texts:
I need to find something like this but that is automatable, over I2C or GPIB or something.
Is there a name for this? I am having problems finding something. Worst case I can buy this and hook up a motor to it, but I imagine a cheap packaged solution already exists, I just don't know the name for it.
Looking for these specs:
7Vrms (so ~20W at the low end of 3ohm, <1W above 50ohm)
3ohm-100ohm in ~20 log spaced steps
Automatable
A decade box could also work if it were automatable. They seem to be very expensive ($6k) for both automatable and specced for power.
The specific application is for loading a sigma delta (Class D) op amp (an audio amplifier). The output is differential and switching, a 1kHz AC sine wave is the resulting waveform after low pass filtering. A constant DC current sink will not fit the bill unfortunately. Open to other solutions though!


texts:
I've been doing a lot with Arduino recently. It's very simple because you can directly execute C++ code on it without the need of operating systems or drivers.

I've done some research and AFAIK, you usually install Linux on the Raspberry PI and create python scripts or C++ binaries on it.

Question: Is it possible to run code on it without any operating system, but still being able to use HDMI and SD cards?


texts: High quality IR projector for depth detection

texts:
I want to build my own depth sensor like the way Kinect does it, using IR and a Camera but I can't find anywhere where I can get the "IR Camera". I do not need a CMOS board as I will be computing everything on a computer instead of a "middleware". What companies/brands sell them? Also can you provide a link or something, so I can research?

Every time I check out Infrared Lights, all I generally find is infrared LEDs, but nothing about the receivers...


texts: Why are(n't) rechargeable batteries damaged by partial charging?

texts:
Over the years, I've come across websites and people with different opinions on the "correct" way to charge rechargeable batteries (I'm more concerned with laptop, tablet and phone batteries than with rechargeable AA or AAA batteries, if that makes a difference).

Some (e.g. this one and some of my family members) claim that one should discharge all the way to 0% (or close to that) and charge all the way to 100% to prevent the battery from developing a "memory" (whatever that means; do they mean hysteresis?) and losing charge-storing capacity.
Others (mainly Apple representatives and some of my family members) claim this was the case with older batteries only and newer batteries are "smarter" (whatever that means) than that and it's battery cycles that count now.
Still others (e.g. this one, this one and this one) claim that the best way to charge a battery is to let it oscillate only between X% and Y% (with different values of X and Y depending on whom you ask, but all agree that X>0 and Y<100) because that somehow increases battery life by preventing overloading (no mention of what the lower limit is for).

None of those websites or people have ever explained why what they say is true is, in fact, true, so I thought I'd ask here.

I'm aware of how battery cycles work:

I'm also aware that battery life/health decreases over time and it's just a process that can't be helped because entropy.

My own experience with battery charging and health is varied (and I haven't performed nearly enough experiments to come up with a reasonable conclusion because I only have so much money to spend on electronics and so much time to spend draining and recharging batteries):

My laptop (which is from mid-2014) spends most of its time permanently plugged in and at 100% battery. If I ask it what its health is, it says it's at 82% health, it's completed 609 cycles and its actual charge is 96%... which probably means health is not a linear measure of the scaling of the 0%–100% range as it goes down compared to the original 0%–100% range, but some more complicated quantity. When I do unplug it, the battery lasts a good while (haven't measured it and certainly haven't compared it to what it originally lasted).
My old phone (an iPhone 6, so it's as old as whenever that came out, which is more recent than 2014) was charged whenever I thought the battery level was lower than I wanted it to be and I knew I wouldn't be able to charge it for several hours, and it often (but not always) got all the way to 100% and then remained plugged in for hours. If I ask it about its battery health, it says the maximum capacity is 73% and "[the] battery is signicantly degraded". The battery now lasts very little and drains very quickly; the phone will turn off (and claim it's run out of battery) when the indicator is anywhere from 1% to 53% — but this may be due to either age or charging habits, so it's inconclusive without more evidence.
I can figure out the battery healths and explain the charging habits of my old tablet and my wife's tablet phones if necessary.

I'd like to settle this once and for all, please, preferably with an answer that includes physics. What's the best way to charge a battery, and why is that that best way?


texts: Switching a circuit from a 2 wire dc motor to 3 wire motor

texts:
I am an extreme newbie (having done software all my life, hardware is making me feel super dumb), and big picture is I am trying to replicate this work:

http://words.iame.li/post/112091812552/buttonpusher

Although he seems to be taking some shortcuts which I don't quite understand (where does the yellow and green wire go on the pi? How does he join the green wire up to the power supply?)

As part of my learning, I decided to do it by steps on an established kit. I have just completed this circuit:

As you can see from that rather complicated chart (which i assume is for protecting the RaspPi) the motor is ultimately powered by two wires, positive and negative.

I now want to take this setup, WHICH WORKS!, and apply it to the Futaba servo which he uses (https://www.amazon.com/Futaba-FUTM0031-S3003-Standard-Servo/dp/B0015H2V72) but simply plugging in my wires to the red and black receptors of the Futaba servo didnt work, presumably because I need a neutral wire to ground the new white wire from the Futaba? I must be sounding so retarded now to you guys, but I appreciate any and all tips as to fundamental concepts i must go and learn and terms and things i need to google. Please help!


texts: Instead of a battery, can I connect this light to a DC power supply?

texts:
I bought this LED video light recently, which to my surprise doesn't have a DC power / wall wart input to connect it to mains power. Instead, you're required to use a 7.4V Sony 970 series camera battery:

Needless to say, I don't have the correct battery and don't want to shell out for one. However, I have a decent bench PSU - can I simply dial it to 7.4V and connect it (using croc clips or the like) to the battery power terminals on the light? If not, what circuit/modifications would I need to make?

[UPDATE 20/10/2017] - Okay, I took the plunge and connected it up. The light functions for a second or two, and then the low battery indicator comes and and the light shut off. If I toggle the power on the PSU the same thing happens - light comes on for a moment, then shuts down due to (presumably) a low-battery shutoff feature. Any good ideas on how to get around this?


texts: How do LTE radio networks deal with co-channel interference?

texts:
In 802.11 Wifi, I've read that a wifi adapter (like my laptop's wifi adapter/radio) will use Energy Detection to see if a channel is busy (if a certain energy threshold is detected on the channel, it won't try to use the channel itself). Then there is also Virtual Carrier Sensing, where the wifi adapter will look for Network Allocation Vector timers to see if the channel is free to use.

Do LTE devices like my cellphone use anything like the above?


texts: install AUX input on car audio/navi system

texts:
I want to install an AUX connection on my car navigation system. I have never done such thing before, though. I searched a bit around and a very similar installation to what I need is here on Saabworld.net. However, I don't have that cassette player but a navigation system, so the board looks different. I haven't really played around yet but I thought I'd ask some more experienced people if they see from the pictures of the board and/or the connectors whether it is obvious where to soldier the AUX input connection.

If not obvious, maybe you could give me helpful tips what I would have to look at or where/how to get the necessary information.

Edit: Thanks to a hint, the head unit might not have any audio signals at all on the board. From here you can see that the main unit is in the back of the car. Edit: From other sources, I have read that it is possible to install a telephone headset. This must be somewhere in the front of the car. Some more information about the telephone input is here. Some more about the audio system in general (but which mostly just confuses me) is here.

The communication between the different parts is via the (I)-can protocol. There is the Saablin project - a small Linux - which has reversed engineered the protocol and enables usages such as to install a line-in (by emulating the CD changer). For example, see here. A similar project is an Arduino project here. However, that might be overkill for me.

About the main unit:

It is a Kenwood KNA-DV2200/S.

I only have pictures from the outside yet as I haven't yet uninstalled and opened it. However, these pictures are already interesting. You have two cinch connectors there which look very much like a line audio input. There is also some not-connected plug with 5 pins (or so). Maybe that is for telephone and it would enable the cinch audio input somehow?

About the head unit board:

What is that CN5 connector on the board which is not plugged?

Or, from the input adapters here or here, I'm not sure whether they might already fit to some of the connectors. (It says there that it is for Saab 93/95 from 2006-2009, but mine is a Saab 95 from 2004, so not sure if it is compatible.)

Or, what is that yellow cinch plug on the back? Edit: That is video input as it says on the back of the board.

Or, is the whole unit just digital and the digital-analog conversion is done somewhere else in an external amplifier? I think that 6-pin plug is the output. I'm not sure if that is something digital or analog.

What are (or might be) the connectors ACC, PARK, ILL, ILL-CONT, BU, REMO?

Some of the chips on the board:

NEC D703033AGC. Probably this microcontroler.
78DL05F. This (Semiconductor) or this (Low Drop output Voltage Regulator).
7611C. Not sure which one. Maybe an amplifier? The whole section of the board seems all radio related (multiple coils and capacitors - I added a picture of that). Or maybe this one (Bipolar IC For Switching Power Supply Control).


texts:
I have a chip-on-board LED that requires 36V max, 300 mA, but I have a power supply designed for a 12V max, 900 mA LED.  The power supply is a pretty standard constant current power supply that outputs 900 mA for the LED and adjusts the voltage as required.
Is there a simple way to take this output and convert it from 900 mA to 300 mA without disrupting the constant current power supply's regulation?  I am aware things like buck converters exist but I am unsure if they will function properly in this instance.
Link to the LED in question
The power supply is part of a larger unit and cannot be replaced.  Solutions that only supply partial power to the LED (at least 5W) would be acceptable.
Update: I dug the old power supply out of the unit and discovered it is capable of 16V max at 16W max.  It supplies 1A at 10.06V to a LED currently.
Link to the power supply currently used (Model: RLDD015L-1000)


texts:
I've been trying to understand the astable multivibrator shown above. Wikipedia has a pretty good description. But I've tried to write it up on my blog in my own words here: http://41j.com/blog/2014/12/astable-multivibrator-oscillator/

I'm uncertain about the following things:

R1 and R4 are low value resistors, am I right in thinking they just limit the current going into the transistors? Do they have any other purpose?

The way I understand the process, at startup one of Q1 or Q2 will be conducting (or will randomly start conducting first?). That will allow it's capacitor to charge up (because current will be flowing past it). This drives the capacitors other terminal negative, forcing the other transistor open.

The negative terminal of the capacitor slowly discharges (is my terminology correct?) though the larger resistor (R3 or R2). As the negative terminal becomes positive it no longer holds the other transistor open, allowing the other capacitor to charge up and the process to start again with the other transistor.

