators must have been charged up. Some of those should have different polarity. Then shouldn't you expect, theoretically and practically, ESD through air, or through a thin material at some point?

What if the device is moved frequently? In that case cables, connectors don't have stable contact. So charges can move from one to another suddenly. Don't you have to expect ESD through sudden contact between the cables, enclosure, the boards, and so on?


texts: What happens if PD tries to consume more than allowed PSE power provided?

texts:
What happens if a Powered Device (PD) tries to consume more than allowed (Power Sourcing Equipment) PSE power provided, even though it has requested a set amount of power?

http://www.ti.com/lit/df/tidrta2/tidrta2.pdf

Example: Let's say the load on the output wanted 40V @ 1.3A but the output was rated for 40V @ 1.15A


texts: What wattage solar panel required for AC 1000 watts

texts: If my house load is 1000 Watts AC/220V, then 1000 Watts DC/12V solar panels is not enough. What wattage solar panel would be required for AC 1000 watts?


texts: Advice on going from rat's nest to routed PCB

texts:
Can anyone offer any useful strategies on going from a rat's nest to a routed PCB?

(I'm using Eagle and aiming to make single/double sided PCBs at home)

Drawing the schematic is fine, but when it comes to routing the tracks, it feels like unravelling a giant ball of wool.


texts: What if a single transistor fails in a microprocessor?

texts:
What if a single transistor fails in a microprocessor or in RAM?

By failure I mean it completely stops working (due to overheating or some other reason) or gives incorrect output.

A single failure can change the specified microprocessor opcode to be read as some other instruction or mangle up the intended memory address in RAM and things can go downhill from there.

What safeguard/recovery strategy does a computer have against this?


texts: 1 pulse toggle with simple non programmable electronics

texts:
I need to create a simple circuit that toggles when one pulses a push button and then stays on no matter what you do with the push button again. The toggle will reset when the system is powered off (starts off)

Any clues where to start from ? I've playing with relays,push buttons and those but .. cannot really get it. I'm currently working with logic gates to see where it leads..

Any idea ?


texts: How to find Steinmetz parameters from datasheet?

texts:
Given a certain core material I would like to know where and how I can extract the Steinmetz parameter from its datasheet. Hope someone can help me out. Thanks.

datasheet:

https://en.tdk.eu/inf/80/db/fer_13/R4180x2620x1250.pdf

https://en.tdk.eu/download/528882/6a0da25e2745be5c13b587b3d4a8de48/pdf-n87.pdf


texts:
These batteries are rated from 4.2V to 2.7V. A typical discharge graph is here.

My question is when to stop draining? What is the best practice? Should I stop at 3.2V or drive it down to 2.8V? It seems to be very little charge is left after 3.3V but I want to ask to experts about the best practice.


texts: Differential and common mode over-range indicator for In-amp

texts: I need some advice with differential and common-mode over-range indication. I have a device with In-amp and I would like to add a Led or buzzer for differential and common-mode over-range indication. I have easy access to all nodes as this In-amp is not an IC but 3 separate op-amps. The device is powered from SMPS with +/- 6.5V rails. My initial thought is to use two window comparators. The first one using Va as input and the second using Vb as input. I would use a potential divider to set Vref_high at approx. 3V and Vref_low at approx. -3V using existing power rail from SMPS (Vref should not drift). One thing I do not like about this solution is the fact that I would have to use an additional quad op-amp IC. I am wondering if there is a simpler solution to my problem.


texts:
I recently got an alarm clock from goodwill and took it apart and am probably going to use the display for some tests. Here is a picture of the front of the display:

The text on the left is YC-60525S   3
The text on the right is 94HB
On the back is WS6055 L S and 0306

Here is the display schematic I made as a PDF.

You will notice that pins 23-29 were never connected to the clock's other PCB; although pins 22 and 23 are soldered together. Also worth noting is that pins 7 and 8 are never used. And lastly a, d, e, f, and g do not currently function in any sense on digit 1 (hence '1' is the only digit it can make).

My problem is that I was messing around with the unused pins on the right of the board and managed to do a couple different things.

I duplicated the controls Pin 1 had as ground to Pin 29 (Red/Purple in the PDF).
I moved the majority of controls Pin 2 had as ground to Pin 25, leaving only control of the 1st digit to Pin 2 (Blue/Black in the PDF).

I am unsure what did to cause the board to change its configuration. I was trying to be pretty thorough labeling the pins, and at one point I brought in a second voltage line. I would like to know why/how this occurred, but also how I can then manipulate the boards settings to my liking.


texts: Send data to an Arduino by using an audio cable

texts:
I want to send some Data to my Arduino by using the audio jack of my smartphone/computer.
(USB is no option, since my smartphone does not support USB Host mode and I also don't want to go wireless or use a modem)

I have allready connected my computer to my Arduino and created a squarewave as the audio signal. But what the Arduino saw, was something like the derivative of the squarewave. Or a declining voltage of capacitor. I haven't lookt at it at a high enough sampling rate to specify this.
(I didn't use an amplificator)

What do I have to do, to get the Arduino to read 0 and 1, like the signal I created?


texts: Mobile microphone input data throughput via audio jack?

texts:
does anyone know how much data could be transferred through audio jack for app to process into bytes?

I'm wondering how many different buttons could  be mapped and processed using mic input? (Many headphones with microphones use 3 buttons: volume up/down and calling button)

All processing should be done in realtime.

Thank you


texts: Testing Ethernet cable with a signal generator and scope

texts: I have been having some problems with my Ethernet lately and would like to test the cable.  I was thinking I could borrow a signal generator and oscilloscope from work and get them hooked up to the cable and send a 25 MHz sine wave down the line and measure the attenuation at the other end.  Does this make sense?  How should I go about connecting the coax from the signal generator and scope to an RJ-45?


texts: Oscillation on opamp output with P-mosfet

texts:
OPA1611 without C15 1nF - between IN- and OUT of OPAMP, measured in "TP-PRZEWOD"

Schematic1

Schematic2 - supply

OPA1611 + 1nF between IN- and OUT of OPAMP, measured in "TP-PRZEWOD"

PCB layout

Output of OPAMP
I have tested:

3 differents OPAMPs - TL071; OPA277; OPA1611; uA741
tested differents capacitor between IN- and OUT of opamp (22pF;33pF;47pF;100pF;1nF;10nF;100nF)
tested mosfet driven directly by OPAMP and via NPN transistor - there are no differences between circuits. Always oscillations,
tested R2 1k; 10k
R5 - tested 47R, 100R

About circuit. Its tool for testing laboratory cables (banana plug).
X1 - its connector for power supply. 5V 16A. Aimted DC/DC 5-12/12 for opamp supply.
C14 - 1000uF
CSR-2.0-R010 its shunt resistor - 10mΩ.
PMosfet - IXTH120P065T.
R_I - selectable resistor 10R;50R;80R;100R - 1A;5A;8A;10A testing current.
PR1 - calibration 1mA across T1.
Its problem with OPAMP, layout or...?
Have a good day

OPA1611 + 1nF between IN- and OUT of opamp. Measured in TP-PRZEWOD

OPA1611 + 1nF between IN- and OUT of opamp. Measured in TP-PRZEWOD


texts:
I hope I've come to the right forum about this...

I'm planning on building an e-bike using RC components, except I'm not going to use a transmitter and receiver.  Instead, I'll use a Servo Tester to control the speed of my brush-less DC motor.  The motor is driven by an ESC (Electronic Speed Controller) which in turn is controlled by the Servo Tester.

I'm planing on using LiPo 6s(22.2V) battery.

Ive researched for several days now and came found that I need a BEC (Battery Eliminator Circuit) to lower the 22.2V to 5V so the servo tester doesn't get damaged.

Now Im just wondering about the current.

Ive seen some people have a separate battery for the servo tester which seems to be the simplest solution but I want to be effcient and use my main battery for that.

Im thinking of splitting the cables to go to both ESC and BEC -> ServoTester.

I know that the setup is going to draw a lot of current maybe up to 50A or more (not continuously) so then I'm wondering if that current is going to go through the BEC and then into the servo tester and fry it. Or will most of the current choose to go through the ESC and only what is needed goes through the BEC?

PS. Im not an electrician x)

This is how Im planning to connect everything Please dont laugh:

Will this setup work or should I stop trying before I get hurt? :)

  EDIT

The components specs and explanation:

Motor: Brushless 190 rpm/V 90A max Resitsance is unknown Motor link
ESC(Electronic Speed Controller) this decides in which coils in the motor the current will go through making it spin. 120-180A 18.5-44.4V ESC link
BEC(BatteryEliminatorCircuit) lowers output voltage to 5V BEC Link


texts: Is it ok to bend a VIA in a Flex Printed Circuit?

texts:
On a Flex Printed Circuit (FPC) made out of Kapton polyimide, will anything bad happen if I put a VIA in a part of the FPC that has to bend?

VIA size: 0.2 mm hole diameter in 0.4 mm copper diameter
FPC bend radius: 0.7 mm
Kapton thickness: 0.2 mm
Copper weight: either 2 oz or 1 oz (I haven't decided yet)


texts: Are pins of WOG bridge package numbered?

texts:
The WOG package used for a diode bridge looks like this:

As I'm preparing a PCB layout footprint for this device, I need to assign pin numbers. Those pin numbers map to the schematic and ensure the pins are connected to the right circuit nodes in the PCB layout.

In studying the datasheet and doing a general web search on "wog package", I can't find mention of the pin numbering for the package.

Am I missing something?

If not and it's up to me to decide, I'd be inclined to make the top pin (+) pin 1, and then number counter-clockwise as viewed from the top. My rationale is that when viewing the component from the top, the printing is aligned such that the package flat is at a 45 degree angle and the (+) pin is at the top. Does that seem consistent with convention?

This would produce the following mapping:

1: \$+\$
2: ~ (A)
3: \$-\$
4: ~ (B)


texts: How to simulate lossy power line on LTSpice?

texts:
I need to add lossy power line in LTSpice model to be able to simulate the signal transmission over this line.

