texts: Output the DC average value of a waveform

texts:
I have the task of designing a circuit that will, given a sine or square wave as input, output the RMS value of that input. I believe this task essentially has three parts

Squaring circuit
Averaging network (to get mean value)
Square rooting network

The first part wasnt too bad. I hooked up an AD633 IC with X1/Y1 as the input and X2/Y2/Z grounded. The part that I am stuck on is the Averaging network. I believe I need to do something similar to an integrator circuit however I'm not too sure what variations on that need to be made.

Anyone have any ideas? Thanks!


texts: If we dont know the channel coefficients but assume that we are sending a bunch of training symbols how does the receiver estimate the channel coefficients and how often should we estimate these channel coefficients?


texts: How do I determine how fast I can switch a load configured to high and low side switching?

texts:
I would like to switch a load on both high and low side. I would like to know the capabilities of the MOSFET switch IC I have chosen. Specifically, what is the highest frequency I can switch them? For my high side IC is the BTS7040 and the low side is the BM2LC105.
Since both of the IC use NMOS as a switch the circuit would look like this:

simulate this circuit – Schematic created using CircuitLab
I could not find an obvious specification in the data sheet on how fast I can switch these ICs Is there anyway to extrapolate this information?


texts:
I am currently doing a project regarding thermal energy harvesting using TEC Peltier modules and LTC3108 IC chip. This IC chip requires inductors that act as transformer to step up the voltage input. I constructed the circuit according to the website sourced datasheet of the LTC3108.

However, I didn’t get the desired output voltage.
The input voltage from the TEC is approximately 22mV.
Output voltage that I manage to catch is about 10mV.
I’m using Wurth electronics inductors (WE-EHPI, 1:100) .

Datasheet from Wurth electronics is not complete enough regarding primary and secondary winding, thus I’m not really sure how to connect it.

Is anyone have experience using this kind of configuration and can tell me what is wrong with my circuit?
Thanks in advance !


texts:
Can I measure one sensor with two PLCs?
I have a PLC that's part of a machine manufacturing stuff.

Another PLC is part of a robotic arm that needs to grab the piece.

It would be intresting to be able to read a number of sensors into both PLCs.

However I end up frying the sensors.

The sensor is a photovoltaic sensor that outputs a simple '1' (24V) or '0' (0V).


texts: What is the correct way to solve this problem?

texts:
I first solved it by converting the two star connected networks into delta networks and further solving them.
Then I solved by considering one star, converted that to delta and then used parallel series concepts.
If anyone can tell me what's the correct approach I would appreciate the help.
Thanks!


texts: Finding the total energy of the network in steady state

texts:
i got a network below in steady state im trying to find the energy in the network by the capacitors and inductors.

simulate this circuit – Schematic created using CircuitLab

My attempt to the solution was:

1) i open circuited the capacitors, and short circuited the inductors

2) i used nodal analysis, grounded the bottom node

3) i made Va at the node between the 2H inductor and the middle 3ohm resistor

4) Vb is the node between the 3H inductor and the middle 3ohm resistor

5) Va is 5V, i got my Vb to equal to 16/3V

6) now im stuck cus i do not know what to do next


texts:
I have built the following circuit both on a breadboard as well as Veroboard and both times when I power it up and apply a 1 KHz sine wave my output ends up very "noisy".
The resulting waveform still looks like a 1 KHz but zooming in using the oscilloscope shows a ~30 MHz sine wave imposed on it.
Another interesting thing is that when I probe the output of the function generator, that too has taken on this ~30 MHz oscillation. When the circuit is powered down however the output of the function generator looks like a clean sine wave. The filter was designed to have a lower cut off of 60 Hz and an upper cut off of 2.5 KHz. Simulating the filter shows that the frequency response is close enough for my purposes.


texts:
I am trying to replace the battery of a rechargeable LED torch, but it looks different than most others that I have seen. I was wondering if anyone can help me identify it, so I can try to find a replacement. Otherwise I'm thinking I'll replace it with an 18650 and a TP4056 (mini USB dc charging), but an in-place replacement would be good. It recharges from Mains power, if that helps. I opened a couple of others of different make but similar form, and they all had similar looking batteries.

The yellow caps are kinda like silicone I think, and not solid.
The battery voltage is ~3 or 3.5 I think, and the LEDs are very dull.
The source of the torch is India. But essentially Mains is 220V.

The battery is very similar to this 4V 0.5Ah lead acid battery


texts:
I am using the Atmel ARM M0+ MCU (ATSAMD20J18). I have written a bootload for it. The bootloader will check the first few bytes (lets call it magic key) from an external SPI flash memory to determine whether to enter the bootload mode. If the bytes are correct, it will copy data from the same SPI flash to the MCU's internal flash.

The problem is for the first time programming (for example in manufacturing), I need to have both the bootloader and the first version application firmware programmed in the MCU before we send out the product. Therefore I am thinking that I can program the bootloader to the MCU, and then using some method to program the external SPI flash with the application firmware and the magic key.

The question is how can I program the extenal SPI flash? I found a similar thread here:
"How do I write to SPI flash"
However, besides to write the binary format application firmware, I also need to write the magic key and the length of the application firmware to the first few bytes of the flash. I prefer to do In-circuit-Programming if possible.


texts: Why do circuit boards use strange paths?

texts:
First, let me say that I'm no electrical engineer, I'm just a curious student.

Here's a photo of a Raspberry Pi A+.

I (as one completely ignorant of PCB design) would expect the electrical paths to be as simple as possible, which normally implies using the shortest path from the source to destination. Here, the printer can clearly print straight diagonal paths, but some other nearby paths are stair-stepped, or even take bizarre roundabout paths to their destinations.

I've seen this on a variety of PCBs, including other models of the Raspberry Pi, some Arduinos, computer motherboards...

Can you explain, in layman's terms, why these more complex paths are chosen?


texts: MS5611 Barometer not working on PCB design

texts:
On a recent project of mine, I incorporated an MPU 9250 and a MS5611 Barometer on the i2c bus of an atmega 32u4.

The MPU 9250 works perfectly, but as soon as I solder on the MS5611 neither of them work.

Here is my schematic:


texts:
I am trying to extract carrier signal from amplitude modulated signal. The amplitude modulated signal is stored in a CSV file. I tried to calculate calculate carrier frequency by calculating the zero crossings. But the carrier frequency is not exactly same through out the period. it has minor deviation because of which exact carrier extraction is not possible. So I would like to write a PLL script and feed the amplitude modulated signal to extract the carrier. I found below code which would work as PLL.
% cosine output
c = 1;
% delayed cosine by one timestep
c_delay = 0;
% sine output
s = 0;
% delayed sine by one timestep
s_delay = 0;

% vectors storing the results by adding the samples one by one
sine = [];
cosine = [];
vco = [];
input_signal = [];

% PLL loop filter
b = fir1(100, 0.1);
% filter state because we just feed one value at a time in it and
% then come back to it every timestep so we need to save the state
zf = zeros(numel(b)-1,1);

v = 0;

% main loop: reading data one by one
for i=1:4000

% test signal, will be replaced by the input signal
% the PLL needs to lock on it, let's assume our
% frequency is 1% off. Should be f=0.1 but is f=0.099
% and we have some random phase angle.
  y = cos(2*pi*0.0099999*i+pi/2.345543);

%"voltage" controlled oscillator with f=0.1 +/- v input
  w0 = 2*pi*(0.01+v*0.002);
  c_delay = c;
  s_delay = s;
  c = c_delay * cos(w0) - s_delay * sin(w0);
  s = s_delay * cos(w0) + c_delay * sin(w0);

% phase detector
  p = y*(-s);

% filtering out the 2f term
  [v,zf] = filter(b,1,p,zf);

% let's save everything in handy vectors for plotting
  input_signal = [input_signal y];
  sine = [sine s];
  cosine = [cosine c];
  vco = [vco v];
end
subplot(2,1,1)
plot(input_signal);
subplot(2,1,2)
plot(cosine);

This code works fine for the smaller frequency of 0.1 Hz. But in my case the carrier frequency is close to 10kHz. If I change the center frequency to 10000 instead of 0.01 the code does not work. Can someone please help me to correct this code? Any new idea to extract carrier will also be very helpful.
Thanks!


texts:
How hot can my mouse get before it stops working? Assume the plastic is removed so it doesn't melt.

I'm really trying to gauge the max operating temperature for electronics that have no moving parts (ex. would the silicon circuit board melt at 1000 F?  Is there something else I'm not asking?)

EDIT: Must silicon be used?


texts: How can I project an oscilloscope display on to a wall screen

texts:
In the autumn I will be giving a talk to my local amateur radio club and I would like to illustrate it with live displays on my oscilloscope projected on to a large wall screen. I have tried this before with my Rigol DS1052E using their own software, Ultrascope, to get the display on to a PC, with the well established "blue socket" to project from the PC on to the big screen. Unfortunately there were two big problems. One is that there is a one or two seconds delay between changes on the oscilloscope and the PC screen, and the second is that use of Ultrascope cuts off the normal controls on the 'scope and transfers them to rather non-intuitive graphics on the PC screen. It was a complete flop, I could not control the scope in the tension of delivering the talk and the display that I relied on was a disaster.

Finding some programming examples on the 'net, I have written my own program to copy the 'scope data to the PC via a USB link, but I still find that it suffers from the same inevitable problems of delays and losing the 'scope controls, as does Ultrascope.

I have also tried using a webcam, a good(ish) one, Logitech HD720p to view the display, size 4.5 by 3.5 inches, but it suffers from poor definition at that close range; I could use it but it would be a last resort.

Please, has anyone solved this problem, or have any pertinent advice to overcome it? the purse is shallow, any solution needs to be reasonably cheap. If I buy another webcam, which would be the best?


texts:
I am looking to find a way to communicate an alarm on a tiny device with a very low profile low power consumption component. The alarm is binary in nature, basically it is either on or off.

LED does not seem to be the best option here because the nature of the alarm is such that it may go on for hours and I do not want to keep powering an LED for hours.

I was looking into the flip-dot components but I could not find any that is low profile. The tiniest ones I found are around 10mm x 10mm x 20mm. I do not have that much room for a very deep component.

I was thinking about e-paper solution. A very tiny 10mm x 10mm x 1m with only one binary cell/dot would totally work for me but I was unable to find such a thing with basically 1x1 resolution.

Any idea how this can be done with a very low profile component with minimal power consumption?


texts: Minimum PWM speed of a light to prevent flickering?

texts: I'm building a PWM controlled LED Panel, and am trying to figure out what the minimum speed should be to prevent any on-film flickering. How would it be possible to calculate this?


texts:
I am using an ADS1256 ADC chip (in the form of a Waveshare High-Precision AD/DA Board).

I am using a 5V reference voltage, but I can't seem to read full scale.

