texts: Second order active low pass filter values

texts:
I want to use a second order active low pass filter to cut off frequencies over 33kHz . The input is 1.3 Volts peak to peak sine wave of 32 Khz and I want to make it 30kHz of 1Vpp . The formulas for calculating the values on the components of S.O.A.L.P. are for different SOALP than mine . Can someone provide me with the formulas that I need to calculate the values of my schematic or better provide the values and explain

Edit: the op amp is provided 20V in the [+] wire and is grounded on the [-] wire

Edit 2: the formulas I found for other SOALP are on this link
http://www.electronics-tutorials.ws/filter/second-order-filters.html


texts: How to choose a substitution transistor for a feedback amplifier?

texts:
I'm experimenting with RF feedback amplifiers (this topic is well covered in "Experimental Methods in RF Design" book, if anyone would like to know what that is). Particularly I'm interested in finding inexpensive transistors available in local shops with high fT to build amplifiers with flat frequency response. Well-known 2N3904, 2N2219A have fT = 300 Mhz and it's hard to build a broadband feedback amplifier using them.
I've discovered that 2N2369A and it's Russian equivalent KT3142A both have fT = 500 Mhz, don't cost much and work well as a substitution for 2N3904.
As a substitution for 2N2219A I decided to try 2SC5694 (Ft = 330 Mhz, datasheet [PDF]) and 2SC3953 (Ft = 400 Mhz, datasheet [PDF]). The following circuit was used for testing:

(As a side note, I know it's not matched well to 50 Ohms. It's input and output impedance is closer to 25 Ohms and is a little reactive. However this circuit is used as a second stage of three-stage QRP power amplifier, similar to one used in Summit Prowler 6B and Summit Prowler 7 transceivers by Paul Taylor, VK3HN. The third stage is not quite 50 Ohms either, and 25 Ohms impedance of this stage gives a better frequency response of the entire PA than a "right" 50 Ohm stage. I've checked.)
Here are frequency responses of this stage with 2N2219A (yellow), 2SC5694 (purple) and 2SC3953 (blue):

2SC3953 flattened the frequency response because of the higher fT, just as I was expecting. But surprisingly 2SC5694 worsened the frequency response. Also the SWR rised from about 2.0 (which is OK for a 25 Ohm stage) to almost 10. I though maybe the transistor is damaged or I made a mistake during soldering. So I resoldered the circuit with another 2SC5694 and got the same result. I also tried to drive this stage with -5 dBm, almost as it would be in a real PA, instead of -20 dBm, but it made no difference. After changing the transistor back to 2N2219A everything works fine.
I'm not that long into homebrewing and apparently I don't know something about NPN transistors, or missed something while reading EMRFD. This is the first time I've encountered such behavior. Could you please explain what causes it? Which parameters of the transistor I should be more mindful of next time?


texts: Scanning for discoverable bluetooth devices with Arduino

texts:
I'm looking to be able to build a kind of course location based system where a mobile Arduino will scan for a list of currently visible (discoverable) bluetooth points, and then depending on pattern matching will do work accordingly.

Does anybody know of how this might be achieved? The bluetooth shields and bluetooth version of Arduino seem to just be endpoints for attaching to the serial of the Arduino itself. Does anyone have experience with this?


texts: How negative feedback increases the bandwidth

texts:
Negative voltage feedback affect all the frequencies equally. Hence by simple observation it is clear that, negative feedback doesn't affect the bandwidth of the circuit.
But in many books, it is written that negative voltage feedback increases the bandwidth of the circuit.

Can you explain how negative feedback affect the bandwidth ?


texts:
I need to build a soft latching on-off-on switch that latch with momentary push buttons for use in on a 220v AC power line.
I mean a switch that have three momentary push buttons (2 buttons for on state and one for off state).
Is there a schematic for this?

Thanks


texts:
How / can you connect Ethernet devices together without magnetics? How do you wire it up? What sorts of practical limitations are there on doing this?

To clarify, I'm not trying to connect two computers here. I'm thinking specifically of creating a small network of microcontrollers on a single board. Lets say the total length of a network segment is no longer than 6 inches. This would be for 10BaseT or at most 100BaseT.


texts: On PIC18 series, when should I use LAT register and when PORT?

texts:
I'm programming a PIC18F4680 using mikroElektronika's mikroC PRO compiler and I've set the LCD library to use following ports to communicate with LCD:

// LCD module connections
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;

sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
// End LCD module connections

and the LCD is sometimes displaying garbage. I was told to LATB instead of PORTB registers and after reading the I/O Ports section of the datasheet, it's still not clear to me when I should use PORT and when LAT registers.


texts: Why harvesting energy why not harvesting power?

texts:
I am wondering why is it called Harvesting energy and why not harvesting power? Energy is measured in Joules/s and power is Watt but the result is watt. For example if we harvest energy from sun or from wind or from heat or from vibration all of these energy sources gives a output in the form of Volt and Current. So basically what we get is power.

So why don't we call harvesting power from sun or from other sources of energy?


texts: Thermocouple differential output to thermocouple input

texts:
I have a controller with two k-type thermocouple inputs. I'd like to have one of those inputs be the difference between the two TCs. Since TCs are voltage devices, it looks like an opamp would be perfect here. Maybe three: one for each TC, then one to compare the two signals and send the difference to the TC input. I've just never cared about microvolt levels before. Would this work?

The temperature ranges I will be measuring will be from 20C to 200C, they will never be negative.

I also need to have one TC still connected to the controller, so the circuit diagram below won't work for me, I don't think.

The controller is Japanese from 1997 and has no manual.  It has K-type inputs.


texts: Impedance of differential inputs on AD converters

texts:
I'm currently trying to attach a rather fast ADC/DAC-converter chip to an FPGA to receive and transmit RF in the future, but getting the converter to run and attaching a signal generator and an oscilloscope for testing is my main goal right now.

I'm coming from the digital world. I did all kinds of digital circuits and used an AD converter for easy tasks with a microcontroller, but when it comes to analog high speed signals which are differential and sensitive to several factors like impedance and so on, I have basically no idea what I'm doing.

The chip I want to use for this project is the AD9862. It's rather old but they are not very expensive, easy to solder, and they have been used by Ettus Research in several models of their USRPs which I'm using as a reference platform. If you have a suggestion for a better chip, please tell me!

Now the main thing I'm concerned with is the whole analog domain. The AD9862 has 2 differential inputs which can be optionally buffered (which is what I should do, right?) and the datasheet says the input buffer has a constant impedance of 200 Ohm. Now what I want to do is, just take those two AD-channels out to an unbalanced SMA connector with 50 Ohm impedance to connect a signal generator or a radio frontend later. So, I need a Balun for that.

Ettus did that too. They have several daughterboards which you can attach to the baseboard to have different frontends connected to the AD-/DA-Converter. Now, if I look at the BasicRX Daughterboard (was: easiest daughterboard) which does exactly what I want, I see that they are using a Balun called ADT1-1WT. If I look that one up, the datasheet tells me, that it has an impedance of 75 Ohm. Isn't that totally wrong? I thought I need a 50 Ohm unbalanced to 200 Ohm balanced transformer.

Also the input is terminated with a 50 Ohm resistor and the output which goes, directly without any more components except a connector, to the AD (VINP_A/VINN_A and B) is series terminated (right? Or is that a low pass filter with the 10pF capacitor? I read on a mailing list somewhere that the values for a low pass filter are wrong in this schematic BTW) with 50 Ohm. That doesn't match at all with the 200 Ohm input impedance of the AD input. It would be awesome if somebody could explain that to me! For me all of the values are totally off.

Also, what about the traces on a PCB? They also need to have the right impedance to prevent reflections and standing waves. So I need to match them, I guess? So the output of the balun should be differential traces with a differential impedance of 200 Ohm going to the AD input and on the other side of the balun, I need a 50 Ohm trace going to the SMA connector?

If somebody could shed some light on this for me, that would be awesome! These are all things you only seem to learn at university if you take electrical engineering as a major and I took computer science and this is all just an amateurish hobby for me, so I'm kind of lost right now :(


texts: Does wiring a multi-cell battery pack to provide two different voltages adversely affect cell lifetimes?

texts: A robot-arm kit I am playing with uses 4xD-cell batteries wired in series to provide 6V, with an additional connection on the cross-bar at the end of the pack to provide 3V. This seems reasonable enough, but I wonder if it might have any effect on cell lifetimes?


texts: Battery initial state of charge after charge/discharge

texts:
I'm trying to estimate the initial state of charge for my battery (NiMh 9.6V @ 3300mAh) using the open-circuit voltage - state of charge discharge curve. I use an IC that measures the battery voltage/current and has coloumb counting capability.
The problem I'm having is estimating the inital SOC e.g when the SOC is 42% (~9.2V) and I charge the battery for 1 hour at 75mA, the actual capacity increases by 2% to 44% SOC however the voltage jumps to 9.6V which is considered fully charged. If I now estimate the SOC using the ocv-soc discharge curve, the SOC will be 100% which is wrong.
The situation I have requires me to use a voltage-based estimate to get the initial state of charge when the system starts up so I cannot use coloumb counting here.
How do battery fuel gauges use a measured battery voltage after it was discharged/charged to get an initial estimate of SOC? Do they plug the voltage into some kind of "resting" model?


texts:
I am working on a Data Acquisition project using Arduino Due for petrol scooters where I am trying to collect 6 types of data - acceleration, location, brake, throttle, horn and RPM of the wheel. I'm using the BNO055 9 axes IMU shield to collect acceleration data, GPS shield to get location, and a 44E hall effect sensor + magnet to collect RPM data. I am pulling the hall effect sensor using INPUT_PULLUP command in the IDE and not using an external resistor (I hope that's okay). The throttle data is directly given to an analog pin on the Due (I'm using an electronic throttle which has a hall effect sensor inside it). For the brake and horn (it's a mechanical horn), I am using a potential divider that gives an output of 3.3V, to give it to the digital pins (I am recording the instances at which the brake and horn is pressed). The Due is being powered by the 12V lead acid battery on the scooter. The throttle and the hall effect sensor that I'm using for RPM is powered by the 3.3V onboard regulator on the Due. All the data is logged on the SD card at a frequency of 5Hz. I am facing a certain issue with the horn and RPM data, and here it is -

Every time I press the horn, the RPM data goes boink. Even pressing the indicators corrupts the RPM data which is weird, as I am not even collecting indicator data. The more I press the horn, the more crazy the RPM data goes; sometimes it touches 1000-2000 RPM which is absolutely wrong. But when I dont press the horn, I get the correct RPM data. Why is this happening? Why does the horn affect only RPM data? Is it because, the hall effect sensor works on magnetic field and the horn is an inductor which generates a huge amount of magnetic field? Or, because the Arduino and the horn are powered from the same source and hence have a common ground? Is there a way to isolate or filter the noise from the horn?


texts:
Goal: Trying to measure low-frequency noise such as 1/f noise spectrum from a material

What other people did: apply a DC current source --> take the voltage across the material --> amplify it with a preamp --> into a FFT spectrum analyzer

In my case, the problem is the noise is relatively small compared to the DC component, and the amplifier can easily get overloaded by the DC offset before amplifying the noise to a reasonable level. But if I use a DC block, the low cut-off frequency is still not low enough. For 1/f noise, I would like to measure down to 1 Hz. Can anyone suggest a way of doing it? Thanks.


texts: How to calculate cutoff freqeuncy of Bandpass filter, given an attenuation dB level (OTHER THAN -3DB)

texts:
I know that -3dB is the accepted standard, where the power of the signal is at 50%, and that upper and lower cutoff frequencies are calculated with regards to this value, and there are simple formulas for doing so (at -3dB).