This means that I will need two components:

230 VAC power source model
asset power line model

Like that:

I did find ideal lossless transmission line model:

But this is not that I need. Is there any off the shelf solution?

If not: how do I build it my self?


texts:
I am using a step up transformer and I am getting a weird discontinuity in the secondary output. Has anyone seen anything like this before? I cant figure out what might cause this. In a one test setup I can get a nice sinusoidal waveform with the same input voltage when I have a large resistive load (500ohms) on the secondary. When I hook up to this inductive load (5ohms esr) I am getting the weird waveform. Is it possible the output impedance of the transformer is too high for the lower impedance load? Thank you for any insights.

Dark Blue: Primary Current, Light Blue: Secondary Current, Pink: Secondary Voltage, Green: Primary Voltage


texts: What is the advantages of InGaAs infrared image sensors?

texts:
I am currently searching the InGaAs material for infrared imaging usage. I have read some papers about it. It seems a new one. But I can not get real advantages of it, yet. What is the basic reason(motivation) of usage this material in infrared imaging systems?

Best Regards,


texts:
I have a HW question with a simple op amp circuit and was wondering if I could get some help. Here is a quick glance at the problem:

and here is my attempt to solve it:

I am not sure if my signs are correct when solving it. Also should I solve for Vo(t) for each case or did I do it correctly by solving for the formula for a general Vi and then graphing each result separately. Could I also receive some insight on part B. I am not sure how to go about it. the only thing I am thinking is that I multiply Vo(t) by tau and the RC's cancel out but this doesn't seem correct.

Any help appreciated. Thank you!


texts:
There is a device which is powered and also outputs signal by its TRS connector as shown below:

This TRS connector needs a female correspondent for my circuit.
I made a small board and need to add my schematics the female jack of this TRS.

In KiCad there is the following symbol:

But Im not sure if it is a TRS female jack, since 2 and 1 are seems connected.

Is this how it supposed to be?


texts: Vivado "Export hardware" packs unknown bitstream

texts:
We have a Zynq project in Vivado 2017.4. I can generate the bitstream, in proj/proj.runs/impl_1/mybitstream.bit.

Then I want to import that configuration to my petalinux project so I use File > Export > Export Hardware..., make sure the Include bitstream is checked and keep the the Export location: <local to project> (which ends up in proj/proj.sdk).

That gives me a proj/proj.sdk/proj.hdf file, but when I unzip it, file mybitstream.bit is not the one in proj.runs/impl_1! (it actually is one from a previous build).

I have to import hardware description then manually overwrite the old bitstream:

$ petalinux-config --get-hw-description=proj/proj.sdk
$ cp proj/proj.runs/impl_1/mybitstream.bit petalinux-proj/project-spec/hw-description/

Does anybody know where the Export hardware function gets the bitstream? Maybe there is a way to "clean" a Vivado project? (there is no such option in Vivado).
So far we only modified logic in the PL but I fear that, when we add some BRAM or change some addresses, the whole hardware description will be wrong...


texts:
The circuit is a MCU triggered, capacitor based fan speed controller.

The circuit works fine when a single triac is connected but when both triacs are wired and triggered alternately, any of the triac fails randomly by shorting. Initial load is a 60W incandescent bulb.

The triac gate takes close to 50mA through optocoupler. This seems much higher as the triac has senstive gate which can be triggered by a low power MCU.

Kindly help.

MOC3041 Datasheet
https://www.fairchildsemi.com/datasheets/MO/MOC3041M.pdf


texts:
Need to connect two boards together. Initially I thought about using a ribbon cable like this one, but everything I found was significantly longer than what I needed (~30mm max). Are there any other options to achieve a similar result, that I'm maybe completely missing?

LE: I need to connect four signals, one I2C bus, ground and vcc. Current consumption is around 10mA.


texts: Register file in Verilog, How to make it so reads only happen on negedge

texts:
So this is my current code.

  module top
  (input clk,
   input reset,
   input write,
   input [4:0] wrAddr,
   input [31:0] wrData,
   input [4:0] rdAddrA,
   output [31:0] rdDataA,
   input [4:0] rdAddrB,
   output [31:0] rdDataB);

   reg [31:0]    regfile [0:31];

   assign rdDataA = regfile[rdAddrA];
   assign rdDataB = regfile[rdAddrB];

   integer   i;

   always @(posedge clk) begin
      if (reset) begin
            for (i = 0; i < 8; i = i + 1) begin
                regfile[i] <= 0;
            end
      end else begin
            if (write) regfile[wrAddr] <= wrData;
      end // else: !if(reset)
   end

    endmodule

It works fine, but it reads immediately.  I want to set this up so it reads only on the falling edge of the clock cycle.  I'm not sure how to add posedge and negedge blocks without running into issues with constant drivers.  Any tips on the proper way to do this would be great.  Thanks.


texts: Obstacle detection using an ultrasonic sensor and a PIC microcontroller

texts:
I'm trying to detect obstacles at a specific distance using an ultrasonic sensor which is interfaced with a PIC micro controller.

Ultrasonic sensor   = HC-SR04
PIC micro controller = PIC16F628A

This will turn on a LED when an obstacle placed in front of the ultrasonic sensor at a specific distance or distance less than that. In order to do that I have written the following assembly code. But it doesn't seems to be working as expected. The LED doesn't lit for any distance.

Here is the assembly code

PROCESSOR PIC16F628A
#INCLUDE <P16F628A.INC>
#INCLUDE <BANKSEL.INC>

CBLOCK 0x20 ; DEFINE VARIABLES USED
C1
d1
d2
d3
ENDC

ORG 0x00     ;RESET VECTOR
GOTO MAIN

MAIN
Bank0       ;goto bank0
CLRF PORTA          ;Initialize PORTA by setting output data latches
MOVLW 0x07          ;Turn comparators off and
MOVWF CMCON         ;enable pins for I/O functions

Bank1
bsf TRISA,7  ;set RA7 as input (ECHOIN)
BCF TRISA,1  ;SET RA1 AS OUTPUT (LED)
BCF TRISA,0  ;SET RA0 AS OUTPUT  (TRIGGER PULSE)
;CLRF TRISB   ;PORTB pins defined as outputs

CLRF C1 ; NOW C1 VALUE IS '00000000'

Bank0

MOVLW b'00000000' ; CLEAR W REGISTER INITIALLY

LOOP
CALL TRIG          ;START TRIGGER PULSE
BTFSC PORTA,7      ;CHECK ECHO OUT PIN STATE
GOTO COUNT         ;ECHO OUTPUT IS HIGH
CALL CHECKCOUNT    ; THIS WILL CHECK THE VALUE IN C1
GOTO LOOP

COUNT              ;THIS WILL COUNT THE TIME LENGTH OF ECHO PULSE
INCF C1,1          ;INCREASE C1 VALUE BY 1, SAVE IT IN C1
CALL DELAY         ;1mS DELAY
GOTO LOOP

CHECKCOUNT             ;THIS WILL CHECK THE 7TH BIT OF C1 REGISTER
BTFSC C1,7             ;IS 8TH BIT FILLED?
GOTO LEDON             ;YES
BCF PORTA,1            ;NO
L1
CLRF C1                ;CLEAR REGISTER TO WRITE NEXT COUNTED VALUE
RETURN

LEDON
BSF PORTA,1
GOTO L1

TRIG ;THIS WILL CREATE 10uS TRIG PULSE AT RB2 PIN WHICH IS CONNECTED TO TRIG PIN
     ; OF THE SENSOR
BSF PORTA,0
CALL DELAY10US
BCF PORTA,0
CALL DELAY60MS ;AVOID CREATING PULSE IN  t<50MS
RETURN

DELAY
; Delay = 0.001 seconds
; Clock frequency = 4 MHz

; Actual delay = 0.001 seconds = 1000 cycles
; Error = 0 %

            ;998 cycles
    movlw   0xC7
    movwf   d1
    movlw   0x01
    movwf   d2
Delay_0
    decfsz  d1, f
    goto    $+2
    decfsz  d2, f
    goto    Delay_0

            ;2 cycles
    goto    $+1
RETURN

DELAY10US
; Delay = 1e-006 seconds
; Clock frequency = 4 MHz

; Actual delay = 1e-006 seconds = 1 cycles
; Error = 0 %

            ;1 cycle
    nop

RETURN

DELAY60MS
; Delay = 0.06 seconds
; Clock frequency = 4 MHz

; Actual delay = 0.06 seconds = 60000 cycles
; Error = 0 %

                ;59998 cycles
    movlw   0xDF
    movwf   d1
    movlw   0x2F
    movwf   d2
Delay_1
    decfsz  d1, f
    goto    $+2
    decfsz  d2, f
    goto    Delay_1

            ;2 cycles
    goto    $+1

RETURN

END

Are there any modifications to do in this code to make it work properly? Or has anyone got a simpler code than this to do a this kind of job?
Thank you


texts: Measuring starting parameters of squirrel cage induction motor

texts:
I am trying to find some numerical solution for finding starting current and starting torque for three phase squirrel cage induction motor.

Some of the data I measured in energy meter such as

no load test: VA=81.40 , W=20.11 , P.F.=0.255
block rotor test: VA=899.7 , W=375.3 , P.F.=0.417

The motor rated voltage on the name plate is 150 V and rated frequency is 150 Hz. Power output is 275 W and 2 pole machine. I have some data which is starting torque 60% and starting current 570%.

Here I am confused on how to measure the starting torque and starting current value any way I need to calculate.
If it is possible by circle diagram then please tell me how because I have limited data. Any equation so that I can get solution by using RS-485 communication type energy meter.

