texts: Pulldown to prevent floating input pins for multiplexer

texts:
I'm designing a multiplexer shield for Arduino, by which it will (hopefully be possible to read up to 64 analog inputs such as potentiometers etc.. Schematics of rev.0.1 can be found here.

I'm using a I/O expander to switch between the inputs of 4x 74HC4067's, all channeled to one of the Arduino's ADC pins. The guiding line for the design is that it will be modular - i.e. the user can connect blocks of 8 pots, sliders, or other resistive inputs to IDC headers. The board should also be easily adapted by advanced users for use with different number of connections in blocks.

When connecting a single 8-input block of resistors to half of a 4067's ports, the remaining ports remain floating. While the user is not supposed to read the inputs of these latter pins, I would prefer to have them tied down to ground.

Edit: I thought of adding a pulldown resistor to each of the 4067s' inputs, than use 50k pots on connected sub-modules. The Atmega328 datasheet says its ADC is optimized for 10k and lower, but a quick calculation gives 5V/51kOhm=0.1mA, so I think it shouldn't slow the ADC too much.

simulate this circuit – Schematic created using CircuitLab

Going through TI's app note I found the following equation:

I'm looking for a pulldown R value, so I exchanged V(t)=5, Vcc=0, and got (approximatley) R=1kOhm. (C_T=10pF,t=500ns).

So (finally) my questions are:

Is this the right way to calculate  the required R value?
This value is quite high, which means it will affect the reading from my inputs. Is there a better way?
I assume pulling the pins down may also help to keep the ICs from damage, is this true, and are there other benefits (or negatives) I'm missing?

Thanks!

UriSh


texts: EAGLE 9.4.1 How do I autoroute a range of signals?

texts:
I have a board with three 32 input analog multiplexers, along with more components, connected to a 96 way DIN connector. How do I manually tell the autorouter to select only the muxers signals? I tried "AUTO U1_S[1..32]" for the first muxer but apparently eagle bugs out and select only up to U1_S3, ignoring it is actually 32 instead of 3.

I tried to select them from the design manager but it doesn't seem to care at all an routes the whole board.

It is a bug or a feature and I'm doing it wrong? I know I can manually click all 96 wires but... I would have to do it every single time and that's not cool.

All three muxers follow the same naming schema, as U1_S1..U1_S32, U2_S1..U1_S32..., etc

Ignore the fact that the autorouter is evil, that it creates weird traces and so.. but routing a 96way 3 row DIN connector is quite tricky for me and the autorouter already does the 100% of the board, but I'd like to try "guiding" it selectively.

I'm learning how to do it on the go, so please be kind. Also I'm aware that this is not a DIL atmega board with headers. If I need to write down all 96 nets and copy and paste from notepad...that's ok too but if there's a more human friendly obscure way the better.

Thanks


texts: Why Power remains same in a Transformer?

texts:
If we have a step up transformer then the voltage at the secondary side will be more than the voltage at the primary side. Since we all know that

POWER = VOLTAGE * CURRENT

and because voltage at the secondary side is now more than the voltage at the primary side.

So will it not make the power at the secondary side more that the power at the primary side according to the relation P=VI ?

Then why is it said that power will remain same at the both side of the transformer when voltage on both sides is not same ?


texts: What is this component on a satellite TV STB?

texts:
can you please help identify this component and tell what is it for?

Component:

Component image

It is mounted on a satellite tv STB.


texts: Counter Circuit starts from wrong number in Logisim

texts:
I'm trying to design a synchronous counter using J-K, T and D flip flop. It should count as "1, 3, 0, 2, 7" and 1 respectively.

Everything works fine, i designed flip-flop tables and input-outputs etc. but it starts from 0 and goes like 2, 7, 1, 3 and 0 respectively. I'm trying to find out my error but i just couldn't realize the error.


texts:
I am really in a tough situation and need very serious elaborative help with this. Almost like spoon-feeding.

It's been days I've been trying to get my zero cross detector (and the triac dimmer) to work properly but nothing works fine. I am trying to get my circuit to work but all in vain whereas there is another product (which I opened to reverse engineer) that uses the same triac and almost similar components but with few changes and sill works. I'll explain both cases to you.

