texts:
I'm trying to charge 3 batteries via 2xRS3s in parallel for charging the 12V batteries.
I got in touch with manufacturer and said that they work well in parallel.
The issue is, after couple times of using,  2 relays which are controlling the supply voltages of each charger, gets stuck in between NO and NC. Tried brand new relays, it did the same. What would cause a relay to get stuck like that? Inrush current of chargers are 7.8A, did bunch of tests about it. Any opinions- suggestions would help. What am I doing wrong?

Coil voltage - Powered with 12V batteries ranges between 11V to 13.9V
Contact voltage - 208VAC
Continuous current draw from load(charger) - 2A
Inrush current (worst case) - 7.8A


texts: Replace Potentiometer With Arduino Controlled Circuit

texts:
Background:
I recently bought a Scr Voltage Regulator (10000w Ac110v 220v 75a) to act as a motor controller for a hobby project (Figure 1). After taking it apart, I found the Voltage Regulator is controlled by a 220k Ohm 2W Potentiometer (Figure 2).

Figure 1: SCR Voltage Regulator

Figure 2: 220 K ohm 2W Potentiometer
Question:
I'd like to replace the mechanical Potentiometer with a component I can control with a microcontroller. I found the ADN2850 However, this seems like it can only support 1 W.

Is there another type of chip on the market I should be looking at?

OR

How would I build a circuit that allows me to use a smaller control current to regulate the speed regulator?


texts: Primary and secondary currents of a transformer driven with clock pulse

texts:
What will be the primary and secondary current waveforms of a transformer whose input is a clock signal?

I have set up a circuit using CircuitLab.

simulate this circuit – Schematic created using CircuitLab

I used Lm to model the magnetizing inductance (i.e.; the inductance seen from the primary side when secondary is open). I don't know the best way of modeling it, so I tried both connecting it in series and parallel. When I omit it, the transformer behaves like ideal and perfectly conducts the pulse applied from primary side to the secondary side.

(Lm is in series with the primary.)

(Lm is parallel with the primary.)

These simulation results partly answers my question, but I also want to know what would happen when the duty cycle (D) varies between 0.1 to 0.9. How it looks like when there is a DC bias because of high duty cycle rates. And why the current waveforms are drawn as triangular wave (with straight lines) in theory. If connecting Lm in series is the correct way of modeling it, why the secondary side current is always at negative in this case.


texts: I am well aware about programming processors and microcontrollers in C. But can C code (not SystemC) be used for logic design for FPGAs? Are there any specific software tools for this purpose?


texts:
I need to add a 1K ohm resistor to a HDMI connector to solve some EDID HDMI issues.

Here is the image of the person who already did that.

My quesion is: Considering that voltage of pins to connect to resistor is 5V and amperage is (perhaps) 50mA; resistor 1k ohm of what wattage should I purchase? 1/4W, 1/2W, ... ?

Thank you.

EDIT:

I don't know why they suggest to shortcut those pins in that article...

If I will use 1000ohm; with 5V voltage => 5mA will flow through resistor? The power will be 0.025W.

If I will use 1/4W resistor, it will not overheat, right?
1/4W is max value of that specific resistor to work with NO overheat?

article


texts: Capturing mains AC waveform with audio recording device

texts:
I'm wondering how practical (read: safe) it would be to use an audio capture device to "record" a mains AC signal for the purposes of monitoring the characteristics of the AC sine wave.
I am thinking something relatively simple like a feeding the live conductor through a resistive voltage divider and straight into the audio input.  While this won't provide any isolation (but see below), I am assuming this will avoid any unwanted smoothing/filtering that could result from using a transformer to provide the isolation.  However there is such a thing as a small 1:1 audio isolation transformer, but I'm not familiar with their behaviour - would they pass a 50/60 Hz sine wave of unknown quality without filtering it in any way?  Obviously if it only passed through the 50/60Hz base frequency I wouldn't be able to see any distortion in the waveform so I imagine I will need something with a large enough bandwidth so as to allow any distortions to be accurately captured.
I would like to use a Raspberry Pi for the audio capture, mostly because it has an Ethernet connection for remotely streaming the waveform captures for display on a PC, but also because it has local storage to keep the captures in the event of a network interruption.  Since it can be powered over the Ethernet connection and this also provides electrical isolation, I figure the solution with the resistive voltage divider isn't so bad because although the Pi itself would not be isolated from the mains, everything else would be.  So long as the Pi is in a proper enclosure with the appropriate warning labels about it being mains referenced it should be fine...right?
My reasons for asking are that I am planning an off-grid set up and would like to experiment with using 3-phase motors as generators, so I would like to be able to continuously monitor the generated AC waveforms partly out of curiosity, and partly to have a way of identifying potential issues.
Being able to treat it as an audio recording also potentially allows me to capture say 24 hours worth of waveforms on a loop so that if anything goes wrong, I can look back and see what the power quality was like leading up to the event (e.g. frequency gradually dropping until it went out of range.)
There are devices you can buy that store waveform captures designed for power quality monitoring, but they are industrial devices and prohibitively expensive for hobbyists, so it would be great if I could accomplish the same thing myself with commodity parts.


texts: I want to design a joule thief circuit with input of 2mV and output 1.5V

texts:
I want to design a joule thief circuit having an input of 2mV and output of 1.5V.
I searched for low input joule thief (JT) and I found that by using ALD110800/ALD110900 (they have zero threshold voltage) I can design one. But the problem is that I cannot find these MOSFETS in my city and I don't have time to order these online. So is there any other MOSFET or transistor that I can use for my JT?
Also can you tell me the design formula's for JT.


texts: Is there a down side to setting the sampling time of a SAR ADC as long as possible?

texts: In configuring the sampling time for the internal ADC of a micro-controller (STM32F446RE) to sample the output of a current sensor connected to a PWM controlled motor, the sampling is triggered at 100kHz and I have a window of between 3 and 225 ADC clock cycles (22.5MHz) over which to hold the sampler open - my assumption is that the longer its open the less noise I'm going to see in the results. Is this correct, or is there a point where other factors come into play that would make a more intermediate sampling duration preferable?


texts: Paralleling two VR - when neither is overloaded

texts:
I have two very simple assembled voltage regulators using AMS 1117-5.  They are a 5 VDC output @ 1 Amp (I have seen some paperwork state 5 VDC @ 0.8 Amp).  The current draw of the Raspberry Pi with attached load is 0.65 Amps.

I need to keep things small and simple so I would like to connect the output of each regulator in parallel.  The voltage is more important than the current draw. I cannot use OR Diodes or anything that would drop the voltage.

Do you think there would be any issues in just hooking them in parallel?


texts: Will this circuit function as an automatic supply changeover upon main supply failure?

texts:
I have drawn up this circuit as a supply system for an automatic changeover from the mains supply to the solar cell - battery supply.

Will the circuit function as intended? What is the correct way to draft this?


texts: Next step when troubleshooting a PS/2 keyboard PCB with good cable

texts:
I received a PS/2 keyboard (TypeMatrix 2020) which was known to be broken, with
some hope that I may be able to fix it. I don't have a lot of experience with
electronics, but I know the very basics. However, I'm unsure what to look for
next.

I have ensured the cable is working, so let's get that out of the way first.

The PCB inside the keyboard, which I copied to the best of my ability, appears
to be designed like

where "IC" in reality refers to a DIP40 controller, but the pins not included
here are either intentionally unconnected or data lines going off to the key
matrix.

I read that old capacitors are a common problem, so – not knowing how to check
for that – I measured the resistance across all capacitors. Only C1, which is of
a different type from the others, gave me any reading at all (a high 10 MOhm ish
number, but steadily decreasing as I kept the probes on it). That feels like too
high a number to matter in practise, but is that so?

C1 is marked 10 uF, 25 V. The other three are apparently ceramic-type, but their markings decode to C2 being 100 nF, while C3 and C4 are 47 pF.

What would be the next step to check?

(Side question, not relevant to main issue: What is the purpose of the coils L1 and L2? I assume they form some kind of filter?)


texts: what's the purpose of this transistor setup (answer: simulate an inductance)

texts:
I encounter the following block in three regions of an Altec Lansing APT3 2.1 speaker system.

simulate this circuit – Schematic created using CircuitLab

Given that VH = 9V D.C., I only understand this as an elaborate voltage divider. What would be the purpose of that construction wrt VD ?

--- Edit ---

Given Olin Lathrop's answer, here's the context in which this circuit is used.

simulate this circuit


texts:
simulate this circuit – Schematic created using CircuitLab

Please help.... I have an input of 7.5V but when it goes out of the circuit the voltage drops in 2.5V but i want 5V of output voltage thats why i borrow 7805 transistor, what is the problem in my circuit. It will be a big help if you help me so please.. thank you..


texts: What are data available and data required in SSI/SPI

texts:
I'm trying to understand SSP/SPI but I'm stuck on the concept of data available and data required. Here's how it explains it in the textbook (Valvano's Introduction to ARM Microcontroller):

The key to proper transmission is to select one edge of the clock to
be used by the transmitter to change the output, and use the other
edge to latch the data in the receiver. In this way data is latched
during the time when it is stable. Data available is the time when the
output data is actually valid, and data required is the time when the
input data must be valid.

Well, if I transmit a data then the FIFO will push those the data bits to the shift register where the clock then pushes the bits out of or into the I/O. When I write data then there is data. If I don't write any data, then there is no data - what does it mean by data available? Or does it imply a control register to skip an element in the FIFO and make the data available or unavailable to read or write?
What is that Gaussian distribution arrow between S8 and S9. Is that some sort of probability that the data can be read properly? Hence the validity of data or some percentage of error?
"...Data required is the time when the input data must be valid..." So data required is a time? Data is being transmitted in Tx and clocked by Clk. What is data required and why is it a time?

<img src="https://i.stack.imgur.com/wWvPV.png" alt="Synchronous serial timing showing the data available
interval overlaps the data required inte" />


texts: Would this design for Li-Ion cell protection+balancing circuit work?

texts:
My team and I are currently trying to design a 2S2P battery pack for use in a CubeSat (student project). The pack is planned to be used with 30-40% depth of discharge for a total of around 5800 charge-discharge cycles. We have chosen to use 4x Panasonic NCR18650B Li-Ion cells. Now we need to design a protection circuit that is also capable of balancing the cells. I have found couple of chips that should do the trick, but I would like to know if this is a good design.
For balancing I have found a simple IC called BQ29209 from Texas Instruments. However it only offers balancing and additional protection circuitry would have to be implemented, such as Overcharge, Overdisharge, Overcurrent and short-circuit protection. For this I have again found an IC called S-8252 from Ablic (Previously known as Seiko), which seems like a pretty reputable manufacturer in battery protection area. Now it seems like these two IC’s together would provide full battery protection together with balancing, but my question is, can they be used together? I am imagining connecting them in way shown in the image below (excuse the crude diagram). Would that be an OK thing to do?