0V reads out -344 bits (~0V)
3.3V reads out 5559000 bits (~3.3V)
5V reads out 6698000 bits (~4V)

Can anybody advise on how I can read full scale? I'm using PiPyADC.

Thanks.


texts: MCU ADC and signal conditioning circuit layout

texts:
What are the rules of thumb for physical spacing of signal conditioning circuitry (say - some sort of high-speed sensor followed by a voltage follower opamp followed by a RC anti-aliasing filter)?

Should the RC filter be close the ADC pin?

I did see some noise injected the ADC pin, which results in various ADC sampling artifacts.

Note that this question focused on the physical layout.  Adequate precautions have been taken in the schematic design.  The firmware has been fully debugged.


texts: Are GX12 connectors in common use? Is there another name for them?

texts:
I have a project where I need to send NeoPixel data from an RPI "base station" to a neopixel art project. Both the base station and the art project are enclosed already.

Length is short, just a few feet.

I could just use a 3.5 mm connector, but that seems like a poor design choice as they are overwhelmingly used for audio signals. They can also short tip and ring to sleeve when inserted hot.

From googling a bit, I found the GX12 connector. These look really cool, sort of an industrial / steampunk type vibe.

However, I couldn't find these on mouser.

Are they in common use? Is there another name for these? Does mouser sell them? Can I find them for relatively cheap in the USA? What is a good source for these parts?

Or perhaps you can recommend another connector? Panel mount, doesn't short, has a cool industrial feel, just need power, gnd, and signal.


texts: What is the purpose of these coils in contactor auxiliary contacts?

texts: Can someone please tell me what the function of this module, and more specifically, the curley wires on top of this contactor? It looks like the wires go to the same terminals as the main contactor terminals (although I didn't test continuity to confirm), and from what I can tell, it engages at the same time as the contactor via connecting to the "buttons" on top. I tried to search Google but not knowing what to call it made that futile. The main reason I am asking is that the small curley wires are extremely thin, almost as if it served as some sort of a fuse. Any help would be appreciated.


texts: Replacing CMOS SRAM with equivalent TTL SRAM

texts:
I want to replace an IS62WV51216BLL-55 (http://www.issi.com/WW/pdf/62WV51216ALL.pdf) with an AS7C4098A-12 (https://au.mouser.com/datasheet/2/12/as7c4098a_v1.2-1288279.pdf), as the latter has much better speed (although less capacity, but that's not a problem in my case), to be interfaced with some STM32 I have lying around.

My question is, is the fact that the latter is a TTL part (but CMOS compatible according to the datasheet) a problem? I can see a table with the recommended voltages (and those are basically 5v), but the absolute minimum and maximum seems to be adequate (-0.5 to 7V).

Any other problems that might arise even if voltage is ok (according to the datasheets)?


texts: Using three phase contactor with single phase motor

texts: If using a contactor for 3 phase motors with a single phase motor, can just the hot (120v) line be passed through the contactor, with the neutral and ground bypassing it? I believed the concept for circuit breakers is applicable in this case too.


texts: Is there an easy way to physically implement a simple digital circuit?

texts:
I designed a digital circuit which, in total, has about 27-30 gates. Building that circuit in real life using a 74 series IC would mean using a lot of through hole/SMD chips, which wouldn't be feasible as I would like to fit that circuit in a small enclosure. I know how to program FPGA's (basic knowledge) using VHDL so I was wondering if there is a single electronic chip which I can program using a HDL so that I can create basic/small digital circuits without using tens of 74 Series IC's, but instead a single, programmable FPGA-like circuit? And what equipment would I need to program such a circuit?

EDIT: Preferably manageable packages, not a 100 pin smd package


texts: I want to create a stable 0-10 V DC output from a 3.3V PWM signal (arduino/esp8266)

texts:
I want to control an EC motor, but I have some difficulties with the motor's control input. According to my measurements it has a ~50kOhm input impedance, and probably also has an (unknown) RC low-pass filter.

My first attempt was a simple 2N2222 NPN BJT to amplify the PWM signal from the ESP chip from 0-3.3V to 0-10V.

Vout looks OK (measured with a DMM), until I connect the EC motor control input: then it pulls up the Vout to high voltages. (Eg.: in case of a 50% duty cycle, the Vout goes up to ~8V).

My assumption is: that the problem is with the RC low pass filter in the motor control electronics, which has a capacitor. As my circuits capable to sink much more current then source, the capacitor is not able to get rid of the charge it collected. If I increase the PWM frequency it gets worse. When I decrease R2, it gets better.

My current solution is that I replaced R1 with a 0-100k variable resistor, so I can dial down the charge current by limiting the base current on the BJT.

Now the circuit is working fine, but I have to fine tune the system every time if I want to - for example - attach an other/different EC motor control input.

Currently I am using PWM frequency 10kHz, because under 1kHz the motor behaved weird. (It was changing speed all the time, I guess after the internal RC filter there was still a huge ripple on the signal.)

So basically I want to create a DAC circuit, which provide a stable, regulated analog voltage output, even if there are RC filters or relatively high input impedance attached to it.

Can you recommend something? Maybe introducing an op amp, or is there any cheap DAC board that I can control with the ESP8266 chip?

Thank you in advance


texts: What is the process of going from machine code to electrically controlling individual transistors?

texts:
For someone who writes software but doesn't have a computer engineering background, the dozens of abstraction layers have always bewildered me.

I know all source code in their most fundamental level is broken down into 1s and 0s. I also know all CPUs at their most fundamental level are broken down into billions of transistors, and then logic gates & ALUs.

But this is where my knowledge gap stops:

1s and 0s -> ???? -> Transistors & Logic Gates & ALUs exist

All holistic answers filling that gap would be appreciated, especially if you can describe the process of deciding which specific transistors/units are chosen to do what work.

P.S. The answer shouldn't be a dissertation, as I realize this can go on forever. Just a succinct explanation/overview with keywords.


texts: Charge lower voltage, higher mAh with higher voltage, lower mAh battery

texts:
So let's hypothetically say we have a 12V 500mAh battery and we want to charge a 4V 2000mAh battery with it, using a (hypothetical) 100% efficiency converter.

One could say that, as the charge is constant in a circuit, one can best case scenario, charge the 4V battery to 25% of its capacity.

However, if one looks at it in energy terms, the first battery could provide, let's say 500mA for one hour @ 12V, this would be converted (with 100% efficiency) to 1500mA @ 4V, so it would (provided the 4V battery could handle the current) charge the 4V battery to 75% of its capacity.

At least one of these two statements is clearly false. I would like to know which one and why. Or if both then what is the real answer.


texts: What's the best tool to close a circuit on purpose

texts:
I have a PCB with some cheap SM switches (the ones with discs kept in place with adhesive tape or something like that).
I am using a screwdriver which is not reliable and I was thinking of something like a touch stylo covered with conductive ink. Is there something already on the market? I don't want to fix the switches, just be able to test the switch behavior.


texts:
According to Wikipedia

  PCI Express 3.0's 8 GT/s bit rate effectively delivers 985 MB/s per
  lane

985MBps * 8 = 7880MBps (63Gbps).

If I am using a 10Gbps Ethernet NIC with PCIe 3.0 8x interface and I am sending or receiving data at full 10Gbps line rate, I assume that my data between the OS and network card is being multiplexed over multiple PCIe channels in the motherboard slot my card is in.

Assuming that is correct, how does PCIe maintain packet ordering when multiplexing over multiple channels or is there no data ordering support? How am I getting 10Gbps of throughput with 8Gbps per channel?


texts: Cost-Effective CPLD micropower 1.8V from regulated 3.3V

texts:
in my design a ispMACH 4032ZE CPLD (32Macrocells) operates as SPI slave driven by a moderate 8MHz master-clock. The part requires a 1.8V core supply drawing (estimated) tiny 100uA over the full temperature range according to the data sheet.

A well regulated 3.3V supply which is derived from the  6V...8.4V board supply via an LDO is available on the board. Since the CPLD is the only 1.8V part on the board a full-blown LDO regulator seems overkill and I wonder whether there are more cost- and/or space efficient solutions.

The board supply range of 6V...8.4V seemingly rules out most affordable dual output LDO regulators, even 1.8V zener diodes are similarly priced. (0.3€)

The most cost effective solution seems to be a resistor divider (1.8k/1.5) plus capacitor... however this seems somewhat wrong for a power rail.

Any comments?

Remark

I recognize that there are cheap LDOs that would easily satisfy my requirements and which I probably will use for the sake of predictability and robustness. Still, my question aimed at the slightly uncommon solutions such as using LEDs for voltage dropping.

Many thanks!


texts: How to bias BJT base voltage in a push pull amplifier AND control current gain

texts:
I am building a motor driver and using the push-pull arrangement shown.

I need the output signal to be +/- 30V so each 'side' should be +/-15 and are balanced.

Cutting to the chase I can't get my head around biasing each of the bases, as you can see I am not amplifying the signal when I include a real transistor model.

The motor is Piezoelectic, 30V, 2W

Can anyone suggest a good source for design guides/equations?


texts: Task Execution time measurement on Keil for STM32F103

texts: Is there any builtin feature available in Keil uVision to measure execution time of a function or task for STM32F103?


texts: Power bank DIY Build (Regarding protection circuits)

texts:
I have been toying with the idea of making a power bank, as I have a few old laptop batteries lying around which are still working well. I plan to use these components:

Constant-current lithium charger with under-voltage and over-voltage protection
Battery Management System
CC/CV 5v Converter

Would it be advisable to use these components? I realised that most guides and power bank circuits lack a lot of these protection features. I'm not sure if it's necessary, as it will bring the efficiency down. Any advice is appreciated.


texts: How does the input circuit on this oscilloscope manage to accept such a large range of voltages?

texts:
I recently bought this ($45!) oscilloscope: http://www.gabotronics.com/development-boards/xmega-xprotolab.htm. Looking at its schematic, I see the circuitry for one of the two analog input channels:

The website says that the scope can handle -15 to +20V per analog channel. The oscilloscope is based on the ATxmega32A4U microcontroller. According to the website, each input pin can handle 1.6 to 3.6V.

It looks like the scope's circuit uses a voltage divider and then an op-amp. My question is this: How are circuits like these generally designed? For example, how are the parameters for the voltage divider and the op-amp's feedback resistor calculated?


texts: opamp single supply output AC (audio) voltage limit

texts:
I build non-inverting op amp with single supply voltage cca 9V. The basic scheme is shown in the figure below:

How to limit output AC signal if the base DC voltage is at half the supply voltage 4.5 V ( see the figure below).

I want output AC voltage to be max cca +- 2 V (lsl 2.5 V , usl 6.5 V "audio signal") to ensuring the stability of the next circuit. I dont want to clamp the signal i want to stop the gain at that voltage. How to do that?


texts:
I'm an electrical engineering student and I've been super excited to put a zvs induction heater together.