Is there anything fundamental missing in my understanding?


texts: Multisim opamp output oscillates for DC volt if it reaches saturation

texts:
Am trying to learn op-amps using Multisim. In the simulation I set initial condition to zero and set the circuit so the output reaches saturation point but instead its ringing with frequency 374HZ. I don't understand is this how the simulators indicates an error or is my calculation for the output voltage wrong

\$\ V_{3}= 4 - 4e^{500t}\$


texts: Do wires need to share similar characteristics in order for crosstalk to occur?

texts: My understanding of crosstalk is how a radio transceiver works. You basically tune your transmitter and receiver to a similar frequency in order to get a cross-coupling of energy (the transmitter's energy gets coupling over to the receiver, hence the receiver is able to listen to what is being broadcasted). Is this analogous true for crosstalk in parallel unshielded, untwisted wires where the 2 wires have similar inductance and capacitance?


texts: Output impedance function generator, limiting the current

texts:
I've the following schematic:

simulate this circuit – Schematic created using CircuitLab

Now the R of 50 ohm does limit the current that be supplied to the load. Is there a way to be independend of the 50 ohm resistor? I thought about a voltage buffer after the function generator?!


texts: is there a solderless solution for component with pins 1.70mm apart?

texts:
I have a CAT4101 http://www.onsemi.com/pub_link/Collateral/CAT4101-D.PDF constant current LED driver which has 5 pins at 1.70 mm BSC apart.

As I am a newbie I would prefer to use only a solderless breadboard, however standard these have pin distances of 2.54mm.

My entire prototype will be deployed on a solderless breadboard so I would like to find a solution to use the CAT4101.

I would like to avoid having to solder 5 wires directly onto the pins as these are so close and I am not really sure how well I can get this job done. Soldering the component on some other type of prototyping board would already be easier and then I could get the wires from the board to connect with the breadboard. But I am not really sure what's available out there

Any suggestions?


texts: How to implement simple stack switching in PIC12/16 cores?

texts:
I am trying to understand how real time operating systems work. I have looked at the source codes of some RTOSes. I want to learn by creating my simple RTOS, something like FLIRT.

I am using PIC16 series and XC8 C compiler with MPLABX. I also want to implement this very simple RTOS to PIC12 series.

So, I decided that I should start by learning how to manipulate stack (like supercat did in this answer) and I started searching and came across AN818 which is titled "Manipulating the Stack of the PIC18 Microcontroller". Cited from the application note:

  Traditionally, the microcontroller stack has only been
  used as a storage space for return addresses of subroutines
  or interrupt routines, where all ‘push’ and ‘pop’
  operations were hidden.

  For the most part, users had
  no direct access to the information on the stack. The
  PIC18 microcontroller diverges from this tradition
  slightly. With the new PIC18 core, users now have
  access to the stack and can modify the stack pointer
  and stack data directly.

I am confused. How come there are RTOSes made for PIC microcontrollers that work with PIC16 cores? For example, OSA RTOS is available for PIC12/16 with mikroC compiler.

Can you direct me to some resources, or if possible give examples, so that I can learn about stack switching?


texts: I am designing a circuit in OrCAD 16.5.  I have added the libraries in the "place part" section and have used the LM837 and LT1115 Op Amps.  When I create my netlist, I am getting the warning "No PSpiceTemplate for U5B, ignoring" and the parts do not appear in the netlist.  It appears that I do not have the libraries for these files, but I dont know how to add them (or where to get them from).  I assumed they were in OrCAD as I was able to place the part.  Can someone help me out with this problem?


texts:
Hi I am building a PCB using eagle and its the first time I am using an IC. Two questions arose.

Do I need to connect the IC chip's ground, because eagle did not do it?
Do I need to make sure all of the ground orphans are connected?

Thank you guys in advanced!


texts:
I want to design a full adder of one bit numbers using 2/4 Decoders and NOR gates.

I have the truth table:

Now, what's confusing me are the inputs and outputs. The inputs for one DEC would be A and B, right? What do I do with Cin and Cout? Everything goes into the NOR gate and there's S, but how to get there?


texts: Incorrect voltage readings from ADC and op-amp

texts:
I recently posted, but my schematic changed and so did my problem.

I have this set up and on my raspberry Pi I have this code running which gets the 10-bit number from the ADC and converts it into a usable voltage for me.

#!/usr/bin/python

import spidev
import time
import os

# Open SPI bus
spi = spidev.SpiDev()
spi.open(0,0)

# Function to read SPI data from MCP3002 chip
# Channel must be an integer 0-7
def ReadChannel(channel):
  adc = spi.xfer2([1,(8+channel)<<4,0])
  data = ((adc[1]&3) << 8) + adc[2]
  return data

# Function to convert data to voltage level,
# rounded to specified number of decimal places.
def ConvertVolts(data,places):
  volts = (data * 5) / float(1023)
  volts = round(volts,places)
  return volts

while True:

  # Read the MCP3002
  ADC_volts = ReadChannel(0)
  digital_Volts = ConvertVolts(ADC_volts,2)
  print digital_Volts

simulate this circuit – Schematic created using CircuitLab

The problem I am having is that if I run this I expect to get a constant 3.3V reading in my program. However, I do not. I get a fluctuating reading between 4.34-4.63V.
I need to establish a constant voltage because I intend to include a piezo element to detect voltage from vibrations and the signal needs to be biased to get both the pos+ and neg- voltages produced.

Can anyone explain why I don't get 3.3V, and why I don't get a constant 4.5 or near abouts reading but a fluctuating value?
Thank you


texts:
I have a couple questions about boost and buck converters.

First, do they try to hold the output voltage constant, or do they alter the input voltage by a constant factor? For example, if I change the input voltage, will the output voltage change?

Secondly, what happens when you give a higher voltage than you're trying to achieve to the input of a boost converter (or a lower voltage to a buck converter)? For instance, let's say I was trying to use a buck converter to convert some voltage to five volts. What would happen if I gave it 3.3 volts on the input?


texts: Does anyone know the typical receive power for a Bluetooth radio when receiving audio either A2DP or ATX?  I want to do some system power analysis to examine the radio power as part of the overall system for a TWS application.  Thanks in advance for any help.


texts: Best way of connecting ATMega32 to LCD with 16 pin

texts:
I am trying to control LCD ADM2004D with ATMega32 AVR microcontroller. This type of LCD is 20x4 character, has 16 input and I am going to connect the main board to this LCD. I may need to disconnect it from the board sometimes. What is the best way of connection, in term of wires and male/female sockets.

I am thinking about ribbon cable. But there are so many types of cable and I am not familiar with their name. I look for something neat although I know everywire does the job.


texts:
I am using Some arduinos (5V Pro-Mini, but planing to move to actual ATMEGA chip) over a distance of few metres.
These are connected using standard Alarm cable (I had problems with Ethernet cable and 12 volts leaking between cores)
In  mine set-up the cabling caries DC~12V (bit bigger closer to the source and backup car battery)I am protecting mine inputs using resistive divider (all the inputs where designed to be around 12VDC(then dropped to around 4.3VDC when HIGH) ground is connected through diode to protect polarity.
Problem is How to protect the RS-232 from being either shorted to or connected to 12DC (or ground) incorrectly.
I am planning the possibility when cabling may extend up-to 60-70 metres.

I have been considering the Zener diodes, but I am not sure how effective would 5.1V + margin be. while the 4.7 model might be too low and short the standard communication
Although I do not know what level the internal protection has from over-curent against ground.

Edit:
I am using UART on a chip (directly on a logic level)
the baud rate is intentionally slow and data send (including self-diagnostic for data corruption)is minimal generally less then 2 bytes per second.


texts: Settling time for an LR circuit with an AC sine source

texts: How can we mathematically relate the settling time for an LR circuit with an AC sine source? By settling time I mean the time taken for the circuit reaching to steady state from transient state. This is related to the previous question: Miscalculation of current for a pure inductive circuit in LTspice


texts:
I am designing a dc dc isolated forward converter that accepts 20V and outputs 10V(Imax of 5Amps). As part of the study I was reading this document
Document
In the page 15, it shows a transformer which has the symbol shown below -

What kind of transformer is this ?


texts: How to scale and shift a signal with a single opamp?

texts:
I tried to scale the signal by 3 times with Av=1+R2/R1. but how do I shift it up by 1v?
for example: a 0.2/2V VIN into 0.6/6V and shift it up by 1v to 1.6/7v?
I managed to scale it but I don't know how to shift the Vout signal.


texts: LED bar pattern shift (right to left) using 555 timer resistors and LEDs and SIPO shift register

texts:
I've build the 555 timer and got my resistors and LEDs ready.

What I don't know or understand is how to shift a pattern using the serial in parallel out shift register (SN74LS164N).

I want to shift 10001100 using the shift register to shift LEDs (8 outputs).  How can I do that? How can I make the connections or what are the connections? Or is there any other way without using this type of shift register?

Components that I've used:
555 timer
capacitor
resistors
LEDS
SIPO shift register SN74LS164N

is there anything else i need to add to the diagram? that will make the LEDs shift in the pattern


texts: Power tool safety: Grounding v/s Double insulation

texts:
OSHA regulation 29 CFR 1926.404(f)(7)(iv) states that electric power tools must be grounded except when they are double insulated. I quote from the Black & Decker rotary drill manual: "Do not use any adapter plugs with earthed (grounded) power tools".

Could someone please explain why power tools use adapter plugs without the ground pin and how is "double insulation" a substitute for grounding ? Thanks.


texts: Silent alternative to 3A relay to be controlled with Arduino

texts:
I wanted an alternative to relay which I can control with an Arduino since a relay is too loud.

I already have a cd4066 bilateral switch but it isn't working in my case because it leaks current.

So was looking for an alternative which is silent and should be able to handle 5V at 3A and be controlled with an Arduino.


texts: Choosing voltage divider resistor values

texts:
Above is the circuit in question.

R1 and R2 forms a voltage divider to supply desired current for the load.

On the left side there is the original circuit and on the right side its Thevenin equivalent.

Lets say the ideal supply voltage is known and we want 0.01A current through our load RL which is 100 ohm.

So we can write the given and desired as:

Vcc = 5V

Ith = 0.01A

RL = 100 ohm (load resistance)

Here we can employ the Kirchhoff's law for the Thevenized circuit as:

Vth = IthRth + IthRL

Vth - 1 = Ith*Rth

5*R2/(R1+R2) - 1 = 0.01 * R1*R2/(R1+R2)

R1 = 400*R2/(R2+100)

So now we have a relationship between R1 and R2.

For example:

if R2 = 100ohm then R1 = 200 ohm

if R2 = 10k ohm then R1 = 396 ohm

So far so good. If we plot R1 versus R2 for 1 to 100ohm and 1 to 10kohm we obtain the following plots:

It seems like for R2 at around 10k, R1 goes to a limit like 400ohm.

I think one can choose here like 400ohm for R1 and any resistor above 10k for R2.

I also noticed if R1 and R2 is low resistances such as R2 = 100ohm then R1 = 200 ohm, the current flowing through R1 and R2 is much higher.

Here is my question:

Does that mean we should avoid choosing low resistors for R1 R2 just not to drive more current?

And if so, what is the rule of thumb if we only know the exact value of RL and the relation R1 = 400*R2/(R2+100) ?