I am using an H11AA1 optocoupler with a 150k resistor to use AC voltage to generate interrupts on my ESP8266 (esp-12e) micro-controller (integrated wifi). The circuit is as in image

But the problems that I face a numerous -

A 1/4W resistor gets too hot and burns if any lesser value is used.
The interrupts are for the RISING edge as there will be spikes when there is zero cross. The interrupt durations are (in milliseconds) are like -- 10,9,0,0,1,9,10,0,0,0,10,0,0,10,9,9,1,0,0,1,1,10,....... and so on. WHY?!!? Why is it so jumpy? And the random values? I was suggested that the current on the AC side is less. But as I said lowering resistance burns it and increasing might spoil it more. Talk about paradox, huh?

Now about the product I was trying to reverse engineer -

Why that's a problem to me -

They are using a variant of the (almost) same opto-coupler, H11A1. And they use a "330k" smd resistor (x2 times higher) that's got to be 1/4W. Now obviously the 2 times higher resistance is the reason why it's not burning. But how's that giving enough current to generate the right interrupts?

Please help me here. With the current scenario there's pretty irregular flickering in the triac dimmer tested with incandescent light bulb. It's been days to understand why this is happening...

Big thanks in advance.. :)


texts:
I want to build an instrumentation amplifier using MC33079 quad op amp, in page 3 of the datasheet it specified min and max input offset voltage:

What causes the input offset voltage to increase?


texts: How to drop the voltage of a power supply?

texts:
I have a DC power supply which outputs 21V 2.2A.
I want to use it to charge a car battery so I need to get the voltage down to 14V.
I have a 3.9Ohm 100W resistor but am am I correct that that would draw around 5A.
What resistor should I use to drop the voltage to 14V?


texts: Video stream over RF and converting to Wifi

texts:
So, here is the scenario: I have to put a camera far away from my wifi internet hub and want to see the video on my cell phone. I know that I can put Wifi repeaters, but it's not a feasible solution.

I was thinking if it's possible to have a camera transmitting the video using RF (radio frequency) and then convert into wifi, so then I could build an app and see/record the video from my cell phone.

I came to this idea after seeing Drones transmitting videos over Radio Frequency, but couldn't find anything on the internet.

Any suggestions? Thank you!


texts: How to light an LED when a voltage hits a certain point

texts: Lets say I need an LED to indicate when a DC voltage reaches 5 volts or more. I don't want the LED to be dim when it is at 4.5 or anything. I just want it to be full bright at 5, 0 bright at anything below 5. Is there a way I can do this with discrete components (no IC's, just resistors, capacitors, transistors etc.)? I do not require the input has the same power source as the meter.


texts:
I am trying to detect load resistance changes.

simulate this circuit – Schematic created using CircuitLab

I need to monitor R load resistance (glow plug).

PWM duty cycle (max) varies from 100% when V1 is 1.2V to 3.7% (8V)

I need to keep the temperature of the glow plug constant. The actual resistance of the glow plug is unknown (0.2 to 0.3R when cold). On the start-up I measure the voltage of the power supply - and power the glow accordingly (glow plus are 1.2V - for higher voltages the PWM duty cycle is k  = (V1)^2/(1.2)^2) ). When the engine is running I need to keep the glow temperature constant. So I need to detect changes in glow plug resistance - if it goes down (glow is getting colder) I need to increase the k, when it goes up (glow is getting warmer) I need to reduce the k.

Users can use any battery packs up to 8V.

The problem is that those changes are extremely low. For the particular V1 it quite easy to create the circuit which amplifies them (I was experimenting with the low pass filter and differential amplifier).

simulate this circuit

But I can't find any way to make it universal for the different V1.

I don't need to measure the actual resistance - I just need to detect the change of the resistance (if is going down I need to increase the duty cycle and vice versa)


texts: Why does capacitor charge slowly but discharge quickly?

texts:
I've designed this circuit using Multism 10.1 :

This circuit is part of clock generator for 8088 uP:

Why does the wave of ch1 of Oscilloscope which represent the voltage across the capacitor take this form?

What is the relationship between that and the delay that is caused by the capacitor? Click here


texts: How to estimate chip area from verilog design

texts:
I can synthesis the verilog design in Xilinx Vivado (Webpack) and get the LUT/FF usage from the synthesis report.
However, I'd like to estimate the chip area (in mm2) under certain ASIC (not FPGA) spec (for example in 22nm process).