However, I would like to calculate such cutoff frequencies for different levels of attenuation (say -1dB, or -2dB) mathematically, without graphing the response.

Thanks for your time and input.


texts: For one of my project I need to shutdown my system when my Li-ion battery reaches 3V.But I want to know if I can use this type of component : http://www.farnell.com/datasheets/11601.pdfhttp://www.farnell.com/datasheets/76549.pdfhttp://www.farnell.com/datasheets/11603.pdfFor detecting the battery voltage and disabling my LDO? I know they are designed to be used for the Reset of microcontrollers.But it should work just fine by using one of those three no?Thank you in advance !EDIT :I first wanted to use the TC54 from Microchip which is designed for this purpose but it seems to be obsolete...I also need the system to be through hole.. This is why I don't use a battery protection chip, because I could not find one..


texts: What does the flange do over that rectangular cavity antenna?

texts:
I'd like to know what does this flange contribute to the rectangular cavity just below the flange.
I assume it's to reduce side effects, what else are the contributions the flange does to the cavity?
What's meant by infinite flange and finite flange?
Thanks in advance


texts: What is the "collector light current" of a phototransistor and how does it relate to the collector current?

texts:
I found the "collector light current" term in this datasheet (Vishay TEFT4300) but I can't find a definition for it on the internet nor figure out how it relates to the collector current.
I am particularly interested in this graph below:


texts: Do I need to measure impedance before every CAN termination?

texts:
Background: I need to set up a CAN bus between different components of an electric UAV (battery management system, motor inverter, autopilot, etc.). My avionics/networking experience up to now includes home networking, RC hobby servos (PWM), and "smart" hobby servos (serial), so I'm familiar with the general process I have to follow in terms of network software (device IDs, baud rates, etc).

Problem: I've never dealt with the idea of "termination". I keep reading something along the lines of "CAN needs 120Ω termination at each device".

This video helps me understand why I need termination, but I'm not sure how to implement that.

Am I supposed to slap a 120c resistor parallel to the CAN_H and CAN_L pins of each device?

OR

Should I measure the impedance of a length of desired wire length and match that impedance?

For example: I need 75 cm of wire between device A and B. I've set CAN bit rate to 250 kbps. I connect 75 cm of wire connected to a signal generator supplying a square wave at 250 kHz and measure an impedance of 75 Ohms. I terminate with a 75Ω resistor.

Followup questions:

Do I need to terminate at both ends of a connection?
Is there a hand-held tool for measuring impedance at a set frequency?
What is the recommended way of connecting a wire branch from the main CAN line to a set device? Solder?


texts: Where might I find a weird hybrid USB A-MicroB plug?

texts:
I have a product with a USB-A plug that can open to reveal a Micro-B plug:

Any idea how or where to find such a thing?  I tried searching Mouser and Digi-Key but don't see anything like it. (Actually, I would like to find a USB-A/Type-C hybrid, if such a thing is even possible mechanically, to avoid including illegal C-to-A adapters with products.)


texts: How does this passive resistor network separate HS and LP signals from MIPI inputs?

texts:
I'm currently trying to interface a MIPI camera with my FPGA, a 10M50 on an evaluation board.
The following schematic is taken from the documentation of the board and show how MIPI differential signal is receive by the board and split into 1 High Speed (HS) LVDS and 2 Low power (LP) CMOS signals.

I'm trying to understand how this montage can separate the two signals and apply level-shifting.
I have found a similar montage in this documentation: AN 754: MIPI D-PHY solution with passive resistor network
From what I understand of MIPI communication, the differential pair switch from LP for control (around 1.2V) and HS to transmit data (around 200mV). The I/O ports of the FPGA are unable to read the HS signal as is, so it need to be shifted to a voltage domain corresponding to the FPGA.
Input range from around 200mV (in HS mode) to 1.2V (in LP mode). On output side, HS is around 1.2V and LP are at 2.5V. see the MIPI receiver part in: MAX10 Evaluation Kit User Guide
Can anyone enlighten me ? Thanks in advance.


texts: Simple current transformer strange waveforms

texts:
I'm trying to build simple 50Hz current transformer (just to see the mains current - maybe some microcontroller measurment in the future) following the answer to  this question.
When I connect it to a 100W 240V light bulb (incandescent) the output sine wave is perfect.
When I connect an SMPS (laptop charger) I get this strange waveform:

What is mostly strange for me is indicated with arrows. Why is that? Shouldn't be this flat after a peak?

This is a photo of my setup:

This transformer is just small one (8W?) took from plugpack charger of some kind - 12V output. I'm measuring the waveform on its original primary side, loaded with 9kOhm resistor (two 18k in parrallel.)
Why is this waveform so strange? Is this transformer constuction ok? Maybe the inductances are too high/low?
EDIT
As Andy Aka suggested - I reduced the loading resistor value to 10Ohm. The waveform is now flat between peaks (as it should be), but the overall amplitude is very low - 20mV for 100W incandescent ligth bulb. Can I somehow increase the amplitude, or just add an amplifier?
What I tried to increase amplitude: I wound another 10 turns with thinner wire and connected this loading resistor there, now completly no voltage appeared on it, but according to the transformer formula, it should be quite large. Iout = Iin*(1/Nsec). For original primary N was like 2000 or so. Why then there is no voltage across this resistor?


texts: "DC" Impedances seen looking into terminals of a BJT

texts:
Our professor in college was making us understand the stiff voltage-divider bias concept of a BJT.

simulate this circuit – Schematic created using CircuitLab

(Ignore the resistor and voltage source values)
Here he says, "The voltage-divider can be called/assumed a "stiff" divider if the current through R1 and R2 is quite large compared to the current going into the base (which makes sense ofc). Such an assumption can be made if the resistance seen looking into the base is much larger compared to (R1+R2), which ensures very less current flowing into the base".
How do we measure this resistance looking into the base at bias conditions? I can understand and calculate small signal impedances no sweat, but this confused me idk why. Or for that matter, how would we calculate the impedance looking into any of the terminals at DC? Any kind of hint will help. Thanks!


texts: Can you use a vfd to run a capacitor start motor?

texts:
I've read on many forums, publications and specification sheets that it's not possible to run a capacitor start motor using a VFD. The start winding of such a motor is momentarily powered until the motor achieves full speed. Leaving it powered, will cause the start winding to overheat. Consequently, a VFD can't power such a motor because of the capacitor has been selected for a given frequency of 60 Hz.

Is it possible to add another circuit between the motor and VFD to power such a motor? I can see removing the start capacitor and connecting it directly to another three phase leg and then use a circuit to detect the back EMF to disengage the start winding. Is 120 degree phase difference sufficient to start it?


texts: Need to convert 0-10VAC (alternating current) to 0-3.3VDC (direct current)

texts:
I am using a sensor that outputs a 0-10 VAC (alternating current) and I need to convert this signal into a signal within 0-3.3VDC (direct current) to feed into an ADC.

What is the best way to go about doing this?

Is there an integrated circuit/breakout board that will take care of this conversion?


texts: Why does TI have so many microcontrollers?

texts:
I am working on a project with a group and I am responsible for the digital part of the project, so I will be writing the code. To go from Analog to Digital, I have to choose a microcontroller.

I was looking at TI microcontrollers and found that they have so many. They have:

Stellaris
Hercules
MSP430 Series
And the list just goes on..

My questions:

Which micro controller does one use and why ?
Under what conditions should I use microcontroller X rather than Y ?
Why are there so many different micro controllers?


texts: Guitar amplifier repair: burnt fuse, capacitor, what else?

texts:
A friend has asked me to take a look at his guitar amp: Peavey Valve King VK212.
Problem: suddenly the amp stopped working during operation and the status lamp went off.
First reaction: fuse replacement, the status light came back but zero sound.
This is my starting point and observations (full schematics are easy to google, I have doubts if it would be fine for me to share, though):

Fuse F201 clearly burnt, but continuity tester shows flow on both sides! Obviously short circuit is somewhere around. Resistance measured on bot ends of the fuse = 14 ohms. This confirms the fuse is dead and flow is another way.
Capacitor C201 looks slightly damaged, I bet it is short circuited and blew the fuse.

Now two questions to experienced colleagues:
Q1: I localized at least these two faults. How far do you dig to avoid cooking the parts directly after replacement? I mean is there a rule of thumb to say "ok, I got to the root cause, can do the replacements and switch the thing back on". Ideally I should probably check the whole module but it means soldering quite a few parts out of the circuit to measure them... But maybe at least the diode bridge that follows right after?
Q2: Basically all plugs on the plate are additionally glued. Is this because of the guarantee, or is this to make sure they hold despite vibrations of the amp? Basically I would like to know if I should glue them again after the repair.
Thanks in advance for any hints!


texts:
I'm a Beginner, So I don't know much about this. Please correct me if I'm wrong.
I have downloaded platform files and firmware files. I'm using ChipLoad to flash.
This is the output I get when using COM6, and as per the schematic, it is HCI UART.
@E,003B,BOOT,E=01010E06,S=05020016,P=0103,H=D1,C=00,A=E45A59737646<CR><LF>
@E,000E,ASC,S=01,R=03<CR><LF>

I have connected the board correctly. But still, it fails.
Commands Tested:
ChipLoad.exe -BLUETOOLMODE -PORT COM6 -BAUDRATE AUTO -NOVERIFY -MINIDRIVER uart.hex -BTP CYBT_343026_EVAL_SFLASH.btp -FIRMWARE ezserial_343026-CYBT_343026_EVAL-rom-ram-Wiced-release.hex

Trying baudrate 115200   Conn: PORT=COM6    BAUDRATE=115200
Trying baudrate 3000000   Conn: PORT=COM6    BAUDRATE=3000000
Downloaded 0 code bytes ( 0.0%) and 0 data bytes ( 0.0%). Verified 0 code bytes ( 0.0%) and 0 data bytes ( 0.0%).   Current state: Terminated with error

ChipLoad.exe -BLUETOOLMODE -REBAUDRATE 115200 -PORT COM6 -NOVERIFY -MINIDRIVER uart.hex -BTP CYBT_343026_EVAL_SFLASH.btp -FIRMWARE ezserial_343026-CYBT_343026_EVAL-rom-ram-Wiced-release.hex