I finally got all my parts, turned it on, and smoked a MOSFET almost instantly.  Happened twice actually.  It's just one that gets hot the other seems to do nothing.  My work coil is about 2+2.  I originally tested it to be about .2mH but I took a turn out.  My choke started at something like 70mH and I took 2 turns off of that.  The caps are .1uF 1000V and the MOSFETs are irf540s.  I've tried troubleshooting on a number of sites but can't really figure out what I'm doing wrong.  Any suggestions going forward?


texts: Problem understanding when the OPAMP is switching

texts:
I have a problem with following oscillator circuit:

Assuming an ideal op-amp. I want to draw the output of Uout, Uc, U+.

First of all I want: \$Ua=f(U_+)\$

That is a simple voltage divider: \$U_+ = U_{out}\cdot\dfrac{R_1}{R_1+R_2}\$

After that I thought about what values can \$U_{out}\$ have and when?

\$U_{out} = 12V\$ when \$U_+ > U_-\$, \$U_{out} = -12V\$ when \$U_- > U_+\$

The capacitor will charge to \$U_{+}\$ because of an ideal opamp will hold \$U_D=U_+-U_-\$ to zero.

so with \$u_C(t=0)=0\$ I get:

\$u_C(t)=U_+(1-e^{-t/\tau})\$ with \$\tau = 9.1k\cdot100nF\$

So my question is first of all:

In case that NO energy is in my system, does it oscillate? -> Falstad shows an oscillation without any source connected (maybe noise?)
Since \$U_c\$ is decr/increasing to \$U_+\$, \$u_C\$ never reaches   \$U_+\$, so WHY does the Comparator-Output Change?
I thought that an Comparator works like this:

if \$U_+ > U_- -> U_{out}=Vcc_+\$

if \$U_- > U_+ -> U_{out}=Vcc_-\$

Maybe someone can help me to understand this? I have to learn a little bit more about oscillator circuits with opamps, so I have to learn the basic idea behind it. Hopefully someone can explain me that intuitively.

edit: I love it, maybe I got the answer myself after questioning.

\$Uc(t->\inf) = U_{out}\$ not \$Uc(t->\inf) = U_{+}\$

so there is an active case when \$U_- > U_+\$ so the Comp is switching.


texts: For how long ICs can be exposed to overvoltage without being damaged? (protection circuit evaluation)

texts:
I'm asking this because i'm trying to develop an active overvoltage protection circuit and unsure about how quickly it should react to overvoltage condition. Maybe someone can give me advice on that?

Thanks to everyone. I learned important things.


texts:
I am building a gimbal and passing I2C through sliprings. Right now I have 1.6Vpp spikes at about ~32kHz on the i2c bus. (The spikes are harmonics from motors which are driven at 16~17kHz).

The i2c bus is at 400kHz, so I believe I need a high pass filter to block anything below maybe 100kHz? How else would I clean the i2c bus?

I added an CR filter (cap in series, tried 1nF, 10nF and 100nF with 2k, 1k and 800R pull up) but the sensor wont even start with this modification.

I also added ferrites on both ends of the cable to kill any higher frequency spikes.

P.s.: it works perfectly if I pass the wires outside the sliprings with motors on and through the sliprings with the motors off.


texts: Driving a 2V LED from a 1V8 FPGA IO pin (MOSFET vs open-drain)

texts:
I would like to use one of my extra SDRAM bank pins to drive some LEDS. I was thinking about using a mosfet, but considering that I'm only looking at driving a LED, it seemed like a bit much.

So what about this? If I configure the FPGA pin to be open drain, then will this work? I did do a search around here but there isn't anything about this particular configuration. LED forward voltage is 2V typ 2V5 max. Led load current is 6mA.

Here is my backup MOSFET cct, but considering it's a 0.5W device, it seems like overkill for this particular application.

Mosfet on threshold voltage is 0.7V typ and 1V max, ID is 1A when VDS is 1v5, so I think that the 1V8 should turn the mosfet on enough. It looks like the resistance is ~1.5ohm, so it's definitely on enough at VDS is 1V8.

Which is better? Is there a reason why I should go with the mosfet, even if it's a higher-power device?


texts: Is there a simple circuit that outputs (min+max)/2 of a single-ended signal given as input?

texts:
I have a digital, single-ended, signal that randomly varies between +400mV (logical ‘1’) and 0V (logical ‘0’). I am looking for a circuit to calculate the DC value that corresponds to the average between the maximum value of the signal (400mV) and the minimum value of the signal (0V). So in this case, 200mV. Please note that this does not necessarily correspond to the mean of the signal, because if there is a sequence of consecutive ‘1’s, the mean will be higher than 200mV and if there is a sequence of consecutive ‘0’s, the mean will be lower than 200mV. I am looking for a simple circuit that will output 200mV all the time.

Is this possible ?

My circuit needs to consume as little as possible, so I’d prefer it be implemented using only passive components ...

I don’t know whether this is possible. Do you have any ideas ?


texts:
I have a 20V, 2 Amp Max, 10Hz sine wave generator, I would like to be able to connect a transformer to step up and down the voltage.

How would I go about finding a transformer that I could connect to this and step up by a factor of 10, or down by a factor of ten?

What do I need to look out for using a transformer at such low frequency?

I have purchased a Triad TCT50-03E07K and tried to connect the generator to the secondary and on the primary I saw looked like the transformer was saturating, the current would spike like I have seen before with saturated inductors and transformers.


texts:
I have been using op-amp TL072C in charge integrator configuration.
R = 1k Ohms and C = 100 uF.
Vin is a DC signal of 1 V.
VCC = 10 V and VSS = -10 V.
I get the expected output which is VSS, when a DC signal given as input.
But the strange thing is that virtual ground voltage increases to about 0.65 V after output reaches VSS.
Attached the screen shot.

Why does the virtual ground voltage increases after output reaches to -VSS or saturation voltage ?

Probe 3: Input
Probe 1: Output
probe 2: Virtual Ground


texts: Phase Locked Loop Frequency Multiplier x 100

texts:
Can someone please help me with selecting resistors and caps.

I have a PLL set up using a CD4046BE (PC2) connected to 2 x CD4017 decade counters to enable a x100 multiplier.

My input frequency range is 1Khz to 5Khz and I want to output 100Khz to 500Khz .

I have applied a few examples x10 schematics using 1x CD4017 which have worked well so my circuit is ok but it is the selection of resistor values and cap values for my low pass filter and VCO which I can't get right. I tried using some formulas and tables for the CD4046 but my math isn't great and the values I've tried haven't worked.

I have added my circuit with R & C values which enabled me to multiply an input of 1.2- 3.9Khz to 120-390Khz.


texts: How low can I make the source impedance of a PIC16F887 ADC?

texts: Microchip recommends 10K for the maximum source impedance of the ADC, but it says nothing about the minimum value. How low can I make the source impedance ? It is possible to damage something if it's to low ?


texts: Open Collector Circuit Needs Pull-Up Resistor to Measure Frequency?

texts:
I need a little help determining what I need in order to measure frequency from an Encoder containing the attached Open Collector Output.  The 5 Volts will actually be 24 Volts in my scenario (this is just the datasheet).

The device reading the output will be a NI cDAQ DI 24V Sinking Module.  According to the datasheet, the minimum "ON" Current and Voltage is 3mA/11V.  My thoughts are that I need an External Pull-Up resistor for wire Z and just read the period to get the Frequency.  From what I've read, I'll need 3939 Ohms to do what I want.

I_en = 3mA; I_lkg = 30mA; I_pullup = I_en + I_lkg = 33mA
V_out = 24V; V_IH = 11V; R_pullup = (V_out - V_IH)/I_pullup = 3939 ohms.

Am I doing this right or am I completely off and not understanding this at all?


texts: MC34063A - 3.7 to 1.5 buck converter voltage rises when load applies

texts:
I designed and created this circuit to get 1.5 V out of 18650 lithium ion battery cell (with protection board).

Circuit is built to use in a toy, so not a serious use.

It shows open circuit voltage as 1.575 V as expected. But rises to 1.7 when 6 Ω load is applied. Any idea why happening so?

Thanks

Updated: Added layout and actual circuit on board

I built this circuit on a piece of perfboard. Here is its layout:

Hers is actual photo of the circuit:

I poured hot glue after my above test so it would be not affecting the results.

All components except inductor are on top of the board. Inductor is of package CD43 and is positioned in exact location per above layout.


texts: What cell voltage should I use to charge a 2S 7.4 V LiPo battery?

texts:
My battery charger asks for a cell voltage. To charge to full, should this be set to 7.4 V or is the 7.4 V split between the two cells? If you know of any good resourses to look at on batteries that would be excellent.

Here is the battery I want to charge.


texts: Eagle cad dimension measurement showing on top and bottom layer when creating Gerber files

texts: I have an Eagle design as shown in the 1st image attached. The dimension measurements are on "dimensions" layer 20. When I create Gerber files then look at it in a viewer, I get the measurement arrows etched right on the board. It goes across the ground planes. I cannot figure out what I'm doing wrong. Does anyone have ideas?


texts: Trying to Identify this surface mount component marked 'J4S' on top

texts:
This is from the speed sensor circuit for a 1995 era Toyota Rav 4.

I have googled and the only thing close I get is a Schottky Diode.

Can anybody help?

Thanks,

Meric.


texts: What is the working and reactive power in this circuit

texts:
i need help with solving this task (it's on croatian but i will translate): https://ibb.co/sb0cnsx ,it says what is the the working and reactive power for the given cirucit (Xl = 3 ohm ,Xc = 2ohm R = 2ohm, u(voltage) = 100)?

I found the equivalent resistance for the whole ciruit, 1+2j, but i don't know how to find the active and reactive power in circuit.

I think formula P = I^2 * R could help me.

in the given answers(a ,b ,c ,d ,e) 'kap' means capacitive and 'ind' means inductive.


texts:
as an exercise problem in ARM assembly program, I had to convert a number x to its absolute value. now seeing the problem as a simple problem of removing the sign of the respective number, I used BIC instruction to clear the MSB sign bit. later  on I found out that RSBMI instruction is present in ARM to compute the absolute value of any number.

my query is that what is the difference between these two methods employed, does BIC and RSBMI present any different result in some cases? or if it can be done by just BIC then why add an RSBMI in RISC instruction set?


texts: Testing voltage continuity using a beeper?

texts:
I have a 48v rail and i wish to plug it into an audible oscillator to check for continuity when i am rattling the system under duress. What is the simplest circuit that i can plug into 48v to hear the voltage accurately?