In my opinion they shouldn't interact negatively with each other as the only thing BQ29209 does is activate discharge mosfets when one of the cells goes over the voltage limit, and that shouldn’t mess with S-8252 operation, but maybe I’m not seeing something?
Thank you for your help!


texts: Is it not recommendable to use a spectrum analyzer in its limit frequencies?

texts:
Suppose we have a spectrum analyzer whose range of frequencies goes from \$x \ \mathrm{Hz}\$ to \$y \ \mathrm{Hz}\$. Is there any problem that could arise from measuring signals that are near those frequencies? Any kind of "border effect", or something of that nature.

For instance, Keysight's N9320B states in the datasheet that the frequency range starts at 9 kHz. If I want to measure a sinusoid at 9 kHz, would there by any problem or uncertainty due to the fact that this frequency is at the limit of the SA operating range? (I'm not interested in just that SA, but I just put it here to show what I mean by 'frequency range'.)


texts: First time during my entire engineering career I have been to an emc lab last week. My design has failed to satisfy FCC requirements. The board uses a 25mhz clock and we have failed at 500mhz but I can also see other harmonics being high. It turns out a connector with an unshielded cable is acting as an antenna and failing us however i suspect the problem is deeper.  I can probably shield the cable and pass however this feels like a band aid solution. How do I trace the deeper problem without accessing to a full blown lab. ( every day at the lab cost about 3k). I am specifically looking for troubleshoot advice of where to look and methods of verifying or tracing the problem without a lab but with a low end spectrum analyzer.


texts: What is the purpose of D1 on the gate of the MOSFET? [NCP3065]

texts:
I've built this DC-DC LED Driver, and don't quite understand the purpose of D1. In particular it works with a 1N4007, but I wanted to replace it with a Schottky type for faster switching since the 4148 is much faster than a 1N4007, but the circuit fails to power up properly.

I understand that diodes conduct in one direction, but there is no need to prevent reverse flow of current in this situation. The only thing I can think of is maybe for it to turn off faster in the sense of having a constantly present ~0.7V on the diode to accelerate the turn off?

Or possibly is this diode creating a lower voltage essentially like a bootstrap device since Q1 will be turned OFF when the SWC is open to ground?


texts: Power Supply Output Terminals not isolated

texts:
I have an 20v power adaptor. But I noticed that the output +ve and -ve terminals are not isolated. I mean if I measure the resistance between +ve and -ve terminals, it tells 10k ohms and keeps on rising. If I could find out anything on google it was some comparison between isolated and non-isolated converters. But I could not relate the info in my scenario. Any help would be great.
Edit: If I measure by keeping multimeter on 200k limit, it starts at 10k but if I switch it to 2000k limit, it starts from 100k.


texts: How tuning of particular FM signal is done?

texts:
I have a transistor radio which has facility to play FM radio channels between 88MHz to 108MHz frequencies. Now,consider a situation ,there are five FM stations which I can hear in my city 91.1MHz,93.3MHz,94.3MHz,98.3MHz and 102MHz.

Neglect all other signal like video signals,mobile phone signals, noises , distortions for a while. Consider that there are only 5 FM signals in the air. All of 5 FM radio stations will transmit their respective frequency components from their base stations and therefore at the antenna of transistor radio there will be sum of the 5 frequency components.

Now,  let us consider a function which contains summation of above 5 given FM signals present at the antenna. When I  try to tune my transistor radio manually ,the transistor radio has to choose only one frequency component from the above function.

Here, I want to learn how transistor radio does this with the help of frequency domain analysis. Can anybody explain the tuning of transistor radio using Fourier transformations for any FM frequency say 98.3MHz? How phase,amplitude and frequency parameters of each FM signal are taken care of while tuning a particular FM frequency say 98.3MHz?


texts: What are the disadvantages or advantages in using larger SMD resistors and capacitors?

texts: Are there tradeoffs associated with usinng SMD resistors or capacitors larger than a 0805 footprint? As the footprint becomes larger what considerations should be made?


texts: FRDM-KL25z assembly delay loop causes reset

texts:
I'm currently working on a project using the FRDM-KL25Z development board and programming using Keil MDK-lite (5.14a). What we're supposed to do is create a simple traffic light using three corresponding LEDs and a push button to expedite the light change(not immediately like a real traffic light but to check after each delay). The problem I'm having is my program works perfectly fine in the simulator but when running on the development board it reset itself almost immediately. I've narrowed it down to the loops I'm using for a 30 second delay. Any tips to find out why this is happening or how to find more information in the debugger would be great.

Here's a cutout of the loop I'm using.

reset   LDR R1, =0x00000002     ;Change light to red
        BL changelight          ;

        LDR R3, =0x00000011     ;Put value into counter (1 loop just to show code works)
 d30_1  BL buttonpress          ;Check for button press
        SUBS R3, #17            ;Subtract # of ticks in loop (17) from counter
        CMP R3, #0
        BGT d30_1

        CMP R6, #1              ;Check for button press
        BEQ reset               ;Reset to red if pressed
        LDR R1, =0x00000010     ;Change light to green
        BL changelight          ;

        LDR R3, =0x05B8d800     ;Put value into counter (5 seconds, the board resets when counter is this high)
d30_2   BL buttonpress          ;Check for button press
        SUBS R3, #17            ;Subtract # of ticks in loop (17) from counter
        CMP R3, #0
        BGT d30_2
        ...

Here is the branch buttonpress

buttonpress
        LDR R0, =0x400FF090     ;Put address of PORTC_PDIR into R0
        LDR R1, [R0]            ;Put value of PORTC_PDIR into R1
        LDR R0, =0x00000080     ;Put value of monitored input pin
        TST R1, R0              ;Check for button press
        BNE nopress             ;Break from process if button not pressed
        MOVS R6, #1             ;Put 1 in R6 if button has been pressed
nopress BX LR


texts: Wanting to power small audio amp toy with usb power bank

texts:
It uses 3 AA batteries but I'm looking to determine if I can either just use the usb 5v or find a plug & play method to adjust the voltage down half a volt.  I say plug and play because while I'm ok with soldering the usb output leads to the power input, I don't think I have the skill to add a resistor in that cable line or a board.  It's going into a helmet that already has a small power bank installed, so the weight and size of the 3 AA batteries is what I'm trying to eliminate.

Item shown here amazon.com/dp/B000XEYZFY/ref=cm_sw_r_cp_apa_xok.BbKTNHYBV


texts: What type of camera is compatible with the Arduino Uno in which its pictures can be saved onto the SD card?

texts: Researching interfacing a camera to the arduino, there is not a good amount of data out there.  Do any of you know the ways to do this and successfully be able to save the picture to the SD card for further use?  This is the best link I found so far: http://arduino.cc/forum/index.php?action=printpage;topic=50578.0 and it suggested the use of a ttl camera (~$50).  Is there any alternative (namely cheaper camera?)  The camera doesn't have to be high quality.  Thanks for your inputs!!!


texts: STM32 F103 GPIO software toggling too slow for 20 microseconds state change?

texts:
I'm designing an ESC for my hobby project but I got stuck on current chopping. I want to toggle a pin every 20 us and want to use a timer interrupt for this. On the oscilloscope I can see that timer output pin is capable of toggling even faster than this, but when I place HAL_GPIO_TOGGLE insinde timer interrupt routine the pin switches with 600 us rate (which is way too slow).
I really want to understand why is it so?
Also I would like to is it even possible to achive (and how) such toggling speed when when using state change in software?

And this is the code that drives the pin, called every 20 us:
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
       HAL_GPIO_TogglePin(UH_GPIO_Port, UH_Pin);
}

I could understand some delay but not this big.
I have already tried not using HAL_GPIO_TOGGLE but rather setting individual bits in BSRR register but i didn't see any improvement.
The ESC itself is designed right, because i can make the motor spin without current chopping (but power supply is in CC mode).
I'm using STM32  F103RB-NUCLEO board (8 MHz clock), but maybe i need to change to some other MCU. I know that they use atmega or silabs chips in commercial ESCs but I think F103 is perfectly capable of driving my circuit.


texts:
Want to use this type of connector https://cletk.en.alibaba.com/product/60724170404-804809515/Usb_Cable_Charger_Magnetic_Dc_Power_Cable_Connectors_Power_Adapter.html?spm=a2700.icbuShop.41413.12.141371b2bIt95e as a charging connector for my small battery-powered product. What would be the best way to fix it in my cases? I use two types of cases, one is CNC aluminum and the other is 3D printed resin. Thinking of some type of glue or epoxy, but do you have any specific recommendations that would work well in the long term? Temperature can vary from 0* C to 80* C (for short periods of time). No significant mechanical resistance required, besides what you'd normally expect when handling the product.

Thank you!


texts:
At this moment I'm working on a project that includes driving multiple LED interfaces. I've got 16 LED interfaces in total, each interface has two 5V inputs. One input for the high current LED drivers and one input for the digital logic. I kept the logic and load supplies separated due to the fluctuating current consumption from the LED drivers (TLC5940). The interfaces have a common ground, however I designed them so the LED driver grounds and logic ground are only joined together at a single point at the power connector. All the other LED driver and logic ground areas are separated from each other. The LED drivers from each LED interface are drawing about 1A each.

Now I'm not certain about how I should supply all those interfaces. Currently I'm thinking about this. I have four interfaces that are grouped together (so I have 4 groups) that I call 'units'. All the high current LED drivers from each unit are fed by a single regulated 5V/7A supply. All the logic sides of the LED units are fed by a single 5V/10A supply. See the image for a reference. Can anyone tell me if this setup (including the separation of the high current LED drivers and the logic components) is a good idea? Am I avoiding high current ground loops with this setup? If someone has any tips or tricks I love to hear them! Thanks for all your time!