Some articles claim that they got the area with Synopsys Design Compiler, which I cannot access to.

So are there any tools that I can use to estimate chip area from (synthesized) verilog design?

Update:

After some research, i tried qflow 1.1 with osu035 standard cell library for the following verilog code:

module test(
    input a,
    input b,
    output c
);

assign c = a + b;

endmodule

After qflow synthesize place, synth.log gives following area data:

----------------------------
Total stdcells     :4
Total cell width   :2.08e+03
Total cell height  :8.00e+03
Total cell area    :4.16e+06
Total core area    :4.16e+06
Average cell height:2.00e+03

But I have no idea which is the unit of the result.
The osu035_stdcells.lef contains following lines:

UNITS
  DATABASE MICRONS 1000 ;
END UNITS

Therefore, my best guess is the chip area is 4.16e+06/1000/1000=4.16 micron^2 or 4.16e-6 mm2. It that right?


texts: What is the simplest circuit to rotate TV Picture 90 degrees?

texts:
I have an old CRT TV (it is not a digital TV) from the 1980s and it has RF input only. Consider  a circuit that comes between the video signal source and RF input.  What is the simplest circuit that will rotate the image 90 degrees clockwise? What is the simplest circuit that will rotate 180 and 270 degrees clockwise? It is a standard UK TV (so it uses PAL).
Update: Given the answer and comment below.
So I do not want to physically move the TV (either manually or automatically ) to rotate the picture. I do not want to open the TV and modify the internals or, or open the TV and add to the internals to rotate the picture.


texts:
I'm in the process of making my own adaptation of the classic State Variable Filter (SVF) in the analog domain. Reading up on this article.

I discovered that they use superposition to get the equation of the High-pass output voltage. And then by integrating two times bandpass, and low-pass output voltages are derived. The latter part I understand. The former, however, I do not.

Superposition, as I've learned it is done by shorting all independent voltage sources and replacing all independent current sources by open circuits. But in this case they seem to have replaced all voltage sources by open circuits?!

I can do all this with nodal analysis, no problem. But superposition seems so much faster to me.. and better for my understanding.

Is there anyone out there who can explain this? It seems that all the articles I've read about SVF this use superposition in the same manner.


texts:
With regards to Ethernet frames, the typical maximum size is 1500 bytes. Jumbo frames brought this up to 9000 bytes, and there was even some Super Jumbo Frames of sizes larger than that.

What factors are taken into account when determining these numbers? Is it simple math or is trial and error required to create a table of values then the equations as development of a protocol continues?


texts:
Is it OK to use an asynchronous counter for DAC input? If I understand it correctly, the output pins on the counter do not change simultaneously with the clock? Does the latency for every higher bit adds up? In other words, going from 0 to 1 takes the same time as going from let's say 999 to 1000?

My system is 8 bit, but I need to create a sawtooth-looking rapm of 10bit increments. Instead of using two ports, I want to clock an external counter using only one bit. The counter, in turn, will advance every clock cycle, and provide the DAC with 1LSB higher input.

The word asynchronous worries me because if bits have different delays, the transition between powers of 2 can have some intermediate values. For example, going from 7 to 8 would look like 0111 -> 1000. If the bits do not flip simultaneously, the transition could look like this, for example: 0111 -> 0110 -> 01010 -> 1000. Is this how it works? The transitions might have some intermediate/indeterminate state?


texts: Surface-Mount Prototyping (AXL 335 & SFH 7050)

texts:
I'm working on a senior project and I'm having some trouble prototyping with surface mount components. I know you can find SMT adapters out there for most SMT chips and components, but I've been having some trouble finding adequate ones. Additionally, I'm new to using surface mount technology to begin with so I don't know if I'm even looking for the right things.

Here are datasheets to the two components:

http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL335.pdf

http://www.osram-os.com/Graphics/XPic7/00187722_0.pdf/SFH%207050,%20Lead%20(Pb)%20Free%20Product%20-%20RoHS%20Compliant.pdf

Any help would be appreciated!