I mean is there a rule of thumb between RL and Rth or RL and R2? Would you have a rule of thumb between RL and Rth or RL and R2?


texts: How is the input not floating when there is a pull-down resistor?

texts: I am wondering why the input to D2 will not be floating when the switch is open. If the switch is open, wouldn't it act like a mini antenna and provide a random input to the D2 pin?


texts:
I have been looking for a level shifter capable of doing 1.8v to 3.3v. For whatever reason it seems almost everyone carries 2v to 3.3v shifter but 1.8v to 3.3v are few and far between. For practical reasons it should be at least 4 bit, preferably 8 bit. There are single-bit converters like that but it gets a bit daft doing 5 bits that way..

Can anyone recommend a logic family to use?
Some examples I've gone through so far:
74LVC8T245 (texas)
74AVC8T245 (nexperia)
74LVT244 (nexperia)
74LVT244 (texas)
74AVCH4T245 (Nexperia)
74AVCH4T245 (Texas)

I've actually found one chip that's good - Onsemi 74VHCT125, works from 2V to 5.5V and valid input high level starts at 1.2V. Now if only I could find a second source.. NXP, Toshiba and STM VHCT logic don't like 3.3V VCC. Texas has SN74LV4T125 which is valid but costs 3x more, Nexperia LVT125 doesn't do 1.8v.

Am I overlooking a logic family here, both of these look like corner cases that don't really fit either logic family, with other manufacturers having same families with different specs..

update
After sleeping on it I realized the chips featuring 4 or 8 (e.g. AVC4T245) actually have separate power for either side. I was just looking at the datasheet "3.3V min 2V logic high" line without realizing the VCC on the input side is 1.8V.

An omitted detail from my description was that there's a reasonably fast serial bus with flow control (2+2 lines) and a bunch of mostly static control signals. For the latter a simple PNP level shifter is perfectly fine.


texts: Differential to single ended audio signal

texts:
I'm working on an interface that will be connected instead of a speaker, input of my interface is differential, and output is single ended.

I'm using the following schematics :

R3 is the load to simulate the speaker, the R1/R7/R4 group is here to decrease the level.

I would like to easily adjust the gain by acting on R2  (knowing that I should act the same on R5) but I need a major value change to see a minor change on the output, I'm using Proteus to do the simulation.

Do you see an alternative to my scheme? or can I use a transformer to move from differential to single ended then use an AOP to adjust the gain?


texts: Help for voltage is being passed trough load, even triac is OFF condition

texts: We are using below circuit for home automation. We are facing problem when 5v battery is not passing to the circuit,but even 1 volt is being passed trough load, even triac is OFF condition.. Please help us to fix this issue.


texts:
Question 1:

I have been looking around and could not quite get my head around if the same principle of high voltage and low current conversion applies to capacitors as with "power lines".

For example, say you need 10V at 100A, you can get it from say 10,000V 0.01A by stepping it down to the required voltage and current.

Now, from what I understand of capacitors, with them you can store high voltage and high current (correct me if I'm wrong).

Will you be able to get, say, 10V at 1A from a 400V 22,000μF capacitor? Should it be stepped down?

Question 2:

400V across 10,000μF = 800J

800J for 1s = 800W

400V at 800W = 2A at 400V for 1s if this is right?

So if I pull 100V at 2A I could use it for 4 seconds?

Please guys, no confusing formulas as I use online calculators. I'm still getting to know this stuff first.


texts: porting the Auto placing component of eagle software to Easyeda software

texts:
I found Easyeda and surprised by its community with many opensource projects on its site.

but i am some partly lazy and like to have the auto place component on the PCB part, which is not exist at easyeda so i found eagle which is free for some small project, which have had the auto placement by external scripts. So my problem is to exporting the schematic from easyeda to eagle.

So i like to know how can convert the auto place script for eagle to using in easyeda, the instruction for this action (auto palceing ... ) can be see here:

by using autoplace_v3.ulp file like this:

/* Simple autoplace ulp based upon component position in schematic

* this ULp was origianlly written by one of the CADSOFT team I believe

* apologies for lack of full reference and acknoledgement

* run the ULP in the sch window and run place.scr in BRD

* changing the scale parameter will produce tighter/looser grouping

* Ideally stick in a pop-up window to select scale and x/y offset at some time

*/

string c,cmd;

real scale = 0.75;

int HasPins,

    IsSupplySymbol,

    Px, Py, xoffset, yoffset,

    ix,

    GridDist = 50,

    ShOffset = 3000,

    y_ShOffset = 4000,

    x_ShOffset = 7500;

                   output("place.scr") {

                    if (schematic) schematic(SCH) {

            cmd+= "board; \n";

                       sprintf(c, "Grid mil 50;\n");

            cmd+= c;

                       SCH.sheets(S) {

                         S.parts(P) {

                           ix = 0;

                           P.instances(I) {

                             if (ix==0) {

                                Px = round(scale*(u2mil(I.x)) / GridDist) * GridDist;

                                Py = round(scale*(u2mil(I.y)) / GridDist) * GridDist;

                                }

                             HasPins = 0;

                             IsSupplySymbol = 0;

                             I.gate.symbol.pins(PIN) {

                               if ((PIN.direction == PIN_DIRECTION_SUP))

                                  IsSupplySymbol = 1;

                               HasPins = 1;

                               }

                             ix++;

                             }

                           if (HasPins && !IsSupplySymbol) {

                xoffset = x_ShOffset*trunc(0.5*(S.number-1));

                yoffset = y_ShOffset*2*frac(0.5*(S.number-1));

                              sprintf(c, "Move %s (%d %d);\n", P.name, Px+xoffset, Py+yoffset);

                cmd+= c;

                              }

                           } easyeda// end parts

                         }   // end sheets

                printf("GRID LAST;\n");

                printf("RATSNEST;\n");

                      }

                    }

exit(cmd);

ant the place.str file which automatically made by the autoplace_v3.ulp file inside the project file is like this:

GRID LAST;

RATSNEST;

like this:

Also i like to know what software do you know which have both capability like big open source community and the auto placement component in PCB designing part at once?

Thanks.


texts:
I'm working on a battery powered device that has 4 individual LED drivers. The output from the LEDs are controlled with separate PWM signals from a small MCU.

This has to be low cost, and a low cost way to regulate the current through the LEDs is to use current sinks but I have trouble coming up with a good circuit.

Circuit 1 is simple, cheap and robust, and it is independent on the level of the PWM signal as long as it is high enough to turn on the MOSFET. The disadvantage is that the voltage drop over R(set) has to be 0.5-0.7 volts before Q2 starts conducting. The LED with the highest Vf has a forward voltage of 3.6V (max). A constant 0.5-0.7 volt loss is fairly high when using 4 AA cells.

Circuit 2 is potentially more efficient as there is no diode drop. I can use a small R(set), say a voltage drop of 0.1 volts. Since both op amp terminals has to be at the same potential, I'll have to drive the op amp with a 0.1 volt PWM signal and that seems awfully small. A big disadvantage as I see it is that the current is directly related to the input voltage on the non-inverting pin. I'm worried about noise on the PWM signal.

Any ideas for a high efficiency low cost current sink? Either an improvement on the above, or a different approach?

EDIT: To clarify, "efficiency" may not be the right description, the goal is to get more power out of the batteries. A 0.6 volt difference means more power over the life of the batteries.


texts: Most efficient use of resistors to heat an aluminum plate?

texts:
I'm building a reprap printer.  I have a sheet of aluminum about 8x8" to use as the print surface, which must be heated to prevent problems while printing.  </background-info>

My controller board can handle a maximum of 60V @ 11A, before either the PTC fuse trips or MOSFET overvolts.  I'm not changing these components, so whatever solution I find has to fit within these constraints.  I have 12x  1 ohm, 10W aluminum chassis-mount resistors that I intend to abuse as heater elements.  I'm trying to find the most efficient way to parallel/series the resistors and what supply voltage to use to draw the most power.  Existing power supplies I have are either 12V @ 18A, or 24V @ 6.5A, and I would prefer to not purchase another one if possible.

Exceeding the wattage of the resistors temporarily is perfectly acceptable, because I'm only shooting for a target temperature of 65-110C (depending on the plastic used).  Any solution I'll be happy with should hit that temperature within 10 minutes or so, so pushing 25W through a 10W resistor in that time won't really cause them damage.  And if it does, meh, they're a buck each.  After the platform is at temp, a microcontroller will cycle the power of the resistors to control the heat.


texts: Can anyone help me identify this component? SMD P636

texts:
I damaged a BMS board by briefly shorting some connector leads. The only chips I see that appear physically damaged at the two marked by the red box in the image below. I can't seem to find those components in my usual places. Anyone have ideas that could point me in the right direction?
Thanks for your help. Any suggestions would be welcome.


texts: Getting the Thévenin equivalent resistance for a max power problem

texts:
The given question :

I went on to get Rth by adding a voltage of 1v to control the dependent source from which I obtain the current in the branches and get the total current , as follow then later decide it by 1 since 1/I =v by ohms law to get Rth:

But in the the answer of the text book I’m using ((fundamentals of electric circuits 5th ed chapter 4 practical problem 13)) , no 1v voltage (or current ) were introduced and he solved as :

Which I found very confusing.

So the bottom line is :
When and when not are voltage sources introduced in the analysis to get Rth when there’s a dependent source ?


texts: How to find the optimal speed of a BLDC motor having hall sensors? Can we change the most efficient speed through the controller?

texts: How do we find the speed of BLDC motor at which it has minimum electrical losses so that we design a gearing system accordingly. And can we change the most efficient speed of a BLDC motor to suit our requirements.?


texts: Inexpensive multimeter for integrated current measurement

texts:
I'm building a simple circuit with an Arduino Nano board, which will read signals from a Hall sensor and periodically send pulses to a small 5V solenoid. I'll drive it from 6xAA batteries in series, producing 7.2V. The on-time of the solenoid will be very short, and with a small duty cycle that will vary quite a bit (say 1% to 10%). I find here that the solenoid consumes 240mA at 5V if always on, and I guess the board and other bits-n-pieces would add another 50mA?

So, I'd like to be able to measure the current consumption over a set time period, such as a minute or five minutes - with an end goal of reducing the ongoing consumption (I'd like to use 6xAAA batteries, but AAs may be necessary, depending on how low I can push the current draw). However, with the current varying wildly over time, it is hard to get a static readout from my digital ammeter (it takes a good few seconds to settle) and they generally will change frequently (<0.1 sec).

A bit of research shows that I need an integrated ammeter, i.e. an ammeter that integrates over time as here. This question here is interesting, but answers recommend building such a device with an Arduino! I wonder, can such a thing be purchased inexpensively, ready-made?


texts: DS2431+ EEPROM Toner cartridge Information

texts:
I have an Toner Cartridge with EEPROM of model DS2431.

I am able to read the bit data from the eeprom using Arduino OneWire library.

I am also able to write to the eeprom.

But when I write to it I am not able to write it again. And also when I erase it, it has same issue that I cannot write to it again.