How can I get the solution?


texts: I'm calculating basic amperage (W/V=A)  I have a track light with 33 LED lamps that is experiencing an unusually high failure rate.  When calculating amperage would I use the 120v that the entire lamp is using or would I use a low voltage amount such as 12v or 24v since the lamps have an integrated driver?


texts:
A device I own has this battery:

I need to replace it, because charging does not work anymore.
Its dimensions are 20mm x 30mm x 4mm.
Its being charged with +5V USB.
What's the term for this type of battery?


texts: Difference between nominal operating point and optimal operating point of induction machine

texts: I am trying to draw Heyland drawing for an induction machine where it is said that the nominal operating point is equal to the optimal operating point. I am confused about the difference between the two operating points. Further, how could this information be translated to the Heyland diagram?


texts:
I am having trouble identifying one of the two ICs on my dog's ultrasonic collar tag. The lettering on the 16-pin SOIC package was obscured by some sealant which I had to scrape away, leaving the markings quite faint, so it's possible I'm misreading them (and thus far I have found it impossible to get them to show up at all in a picture).

I can make out a TI logo, and there are three lines of markings which appear to read:

CM060B
49K _G4_  <-- That's an underlined G4
A995

The usual Google technique leads to lots of "In Stock!" and "Register to receive a quote" pages, but no datasheets.

Anyone know what this might be?

EDIT: The second IC on the tag is a quad two-input NAND gate. There is also some sort of crystal or oscillator in a tall, thin metal can (about the dimensions of a resistor but with both leads at the bottom); this appears to be the source of a very steady 40kHz sine wave. See What is this component on my dog's door opening collar? for a wide shot of the PCB with the glue still covering the IC in question.


texts: why are non isolated buck converters a safety risk with 120V DC?

texts:
So i've come to understand that buck converters CAN be used for 120V to 5V BUT they are not becuase they are often a safety risk. I also understand that they can be used if they are away from a consumer OR if they are used in an industrial scenario.

for example: it can be used with a ceiling fan becauase a consumer does not interact directly or near to the buck converter circuit.

why is a non-isolated buck converter unsafe with specifically a 120V connection? It is considered safe to move from 40V DC to DC , seemingly regardless of current flow.

looking to understand this better

Thanks

EDITTED (to specify use of non isolated buck converter)


texts: Atmel USB sends STALL packet after 1 minute

texts:
After one minute of time (inactive or active) the USB stack on my Atmel SAM4E-EK sends a USB STALL packet which basically kills the USB connection with the host. How can I prevent this from happening?

The host is a Windows 7 and the status of the USB packet received on the host (PC) is 0xC0000004 from endpoint address 0x84 (UDI_CDC_DATA_EP_IN_0) and one with the same status from 0x83 (UDI_CDC_COMM_EP_0). The USB device is a USB composite device with CDC and MSC enabled.

Atmel has a example project which is also a USB Composite Device with MSC + CDC and this too times out after a couple of minutes (3-4 minutes).


texts:
I'm salvaging parts from old computers, read the datasheet of those parts and try to understand the important things build stuff. While i now understand some crucial things about mosfets there is alot that i need to learn. Anyway i'm playing with the tlc5940 (16ch 12bit led driver) and i wanted to create a "animated" illumination for my room. I already created some led drivers with transistors , but also mosfets. Not logic level mosfets. To do so i needed to build a complex "Saturation" circuit involving other 2 transistors per Mosfet.

In my local electronics shop they on ly have higher voltage mosfets. Also on the websites i normally buy parts.

The salvaged mosfets are all N-type Logic level ... so perfect both for the raspberry and the Arduino.I can saturate them correctly, there is almost no voltage drop, they are really fast and they sink alot.

My question is:

Looking at the datasheet i could not find that big difference regarding each different mosfet. But they all have another number.I tought the amperage but some lower number mosfets have more amps.

05N03L  = 80 Ampere
07N03L  = 30 Ampere
15N03L  = 42 Ampere
32N03L  = 50 Ampere
46N03L
55N03L
60N03L

So what are those 2 numbers in front of the code?

N means N-type, L means logic level ... 03?

And most important question:

If i use different types of those mosfets with the tlc5940 could there be a SERIOUS problem or would that work nicely?

note: pullup 10k each ch, tlc with 6,8k resistor to let just sink enough to activate the mosfet, keep all channels under 3A.

Sample circuit using arduino pins

simulate this circuit – Schematic created using CircuitLab

And here using TLC5940NT

simulate this circuit


texts: Why it is necessary to put two 120 ohm termination resistors at each end of CAN transmission line respectively? Does it make an equivalent resistance of 60 ohm? (parallel resistors). Is it OK to put only a single resistor at any end or in middle of this transmission line?


texts: Insulation pull tabs on PCB to turn on a device for the first time

texts:
In some inexpensive electronic products like toys and remotes, there is a small piece of plastic sheet that disconnects a coin cell or button cell. Pulling out this plastic tab turns on the device, by connecting the battery.

Can a similar insulating tab be added to the PCB? Which kind of components can enable this? The two supply wires from the battery would be soldered to the PCB, so this tab needs to be on the PCB.


texts: I have an alarm system panel that uses 1000 ohms EOLR (10%, 1/2 watt). One of them has failed and I would like to know if I can replace it with a 1500 ohms (5%, 1/2 watt) EOLR. Is this acceptable or MUST it be replace with an 1000 ohms (5% or 10%, 1/2 watt) EOLR if all the other EOLRs remain as the original 1000 ohms EOLRs?


texts: Data Logic Levels Sent From Sensor Are Not Going All The Way Low

texts:
I'm having issues receiving data from a 3.3 volt logic level R503 Fingerprint Module that is sent via it's Tx pin using UART. The logic levels are converted to 5 volts using a bi-directional converter. When not plugged into the converter, the logic levels from the module are 2.6 volts in the high state and 0 volts in the low state (See image 1). When the sensor is connected to the converter, the logic levels from the module, measured on the low side of the converter, are 2.6 volts in the high state and 1.2 volts low state (See image 2). This results in the output from the converter to NOT be driven all the way low, therefore preventing the microcontroller from receiving any data. See image 3 for output from the level converter.
I am unable to determine the cause of this issue.  I have checked and used different cables, connectors, and power supplies. This issues is also present and can be reproduced on the only 2 sensors I have. Any help would be greatly appreciated!
Image 1: 1 volt/div - Tx pin Not connected level converter

Image 2: 1 volt/div - Tx pin connected to level converter. Measurement is taken at the low side of the converter.

Image 3: 2 volts/div - Tx pin connected to level converter. Measurement is taken at the high side of the converter.

EDIT: Added schematic


texts:
I have a question about ESD effect on MCU pins that troubles me.
MCU pins configured as input, that are not pulled low or high are likely to make trouble, and very likely to make trouble in case of an ESD pulse.

But what about:

MCU pins configured as tri-state?
MCU pins configured as output?
Would it make a design more robust to configure unused MCU pins as output?


texts: How to flip in/out off page connector in OrCAD

texts:
Is there any way to quickly flip the in/out direction of off page connectors in OrCAD (Allegro Design Entry CIS)?
I've run into the problem numerous times where I place a connector with a bunch of signals, then want to place its mate on another board.  Copy/paste the connector with all the signals, but then I have to delete and re-enter all of the signals to show that it is now an in instead of an out.

Notice I didn't even want to do all of the signals for this example because it is tedious.


texts: How should I write a feasibility study report?

texts: I may be called upon to write a feasibility study report for consumer hardware (to be manufactured) and/or a service to be offered to clients in the near term. What is the proper technique here? Google says I need to start by suggesting alternate solutions and talking about how my solution is the best one; however my instructors say that I should just stick to my solution. Anybody have an outline maybe?


texts:
If I use a PicoPSU, the computer is connected to an external 12V adapter (power brick) by a simple two pole +/- connector. The protective earth is not connected to the PC.

Does this situation involve any life-threatening risk in case of electric failure?

(Normally the computers are powered with standard ATX power supplies, which are connected to the power system by a three wire cable. One of the wires is the protective earth (PE) which is connected to all exposed metallic parts of the computer (case, backplate, audio jacks, etc.)


texts: Question on Ground/Neutral connection for a 220V equipment

texts: I sketched the following schematic from a motor controller board that has to be operated at 220V from L1 to L2. The earth wire is connected to the chassis of the machine. Where I live, it's common to see ground and neutral at the same point for 110V machines. My 220V connection has 3 wires: L1, L2, and neutral (not ground). That is, from L1/L2 to neutral I have 110V. So, my question about the schematic is: what if I connect the earth point of the motor controller to the neutral point of my 220V outlet? I would have 110V between L1/L2 and earth and that means the neutral would be attached to the chassis. In this case, as I do not have ground on my 220V outlet, should I disconnect the chassis from the neutral?


texts:
I stopped in the middle of debugging a very simple project where I send "hello world\r\n" every couple seconds out of USART2.  The first print hits the console and then I hang in an infinite loop after in startup_stm32.s:

/**
 * @brief  This is the code that gets called when the processor receives an
 *         unexpected interrupt.  This simply enters an infinite loop, preserving
 *         the system state for examination by a debugger.
 *
 * @param  None
 * @retval : None
*/
    .section .text.Default_Handler,"ax",%progbits
Default_Handler:
Infinite_Loop:
  b Infinite_Loop

I appear to not be handling an interrupt, but I myself actually have not enabled any interrupts.  I am only using the HAL_UART_* API (HAL_UART_Init, HAL_UART_Transmit, and implemented the HAL_UART_ErrorCallback).

How can I learn more about what interrupt isn't being handled?


texts: Proper insulation of wires connecting to the submersible pump (5V)

texts:
I'm building a simple plant watering station, which uses a relay-controlled submersible water pump (this one). The intent is to submerge the pump into a large enough water container to avoid frequent refills, but this means that the point where the pump's relatively short wires are extended will be submerged as well.