In the image the left side of a unit are the high current LED drivers, ground separated from the logic components at the right side. Both grounds meet at the common power supply ground pin from the interface. The most right PSU is feeding all the logic components. Both the LED drivers and logic components are fed by a 5V PSU.

EDIT:
So as @Dave mentioned in the comments the design in the first image isn't a good solution at all. My first design looked something like in the image below. If I'm correct I won't have any ground loops between  the interfaces/main processor unit as the grounds are joined together at the power supply (I can call this star grounding, right?). With this setup I'm only concerned about the (possible) voltage drops on the 5V rail. Because the load can vary quite a lot, e.g. if all the LEDs switch on the current demand is increased with roughly 16A. Of course I decoupled the TLC5940's from each interface with some large capacitors. Besides that I forgot to mention that the logic is fed by a 3V3 (LDO) regulator which is connected to the 5V rail of the led interface. However I'm still concerned with the possible voltage drops on the 5V rail when the LED interfaces are driving all the LEDs. In practice would a setup like this with a large single switching power supply work? Or am I asking for trouble with this kind of setup? Thanks for the input!


texts: How much does it cost to prototype an analog IC?

texts:
There are many paper I see on IEEE website that claims they build their custom designed circuit on a CMOS process. Examples are 5.9GHz ring oscillator and 32-Gb/s serial link equalizer.

I know that IC fabrication can cost hugely based on chip area and have already seen this question which is very broad and targetting mostly digital world. So I wonder how much it cost for an analog circuit prototyping run on 90nm or 45nm CMOS process.


texts: Amplification Circuit for Generating High-Current Sinusoidal Signal to Feed a Coil

texts:
I am trying to implement a control algorithm using Arduino Due. I need to generate high-current constant-frequency sinusoidal signals to feed a coil using some batteries. The coil will generate electromagnetic force.

I want to design a circuit that amplifies a reference sinusoidal signal from the DAC0 and DAC1 of the Arduino Due and feeds the coils with the same-frequency but high-current sinusoidal signal. What is a simple, reliable way to do that?

The amplified current should be the same over a frequency range of the reference sinusoid, say 10Hz to 100Hz or some other range, and I want to generate the almost largest possible electromagnetic force.

I have two 12V Li-Po batteries but I can buy other batteries. I also have DC-DC converters if any needed.

There is no restriction on the frequency range. Basically, I have 3 coils and each coil can be fed with an arbitrary frequency but different from other coils. The resistance of each coil is approximately R=16 ohms and the inductance is L=0.070 H. The impedance is (R^2+w^2*L^2)^(1/2), where w is the frequency of the sinusoidal current in rad/s. I need about 3 A but I would like to get higher.

The coil is made with 22 AWG magnet wire with a polyamide overcoat as the material for current-carrying conductor of the coil. Multilayer multirow winding is used. Right now I have 500 turns and the radius of coil is 0.1 m. Max current about 5A and about 0.01 N force. Duration about 30 s.

Design Goal: A simple, reliable circuit that accomplishes the above force

Hope that I have provided enough information

Any help is appreciated.


texts: What type of rectangular chip is this? And how does one even know how to identify chips on boards?

texts: I have a two Playstation 5 boards which are identical, but one of these chips are labeled differently (C1 and A6). What are they and what do the labels indicate and how do I source this type of chip? And most of all how does one even identify chips in general? There are hundreds of different sizes and labels on chips, how does one even know what each one is called?


texts: I'm taking an intro electronics course, and we recently covered MOSFETs.  Would the circuit below work for controlling a 3W LED? Here is the part info. The LED wants about 1A of current. I'm thinking I can use the variable resistor to set \$V_{gs}\$ on the MOSFET so that it allows 1A to flow to the LED. For the 5V supply I have a computer power supply, so I could actually use other wires and get 3, or 12 V.


texts: Replacement capacitors for Celestion DL6 crossover

texts:
I have a couple of Celestion DL6 speakers that are more than 30 years old. Not quite as good as they used to be, it seems. I assume the electroytics deteriorate? In which case I need to replace them.
The values are 4uF and 6uF, rated for 50V.
So:
Should I replace with non-polarized aluminium electrolytics?
Should I choose another type eg film?
Any other comments or reccommendations?


texts: Finding average power signal and its calculation

texts:
Maybe I missed the critical section of fundamental of calculus. I don't get intuitively why finding average power is different if you separate the region like 1,2 and calculating the average of two then adding, versus finding the whole area then dividing the whole length. What makes it different? Isn't it the same process? Why do I have to divide 2 again to my calculated average?

Picture at the bottom summarize what I mean.


texts:
I recently got an otterbox drybox for my phone. I was sitting and thinking that its waterproof, crushproof, and big enough to fit what I need as well protective foam. I realized this would make an amazing project enclosure...

My only problem is that I can't get the wires out of the box without negating the waterproof aspect of the box. I was thinking to drill appropriately sized holes in the box, insert bolt style contacts, and seal it with a mix of silicone caulk and gorilla glue but im not sure if the mixture would be conductive...

normally I would just go with the idea but I figured I would ask if anyone has had this problem and solved it. I want it to still be water proof up to 100ft and crush proof up to 1000lbs (as the product is advertised to withstand) and I'm not sure if I have the right idea...

Question: How do I seal a project enclosure to be water and air tight using a non-conductive seal that can withstand greater forces than a grommet?

EDIT
A more specific description of what i am getting at seems to be in order... I want to use an Android device and an open source project called "IOIO" (a link to the landing page can be found here) to construct really any kind of unmanned, WIFI/Bluetooth/3G/4G/LTE/USB enabled, waterproof, and crush proof vehicle. Since submersibles are not out of the question, I got curious about maintaining the water resistance of the aforementioned product. With land vehicles being a possibility, crush proof sounds nice.

To answer a question from the comments which was what exactly I would need outside of the submersible to be connected. Everything expensive is exactly that, expensive. I will be using a relatively expensive android device, as well as the IOIO for each one of the products. Motors and frames and even overkill waterproofing can be made to happen cheaply if done correctly, but a $700 android phone is $700. So my desire is to protect the majority of the expense in a single well protected unit. (Just imagine the insurance package i can sell on my products if I know for a fact that there has been no significant damage to the real expense). So to answer the question directly, I would want to run circuitry from the box to all forms of input and output that may or may not be applicable to the intended circumstance.


texts: How to switch control between 2 RGB LEDs with PWM from a Netduino

texts:
I'm building a project where I will be lighting up 2 RGB LEDs using PWM. Since the Netduino only has 4 PWM pins (of which I will only use 3 - one pin each for the R, G, and B values respectively), I need a way to be able send the signal to either LED or both. Something like the following:

What component(s) do I need for that black box?  I considered something like a TLC 5940 PWM Driver, but I want to be able to power this off of the Netduino itself (i.e. no external power source). Do I just use a bunch of AND gates?


texts: Which ground plane shape is more appropriate in my application?

texts:
I've been working on re-making the two PCBs in the HP 211A square-wave generator from 1955, as the traces on the one I own are starting to peel off.
Focusing on one board, the multivibrator, for the purposes of this post, during the routing I was unsure if having a ground plane covering the whole 198.5mm x 133.5mm (7.8" x 5.25") area of the PCB was a good idea or not, as it could be just a big patch antenna.
So, my question is, at the 1Hz to 1MHz frequency range, would it be more appropriate to use a full ground plane as in "image 1", or a u-shaped ground plane in "image 2"? Lastly, for "image 3", as a sanity check, if I had a full ground plane, the traces I have going to the ground points to the sides would be unneeded, right? The AC would follow the path of least impedance and DC the path of least resistance, making the return traces in the third image useless? Would they make a ground loop as well?
The fourth image is a schematic. This board is everything within the red area except for the multiplier and symmetry potentiometer on the middle-right, which I've sectioned off with some red dashes.
For some additional information, my trace width is 1.5mm whereas the original was 1.7mm, and my spacing between the B- (-195VDC) and lower potential traces is on par or better than the original. (2.4mm or more, which is quite enough.) The trace width will be fine as vacuum tubes will draw very little current, 30 to 40mA give or take.
I’m aware that a star grounding technique would be ideal, but the original board used multiple ground points on the sides like this one, which will be held with screws and nuts to the metal chassis. I'm just looking to improve it where I can and understand how to best implement a ground plane into this 65-year-old design, though if anyone has better grounding suggestion than the ones I’ve presented, I’d be happy to listen. I’d prefer to keep my design close to how it is now, as it almost mirrors the original, save for the smaller and SMD parts.
If I’ve missed any pertinent information or I’ve been unclear about something, please ask and I’ll clarify as best I can.


texts:
I was given a Ceramics Kiln that is designed for 208V and I am trying to see if there is a way I can run it at 240V.  It has 6 elements made of 16AWG Kanthal APM resistance heating wire.  Each element having a resistance of 26 ohms.  Elements are wired in parallel pairs.
I tried changing the element pairs to run in series to reduce the voltage across each element to 120V.  This worked; but, the power reduction was too much and the kiln only got to 1100F.  Goal is at last Cone O4 (1945F) with stretch goal to Cone 6 (2232F).
My next thought is to try running the some of the elements at 240V.  This would be 9.2A compared to the 8A at 208V; but, I would really like to know if the wire can safely handle the 9.2A before I risk damaging the element wires.
How to figure the max current capacity for different gauges of Kanthal wire.
I have been looking for a while and I can't find anything.
Update: I ran a test with some of the elements at 240V and they did not fail; but, presently I am testing using a 30A circuit so I can't run more than 3 elements.  I have to move the kiln to a different location to test with 50A (which would allow me to run up to 5 elements.  This empirical test is nice; but, I would like to have some analysis to know how much margin I have.


texts:
I'm having trouble when I'm trying to make a voltage-follower from GL324 opamp. I use the following data sheet:

http://www.datasheet-pdf.com/PDF/GL324-Datasheet-LGSemicon-558557

And following connections:

I use 12VDC as Vcc. And above is a photo from my setup. If I apply 9V as input there is no output. If I apply reverse voltage with the 9V battery, I see minus reading from the voltmeter. And the opamp gets very hot. I double checked my wiring and it matched the circuit schematics and datasheet.