I want an always on buzzer that makes a sound when it is running on 48v and that stops if the current is briefly interrupted.


texts:
I am analyzing ways to make a current limiting circuit, and here I'm having an unexpected problem. The schematic is as follows:

The problem I am encountering is twofold:

Even when node Vin is connected to ground, diode D1 still glows, albeit faintly.
Increasing the V5 generator up to 8V works, and the diode glows brighter linearly. BUT, the moment I go over 8V of input, the diode suddenly drops luminescence by about 80% (almost off) and stays there. The moment I go back below 8V, it turns back on bright, and falls off linearly as I decrease further below 8V.

Another remark: Putting the diode right below the transistor (anode at emitter, cathode negative opamp input) gets rid of problem 2). Problem 1) still remains.
As I understand, increasing voltage too much should make Q2 quickly turn on and off at high speed, regulating and keeping voltage constant, not drop it and make the diode go almost off.
The circuit is made to limit current to a value a bit over 20mA. When I go over 8V of input, the current suddenly drops to about 7mA.
VC = 12V
VE= Ground
Opamps are LM358.


texts:
I'm using a template USB HID bootloader from microchip\mla\v2013_12_20\apps\usb\device\bootloaders

and have made some basic modifications.  I don't have a strategy to be able to update the bootloader, however.  I can update firmware, but not the tool that I use to update the firmware if that makes any sense.  Am I just screwed if I ever make a mistake on the bootloader after releasing a product?


texts:
I've made the power circuit for my project with some protections.
(Fuse, Reverse Polarity, Undervoltage, working Vin is 12~24).
The circuit is supplied by user. Any voltage between 0~30 is acceptable and managed in power section of circuit.
The last problem I have is if the user (mistakenly or deliberately) plugs the supply to mains line (220 V). that's 220 V instead of expected 12-30 V Vin.
How to protect against Vin > 30v? (which most probably only occurs in case of Vin = 220 V).
Thoughts and info:

Varistors are not suitable here as they're slow.
Not sure if any fuse is fast enough to protect sensitive chips from microseconds of high voltage.
Can't find mosfets with high enough VbrDSS (Drain Source BreakDown) for high-side-switching.
Startup delay up to 5sec is acceptable if your solution requires it.
Using relays and/or optocouplers or any other switching method is acceptable.
Please don't mention labeling the device power jack, or anything that relies on user.

Thanks.


texts:
We are using inductors in 180KVA converter circuits.

To measure the inductance value of the inductor we are following the process of pumping the current up to 300A and voltage up to 30V.

After noting the values of voltage and currents we are calculating the value of inductive reactance and with this we are finding the value of L.  The value of inductances are 5.7 to 6.3 mHenries and 205 to 245 micro Henries.

Is there any other process for measuring the value of an inductors inductance?


texts: Shorting leads on centre tapped transformer

texts:
I have an audio transformer (SP-66) with a 1:1 ratio and centre taps on the primary and secondary windings.

(source: triadmagnetics.com)

Tests:
When I input a 6.5 kHz 8 Vpp sinusoid on the primary (pins 1 & 3), I observe an 8 Vpp sinusoid on the secondary (pins 4 & 6). (1:1 ratio).

Input on pins 1 & 2, I observe a 16 Vpp sinusoid on pins 4 & 6. (1:2 ratio).

Input on pins 1 & 3, I observe a 4 Vpp sinusoid on pins 4 & 5. (2:1 ratio).

My pcb is already soldered with the sp-66, and I need to double the output voltage.
I tried shorting pins 2 and 3 together on the primary to achieve a 1:2 winding ratio.
Instead, I still observe 8 Vpp, a 1:1 ratio.

Question: Why does shorting the centre tap on the primary to pin 1 or 3 still result in a 1:1 ratio on the secondary?


texts: Controlling heat gun's element: where to put SSR without disturbing motor

texts:
I'm working on a pet project of mine, creating a coffee roaster, where I'm using a heat gun as the heat source. To improve my control of the heat output of the gun, I've set up an Arduino to control a solid state relay (SSR), that in turn (if I get it to work) should control the heating element of the heat gun, by switching it on and off in intervals (high power => longer periods of on, low power => longer periods of off).

Now.. For this I bought a very simple heat gun with two settings - high (high temp, high fan speed), and low (lower temp, lower fan speed). I opened up the heat gun, and it seems that the motor circuit (AC->DC rectifier + motor) is using the heating element as a resistor(!). This means that I'm not able to isolate the circuit for switching heat on/off from the motor.

I've tried to make a circuit diagram (I'm not an electrical engineer, hopefully it's understandable anyway). I THINK I've managed to get it fairly correct.

In this diagram, the whole motor circuit including rectifier is the "M". The heating coils is divided into three. I've attempted to figure out the values as well by measuring and some calculations:

R_a is the largest and is used both on setting 1 and 2. I believe this to be 22 Ohms.
R_b is only used on setting 2 and is a small section of the same coil as R_a. Think this is 27 Ohms.
R_c is a thinner, smaller coil used on only setting 1 (lowest). I believe this is 26 Ohms.

(PS: Take the Ohm values with a grain of salt - but they seem to check out)

My question is: Is there any hope for me to connect my solid state relay to control ONLY the heating coils, without disturbing the motor? I don't really need the lowest setting - I'm going to use the fan on highest, and simply control the power to the heat coils using my SSR.


texts: Can AC harmonic quantities be expressed as a sum of phasors of different frequencies without confusion?

texts:
https://www.electronics-tutorials.ws/accircuits/harmonics.html
The problem with AC harmonics is that each term has a different frequency, being a integer factor of the first frequency. I was wondering if there was a way to conveniently express equations in AC harmonics in terms of phasors without any confusion. By that I mean, some additional detail would be added to indicate the frequency of each phasor so that it would be clear that they cannot be added together directly.


texts: USB ground loop isolation for multiple devices

texts:
I have a use case where I use JTAG debugger connected to the circuit under test. Circuit is powered from a desk PSU and measured via desk MSO. This would normally create a ground loop, so I use an USB isolator ADUM4160 based cheapo device.

Measuring resistance between un-isolated USB "ground" and PSU ground I get around 50+ MΩ. When USB-isolator is connected I am measuring 0Ω with my digital multimeter. Everything works fine, as far as my knowledge reaches.

Now, I want to throw two more USB grounded devices into a loop. Another JTAG debugger for second circuit that will be connected to the first one over serial port (sharing same PSU). Second USB device will be logic analyzer.

Can I connect USB hub after isolator and connect 3 devices into a hub (that will probably reduce the bandwidth substantially and wouldn't really work)?
Or do I need USB isolator per device ?

Also, I am running out of USB connections on the PC, so I will need to use the hub.

Is there any issues connecting multiple isolators to the hub?


texts:
It is easy to find BLDC motor manufacturers on google, but it is difficult to find PMSM. Maybe there is a terminology issue here.
There are many "Brushless Servo Motors" or "Synchronous Servo Motors" on google, do manufacturers use these terminologies to refer to PMSM motor?

In theory:
BLDC has concentrated stator windings and trapezoidal back EMF,  the controling method is called "6-step commutation".
PMSM has distributed stator windings and sinusoidal back EMF, the controling method is called "FOC".

In reality:
Most so called BLDC motors on the market have sinusoidal back EMF, and can be controlled by the same FOC method as PMSM motor. But I think they are still BLDC motor, not PMSM.

My question is:
Is "Brushless/Synchronous Servo Motors" more like the theoretical PMSM motor?
What does manufacturer call PMSM motor?

Thank you.


texts: How to define new component origin in EagleCad board view

texts:
I have been trying to rotate a component in my eagle pcb board mode but the centre of rotation has been defined upon one of the pins of said part. (potentiometer)
This is what I have done so far: I edit the component package and moved the whole part so that the centre is located in the middle of the part and save.
When I try and change package whilst in board view, the new origin has not changed and the part rotates about one of the pins instead of its central origin where I would prefer.
How is it possible to redefine the central origin of this component in board view please?


texts: Is there a protection needed in the mcu connected to SCR?

texts:
When an SCR is connected to high voltages (220Vrms) while it's gate is being controlled by pulses using a microcontroller powered by only 3V, is there a protection needed in the microcontroller?

My concern is that the mcu and my high voltage AC have common ground and I don't want any negative feedback in my mcu whenever there is a surge current or anything that may fry the mcu that is on standby on the the gate terminal. So do you usually add any protection on the mcu?


texts:
I have a portable solar panel capable of delivering 21W at 5V. I would like to be able to charge my 12V LiFePO4 battery with this panel. My AC-powered charge controller is rated at 14.4V 4A which I assume is used for rapid charging (CC) before switching to trickle charging (according to the manual).

After boosting my 5V supply to 14.4V my current is obviously limited and not going to make it to 4A. My question is whether this low-current charging would hurt the cells.

Tangential to this, does anybody recommend a boost converter or charge controller for this task?


texts: Why does a change in excitation of an alternator affect only kVA and not kW?

texts:
http://www.brainkart.com/article/Effect-of-Change-of-Excitation_12208/

The explanation is there but I feel too dumb to be able to understand it and connect it to the visual. Can someone explain it in another way? I get that they balanced out the voltages by subtracting from E2 and adding to E1 but I don't get why only the active component of the currents are affected. That leads me to not be able to understand the rest, but I do get that an angle change happens.


texts: Circuit works with power supply module, but not when connected directly with a battery?

texts:
I am fairly new to electronics and circuitry, and I ran into a small problem while trying to make a simple circuit on my breadboard. The objective is for the LED to turn off when the photoresitor receives light and turn on when there is no light. The circuit worked fine with the arduino power supply module until I tried to connect it directly to a 3V battery pack. I tried 6V and it did not work either. The problem is that the LED does not seem to be affected by the photo resistor when a battery is connected (always being on). Here is a picture of the circuit when the light is on with the power module:

Here is a picture of the circuit when the light is on with the batteries:

Thank you for your time.

EDIT:

This is the best schematic (first one) that I could make. I apologize if it is a bit confusing.


texts: Why doesn't MIPS allow us to use float immediate?

texts:
My teacher said that MIPS does not include instruction helping us to add a float immediate to a register because a float immediate has to be described by at least 32 bits.

However, I wonder what about an integral immediate to a register? An integer can be represented by any number of bits.

For example:

addi.s $f0,$f0,5


texts: can i control induction motor theoretically that it work on -in rated conditions- 3 phase supply but also it can be adjusted automatically by means of control to work at condition of unbalance or 2 phase or 1 phase also it can work with instantaneous variable load, is that possible?


texts: Regulate an RGB LED via PWM, both in brightness and in hue

texts:
I am looking to regulate programmatically an RGB LED both in terms of brightness and in terms of hue. So far I have learned that I can use PWM to do this, but I am unsure as to what the details are. I am trying to integrate this into an AVR project using an ATMEGA1284.