So here's the question: what is the correct way to insulate such joints? I'm currently using shrink tubing but I doubt it seals it well. Is there a better way?


texts: Interfacing with SD card in Graphics Display Designer (MicroChip)

texts: I have a PIC24 chip, a TFT screen, and a SD card reader/SD card. The software I'm using is MPLAB v8 and Graphics Display Designer addon. What I want to do is use Graphics Display Designer in MPLAB to display an image from the SD card onto the screen. I am able to read/write to the SD card, and I'm able to display stuff on the screen (using GDD). How can I display an image from the SD card onto the screen?


texts: I have one of these ancient Mentor game stations with the game tennis (Pong). Instead of using the controllers with a poti I'd like to use the Arduino PWM port to set a voltage between 0 and 5 Volt. However, this doesn't work, so there's no movement of the paddle. I tried several possibilities, but now wondering if the PWM and the poti are doing the same thing?


texts: capacitive touch film or integerated capacitive touch panel display? using under glass

texts:
We need to put display under 2mm glass. Our device must have capacitive touch input.
which method should we use? Capacitive Touch Films (place it under glass) or LCDs with integrated capacitive touch (place it exactly under glass)?
For Capacitive touch film i mean something like this:
http://www.buydisplay.com/default/3-2-inch-capacitive-touch-panel-wiith-controller-ft6236-for-240x320-dots


texts: sharing one 110VAC circuit with two high amperage devices

texts:
I have a fairly simple need and there may be a commercially available device that does this, but I have not found it.

I need to buy/make a 110VAC device that will automatically switch between two devices plugged into it. It would have one plug and two (or more) receptacles. Receptacle "A" would be by default "on". Receptacle "B" would only turn on by demand by the device that is plugged into it switching on which would automatically switch off receptacle "A" before switching "B" on.

This is to prevent overloading a single circuit and tripping a breaker or over loading the wiring.

Is there a name for this type of device? I have searched Google without success.
Are there commercial sources for it already built?
Is there a way to build one otherwise?

Thanks!


texts: MP3301 LED Driver RC Filter Calculation for PWM

texts:
I am looking at the datasheet for the MPS MP3301 Step-up LED Driver.  I have two questions about the "PWM Dimming" section on page 8.

The datasheet says for PWM frequencies > 1kHz, use an RC filter with a cut-off frequency equal to the PWM frequency / 10.  An example is then given for a PWM frequency of 20kHz where the RC filter uses a 20kΩ resistor and a 100nF capacitor.

Q1: How are the 20kΩ and 100nF values for the resistor and capacitor chosen?

[Edit: for a cut-off frequency of 2,000Hz, and a 100nF capacitor Fc = 1/2πRC seems to suggest a 820Ω resistor be used]

Second,

The "PWM Dimming" section also says the PWM voltage should be at least 1.5V, however at the bottom it says, "A DC voltage from 0.7V to 1.4V programs the output current from 0% to 100%."

Q2: Since PWM is used to control dimming, what use is changing the output current when using a PWM signal (i.e. why would we not just always use 1.5V+ for the PWM voltage)?


texts: For an inverting opamp, is inverting the same thing as an 180 degree phase shift?

texts:
Many texts talk about 180 degree phase shift as a function of the inverting opamp.

Is that correct? It seems to me inverting is happening almost immediately but phase is related to time and period and time delay between the input and output.


texts: I need to isolate my circuit from the power source of 5V dc. Since this is for medical use, and the device is powered by USB, the isolation needs to be at least 4kVrms, 5mm clearance, 8mm creapage distance. I searched for isolated DC-DC converters couldn't find any with those ratings and in small size. The remaining option I have, seems to be using 2 dc-dc converters in series. But that will be very inefficient and large in size. What could be the other ways to achieve this isolation?


texts: How to round all corners on a PCB in Altiium

texts:
All my PCB's have round corners, so you can't hurt yourself, and so it is easier to fit it into a rack.
Now with altium i always have drag the edges in the Board Shape Editor to make them round. I have to repeat this for each corner, and the "roundness" is always different for each corner. Is there a way to round every corner to the same amount/radius?

I've been working with altium for years now and i still haven't figured out this one thing. It always bugs me.


texts: Clip type for in-system programming (SOIC8 vs DIP8)

texts:
Updated:

What clip can I use to connect to this [specsheet] SPI flash chip in a DIP8 package?

note: this picture is of a motherboard that belongs to someone else, but mine has the same manufacturer, model-family, and Winbond 25Q64FVAIG. Only the third line (date code?) is different. The surrounding circuitry appears identical.

Original post:

I'm under the impression I can't use a SOIC8 clip to connect to a DIP8 package.

I'm seeing a large number of clips labelled both SOIC8 and DIP8 (1, 2) - one with a description saying "clip onto any 8 pin SOP, SOIC or DIP package."

What am I missing?


texts: I know I can take volts * amps to figure out watts, but what if the device accepts a range of volts? So if I have a device that takes 100-240 volts, and is 2 amps, what is the wattage being used? Does it change as different volts are use?


texts:
I have multiple users on seats (50), each with a small keypad for input. I need to collect inputs from all the users; I want to use Arduinos for each user, which will also display responses on a 7 segment display. I intend to connect all Arduinos using I2C but I fear the signal might drop due to long distance and fan-out limitations, so I'm considering daisy-chaining them.

Is this a good idea, or is there a better approach to do this?


texts: calculate output current caused by two sources

texts:
This is a common source degeneration with i1 and i2 are two current sources to model noise generated by the transistor and the resistor. In this video at 30:07 the professor calculated the current iout by some transfer functions from i1, i2 to iout. Can anyone explain the method here?
I understand the transfer function from i2 to iout but I don't get what he did to get transfer function from i1 to iout.
How can he calculate it that fast?


texts:
First of all, I know that this is not the best way to do this, even more so because I am using the LM358. I don t want extraordinary results.

Now, on the matter of the problem. I have attached the circuit. The only difference is that I mounted the 100nF Capacitor right at the input+ and GND of the op-amp.

The problem is that I get nothing as a result and if I remove the CAP I get a reading, but only for a few miliseconds, then it goes back to zero. What can I do?

The code is basically this, where the show() function is a function to display the number on an three digit led segment display.

 Input = analogRead(0);
 Input = map(Input, 0, 450, 25, 350);
 show(Input);


texts:
I'd like to understand this simple schematic to see if I get things clearly

If I understand things correctly:

when the switch is open, the current at the right black point is zero, the voltage is 12V.
when the switch is closed, the current at the right black point is 20 mA, the voltage is 0V

If this is correct, suppose now a similar schema with the following difference: between the switch and ground I have another 600 ohm resistor.

the potential at the black dot with the closed switch is now 6 V ?
any point along the horizontal connection between the T junction and the black dot are at the same potential. I guess they also enjoy the same current. If two points in a circuit experience the same potential and they are directly connected, do they always experience the same current as well ?


texts: Is my understanding of D-Flip Flop wrong?

texts:
So I am working on: http://www.nand2tetris.org/ and I am having a hard time understanding the D-Flip Flop, or maybe I should say, how Logism represents it.

I have this circuit and this is the current state I am in. The D Flip-Flop I have in my circuit has the property Trigger: Falling Edge.

Now I will click on load and in inputs:

And I will tick once

At this moment, it is ok that out = 0. I can understand it. However, my expectation is D should already be loaded, and should be showing 1, not 0.

Only after I tick one more time, I the D will be loaded:

If I cover the value shown by D, everything makes sense, how the Flip Flop works etc.. But as long as I am seeing the value in the D - Flip Flop itself, I get confused.

Is my understanding wrong or something wrong with Logisim?


texts: How fast will an op amp respond to changes in input voltage?

texts: What parameter would I be looking for in a datasheet (if such a parameter exists) if I want to determine how fast the op amp output responds to changes in input? I'm using an op amp as a difference amplifier to amplify the voltage across a current sense resistor. I'd like to know at least the order of the expected delay. This is for an error calculation. I'm directly sampling some voltage values, but the 'current values' are sampled only after it passes through a difference amplifier. So I'm guessing I won't be getting the value of current for the exact instance of the voltage if I sample both at the same time. Is there any such parameter specified?


texts: How to detect end of Capacitor Pre-charge

texts:
A common problem with batteries and loads connected to them is that the load often has substantial capacitors which needs managing .
When the battery is connected to the load by closing a Contactor/Relay a high inrush current flows to charge up the load capacitor. This current being in 100's of amps will damage the contactor/relay.
Below is a schematic which is supposed to precharge the capacitor C1 once the contactor is closed. As the voltage of C1 increases the PSU will turn on and its output will start rising.
Once the PSU output is high enough this feedback will turn the MOSFET T1 ON, to bypass the resistor RTH1.
This circuit does not work because a High load on the PSU will cause a voltage drop across RTH1 and this voltage drop will reset the PSU.
The PSU has a disable pin which can be used.
I am looking for a circuit which can detect that the capacitor is charged and trigger both the bypassing of RTH1 and enabling of the PSU.
I was considering a Window Comparator but have not figured out how to wire it up to detect the difference between the input voltage and C1 voltage.
Question:What type of circuit can be used to detect when C1 is charged?
(Voltage C1 ~=  Input Voltage 40-60V)
I am looking for either rough example, circuit name, type of device, etc.


texts: Avoiding node removal during optimization for preliminary estimation

texts:
I'm doing a preliminary FPGA design where I want to establish whether I will be able to implement the pinout and clock routing -- basically I'm placing all the hard IP blocks and wiring up the clocks, but I'd like to add as little other logic as I can get away with at the moment.
The optimizer now very aggressively removes a lot of logic due to the undefined signals, and associated clocks and hard IP as well, which makes life a bit more difficult.
In previous designs, I've simply routed undefined inputs and outputs to pins, which forced the optimizer to leave them in, but this time I'm out of pins already.
I'd possibly construct a massive shift register and connect that to some pins, that would likely tell the optimizer that the values of those signals are unknown but defined -- is there a better way to implement "placeholder" logic?
The goal right now would be to lock down a resource plan, which would allow board design to begin as soon as it is clear whether external clock routing and buffers are necessary and pinout is finalized.


texts: Charge/Discharge a Battery Pack Wired as a Segregated Paralleled Series

texts:
This is my first post on EE, so I'll try to be as simple but detailed as I can.