Downloaded 0 code bytes ( 0.0%) and 0 data bytes ( 0.0%). Verified 0 code bytes ( 0.0%) and 0 data bytes ( 0.0%).   Current state: Terminated with error
Failed to execute HCI Reset

ChipLoad.exe -BLUETOOLMODE -REBAUDRATE 3000000 -PORT COM6 -NOVERIFY -MINIDRIVER uart.hex -BTP CYBT_343026_EVAL_SFLASH.btp -FIRMWARE ezserial_343026-CYBT_343026_EVAL-rom-ram-Wiced-release.hex

Downloaded 0 code bytes ( 0.0%) and 0 data bytes ( 0.0%). Verified 0 code bytes ( 0.0%) and 0 data bytes ( 0.0%).   Current state: Terminated with error
Failed to execute HCI Reset
```


texts:
I have a circuit of the following form.

Circuit diagram:

How do I decide the resonant frequency ?

What is the criteria here to select the resonant frequency ?

Background: I am testing the transfer function for the system, and I need to know what is the proper value of "w" (omega) I can use.

Please let me know if anyone has the knowledge on this.

Thanks.


texts: I am trying to output a video signal with a slow microcontroller (Arduino). I don't need anything fancy like HD or 30fps, and if it takes a second to update the frame that is fine. I was looking for video protocols that have a clock line instead of requiring fast and precise timing. I would ideally like just a red, green, blue, clock and ground line, that works at any speed. Does this exist? HDMI, VGA and composite seem to have set of required clock speeds that are far too fast for my use.


texts: Do eeprom page writes always cost the same time as byte writes?

texts:
Some EEPROMs provide the possibility of a multi-byte write.

For example, the AT24C provides an 8-byte page write besides the classical single-byte write.

The datasheet specifies 5 ms as "Write Cycle Time". However, nowhere is it said that this is true for both types of write instructions. I would infer that it's the same, although it is never explicitly stated.

Can one safely assume that it takes the same time? (excluding, of course, communications overhead in case of external chips)

Can this be answered generally for EEPROM (which is strictly EEPROM, not something emulated in flash), instead of only for the product mentioned above?


texts: What is good / proven / low-cost bluetooth module, preferably with open source driver software, for getting data back and forth between my microcontroller and smartphone (either Android or iPhone)? Can you provide good general purpose examples and resources for interfacing phones and microcontroller using bluetooth?


texts: Is a D Type Edge triggered Master Slave flip flop considered a 1bit memory cell?

texts:
So in class we talked about how a D-type edge triggered flip flop is considered a 1bit memory cell. I think this is the same for a D-type latch.

My question is, since a D-type edge triggered master slave flip flop uses 2 D-latches, is it considered a 1bit memory cell or 2bits since it has 2 D-latches? And if it is, if I wanted to theoretically create a 1MB memory module entirely out of master slave flip flops, would I just take 1MB and divide by 2 bits(or however many bits the flip flop has)?


texts:
Will this work?

Proposed principle of operation:

R-C oscillator starts resonation of coil and capacitor.
The R-C oscillator is overriden by the induced voltage.
The frequency is dynamically adjusted.

(I'm sorry that the circuit is not straight- hand drawn never is.


texts: What could this IC be? Trying to reverse engineer a board

texts:
Studied EE, haven't used it in 10 years, so pretty rusty.

Part 1: the board and how it's connected

I'm looking at a very simple current controller that drives 3 different current levels based on a switch. Here's what the board looks like on the back,

On the left side, the "W" is the ground to the battery, "R" is the power, which is 7.5V, and the "B" is connected to the load - I'll explain this later.

The other side of this board is just 4 sets of resistors & LEDs that light up to show which setting you're on. No need to draw those.

Here's a picture of how it's connected (more or less), and I'm confused about exactly how U2 works.

Of course they scratched off all the markings on the ICs so we'd have to guess what they are.

Part 2: my take on this board

Here's my guess,

U1 is a voltage reference, it's always at 3.3V even when the
battery's voltage fluctuates.
U2 is an op-amp of sorts, but this is where I'm not sure because of all the weird connections.
Q4 is a MOSFET that drives current.

So it should be pretty simple, it's an op-amp that feeds in a variable voltage into the gate of the MOSFET that drives a variable current.

If I were to design my own current driver based on what's on this board, it'd probably look something like this,

This is pretty simple, got an op-amp with a negative feedback circuit. You put a switch on the positive+ input of the op-amp that switches between different sets of resistors and you get different sets of voltages on the output depending on the gain, which then drives the MOSFET.

"W" would be ground, "R" would be the 7.5V above the load, "B" would be the point below the load at the drain of the MOSFET.

Part 3: what I'm confused about

What exactly is U2?

Here's what I do know.

It has 8 pins, OK.
Top-left pin is power, 3.3V. Top-right pin is ground, OK.
Second-left pin is output, feeds right into the gate of the MOSFET
(Q4), OK.
Second / Third / Fourth pin on the right side toggles between the 3 current settings. For any one setting, one of these pins is at one of three voltages (0.37V, 0.15V, 0.19V), and the other two are at 3.3V - just open-circuits.
The last two pins on the left do not seem to do anything or really connected to anything that matters.

What is U2? Why does it have no feedback? Maybe it's not an op-amp IC at all?

Part 4: my 2 questions

What is U2?
Is the circuit I created (the third image) basically right?

Thank you!!!

ADDITIONS

Sorry for not posting the actual photos.

Here's the back side (with all the ICs):

Here's the front, with the big switch button in the middle, and 3 sets of 4 resistor+LED combinations each.


texts:
I'm programming a PIC16F77 with ProPic 2 which communicates via serial port. As I don't have this port in my PC, I used serial to USB adapter. I'm using ICProg in Windows 8.

I've proggrammed it before but it was in Windows XP using the driver who specifies in http://www.ic-prog.com/index1.htm and worked perfectly. But in this OS the only difference is the adapter, the program gives some errors while loading the driver:

  "Error occured (Access is denied) while loading the driver!"

  "Privileged instruction"


texts: How to choose coefficients to compute surface LaPlacian filtration of analog sensor data?

texts:
Surface LaPlacian filtration is used (among other things, probably) to improve spatial resolution of analog sensor data, particularly in the context of electroencephalogram (EEG) and the magnetoencephalogram (MEG). I'm trying to use it with my EEG development board in pre-processing for an algorithm that controls a drone's movements.

In several brain-computer interface (BCI) and EEG data pipeline programs (like OpenViBE, Brain Bay, or even the Processing IDE) you can add such a filter to the data pipeline. The only parameters you're asked to provide are hard-coded coefficients.

All I've been able to learn about these coefficients thusfar is that there are 2 per input channel (i.e. 2 per input analog sensor data streams).

Note in the example photo above I've selected only 4 channels but there are still enough coefficients for 10 channels.


texts: Charge mode piezoelectric signal conditioning

texts:
I have a charge-mode piezoelectric dynamic pressure sensor (datasheet link) that I want to read a signal from. If you look at the datasheet it says the sensor outputs are in a balanced and floating configuration, which I think means its output is a differential signal. Since it is a charge mode device, I will need to use a special charge amplifier to condition the signal to a low impedence voltage mode signal.

So I have two question related to this topic:

Is there any reason why I can't or shouldn't treat the output of this charge-mode sensor as a single-ended signal by tying the negative pin to ground? This would allow me to use a coaxial cable for the connection between the sensor and my charge amplifier. The charge amplifier that I currently have is only meant for RSE signals, so it's input connector is BNC.
Are there any benefits to using a differential signal over a balanced line rather than a single ended signal running over shielded coax?

This sensor will be operating right next to a DC generator, so it will be an electrically noisy environment.


texts: Does guitar pickup absolute polarity matter?

texts:
I have a Telecaster which has a phase issue in the middle position, because the bridge pickup is wired backwards (the hot output to the ground). This hot grounded output is also used to ground the bridge and strings.

To fix that phase issue, I can:

Reverse the polarity of the bridge pickup, and disconnect the bridge ground from the hot output and connect it to the guitar ground. Both pickups will be wired "forward", with the hot to the output.
Reverse the polarity of the neck pickup, so that both are "backwards" (hot to ground).

The base of my question (to pickups specialists) is: if two pickups are both wired backwards, does is sound the same as if they were both wired forward ? The ear is not sensitive to absolute phase, but devices in the path might be ?


texts: How to solve a simple diode gate question from Sedra and Smith (Exercise 4.4)?

texts:
This question asks me to find the current and the voltage. I get the general idea behind diodes so far; if you apply a positive voltage across it, then the diode becomes a short circuit, and if you apply a negative voltage across it, the diode becomes an open circuit.

With this question, I'm just not sure how to deal with the fact that there's three different voltages going in, and how to use that to calculate the I and V. Furthermore, say I applied an input voltage of 0 Volts to all the inputs of the OR gate. How do I know whether the voltage across is positive or negative to see if it conducts? Can I use the fact that there's ground linked with the resistor somehow to calculate this? Same idea with the AND gate. I know that if the voltage is HIGH on all three inputs, then the output voltage stays HIGH at 5 volts as well. But why? How do the inputs being HIGH make the diodes open circuits or closed circuits?

It seems like such a basic concept, but I might be overthinking it and confusing myself.

I did find basically the same example I have linked here over here: diodes exercise logic gates? but I don't get why the 3 Volt is the correct? Aren't they all positive relative to the resistor and ground, so they'd all be conducting? I'm not sure

As a further edit, the second response to the question I linked in the previous paragraph is this:

  In the left diagram, the diodes connected to 1 & 2 volts are
  reverse-biased and so the only current flowing is from the 3 volt
  source.

  In the right diagram, the diodes connected to 2 & 3 volts are
  reverse-biased and so the only current flowing is into the 1 volt
  source.

How does one figure out that some of these diodes are reversed biased and others aren't?


texts:
I made the quintessential newbie mistake: I removed 2 capacitors (CF07/CF08) without noting down the original lead position.

The interesting part is that the schematic (attached) seems to convey that one of them (CF07) should be a bipolar, but the actual capacitors put in place were both two polarized 100uF/10V. Usually I can relay on the schematic to tell me the polarity...but not in this case. Even for CF08, it's hard for me to dare to guess what should be the right direction.

How should I put the caps in place so that they don't explode in my face...? Is there an essential clue in the schematic, or an easy way to tell with a multimeter?


texts:
I'll soon need to test and work with SMD components, but these components are very small, about 2.5 mm x 2.5 mm (DFN package for example).

I had a simple question that I can't answer despite my searches. Do bases for placing SMD components on exist?