Things I know:

I will need 3 PWM pins
PB3, PB4, and PB6 are PWM pins on my chip

Here is an LED that I think I can work with. Here is another. Does anyone know if my goal can be accomplished? Further, does anyone have experience with using PWM with the ATMEGA1284?


texts: What kind of metal are RF shields made of?

texts:
With the shields typically found on WiFi modules, what kind of metal are they? Are they coated? Here's an example:

Thanks


texts: Processing ADC conversion result: DMA vs Processor Registers

texts:
I have a periodic ADC conversion (every 50 micro-seconds) and I use the result to do some further calculations and update the PWM load registers. The ADC is triggered by the up-down counter of hardware PWM and has to be done exactly at that time. I am using a Teensy 3.2 (ARM M4) and although it's a beast, I have to be as fast as possible with the ADC to be able to squeeze in the rest of the calculations before the next duty cycle starts.

The general idea to operate faster seems like using DMA which transfers the conversion results directly to system memory without involving CPU, which looks like

ADC_result -> DMA -> SRAM,

But after that I have to fetch the result back from the SRAM to process it, which looks like:

ADC_result -> DMA -> SRAM -> CPU -> finally getting processed.

Of course, not involving the DMA is way slower:

ADC_result -> CPU -> SRAM -> CPU -> finally getting processed.

My question is, since I have to put the conversion result into CPU to be processed anyhow, can't I just store it directly in processor registers without involving DMA or SRAM at all and process is right away?

ADC_result -> CPU -> finally getting processed.

There are a couple of points I would like to make to further clarify the nature of my issue and test any gaps in my understanding.

First, from what I have understood, DMA is mainly used when there is real logging to be done and we would to use the CPU in parallel, especially if the data providing peripheral is considerably faster/slower than CPU. This is not my case, since all the following calculation are dependent on the ADC conversion result and I have very little data being sent every 50 micro-seconds rather than huge chunks.

Second, there is no guarantee that I will be able to use processor registers freely, since they are subjugated to compiler optimization and might be totally ignored (using the register keyword in C).

I would love to hear any feedback on the matter, especially if my understanding is somewhat flawed or plain wrong.


texts:
So my question is: Can I transform the current source I1 with R5 into a voltage source? I know for sure that if R3 was not in between them I could, but does it make a difference? I am not sure.

Thanks.


texts: Function of temperature compensation (Tcm / tCom) Pin of MG811 CO2 sensor

texts:
I have the MG811 CO2 sensor and can use it in genrell. But for me the function of the temperature compensation (Pin "Tcm / tCom") is not quite understandable.

Here is the circuit of the sensor:

And the link to the Datasheet of the sensor itself.

Does the value serves for further processing in software or is it only used as information (Compensation already takes place in the hardware)?


texts: What's the difference between switching speed and gate delay for a transistor?

texts:
I'm accustomed to seeing clock speeds on computers in the 1-5 GHz range, or 1.0 to 0.2 nanoseconds (1000 to 200 picoseconds (ps)). This has generally meant that, depending on complexity, logic gates are operating at 5 to 20 times that fast. So a 5 GHz system clock might used for a path of logic with switching times of 40 to 10 ps.

In a 2002 paper on FinFET devices, I see transistor gate delays like "0.34ps for n-FET and 0.43ps for p-FET."  Admittedly, these are aggressive numbers, but this is an order of magnitude smaller than the switching times I am imagining.

This leads to me believe that transistor-level switching times and gate delays are not the same thing.  What accounts for the difference?  And do I have very bad assumptions somewhere?


texts: Two different ways to open a project in IDE's for MCUs

texts:
I am using following 3 different IDE's for ARM based MCU's.

TI's CCS
ST's CubeIDE
IAR's Workbench

I have to move the entire projects which are build on each of these IDE's on different PC's from time to time.
One thing I have noticed is that I can easily open an IAR project when I move it on another PC by simply double clicking on its .eww project file but for CCS and CubeIDE projects I had to go through the File->Import steps in their respective IDE's.
It works but I am curious why these two IDE's have entirely different way to open a project which was build on some other PC?
Is it possible to open a CCS project or a CubeIDE project just by clicking a single file.. same as in the case of IAR? In IAR when I double-click its .eww file then it open the entire project in the IDE and setup the folders all by itself. If I trying to figure out a similar way in CCS and CudeIDE.


texts: In Eagle, how can I create part variants with and without an exposed pad?

texts: I have a part that's available as a TSSOP or as a QFN with an exposed thermal ground pad. I want to create a variants in Eagle for both packages. How can I show that the EP pad should be connected to GND without creating a new symbol?


texts:
I am looking to build a circuit that will control a 120v battery charger through a relay, the circuit should turn the relay on when the battery goes below 11 volts and turn off the relay when it gos above 12 volts.

I also need to be able to adjust the "trigger" voltage. maybe 10 volts through 11 volts.. incremented by a tenth of a volt..

what this does is charge a 12v battery when the voltage goes below 11volts.

Currently I am doing it with two ebay purchased circuits and some fancy relay wiring.

circuit one trips a relay that is normally open to normally closed when voltage goes below 11 volts.. circuit board two when "triggered" by circuit board one closes it's relay for 60 minutes.

That relay (circuit bard 2) runs a 120v 30 amp relay that turns on a 100amp 12 volt power supply which charges 8 100ah deep cycle batteries.

I have the delay circuit boards (board 2). I can not find board 1. So I thought I'd reboot my teenage circuit making skills, but I can not seem to find a diagram to accomplish this..


texts:
Why do banana plugs need these holes?
Why do banana plugs need these holes?


texts: What is PWM Dead Band and when should I use it?

texts:
I'm having trouble understanding this concept, here is what the documentation in my microcontroller says about it:

  dead bands are defined as the number of PWM clock ticks from the
  rising or falling edge of the generator’s OutA signal.

Google gives me this diagram, which helps a bit:

However, I can't see a purpose of doing this. What does it achieve?


texts: How to combine a voltage and current booster in one circuit

texts: I am trying to design a voltage-current booster stepping voltage and current from 2.5V-15V and 2mA-2A. I have searched quite a number of sites but each of them is giving a different design and it caused confusion. May you at least give me a head start where to specifically start with the design.


texts: JTAG boundary-scan test software to view and control pin states

texts:
What inexpensive or free tools could you recommend to view and control pin states via JTAG boundary-scan?

I'm aware of full-featured boundary-scan products that cost tens of thousands of dollars and used in manufacturing houses mainly. I want a simple inexpensive tool to occasionally check few suspected pins if they are soldered correctly; to light LEDs on a board without writing any firmware for MCU/CPLD/FPGA; to see if pressing a button on a board changes the appropriate pin state, etc.


texts:
I see LTspice has an Icrating parameter for BJTs. As far as I can tell this isn't part of SGP (SPICE Gummel-Poon model) and also not present in other flavors of SPICE. So what is Icrating good for? It it used in any way by the program, or is it for user information only? I'm guessing you could for instance script it (say via .MEAS) to find if some BJT exceeds its collector current rating, although I haven't seen that done.

Obviously that determines what goes into the [max] Ic column.

Is that all there is to it?


texts: LED Light Bar set up, through cigarette lighter

texts:
The below image is the setup I would like to have in my car.

I tried to illustrate it as best as i can. I do not want to go straight to my car battery for warranty purposes.

So my questions are:

What size fuses do I use and where do i put them? I am able to insert a fuse at the cigarette lighters.
What size wires must i use?
Is there a better way?

Please feel free to edit the image.

Thanks

I hope there is enough information


texts: Integrated 5V uninterruptible power supply (UPS) with a lithium cell?

texts:
I'm trying to figure out the best way to implement a UPS for an embedded system that runs from a 5V supply.

Essentially the system has a 48v to 5v, 1.2A output DCDC converter that powers my system. The 5v output supplies a bank of relays, as well as a 3.3v regulator for the embedded side of things.

When the input power fails I need to be able to keep the system alive (both 5V and 3.3V rails) for about an hour or so, and I figured the best way to do this would be with a lithium cell charger, and and boost converter. The average current of the system is around about 200mA so I know a single 18650 Lithium cell should more than suffice.

To reduce design time and complexity I hoped to find a highly integrated one-chip solution for this, but I'm unsure if it exists. If it doesn't, I don't know what my other options are either. I figured this is essentially most power banks do, so surely there must be a simplistic solution out there somewhere... I just don't know what to be searching for other than "lithium battery charger boost 5v"

Can anyone with some experience in this area please point me in right direction?


texts: How is phase angle calculated in an RLC circuit?

texts:
If I have a source with a phase angle, like this

how may I count the phase angle of the voltages and currents across all the components, as well as the returning current? What is the angle between voltage and current at each component, as well as between source voltage and returning current?


texts:
I have 2 devices, a Spartan 3 and a Spartan 6. I am trying to configure both of them through JTAG.  One way to do this is to daisy chain the devices and use boundary scan. However , one thing I still don't understand is how do I select which device in the chain I want to program in Xilinx? Where is the option for this?

Second this is a proto board and the focus is on the ease of debugging. Will daisy chaining like this cause problems? Is there any easy way to put a single jumper to switch the JTAG pins between FPGA's or is it better to have 2 14 pin connectors and keep removing the programmer header and putting it back in?

What exactly needs to be done at the PCB design level? Is shorting the TMS,TDI,TDO,TCK from different FPGAS sufficient ?


texts: Antenna size used in wireless morse communication

texts:
Pardon my ignorance, but regarding morse coding I came across the following information:

  The radio frequency of 500 kilohertz (500 kHz) has been an
  international calling and distress frequency for Morse code maritime
  communication.

Does that mean all morse signals sent with a carrier RF signal fixed at 500 kHz frequency?

Another information I know from the antenna theory states that the transmitter antenna length should be at least 1/8 of the propagated radio wave.

It seems the wavelength for 500kHz radio wave used once in wireless morse communication is 600m.

This requires an antenna length at least 75m.

Is my conclusion correct or did/do they have another workaround for a smaller antenna?

EDIT:

  The electrical generators and radio equipment on board the Titanic
  were the best available at the time. The wireless equipment was built
  by the Marconi Company, the dominant provider of radio equipment and
  radio operators at the time. Powered by a 5 kilowatt motor generator,
  and backed up by an emergency generator and batteries, the ship's
  radio had a guaranteed range of 250 miles under any weather
  conditions, and could usually maintain communications over 400 miles.
  The antenna system for this radio equipment can be prominently seen in
  most of the clear photographs of the ship. It consisted of four wires
  strung between two masts, the forward one located about ¼ of the way
  back from the bow of the ship, and the other being near the stern. The
  height of the antenna was 205 feet above water level. The antenna was
  fed by four individual wire feed lines, which appear to emerge from
  the radio room in front of the first of the four large stacks, or
  "funnels" of the ship. The feed points appear to be located
  approximately 1/3 back from the leading end of the antenna.

source: http://www.avsia.com/djohnson/titanic.html

  One of the first uses of T-aerials in the early 20th century was on
  ships, since they could be strung between masts. This is the antenna
  of the RMS Titanic, which broadcast the rescue call during her sinking
  in 1912. It was a multiwire T with a 50 m vertical wire and four 120 m
  horizontal wires.


texts: What is the difference between optoisolator and motor driver?

texts:
Suppose we need to control power of a device (12v, 500mA).