I have a 12S10P pack that I want to segregate into a 6S4P + 6S4P, 6S3P + 6S3P, 6S3P + 6S3P for "cautionary" LiIon balance charging. (My charger only goes up to 6S anyway..) I still want to draw power from all 6 at the same time in a 12S10P config.
I broke out MS Paint and unleashed my art skills to demonstrate the masterpiece. In this picture, imagine the top right cells are being balanced charged. There are no diodes in place. I don't know if balance charging will interfere with other cells in the pack (the ones in blue.) If there is unwanted adjacent charging, how do I stop that from happening? Ask questions if you need clarification.


texts:
I'm having a really hard time getting this RGB Led working with my arduino. First i'll describe my setup (schematic) , and then i'll show you the code I have.

I have 5 volts going into the second pin of the RGB LED , then I have 3 200 ohm resistors on each of the pins going out of the LED which respectively lead into PMW 9,10,11 of my arduino.

(The led setup)
pin 1 Red (-)
pin 2 Positive Voltage
pin 3 Blue (-)
pin 4 Green (-)

The code I have is

byte Red = 9;
byte Blu = 10;
byte Grn = 11;

void setup ()
{
 pinMode (Red, OUTPUT);
 pinMode (Blu, OUTPUT);
 pinMode (Grn, OUTPUT);
}

 int x=255;
 int y=0;
 int z=0;
 void loop ()
{
 analogWrite(Red,x);
 analogWrite(Blu,y);
 analogWrite(Grn,z);
}

The above code is supposed to produce a red light, but it produces a purple. I feel like it is something really simple.... Thanks


texts: How to calibrate the MLX90616 IR temperature sensor?

texts:
I have purchased some Melexis mlx90616 IR temperature sensors. The data sheet states that a calibration “by the customer” is required. By contacting my purchaser I got the answer: "The supplier has gotten back to us saying that they have limited resources available for technical support regarding the MLX90616".

It turns out that Melexis is not interested to offer support regarding the calibration procedure for the mlx90616 for those not buying high number of units.

Does anyone know how to calibrate the mlx90616, or at least the sequence of how to update the “read only” calibration coefficient registers? By having the information of how to, it would be an easy task to write the needed software.

Background info:

The returned object temperature readings (I2C/SMBus) are very slow changing and always close to the on-chip ambient temperature. Reading the raw IR channels shows rapid change when pointing to objects with different temperatures.

Reading the writable eeprom calibration coefficient register 0x2F returns 0x0020. The other eeprom read-only calibration registers (e.g. 0x26 to 0x2D) returns 0x00, which indicates that a calibration is needed. The equvialent regsisters on the comparable unit mlx90614, which is factory calibrated, is different from zero.

However, the procedure of how to calibrate the mlx90616 seems hard to find. There is no info in the datasheet regarding how to update the calibration registers, nor how to determine the values.


texts: Why location of CT is different for the two Circuit breakers in same substation layout?

texts:
This is a schematic diagram of a traction substation.
In this traction substation protection system schematic diagram, at point marked 'A', CT is located after the 25kV CB. However, at point marked 'B', CT is located before 25KV CB. Are there any benefits associated with this CT location? What problem can it create, if CT locations were interchanged (before CB instead of after it and vice versa).


texts: Ground Loop? Noise from 12v to 5v converter manifest in bluetooth audio source

texts:
I've created a custom, bluetooth audio harness for my Jeep WJ using off the shelf parts.

Amp - Clarion XC1410
Converter - 12v to 5v buck converter
Bluetooth Audio - Logitech Wireless Speaker Adapter

12v is supplied by the vehicle stereo harness in the dash. The amp and converter both connect to the 12v here. The converter supplies power to the BT adapter and the audio output from the adapter is connected to the amp. I have a constant alternator whine (vehicle on) in varying degrees when configured this way. Today I isolated some components to identify the source of the noise. While the converter is connected to an isolated power source the noise disappears. I would prefer to have the converter connected to a switched 12v power supply in the vehicle. Can anyone help me figure out why this is happening and how to address it?


texts: Most efficient way to PWM a boost converter

texts:
I am stepping up ~4V to 12V to power an LED strip with a boost-regulator.

I don't want to run the LED strips (3 leds in series with a resistor) at full brightness so I need to PWM them.

Is it better to PWM the output of the boost circuit before the LED strip with some sort of FET, or to PWM the enable signal to the switching regulator itself?


texts: Single microcontroller pin high-voltage piezo speaker driver, what are the pitfalls?

texts:
I just read this article, Microcontroller drives piezoelectric buzzer at high voltage through one pin, and it sounds too good to be true.

The schematic:

Q1 and Q3: BS250
Q2 and Q4: BSS295

This article was published in a well known journal, I guess it must be tested design. But somehow I wonder if there is a catch. So my actual questions are:

why is this circuit not so commonly mentioned on microcontroller forums? What is the catch with this design? Is this a really simple bridge load piezo speaker design that could be used for PWM driven audio amplifiers? Is there an amplifier class (eg class H) that this falls into? Is this too good to be true?


texts: I want to make a circuit with a 555 timer to run 72 LEDs all at the same time. I have already made a circuit, but am not sure If it will work safe and long or not. I am putting the picture of the circuit and I want anybody who can help to look at it and see if it needs some extra components. Please add them on the circuit or explain instructions to add.


texts: Does a 4-pin XLR cable actually contain 4 separate conductors? Alternatives?

texts:
Sounds like a dumb question but isn't, I think. While researching the possibility of using 4-pin XLR cables to hook together an LED stage lighting project, some catalogue pages seem to imply many 4-pin XLR cables (specifically, those used to carry power for video equipment) only contain 2 conductors.

Do any 4-pin XLR cables actually contain 4 separate conductors? How can I tell which are which?

Alternatively, can anyone suggest a readily available 4-conductor stage-proof cable/connector type? I need to transmit relatively high DC current (10A@5V) plus two signal wires (clock, data) over runs of 2-3m. I would much prefer buying cable assemblies off the shelf rather than making up my own as I need quite a few of them.


texts:
Is it possible to calculate maximum switching frequency of IGBT having only datasheet in hands?

https://www.semikron.com/dl/service-support/downloads/download/semikron-datasheet-skm200gal173d-22890495.pdf


texts: What is equivalent resistance equation in this case?

texts:
If we have three resistors (A, B & C) and we know that A is connected in parallel with B and also A is connected in series with C. How can we write the equation of the R equivalent of the three resistors in this case?.
Edit: I would like to highlight that this is not an actual electrical circuit. It is something related to measuring the electrical conductivity in rocks where the distribution of different rock types makes the first type (A) acts as a resistor in parallel with another rock type (B) and at the same time (A) is connected in series with a third rock type (C). Hereunder is a picture of what I mean.


texts:
Are there anyone can help me to give information about transistor DE 9926 and 9915? Could you like to share their datasheet ? I can not find their datasheet in every internet.

This is the transistor that I mean.


texts: Return current in a pcb stripline with floating plane

texts:
In a pcb stripline with ground reference planes above and below the signal trace, I understand that the return current will split between both planes and return to the supply.
What would happen if one of the planes was not connected to ground or anything else in the circuit (the plane is essentially floating)? Would there still be a return current in that plane?
If the curl of the magnetic field is equal to the current density J plus the displacement current, I think that the curl of the magnetic field must be non zero on the surface of the floating plane and there either an actual current or a displacement current must flow there (I say this as there should be a circulating magnetic field around the signal trace).
Is it possible for current to flow in the floating plane and return to the supply? Can this work like a capacitor where there is an open circuit but current still flows?


texts: NIMH Battery excedes charge limit when plugged into Tenergy Charger?

texts:
I recently purchased a NIMH Battery (5000MAH, 7.2V) and when I plugged it into my Tenergy Battery Charger I set the charge rate to 5amps. After watching it for several minutes the "voltage" jumped to around 8volts. Did I set it to the correct amps? Why did it exceed its apparent voltage limit?

Sorry, I'm still new to this, Thanks for the help!


texts: Maximum allowable voltage between PCB traces

texts:
I have some confusion regarding the guidelines for clearance between surface uncoated PCB traces (specifically component pads). IPC-2221 guidelines and other guidelines and standards indicate spacings that don't seem to make much sense.

I was intending to use a connector with 48V DC until I realized that it was rated for 30V maximum, on trying to figure out why this was I realized that the pads were at a 1.25mm pitch, which left less than 0.6mm between pads, thus violating the indications of IPC-2221. The connector pins themselves are spaced at 2.5mm leaving plenty of clearance otherwise.

These indications jump from 0.1mm for V<=30V to a minimum of 0.6mm for 30V < V < 150V (other standards indicate 0.4mm for V<50V, I have no access to EN 60664-1). Such jumps seem rather excessive.

I understand that air can withstand a field of 3kV/mm (i.e, 300V @ 0.1mm), so clearly this must be a surface contamination and creepage requirement more than a clearance requirement. Or perhaps it is also meant to take into account field increases due to 90° corners. But I even found a military test document that recommends as little as 0.13mm for 100V for altitudes of <3000ft.

I am pretty sure that many manufacturers go below the IPC recommendations (e.g., I am using a DC-DC converter rated for 60V input in a BGA package with a 1mm ball pitch and a maximum ball dimension of 0.7mm which leads to <0.3mm pcb spacing), the manufacturer does not even suggest using a sealer for the underside of the IC.

Besides subjecting the assembled board to (expensive) testing, is there any way to responsibly specify a smaller distance between traces?

Some related questions:

Low Voltage PCB Creepage Requirements (No answer)
Creepage distance over pcb
PCB track clearance (Conformal coating)


texts: Reset I2C slave chip when master goes away

texts:
I have a board with a transformer and a MCP23017. This board is connected to another board via 4 wires which bring over power (+5V, GND) and I2C bus for an ATmega328P acting as the master.