What could be wrong?


texts: OWON VDS1022i USB oscilloscope reading incorrect DC (and probably AC) voltages

texts:
My new oscilloscope seems to be reading DC voltages very wrong. Connecting it to a rasperry pi's voltage rail (which is usually spot on 3.3v) gives a reading of about 4.5v:

The probes are adjusted correctly (the 1kHz square wave has flat tops and bottoms, but is 5.6v rather than the rated 5v).
Testing a battery pack, measured with a multimeter to be 5.1v, gives 6.9v:

I have no idea what's going on!

The self calibration makes little to no difference, and there doesn't seem to be an option for manual calibration.

Here is the user manual (I have the 1022i version): http://files.owon.com.cn/probook/VDS_Series_User_Manual.pdf

Any ideas?


texts: Is it technically possible to divert a lightning into a moving vehicle as in "Back to the Future" movie?

texts:
In "Back to the Future" movie the characters try to power the time machine installed into a car by diverting a lighting.

They know that a lightning should strike the clock installed on a specific building at a specific moment of time. For the time travel to happen they need a huge jolt of energy and the car moving at 88 miles per hour. So they attach a thick wire (looks like a thick steel cable) to the clock and position that wire above the road at the height slightly greater than the height of the car, install a conductive rod onto the car and somehow connect that rod to the time machine.

They drive the car to the wire so that the lightning strikes exactly at the same moment when the rod on the car touches the wire and so the lightning energy goes into the rod and into the time machine in the car.

I always wondered whether this is practically possible (time travel aside of course).

I expect the following two problems:

for the whole thing to function the rod has to touch the wire at exactly the right moment and the electric discharge happens at about the speed of light which is damn fast TM, so precise enough timing can't be achieved without a computer but in the movie the car is being driven by one of the characters
when the lightning strikes the clock and runs down the wire it will likely ionize the surrounding air and discharge into the ground underneath the wire before reaching the road

The first problem can be solved by using a computer to drive the car. The second problem can perhaps be solved by insulating the wire everywhere except above the road. Neither seems to have been done in the movie.

Are there any other problems in that electrical setup? Can it technically work?


texts: Inverse Laplace Transform isn't A Contour Integral

texts:
I've learned about and used the Laplace transform in several signal processing classes and the inverse transform has always been defined as an integral like this:

$$ \mathcal{L}^{-1}\{F(s)\} = \frac{1}{2\pi j} \int_{\sigma_0 - j\infty}^{\sigma_0+j\infty}
F(s)e^{st}ds \quad \quad \sigma_0 \in \text{ROC}$$

I'm now taking a supplementary class on functions of a complex variable, so I've been learning more about integration in the complex plane. I'm a bit confused as to how the above integral should be interpreted. Is it a contour integral along the line \$s = \sigma_0\$ parallel to the imaginary axis? Does using an integral with endpoints rather than along a defined contour imply that \$F(s)\$ has an antiderivative so the contour doesn't matter?


texts: Solar panel, estimate power in various illuminating conditions

texts:
I'm trying to estimate available power from a solar cell like this one PRT-13781
https://www.sparkfun.com/products/13781

Includes:

1x Solar Panel - 2W
1x Barrel Plug Adapter - 3.5mm to 5.5mm

Features:

Monocrystalline cells - 19% efficient
Open Circuit Voltage: 7.0V
Peak Voltage: 6.0V
Peak Current: 378mA
Peak Power: 2.27 Watts
Four screws on back corners of panel allow multiple mounting options
Waterproof Urethane Coating
UV Resistant

Obviously, the 2W will be obtained in ideal conditions, clear sky, sunny, etc and at MPPT point.

How can I estimate available power for cloudy days, (variation with temperature will be also nice to know) etc. I cannot find relevant documents to start with, however, I will do at some point some measurements.

Until then, I am looking to best effort estimate just to have a start point in choosing the DC/DC MPPT charger, discharging the battery in my actual load conditions, etc.

For example this post question almost the same
How to estimate solar panel output as a function of solar radiation

but no relevant calculation based on illumination (lux) or percent of rated illumination vs. generated power.

EDITED
We can close this question, I finally found a very well documented answer here
How do I define solar irradiance in the context of a solar cell?

Thanks user @Russell McMahon


texts: High currents LED switcher circiut for WS2811?

texts:
I am making one High Amp for WS2811 RGB LED driver in range 2 Amp, SO  base on it's Datasheet the driver working by this way:

there are some switcher circuit similar to this :

But this kind of circuit how had 150 mA limitation, i need to more current for light power RGB LED's and  need led driver which is working with WS2811 IC outputs. SO what kind of circuits are proper for this driver?

Thanks a lot for your attention.


texts: What is currently the highest slew rate of any available op-amp?

texts:
Also, how is there a theoretical/practical upper limit to slew rates?
Suppose a customer wanted an extreme high speed op amp with a slew rate of, say, 5 Volts per femtosecond(which would translate to 5GV/μs)? Would that even be possible with a purely electronic op amp or would optics be required.


texts: How to choose the right potentiometer for dimming a LED

texts:
I have a reading lamp from IKEA. It has a bright LED. Too bright for my taste. So I inspected it and it is composed of a DC power supply unit that outputs 7V and a maximum of 3W. The LED unit is saying 1.5W.

My college memories tell me that this means that the LED is doing 214 mA at an equivalent of 32.7 ohms.

I am thinking to dim the LED using a potentiometer but I need to understand what resistance range should the right potentiometer have. If I choose a wide range the usable range within will be too short and I would have a hard time setting the desired light, choosing it too narrow it will not dim enough. I guess. Please correct any assumption that I make if needed.

Furthermore I remember that current vs light given by a LED is heavily non-linear. That means that if I manage to cut the current in half the light will not be half but probably 1/4 or even 1/5. If I'm not wrong again.

Considering that I would choose a potentiometer with a maximum resistance of the same equivalent resistance of the LED would that be a good choice for me?

I am aware this question might require editing and please provide comments that would help me pen the question better.


texts:
I've designed a simple STM32 board. Below are the schematic and pcb layout pictures:

Schematic:

PCB layout:

PCB layout with VDD hightlighted:

PCB layout with GND highlighted:

Only the parts of this design which are relevant to my question are shown in the above pictures.

My problem is: I tried to use the built-in ST-Link of a STM32 Discovery Board to program this custom board, but I couldn't succeed yet. The ST-Link Utility application on PC can recognize the programmer, but it cannot detect the target MCU. The errors messages I got were: "Target not connected" and "ST-Link USB Communication Error".

Here are some related facts about my problem:

The STM32 Discovery Board works fine: I can use it's built-in ST-Link to program it's on-board STM32 MCU. This is ok.
The STM32 MCU has been soldered with correct orientation on the custom board. I checked this twice.
I have checked VDD and SWD traces. They are connected well (no soldering problem). Pin Boot0 is at 0V. Pin NRST is at 3.3V.
The SWD cable is short, only 7-8 cm in length.
The STM32 on my custom board is of the same type as the one on the Discovery Board.
I have followed instructions in the STM32 Discovery Board's manual on how to use the Discovery Board to program an external STM32 MCU. To be more specific, I removed the 2 CN3 jumpers, and then I connected the boards as in this table:

I also removed the solder bridge SB11 on the Discovery Board (so that pin NRST can work properly).
I have tried both the ST-Link Utility app and Keil. The error messages I got are the same.
At first I didn't connect pin 6 on the above table (SWO) because to my knowledge it's not necessary. However after that I connected it as well, but things still didn't work out.
I also added a 100nF cap from pin NRST to GND, and then a 100k pull-up resistor from this pin to VDD. The problem still remains.
I've also tried to use the "connect under reset" mode of the ST-Link Utility program. No luck either.

I suspect that there might be something wrong with the design, but I'm not sure. Please help me to solve the problem.

Thank you very much :)


texts: What does this symbol (three connected triangles) mean?

texts: What do the symbols \$GD_{SN}\$ and \$GD_{SI}\$  mean? What is the component’s purpose? The second picture shows its schematic.


texts: Buck converter worked for 1000+ start/stop cycles with power from regulated DC power supply, failed with li-ion battery

texts:
I have a project which uses a TI step down converter (LMZ14201) to buck an input voltage (up to 41V) down to a regulated 5V. Until now, I had successfully used an adjustable (regulated) DC power supply for testing. In that setup, the step down converter worked like a charm.

Today I proceeded to assembling the complete system (i.e. using a lithium-ion battery pack, 36V, as the input for the buck converter). For testing purposes, I further connected a switch between the positive rails of the buck input and the battery.

With nothing else changed, the buck converter failed (produced sparks coming from under the package; thermal/GND pad?) on the second time connecting the battery. What could be the issue here?

I diligently followed the recommended layout depicted in the datasheet of the DCDC converter
I tested voltages up to 41.6V with the power supply. The aforementioned battery pack had 36V (approx. nominal voltage), the power supply is rated up to 42V (recommended) and 43.5V (abs. max) respectively
The input capacitance connected to the buck converter is 3x4.7uF. Apart from that, there were no input filter elements separating the battery pack and the converter

Could possible inrush current (caused by switching/input capacitors), paired with stray/parasitic inductance be the culprit here? If yes, a viable solution would be a series NTC current limiter. What other causes could this have, apart from random part failure?

UPDATE:
This problem is reproducible. Changing the soft start delay to 10ms did not help either. I managed to capture the voltage transient at the battery terminal. The battery voltage is about 37V, but it seems to swing up to 50V as soon as the DCDC is connected to the battery. The absolute maximum rating of 43.5V is therefore not satisfied anymore.

This does not seem to happen with just the input filter caps connected, but only when the input filter caps and the DC/DC converter IC are connected.


texts: I have need of a circuit that can sense the presence of a ~1MHz +12V -7V squarewave and switch inputs between this and +12VDC after ~15s when the wave is no longer present. I have been tinkering with using a 555 as a one-shot controlling a set of SCRs but it is less than elegant and decided to turn here to see if anyone has any better ideas. Much thanks.


texts: MOSFET switch with two on/off momentary buttons -- asking for critique

texts:
I want a "power button" that is actually two buttons; one on, one off.
This needs to switch on the order of 15 V and up to 10 A, for a LiFePO4 battery powered device.
I don't want to use a hardwired switch where this is mechanical, because I later also want soft (MCU-based) control of the same on/off functions.
I don't want to use a relay because 60 mA for a typical coil current is a lot (the typical load is perhaps 500 mA, but peak load on the device is 10 A.)