I want to know that. Is DS2431 Eeprom only write once?

If no how can I rewrite to it again, even after erasing it.


texts: Correctly wiring batteries for solar charging

texts: Can I charge a standard crank 12v car battery in parallel with two 6v 225ah batteries that have been wired in series using a solar charger.


texts: Why are there so many USB connector types?

texts: Why are there so many different USB connector types?  Is it just that they've gotten smaller as Moore's Law progressed and there was a need for smaller connectors, or is there something more?


texts: Altium - convert blind via to through hole

texts:
I want to convert blind vias to through hole (4 layer board) like shown below:

How do I do this?


texts: Building a numeric potentiometer for AC current

texts:
I'm building a bench to calibrate a device that measures AC currents. As I won't build something accurate, the current will be measured with a current clamp and a multimeter (voltage mode).

For the current load, I first tried a diode bridge with big capacitors and after it, a DC current load (voltage / current converter).

The result is a non sinusoïdal voltage at the clamp output due to the diode voltage which leads to 0 current when the input voltage is less than twice the diode voltage. Like in this screenshot (orange = input voltage, yellow = clamp output (volt)).

The problem is that the multimeter does not integrate correctly the non sinusoïdal voltage of the clamp and outputs a wrong rms value. If I plug the multimeter in-line as an ampere meter, the measure is correct but I need the clamp because I will measure currents that are beyond what the multimeter can do

That's why I want to build a device that operates likes a rheostat. Its resistance should be defined by a microcontroler and the current vaweform should be proportionnal to the voltage waveform.
Maximum dissipated power is around 60W (for the purpose of my specific design, I can add a serie resistor to drop the power in the device down to 20W)
Input voltage: 6V 50Hz AC sinusoïdal.

How can I do?


texts: Max power transfer of source with variable internal resistance

texts:
I have been reading how to obtain maximum external power from a source using the maximum power transfer theorem. However, it is for a source with a finite internal resistance.

Can you have power sources with a variable internal resistance?
How would you find (or calculate) the maximum external power of a source with a variable internal resistance (Theoretically, if you can't have a power source with a variable internal resistance)


texts: pulsed current with 200 kHz squarewave signal

texts: I use this circuit  to obtain pulses as close as possible to the input signal pulses on the 1.5 Ohms resistor. The MOSFET is FPQ50N06 and the transistor is BC239. The circuit gives good results on 25 kHz, 4.8 Vpp and 1.5 V offset. However, I need 200 kHz, 4.8 Vpp and 1.5 V offset. How can I make it work when the signal is 200kHz? (I connect oscilloscope probes shown on the scheme and I exactly need on channel2 (CH2) the pulses shown on the other image which is an oscilloscope screen.)


texts:
Consider I have a 2.048-volt reference voltage, for example, I build this voltage with REF191, this IC has only 10mA output current, How can I boost this current to 200mA?
is there any better way to build accurate 2V with 200mA output?


texts: HF arc starter and full bridge IGBT driver protection

texts:
Had developed HF arc starter scheme  and it worked fine until I accidentally pressed arc start push button when circuit was shorted (torch stick on work peace). After that all 4 IGBTs in my inverter blow up. Inverter uses full bridge output scheme built on FGH60N60 IGBTs.

Both L1 and T2 are massive (150mm in diameter) ferrite thoroids.
HF arc module is like this

I think damage was due L1 saturation (short circuit), so it loosed reactive resistance vastly and high voltage leak to inverter, is this correct?, any suggestions?

Components was chosen based on availability..
Sorry for bad English


texts: Use 5w/3w 12vdc LED on 60w 12vac cdi ignition

texts:
I'm building a vintage two stroke race bike out of a 78' puch maxi. The original points setup is junk and I'm switching to a CDI.

I have an LED headlight that I'd love to use for aesthetic purposes.

The CDI has a output of 60w 12vac the LED headlight needs 5w/3w 12vdc. I have the understanding that a rectifier will solve the AC/DC problem, but should I be concerned with the wattage output of the CDI blowing my lights?

How do I solve this problem? I have a basic understanding of electricity, but when regulators/rectifiers, resistors, etc. come into conversation I am lost.

Below are the links to the two products I plan on using. Any and all input will be appreciated. Thanks.

http://www.treatland.tv/PUCH-HPI-CDI-mini-rotor-ignition-system-p/puch-mini-rotor-210k012.htm

http://www.madhornets.com/motorcycle-headlight-5-led-head-lamp-harley-bobber-chopper-touring-blk-yel/?gclid=Cj0KEQiAxrW2BRCFidKbqKyq1YEBEiQAnMDWxig6iev2zXfebXgD2sIAjzsJdKjaw7g4NOXPKeaUq5UaApP38P8HAQ


texts:
What should be the Minimum or maximum input power cable length can be used in Conducted emission test.

Length from EUT(DUT) to LISN.

What if my product come with input cable length out of MAX limit.


texts: How do I calculate the current needed to prevent corrosion on a piece of metal?

texts:
Consider I have a piece of aluminum and a caustic bath of some Ph level. If I stick the aluminum in the bath, it will corrode over time depending on the Ph level of the solution.

I understand it is possible to prevent corrosion by applying current through the metal. If the bath is the electrolyte what is anode? Can the aluminum be both, or must it require a sacrificial piece of metal?

Also, is it possible to take some electrical measurements of the solution to determine how much current is required to flow through the cathode to prevent corrosion?


texts: What cause sudden spike in the output voltage of transformer?

texts: What issues can cause the output voltage of a transformer to suddenly increase from 230 volts to 400 volts (in the case of any transformer and in the case of the delta to Y configuration of the transformer)? What would be the voltage between a phase and ground if a coil of the Y side (secondary) gets short because of heating or any other reason?


texts: RGB LED Resistor Value and Source Voltage

texts:
I am using a Common Anode RGB LED in my project(datasheet is given below) and the different specifications for each LEDs are giving me headache. In my schematics, as shown below, I have used individual current limiting resistors valued at 150ohm. The common anode is tied to the 3.3V source. The LEDs are driven by an NPN and the switching is controlled by an MCU.

The RED and BLUE LED have max VF=2.4V and 3.15V, which is smaller than the source 3.3V

I have a feeling that something is off in my schematic design.


texts: Any physical barrier to read an HDMI input?

texts:
I'm considering coding a software that would read data sent from a device (game console, computer, ...) via HDMI. The program would then be able to display the shared content inside a window, which would make it possible to use a laptop screen as a monitor. More info on what I'm trying to do here.
I'm aware that an HDMI-out port of a laptop can't be used to retrieve data. I would rather use an USB port, with potentially a HDMI to USB adapter.
My question is : Is there any physical barrier blocking me from retrieving an HDMI output from USB port, manipulating it in my program to somehow display it on screen ?
In my mind, this should just be some transfer of bits. With the right protocol understanding, my program should be able to retrieve the data one way or another. But I must admit my knowledge of HDMI and hardware is really limited. Any redirection to web content, doc, tutorial or blog would be greatly appreciated by the way.
Thank you.


texts: Can electronic components work without power?

texts:
Can electronic components work without power,with the help of temperature?
according to my knowledge,I don't think so,until heat will generate some energy and that will drive component. I have to make a circuit now,which has no power but has temperature of around 130 C
how can I get the power for the circuit from the temperature?


texts: what is meant by Divide by N and Modulo(N) in counters?

texts: I am trying to understand counters. Can anyone of you clarify me about terms (Divide by N) and Modulo(N) used in counter? What exactly it means?


texts: Where and how do I put an inductor on a volume control

texts:
I built an stereo equalizer but I made some mistakes. As the potentiometers didn't fit on my PCB I had to put them separated and make the connections with some wires. The other mistake is that I made a virtual ground instead of a real one.

This mistake causes the equalizer to amplify all the noise from all the mobile-phones sitting around in my house and makes a very annoying noise. It works fine when no phone is around (but this isn't the normal condition).

I bought some ferrite toroids to wind the wires around them. But I don't have enough for all the wires I have in here (they wouldn't fit in the case anyway). So some wires will have to share toroid.

Here is an example for how I think it could bee:

simulate this circuit – Schematic created using CircuitLab

So my big question in which direction should I turn the wires around the toroid?

I know I can turn one wire in any direction I like to if it's only one. If I put two wires around a ferrite toroid I have to care about the relation between these two wires (also easy). But when it comes with this case I don't know how to deal it.

Should I turn all in the same direction? or 2 in one direction and 1 in the other direction? or should I avoid one of them?

If someone could please explain what should I care about? I don't want just a make this or make that solution since this is something I can do on my own.


texts: How to best clean this sealed mechanical rotary encoder / volume knob?

texts:
How can I best clean, replace or lubricate this fairly well sealed digital rotary mechanical encoder?

The equipment operates, but the encoder is super finicky, often encoding in the wrong direction when spun.  With patience it's possible to get it to the right value, but quite tedious.

The equipment is about 15 years old, and the encoder has been unreliable for the last year or so.

Question 1: if it can be replaced, how would I find a pin for pin match?

Question 2: if it can't be replaced, what's the best way to clean or re-lubricate it?  It has a crack, I can probably flood some chemical junk into it.

Update: I opened the cleats:


texts: What is the typical on-resistance of an MCU output?

texts:
In my case I am using PIC24F and dsPIC33F microcontrollers, but where is the on-state resistance of an IO port for a PIC stated in the datasheet? I cannot find it anywhere. And how does this apply for other processors - 16F/12F PICs, PIC32, MSP430's, AVR's etc.

The reason I ask this is because I am designing a sensitive circuit which changes the range of an ADC input by leaving a 10k resistor floating or grounded. If the on resistance is in the 100's of ohms, this will introduce a 1% or more error term.


texts: Merit and meaning of fractional bandwidth

texts:
What is the merit of fractional bandwidth?

$$f_{fractional}=\frac{f_{higher}-f_{lower}}{f_{mid}}$$

The same absolute bandwidth will have a smaller fractional bandwidth, if the mid frequency is higher, ok. It is reciprocal to the Q-factor, ok. Still, I could not find a good explanation why I would use the fractional bandwidth to describe for example a filter instead of absolute.

The only source I found is this page, look for paragraph How to judge fractional and relative bandwidth?


texts: Implementing a simple 1/s integration in PSCAD while it only offers 1/sT

texts:
So I'm doing some modelling in a power systems simulation software (PSCAD)

I'm using the integrator block in that software.

Now unlike SIMULINK PSCAD doesn't offer a \$ 1 \over s \$ block but offers a \$1 \over s*T\$ block where \$ T \$ is the time constant.

I just want a simple integration operation done, i.e:

When I input

$$
A*sin(100t)
$$

I want to get

$$
-(A/100)*cos(100t)
$$
What should I set the time constant \$ T \$ to get this basic result?


texts: Q: Can I use the LM3914 voltage indicator IC as a low-voltage cutoff device?

texts:
I came across these two circuits, and tried them out successfully:

LM3914 Battery Monitor, drives 10 LEDs in a linear relation to the input voltage.