What I mean by that, is a component (SMD or Through-Hole) easier to solder on a PCB where I could place and remove a SMD component.

If yes, what is the name of such a component?


texts: USB/Ethernet to a (real) bell based on a signal

texts:
I'm a total beginner in hardware, but I'd like to build a piece of material that would make a real bell ring for a specific duration, or eventually instead of a bell, a light that would switch on based on a specific duration.

The start and duration would be triggered remotely via USB or Ethernet, coded in a Java language (part I'm most experienced with).

I thought about using an Arduino, but since I don't know anything in the hardware area, I'm asking you for your advice on how and what do buy for making this the cheaper way.

Also, it would be great if this device would be sell alimented, I'm most thinking about using an USB then, am I right?

Thank you very much for your help :)


texts: How can I convert data from a sensor register to a float value?

texts:
Can anyone please help me understand how I can convert data from a sensor register to a float value?
Say I am reading the sensor register as following:
R = readRegister(RRegister);

Where readRegister returns uint16_t type data.
Now my question is how should I convert this R to get a value for example 150.134.
Thanks!
Edit 1:
The register I am trying to read is 14h on page 34.
Link of the user guide: [https://pdfserv.maximintegrated.com/en/an/user-guide-6597-max1726x-m5-ez-rev3-p4.pdf][1]


texts: What's is yx8018b and what is it symbol?

texts:
I am trying to fix some solar lamps, that contain pretty much only a handful of electrical components:

A switch
a solar panel
a 1.2 V AAA batery
an LED
a resistor (inside its "home" it measures ca 45 mOhm, it's labeled in Red-brown-violet-Silver [210 MOhm?!])

and then a little black 4-legged thingy labeled

yx8018b av7n1

While I could find replacement parts under the part number "yx8018", I have no idea what the item is called and how to note it down in the accompanying sketch - an if there is a difference between XY8018 and YX8018B.


texts: Using an Induction Heater to melt multiple types of metal

texts:
Right, here's some context. I have a large amount of metal shavings from a dozen different sources, and they are very light and sharp. Some of them aren't, but most of them are. I need to dispose of them without ruining the day of an unlucky employee at a recycling plant. So I intend to melt them into easily organized and transportable ingots.

The only problem is, I also want to learn how to make an induction heater, and all of those metal shavings sound like perfect test subject for this project.

Now, when it comes to making an induction heater, my research has informed me that I need a Tank Capacitor hooked up to an oscillating power supply. The Tank Capacitor part sounds simple enough, I have serviceable capacitors for days, and I have copper pipe from a plumbing project that went nowhere, for the work coil.

The project got complicated when the concept of resonance got introduced. A quick wiki-crawl and an examination of several similar projects revealed that a Tank Capacitor has a specific resonance frequency, where the energy gain (Transfer? Whatever.) is at it's most efficient. The equation can be found with a quick google. However, the inductance, one of the variables used to determine the resonance frequency, changes based on the contents of the work coil. I have been led to believe that it also changes based on how hot the work piece is.

So I have to ask, how do I determine the resonant frequency while the work coil is functioning? Can I just attach a wire to the Tank Capacitor to determine the frequency that its oscillating at, and get the resonant frequency from that?


texts: Why do i get three different methods to calculate the same current ,but get three different current values?

texts:
I want to find the current \$I_R\$,and i used three methods,and i got three different
\$I_R\$ values,i hope someone can tell me where am i wrong!

simulate this circuit – Schematic created using CircuitLab

method 1 & 2  : There are  two circuits  as below,the main difference between them is the direction of \$I_2\$,which are opposite!

Left hand circuit :

\$I_R=I_1=3\frac{(2+3)}{(2+3)+(1+R_L)}=3\frac{5}{6+R_L}=\frac{15}{6+R_L}\$

Right hand circuit :

\$I_R=I_1=3+I_2=3+1\frac{3}{3+(2+1+R_L)}=3+\frac{3}{6+R_L}=\frac{21+3R_L}{6+R_L}\$

simulate this circuit

method 3:superposition

\$I_R=I_{R1}+I_{R2}+I_{R3}=0+[3\frac{(2+3)}{(2+3)+(1+R_L)}]+[1\frac{3}{3+(2+1+R_L)}]=\frac{18}{6+R_L}\$

simulate this circuit

If we use the maximum power Maximum Power Transfer Theorem,we can know \$R_L=6Ω\$.However,now i have a big problem,that is,we can see that when i  replace \$R_L\$ with \$6Ω\$ in the current from method 1 to method 2,we can find that we have three different \$I_R\$ values!!

I believe that  \$I_R\$ value by using method 3 is correct,but i don't know where am i wrong in my method 1 and method 2,can anyone tell me the mistake i made?


texts:
I've hit a bit of a rut in a question on my homework for my computer architecture class (MIPS architecture):

  what are digital logic devices that can implement 1 bit and 32 bit volatile memory, and what are microarchitecture devices that can implement 1 bit and 32 bit volatile memory?

As I understand it a capacitor and a flip-flop can both hold 1 bit, but I'm not sure about the 32 bit answers.


texts: How do we name the "spring-mounted spikes" component on MacBook Pro motherboards?

texts:
How to we name these components that we see on the motherboards of the MacBook Pro (either silvered or gold) when the bottom cover lid is removed, and that seem mounted on springs?

Ancillary, does someone know if their purpose to detect the opening of the cover lid, or to ensure some contact with the mass?
(N.B. The MacBook is still working when the lid has been removed.)


texts:
I'm looking at the following circuit:

simulate this circuit – Schematic created using CircuitLab

It consists of an oscillation whose frequency depends on the tank circuit (C1, L1 and L2). When the voltage of the tank circuit reaches 0v the mosfet that was conducting stops conducting and the one that wasn't starts conducting. This process is repeated continuously at the resonance frequency. What I don't understand is how does the voltage at node A or at node B get to 0v?

For comparison, take this circuit:

simulate this circuit

In this case there is AC through the circuit however the voltage across the capacitor is only 0 at time=0s. Afterwards, it starts increasing, but never decreasing, until it reaches the supply voltage where it would stop oscillating.

In the first circuit the continuous change of mosfets conductance results in a steady oscillation instead of it eventually dying as is the case for the second circuit. Still, I'm unable to see how nodes A/B (from the first circuit) get to 0v. I would expect that the mosfet that firsts starts conducting would charge up the capacitor to the supply voltage which would result in killing the oscillation, that however isn't the case.

Thanks


texts:
I have a Verilog test bench that monitors a 64-bit bus and should randomly schedule a flipped bit (packet corruption) to happen every 1-in-X packets. I was surprised to find it not injecting any corruption, and seemingly this is due to patterns in $random ?

Verilog module, placed inline with bus:

module test_cable  #(
    parameter EMPTY_BITS = 3,
    parameter DATA_BITS = 64
) (
input wire         clk,

input wire [DATA_BITS-1:0]   eth_c2cable_data,
input wire                   eth_c2cable_valid,
input wire                   eth_c2cable_sop,
input wire [EMPTY_BITS-1:0]  eth_c2cable_empty,
input wire                   eth_c2cable_eop,
input wire                   eth_c2cable_error,
output wire                  eth_c2cable_ready,

output wire [DATA_BITS-1:0]  eth_cable2s_data,
output wire                  eth_cable2s_valid,
output wire                  eth_cable2s_sop,
output wire [EMPTY_BITS-1:0] eth_cable2s_empty,
output wire                  eth_cable2s_eop,
output wire                  eth_cable2s_error,
input wire                   eth_cable2s_ready
);

// Corruption control task
// 2'b00  clean
// 2'b01  corrupt 1 pkt in 2^6
// 2'b10  corrupt 1 pkt in 2^7
// 2'b11  corrupt 1 pkt in 2^8
reg [1:0]  ready_control = 2'b00;
reg [31:0] random_next = 0;

task setCorruptControl;
    input [1:0] bitf;
    begin
        ready_control <= bitf;
    end
endtask

// ready bit control
reg [7:0] corrupt_at_cycle = 0;
wire [31:0] random_mask = (1'b1 << (6+ready_control))-1;
always @(posedge clk) begin
    random_next   <= $random;

    if ((eth_c2cable_sop && eth_c2cable_valid) && ready_control > 0 && (random_next & random_mask) == 32'b0) begin
        // corrupt this packet at some point. we don't know how big packet is, so somewhere in first 16 cycles
        // if the packet stops before we corrupt, we'll hit the next one
        corrupt_at_cycle <= random_next[24 +: 4];
        $display("Scheduling corruption %t for +%d cycles %08x", $time, random_next[24 +: 4], random_next);

    end else if (corrupt_at_cycle > 0 && eth_c2cable_valid) begin
        corrupt_at_cycle <= corrupt_at_cycle - 1'b1;
    end

    if (eth_c2cable_corruption != 0) begin
        $display("Corrupting wire packet with noise %016x", eth_c2cable_corruption);
    end
end

// corrupt by flipping single bit in this cycle
wire [63:0] eth_c2cable_corruption = corrupt_at_cycle == 1 ? { 1'b1 << random_next[24 +: 5] } : 64'b0;

assign eth_cable2s_data   = eth_c2cable_data ^ eth_c2cable_corruption;
assign eth_cable2s_valid  = eth_c2cable_valid;
assign eth_cable2s_sop    = eth_c2cable_sop;
assign eth_cable2s_eop    = eth_c2cable_eop;
assign eth_cable2s_empty  = eth_c2cable_empty;
assign eth_cable2s_error  = eth_c2cable_error;
assign eth_c2cable_ready  = eth_cable2s_ready;

endmodule

Looking at the simulation output corruption is always scheduled to occur in zero cycles, so never happens:

...
Scheduling corruption            882531000 for + 0 cycles 40002780
Scheduling corruption            887190000 for + 0 cycles 002edf00
Scheduling corruption            894192000 for + 0 cycles 4049c380
Scheduling corruption            907395000 for + 0 cycles c0270a80
Scheduling corruption            948746000 for + 0 cycles 4010dd80
Scheduling corruption            959389000 for + 0 cycles 40155b80
Scheduling corruption            964957000 for + 0 cycles c0357a80
...
                                                           ^     ^

This seems to be caused by bits random_next[24 +: 4] and random_next[0 +: 6] being zero coincidently. I arbitrarily chose the bits from 24 hoping they would have no correlation with the low bits. Is this a weakness with the Verilog pseudo-random number algorithm, or a problem with the Icarus Verilog simulator?

After much bug-hunting, I modified occurrences of random_next[24 +: 4] to random_next[28 +: 4] and the test bench works.


texts: Connecting unused MIPI data lane in schematics and PCB layout

texts:
I am using a MIPI to parallel bridge in one of my designs. The bridge takes in inputs from a MIPI camera and sends the parallel data to a processor. I am using only 2 data lanes (of the 4 data lanes) available in MIPI bridge input.

Can you please let me know how to connect the unused (2) data lanes from a PCB design  perspective (eg: leaving them unconnected or connecting them to ground) and its purpose?


texts:
I have a circuit which does something not important, but it results in an output being normally low, and then on activation climbs to a little below Vcc. At the moment, it appears my Vcc is 1.8 V and the signal gets up to between 1.2 V and 1.4 V. I want to use this signal to control the gate of an n-channel MOSFET which is grounded on the source and has the drain tied to Vcc through a large resistive load.

The problem is the threshold voltage of the standard MOSFETs I have appears to be too high, and I have to raise Vcc to about 2.2 V in order to get the circuit to trigger the MOSFET correctly. Are there better MOSFETs for this situation or some other design idea that would work well and solve my problem?