I tried to use TLP281 board, which works, except that it inverts the output: device is powered  when there is no control signal.

For this reason, the TLP281 board is not useful in my project.

This is picture and schematics for TLP281 board:

I need an optoisolator board which works analogous to normally open mechanical relay: when
there is no signal, device must not be powered; and when
there is signal, device must be powered.

I consider to use ULN2003 arduino board instead of TLP281 board. Is ULN2003 supposed to be used as a relay at all?

NOTE: workaround by inverting the control signal in microcontroller firmware is not permitted, as the device must not be powered when microcontroller is off


texts:
https://wiki.microduino.cc/images/f/f7/MSK-12C01(1P2T).pdf

Is this a 3 pins spdt switch? or 2 pins. If it's a 2 pins switch, which 2 are the connected one.


texts:
I have a circuit where I am using a SIM900 GSM/GPRS module. As per the datasheet it needs 3.4 V - 4.8 V and upto 2 A of current. I am using LM2576. The input to the regulator is 12 V & 4.2 A and output (which is going to SIM900) is 4.175 V. I have connected leds for NETLIGHT and STATUS LIGHT. I have connected a switch between PWRKEY and GND to start the SIM900. Following is the schematic of regulator:

SIM900:

The problem I am facing is as soon as I press the switch S1 to turn on the SIM900, its netlight led starts blinking and status light led is always off. What does this means? Is the module faulty? How can I debug it?

Datasheet


texts: What is the purpose of the spring used in point-contact transistor?

texts:
Below on the left side of the illustration there is a point-contact transistor which is the first transistor invented in 1947:

It seems the symbol of BJT actually comes from this point-contact transistor even though they operate very different way.

But what is the purpose of using a "spring" for establishing contacts?

In this source it is written:

  The whole triangle was then held over a crystal of germanium on a
  spring, so that the contacts lightly touched the surface.

Is that the reason for using the spring? To ensure a weak touch to the germanium surface? But if so, why is a weak/lightly touch is needed?

Edit:

Another source from page 201 of the book called "Conquering the Electron":


texts: Different capacity lithium polymer batteries in parallel

texts:
Is there any problem if I put different capacity,from different manufacturer with different specification? This is my current configuration:
DW01 Protection Bord is being used on both. But power bank circuit also contains protection circuit.


texts:
I have learned about page write operations from App notes and data sheets of EEPROM chips.But i want to clear certain doubts.
I have an EEPROM chip which got 32KB and 64B Page Size.

1.Can i Write less than 64 Bytes?
 Say  n Bytes

If yes then What happens to the remaining locations(64-n) in case of Page write?(Will it Stay OxFF or turns 0).

This is the EEPROM chip 24LC256.


texts: Why does this buffer apply a DC voltage through a high pass filter to the output?

texts:
simulate this circuit – Schematic created using CircuitLab

What is the purpose of C3 and R5 in series between +9v and the Output? The only thing I could think of is that it supplies additional current, but I don't understand how it could supply current though a capacitor.

This circuit is the buffer that was in Jerry Garcia's "Tiger" guitar. I used this perfboard layout as a reference.


texts: How do relay contacts survive inrush current?

texts:
As I understand it inrush current is the current when the contact closes. Resistance is not minimum yet, and still inrush current can be several times the nominal current, like 80A on a 10A relay. How come that the inrush current doesn't weld the contacts?

edit
case in point: this relay can take 800A (!) inrush for 200\$\mu\$s


texts: Optical receiver output voltage higher than power supply

texts: The part is a optical receiver from Broadcom. It has TTL output, but specified with a maximum output-high voltage higher than the power supply. I wonder what's special structure internal may make it goes beyond the power supply. As known, it's not good to do this in digital design.


texts: How does the size of a reservoir capacitor affect battery life?

texts:
I have a circuit, powered by a 9V alkaline, where a solenoid is actuated via a MOSFET.  I have a large reservoir capacitor (4700uF electrolytic) on the high side of the solenoid.  I was wondering how changing the value of this capacitor will affect the battery life.  Is it the bigger the value cap the better the battery life?  For example, increasing the capacitor size from 4700uF to 6800uF should I expect a big increase in battery life?

Thanks everybody!


texts: Floating point representation- Double precision

texts:
The difference between 201 and next larger double precision number is 2^P.
If IEEE double precision format is used then the value of P is _________?
-- I know how number is stored using double precision, It is of 64 bits: 52 bits used for mantissa and 11 bits used for exponent and 1 bit used for sign. It uses excess 1023 code for biasing but i'm confused with this question. Please someone help me to visualize it.


texts: What is the purpose of the gate runner on a semiconductor die?

texts: With reference to the image of a FET die below, the gate pad is used to make connections from the die out to the device package.  But what is the purpose of the gate runner? Why does the gate connection need to run around the device like that? Is any electrical connection made to it?


texts: Generating simple alert tone MCU project

texts: A receiver part of my project should activate a light tor few seconds but they decided to add an alert tone which will be played on the PA sys of a building. I think input is 8 ohm imp PA. I was looking for an easy, fast way to implement a ability to generate an alert tone. I'd love to make DTMF tones and step them up in sequence (in volume) since they are easy on the ear. Nothing too complicated basically an alarm clock sounds would be nice.  I have my design done, and I have an Atmel AtMega, so I don't want to add anymore parts and like to use the Atmel to accomplish this. Any guides on this would be a great help. I've never generated a tone directly out of the MCU.


texts: How does a negative trigger close the latch in triac?

texts:
When anode to cathode voltage is positive, I get that the left latch will be closed if positive voltage is applied at gate.

However when anode to cathode voltage is negative, I don't get how the right latch will be closed if negative voltage is applied at the gate.

I feel positive voltage at gate must close the latch in second case too. Because no matter how the diode is oriented positive at P side forward biases a diode. But my textbook says the opposite.  Highly appreciate any help. Thanks!


texts: 6 LEAD 3 phase motor rated at 220V on 415V supply

texts:
So my PM bought a 3 phase japanese motor
(second hand) that is rated at 220V. Our system voltage is at 415V. Can i run the motor in wye configuration at 415V supply? If so, would it run without problems? (lower lifespan expected)
Driven by a VFD that runs on 380-415V.
Your help would be highly appreciated.
Seems like i can't get the VFD to output 220.


texts: How to reduce the effect of electric lighter noise on Micro controller?

texts:
I am using a kind of electric lighter in my circuit in order to turn the fire on.

And also i have used some sensors that alert in danger by sending a signal to the MCU (ATmega 32) interrupt.
The lighter works with 220 V AC in its input so I used a relay to switch it on and off. Also I used emitter common transistor to make the relay controllable from MCU. Right before it I have used an optocoupler to separate the power supply. But when the lighter starts working, the interrupt program begin and this is my problem.

I have used many methods for example i placed small capacitors on Interrupt's pin, used sound insulation cover around MCU, covering the lighter, covering lighter wires, using ferrite bead (on the output of the power supply of MCU), using big capacitors. They helped me to reduce this noise But not enough to solve my problem. What should I do?
Maybe the lighter is too powerful!


texts:
I have started designing a 4 bit Arithmetic and logic unit.

The sample image is as follows:

The function Table:

My question is: Is it possible to design an 8 bit ALU having the same functionalities (as in Table ), by using exactly two 4 bit ALU’s (as if Figure ) and an ‘And’ gate.?


texts: What is the cause of voltage drop across a resistor?

texts: We always assign a voltage drop to a resistor when a current goes through it in a closed circuit. I was wondering if this voltage drop is due to dissipated heat from the resistor or is there another reason?


texts: Delta-Wye transformer differential protection during external line to line faults

texts: During these kind of line to line faults current flows in the faulted phases of the secondary and all phases of the primary as it is shown in the image. So now the currents in phase A are not equal to each other(even if you account for the transformation ratios of the power transformer and current transformers). How can a numerical differential relay figure out that this is an external fault and not trip? I could not find a discussion of this in Siemens, ABB, Schneider manuals.


texts: can't figure out why my micronucleus/V-USB setup doesn't work

texts:
I built a small attiny85-based board using vusb and essentially the schematic of the discontinued Sparkfun "AVR Stick" (at least on the usb/uC side; see https://www.sparkfun.com/datasheets/Widgets/AVR-Stick-v12.pdf).

Trying to run micronucleus , a V-USB based bootloader, on it, I used the following config changes from the included tiny85-default example (to accomodate for different pins):

#define USB_CFG_DMINUS_BIT      0
#define USB_CFG_DPLUS_BIT       2
#define USB_INTR_VECTOR         PCINT2_vect

as far as i (and the available documentation) can tell, this is the correct setup.

when I try to connect it to my PC via usb though, I get enumeration errors, and attaching a logic analyzer to its VCC (to trigger on plugging it in) and data lines, I see the following traffic:

VCC high
a few random broken packets as the uC spins up
a loop of:

SYNC PID_SETUP 0x00 0x00 CRC_OK EOP (handshake begin)
SYNC DATA0 0x80 0x06 0x00 0x01 0x00 0x00 0x40 0x00 CRC_OK EOP (no clue)
expecting either a SYNC ACK or SYNC NAK packet now, but nothing happens, except for
a few evenly spaced (and very slow, compared to the previous packets) keepalives, until it retries this loop a few times (with a few resets+vcc cycles from my kernel trying to un-break the stuck device)

the data lines going into idle state as my kernel gives up on it and decides to just deliver power

I attached a csv dump from my logic analyzer here.

If anyone has an idea what's going on here or how to fix it (or at least how to get more info on what's actually wrong), any help is greatly appreciated :)

EDIT: forgot to mention above, the logic analyzer is attached at the uC pins, not inline of the USB connection, so it's very likely a software problem since the electrical signals definitely reach the uC. a simple pin-toggling test program (with unchanged fuses) confirms the uC is running at the time.


texts: Bluetooth device spurious emissions test

texts:
I'm reading an outline of spurious emission test for Bluetooth devices which states that

  The Equipment Under Test (EUT), a Bluetooth module is switched to a test
   nullmode in which it generates the transmitter signal required for the test.

Does that mean all Bluetooth devices from toys to speakers need to implement a separate, specific test mode for the spurious emission test even if they incorporate a certified Bluetooth module? From my understanding, this test mode enables loop back mode which may not be pertinent to the actual normal operation of the device, ie most devices don't utilise loop back mode.

In fact, how is this test mode triggered in the test lab? Must the device itself need to be able to switch to test mode given a certain packet?


texts: How to solder USB-A female socket to PCB?

texts:
Sorry I have tried many google searches but can't find anything directly relevant.