NE555 Low-Voltage Cutoff, uses a 555 timer to switch off a circuit at low voltage, with hysteresis to prevent uncontrolled switching.

My question is, is it possible to combine the two? That is, use the LED outputs of the LM3914 to control the low-voltage cutoff behavior of the 555 timer?

EDIT Circuit details:

I have a 12V lead acid battery, I want the circuit to automatically cut off power at 11.5V and restore power above 12.5V. With a bit more research, I think I can directly hook up the appropriate LED pins of the LM3914 to the trigger and reset pins of the 555? Can anyone confirm whether that's right?


texts: Double Side-band Amplitude for Radio Transmission & Single Side-band Reduce Carrier for Point-to-point Transmission

texts:
What are the reasons which lead to the use of double side-band amplitude for radio
transmission, and single side-band reduce carrier working for point to point transmission?

Thank you for your help.


texts: Does a circuit of 3 LEDs connected in series to a 9v battery work?

texts:
Excuse my noobishness....

I'm buying these 10mm white LEDs on Amazon, and I want to connect 3 of them in series to a 9v battery. Is the 9v battery enough to power all 3 of these LEDs?

Is this a circuit that I could add a resistor to? If so, how many ohms should the resistor be? Thanks!!


texts:
I'm designing a 4 layers PCB in Altium Designer 19.1. My PCB have a ground plane on layer 2 and a small copper pour area on layer 1. The copper pour area on layer 1 is connected to the ground plane using vias. Currently those vias have thermal relief on layer 1 and 2 but I would like to change the polygon connect style of those vias to direct connect. I have other vias, outside the small copper pour area of layer 1, that connect to the ground plane on layer 2. I would like the polygon connect style of those vias to remain unchanged. How could I do that? Would creating a new polygon connect style rule with the query TouchesRoom('Name Polygon Layer 1') work? I suppose it won't since polygons and rooms are two different things.

Thanks!


texts: adder in binary addition: XOR instead of OR gate

texts:
I am just a newbie starting out in electronics with no experience.

Why do we need XOR and AND gate for the binary adder? is there any particular reason why only these two specific gates are needed and used?

As I understand OR gate adds values (boolean algebra - X = A+B then why we use XOR gate at the beginning of the circuit and not OR gate?


texts: How do I approach this ideal op-amp problem?

texts:
This op-amp problem has been giving me issues. I see two inverting op-amp circuits which I'm sure I should be able to use to simplify this problem, but that 10k resistor at the top is making the analysis difficult. Since that resistor is there, doesn't it change the output of the first op-amp?

How do I approach this?


texts: USB EHCI, compatibility with low speed and full speed devices

texts:
Can EHCI be used with USB 2.0 low speed and full speed devices?

Basically the datasheet of ATXMega256 says that its USB 2.0 port supports full and low speed modes. I want to know if I can connect with a USB port being controlled by EHCI.


texts:
I know how to simplify digital circuits using Karnaugh maps. However, the resulting circuits always consist of only not, and and or gates (basic Boolean algebra operators).

Often, by using other gates (xor, nor, xnor, nand, etc) you can get a simpler circuit.

What techniques can be used for this simplification?


texts:
I know how a standard LCD screen in a calculator is multiplexed (Shared rows and columns), but I've recently seen a highspeed recording of a modern LCD Display (PC Monitor) and it didn't flicker at all. How are those types of displays multiplexed nowadays?

Link to the video:
https://www.youtube.com/watch?v=0lvtqqlhem8

The flicker at the LED screen is only the PWM of the LED backlight, so the LCD itself shouldn't be flickering...


texts: Which is more efficient: A much larger than needed step-down voltage converter, or one rated closer to the actual load?

texts:
I'm designing a custom audio system for my electric motorized pedicab. The motor of my cab runs on a 48 V 33 Ah battery, and I have planned to use a 48 V to 12 V step-down converter to simultaneously also run my lights and audio system. I am new at all of this and have been learning a lot, but am nervous I am going to either:

overload something (like my battery) or,
lose a lot through the inefficiency of my system.

My batteries are rated for a continuous draw of 50 A. I have been told to set aside 30 A for my motor, so that leaves me with 20 A for lights and audio.

The cab comes with a 20 A rated 48 V to 12 V step-down converter installed. I was worried about peak draw from my amplifier/speaker system and purchased a 60 A converter to use instead. Someone on an audio forum pointed out that, while yes this would protect me from any peaks, it would be much less efficient as these step-down converters are more efficient as you get closer to matching the actual current that runs through them with their capacity.

Is that true? Will my 60 A rated 48 V to 12 V converter be less efficient than sticking with the installed 20 A one? My amplifier puts out 45 watts RMS per channel and I was hoping to bridge my speakers, so that's 90 watts RMS per channel for a total of 180 watts. 180 watts at 12 V is 15 amps. Folks on the audio site also said I'll never ever get close to this and will most likely only ever draw 2-3 amps at a time. That makes sense because the amplifier has a 15 A fuse on it, so I'd like to think it would never get close.

Since I'm running a mobile system, it's important to me for it to be efficient. I misread the advice I was given and bought this 60 A step-down converter, but have now realized that perhaps it will be more inefficient than the installed one. I'm fine sticking with the 20 A installed one IF it's not going to hit its upper limits. I'll probably be using just over 5 A for lights as well, so really I only have 15 A to work with for audio.

As I stated, perhaps I'm overly worried and my audio system will hardly ever draw anything at all. I'm using a class D amplifier and two 6x9 3 way speakers, rated at 150 watts RMS with a sensitivity of 93dB.

Thanks for any and all help! I've got to figure this out in the next week.


texts: Why doesn't my STM32F4 PLL seem to work?

texts:
I've spent a few days unsuccessfully trying to get my Nucleo F401RE to use the PLL for its system clock. I've configured it to use the 8MHz HSE and output 84MHz as the system clock. The code stops executing when it gets to:

// Wait for clock source to change
    while ((RCC_CFGR & (2 << RCC_CFGR_SWS_BIT)) == 0);

I'm outputting the PLL clock on MCO1 and the HSE on MCO2, and I see a flat (high) PLL and an 8MHz HSE. I presume SWS never indicates the PLL is the system clock because the PLL is not correctly configured, but it does make it past waiting for PLLRDY.

I'm using the following code (specifically not using CMSIS, because I want to figure this out manually):

#include "stm32f4.h"

#include <stdbool.h>

void led(bool on) {
    GPIOA_ODR = on ? 1 << 5 : 0;
}

void init(void) {
    // Enable GPIOA peripheral clock
    RCC_AHB1ENR = RCC_AHB1ENR_GPIOAEN | RCC_AHB1ENR_GPIOCEN;

    // Set PA5 to output and PA8 to MCO1
    GPIOA_MODER = 0b01 << 10 | 0b10 << 16;

    // Set PC9 MCO2
    GPIOC_MODER = 0b10 << 18;

    // Turn on HSE
    RCC_CR |= RCC_CR_HSEON;
    while ((RCC_CR & RCC_CR_HSERDY) == 0);

    // Set flash wait cycles
    FLASH_ACR = FLASH_ACR_PRFTEN | (2 << FLASH_ACR_LATENCY_BIT);

    // Configure PLL
    // System clock = 84MHz, PLL48CLK = 48MHz
    RCC_PLLCFGR = (RCC_PLLCFGR & RCC_PLLCFGR_RESERVED_MASK)
        | RCC_PLLCFGR_PLLSRC // Set HSE as PLL source
        | (4 << RCC_PLLCFGR_PLLM_BIT) // M = 4
        | (168 << RCC_PLLCFGR_PLLN_BIT) // N = 168
        | (1 << RCC_PLLCFGR_PLLP_BIT) // P = 4
        | (7 << RCC_PLLCFGR_PLLQ_BIT) // Q = 7
    ;

    // Turn on PLL
    RCC_CR |= RCC_CR_PLLON;
    while ((RCC_CR & RCC_CR_PLLRDY) == 0);

    RCC_CFGR =
        (1 << RCC_CFGR_SW_BIT) // Use PLL as clock source
        | (0b11 << 21) // Output PLL on MCO1
        | (0b10 << 30) // Output HSE on MCO2
    ;

    // LED lights if set here

    // Wait for clock source to change
    while ((RCC_CFGR & (2 << RCC_CFGR_SWS_BIT)) == 0);

    // LED doesn't light here
    led(true);

    for (;;);
}

with these headers:

#ifndef STM32F4_H
#define STM32F4_H

#include <stdint.h>

#define REGISTER(addr) (*(volatile uint32_t *)(addr))

#define GPIOA_BASE 0x40020000
#define GPIOA_MODER REGISTER(GPIOA_BASE + 0x00)
#define GPIOA_OTYPER REGISTER(GPIOA_BASE + 0x04)
#define GPIOA_PUPDR REGISTER(GPIOA_BASE + 0x0c)
#define GPIOA_ODR REGISTER(GPIOA_BASE + 0x14)

#define GPIOC_BASE 0x40020800
#define GPIOC_MODER REGISTER(GPIOC_BASE + 0x00)

#define RCC_BASE 0x40023800

#define RCC_CR REGISTER(RCC_BASE + 0x00)
#define RCC_CR_HSEON (1 << 16)
#define RCC_CR_HSERDY (1 << 17)
#define RCC_CR_PLLON (1 << 24)
#define RCC_CR_PLLRDY (1 << 25)

#define RCC_PLLCFGR REGISTER(RCC_BASE + 0x04)
#define RCC_PLLCFGR_RESERVED_MASK 0b11110000101111001000000000000000
#define RCC_PLLCFGR_PLLM_BIT 0
#define RCC_PLLCFGR_PLLN_BIT 6
#define RCC_PLLCFGR_PLLP_BIT 16
#define RCC_PLLCFGR_PLLSRC (1 << 22)
#define RCC_PLLCFGR_PLLQ_BIT 24

#define RCC_CFGR REGISTER(RCC_BASE + 0x08)
#define RCC_CFGR_SW_BIT 0
#define RCC_CFGR_SWS_BIT 2

#define RCC_AHB1ENR REGISTER(RCC_BASE + 0x30)
#define RCC_AHB1ENR_GPIOAEN (1 << 0)
#define RCC_AHB1ENR_GPIOCEN (1 << 2)

#define FLASH_BASE 0x40023C00
#define FLASH_ACR REGISTER(FLASH_BASE + 0x00)
#define FLASH_ACR_LATENCY_BIT 0
#define FLASH_ACR_PRFTEN (1 << 8)

#define NVIC_ISER0 0xE000E100

#define SYST_CSR REGISTER(0xE000E010)
#define SYST_CSR_COUNTFLAG (1 << 16)

#define SYST_RVR REGISTER(0xE000E014)
#define SYST_CVR REGISTER(0xE000E018)

#endif


texts: Magnetic flux induced in toroidal core and conductor position

texts:
I was just reading Electric Power Engineering by Elgerd when I came across these statements about flux I couldn't fully understand:

  "By experiment, we can confirm a most interesting characteristic of the flux. If we keep the iron core position fixed but move the cable to any position inside the core window, the flux will not change. (The reader should contemplate what happens
  to the flux in the air core under the same conditions.)"