This is the best I could come up with. De-bouncing the buttons is not needed. When first connected, I think it enters "off" state because the gate is weakly pulled to ground through the load (output) -- and even if it isn't, the main power P-channel FET isn't going to have any gate charge.

I'm asking for two things here:

If you want to spend a few minutes helping out a poor n00b on circuit design, please critique this design and suggest whatever you think needs improving in this circuit. (Three FETs? really?)
If you think my diagram is hard to read (I got that last time :-) then please at least critique exactly what you think is poor about the diagram, so that I can better communicate in the future.

Thanks in advance for any help!


texts: Compensator for a specific damping ratio ζ

texts:
Okay, so I've been given a system to linearize and it gave me this result $$δ\ddot x+δx=δu$$ I tried state-space modeling this and this is what I got:

$${\dot x}=Ax+Bu=\begin{bmatrix}0&1\\-1&0\end{bmatrix}x+\begin{bmatrix}0\\1\end{bmatrix}u$$
Now, finding the eigen values of this I know that my transfer function will have the following denominator $$(s^2+1)$$ What I'm asked to do is design a compensatorC(s) so that the closed-loop system's dominant poles have a damping ratio of ζ=0,3.

I have solved similar problems but in these problems I also had $$y=Cx$$
Now what I'm having trouble with. The eigen values are the poles of the open or the closed loop system? Are they the poles of G(s) in the picture or the poles of the closed loop system? Because finding the closed loop transfer function of the diagram I will also need the numerator of the transfer function and not just the poles.

How do I proceed ?


texts: Klein mm100 multimeter failing to measure battery voltage

texts:
Sorry for what may be a super rookie question.

I have a Klein MM1000 multimeter. http://www.kleintools.com/catalog/discontinued-products/manual-ranging-multimeter

When I use the tool's 1.5 V battery mode on the 1.5V battery, I get about 1.5 V - as expected.

When I use the tool's 20V / 2V DC mode, I get "1", which, according to online, means the I've exceeded the voltage range.

I really just wanted to test my car battery, but I could not get a good reading there either.

Could the tool be broken or am I misusing it?

Thanks in advance.

Update - I also tested the fuses using the multimeter itself and they had connectivity, so I don't think it's a blown fuse.  I ended up just using the battery function of the multimeter to test my car battery, even though it was only 9 and 2V options (car batter is supposed to be about 12-13 V, mine was at 10).  However I still don't understand why I couldn't just use the 20V DC option.  Perhaps I need to take it up with the manufacturer.


texts: Headers nomenclature -- rows and positions

texts:
I want to but this kind of header -- essentially 6 pins, 3 in each row:

On the mouser search, there are parameters called rows and positions. I want to be sure what this would be called ---

2-rows 6-position (I think its this, but want to confirm)
2-row 3-postion


texts: How to deal with unicode characters with character LCD displays?

texts:
I would like to buy an LCD screen fom Arduino to display some results from a web http call; the Web API returns a JSON text encoded in UTF-8.

I've read that ICU is the way to go to handle Unicode in C/C++ programs for Arduino.

My questions:
Will I be able to display UTF-8 characters to this kind of screen?
Are there (affordable) character LCD screens able to display UTF-8 characters?


texts: I want to have an USB-UART interface for my Controller. I was thinking to use CP2102 and thus was reading the data sheet. But I cannot figure out the logic level of the UART part of CP2102. Can you someone please direct me to the proper section of the datasheet that says about this? BTW, the logic level of my Controller UART interface is 2.8V


texts: Why 90VAC from a synth's chasis that uses 12VDC PSU?

texts:
I have Korg's Wavestate synth. https://www.korg.com/us/products/synthesizers/wavestate/
It uses 12VDC PSU with two prongs, hence it has no ground pin. My power outlet is 220VAC. When I connect the synth to the power without turning it on, and no other cable connected to it, I can feel electrical sensation from the front metal panel. Of course, this goes away when the chasis is grounded to the wall outlet ground pin.
I measured the VAC between the metal plate and my hand with a digital multimeter and it was over 80VAC. The amperage between the metal plate and a ground pin from the wall outlet was measured at around 0.2mA AC. It wasn't high but I can definitely feel the electricity while operating the synth.
What I really wonder is how that 80 VAC comes out if it's powered from 12VDC adapter? I couldn't find any clue from my search.


texts:
I've been trying to improve my understanding of optimization of digital circuit.
With such goal in mind I've been studying from this book. I've been trying to understand mathematically the meanings of the definitions given, however there's some point I'm probably missing.

Below all the defintions that I don't understand.

  A data-flow graph \$G_d(V,E)\$ is a directed graph whose vertex set
  \$V={vi;i=1,2,...,n_{ops}}\$ is in one-to-one
  correspondence with the set of tasks.

Later the following definition is given

  A sequencing graph \$G_s(V,E)\$ is a hierarchy of directed graphs. A
  generic element in the hierarchy is called sequencing graph entity It
  then specifies

A sequencing graph is an extended data-flow graph that has two kinds of vertices: operations and links, the latter linking other sequencing graph entities in the hierarchy.
An example is provided

  Let us consider first a sequencing graph entity that has only
  operation vertices, e.g., a non-hierarchical model or an entity that
  is a leaf of the hierarchi. The vertx set VV is in one-to-one
  correspondence with the operations. The edge set EE models the
  dependencies due to data flow or serialization. The graph has two
  major properties. First, it is acyclic...

Basically I don't understand why it infers the graph in such example is acyclic, I've tried to review some of the background in chapter two in order to spot how the property is inferred. I can't spot why it should be acyclic. I was wondering if you could help me in understanding why we have the acyclic property or maybe pointing me out some further reference where I can solve my doubt. Mostly of the definitions I've seen so far for dataflow graph are actually the same of the one given in the book I'm mentioning.


texts: Switching input voltage, with two 3,3V inputs

texts:
I'm designing a circuit that can get its power from either a battery or a usb. The regulating of the battery and usb voltages is already done, and is regulated down to 3,3V.
If both supplies is connected at once, I don't want them both to supply. If both are connected, I only want the USB to power the circuit. If only the USB is connected, only the USB should power the circuit, and if only the battery is connected that should supply the circuit. How can I do this with ex. the use of MOSFETS or diodes? Thanks in advance.

simulate this circuit – Schematic created using CircuitLab

EDIT:

simulate this circuit


texts: What is the purpose of these capacitors?

texts: I have an amp (denon pma-1060) that has small 330pF ceramic caps directly soldered between it's speaker outputs and the chassis. But I don't know what is the purpose of them. Why are they there?


texts:
when we are debuging automatic breakpoint is coming near main.
how to resolve this issue.


texts:
I am building a high-powered flashlight using four Cree XHP70.2 12V LEDs, but just after the final assembly of the flashlight, they all started malfunctioning in some way.  See the images:

One LED is is half bright and half dim along a diagonal:

Two LEDs are half lit like this one:

And the last LED does not light up at all.  These are images of the whole assembly (with reflector removed):

All of that gray gunk is insulating thermal paste.  The blue dots on the corners of each LED are beads of silicone glue (in an effort to prevent short circuits through the exposed corners.) All of the LEDs are wired in series.

I've checked every combination of leads, and there are no short circuits.  There is also no conduction between the leads and the copper bottoms.  All of these LEDs used to work fine.  My best guess is that I somehow damaged them with excessive pressure after mounting the flashlight reflector on top.

Are there any better explanations for why each LED is acting the way it is?  How can I fix whatever damage has been done?

EDIT:

I tested each LED on its own, and they all work properly.  Somehow, the combination of all of them on the aluminum plate messes things up.


texts:
I'm not looking for product recommendations - I'm looking for advice on what different kinds of devices exist that would be capable of detecting the passing of an item of clothing on a rubber conveyor belt that runs on a heavy metal bed. The clothing is folded and probably at least half an inch high, and it can be any color. It's also dry and doesn't have any appreciable metal content

The device needs to be highly reliable in terms of its detection and longevity and simple to change if it goes wrong. It will be connected to a low power device; 3.3 or 5v gpio available on the device but if it needed more it could be powered separately. The environment is bright and quite noisy. I'm not averse to mechanical but wondering if something electro/optical would be better

I've considered IR based break beam but have a concern that they wouldn't reliably detect in the ambient light levels, and applying shrouds would then make them hard to align/risk they could stop working if knocked by a passion human

Laser pointer style optical detect is also something I've looked at and is good because it's easy to align thanks to being visible to the eye, but laser diodes only seem to be stated to last a low number of thousands of hours and I don't want a solution that needs a new component every X months - 5 years would be acceptable

I could possibly use image recognition and a camera looking at the belt; the belt is as far as I know a different color to garments but that isn't guaranteed, and it doesn't feel like it would be detection-reliable enough/would take too much processing power

Any ideas on anything else? So far a "long metal finger that presses a micro switch when pushed up by the garment" seems the best in terms of simplicity, but even for a micro switch rated at 1 million cycles, pressing it once every ten seconds it'll take about 3 months to reach those million cycles; a heavy duty one rated for ten times this might be required


texts: Can a 110VAC to 240VAC transformer be used safely in reverse?

texts:
We have a 110VAC to 240VAC transformer that we ship with equipment going from Europe to the USA. Can we use such a transformer in reverse to power US stuff here? By "can we" I mean "safely"?

In this specific case we have a Todd SU-13G autotransformer


texts: Using Differential Amplifier to reduce required RC values

texts:
I need to implement a low pass filter to convert a 20kHz square wave into a 20kHz sine wave. It would be nice to be able to use lower values, because in CMOS large resistors and capacitors take up huge amounts of space.

Is it possible to reduce the value of RC required to achieve a given cutoff frequency?

This paper  suggests that it's possible to hook it up so the cut off frequency is multiplied by the gain, allowing me to use smaller RC values. It states that the low pass filter makes the output of the entire circuit high pass. If I swap RINT and CINT, should this make the entire circuit low pass?

Below is my implementation, the output, and the expected output. I've tried it both ways round.

Is my idea possible, and where did I go wrong?
Thanks.


texts: Equivalent of S27c512-20A PLCC for project

texts: I've found interesting project for modification of an age old NMT Ericsson 430 Hotline mobile telephone to radio amateur station on 70 cm: https://web.archive.org/web/20040902185654/http://kotisivu.mtv3.fi/oh6mf/modif/ericsson/erics433/e433ohje/e433os1.htm (sorry, page is in Swedish, google translate can not translate link in a moment ). One of the first requirements for modification of telephone is to burn .bin file to  S27c512-20A PLCC  EPROM which is hard to find, is it possible to find equivalent for this EPROM?


texts: Is there any way to use an ac load ssr with a dc load

texts:
i have a s202s01 relay that i want to connect to my microcontroller. The problem is that the load i want to control is a DC source. Is there any way to make that ssr (3-24dc, 8A 250VAC) work with a 12v 0.5A DC load?