BTW, the switching speed is not really a consideration... we're talking 1-200 Hz for frequency.

Application Note, see page 3. I was hoping I could just use their circuit exactly and just mess with the tuning component, but it doesn't seem to work at 1.8 V.


texts: Why does inductor exhibits not symmetrical current behavior?

texts:
I am modelling a PWM switching whose model is shown here below, where the Pulse generator represents my previous PWM stage.

So far, I am experiencing some weird behaviour in the inductor, I see how it does not exhibits a symmetrical behaviour in its current, as in show below when showing the input to the MOSFET and the output after the filter

I wonder why does this happen, is it owed to how it was modelled? Any ideas?

Thanks in advance,

Regards!

Focusing in the inductor current ,I_L,  ** it is shown that there is not symmetry in the current in the Y axe (A) coloured in red**


texts: A line of code is not being executed in STM32 Bluepill while being debugged with BMP in VSCODE PlatformIO

texts:
My Environment:
1- Mac OS
2- STM32 Bluepill flashed with Blackmagic Prob firmware and acts as a Black magic probe
3- Stm32 Bluepill as a development board
4- CMSIS firmware
5- Using Vscode with PlatformIO
My Problem:
I am trying to program my STM32 blue pill and debugging it using a Blackmagic probe (a blue pill with BMP firmware)
I wrote the following code and when debugging it using BMP it starts getting executed but when reaching the delay1() function line of code, control just passes it and doesn't execute it therefore the LED connected to the pin PB11 is always ON but dimmed because it gets switched ON and Off so fast and the delay function is not executed!
My question is:
What is going on? Why would control just jump and not execute a line of code?

/**
 * ? LED BLINKIND SKETCH, PINOUT FOR STM32F103XX
 * ! Green LED -> PB11
 * * Blue LED  -> PB10
 * * Red LED   -> PB1
 * * Pot.      -> PA0
 * * Push Btn. -> PB9
*/

//? ========= INCLUEDS =+=========
#include "STM32F1xx.h"

//? ========= PROTOTYPES ===========
void portsInit(void);
void delay1(void);

int main(void)
{
    portsInit();

    while(1)
    {
        //GPIOB->ODR ^= GPIO_ODR_ODR11_Msk;
        GPIOB->BSRR = GPIO_BSRR_BS11;
        delay1();
        GPIOB->BSRR = GPIO_BSRR_BR11;
        delay1();
    }
}

void portsInit(void)
{
    //* Enable clock to port "A" and "B" (Default SysCLK = 8Mhz ext. OSC):
    RCC->APB2ENR |= ((1<<2) | (1<<3));

    //* Set Pin Modes and Pin Configuration. (Reset Value = 0x4444 4444)
    //! Setting Mode for Pin PB11 MODE[1:0], "Bit1" of the MODE register = 1 and "Bit0" = 1
    GPIOB->CRH |= GPIO_CRH_MODE11_Msk;           // Set PB11 MODE as Output @ 50Mhz (max).
    //! Setting Configuration for Pin PB11 CNF[1:0]
    GPIOB->CRH &= ~(GPIO_CRH_CNF11_Msk);
    /*
        * Final GPIOB->CRH register must equal 0b 0011 0100 0100 0100 or 0x3444,
        * to set pb11 pin as an Output MODE @ 50Mhz configured as General purpose
        * output push-pull configuration.
    */
}// End portsInit() Function.

void delay1(void)
{
    for(uint32_t i = 0; i < 10000000; i++)
    {
        //! LOOP DOING NOTHING WASTING TIME (PSUDO-DELAY)
    }
}

/**     ============= Registers Can be used as well such as: ==================

    //RCC->APB2ENR |= RCC_APB2ENR_IOPAEN;       // Enable PortA Clock
    //RCC->APB2ENR |= RCC_APB2ENR_IOPBEN;       // Enable PortB Clock
    Set pin "PB11" as output push-pull (Green LED)
    GPIOB->CRH |= ((1<<12) | (1<<13));        //Set Pin to Output 50Mhz max speed
    GPIOB->CRH &= ~((1<<14) | (1<<15));       //Configure Pin as Push-Pull

*/

This is my platformIO.ini:
[env:bluepill_f103c8]
platform = ststm32
board = bluepill_f103c8
framework = cmsis
board_build.mcu = stm32f103c8t6                 ; change microcontroller (override)
board_build.f_cpu = 8000000L                    ; change MCU frequency   (override)
upload_protocol = blackmagic                    ; SWD interface
;upload_protocol = blackmagic-jtag               ; JTAG interface
debug_tool = blackmagic
debug_port = /dev/tty.usbmodem7BBB54AD1
upload_port = /dev/tty.usbmodem7BBB54AD1        ; There are 2 Ports, UART and SWD, Check ports in terminal% ls /dev/tty.*

PS. I am using an extension for commenting!


texts: Ethernet RJ45 interfacing with microcontroller

texts:
I am working on a project, (still in the nascent stage) where I have to implement a serial communication interface and an Ethernet interface. I tried to find out as much as I can and got the following information:

For the serial interface I can implement using (DB9/DB25 via max232 line driver)
For RJ45 interface I am in doubt which method is right. Either:

RJ45 => Ethernet Controller IC => Microcontroller(with SPI)
would this method interfere with the serial communication port as SPI would require rxd and txd pins of micro-controller which are used to connect with pins of line driver (totally confused)
RJ45 => Micro-controller( I doubt it)

Kindly advise, please forgive my ignorance I am quite new to networking arena.


texts: LDO requirement for battery powered micro-controllers

texts:
What are the selection parameter for battery powered ultra low powered application?
(Battery capacity of 3700mAh, 3.7V 18650 Li-ion)

I'm designing an application with MSP430/Atmega328 + RF micro-controller (LoRa/Sigfox/BT-LE)

Here Atmega can run on voltage range above 3.3v but RF micro-controller needs voltage from 2.2 to 3.3 Volt, which makes it difficult if entire device is powered by 3.7 V Li-ion battery. Fully charged battery initially has 4.2 - 4.5 V.
Hence its needed to have a LDO before RF micro-controller (150 mA).

This also means LDO will always be in circuit and will dissipate power which will affect battery life. I want to achieve at least few month to years of battery life.

I want to understand the selection parameter that are important for choosing right LDO for this application.
Quiescent Current, Drop-Out voltage.

Any other thought on this application is also advisable.

(Please do suggest changes in question if looks inappropriate or incorrect question)

EDIT - removed less important part of question (using Boost) as I figured out from Li-XX batteries discharge graph, its not needed.

UPDATE - I am targeting for two types of applications:
1) RF Remote Control and

2) Sensor Node

UPDATE: I found this article which theoretically clears many aspects
https://www.analog.com/en/analog-dialogue/articles/applying-low-dropout-regulators.html


texts:
I opened and took out some components of an electric source of a desktop computer that doesn't work anymore (the source not the computer, I bought another source). One of them is a fan DC 12V: HA1225M12S-Z.
When I supply 12V to the welded terminals of the other side of the PCB, where it is plugged, the fan works normally.
My doubt is the electrical resistance of the fan. When I measure it with the \$\Omega\$ function of my multimeter, I get \$20k\Omega\$ what doesn't make sense, because it is written in the fan the current of \$0.45A\$.
Probably the measure is wrong, but on the other hand the multimeter seems to give good values for other resistances.
The function of measuring continuous current is not working, so I can not check the resistance by applying a voltage and checking the current with the fan locked.
I could not find the specification of the resistance of this fan in the web. Am I right to suppose that it must be \$26.7 \Omega \left(\frac{12}{0.45}\right)\$?


texts:
I am just wondering what voltage to use in this situation when calculating the power consumption of a circuit. (P=VI)

I have a 24V DC power supply with 2 x 3V DC motors in the circuit. I have transformed to voltage to suit the motors and have an Ammeter recording the current.

Would it be correct to use the 24V (supply) in the overall circuit power calculation or do you use 3V as that is what the motors are running at?

Thanks


texts: Microe MCP25625 Click Extra components questions?

texts:
I'm trying to implement MCP25625 CAN controller and tranceiver in my design. I checked the dev board of Microe MCP25625 Click and especially in the  the lines CANH and CANL like it is showen in the picture below

Question 1 : there are 2 x 60 Ohm resistors which I guess it is the CAN bus termination ! But if I am plugging this to an OBD for example! there is no need for 120Ohm termination resistor ?
Question 2 : Is 4.7nF between the 2 resistors mondatory here! I usually put 120 Ohm and nothing else ?

Question 3 : What's the purpose of the 47pF capacitor on CANH ? in the MCP25625 datasheet they don't talk about it ?

Full schematic link

I would appreciate your inputs and maybe some links to help me understand the role of these components.


texts: Is earth of a 3-prong AC/DC adapter is connected to the GND of DC output?

texts:
Below is an illustration of a 3-prong AC/DC adapter(such as a laptop adapter):

Here I marked the primary earth ground as 'a'; and GND of the secondary(DC) as 'b'.

My question is are these grounds connected to each other in real??
Can I just check it with a multimeter continuity test?


texts: Measure voltage difference between ground and DC floating power supply lines

texts:
110/220V AC to 12V DC switching mode power supply
(metal enclosed, input is 220V with separate L,N and ground.)

Measured voltage difference with a multimeter between V- and V+ 12V
DC as expected
Measured voltage difference between ground and V- or ground and V+
reads practically 0V DC

According to this text about floating power supplies:

  For floating DC power supplies, the voltage potential appears from
  the positive output terminal to the negative output terminal. There is
  no voltage potential (at least, none with any power behind it) from
  either the positive terminal to earth ground or from the negative
  output terminal to earth ground.

So that is in accordance with my measurement, but how can this be?
If there is a voltage different between point A and B in any electrical network, how can the voltage C-A and C-B both be zero?
The only explanation I can think of is a measuring error (multimeter ties the measured line to the ground?), but if so, the quoted text above is wrong?


texts:
My ongoing (beginner) case-modding efforts have led me to desiring a spinning globe within my computer case. I would like to use a low-RPM motor (something between 4 and 20 rpm) for that and connect it to the PSU to power it.

I have an IT background, but absolutely no clue about electrical engineering and the utmost respect for all of the magic happening there. Therefore, I've searched a lot about the topic, but failed to find definite info, thus I turned here.

I haven't yet bought a motor because I wasn't sure which one would be appropriate, but I think I'd need a motor like this one:

My PSU is an EVGA SuperNova 80+ Gold G2 550W and has plenty of connection options.

My guess was that I could connect that motor to a 12V line, like the ones used for powering fans or components. I'm highly uncomfortable with trying though, so I'd really like to have an expert opinion...

if it is safe at all (I'd like my computer to live long and
prosper) ?
which motor would be best (like the one depicted above?) ?
which internal slot cable to use (12V processor, molex,
fan, ...) ?
how to connect which cable to which slot ?

Can anybody please help me?


texts:
I have an external hard drive that I travel with to back up photos. It has a large (and quite heavy) AC/DC adapter that outputs 12V and 2A DC.

I'd like to be able to leave that home and carry a small USB adapter that will do the same thing.

So 100-240V input / 12V 2A output

As a non-electrical engineering type I have no clue as to if this even a possibility? Can someone point me in the right direction?


texts: 433Mhz Receiver Low Range Only on Raspberry Pi

texts:
I have an Arduino mini pro with a 433mhz receiver attached. I connected this to my computer via a usb to serial cable. I've tried it on two laptops ans it works fine with it (>15 metres), but when connecting it to the Raspberry pi the range is REALLY bad (<1 metre).