The ATmega will enable some pins on the MCP23017 when the user selects an input. The I2C pull-up are on the ATmega side.

Once a pin is enabled the MCP23017 will keep it enabled until reprogrammed or reset.
I want to reset the MCP23017 if the cable is disconnected, in order to switch off the pins, but I don't know how to detect it, given the fact that unplugging the cable is severing the I2C connection (and removing power from the ATmega).

The only solution that comes to my mind is to use a second uC to ping the main ATmega and remove biasing on the MCP23017 if the main board is not answering anymore, but I'd love to find a simpler solution.


texts: How to connect micro-USB to voltage regulator for MSP430 microcontroller?

texts:
I am going to use a micro-USB to power my MSP430 microcontroller. That means I only need the 5v and the GROUND pin. However, after discussing that the other pins should be untouched.. my friend said that was a bad idea. He said that I have to connect the D+ and D- to GND as well because I am not using them ? So my question is why should I connect them to GND ? and why should I use resistors to connect them to GND. Cant I just connect them to ground directly ? Shouldn't pins be named as NC here?

Here is a picture.


texts: A circuit or an i.c that will give a digital output high or low based on whether the input signal which is analog and is around 3.3V

texts: I need to check the performance of a DC/DC converter's output.The converter should give 3.3V   and does contain frequencies upto 8kHz in it(after using low pass filter).The bearable range for output voltage is 3.0V to 3.5V .Current from converter is very small around 40mamps. I need a circuit that will give a digital output high when the output voltage is not in this range.It should give a digital low when it is in  this range.


texts:
Given the blue transfer function graph, I want to design a circuit that can replicate the characteristics, preferably using an op amp. This is what I have done: where the red circuit is the red curve

So I just thought that the gain must be about 7, since that is the difference in dB. So using a non inverting amplifier I tried to correct the gain using the equation Gain=1+(R4/R3), and setting R3 to 3k ohms.

It became even more off and I am even more confused! Any help or examples appreciated.


texts: XBee Wi-Fi module connection directly to UART Sensor

texts:
I would like to connect a UART sensor directly to an XBee Wi-Fi module using its Rx-Tx, without using another MCU as an intermediate. The XBee would read the data from the sensor and send them via Wi-Fi to the internet (through a router).

Usual Application : Sensor -> MCU -> XBee -> Wi-Fi

My concept: Sensor-> Xbee -> Wi-Fi

From what I have read it is possible to sample analog sensors directly from XBee's analog inputs and send the data via Wi-Fi. It is also possible to sample the states of some GPIO pins of the XBee directly and send them. However, although the XBee has a UART, I have not found an application which uses this UART directly to communicate with a sensor. This UART is only used to communicate with an intermediate microcontroller which reads sensors, and sends commands to the XBee module via this UART. Another problem is that I should be able to transmit a UART command from the XBee module to the sensor (the sensor needs a command to send back a response). My purpose is to send periodically the read command to the sensor, get the response and transmit the response via Wi-Fi.

From my understanding it is not possible to use the UART of an XBee module like that, I would need an intermediate MCU. But I would like to ask, if I am missing something and this is possible. Has someone managed to do it or read something relevant? Is there a way to take advantage of the XBee's UART and program it to do this task?

Xbee: Digi XBee® Wi-Fi - OEM Module with Fully Integrated Support for Digi Remote Manager

Sensor: Dart Sensors WZ-EN CO module - Operation Manual


texts: Modelling the speed control of a mobile robotic system

texts:
I am attempting to model a robot and develop a PID based off of the paper at the bottom of this post before developing a physical model. However, the research paper appears to give parameters for wheel radius, a geared motor inertia and a tachometer constant but these are not included in the overall transfer function stated in the paper - unless these would be factored in by the parameters for equivalent damping / inertia?
Were I to include these parameters so to achieve a more realistic model how would that be done? The transfer function relates the speed of the robot to the voltage applied across the DC motor - so I presume this multiplied by the wheel radius can give the velocity of the wheels.
Any help/advice greatly appreciated.
Edit: Section of paper below


texts: Design considerations for micro dc to three phase ac AVR based (ESC) for miniature UAV applications

texts:
This is a huge question, I plan to present the problem in detail and my current plan of action for solving it. I'm hoping to get pointers on what to and not to do.

I was involved with a recent publication about HIL characterization of miniature uav actuators consisting of commercially available RC parts. Many conclusions were formed, but in short the weakest link in our actuator systems for our uavs are the motor controllers. They are all different and rather unpredictable. Some are sent ppm signals others like the ones on our rotary wing craft use i2c communication.

The ideal is to design a superior power system with n channel mosfets only.
The reason for this is a symmetrical phase control. However in order to do this it would require a slightly higher power source than the voltage being modulated to the motors.

To accomplish this I plan to use an external regulator for the MCU operating voltage and the higher mosfet driving voltage.

The next consideration is the mosfets them selves I plan to use multiple mosfets in parallel to reduce gate resistance and increase power capability.

I would like all the PCBs involved to be 2 layer PCBs to reduce production costs.
To do this and maintain a size small enough for miniature UAVs I plan to place the AVR based MCU on one board with molex wire to board connectors and programming connectors as well as status LEDs and support components.

Then all the power mosfets and optical isolation devices on another 2 layer PCB that connect to the MCU PCB with molex board to board interlock connectors.

The last consideration is the MCU its self.
I have no experience with programming embedded devices other than arduinos.
I also have less than nine weeks to produce this product.
Because of this I am considering using an atmega 328 and using the arduino boot loader and making all the pins compatible on the motor controller for initial ICP.

I like the xmega 16A but i do not want to rewrite the bootloader.

All this in mind there are considerations yet.
I will need to store externally and dynamically characterized parameters on the MCU for onboard control algorithms.

Thank you for your thoughts.

P.S. i2c will be the communication protocol to the motor controller because it is robust, bi directional and can support multiple devices on a single buss.


texts: Why are universal motors so commonly used?

texts: A quick look around my apartment shows a bunch of appliances powered by universal motors: drill, vacuum, blender, and probably several more. What makes the universal motor such a popular choice in small appliances? I'm guessing it has nothing to do with the ability to run on both AC and DC, since none of these devices work on DC and 120V batteries are rare.


texts:
Consider the circuit below:

simulate this circuit – Schematic created using CircuitLab

If I try to solve this circuit in the frequency domain, I get:

$$X_C = \frac{1}{\omega C} = \frac{1}{(120 \pi) (2.652)(10^{-3})}\approx1$$
$$X_L = \omega L = (120 \pi) (2.652)(10^{-3})\approx1$$

So, the equivalent impedance between A and B is:

$$Z_{eq} = \frac{(j)(-j)}{j-j} \approx \infty$$

Taking it into consideration, the current passing through AM1 is:

$$|I| = 0A$$

This seems reasonable, but if I simulate the same circuit in CircuitLab and check the current passing through AM1 I get:

(Please, click on the image)

As you can see, the current passing through AM1 is a DC current of 10A.

Why the current is not 0A and how can a linear circuit excited by an AC source generate a DC current of 10A? Since I remember, all signals in a linear circuit excited by sinusoidal sources must also be sinusoidal signals (steady state).

What am I missing here?

Thank you!


texts:
I would like to replace the bulb based tail/brake light and rear indicators/flashers on my bike with one integrated LED unit (flashers in brake light).

These are pretty expensive, and since I'm on a budget I'm looking at building one myself.

I've found some seemingly suitable 12v LEDs. I was hoping to use these to save me bothering with limiting resistors. However, one thing that bothers me is the max voltage rating of the LEDs and the rather unpredictable supply voltage. I've not yet measured it on my bike, but usually you would expect about 13v with the engine running. The absolute max voltage rating of the LEDs I'm looking at is 14v - do you think this is too close? Would the LEDs stand a higher voltage for short periods? (e.g. poss slightly higher V when at high engine revs when overtaking)

How would you protect against this? Would one resistor for the whole set of LEDs suffice? (one resistor supplying multiple parallel LEDs). Any suggestions on what kind of resistor to use? Perhaps it would just be better to use standard votage LEDs if I am forced to use resistors?

Anyway - any advice appreciated!


texts:
I'm developing a small robot using the STM32L152C Discovery board. I'm currently trying to configure the board using the STM32CubeMX. I've never worked at this very-low level (my experience is much more about algorithms), therefore I started doing simple things, like sending few characters to the UART port. The board doesn't have an external oscillator. Therefore I'm using the internal RC oscillator.

After doing this I wrote a very easy software that sends continuously a character to the UART port:

void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART2_UART_Init(void);

int main(void)
{
    HAL_Init();
    SystemClock_Config();
    MX_GPIO_Init();
    MX_USART2_UART_Init();
    unsigned char msg = '@';

    while (1)
    {
        HAL_UART_Transmit(&huart2,&msg,1,1);
    }
}

Using a 100 MHz oscilloscope this is what I get out of the pin:

The character that I'm sending is clearly visible, but it seems that the output is something like unstable. I've pressed the AUTO button on the scope many times, but nothing changes.

I thought that maybe it could be a problem with the RC oscillator. After setting the clock frequency to 4.194 MHz (the maximum) with the STM32 configurator, I've measured the clock but the output is not what I would expect.

This is what I get:

First I've noticed that the wave is not so "squared", and also the frequency is slightly different: 4.202 MHz instead of 4.194 MHz.

I would like to understand better why I get this output.

Concerning the shape, since the oscilloscope is 100 MHz and the clock has a frequency of ~4 MHz, I guess that the measuring tool is not the issue.
Concerning the frequency, I would say that the problem is in the accuracy of the RC oscillator itself. Can these be the cause of the problem I'm getting on the UART?


texts: How to wire a 5-leads single phase asynchronous motor to a 3-leads bidirectional controller?

texts:
Autistic has kindly identified the legacy motor I would like to recycle as a single phase asynchronous motor (see linked thread). Here is the internal schematic:

(source thread)

I would like to control it with a cheap wireless controller I had bought from Carymart; the issue is that it has only 3 outputs: UP, COMMON, DOWN, as seen on the following diagram.