Why is this so? Shouldn't changing position increase flux in the regions of the core close to it and decrease in the far away areas? Is this the case for air core?

  "The flux will not change even if we bend the cable into any conceivable shape
  as long as the total current Ni remains unchanged and as long as it passes through
  the core window. In fact, the magnetic flux will remain unchanged if we replace
  the N-strand cable with an N-turn coil carrying a current i as long as the product
  Ni stays constant."

I have trouble imagining what the N-turn coil he's referring to would be placed like. Wouldn't it cause NI going in and coming out both?

Also, what would happen if I change the shape of the iron core itself keeping the cable straight? How would flux change then?


texts:
Is there a difference between having one big battery vs 2 batteries in parallel?
I am building a "fan controller" and want to power a 12V fan with a lithium ion / polymer battery.
The circuit itself is working as expected but the voltage drop on even a 10.000mAh battery is so high that the battery triggers the undervoltage protection on startup when the battery is at about 3.5V.
I tried to smooth the startup current with capacitors but can't really get it down. (At least not in a size that still fits the enclosure.)
Is there a difference if I use for example two 3.000mAh batteries in parallel instead of one 6.000mAh?
EDIT:
Thanks for the comments.
So first of all I am just a hobbyist and I am building this (at the moment) just with parts I had laying around.
The fan is a Corsair 140mm fan that was included with the watercooler (H110i V2 I think.) I do not have a datasheet, however I will see if I can find one.
The DC-DC converter is a MT3608. I am controlling the PWM signal with an NPN transistor and the power with an NPN Mosfet (on negative) and an ATtiny85.
I do not know the C rating of the battery, it was just a generic seller in my country and that a while ago (5 months I think), but at least on 10.000mAh shouldn't even 1C be 10A? I can't imagine a fan to need more than that.
I'll try to get all the details and update the post then.
EDIT2:
The Corsair fan is 12VDC 0.55A, probalby SP140L, the model number is 31-002574.
I could't find a datasheet.
Here is my schematic:

EDIT3:
Okay my schematics are actually wrong, I edited it to the right one.
I am also using an NPN transistor and mosfet, that was also wrong in my post, sorry!
I tried making a soft start with an NTC but the problem is the NTC holds its resistance for longer, so if I were to turn off the fan and turn it on again in a short time it would still have this behavior.
is there any other way to do this really simple but have it soft start every time?
I did it in software by not turning on the mosfet 100% and slowly increasing it to 100%, its working but the fan is making strange noises then.


texts: Testing AC generator on a Unity power factor (Resistive Load)

texts:
When I test a generator let's say 400kVA 0.8 pf 380V 3-phase on a unity power factor should I get a 400kW and 400kVA on the controller's screen? Because as we know in 1 pf KW= KVA but in 100% load I get  320kW 100% load and 320kVA 80% load. I can never get 100% KVA with 1 pf or the generator will fall down.

Why is that?


texts: Convert from a specific voltage range to another

texts: I need to convert the external control voltages of +4/-4V range to 0/5V in order to replace now obsolete SSM2050 with micro controller based solution inside an old vintage synth. Is there any easy and lightweight solution (like voltage divider) to  accomplish this task?


texts: What kind of application forces SMBus to specify a "TIMEOUT" that keeps the minimum frequency to 10Khz?

texts:
Why "TIMEOUT" has been defined in SMBus that forces the minimum frequency to be 10kHz?
Please tell a solid industrial application.


texts: Voltage present, even without fuse in DC distribution panel

texts:
I have an AC and DC distribution panel installed in my cargo trailer. And I think I have an issue with my DC side of the panel.
This is my first electrical work of any sort and thought it was going well until I checked voltage at the end of one of my circuits. I had 12v.  But no fuses in the distribution panel. I was expecting nothing.  I did wire up a small LED light and there was a faint amount of light coming from it.  If I put in the fuse, LED lights up with the expected brightness.
Are my expectations about having no voltage incorrect?
If they aren't incorrect, what are some troubleshooting steps I should start with?
The specific panel I am using is a Arterra WF-8930/50NPB Black RV Generator and Component (Distribution Center 30 Or 50 Amp Ac Service - 15 Dc Circuits -) and the manual is here.


texts: Can someone confirm how to wire this air pump?

texts:
I am trying my first 'electronics' project, involving setting up a pond aerator pump.  I purchased a Gast air pump, 86R123-101-N170X.  However, it came just as it was assembled at the factory and does not contain a conventional 3-prong plug.  I would like to add a plug to the exposed wires.

This document shows how it should be wired.  I have the 115V unit.

I understand that the brown and yellow wires go to the capacitor.

Is the white wire considered my positive (+) wire where current flows
in?
Is the joined blue and black wires considered my negative (-)
wire where current flows out?  The blue and black wires already come
twisted together at their tips.
Do I simply ignore the orange and red wires?  They too are already twisted together at this tips.  Do I just put a cap on the twisted end?


texts:
I'm toying around with a car window, and used this tutorial to try and make it work:
https://itp.nyu.edu/physcomp/labs/motors-and-transistors/dc-motor-control-using-an-h-bridge/

I've set it up almost exactly as the tutorial says, however i supplied 12v as i've found that's what the control motor needs. Furthermore i removed the switch, as i want to control the motor movement directly from the code.

However, when i turn on the arduino and the power supply, the window only moves a little; quickly slows down and then stops (i can still hear the motor trying to work though). I measured the output to the motor while running, and it seems it's only getting around 1,5V from the h-bridge in the start, and it drops while running.

The arduino code i'm using is very simple:

const int controlPin1 = 3; // H-bridge leg 1 (pin 2, 1A)
const int controlPin2 = 4; // H-bridge leg 2 (pin 7, 2A)
const int enablePin = 9; // H-bridge enable pin

void setup() {
 pinMode(controlPin1, OUTPUT);
 pinMode(controlPin2, OUTPUT);
 pinMode(enablePin, OUTPUT);
 digitalWrite(enablePin, HIGH);
 digitalWrite(controlPin1, LOW);
 digitalWrite(controlPin2, LOW);
 delay(10);
}
void loop() {
 digitalWrite(controlPin1, HIGH);
 digitalWrite(controlPin2, LOW);
 delay(1000);
 digitalWrite(controlPin1, LOW);
 digitalWrite(controlPin2, HIGH);
 delay(1000);
}

The motor runs just fine when connected directly to the power supply (where i manually reverse the polarity), but it just won't work properly through the arduino + h-bridge.

I'm quite rookie to electronics, so it might be a rookie mistake i'm into. But halp pls.

EDIT: I realised that when i plug it directly to the power supply the current is around 2 amps, but when i plug it into the h-bridge the current starts out at 1 amp and then decreases. So it might be a current problem, however i do not have any other bridges to test with right now.


texts: Why is the transconductance of a BJT greater than that of a MOSFET?

texts:
During my classroom lectures, I came across this doubt of why the transconductance (\$g_m\$) of a BJT is greater than that of a MOSFET, i.e.:

$$g_{m(BJT)} > g_{m(MOSFET)}$$

It would be very helpful if anyone could clarify my doubt.


texts: Battery Voltage is not as it should be when connected to ckt

texts:
I brought 6F22 9V battery. One's output voltage became nearly 6 volt after some use.But when I connect it with a MCU ckt , It gives only 3.37V as output ( voltage tested  directly from the battery's nodes ).
Then I connect a new battery which gives 9V as output when it is not connected with circuit. But when I connected it with the ckt, it gives around 6.7 V .

=> Why this output voltage of battery changes after connected with the circuit?
As I know Battery is a constant voltage source.


texts: Is power rating of transformer determined by input or load?

texts:
Scenario

I have current carrying conductor with a current transformer around it. If the load is rated at 5V,  2A and only requires 2W of power, but the primary side conductor is carrying 100V 12A.

Question

In this scenario would the power rating of the transformer be determined by the load or the primary side rating. AKA would I need a transformer core rated at 1200VA or 10VA.

Background

I am designing an energy harvesting unit to power my Raspberry Pi

I am aware that regulatory circuitry will be needed, but let's omit that for now. I plan to use a switch mode power converter for regulation, shown in diagram above.

Some proof would be great as I have heard conflicting answers to this question.


texts: Why is my LTspice simulation taking so long?

texts:
I'm simulating an audio amplifier circuit in LTspice, using an opamp and 555 timer, based on the circuit I found here.
This is the circuit diagram and output:

As seen below, the transient analysis is progressing very slowly. I need an audio sample (from the output) of at least 5s. But even after leaving it for 20 minutes or so, the transient analysis only progressed to 3%.
I tried using some commands the LTwiki, but it's not helping much.
I had made this circuit using a BJT earlier. It didn't take too long to simulate then, although the output wasn't that great.
I had built opamp circuits using the same opamp, and it simulated fine. It's just this circuit with the 555 timer.
How do I speed up the simulation?


texts:
I have been taught in my machine's class that eddy current losses are proportional to the square of frequency*flux density, this seemed so fair that I never questioned this. But my machine design book mentions that

  Induced emf = 4.44*freq*Max Flux Density * Area of flux path * No of turns, hence as long as supply voltage is maintained constant, the product of flux density and frequency remains constant even if frequency is changed, and hence there is no change in eddy current losses with frequency.

Now this is also in accordance with emf equation of transformer, at least it seems so, but how is that possible? If that's the case why would we go for high frequencies in eddy current heaters?

I mean, suppose I have source 1 of 230V, 50Hz supplying a coil wound on iron core, now if I replace source 1 with 230V, 100kHz, will the eddy current heating remain same? How that could be the case? Where is my (or book author's) interpretation of equations wrong?


texts: Active narrow bandpass filter with variable center frequency

texts:
I want to make bandpass filter with its center frequency variable(range 50Hz to 5kHz), bandwidth the smaller the better but not less than 50Hz.The bandwidth to be same across the range should be same. Can anyone suggest me an design. I am looking at implementing the following design with 741 http://www.electronics.dit.ie/staff/ptobin/3chapt07.pdf.

Thanks :)


texts: Proteus fast delay scanning problems 8x8 led

texts:
So im practicing shift registers.

Im trying to draw a Smiley Image in the 8x8 LED.

At first, it was okay because I set the scanning delay to 1 second.
but in reality, this must be set to a faster delay (closer to no delay) so that u can see the smiley image permanently.

So I set 10 microseconds for the delay but when I run the program, the smiley image wont appear anymore. Is the program too fast for Proteus software to handle this?