I measured the voltage at the 433mhz receiver and it was slightly lower when it was connected to the raspberry pi. I tried to rule this add by adding a voltage booster circuit but it made it worst if anything.

laptop = 4.88v
raspberry pi = 4.3v
raspberry pi using booster circuit = 4.98v

I've not tried an external power supply yet.

Any thoughts on what might be causing the problem?

Thank you in advance!


texts: Problems with doping semiconductor materials in 7nm technology

texts:
As you know, semiconductor technology is going to reach 7nm lithographic precision soon. Which means that the smallest segment length on a semiconductor die can be as short as 7nm. After making some calculations, I wondered how can someone dope such a small silicon block uniformly.

Density of silicon is \$2.328 \;\text{g}/\text{cm}^3\$.
Number of atoms in silicon is \$2.144217404 \times 10^{22} \;\text{atoms}/\text{g}\$.

Then we have number of atoms in unit volume as
\$(2.328 \;\text{g}/\text{cm}^3) * (2.144217404 \times 10^{22} \;\text{atoms}/\text{g}) ≈ 5 \times 10^{22} \;\text{atoms}/\text{cm}^3\$.

I read some papers online and deduced that a typical doping density is
\$10^{18} \;\text{doping-atoms}/\text{cm}^3\$.
Which means that, the doping ratio is about \$50000\$ silicon atoms per each doping material atom.

Now, consider a \$7nm \times 7nm \times 7nm\$ cubic silicon block and we wish to dope it with atoms of some other material. Van Der Vaals radius of silicon atom is \$219pm\$ (found this on Google). After doing some elementary geometry calculation, we can find that \$4082\$ atoms can fit in this block.

We need
\$(4082 \;\text{silicon-atoms}) / (50000 \dfrac{\;\text{silicon-atoms}}{\text{doping-atoms}}) = 0.08164 \;\text{doping-atoms}\$
to dope this tiny 7nm x 7nm x 7nm cubic silicon block, which is less than 1. Which means a tiny block like this have a 8% change of receiving a single atom from the doping material. Which means there is a 92% change that the tiny block will remain pure silicon!

Seriously, what?!

I don't understand this and I have some questions on this.

What happens if a supposedly P-type or N-type substrate (e.g.; emitter of a BJT or channel of a MOSFET) remains purely silicon?
What happens if the block was lucky and it received a single atom of a doping material. Does it matter the location of that atom? What if the atom stays in the farthest corner of of the block?
What happens if the block was super luck and it received more than 1 doping atoms?

In a chip which will contain more than 1 thousand transistors, occurrence of these kind of situations are statistically inevitable. How do they dope very small semiconductor materials? How do they overcome problems like this?


texts: Back EMF and opposing current of a super conductor?

texts:
A 5 meter long super conductor carries 100 Amps, and it passes through a 1 Tesla magnetic field at 0.010 seconds, Is EMF = - (BL) / (t)?

And since the resistance of the super conducting wire is zero, shouldn't EMF = 0 based on ohms law?

Now, lets take another wire with R = 0.001 ohms, and the the induced EMF was 1V for example, the current is V/R = 1000 Amps?!

This is confusing because the magnetic resistance(Lenz law) is massive!


texts: How to build stuff with random components

texts:
I have a LOT of junk, with all of these broken electronics and random components (transistors, resistors IC's, you name it)

It always seems like when I want to build something, I need a specific component and I need to go to radio shack and waste some more and more money component at a time.

How can I salvage these components and make cool things out of them without buying a fortune worth of stuff just to get started on something?


texts: Eliminating buzz or high pitch noise from PWM LED Driver?

texts:
I am tinkering with Adafruit's Charlieplex PWM LED Driver module. And I notice audible buzz when I lit my LED brightness to the maximum. This is noted in their documentation:

  You might notice some buzzing or ringing sounds from the display when
  all pixels are lit, this is normal as the Charlieplex driver quickly
  switches LEDs on and off.

Now, I would like to know if there are improvements that I can make to the circuit to completely eliminate this noise/buzz/hum.

I won't provide the datasheet or schematic here. I think all dimming LEDs have this issue, and I am looking for a guideline or good practises.


texts: Why didn't the IGBT's output voltage change?

texts:
I have a lab experiment and we are trying to make IGBTs switch.
Here is our experiment:

In first situation, our values like that:

10kHz, 10V pulse
Vcc = 15V
Frequency=10k

And with this setup, I can observe 14V output voltage.
In second situation, we only change the pulse's voltage to 15V and the other values same. However, I observed the same output voltage as 14V.
What's the explanation of that? Why did the output voltage stay the same?
By the way: I used Proteus to simulate this circuit.


texts: How can master connect to a slave at a wrong I2C address?

texts:
I connected an IO expander (PCA6416A) to Arduino using I2C bus. I used I2C Scanner script to find the address. I tried clock speeds from 30 to 100 kHz and used 2k and 10k resistors on bus lines. Whaterver I do the script always detects expander IC at address 0x40 while according to datasheet the expander IC is either 0x80 or 0x82 ( actually in my board it must be 0x80). Interestingly I can read IC registers without error but with some noise.
So my questions is why I2C master consistently detects slave at a wrong address?


texts: I have a pet turtle that keeps flipping over in her aquarium.  As a turtle can die if they are upside down too long, I am thinking of creating a simple, self contained position sensor to her back to alert me when she does it.  It would need to be about 1 inch square and maybe 1/4 high and waterproof.  I would like it to talk directly to an app, or to an intermediary receiver then to an app.  I have a 3D printer and can fab the device enclosure, just looking for help on the electronics/mechanics.


texts:
I don't understand why I am getting this behavior from my MOSFET circuit. Either because I'm not using LTSpice correctly, or I'm not understanding MOSFETs. I set up the voltage to the gate to be a ramp from 0 to 30V over 100 ms so I could capture the moment the transistor turned on but the simulation is suggesting the transistor output voltage is linearly following the gate voltage. I thought once the transistor turned on it would be equivalent to closing a switch.

V(n007) is at R3
V(n004) is input to M1
V(n005) is the output of V2


texts: How to use charging adapter to charge Lipo battery through a female USB C receptacle?

texts:
I have successfully created a solar operated (7.4 V 20W PV panel) battery charger to be able to charge my 3.7 V 1 cell lithium battery practically for free! I have attached my schematic below for whoever is interested. I was just looking to integrate a separate power source from the wall outlet to account for days of low solar exposure.
I was looking to use a USB C receptacle (MOLEX 1054500101) to transfer this current from the wall outlet in accordance to the BC-1.2 protocol, I just was not sure as to how or if I required some other supplementary circuitry for pins other than the VBus or GND pins found below
I understand that the D+ and D- pins are essential for data transfer, and in the case of the usb type a female receptacle, it would dictate the amount of current allowed to be pulled by a smart device to charge its battery. Elsewhere, forums mentioned that the CC1 and CC2 pins would require controllers or resistors for DFP UFP configurations which I am not sure are necessary just to supply my BQ24650 chip to charge my battery...
Any insight on this would be really helpful
Thank you


texts: SDC Constraints for digitally noise filtered CLOCK and DATA inputs

texts:
I need help if my SDC constraints are correct for a digitally noise filtered CLOCK and DATA inputs. I'm not sure if CLK3 grouping and create_clk CLK2 are correct.
I would like to know on how to make a constraints of the following.

Constraints for CLK3 (create/generated clock).
Constraints for Input Delay of DATAIN.
Constraints for Output Delay of DATAOUT with respect to CLK2, to guarantee the minimum Input Delay feeding the Master device which will be captured by CLK2 rising edge to insure enough hold time.

Note: The reason for using CLK3 as clock input of FF10 is to minimize power consumption because other than FF10, there are hundreds or even more than a thousand FF's after the filter circuit. CLK2 or CLK3 are not continuous, it will run only as needed and its frequency is much slower than the continuous CLK1 coming from the external oscillator.
create_clock -period 20 -name CLK1 -waveform {0 10} [get_ports CLK1]
create_clock -period 1000 -name CLK2 -waveform {0 500} [get_ports CLK2]
create_generated_clock -name CLK3 -combinational -source [get_pins FF4/Q ]

set_clock_groups -asynchronous -group [get_clocks {CLK1}] -group [get_clocks {CLK2 CLK3}]

# -min 80 due to CLK2 filtering
set_output_delay -clock [get_clocks CLK2] -min 80 [get_ports DATAOUT]
set_output_delay -clock [get_clocks CLK2] -max 90 [get_ports DATAOUT]

The expected timing should look like below.

Any help would be appreciated.
Thank you.


texts: Trying to identify an IC; don't recognize the logo. Top markings 4307 and RR623

texts:
The only markings on this chip (other than the logo, which I don't recognize) are: 4307 and RR623.  This chip is on an audio circuit board, in the sub-woofer of a TV sound system.

I did a search in Google and searched the numbers in DigiKey site.  No luck identifying it.

Second image posted.  Speaker lugs to left of Q1; 470uF electrolytic to the right.  Larger IC below is a linear amplifier.


texts:
What is the cheapest ARM processor with an MMU so I don't have to use uCLinux?
Bonus for non-bga and integrated RAM/Flash


texts:
In my design, I make use of the ATLPLL Library/IP which is to convert the clock frequency accordingly for my design. I am Using De0-Nano board for my project which has cyclone IV FPGA.
The ATLPLL library works on the development-board.
I don't know to use it in the ModelSim environment.

Things I already did
-The Verilog files that are created in the project for the PLL doesn't seem to have any effect, when I add it to the Modelsim and compile.
-Changed the order of the compilation in the Modelsim, still no positive response.

If you need any further details, please ask.


texts: How to calculate output impedance in this circuit?

texts: 0.3k where did come from?? How to calculate output impedance in this circuit I don't understand this


texts: Is it voltage or power of the signal amplified when the opamp amplification is given in dB unit?

texts:
Today, one of my colleague said that he entered a preliminary examination in a company after his job application. One of the questions is exactly "Design a non-inverting amplifier with 20dB gain.". The goal of the question is to find the resistor values \$R_1\$ and \$R_2\$.

simulate this circuit – Schematic created using CircuitLab

If we take this 20dB as "power amplification", then

$$ 20dB = 10 log_{10}\dfrac{P_o}{P_i} \implies \dfrac{P_o}{P_i} = 100 = \dfrac{V_o^2}{V_i^2} \implies \dfrac{V_o}{V_i} = 10 \implies \dfrac{R_1}{R_2} = 9. $$

If we understand it as "voltage amplification", then

$$ 20dB = 10 log_{10}\dfrac{V_o}{V_i} \implies \dfrac{V_o}{V_i} = 100 \implies \dfrac{R_1}{R_2} = 99. $$

Which one is the correct approach?


texts: Advice for High Side Switch (High Current, Low Voltage)

texts:
I'm building a small LED driver microcontroller board and I'm looking for any advice y'all have on switching the power to it up to 9A (would take 3A, if necessary) at 3V - 5V, in a small package. I've not worked with high-side switches before, so I would love any recommendations or feedback you have.

For reference, this is the size of the board (a couple of chips were added recently, so it has even less space):

Hardware Switch

I'm currently using a (GPTS203211B) push-button switch. For the size, the highest rating I can find is up to 1A at 30V.

Question: If it's rated 30V/1A (30W), could we assume that it would be okay at ~6A at 5V?