I haven't tried anything yet because i don't want to damage it.


texts: Cleaning power rail from switch mode power supply

texts:
In my circuit, I do not have control over what the power supply is used. Thus, I am preparing for the worst where a cheap noisy SMPS is used. I have some ADCs down the line that get their power from this so I don't want noise coupling to them.
Polling from different sources, I arrived at this circuit:

My approach is a choke + ferrite + RC filter. Would my approach be correct?
The choke I chose is this. I do not know if it's any good, though. I have chosen it primarily because it's small in size, and has 1k impedance which is fairly high (I have read that the higher impedance the better.)
For C5 and C6 as well I do not know how to calculate the values needed on those.
The reason for the ferrite is because of this paper same as choke I don't know what impedance value of the ferrite I should choose, I picked again a fairly high impedance value ferrite.
For the RC filter this is set to 3.3kHz low pass, although the components downstream uses 3.3V, I do not want to pull the voltage down too much.
Am I on the right track?


texts:
I am using the output of usb sound card as an input to PAM8403 ic with specs from datasheet. However i am using 4 ohm 0.5 W speaker. So i have tried testing with that and it works but sometimes with time volume starts getting slow.

Today i tried to put volume of pc at 72/100 to check the output. It turns out that after some time speaker starts getting heated and then burns in the center and back.

I am using same circuit as datasheet but low wattage speaker. As I have bulk of those speakers with me as well as PAM8403 IC, I would like to know if there is a way i can make these speakers work with the Amplifier...


texts: Combining two ideal voltage sources with an impedance between them

texts:
Solving a problem, I came across the following source transformation:

My question is:

I know that I can do the following:

But why can I do the first image transformation, even with an impedance between the two voltage sources?


texts:
I'm following an electromagnetics course and got this question as homework:

From earlier examples I tried to piece to together a solution but ran into some problems.
I learned that if the a circuit is switched off (after steady state has been reached) the voltage persists and a compensating wave emerges which counteracts the steady state voltage and after some time equals the old steady state voltage with a different sign so they add up to zero.
I also learned that after switching a circuit on, it will produce a wave with voltage amplitude equal to the 45V (since there is no internal resistance).

which would simply be 45V since there is no internal resistance.

Does this mean the voltage at z=0 t = 0+ (so right after switching) is the addition of the old steady state voltage plus the 45V of the new source minus some compensating wave voltage?

How do I find this value? I tried to calculate it considering only the switched off circuit and ended up with -13.5V but then the total voltage would be 58.5V. I also tried to simulate the circuit, according to which the voltage never exceeds 45V. But I'm not sure if Multisim accounts for the effects on a nanosecond scale.
Could you maybe explain to me the workings of a compensating wave after switching?

Edit to avoid confusion: I appreciate the help I'm already getting, but the reason I want to bring this question back to the compensating wave is that the next question is about its steady state. I'm not sure how I should decompose the voltage at z=0 into the voltage generated by the 45V source, the old steady state voltage and the compensating wave.


texts: Active LPF with cut-off frequency ~4250 Hz lets a 20 KHz signal through

texts:
I needed an active low pass filter for my project that can produce an output voltage within the required settling time and ripple voltage ranges. Although I managed to get a good enough output voltage with the shown resistance/capacitance values, if you calculate the cut-off frequency of this sallen-key LPF its around ~4250 Hz. The input signal however, is 20 KHz.
The sallen-key LPF:

The output waveform:

My questions are:
How does a LPF with a cut-off frequency of 4250 Hz lets a 20 KHz signal through?
Are cut-off frequencies, and therefore, stopbands of filters ignored in LTspice for some reason?
Additional info:
-op amp used in the circuit is the ideal single pole amplifier model of LTspice named "opamp" in op amps directive.
-input signal is 20 KHz 0-5 V pulse waveform with %50 duty cycle.
-if the op amp is switched for different models such as LT1001, the output voltage level is around a few pV. This still happens when the resistance and capacitance values are changed and the cut-off frequency is more reasonable. Example: 5k resistors, 1n capacitors, ~32 KHz cut-off.
Thanks in advance for the answers.


texts:
Can anyone recommend some alternatives to the teensy with capabilities to play multiple audio files.

I have a electronics project with a interactive game it is currently using a couple of button inputs a Li-po battery power source, NFC for detecting accessories, Bluetooth 4.0 for connecting to accessories, nrf24l01 for communication to a laptop, GPS and accelerometer, vibration motors for feedback and a small udisk audio module for playing basic sounds, this all runs off a arduino mega.

We have since decided to make some upgrades mainly to play multiple audio files so we can play effects and trigger sound over them at the same time to improve realism and may like to be able to play announcements over the existing nrf24l01 network to signal start if game and fouls ect.

The teensy looks perfect for this I only really need to play 2 audio sounds at a time but want to know what our options are as the teensy increases cost considerably could the stm32 handle this or perhaps another arm with an audio IC and sd card any ideas?


texts:
I have a CO/Natural Gas meter that requires a backup battery to be able to function (without beeping), even if it is plugged in.  I find that I am replacing batteries every couple of months (I have 4 in my house).  I am wondering if I can use a wall wart for the 9v supply.  I know that the 'backup in case of power failure' function would no longer be present, but that is not a concern of mine.

Better yet, can I hook up the 9v supply that comes with the unit (9v 400mA) to the 9v battery connector, so that the supplied 9v adaptor effectively runs both the unit's main power and it's backup?  I have opened up the unit and the soldering would be incredibly easy.

Thanks in advance for any options that may be forthcoming.


texts: Why does all the sensor registers from MPU6050 returns 0 to me? and why I can't write to the registers?

texts:
I would like to apologize before I start this question as I don't have the code to put down here as it is in my work pc.
BUT..
1)I have figured out that my GY521 Module (for MPU6050) has been correctly interfaced with the CPU ATMEGA32 that I am using.

SDA -> SDA

SCL -> SCL

Vcc for CPU as well as GY521 is being powered up at 3.3V

2)TWI interface works perfectly. I am using 6 functions for TWI Library.

TWI_START for generating start conditon

TWI_STOP for generating stop condition

TWI_READ and TWI_WRITE for reading and writing.

TWI_DEVICE_READ for generating a frame for reading data from register of the slave address provide.

TWI_DEVICE_WRITE for generating a frame for writing data to register of the slave address provide.

3)When I read WHOAMI register, it returns me the correct value ie 104d or 68h. I am able to write to registers , but when I read them back for conforming all I get 0.

4)After a lil working around I found out that the default state of bit 6 of PWR_MGMT_1 happens to be high ie in the sleep mode. I tried to write new vale to PWR_MGMT_1 but when I read back , I get the same default value ie 40h or 64d.

Now here I would like to believe that I have given almost all the description I could think of, if anything is left out do let me know please.

and I would appreciate any efforts made in order to solve my problem of initializing the mpu6050, reading and writing the registers and turning off the sleep mode.

THANKS :)


texts:
I want to use the ADS58B18 from Texas Instruments. This ADC is differential and the outputs can set to either LVDS or LVCMOS with programming an internal register.
I have a question regarding the clock inputs and outputs.
Lets say I am programming the ADC to use LVDS outputs. Is it still possible to clock the ADC with a LVCMOS signal or does it have to be a LVDS clock now?
Thanks


texts: Is soldering wires directly on a NiMh battery safe?

texts:
I'd like to know if soldering two wires directly on a NiMh battery is considered as safe or not.

My fear is that battery would explode (right in my face) because of excessive heat caused by the soldering iron. Other possibility would be the battery slowly inflating and then spreading toxic fumes (or corrosive materials) trough a hole (like a capacitor under excessive voltage).

The battery I want to use is made of 10 units of 1.2V (thus generating 12V)


texts:
I have two diode datasheets.
Onsemi
Vishay
In both the datasheets, why is the maximum allowable power dissipation of the diode not provided in the absolute maximum ratings table.
Usually, in electronic components, I have seen the absolute maximum ratings table which will include the maximum allowable power dissipation for transistors and other components. But why in these diode datasheets, the maximum power is missing?


texts:
Given that 0 <= R <= ∞  in the circuit shown, consider these two observations:

Observation 1: When \$R = 2\Omega\$ then \$v_R = 4V\$ and \$i_R = 2A\$.
Observation 2: When \$R = 6\Omega\$ then \$v_R = 6V\$ and \$i_R = 1A\$.

The maximum value of \$i_R\$ and the value of R that causes \$i_R\$ to be maximal.
I don't understand how to calculate the maximum value of \$i_R\$ and R. Could someone give me some pointers and hints to get me on the right track to solve this problem? I was thinking of calculating the voltage of open circuit and short circuit current using source transformation.

The maximum value of \$v_R\$ and the value of R that causes \$v_R\$ to be maximal.
Could somebody help me explain how to solve this problem?

The maximum value of \$P_R = i_R v_R\$ and the value of R that causes \$P_R\$ to be maximal.
Again, I don't understand what I'm supposed to do in this problem. If you can lead me to the right direction that would be great. I don't need you to solve the problem for me.

(Original image of observation text.)


texts: determine ir protocol without ir controller

texts:
I have the following issue:
I bought an ir controller for my Blaupunkt radio which has an built in ir reciever.The problem is that the controller does not works togather with the radio.
Its seem they use different protocols.I know how to decode an ir controller signals with arduino but don't know how to get it without controller.
The radio has an ST6285  MCU and reads the ir input on the FB port.
But further i have no idea how can i get to know the used infra protocol.

Thank you for your help


texts: Generating electricity with wet newspapers?

texts: For a project we're thinking of generating electricity out of wet newspapers. Is that possible? How much current would it generate?


texts:
I made an IR Proximity sensor but when I connect it to the battery the buzzer starts even if I have not brought anything close to the photodiode and IR LEDs.
Why is it happening? I checked my connections but there should be something wrong.
Its my first project so the soldering is not very neat.


texts: Controlling alternator load for peddle bike

texts:
I want to create bike-powered alternator system to recharge 12 V batteries.  People can only do about 300 W mex.