By the way I'm watching this tutorial for my reference and we both did the same thing except I'm using another shift register (HEF4094) with a transistor array(UL2003A). https://www.youtube.com/watch?v=NM7wXta8crM

here is my code:

int dataPin1 = 2;
int dataPin2 = 3;
int clockPin1 = 4;
int clockPin2 = 5;
int latchPin = 8;

int delayTime = 5;

int scan[]={1,2,4,8,16,32,64,128,256};
int smile[]={0,36,36,36,0,66,60,0};

void setup() {

  pinMode(dataPin1,OUTPUT);
  pinMode(dataPin2,OUTPUT);
  pinMode(clockPin1,OUTPUT);
  pinMode(clockPin2,OUTPUT);
  pinMode(latchPin,OUTPUT);

}

void loop() {

  for(int i=0;i<7;i++){
     shiftOut(dataPin2,clockPin2,LSBFIRST, scan[i]);
     shiftOut(dataPin1,clockPin1,MSBFIRST, smile[i]);
     disp();
  }

}
void disp(){

  digitalWrite(latchPin, HIGH);
  delay(delayTime);
  digitalWrite(latchPin, LOW);
  delay(delayTime);

}


texts:
I have a device which has a 16 bit D/A converter which through an analog linear circuit generates an output voltage between -1V and 1V. I have 32 of such channels on my device.

simulate this circuit – Schematic created using CircuitLab

I need to design a circuit to be used for factory calibration. I need to find the gain through the analog part of the circuit so that I know which digital value val to write to the D/A converter to achieve a DC voltage output of, say Vx=800mV.

I need to calibrate it well enough that I can achieve an output voltage of accuracy better than 0.5mV, preferably 0.25mV. The calibration does not have to be very fast. Anything up to two minutes will do.

I have been thinking about just using a D/A converter. Another way could be to use a comparator and a precision voltage reference and using bisection to determine the gain, but it seems to be hard to find one that has an input offset voltage that is low enough.

How would you go about going this?

Conclusion:

I am going to use two 16 channel ADC's and a LTC655BHMS8-1.25 voltage reference which has +-0.025% accuracy at 2 ppm/C. The ADCs will be LTC2439-1IGN which are slow but accurate. Using a small microcontroller I will control the ADCs and use averaging to get rid of noise.

I think this should meet my requirements without breaking my budget.


texts:
I've been thinking about this for awhile so I might as well post the question here and see if anyone knows the answer to it.

I have this type of relay module:

So my question about this relay is:

1) Use the ground wire to the (in)NO->COM(out) for the relay to flow through it when 5vdc is applied?

Or

2) Use the 12vdc power wire to the (in)NO->COM(out) for the relay to flow through it when 5vdc is applied?

And just for the heck of it, I can still use this relay for DC in/output even though it only shows AC in/output on the relay itself?


texts:
I am not a native English speaker so I need a little help to find the right name of the component that I am looking for. I have a device that has a touch panel with 3 touch buttons. They are capacitive touch buttons (cannot be pressed). Below the glass panel (actually it is plastics) there is something that looks like a graphite sponge and below the graphite sponge there is a kind of tactile button which is not a mechanical button but I guess captive (it is flat, cannot be pushed). 4 pins. Other cheaper versions of the device, has the same PCB but has physical tactile buttons soldered instead of this capacitive buttons.

There is nothing written on it, so I am looking for a 4 pin "touch tactile capacitive buttons" that can fit in my PCB. Can you please help me how can search for this touch button.


texts: Li Ion battery issue (voltage appears and disappears)

texts:
I built up a Rspberry Pi self-driving car and everything was fine while I collected data for the Neural Net. After NN finished its training, I want to test the system. At the beginning, everything was fine for like 5 mins. After that the left motors of the car won't work anymore. The first thing I thought about is that at least one of the 2 Li ion batteries I use was drained (I use 2 Li ion batteries connected in series for 2 motors and 2 more for the other motors). I measured the voltage of the batteries, and one of them had 0 voltage. I thought fine I just have to charge it...

Well ... it was not so easy. When i plugged the battery in the cell phone and connected it to the charger, the phone won't turn on (even after 10-15 minutes of charging). Read something about sleep mode of a battery and decided to apply some voltage to the battery (used a pack of 1.5V of batteries). After, I measured the voltage, it was around 2.7. I though good, it helped, let me try to verify the fix using the phone, but it still won't turn on ... Re-verified the voltage and it was 0.0 ...again ...

To summarize, if i connect the Li ion battery to a device that would use it's energy the voltage drops to 0.0, when I apply voltage to the battery, its voltage become something like 2.7V and this behavior is repetitive.

P.S. The other 2 battries seem fine. I have no idea what is the issue. The only way I can think of is to buy new ones, but maybe there is something I don't know. Esp that I need this system working on Monday (morning) and today is almost Sunday (the store I buy from is closed)...

I use this type of batteries: https://www.cnet.com/products/nokia-bl-4u-cellular-phone-battery-li-ion-series/specs/

Any help is highly appreciated.


texts: Part identification, or alternative part - 63 613 Power Management chip

texts:
I have this part, which is the only component that has discernable discolouration, and which I would like to replace:

on the PCB of a non-functioning SMPS (12 V 3 A):

The only markings on it are '63 613' and a search shows up only this: New original power management chip 63513 63 513 63613 SMD 6 foot power IC straight shot, but no data sheets seem to be available (unless I need to be searching for something other than "63613").

Does anyone know of an alternative name/code/identifier for this IC? Or a suitable replacement?

Here is a better close up photo:


texts:
I have disassembled a battery pack for an old (2007-ish) Panasonic camcorder. The battery pack would not charge, so in the interest of pyromania science, I decided to try to learn what's up.

The two batteries from the pack are labelled CGR17360 Li-ion MH12210. I have found http://www.datasheetcafe.com/cgr17360-datasheet-lithium-ion-battery which seems to match.

I measured one of the batteries and it was stable at 2.90v. The other battery was measured at -1.20v, a negative voltage. I verified the label was applied correctly, and I verified I was using the meter correctly.

So the question is: What is going on here? Is there any hope of reviving the second battery?

Does anyone have any experience using these batteries specifically in their projects? If so, anything I should know before going in?

Hints for any of these would be appreciated.


texts: Soldering Alternatives for power cord to PCB

texts:
After this question and this answer I was wondering what are the soldering alternatives for low power applications, like supplied by 4 AA batteries.

I Found online that some use silicon glue and conductive glue as solder alternatives, but do not know if this is applicable on PCB's or not. Also found this but apparently it is for high power applications.


texts: In VFD Drives, DC Bus conditoners are used to protect the DC link supply from transients. Can you please let me know the different scenarios DC Bus of a VF Drive gets these transients and their relation with different drive parameters ?


texts: What kind of filtering does this op-amp perform?

texts:
I am using a heart rate sensor whose schematic is provided here. The circuit uses an operational amplifier (towards the right of the figure) which among other things, does a filtering operation. I would like to get a hint on what kind of filter configuration this is. Specifically, I am interested in the following:

1- Is this an active low pass filter, high pass filter or both?

2- What is the frequency range of this circuit? In other words, what are the cutoff frequencies of these filters.

If someone can provide any relevant hints, that would be great. I would also appreciate if somebody can be point me to relevant resources on this.

The APDS-9008 is a Broadcom package that is a photo sensitive LED with a unity voltage follower and the MCP6001 is a low powered, 1 MHz op amp. Lastly, the 0603 is a Schottky Diode.


texts: Confusion with derivation of average power formula

texts:
I know that average power is equal to \$VmIm/2 * PF\$.

I can show that this is equivalent to \$(1/2)Re(VI^*)\$ by writing VI* in magnitude phase form.

However, I also know that complex power \$S = VI^* = P + jQ\$.

But then P = P/2!

What is going on here?


texts: Symmetrical three-phase power flow problem, √3

texts:
I have done quite a lot of research regarding the power flow problem for the steady state operation of an electric system. In many papers about the power flow problem the power flow equation are referred to as the network equation:

$$YU=I$$

where \$Y\$ is the admittance matrix of the network, \$U\$ the complex vector of bus voltages and \$I\$ the complex vector of bus currents, and the power equation:

$$S_i=U_i I_i^*$$

where \$i\$ is one bus of the network and \$S_i\$ is the complex power in that bus.

Those two equations can be solved e.g. the Newton-Raphson method, when the power equation is substituted into the network equation. However, my question is not about how to solve the power flow problem but about the usage in electric distribution systems with three-phase electric power.

For symmetrical thee-phase power systems, the equation for complex power is:

$$S= \sqrt{3} U I^*$$

where \$U\$ is the voltage between two conductors. This voltage between conductors is always the value referred to, when talking about the voltage level of an electric distribution network. In theoretical literature about electric distribution networks, this equation with the additional factor \$\sqrt{3}\$ for three phase current is always used for the power flow problem, whereas in many papers where the power flow problem is solved the equation is used without the factor \$\sqrt{3}\$. In my opinion, only the second equation is correct for symmetrical three phase systems.

We have developed a program for solving the power flow problem for three-phase electric distribution networks, but we are using the equations above without the factor \$\sqrt{3}\$. We have compared our result to the commercial software NEPLAN and our results are exactly the same. Also in the documentation of NEPLAN the factor \$\sqrt{3}\$ is not used in the power flow equation. I am currently writing my master's thesis and I am trying to write about the theoretical background of the power-flow problem for three phase current and I am wondering why the factor \$\sqrt{3}\$ usually doesn't occur in many papers and why our results are correct, when this factor is not used.

Briefly, my question is, where is the factor \$\sqrt{3}\$ in the power flow problem for three phase electric distrubtion systems? I it hidden somewhere, maybe in the Admittance matrix?


texts: How to load std_logic_vector array from text file at start of simulation

texts:
I am trying to model a memory which shall store instructions for a processor design. These instructions are stored in a text file as 32 bit binary words. At start of simulation all values must be copied into an std_logic_vector array in the memory block from this text file and then a value at a time shall be output depending on the address supplied to the memory. How can I achieve this?

Apparently I need ieee.std_logic_textio.all; along with std.textio.all; and I can only use the read/write functions with variables. If the std_logic_vector array is a signal, it shall not update as soon as I write to it. I am confused on how to do this properly. I won't have any more than 1023 instructions in the text file since I do not want the simulation to use too much RAM.


texts: Multisim - Transient time point calculation did not converge

texts:
I have problem simulating this circuit in Multisim:

(LTSpice)

Here is scheme from Multisim:

When I run transient analysis, I got this:

------ Checking SPICE netlist for Design3 - Saturday, September 26, 2015, 10:58:03 AM ------
======= SPICE Netlist check completed, 0 error(s), 0 warning(s) =======
Transient time point calculation did not converge
Simulation canceled

Any idea what's wrong? Thanks in advance


texts: When I look at the graph of the power in AC circuits versus time (not the average power I am talking about the instantaneous power) it goes from a negative value to positive. On the other hand, I know that a positive value of p(t) represents dissipation and negative power represents generation. How could I link this concept to a sinusoidal form of power? For example, for a resistor that is connected to AC voltage source, the positive power describes the heat that is dissipated, what would negative power in negative cycle represent?


texts:
I am using an HM-10 module (BLE) and Arduino UNO.