A USB Type-A female socket, through-hole, right-angle PCB mount has small 45-degree bent pins for soldering the shield to PCB. What should be done with these pins? Should they be pushed through a hole and bent over on the other side? Why are they bent to start with?

From:
https://nz.element14.com/wurth-elektronik/61400416021/usb-2-0-type-a-receptacle-tht/dp/1642033?st=usb%20a%20socket


texts: In our product, we are using SIM800C for server communication. A few of our SIM800C are not getting ON immediately after power up. But after 15-20 seconds, the network status LED starts blinking and it gets connected to network and works properly. However initially it is not switching ON nor replying to the AT commands. There is not issue in the PCB design. If I change it for another SIM800C, it working properly. Only a few SIM800C are getting delayed startup. Even if i move the Delay start sim800c to new pcb also its getting delayed startup. even i tried powering up many times but still i have same issue.


texts: simple, energy efficient circuit to make single IR LED blink

texts:
I'm using a 850nm IR LED (spec sheet), and in order to extend my battery life, I'd like to make the LED blink (UF 1.9 V, IF 100 mA).

I found a couple of links 1, 2, 3 but they either a) require two LEDs that blink in alternation, or a bunch of resistors that will most probably just drain my battery even quicker (will they?).

Therefore my question:

What's the

most simple
energy efficient
smallest possible (ideally not bigger than the battery & LED)
ideally operated with 3V or less.

circuit to make an IR LED blink?

EDIT:

I'd like to blink the LED 10 to 30 times per second. But We can start with 2 to 5 times.
the LED should be on for 10ms (at least) or 100ms (at most). Depending on blinking frequency.
I'm trying to make the circuit as small as possible (size and complexity) cause I wanna use it for a tracking device.
I'm powering the LED with a 3V CR2032 battery and I was hoping I could extend the battery life by making the LED blink instead of having it on all the time.
I can currently run the IR LED with the CR2032 battery for 4 hours. Extending that time to 8 or maybe even 12 hours would be great.


texts: Level Translation Clarification (LVPECL and LVDS)

texts:
I am trying to understand something about level translation. I am sure I am probably misunderstanding something basic, so I'm hoping you can help me understand.
I am trying to convert a LVPECL signal to LVDS (from the search I have seen a lot of the opposites). I understand that for LVPECL high is from 3.3 to 2.4 and low is 1.6 to 0/GND while in LVDS, high is ~1.4 to ~2.5-3.3 and low is 1 to 0/GND.
I am looking at this https://ww1.microchip.com/downloads/en/DeviceDoc/Differential%20Clock.pdf (mainly page 6).
My confusion arises from the figure. I am assuming the LVPECL driver/triangle is just my device outputting the LVPECL signal and the LVDS receiver is my device that takes in a LVDS signal/where I want to input it. I assume Zo=50 is just the cable and the intrinsic impedance that connects the output to input. So my question is, if I want to convert LVPECL to LCDS, do I just need to add the other resisters and capacitors to ground and power supply? I don't think I've ever seen this and it sounds pretty jank/sketchy in my head which is probably where my confusion arises from.
Thanks in advance.


texts:
Just had a theoretical question. I'm reading a book on LTE, and I came across an introductory section that talks about using higher modulation with channel coding. I understand that usually using modulation schemes like 16 QAM and 64 QAM will require more Eb/No at the receiver end as compared to QPSK. But then they talk about the higher modulations being more efficient when combined with channel coding, that is, they require a lower Eb/No at the receiver as compared to QPSK. The example the books talks about is as follows:

"As an example, if a bandwidth utilization of close to 2 information bits per modulation symbol is required, QPSK modulation would allow for very limited channel coding (channel-coding rate close to 1). On the other hand, the use of 16QAM modulation would allow for a channel-coding rate of the order of one-half."

I'm confused about the second part of the statement. How do we get a channel-coding rate of one-half? Can anyone shed some light on this or perhaps point me to something I can read to get a better understanding?


texts: Having problems with a window comparator

texts:
I'm trying to set up a comparator circuit that only supplies voltage to a connected LED if the voltage provided falls within an expected range, but I'm having some problems.

For testing, I have it wired up as shown in the picture below with two 3V coin cell batteries powering the entire circuit. I'm using 1K resistors to set the Max input to 4V (Input3) and the min input to 2V (Input2).

I have the two comparators working alright (they send a high signal of 1V and low of 0.2V, which seems un-ideal, but I’m not sure if that is how they’re supposed to work – that’s why I have the diodes connected in ‘reverse’). I want to have one output, which gives a 3V high if both the comparators give output a high signal, and 0V low signal otherwise. I’d love it if I could manage this without using a separate AND gate (using one of the two free comparators on the LM339). Is there a simple way to do this?


texts: Electronic components that can pull a string around 5cm and then suddenly release it?

texts:
I have very basic electronics knowledge. I'm looking to build a very simple circuit that pulls on a string which will start a pendulum swing.
I was initially thinking using of a using linear solenoid to push against a taut string but the ones I see do not have enough travel. A motor could work by winding the string but then it would need to quickly reverse direction to give the pendulum enough momentum.
Do you guys know of any components which could achieve this task? Ideally components which could be made to be silent and cheap to buy.
Would be greatful for any ideas!


texts:
I am attempting to build a system which stays active when an RFID tag is present and then deactivates when it's removed.

RFID readers seem to have an output that fires once when the tag is in range and then doesn't run again until the tag is moved away then then rescanned.

My initial idea was to use a standard reader and then reset it forcing a new tag to come through each time. The ID-20 reader has a reset pin which I believe supports this.

I would prefer to use a cheaper reader for this project as I have quite a few to build so I am currently working with this device.

The cheaper reader doesn't have a reset pin so I was going to toggle the power to the reader when I wanted a new read. Sadly this didn't work as planned, this cheaper reader only seems to read when a tag is moving through the field.

Has anyone done anything like this before and can offer advice or would anyone know why the cheaper reader wouldn't work when the tag is static?


texts: Can 3-phase FOC control be done without current measurement?

texts:
Can a FOC control scheme be done using a rotary encoder to measure the position, speed and acceleration directly, or is measuring current necessary?

FOC is a motor control scheme as described in links below:
http://www.atmel.com/Images/doc32126.pdf
http://www.eetimes.com/document.asp?doc_id=1279321
Quote from the second link:

  Field Oriented Control is one of the methods used in variable frequency drives or variable speed drives to control the torque (and thus the speed) of three-phase AC electric motors by controlling the current.  With FOC, the torque and the flux can be controlled independently.  FOC provides faster dynamic response than is required for applications like washing machines. There is no torque ripple and smoother, accurate motor control can be achieved at low and high speeds using FOC.


texts:
I have 8 DC brushless motors that are connected parallel to a DC source.
According to the motor manufacture each motor powered with a 12V DC and need 11A.

How can I calculate the the current load of all 8 motors ?

Motor Spec:

Required Voltage: 11.1v
Suggested Battery Capacity: 1300mAh +
Suggested Prop: 10x4.7, 11x3.8 or 11x4.7
Max current draw: 13A (with 11x4.7 prop)
No Load Current: 1.2A

All 8 motors are working with 12v battery 5000mA with no problem.


texts: SMPS Input/Output ripple current and ripple voltage

texts:
I found a presentation regarding SMPS and found this slide.

I am not totally able to grasp the concept of the input and output ripple current.

In the above image I have the following questions :

I thought input capacitors are used only for providing a constant DC supply during power interruptions to the downstream circuit. In the first image, it is writter as "Add cap for filtering high peak currents". I dont understand how a capacitor can filter high peak currents. Please explain with an analogy.
Why do we need short traces at switching nodes and why do we need to keep the loop area small?

Please help me understand.


texts: I want to use famous 741 ic to amplify the voltage from a sensor which is in the range 0-50 mV to 0-5V but the problem is all the circuits I found on web use +/- supply but i want to use only 5V supply from arduino so no negative voltage. Which configuration i need to use for a gain of 100?  When input is 0, output should be zero when input is .1mV output be 10 mV...if 741 is not feasible, suggest alternate ICs with single supply that accept such low voltages


texts:
How can I calculate Rdis in this circuit.

The load connected to Vset in this sensor for -300mV biasing.

Here the complete circuit. The sensor need a -300mV bias voltage between sensing and reference pins.


texts: Given the power spectral density, how do I calculate the bandwidth and total power of \$X(t)\$?

texts:
Given the PSD (power spectral density), \$S_x(f)\$, of a signal, how do you calculate the bandwidth and total power of \$X(t)\$?
I think I have the bandwidth but how can I get the total power of \$X(t)\$ given \$S_x(f)\$?


texts: How can I separate 2 power sources so only one can flow at a time?

texts:
I am building a battery charger circuit that can recieve power from 2 sources. However I need to avoid both sources from supplying power at the same to prevent any electronics from being damaged.
So I need to find a way for only one source to run while both power supplies are connect.

For example:
If power supply 1 is flowing, power supply 2 can not or vice versa

The first power suppply is 1A 5V and the second is 2.1A 5V
vice versa.

How can I solve this in the smallest way possible as the size is very important?


texts: How to protect Relay's NC contact tip from wearing out?

texts:
I made a rev limiter by using a 5V SPDT relay on motorcycle between the CDI and ignition coil. The relay works fine. However, the NC contact tip wears out very fast.
I added a 1N4007 at NC and COM to protect the contact pin, but the voltage still passing through from NC to COM although the COM already switch to NO pin. So this method is not working.
Am thinking to add an RC snubber to the relay, but wondering whether it will have the same problem as above.
Should I replace the mechanical relay with an SSR instead?
This is the relay that I'm using now:

Edit:
This is my current schematic.


texts: Ways to visualize current return paths on a PCB board

texts:
Overview
I'm writing a paper on PCB layout, and included with the paper are some evaluation boards. Generally the boards demonstrate different layout concepts (bypass-caps, trace widths, controlled impedances). I want a board that can show current return paths at various frequencies.
Pictures below show an example of the board and the general current returns at low/high freq. What would be really useful is a way to see the current as frequency changes. Is there a good method to measure the current flowing along the plane? And by measure I mean just generally knowing where most of the current is flowing, there is no percent error spec. I have two thoughts, but am open to more.
Method 1:
Place small resistors (mΩ range) on the plane and have a current shunt amplifier measure current though them. Would have to cut up plane a bit but would give voltages that could be probed and observed
Method 2:
Pass a large current (>1Amp) through the board and measure heat on 2nd layer with a thermal camera. This would be a bit more expensive but I think it would give some nice looking results. I'd be a bit worried about the heat from the top layer propagating down but that could be mitigated with a thick trace or maybe even a wire folded down close to the board that emulates a trace.
Pictures and Inspiration
Idea comes from this tutorial (figure 10-12, also shown below). Those picture are simulated though.
https://www.maximintegrated.com/en/design/technical-documents/tutorials/5/5450.html


texts:
I have heard a lot (!) of misconceptions and anecdotal explanations for why 100w of tube amp is way louder than 100 of solid state (SS) amp.
Now, knowing that 100w is always 100w, why is a 100w tube amp indeed perceived as being a lot louder than a 100w SS amp? Using the same signal source and speakers, obviously.