To turn an alternator with higher torque requirements, especially when the battery it is connected to has a low charge, won't work. Can I "trick" the alternator to be in a range that can be peddled by having a separate circuit branch between ground and the voltage regulator input terminal that would give me the ability put in a voltage independent of the battery?  In this way, I can adjust the alternator load requirements to match the maximum peddle power available.

I thought I could put a 12 V and 6 V battery in series with a rheostat connected to the ends and adjust the voltage output to the alternator.

I wonder if a second option would be to have different voltage diodes controlling a transister to give me different voltage outputs in 11.5 V - 15 V range.  I plan to have a voltage, current, current power and total power monitor on the line to give me the feedback I need to make this work.


texts: Signal to noise ratio for a non-physical property

texts:
The signal to noise ratio for a voltage, current, or power is easy to understand, but how do I calculate the SNR when the signal is not a physical property, but instead an abstract quantity?

I'll try and be clearer: I'm doing a theoretical project, and I have created a computer program that measures the solid angles that a simulated point subtends a number of simulated detectors. It then calculates the position of the point using these solid angles. I want to simulate what would happen if the detectors measure the solid angles with a slight inaccuracy. To do this I have added random numbers (between 0 and 0.01) to all of the simulated detector readings. I have called this noise, but I'm not sure if that is the correct term.

The detector readings can normally give a reading between 0 and 2pi, where 0 is when the point lies on the plane of the detector, but outside its perimeter, and 2pi is when the point lies on the plane of the detector, and in the center of detector perimeter. (They are 3D angles). This can be seen in this picture.

I want to express this noise as a signal to noise ratio. Can I just do:

$$0.01/2pi = 0.00159\%$$

Where 0.01 is the maximum size of deviation from the true value, and 2pi is the maximum size of the true value.

Here's another way to ask this question.

In my program the noise is simulated as:

$$Y=net(X+N)$$

Where \$Y\$ is the Position, \$net\$ is the function that maps \$X\$ onto \$Y\$, and \$N\$ is the noise.

I want to modify this function so instead of including \$N\$, it instead includes the Signal-To-Noise ratio. This is so I can do a sweep of the SNR to see how much noise my function \$net\$ can tolerate. How can I do this?


texts: What is the voltage drop across resistor in this circuit?

texts:
There is an example in the book 'The art of electronics - 3rd edition' that I can't understand. The issue is: How the voltage 0.6V goes to the diode D2 without a drop across R1.

This question is addressed here: Compensating the forward voltage drop of a diode signal rectifier.
But my main doubt (how 0.6V goes to the anode of D2) isn't dealt with.

In my opinion there must be some voltage across R1 and because of that the voltage 0.6V don't "flow" to the anode of D2.

Am I missing something here? The sinewave signal injected in 'in' doesn't generate a drop across R1? How the voltage that comes from 'in' can be added with the voltage on top of R1? If 'in' is high, e.g. 10V, what is going to happen?

In mind mind, I cannot figure how a voltage on top of R1 can be added to the voltage coming from 'in'. If 'in' is 10V the anode of D2 is going to be 10V and a voltage drop will appear across R1 (10V - 0.6V).


texts:
I am designing PCB a in which I am placing a BSP296 N-channel MOSFET, for switching solenoids:

MOSFET supply voltage is 24V
MOSFET  max power dissipation is 1.8W
Max operating temperature is 150°C.

I have done calculations as follows:

My operating temperature = 100°C (not taking maximum, I need info about heat sinking)

\$ R_{th} = \dfrac{(100°C -25°C)}{1.8W}\$
\$ R_{th} = \dfrac{75°C}{1.8W}\$
\$ R_{th} =41.6 °C/W\$

I would like to know how to calculate how many ounces of copper I need, what area of copper and if I need a heat sink for this.


texts: Equation for splitting a charge between n wires

texts: If I had a 10 amps of current that was split down two wires, one with 1 ohms of resistance and another with 2 ohms of resistance, what equation would I use to determine how much charge went down each wire?


texts:
I am working with an Atmel ATMEGA32U4 microcontroller - datasheet here with a 16 MHz crystal for system clock.

From my understanding, this chip has a 'Divide clock by 8' fuse programmed from the factory, effectively making my system clock 2 MHz. (Page 348 of datasheet. CKDIV8 (bit 7) default value is 0, programmed).

I would like to confirm my system clock speed, so I wrote some code to output a pin low, delay one clock cycle, and then put the pin high again. Measuring the time the pin is low should equal one clock cycle.

Here is the code I used to accomplish this:

//Set PORT E as output
DDRE = 0xFF;

asm volatile("nop\n\t"::);
PORTE |= 1<<2;

asm volatile("nop\n\t"::);
PORTE &=~ (1<<2);

asm volatile("nop\n\t"::);
PORTE |= 1<<2;

asm volatile("nop\n\t"::);
PORTE &=~ (1<<2);

A 'nop' is equal to one clock cycle, according to the AVR instruction set manual, page 108.

Based on this information, I would assume a 'nop' instruction to take 500 nanoseconds.
Is this assumption correct? (16 MHz/8 = 2 MHz. \$\frac1{2MHz}\$ = 500ns)

Here is a scope plot of my findings:

It would appear a 'nop' execution time is only 200ns (5 MHz)
I would expect there to be some additional overhead using C to set the port high/low, so 500ns is actually the minimum time I would expect the pin to be low. But as you can see from my measurement cursors 'a' and 'b', its not even close to 500ns.

Can anyone explain whats going on? Is there an error in my method? Am I missing something 'face-palming-ly' stupid? :p
Thanks for any help!


texts: Why don't solar cells produce visible light when supplied with electricity?

texts: ... A cursory Google search didn't reveal an answer...  Is the energy conversion a one-way process?


texts:
I'm looking for the easiest way to split audio, and I couldn't find a splitter IC. I'm using an MSGEQ7 graphic equalizer display filter that combines the two channels, and I'd like to have a splitter before it's combined so that I can have audio out. Any suggestions?

A bit more detail: I'm making an LED spectrum analyzer display that takes in a stereo audio signal and uses the MSGEQ7 chip to measure its amplitude over several frequency bands.

I would like to also provide an audio out connection, and just pass the input audio signal to it unchanged, while also feeding the same signal it to the MSGEQ7. That way, I could e.g. connect the spectrum analyzer between an audio source and a speaker system.

The trouble is that I've got both the left and the right input channel connected to the single audio input of the MSGEQ7. This means that a simple Y cable won't work as a splitter, since both output channels would end up being connected to both inputs.

I think I need something to split the audio inputs into two outputs, without allowing any feedback from the outputs to each other, so that I can connect one branch of each output to the equalizer without having the signals cross.


texts: Difference between i2c switch and i2c mux

texts:
I am working on a project which involves reading from multiple IMU sensors on i2c protocol. They have a fixed i2c address and hence I feel the requirement of some sort of multiplexer.

On some research, I found two components which appear to be doing same job. Here are the brief descriptions that these devices carry on TI website:

1) TCA9544A Low Voltage 4-Channel I2C and SMBus Multiplexer With Interrupt Logic

  The TCA9544A is a quad bidirectional translating switch controlled via
  the I2C bus. The SCL/SDA upstream pair fans out to four downstream
  pairs, or channels. Any individual SCn/SDn channel or combination of
  channels can be selected, determined by the contents of the
  programmable control register. Four interrupt inputs (INT3–INT0), one
  for each of the downstream pairs, are provided. One interrupt output
  (INT) acts as an AND of the four interrupt inputs.

2) TCA9546A Low Voltage 4-Channel I2C and SMBus Switch with Reset Function

  The TCA9546A is a quad bidirectional translating switch controlled via
  the I2C bus. The SCL/SDA upstream pair fans out to four downstream
  pairs, or channels. Any individual SCn/SDn channel or combination of
  channels can be selected, determined by the contents of the
  programmable control register.

To me, both appear to be the same. If anyone can point out the key difference between these two things, it will be really helpful.

Also, I want to ask what will be more suited for my purpose - I want to read the sensor data from all sensors at the maximum possible rate and stream it to a host PC or mobile phone using UART/wifi/bluetooth.


texts:
If you would take a c shaped iron bar that you would join together (with threaded ends with another threaded bar for example) and then wind in wire, would it act like like a toroidal magnet or still like a horseshoe magnet since there's still gaps?

EDIT 2019-03-04: I've replaced "ring magnet" by the proper term "toroidal magnet"


texts:
So I have set up a little experiment which involves a HDD BLDC Motor, a scope and a multimeter. Pretty simple, I know. Is it possible to determine the inductance of a phase by the voltage the phase produces? I would like to set up a model of the circuit in MATLAB or PSpice, but cannot do so until I find the inductance of one of the phases.

Unfortunately, all of the formulas I have come across involve the diameter of the wire and number of turns, however this is one electronic pressure fit case I would rather not destroy. I was hoping to figure this one out mathematically or even better scientifically. Maybe something that involves the rotation of the spindle vs. the voltage produces. Am I on drugs? Thanks for your help.


texts: Could you submerge any electronic device (with no applied power) and see no ill effects?

texts:
In theory, could you completely submerge an electronic device in water, let it fully dry out, apply power, and see no ill effects?

My logic: I can't see how how you wouldn't be able to do this. I understand capacitors and batteries hold charges, but if removed, they shouldn't be affected? Water damages components by shorting circuits and causing too much current and destroying components.

I am a curious senior in Electrical Engineering, so feel free to use big words or big insults in your explanation. Thank you! :)


texts: What is a safe way to carry around (wrt ESD safety) a single-board computer in an enclosure like this?

texts:
I have a single-board computer and an enclosure, which will hopefully look like this in the end:

I have three small questions:

If I only hold it from the edges while assembling the enclosure, do I risk ESD damage?
While the acrylic enclosure is on, will it be ok to carry it around by holding it from the casing?
What kind of additional protection should I use if I want to carry it around, e.g. in a bag (should I put it in some kind of box)?


texts: I was asked to determine the input resistance of the circuit in the figure, with and without channel effect. Is there a formula for that which could be applied or must I draw the small signal scheme and find it more rigorously?


texts:
I have a battery powered system that currently supports up to 5.5V input voltage (which amounts to 2-3 AA batteries in series.)