Otherwise, I feel like I should pair it with a solid-state high-side switch.

Solid State High-Side Switch

Any recommendations on a good high-side switch circuit or IC for this application? The board is already tight on space, so smaller and fewer additional parts is better. Through-hole would also be okay.

I'm currently looking at this one:
https://www.digikey.com/product-detail/en/NCP45520IMNTWG-L/NCP45520IMNTWG-LOSCT-ND/5801848/?itemSeq=327830435


texts: Does LED thermal need to be isolated from GND in this case?

texts:
I'm designing a small LED device which is powered by a battery.

The case of the device is acting as the GND line between the battery and the LED driver, but it is also acting as the heatsink for the LED.

Between the LED cathode, feedback pin and GND there is a sense resistor. Will I need to electrically (but not thermally) isolate the thermal pad of the LED to the case of the device in my design?

Simplified schematics below:


texts: Calculating rechargeable battery charging rate curve

texts:
I am trying to understand the rate of charge of a rechargeable battery - let's say, a Li-ion one. What I'm interested in, is to understand whether the charge (the "percentage" of the Ampere-hours the battery can hold) in the battery is accumulated homogeneously over time. For example, if 2000 mAh battery takes 2 hours to get charged in a certain charging regime, whether after the first hour, it will act like a 1000 mAh battery.

It seems logic to me that if you keep the battery under constant current during the charging, then the rate of charging will be constant as well, but as the voltage of the battery changes over time - but what about other charging regimes? Is there any way for me to deduce charging rates from curves such as the one brought in Fig. 5 below (from A Designer's Guide to Lithium Battery Charging - DigiKey)?

Figure 5: Li-ion charging profile using constant current method until battery voltage reaches 4.1 V, followed by “top-up” using constant voltage technique. (Courtesy of National Semiconductor.)


texts: Input filter on DC-DC converter when it is the only load on a source?

texts: Many app notes recommend placing an LC filter on the input of a buck converter to stop switching noise travelling back and thereby affecting other parts of the circuitry. But in the scenario where everything in the circuit is powered off the buck converter which is connected to a say a battery, would you still get some benefit in terms of cleanliness on the output of the buck converter by having the input filter?


texts: How to choose Toroid core to improve DC current measurement

texts:
I'm currently working on a project where I'm using a linear Hall-Effect sensor to monitor changes in DC current.  This DC current is modulated at anywhere from 15 to 20 Hz.  The magnitude is around 125 Amps DC with 5 to 10 percent modulation.

I'm not interested in the magnitude of the DC current. Rather, I'm interested in finding changes in the modulation amplitude.

The sensor that I'm using is working well enough for "proof of concept"  but I'd like to get more amplitude out of the sensor.

The obvious solution is to purchase an inexpensive DC clamp-on ammeter and strip it down to only the parts that I need (jaws / clamp assembly & Hall-Effect sensor).  But I was looking at some plastic clamps that I have hanging around and it occurred to me that the circular inside diameter of a plastic clamp would hold nicely onto a largish toroid core.

My idea is to find a suitable toroid core and split it such that I have two half-circles.  These would be glued into the plastic clamp with the rear split having the Hall-Effect sensor in the gap.

I'm completely ignorant about the magnetic characteristics of toroid cores.  Most of the cores that I have seen / worked with are used at various RF frequencies.  I'm assuming those are either Ferrite or Iron Powder.  I've also looked at tape-wound toroid cores in the past.

I'm looking for guidance in choosing a suitable core.  I'll do my initial testing with a substantially-higher frequency (60 Hz) but that's what I have available in my lab.  When I have something that seems to be working, I'll take it on site and try it with the actual system it needs to work with.


texts: How do I set the Oscillator module in a DSPIC33E?

texts:
So ive got a DSPIC33EP128GM604 PIC, and Im trying to set the internal fast RC oscillator as the clock source. Ive read the datasheet and the application note both of which tell me to use the macro:
 _FOSCSEL( OPT1_ON & OPT2_OFF & OPT3_PLL )

However, whenever I set the relevant bits, i get the following error during compile time:

  computed address for section __FOSCSEL extends beyond MEMORY region FOSCSEL

Ive googled this problem, and searched the Microchip forms but oddly i can find no similar problems and solutions. Ive selected the mentioned PIC in the project and have set up all the relevant header files (i used the DSPIC33E template provided by MPLABX).


texts: arduino/raspberry based current and voltage monitoring using Rogowski coil

texts:
I am working on a project to build a current and voltage monitoring device (3 phase) using rogowski coils as sensors. It seems that usually CT are used with raspberry or arduino so I would like to have your opinions:
using Rogowski coils, what kind of ADC/integrator (or integrating ADC) do I need (are there different types)?
Concerning ADC: can I make/program one myself or is it best to buy one?
Thanks in advance!
cheers


texts: What is the canonical form based on sinus of the autoinduced EMF in a coil

texts:
I am stuck with this exercise as I can't really find the expressions I need in order to solve this. Please help me & guide me theoretically, so I can finish this.

Deduce the canonical form based on sinus of the autoinduced EMF in a coil knowing that: L = 3 [mH] ( I think it's called inductance in English or inductivity ) and that the coil is traveled by a current given like this:
i1 = 3√2 sin(314t + pi/3) [A].

So basically what I got out so far is this:

I1 ( complex number ) = 3 [A] and γ1 = pi/3 [rad]

I also found somewhere this formula regarding the EMF: e = -L * (ΔI/Δt) but I have no idea if it's the right one to use and exactly how and why to use it to get my desired result. Any ideas guys?


texts: What is the maximum force that a FSR sensor can detect?

texts:
Force Sensitive Resistor (FSR) is a sensor which lowers its resistance when there is force upon it. If there is no force acting on it, the resistance is ~10MOhms.

In the datasheet of FSR A401 of FlexiForce (here), it is mentioned that "measurement ranges of 0-1 lb and 0-7000 lb are achievable with the A401 sensor by utilizing the recommended circuitry. The force range can be extended by reducing the drive voltage, VT, or the resistance value of the feedback resistor, RF. Conversely, the sensitivity can be increased for measurement of lower forces by increasing VT or RF."

Here is the circuit:

And here is the plot of Volt/Force for 3 ranges:

1- If the force range of sensor is dependent on the interface circuitry, then why standard range is defined to be 111N (0-25 lb) ?

2- What is the trade-off here? Is it the sensitivity? I mean if we are in 25 lb range, we can distinguish between 5 and 10 pounds by 1 and 2 volts. But if we are in 100 lb range, the same force range translates to only 0.2 volts. So if we have 10 bit ADC, the first case is 1024 levels but the second case is 204 levels. Am I right?

3- Is this sensor really capable of withstanding and discerning 2 to 2.6 tons of weight?

4- There is a limit on the current flow this sensor can tolerate. Suppose it is I_lim. What is the best way of getting sure that this current limit is not crossed over? I used a simple series 2k and 5V vcc so current is always below 2.5 mAmps. But this method changes the sensitivity (or doesn't?) Is there a better way?

Thank you very much :)


texts: Which electronic switch to use with 5V as triggering signal and 12 V as actual signal?

texts:
Which electronic switch should I use if I want to control 12 V,1A signal with a 5V Arduino output signal? (12 V is high powered signal so I can't use s boosted 12 V output from a 5 V Arduino signal - Image is below]l.)
Some specs:

The switch should work instantaneously (Edit: 10-20 milliseconds maximum.)
Only triggering ON is needed. If an option is available through which we can only trigger on and later turn it off in any other way, that option is welcome too

I have tried:

MOSFET but I guess it doesn't work for gate voltage 5V if 12 V signal needs to be passed through.
Triac & optocoupler - it turns on alright but it's not turning off in any way I know


texts: IC for converting single phase to three phase

texts:
I want to design a device to control a 0.5 HP to 3.0 HP three phase AC motor with single AC power.

I need to able converting single phase to three phase. Also an three phase ac motor controller should be added. Is there any IC and modules for helping me in this project?


texts: Is there an electronic pre-treatment spray for long life reliability in connectors?

texts:
Is there a good spray or paint-on treatment that I can apply to small electronic connectors before connecting them, that will help them maintain a good connection over long spans of time?

I am building custom lighting systems (indoor & outdoor) that contain connectors to separate different parts of the electronics.  I've had issues with connections becoming unreliable over time (dirty? oxidized? not sure... the pins look fine), causing lights to flicker, and even fail, due to the connection.  I'd like to find a way, short of soldering, to make these connections more reliable.


texts: Vacuum tube emission (anode current, transconductance) percentage that is considered GOOD

texts: Russian vacuum tube datasheets almost always specifies anode current like Ia = 100 mA +/-20mA at some conditions. The same with  transconductance. But western tube datasheets specifies only one central value - for example Ia = 100 mA at some conditions. What is widely accepted tolerance in percentage to consider tube is good?


texts:
I'd like some advice on how I can negotiate a Qualcomm Quick Charger up to a certain voltage. I have a "dumb" appliance which usually uses its own transformer/"wall wart" at 12V 1A. I also have a USB Quick Charge adapter which can supply 12V 2A, so in theory I can create a cable to adapt that USB charger and replace the wall wart. However, the charger won't output 12V unless a charge controller tells it that the device can use the extra voltage. This negotiation is usually performed by a charge controller on a smart phone.

Is there a simple device on the market that can do this? Alternatively, is there a circuit I can put together to accomplish this? Here is a diagram which illustrates the idea. Basically I need to output 12V to a "dumb" device, so an independent charge controller is needed.


texts: Can a linear solenoid be as efficient as a brushed motor with a gearbox?

texts: I've heard that linear solenoids are power-hungry and tend to overheat, especially if the stroke is long. Can a linear solenoid be as power efficient as a motor with a gearbox that converts rotary motion to reciprocating motion?


texts: How do integrated circuit design companies create their datasheets?

texts:
Especially for something like a microprocessor.

I assume the majority of information is "auto-generated" or we'd see a lot more typos and errors.

A laughable scenario keeps popping into my head where a handful of engineers pass around a word document, export it as a PDF and then manually apply bookmarks.

Are these companies big enough that they can afford to have departments that churn out custom software, databases, etc. to assist their design process?

I'm very curious because I'm finding it very hard to keep data/information/specifications uniform throughout the design process.

Maybe this question belongs in a different exchange?


texts: What is the correct way to measure DC power at the output of a boost converter in a Simulink simulation?

texts:
I modeled a DCDC boost converter, and I would like to measure the power at the output of the converter, I do not understand much about simulation times, sampling, and this sort of thing, so I do not know how to properly evaluate the actual output power of that converter, but I think it's not just V * I. Could someone give me some light?

The first method I used was to calculate Irms and Vrms and do the multiplication.

The second method was to get the Vrms to squared and divide by the Output Resistor

The method I used to calculate the average value of the power was to take the instantaneous value (just the multiplication of V and I) and go through the block "Mean" using as fundamental frequency 25kHz which is the switching frequency.

Are any of these methods correct, all wrong, or is there any better way to do this in simulink?


texts: PCB Board drawing high current when little bit of liquid gets into it. How to debug the board?

texts:
I am new to circuit design and debugging them. I have recently helped in building a PCB with certain kind of circuits on it which includes opamp, boost converter, microcontroller and accelerometer. The board is battery operated. It basically goes on a device which is supposed to be water proofed. But by any reason the water can go inside the device.

The circuit is works fine it draws minimal sleep current in micro amps when in sleep mode and set current when its measuring. But when the liquid(approximately a drop of liquid and it would have already dried up "the liquid is mostly sugary") gets into the board "the board still works it even measures" but it starts drawing more current. Hence the battery gets drained faster.

My question is
Can I debug the boards and bring it back to its normal working condition? If so how to debug it?
I have 4-5 boards which are in the same condition will they all have same problem if I debug 1 board?

It would be really helpful if I could get some help from this forum.

Thanks


texts: Magic Eye Tuning Tube Variable Negative Voltage

texts:
I am thinking about several applications of magic eye tuning tubes as display pieces and had a question about their operation. I have attached a sample circuit from a datasheet for an EM84 tube. I know the shadow is controlled by the voltage on pin 1, (the triode control grid), where the shadow shape changes as the voltage goes from 0, to some negative value, usually ~ -20V.

My question is how to build a simple circuit to output a variable voltage of 0 to -20V. Currently I have the tube powered off a power transformer, so I have 6.3 VAC for the heater, rectified 300VAC for the target, and the transformer also has a 28VCT. Other than using something like LM137 after rectifying the center 28VCT outputs, is there an easier way?

Thanks in advance and sorry if my question had any errors, I am by no means an expert in this field.


texts: Understand boost converter's voltage conversion ratio

texts:
Below is a boost converter with its inductor current waveform operating in DCM.
The voltage conversion ratio of the converter is as follows:

M(D1,D2) = V/Vg= 1 + D1/D2

where V and Vg are output and input voltage respectively.

From the formula we see that there are two ways to increase the conversion ratio:

Increase D1.

This makes sense because the longer the D1 the more energy is stored in the inductor in the time period.

Decrease D2.

I couldn't explain it intuitively or physically how it is so. When D2 is decreased, how does it affect output voltage intuitively or physically?

Thank you.


texts:
I was wondering if there is a simple 555 Timer circuit, or even simple transistors circuit, that has a HIGH output for 1sec, 2sec, or more seconds when I trigger the input switch and will remain HIGH till the specific time is done then it will go LOW. Knowing that when I trigger the input switch like 5 times quickly and repeatedly this shouldn't impact/interrupt the output at all, which means when I hit the input switch a multiple times the output will go HIGH for 3 seconds or whatever the time and will turn off once time cycle is done, and will go HIGH again for another 3 seconds if I'm still hitting the switch!

Sample timing diagram for OP to edit:

          _   _   _       _   _             _   _   _   _   _   _
Trig    _| |_| |_| |_____| |_| |___________| |_| |_| |_| |_| |_| |_
          _________       __________        _________   __________
Out     _| 3 s     |_____|   3 s    |______|   3 s   |_|   3 s    |__


texts: How to account for input noise on a zero crossing detector op amp?

texts:
To save potential confusion let me start by saying I just started learning opamp theory about a week ago. I'm currently familiar with inverting, non-inverting, summer, and difference opamps.

My (fairly new) understanding of zero crossing detectors is that when the input signal crosses from positive to negative or vice versa the polarity of output of the opamp will change as well. Essentially it's useful for converting something like a sine wave to a square signal.

If my understanding is correct then what happens if noise is introduced on the input line? I understand better with examples and numbers so let's say I know my noise oscillates over 0v at 100mv peak to peak. How would you account for that?

EDIT: If possible a schematic drawing of a before and after case for handling the noise would be extremely helpful!


texts: How to calculate frequency of this Op Amp square wave oscillator?

texts:
I was trying to come up with the equation to calculate the frequency of this circuit.
R1 and R2 are creating analog ground because I am using bipolar op amp for a single supply operation.

Thank you in advance!


texts: Decoding waveform from RFID 125 khz reader

texts:
I've recently bought a chinese reader for EM4100 and compatible cards: it has an USB to UART converter to get commands from the software and an STM8S10 MCU responsible for the RFID comunication.

I would like to record the waveform and to read the data transmitted from it (for an EM4100 tag, this should be encoded using Manchester encoding).

This is the diagram of the reader:

I don't own an oscilloscope so this is what I did based on a similar work someone did on an italian forum: I've connected a wire to GND and another wire to the joint between the transistor, C19 and R18. Then I've connected these two wires to an USB audio input device (with a capacitor on the MIC in wire) and I'm recording the waveform with audacity.

This is a screenshot of the overall recording (The EM4100 card was near the coil during the period between the two arrows):

This is a zoom in at the first arrow:

This is the wav file of the audio between the arrows:

https://drive.google.com/file/d/1F4_llgKYyv9ev7ozk_84BmQbSsX5BoQA/view

These are the bits that should be transmitted by my EM4100 tag (with data: 0x1E002C4752):

HEADER
1111 1111 1

0001 1        VERSION NUMBER OR
1110 1        CUSTOMER ID (0x1E)

0000 0        DATA (0x2C4752)
0000 0
0010 1
1100 0
0100 1
0111 1
0101 0
0010 1

0101         COLUMN PARITY BIT

STOP BIT
0

I'm not able to see these bits, I can't see the edges of a Manchester encoding in the recorded wave.

Since the software shipped with the reader is really poor my goal is to be able to read the waveform directly and (in the future) to be able to read some unsupported tag by inspecting the wave with an arduino like MCU.

Did I solder the wires to the right points?
Am I using the wrong aproach?

Edit: I soldered one wire to GND and the other one to PIN 13, I got something that's more like a square wave but I still can't figure out the period to decode the Manchester encoding.

Screenshot of the beginning (sorry for my poor drawing skills):

Full WAV file: https://drive.google.com/file/d/1RLqpjuNd4ezlbq2BabBg9FQKhWtj_fYV/view?usp=sharing


texts: High resistance, no current. What's the point of a potential then?

texts:
I am referring to this example:

Why does it matter that the IC has a high resistance? What does this do for/to the IC?
If there is a potential but no current, what is the point of using the IC when in the end no current would run through? Would the device even work?


texts: 18650 battery holder: SMT or THM for 15A?

texts:
While looking for a quality and high current (max 15A) 18650 Lithium battery holder, I've found that Keystone offers:

Surface Mount Style with contacts of stainless steel and "gold flash over nickel plate" finish;

"Gold Flash for outstanding solder performance and low contact resistance" (source: Keystone)

Through Hole Style with contacts of stainless steel and "tin nickel plate" finish;

"Tin over Nickel plate for superior soldering." (source: Keystone)

Here an overview from Keystone website.

I am not sure which one to choose:

The pin of the Through Hole Version are about 1mm diameter, while the SMT version has 6x7mm pads. So I wonder if the Through Hole can carry more then 2-3A. I've read in a forum of somebody getting 20-30A, but this is unverified.
The SMT version could be better for my case but it has gold flash finish contacts, which 18650 batteries usually don't. It is advised not to  mix gold and tin contacts due to the chemical reaction  over time that will deteriorate the electrical connection.

What's your experience or suggestion? Are my worries valid?

The description from Keystone don't help much and there is no mention of Current Rating or other electrical properties in the datasheets.


texts: How to control output resistance with voltage

texts: I want to use an LM555 and change the R1 resistance with voltage gradually (staircase waveform). What circuit can i use to change the resistance by changing the voltage?


texts:
I wonder how you can achieve that a GPIO pin accuratly toggles according to a certain pattern. This pattern is fully variable (no PWM) and is stored in memory.

My conclusion of this is:

The pin has to be set/reset by hardware, not in an ISR
DMA is needed for data transport

What I have in mind:

Upcounting Timer
DMA Channel for updating ARR with pattern data
Compare Channel for toggling pin
Second DMA Channel for updating the compare channel register with same pattern data at the same time

Could that work? Or is there an easy way to do this?

If this works, could I use a second compare and a third DMA channel to toggle another pin invert to the first one?

Facts and requirements:

A 72 Mhz Crystal drives the STM32
Minimum pulse is 10 us
Tolerarable Jitter is less than 100 ns
Duration of longest ISR is greater than 100 ns


texts: Multiples voltage on a optoisolated MCU input problem

texts:
The problem
Handle digital inputs on a MCU, the input could be 5V, 12V, 24V or an open collector.
My solution
My approach is based on jumpers, given the fact that the inputs dont change behavior in time (if the input is 0v or 5v it will be that always and never will change to 12v or 24v or open collector), so I set the jumpers one time in my circuit to work with the desired voltage. This is the most smart way i can think to solve this.
How it works
If the input is 0V and 12V, I set JP2 to 1-2, JP3 to 2-3, JP5 to 1-2 and JP7 to 1-2. If the signal is open collector; I set JP2 to 2-3, JP3 to 1-2, JP4, JP5 and JP6 dont care and JP7 to 2-3.

This seems to me the best way to go, but I don't like the amount of jumpers in my circuit, what do you think? what will be your approach?


texts: When placing a new line it doesn't get assigned a net, how to fix it in Altium?

texts:
I had this working well before, but now, every time i'm placing a new line from a component, it never gets assigned the net.

In the Net field it is always "No Net", which forces me to manually place the name of the net everytime.

How can it be fixed using Altium 18?


texts:
I'm trying to drive a STP16FN06 from a Raspberry Pi GPIO pin but I'm a bit lost.

The schema below represent (I think) how it is currently wired, on the left the RPi pin + ground and on the right a 5V DC supply.

simulate this circuit – Schematic created using CircuitLab

If I remove the MOSFET and plug it directly to the 5V, it light up so this part is ok.

When I set the pin to high, I have 3.3 between it and the ground but nothing shows and from what I understand the MOSFET should be on between 2 and 4V.

I'm not really sure what I've missed but being a bit new to electronics there's probably some beginner mistakes in there.