(source)

I assume the phase shift capacitor is neither in the motor nor in the controller, but a bigger problem is how to wire the 5 leads motor to the 3 leads controller.

I have found this page on the manufacturer's website which is about this exactly, and implemented it in the following schematic, but they haven't said anything about the capacitor. It cannot be an electrolytic type because the current flows in both directions, and since current is always flowing in the capacitor when the motor is running and that it runs for more than 1s (that's a pool cover motor, probably 1min of operation every time), apparently it's not a good idea to have two electrolytics back to back. So I'm stuck.

Therefore I need either a new arrangement, or a type of suitable capacitor. Please advise :)

simulate this circuit – Schematic created using CircuitLab


texts:
I am designing a four layer PCB, (signal, ground, pwr, signal), which is to generate +-1V max 30kHz frequency signals which is output on a differential pair.
It is pretty simple board layout but I am little confused about whether I should use a split ground or even slit the board. My board layout can be seen below.

There seems to be alot of debate over the benefits or possible problems of what a split ground might do. My plan for the board is to have the left half dedicated to the output signals, powered by two regulators +3.3V and -3.3V. I have a 2MHz clock that generates the clock for frequency generating chips, AD9106 x2. I am worried about this potentially contaminating the analog signals.
Additionally I have placed ferrite beads (MPZ1608B471A) on the output of each of the regulators to stop this, I have employed good decoupling capacitors where required.

Any hints or tips on what grounding scheme may be best would be appreciated.


texts: What does the Vref pin do on the A5973D?

texts:
I'm thinking about using this switching regulator A5973D.

The data sheet is here:
http://www.st.com/content/ccc/resource/technical/document/datasheet/98/04/af/4b/8c/a3/42/cc/CD00172501.pdf/files/CD00172501.pdf/jcr:content/translations/en.CD00172501.pdf

Does the Vref pin provide 3v3 or does it need to be connected to an external 3v3 supply?

My application includes a 3v3 MCU circuit and three A5973D circuits, one set to 3v3, one 5v and one 12v. What should I do with the Vref pins on each IC?


texts: Using a vintage button bulb saver be used for CFL or halogen lamps?

texts:
Recently got a big box full of vintage tools and electrical stuffs. I came across this strange looking (seems vintage by its looks) button device. Its the first time I came across it.I googled and read that it can be of two types thermistor and diode type. The later actually uses one half of cycle to increase filament life.

So, will it do any good with other forms of lamps like halogen, CFL etc? I'm just curious, thats all:) Also does the button need to be installed in a particular direction?


texts: How can I debug the amplifier section of tuxgraphic's powersupply?

texts:
I've built this circuit: http://www.tuxgraphics.org/common/images2/article379/powersupply.gif

Here is a closeup of the amplifier section which I've built:

simulate this circuit – Schematic created using CircuitLab

And in the instructions here http://www.tuxgraphics.org/electronics/200506/article379.shtml Guido suggests a testing routine:

Test1: Connect some powersupply (at least 15V) to the power input of the circuit and check that you get 5V DC behind the voltage regulator.
Test2: Measure the output voltage. It should be 0V.
Test3: Connect pin 7 and pin 26 on the microcontroller with a wire (no microcontroller in the socket). You should get on the output a couple of volts less than what is used at DC input. Remove the wire and the output should go back to zero. Be sure to not cause any short circuit on the output.

I'm stuck on Test3. I get 0 volts output when I connect pin 7 (Vcc) to pin 26 (end of DAC output). I've quadruple checked all transistors and matched their pinouts and orientations. I've tried replacing a couple of them incase thats the problem. However, now I'm trying to understand a little theory to understand how to debug it with a multimeter. What voltage drops could I measure to find where the problem is? I can probably gain access to an oscilloscope of that would help, however I am dealing with fixed DC voltages so I would think a multimeter would be enough.


texts: What does pulldown resistor from Arduino's output pin to ground do? Is it necessary?

texts:
I came across the first picture below. But I am not able to find out how such arrangement is necessary or beneficial when you want to switch a load with an N channel MOSFET?

Question number 1: Is there any advantages or disadvantages associated with the first and second type? Assuming that the MOSFET is saturated at 3 volts?

I found the text below, where I found the first picture:

  This circuit is pretty simple. The only part that looks funny is the
  resistor. This is a pull-down resistor. The resistor holds the gate
  low when the arduino does not send a high signal. This is here incase
  the arduino comes loose, or the wiring is bad it will default to off.
  You don’t want this pin to ever be floating as it will trigger on and
  off.

Question number 2: I don't understand how the first resistor not being present, can cause any problem? (like the second picture, without any connection from output pin to the GND)

Question number 3: In case that you think the first resistor is adding robustness to the circuit, don't you think still the inclusion of the 2nd resistor is also beneficial?! Because each Arduino's pin can only output 40 mA.

Thank you very much in advance.


texts: Current Transformer Analysis giving error

texts:
So i have tested about 10 CTs in a transformer using Omicron CT-Analyzer and except for one CT, every result came fine.

As i am still in my learning phase, i am not sure why these two parameters failed when everything else is fine (Excitation curve, Current Ratio, VA Burden etc, every thing is fine).
Please help me understand as to why these failed. You can refer to the pdf of the full CT test report, can be downloaded from this link (https://tssd.egnyte.com/dl/GUBWoVLOD3).
Thank you and looking forward to hearing for the possible solutions.


texts:
I need help with the following problem:

Given symmetric three phase system (see attachment) of phase voltages with angular frequency ω=100rad/s, R=5ωL=100Ω. Find capacitance of capacitor C such that the power factor of three phase receiver has maximum value.

After transformation of Y capacitors to Δ (see attachment), it gives $$C_1=C/3.$$

Now we have a Δ connection of impedance Z which is a parallel of R,j5ωL and C1. Let $$\underline{Z_1}=R+j5\omega L.$$ From given data we can find that L=0.2H. This gives $$\underline{Z_1}=100(1+j)\Omega.$$ Now

$$\underline{Z}=\frac{\underline{Z_1}\cdot(-jX_{C_1})}{\underline{Z_1}+(-jX_{C_1})}=\frac{300(3+j(3−2⋅10^4C))}{2⋅10^8C^2−6⋅10^4C+9}\Omega
$$

Now we have a three phase system with receiver in Δ connection (see attachment):

After Δ to Y transformation (see attachment), we get new impedance:
$$\underline{Z_2}=\frac{\underline{Z}}{3}=\frac{100(3+j(3−2⋅10^4C))}{2⋅10^8C^2−6⋅10^4C+9}\Omega.$$

Let

$$\underline{Z_3}=\underline{Z_2}+jX_L=\underline{Z_2}+j20=\frac{20(15+j8(3−2⋅10^4C+25⋅10^6C^2))}{2⋅10^8C^2−6⋅10^4C+9}\Omega.$$
Now we have a clean Y receiver connection with impedance Z3 (see attachment):

Question: We are not given any values for voltage, current or power, so how to express power factor cosϕ without knowing any of those values?

EDIT:
Power factor can be expressed by $$\cos\phi=\frac{\mathfrak{R}(\underline{S})}{\sqrt{P^2+Q^2}}$$ where $$\underline{S}$$ is complex apparent power, P is active and Q is reactive power. Power factor has a maximum value when reactive power tends to zero. Since we know only the impedance, we can look at the imaginary part of impedance Z3. If we introduce a function $$f(C)=\frac{160(25\cdot 10^6C^2-2\cdot 10^4C+3)}{2⋅10^8C^2−6⋅10^4C+9}$$, minimum value of f(C) is $$\frac{-40}{3}$$ at $$C=3\cdot 10^{-4}F.$$ So, maximum power factor is for C=0.0003F.

Question: Is this correct?


texts: Program not running on STM32F4 after disconnect it from PC

texts:
I developed a program on STM32F4 using keil uV on windows 10, it works perfectly when the target is powered by the computer even after i stop the debugging.
Normally after downloading the program in the flash memory it will run automatically when the target became powered by any source of energy.
I can't figure why it doesn't work in my case.


texts:
This question is more to understand why it hasn't work for me, this is the case:
I have an old Kindle 2nd generation e-reader, the batteries are almost depleted, working just a few minutes. So I have this other batteries, from a phone, same voltage a little more mah, 1530mAh vs 1500. The size was almost the same, so it seems to me that it was worth the try. Removed the kindle's battery little board and connected the battery cell to it, but it didn't work, so I wanted to know why.
Thanks.


texts: Is ground connection in home electrical system really necessary?

texts:
I know that the answer to my question is "Yes, it is!". The ground connection is needed to avoid a person touching a metallic part of faulty equipment to be electrically shocked. So the person acts as the conductor closing the circuit between the high voltage metallic part and the ground (at zero volt by definition). The grounding connection hence offers an alternative path for the current to flow, and this happens because somewhere along the power distribution system, the neutral wire N is connected to a metallic rod planted into the ground.
My question is: what if this neutral wire - ground connection is removed, as illustrated in the picture? This would make the ground wire in home electric sockets unnecessary, since a person touching the metallic case of a faulty equipment doesn't close the circuit, because there is not the circuit including the ground. So, as I understand it, this would work (maybe) if the power distribution system is not grounded anywhere. Is this possible to realize a totally floating-from-ground power distribution system? I am pretty sure the answer is no, but I don't know why... so, why is not possible???
Thank you.


texts: "light_ws2812" library 10x slower than required (AVR C, ATMega328p int. 8Mhz)

texts:
So I'm trying to run some SK6812 (WS2812 clones) on a standalone ATMega328p.

The output signal is too slow! I define F_CPU as 8000000 (8Mhz), both in the code and in the Atmel Studio Symbols, but my signal is slow by a factor of 10. The LED is always white, instead of red as the code intends.