Is it because of how they clip differently? Is it the different frequency response perhaps? Are they rated by the manufacturers under different conditions?

A scientific/technical explanation would welcome.


texts:
I'm writing a university paper about UART as part of my computer science education. I'm looking at different state diagrams of UART, somewhat puzzled that they are so different. I already asked some questions about it and I begun to understand the basics. My plan is to make a good state diagram about the UART I own: The avalon_altera_uart which is part of FPGA:s from Altera (I own the FPGA Altera DE2-115). That particular UART is desribed in page 68 of the manual. But there is no state diagram for that so I must learn how to make a state diagram for that and then I can model it in NuSMV and step through the states.

My question is about a detailed diagram I see on page 35 of this slideshow https://www.slideshare.net/AkshayShah57/usbbasedclosedloopdigitalcontrolsystem

I don't understand what all his variables are. Is the UART 16 bits? Does RxD mean received 16 bits? What does rsr mean? What does dcnt mean? What does b mean? Can I use the understanding of his UART diagram to make a state diagram of my UART (https://www.altera.com/en_US/pdfs/literature/ug/ug_embedded_ip.pdf#page=68) ?

I just begun to make some code in NuSMV to model it, the code is not right and some of it is "dummy code" but I use it to develop the model in NuSMV that should correspond to a state diagram of the altera_avalon_uart.

MODULE main
-- ACTIVITIES
-- 1. Fill in the smv definitions
-- 2. Then run this file
VAR
-- system outputs
    Bit1 : boolean; -- Boolean variable
    Bit2 : boolean;
    state : {s1, s2, s3, s4}; -- scalar variable
    -- the model has states: location, that equals to idle, start, top, data, paritybit and tsr
    location : {idle, start, stop, data, paritybit, tsr};
    load : 0 .. 1;
IVAR
-- system inputs
    input : boolean;

ASSIGN
    init (location) := idle;
    init (state) := s1;
    init (Bit1) := FALSE;
    init (Bit2) := FALSE;
    next (location) :=
        case
            (location = idle) & (load = 1) : start; -- if state is idle and load=1 then next state is start
            (location = start) : data; --if state is start then next state is data
            TRUE : location; -- if conditions fail, then do not change location
        esac;
    next (load) :=
        case
            (location = start) & load < 1 : load + 1;
            TRUE : load; -- otherwise, do not do anything to load
        esac;
    next (state) :=
        case
            state = s1 & input = TRUE : s2;
            state = s2 & input = FALSE : s3;
            state = s2 & input = TRUE : s4;
            state = s3 & input = FALSE : s1;
            state = s3 & input = TRUE : s2;
            state = s4 & input = FALSE : s3;
            TRUE : state; -- why?
        esac;
    next (Bit1) :=
        case
        -- To Do
            Bit1 = FALSE : Bit2;
            TRUE : Bit2;
        esac;
    next (Bit2) :=
        case
        -- To Do
            Bit2 = FALSE : Bit2;
            TRUE : Bit2;
        esac;

I have done the following diagram of UART that I think is not right, since it models the bits and the bits are not exactly the states.


texts: Will a filtered 250V IEC socket still work given 110V?

texts:
I have a very nice IEC socket I got at a swap meet a few years back:

http://www.mouser.com/ProductDetail/Schurter/43025001/?qs=%2fha2pyFadujsDnoxV1Y8VQWgys%252bCu2GOjmVWnETFUeE%3d

It has an integrated switch and filter, and I would like to incorporate it into my 3D printer build. However, according to the spec sheet (link), this socket is designed for 250V. I live in the USA, and our standard wall voltage is 110V.

My question is:
Will this socket still work for my application? If the filtering circuit isn't provided the full 250V, will it still produce a filtered 110V sine wave on the other side? If not, I'll need to go hunting for another socket/switch combo.


texts:
I am a beginner electronic student and I know this might sound a bit easy for most of you, but I would like to understand the role of the components used in this circuit - it's an LDR-Controlled DC Motor.

So, I know the basic things like the voltage divider between the LDR and the pot and the use of the diode, but I'd like to understand what's the role of the capacitor, the 10k resistor, the BC548 and the TIP32 in the circuit.


texts:
What CPUs use a skewed associative cache?

I see several people imply that, with roughly the same hardware, a skewed-associative cache often has better performance than a traditional set-associative cache. (a) (b)

Ideally I'd like to find a soft-core processor in VHDL or Verilog that uses a skewed associative cache -- haven't found one yet, but perhaps I'm not searching in the right places with the right keywords.
Details about a skewed associative cache in a mass-production hardwired CPUs I would also find interesting.


texts: How to make sure a clocked operation happens just once in Vhdl

texts:
title may be a bit confusing but what I try to do is to take data from ram/modify it and put that data back to the ram. I want all of this to happen just for the operation(Brightness/Contrast) time when I enable the system instead of happening over and over to the point where data becomes deformed. Here is the code. I want write_enable(which enables writing to ram) to stay at 1 just for the operation(in a window which I call cursor) time then go back to 0 even if enable is 1. This is some image processing and I change brightness and contrast of the image in a window I call cursor. This change must happen for all pixels inside cursor just once. I tried many things(complex control mechanism) but failed due to vivado's unused element removal issue.I am totally out of idea on how to do that. How can I construct such a control mechanism??? I put commends(from here/to here) to show where this problem takes place.

rst is input
clk and clk2 are different clock signals
done is signal
data_in_ram is ram input
output_of_operation is output of change of Brightness or contrast operation
data_rom is output of rom
PICTURE_WIDTH_HEIGHT is length of my square picture (250*250)
pos_x and pos_y are signals that denote pixel coordinates
cursor_pos_x and cursor_pos_y are upper-left coordinate of the window or cursor
length is length of the square window or cursor
clk is 25Mhz
clk2 is 50Mhz. this is chosen 50 due to ram's read latency(2 clock cycle)

The ram and rom below are constructed using block memory generator.

Reading_Writing_Resetting_Ram: process(clk2,clk,rst) is
begin

    if rst = '1' then
      done <= '0';
    elsif rising_edge(clk) then
        if done = '0' then
            if address_rom < conv_std_logic_vector((PICTURE_WIDTH_HEIGHT*PICTURE_WIDTH_HEIGHT),16) then
                write_enable <= '1';
                data_in_ram <= data_rom;
                address_ram <= address_rom;
                address_rom <= address_rom + 1;
            else
                address_rom <= (others => '0');
                write_enable <= '0';
                done <= '1';
            end if;
            -------------------------------------part above is for resetting ram
        else --if done = '1' --From here
            if ( pos_x >= cursor_pos_x ) and (pos_x < cursor_pos_x + length) and ( pos_y >= cursor_pos_y) and (pos_y < cursor_pos_y + length) then --if within cursor

                address_ram <=(conv_std_logic_vector((pos_x + pos_y*PICTURE_WIDTH_HEIGHT),16));
                data_in_ram <= output_of_operation;

                if enable = '1' then
                    write_enable <= '1';
                else
                    write_enable <= '0';
                end if; -- enable
            else --if out of cursor -- to here
                -------------------------- part below is for reading from ram
                write_enable <= '0';

                if (pos_x < PICTURE_WIDTH_HEIGHT) and (pos_y <PICTURE_WIDTH_HEIGHT) and (pos_x >= 0) and (pos_y >= 0) then -- if within picture

                    address_ram <=(conv_std_logic_vector((pos_x + pos_y*PICTURE_WIDTH_HEIGHT),16));

                end if;
            end if;
        end if;
    end if;
end process;

This code below is used for second condition for write_enable but vivado removes this components.

Adjusting_enable2: process(rst,clk,cursor_pos_x,cursor_pos_y,enable,cursor_mode,current_cursor_mode,c_cursor_pos_x,c_cursor_pos_y) is
begin
if (rst = '1') or (cursor_mode /= current_cursor_mode) or (c_cursor_pos_x /= cursor_pos_x) or (c_cursor_pos_y /= cursor_pos_y)  then

enable2 <= '1';
c_cursor_pos_x <= cursor_pos_x;
c_cursor_pos_y <= cursor_pos_y;
counter_for_enable2 <= 0;

elsif rising_edge(clk) then

if enable ='1' then

if counter_for_enable2 < PICTURE_WIDTH_HEIGHT*PICTURE_WIDTH_HEIGHT then

counter_for_enable2 <= counter_for_enable2 + 1;

else

enable2 <= '0';

end if;
end if;
end if;
end process;


texts: Sum 4 numbers, 1 bit each, with three full adders

texts:
My excercise is the following:

Make a circuit which sums 4 binary numbers, one bit each, with three full adders.

My solution was the following (sorry I can't draw here).
Let the numbers be a,b,c,d.

First FA:
Entries: a,b, '0' as carry in. (first addition, no need for carry in).

Second FA:
Entries: sum of a,b from first FA, c, carryIn: carry out from first FA.

Third FA:
Entries: sum of second FA, d, carryIn: carry out from second FA.

I would ask your kind help to let me know if my solution is correct. Furthermore, if you can suggest a better solution, please do.

Thank you.


texts: Will a purely inductive load damage my function generator?

texts:
Will an inductive load damage my function generator? Will the circuit I'm designing damage my function generator shown below.

I'm using this function generator which has an output impedance of 50 ohms: https://www.gsi-protek.com/9205a9205c


texts: How to build a USB charger circuit that can switch between the USB and the battery power automatically?

texts: I'm building a PCB that will have a circuit that recharges a Li-ion battery from the USB power. The board should also be able to be powered both when it is draining power from the battery and when it is being recharged from the USB port. I found a IC from Linear Technologies called LTC4055 which seems to do all that I need, except that the top output supply current is of only 500mA (I need at least 800mA). Someone has an idea of how to build such circuit?


texts: Reusing an 8 bit microprocessor? (86CH09NG)

texts: I salvaged some parts from a microwave and I am wondering if it is possible/ feasible to reuse the 8 bit microprocessor on it? I am also not sure if I found the proper datasheet for it? (link to datasheet)


texts:
Given below is a VCO circuit. Can anyone explain how the components work (especially the resistors and capacitors) and why the resistor and capacitor values are selected so. and what are the values to calculate gain KVCO=f1−f2V1−V2.  As little as I know this is a relaxation oscillator?

(This is not a homework question)


texts: Learning designing a Arduino pcb, doubt about USB traces

texts:
what consideration should I have for the USB section. How do correctly the usb traces? What means this curves?

This is my reference schematic and due board.

Thanks