I'd like it to support up to 4 batteries in series (so up to 7.2V input so have some margin.)

What kind of circuit would you recommend to put between my input voltage and my system power input to allow my system to consume higher than 5.5V input without exposing my inputs to greater than 5.5V?

It's obviously very important that this circuit not put more than a negligible marginal quiescent load on the batteries (less than 100nA ideally.)

What circuits / strategies do you have up your sleeve to help me out here? Also of consequence, after functionality, is certainly marginal cost of the added circuit.

Update
In response to several of the comments, allow me to clarify.

  What current does your system take on full load and standby and at any other relevant time that you feel may be appropriate to mention? What is the minimum voltage your system needs and, is 5.5 volts an absolute maximum limit?

During standby the load on the battery is about 1 microamp. During full load, the peak current is around 150mA, but my 3.3V regulator (TPS63050) is capable of delivering up to 500mA. In principle it can accept an input voltage anywhere from 2.5V to 5.5V, and those limits are consistent with other components that are at the periphery of my system that directly interface with the unconditioned battery voltage.

  Are you serious about the 100nA quiescent current limit? How do you define quiescent...unchanging inputs? clock stopped? system went to sleep?

What I meant by quiescent in this case is that when the system is in its low-power mode, consuming nominally 1uA, I don't want to increase this figure by more than 10%, ergo 100nA, if possible. My survey of available switching buck converters suggests that's not a realistic expectation, the lowest quiescent current I've identified is the
TPS62745 at 400nA, and I could live with that.

However, is there a much simpler approach, like a few diodes in series with the battery voltage? Even at 1uA current draw, could they drop the voltage into range during sleep mode? Talk me out of that?


texts: Why doesn't wireless transmission and reception require a common reference voltage

texts:
so I have been struggling with this for a while now. I have tried to search for the answer but haven't succeeded yet. Here is how it goes:
If we take USART as an example for wired communication between two devices, the TX and RX lines are referred to a common signal(GND) so that a "1" transmitted is also received as a "1", which makes complete sense.
But when we go to wireless communication, how does a receiver interpret the incoming data correctly?
I know that electrical signals differ from EM communication. But why and how is a "1" sent is also received as "1" since there is no reference signal.
Any reference to reading resources would be highly appreciated!


texts: How is this voltage cutoff circuit working?

texts:
I am working on a project. I needed a voltage cutoff circuit. I found many online and I chose one of them.

Now I want to understand the circuit. Why is it working as it is? I dont know how to analysis it. My first thought was to approach it piece by piece, but I still dont know what is the best way to do that.
Please tell me the best way to develop sense of interpretation for such circuits which includes opamps and mosfets and etc.

Okay. Now i start decompose it. First part is about comparator. Here is schematics for it


texts: Cmedia CM118B USB Audio chip datasheet lacks application schematics. Has anyone experience using this or similar Cmedia chips?

texts:
I'd really like to use the Cmedia CM118B USB audio chip - it's dual ADC and DAC, so supports stereo speakers/headphones and stereo mic over USB. However, the datasheet lacks any application schematics whatsoever. The datasheet explains the function of each pin, but without being clear on how it's supposed to be wired up, leaving a lot of guesswork.
For example, pin 27 is "Microphone Input for Right Channel," with a complementary "Microphone Bias Voltage Supply for Right Channel (3V)" on pin 26. That is the full extent of the data on how to hook up the mic. Similarly with the headphone output, there is a left and right line out channel, and a 1.75v output for line out bias, no further info. If anyone has any experience of Cmedia chips I'd be thankful for any pointers.
CM118B datasheet


texts: Improving a Push-Button Debouncing Circuit

texts:
I'm having problems testing a 7490 decade counter, the switch sometimes toggles 2 or 3 counts (it's a pushbutton). This is already using this debouncing circuit I found:

(well great, I can't post images yet. It's an inverter that's connected to another inverter that feeds back the first inverter in a loop and is also the output. The push-button for the zero output is connected between ground and output and the one output push-button is connected between the two inverters and ground.)

Does anyone know any ways I can improve my mechanical switch toggling? An easy fix to the circuit I'm using would be ideal, but if that's not possible, what's a decent debouncing circuit I can use that works 100%? I just need it to be negative-edge triggered.

Help much appreciated

EDIT: Here's the image:


texts: Convert reverse-log taper potentiometer to Log/Audio taper potentiometer

texts:
Can I reverse the wiring on a reverse log pot to convert it to a log/audio pot taper?
Basically can I convert a "G" type taper pot to a "D" type taper -- http://www.bourns.com/docs/Product-Datasheets/91_95.pdf -- if I reverse the wiring.


texts: Whats a technique that I am not aware of to pull an AC cable through a conduit that is just a little to small

texts:
I have a lamp I am trying to rewire with one of those bendy necks

I can get the cable inserted 75% of the way through the conduit but then the cable and me don't have enough strength to keep pushing it through. Tried inserting a stiff rod to make sure it's completely straight.

Adding tape/heatshrink tubing to connect it to another wire makes it too wide to insert - even if you pull the wire apart and only attach to one side (to try to pull that through after getting the first wire through).

I could strip the wire back and twist it together with one that goes through but how far would I have to strip back to get decent strength? 1 inch doesn't cut it even with some tape

Or is there some better way to attach something to a wire without increasing its diameter?

I feel like I could compress the cable or try to shave some insulation off but that would be a fire hazard so am not going to try that.


texts: How to choose switched regulator and calculate the filtering (LC) corresponding

texts:
I'm a new user of switched regulator and I want to take one with ultra low noise and ripple (I'll also add a filtering, a ferrite, an armouring). But I don't know how to choose them.
I've understood so far, I have to choose one with high frequency switched regulator in order to get less harmonic and avoid big LC.
I've to choose a low noise regulator and check by LTspice the ripple and get them as less as possible.
But should I take some others parameters in consideration?

I'm also wondering how to calculate the inductance and the capacitance of a switched regulator.
I found these formula in a website, but it doesn't work well:
L=Vout*(1-D)dI f
with D=Vout/Vin and dI=peak to peak
C=2*dI/(8*f*dV)

Thank you for help


texts: How to easily find or create parts for Eagle schematic/board layout

texts:
For Eagle CAD software, during schematic or board layout, how can I search for parts/footprints already created by other people out there, to make my life easier? And if I'm still unable to find what I want, how can I create my own parts?

(Note: This question is intended as a reference for future readers, hence I am both asking the question as well as providing my own answer below based on the things I know. Perhaps others can chime in as well.)


texts: Creating DNF with variable in output column

texts:
I am trying to model an Arbiter in VHDL. For this I've created a Moore automaton and am currently mapping the output.

The output should be when mapping from the state:

z1 z0 | y
0   0 | 0000
0   1 | inB
1   0 | inA
1   1 | inA

So basically depending on the state z either inB, inA or 0000 should be passed to the output y.

How can I model this in a DNF? I would usually process by finding the y rows with a 1 in it, but here I don't know how to proceed.


texts:
Apologies because I'm sure this is an incredibly basic question and I've tried to work out the answer myself but I'm getting nowhere with it! I'm looking to get a powered trike attachment from my wheelchair, the website lists the run time for all different models as 1.5 hr so clearly this information isn't correct!

The model options are:

350 W, 36 V in either 8.8 / 10.4 / 11.6 Ah.

OR

500 W, 36 V in 8.8 / 10.4 / 11.6 Ah.

How can I calculate how long each one would give me as a run time?

I understand more Ah are better but I'm not sure if more W would mean more run time (because bigger is better) or more W would actually decrease the run time because it's drawing more power in a shorter amount of time? European manufacturers make these things with more like 1000+ W (don't know Ah, volts the same or 48) but the Chinese ones I've found are literally 10% of the price... I just don't want to find I make it to the corner shop then haven't got enough battery to get home and that's why they're much cheaper (but all that's affordable to me).


texts: MATLAB - FFT aliases occur sooner than expected

texts:
I'm using Matlab to analyze the frequency spectrum of a sample wav file.  In the frequency plot, I'm seeing aliases occur however they appear sooner than I would expect.

Here is the frequency plot:

Just using some quick calculations, the middle point of reflection seems to be centered around 3200 Hz.  This would imply to me that the sampling rate of this wav file must have been around 6400 Hz, however when I load the wav file into audacity, I am told that the sample rate was 11,025 Hz.

I am inclined to believe that this is correct and that the sample rate is 11kHz because when I check the properties of the .wav file, it tells me the bit-rate is 176k, which would correlate to 16-bit samples at a rate of 11k.

So what could explain this? Is it likely that the meta-information in the .wav file is incorrect? Or could there be another explanation?


texts: I need the name of a Hitachi TX26D60VC1CAB panels connector (picture included)

texts:
i have recently ventured into reverse-engineering this Compaq 420cxs panel. I have managed to find a semi-complete datasheet (more of a pinout-diagram) for it and with the help of an esp8266 based dev board, i made it display some colors.

But i would much rather drive it using a FPGA with the correct connector.
The only problem now is that i just cant seem to find the name of this weird connector, maybe someone on here can help me.

The connector has 31pins (yes 31, 16 on one and 15 on the other side) and a pitch of 1mm


texts:
Hello so my university is closed because of covid. I am allowed one day into their labs to build and test my WPT device.

My Tx is very large compared to my Rx. I have tested their inductance with a LCR meter.
The Tx has inductance 16.7micro H and the the Rx has 1.4micro H. I'm choosing a resonant frequency of 400kHz. That's because the capacitors for the WPT I have available are .01micro F for the Tx and .1micro F for the Rx.
All I have are the capacitors and the coils with wire soldered on. My university has a wave form generator and a NVA machine where some one will help me test WPT.
I was going to place the .01micro F in series with my Tx. The .1micro F in parallel with the Rx. Maybe a bread board for the Tx and directly solder the parallel cap to my Rx. I'm not sure about resistors at all...
My question is, I've never done anything like this. Is this the best way about building this simple circuit. I'm so worried my school is going to allow me in for one day and I'm going to come unprepared and not get any WPT or made a mistake somewhere. Any suggestion to actually building the resonant circuit. Also I know my Rx is very small and very then(I think 18micro meters), however in Maxwell software in ANYSYS, I have power transfer of like 80% at 70mm+(Also the simulation came up with slightly different inductance values but it was close). If I can get anything like that in the lab I will be so happy. Please any help of suggestions for building this circuit.