#ifndef F_CPU
#define F_CPU 8000000UL // 8 MHz clock speed
#endif

#include <util/delay.h>
#include <avr/io.h>
#include <avr/interrupt.h>

#include "light_ws2812.h"

struct cRGB led[1];

int main(void)
{

    while(1)
    {
        led[0].r=25;led[0].g=00;led[0].b=0;    // Write red to array
        ws2812_setleds(led,1);
        _delay_ms(500);                         // wait for 500ms.

        //led[0].r=0;led[0].g=25;led[0].b=0;            // green
        //ws2812_setleds(led,1);
        //_delay_ms(500);

        //led[0].r=0;led[0].g=00;led[0].b=25;       // blue
        //ws2812_setleds(led,1);
        //_delay_ms(500);
    }
}

Fuses are l:0xA2, h:0xD9, e:0x07. This should correspond to an internal 8Mhz clock (verified on B0 with oscilloscope). Here's what I get for a data signal on B4:

The data looks fine (00000000 for green, then 00011001 (25d) for red). However the period is about 12µs, but according to the SK6812 datasheet, the period must be 1.25µs ± 150ns:

There's not much to show on the schematic, but to be thorough:

And like I said before, the intended header for data (D6) didn't output anything, so I had to use B4 since it was also broken out to a header.(Connectivity issue, I figured it out)

Any help is appreciated!


texts: I2C not working unless its through a mosfet (not level shifting)

texts:
Ive been dipping my toes into the world of hardware over the last year and I'm working on a project that i've been stumped on for a few months now. I've made progress on alot of roadblocks but this one has me stumped.

I learned about the DDC protocol that computer monitors use to allow software to control certain aspects of a monitors setting (Input, brightness, color settings etc). Its just I2C. Heres the wiki page for it. https://en.wikipedia.org/wiki/Display_Data_Channel

Essentially pin number 15, 16 on an HDMI port serve as SCL and SDL respectively.

using the linux package ddccontrol, i was able to change the monitor source input from HDMI to DP. This answer provides some context: https://askubuntu.com/questions/860761/ubuntu-command-line-to-change-input-source-on-a-display-monitor

Running the package in debug mode I was able to extract the payload being sent across i2C. Using a logic analyzer I was able to confirm the payload as well get the address it was writing too.

So I wrote an arduino sketch to see If I could replicate this. I put it on an arduino uno and BOOM, it worked!

Now I wanted to port this over to an ESP8266 micro controller. Minor changes to the arduino sketch and it was ported over. However there was a whole heap of weird behavior. The logic analyzer showed things looping and no ACKs from the slave. After some research I realized theres two main differences between the esp and the arduino

1) esp achieves i2c through bit banging instead of dedicated hardware

2) esp is 3.3v device and Arduino is 5v

I realized the HDMI protocol defines the voltage at 5v so I bought a logic level converted to test with(https://www.amazon.com/gp/product/B07YZTW2SM/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1)

I plugged it all in, adding pull up resistors to both sides of the converted signal. and...

IT WORKED....

However i had made a mistake. I forgot to connect the 5v power source into the HV side of the logic lever converted. So it wasnt even converting the signal... why did this work???

I confirmed that without the 5v side connected, the logic level converter wasnt converting anything at all. 3.3v on both sides. I plugged in the 5v side and to my surprise, no ACK from the monitor....

Im pretty stumped here. I thought for sure the monitor just required 5v logic levels...

What im assuming is maybe the mosfets are cleaning up the signal somehow? Anyone have any idea on what happened here? I'm happy I have a working prototype but I'd like to know what exactly its doing.


texts: What could be used to send induced/coupled CAN-BUS signal

texts:
My problem I am experiencing is with the circuitry or IC combination to follow. I don't need a answer of what exact IC models I need, as that would be plain stupid. What I asked originally about the op-amp was because I believe it was the correct thing to use if my signal that is induced does not inherit the same peaks of voltage in the original wave form.
My hypothesis of how the circuit should work is that when the signal from CAN_H or CAN_L is induced into sperate strips -> the signal is then rectified to the correct wave form depending on what gets distorted then -> using an IC (comparator as suggested by Andy, also after examining graphs an other data ) to ensure the correct digital form (if an analog form generates in the previous stage) and then sending it to an external monitoring system.  All without physical obstruction of any lines. Is this thinking correct.
What I want from the circuit is that when I connect it over CAN lines using small copper pads on a PCB it then needs to send this (image) out after reading to an external monitoring system .

I cannot use the standard methods of connecting to the J1939 connector on the heavy duty vehicles as it becomes an issue of space and tampering/fiddling by drivers.

My issue only lies with the overall circuit choice. As Andy aka has pointed out what he has done and that this can be done. I only need to be able to reproduce those signals. Hence the link to this.

I am sorry to have explained my question vaguely, it generally sounds better in ones' head before they speak or write.


texts: Using a diode to protect a voltage regulator

texts:
I am trying to power an ESP32 devboard from 12 V. My first attempt was to directly connect the 12 V to the 5 V connection, because the ESP32 devboard employs an 1117 3.3 V voltage regulator anyway, but I missed that the CP2102 used on the devboard is directly connected to the 5 V, which causes it to heat up and eventually kill the CP2102. Hence I'd like to use an external 1117 (or something alike) to get an additional 3.3 V that I can connect to the 3.3 V connection of the devboard.
My current issue is protecting the external 1117, because I assume that it might take damage when connecting the devboard to USB for programming, because in this case the 3.3 V connection would get 3.3 V from the internal 1117 and I read that those voltage regulators are sensitive to a positive voltage applied at the output terminal.

simulate this circuit – Schematic created using CircuitLab
The simplest solution would be using a super bridge or switch to disconnect the output of the external 1117 when using USB, but this would be prone to errors, eventually causing the voltage regulator being destroyed, because someone forgot to pull off that jumper or switch the switch. Hence I thought about using a diode for protecting the output of the voltage regulator:

simulate this circuit
anyway, due to the forward voltage I will "lose" some of the 3.3 V I'm generating, which might be crucial because I'm using PWM from some of the pins and with 3.3 V I'm already at the lower end of the specs of the fans I'm controlling. From a quick research I saw that a typical Schottky has a Vf of about 400-500 mV and this would be the voltage drop to expect, am I right? Are there diodes with an even lower voltage drop? Would using a 5 V voltage regulator along with a diode with a Vf of 1.3 V a viable option? Or would it be too much of a problem that the Vf is temperature- and current-dependent?
This question seems to address the issue but I fail to see, how the diode would protect the 1117 if nothing is connected to the input. Other than that I did not find any other questions that address the topic. Most circuit protection issues are about reverse polarity.


texts:
Hello.
I hope this is not too novice question. IKEA got stuck with piles of garden solar lighting (their product no 21777) which they sold for 1€ each.

Looking at the back (large solar panel, 2000 mAh NiMH battery, switch etc.) I took seven home (I wish I had taken 20...). I Took one apart to play with it and found a 3-LED block which gets 1.2 V and produces very strong light. What am I missing?

The block does not appear to have any electronics on it apart of the three parallel LEDs. How does the LED work on 1.2 V?

Hello again. I think that SamGibson's answer (with the Scope wave pic) is the right one. The battery is normal size as can be seen in the pic (it also say on it HR6/AA) and the module does not have any electronics on it. BUT the 1.2V DC I measured seem to be wrong (I use basic digital multimeter). as an experiment, I decided to connect the module outside, directly to the battery poles. Nothing !!   but when I connected to the circuit it works fine. Changing the setting on the multimenter to AC shows 2.5V. As it is a basic multimeter, I assume that this is also very not accurate, but the the basic experiment shows that there is some sort of boosting circuit on the main board to drive those leds. (Now I just need to figure out why this does not drive my 5mm, flashing blue, LED...)
Many thanks to all that help and contributed.
All the best.


texts: Why are one channel's transistors in a power amp getting much hotter than the other's?

texts:
(Context: I don't have a background in e.e., but getting better at basic bench work.) I'm repairing/recapping an early 70s German integrated stereo. The power amp output section has four large heatsinks for its transistors, two each corresponding to the left and right stereo channels. After a very short period of time, even a couple minutes, the left-channel's sinks become extremely hot to the touch while the right channel remains cold.

The audio output is correct and expected, a typical radio or aux music signal amplified in stereo. Sound on both channels is totally fine coming out of the speakers. I only noticed the heating asymmetry by accident.

I don't know that this is a problem that needs solving, exactly, but the heat in that area seems likely to reduce the life of the new left channel caps somewhat.

I'd like to understand if (1) this indicates a problem and (2) what might explain it? Could those power transistors be deteriorating unevenly with age? Could something else that feeds them be behaving strangely? (I've replaced all the electrolytics and a couple questionable looking film caps on this board, for what that's worth.)

Any insight or theories/pointers/assistance very welcome. I have a bench oscilloscope and can probe signals in an entry level kind of way if that's useful but not sure what I'd be looking for in this case since output seems fine.

Worth noting that the differential in heat remains over long durations-- the right channel does eventually (an hour?) become perceivably a bit warm to the touch, but the left channel becomes scorching very quickly and stays that way. (This is also true if the left speaker is not even plugged in, fwiw)

Photo of the board and image of the schematic for this board below. The left channel is the left half of the board, and the two left heat sink sections.

Schematic. Input from preamp at left, output to speakers at right. Left channel is top half of the diagram. T708 (and maybe T709? maybe T705?) appear to be the very hot transistors.


texts: Different time constants for charging and discharging of a circuit with a constant current source and a capacitor

texts: Consider a circuit that only has a constant current source and a capacitor. The voltage across a capacitor is proportional to the integral of the current I, times time. Since the current is constant it may be taken outside the integral. Based on this, the voltage across the capacitor will continue to increase as time goes by. Now let's say I turn the source on for X seconds and then turn it off. Would the time constant for the charging phase, and the time constant for the discharging phase be the same? I'm not sure if the input resistance of the source has any effect on the time constant. Thank you for any advice!