My goal is to read data from ibeacons using Arduino and HM-10 module (BLE). Is it possible? I have not been able to find any articles on this. All articles talk about connecting your android phone with arduino. Any idea?


texts: Does VHDL allow port mapping of a single bit output to multiple bits driven to same value, in one line?

texts:
For this hypothetical entity:
entity test is
  port (
    a_out: std_logic
  );
end entity;

The a_out must drive three signals to the same value where the test entity is instantiated. Now one can create an std_logic signal and port map it to a_out and then drive the other three signals from this port mapped signal. Something like this:
signal bit_signal : std_logic;
signal x : std_logic;
signal y : std_logic;
signal z : std_logic;

test_i: test
  port map (
  a_out => bit_signal
);

x <= bit_signal;
y <= bit_signal;
z <= bit_signal;

It would be great if the intermediate bit_signal is not required and the a_out can directly drive the signals x, y, z doing something like this:
test_i: test
  port map (
  a_out => x, y, z
);

I don't think VHDL 2008 allows this, I cannot say anything about the VHDL 2019 though.


texts:
I have a simple question. Can black magic probe be used to do boundary scan?

I couldn't find that it says explicitly that.

If not, what would be cheapest alternative to do that on STM32 (STM32F103) and similar.


texts: I am trying to implement a sequential circuit in logisim that has LED chaser lights (http://www.youtube.com/watch?v=Mo8Qls0HnWo) like on this car. I have tried using D flip flops with a clock and connecting them together and to no avail. Could someone please help me?


texts: Should courtyard information be included in gerber files for manufacture?

texts:
I just used 4pcb's free DFM checker and it doesn't like the fact that the courtyard line widths on my board are 1.968mils (what Altium generated in the IPC component wizard).

It's also complaining about the crosshair line widths, which are 3.937mils (again, chosen by Altium).

Should courtyard information even be included in gerber files for manufacture? If not, why does Altium put it on layer 15, which I thought was supposed to be included when sending files to a fab house?


texts:
I do not know whether this is the appropriate place to post this question but i guess its related to electronics. Basically i'm doing some research on what is the term for "PBCA" in failure analysis?
 (eg As used in this job advertisement )

What does it stand for? And what does it have to do with debugging of board failures?

Thank you for your precious feedback.. I appreciate it :)


texts:
I have two microcontrollers linked together, with the intention of having them talk over serial, as shown below.

12V from the power supply is going into the board on the right. That 12V goes directly from that board to the board on the left (the screw terminals just break out the power coming in).

However, the 7805 (circled in green) gets very hot when that orange cable (a software serial line) is connected as it's shown here. I measure 50mA through it. Disconnecting the orange jumper returns the regulator the a normal temperature.

Is the board on the right powering the board on the left via the serial line? If so, how do I prevent this?

Edit: here is the schematic for the boards


texts:
I want to build a Tracy Island style eyes-that-glow-when-that-person-calls project and I'm looking for advice on what components to use.

For those who haven't watched Thunderbirds, my plan is to have photos of my friends and family up on my wall, each with a small battery powered receiver circuit which, being wirelessly individually addressable, would begin flashing LEDs behind the eyes of the person when a "START" signal was sent from the transmitter with the right address, and likewise stop when a "STOP" signal is sent.

My TV is hooked up to Skype on my htpc and I'm happy hooking up an arduino to it and keeping a list of the receiver IDs and corresponding Skype IDs, so that when someone calls me on skype I can trigger the glowing eyes on the right person.

These circuits won't be activated often. Are there Tx/Rx ICs I could use which power off until a signal is received (I could accept that it powers on when any signal is received, even if it's for the wrong person) so that I can run this from a battery?

The LEDs I'll put behind the photos' eyes won't draw much current and will be blinking for < 10 seconds a couple of times a day at most, so if there is a receiver like that, I could put a battery operated circuit in the frame of the pictures and not have to worry about running wires for power or signal.

How would you recommend setting this up?


texts: Using a micro computer as a macro keyboard device?

texts:
not entirely sure this is the best StackExchange board but I bet some of the great members here could at least point me in the right direction.

I'm looking to use one of the microcomputer devices, like a Raspberry Pi, Arduino, etc as macro keyboard.

What I need to do is plug the device into a Mac via USB and have it be seen as a Keyboard and Mouse. I'd then like to trigger scripts which allow the device to send keyboard presses with specific games between in the correct order.

The device itself needs to be what runs these scripts are it's operating on computers where the OS isn't built yet - it's just automating the initial human interaction we need to do now to create the first account and click through all the menus.

First of all does anyone have a suggestion for which device can be seen as a Human HID and appear to the computer as both a keyboard and mouse (as unfortunately I need two mouse clicks to complete the script) and does anyone know of the software I can run to automate the inputs with pauses etc.

Finally it would be ideal if once the computer is booted I can send a signal back to the device to trigger the next script (I will have loaded a script on the computer at this point to run software) if it could tell the device when it's finished and load a second script that would be ideal.

Look forward to suggestions, thanks in advance.


texts: Why input and output power of chargers don't match

texts:
I know that battery chargers are more than just transformers (they are switched-mode power supplies), still, shouldn't input and output power be equal?
Example:
Input: 110/240V and 1.5A
Output: 19V and 3.42A (65W)
In the case of Input above the power is obviously way more than 65W.
If Input indicates maximums and maximum V and A are drawn, how does the charger dissipate the extra power to meet the Output power demand?


texts:
I've got a Digispark, a Keyboard and a USB Type A Female Breakout.

I've got the following diagram and I've wired up everything as shown in the image:

However, when I plug in the keyboard to the USB Breakout and the Digispark to the computer, the keyboard's LED does not turn on (it's supposed to be turned on 24/7 by default).

What am I doing wrong?


texts: How do I drive a 5W low-pressure mercury UVC bulb?

texts:
How do I determine the voltage and necessary power supply for this bulb?

This bulb is a UVC low-pressure mercury vapor bulb used in my air purifier. It fits in a G23 Socket; normally I would expect a compact fluorescent bulb (G23) to have a ballast built in. This bulb is incandescent but it fits into a fluorescent socket. How do I drive this bulb, I'm assuming I need some sort of ballast?

Note: I believe this bulb is the old-style bulb which, according to some references, is considered incandescent but admit I do not know for sure. It does contain a filament.

  An older design looks like an incandescent lamp but with the envelope
  containing a few droplets of mercury. In this design, the incandescent
  filament heats the mercury, producing a vapor which eventually allows
  an arc to be struck, short circuiting the incandescent filament.

from Wikipedia


texts: Best way to convert a voltage output from a circuit into graph software

texts: Looking to convert a voltage output from a circuit in order to show a voltage/time graph. From my knowledge I would have thought the best way to transmit the data would be to use the mic input on the computer because it would just be a series of pulses (specific circuit) or something using a USB interface. Can anyone guide me or have any better ideas?


texts:
I'm a sewing machine mechanic, trying to increase my electric motor knowledge.
I have a Bernina 830 sewing motor where the carbon brushes ran down and the wire damaged the commutator and ran a groove in it. The motor was smoking.

I took it apart, I sanded the commutator so it was nice and smooth, cleaned it all up etc. The capacitor was split and was leaking so I removed it (Bernina advised the capacitor is obsolete and the machine should be run without it).
However, it is now sparking a lot and after struggling for a while it kind of popped with a flash and just stopped.
What I think are the field coil wires are covered with a fine plastic film insulation, however this has perished in places.
Could this be causing the issues, and if so what's the best fix?

Update. This is the other end. It's melted on one side only. Looks very poorly.


texts: How to model MPPT technique with PID controller

texts:
I need to model a MPPT algorithm with a PID controller at Simulink. The model will feed the gates of two mosfets of a push-pull converter.

I have to extract max power from PV and have a fixed voltage(400V) at the output of push-pull converter even the irradiation decreases. I probably use incremental conductance or P&O algorithm for MPPT but i haven't decided yet.

I have read some papers about this and acording to them, i need to measure Vpv and Ipv from panel and put them into a "something"(matlab fuction, or a different type algorithm) then output of this "something" will be referance voltage and finally give this referance and feedback from converter output into a PID controller and produce a duty cycle for mosfets.

I understand the concept but i don't know how to write the code or model the algorithm which transform the Vpv and Ipv into referance voltage.( i mean the relationship for this change, because the panel output will be like 35 V and the output voltage should be 400V)
Also i want to ask what load should i use for having fixed voltage at the output of converter? (I may model the load as if it is DC bus with constant voltage and according to power the output current varies but again i could not figure out how to do)

I am using this as my final project at university and so far couldn't get help about it so i will be appreciate any help.


texts: How calculate the transfert function of boost converter with input capacitor?


texts: Why do magnetic disks not have multiple heads per disk?

texts: So it seems to me that when trying to improve performance of a external memory device (HDD), the thing that is increased is RPM. Why not have multiple read/write heads per substrate instead of just increasing the RPM? Is this due to the formatting of the data or simply because heads are expensive?


texts: How to power a DC brushless motor without a speed controller

texts: I have a brushless motor but It doesn't power directly with a 9 volt battery, but I don't have a speed controller what else can I use to power it.


texts: Why do ADCs use 10 bit rather than 8 or 16?

texts:
Why is it that most ADCs, like the ones on the Arduino, give 10 bit resolution rather than 8 or 16 bit?

It just seems wierd that they don't match standard data sizes, particularly on integrated ones.


texts: 71 RBG LEDs, 3 transistors, and 1 ATTiny85

texts:
I am trying to design a circuit to control a total of 71 RGB LED's (wired basically in parallel for each color channel) using an ATTiny85 to control the on and offs for each color channel. I figure that the current load will be way too much for the ATTiny85 to be directly connected to the LED banks since it max's out at about 40mA per channel.

My thought would be to isolate the LED color banks each on their own transistor. Then I would just connect the bases of the transistors to the ATTiny85's output pins.  I figured that this configuration would save me programming for a LED Driver IC.

Does anyone have an input on this evil plan?  Also,  would a regular 2n2222 appropriate for that?


texts:
I'm trying to think of alternatives to transistors, simply because I'm curious. I don't care so much about the amplifying characteristics of transistors as their ability to make logic gates. Here's what I've got so far, could somebody please add to my list?

Vacuum tubes: duh

Relays: Normally closed relays are all you need to make any logic gate. Normally open relays are also useful.

Mag-amps: Magnetic amplifiers could be used to make logic gates similarly to transistor-transistor logic.

Ferrite Toroids: It turns out they can be used to do logical operations, but they can't be used quite like normal logic gates. http://www.youtube.com/watch?v=nQXjm7ru--s