Thanks in advance.


texts: Can i connect Power source (like usb charger) parallel connection with power bank output for keep Uninterruptible power supply (UPS)

texts:
I have a question about uninterruptible power supply (do it yourself).

I have a simple power bank and relay (or light) i want that my relay will be always on even the power adapter are disconnected.

The answer to connect relay from power bank only is unsuitable for. i need to use both power supplies (battery charger and power bank).


texts: Why I am getting Unexpected EOF? What's wrong?

texts:
I am learning VHDL and I am trying to do a simple Generic MUX. It is my code:

GenericMUX.vhd

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

-- Uncomment the following library declaration if using
-- arithmetic functions with Signed or Unsigned values
use IEEE.NUMERIC_STD.ALL;

-- Uncomment the following library declaration if instantiating
-- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;

entity GenericMUX is
     -- n: siendo 2**n la cantidad de entradas del MUX
     generic (n : integer);
    Port ( input     : in   STD_LOGIC_VECTOR(2**n downto 0);
              sel        : in   STD_LOGIC_VECTOR(n downto 0);
           MUX_OUT : out  STD_LOGIC);
end GenericMUX;

architecture Behavioral of GenericMUX is
begin
    MUX_OUT <= input(to_integer(unsigned(sel)));
end Behavioral;

MUX.vhd

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

-- Uncomment the following library declaration if using
-- arithmetic functions with Signed or Unsigned values
--use IEEE.NUMERIC_STD.ALL;

-- Uncomment the following library declaration if instantiating
-- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;

entity MUX is
    generic (n : integer := 3);
    Port ( input     : in   STD_LOGIC_VECTOR(2**n downto 0);
              sel        : in   STD_LOGIC_VECTOR(n downto 0);
           MUX_OUT : out  STD_LOGIC);
end MUX;

architecture Behavioral of MUX is

    component GenericMUX is
        -- n: siendo 2**n la cantidad de entradas del MUX
        generic (n : integer);
        Port ( input     : in   STD_LOGIC_VECTOR(2**n downto 0);
                 sel         : in   STD_LOGIC_VECTOR(n downto 0);
                 MUX_OUT  : out  STD_LOGIC);
    end component;

begin

    x1 : GenericMUX generic map (n) port map (input, sel, MUX_OUT);

end Behavioral

With Xilinx ISE 14.5 I get this error on MUX.vhd:

  ERROR:HDLCompiler:849 - "C:/Documents and
  Settings/Owner/Desktop/Xilinx FPGA/GenericMUX/MUX.vhd" Line 53:
  Unexpected EOF.

Line 53 is end Behavioral. Tried cleaning the project, creating a new one but I don't know what is wrong. Maybe some of my code generates this wrong error message.


texts: Do Duracell AAA batteries have internal short circuit detection?

texts:
I was shorting a Duracell AAA battery in a SAFE area with proper precautions. After 2 minutes I disconnected the circuit and measured the voltage, it dropped from 2.8V to 2.6V and the battery was hot. When I reconnected the circuit for another 2 minutes the voltage didn't decrease and the battery wasn't hot. I tried a few more times (after waiting 30 minutes) and the same pattern occurred: the battery drained a bit, but after some time it seemed as if the current stopped during a short. I used the battery to power up a led, it still works.

So I'm wondering if there are internal short circuit protections. If so what are they and can I get a few references?


texts: Does a dashed line mean "when energized"?

texts:
I'm having a hard time understanding this circuit diagram:

I'm interested in the following component sates, and how they affect power distribution:

the breakers:

the buses:

the AVIO MSTR switch:

I'm not well-versed in schematics, but I'm under the impression, that the dotted vertical line means "when energized"?

Does that mean the Avionic Buses cannot be powered unless the MASTER CB is popped?

This is my best guess on deciding whether the avionic buses receive power:


texts: Are black ash particles and holes on a cleaning sponge normal?

texts:
I've read in numerous places that an ordinary wet dish sponge can be used for cleaning the solder iron tip. I've taken a photo of what the sponge looked like after I cleaned by solder iron tip and shown it below.

The tip burns the sponge, small amount of smoke comes out and tiny black ashes can be seen on the sponge. Is this normal, or am I using the wrong sponge/wrongly?

I'm sure nobody cares about the sponge, I just want to keep my solder iron tip clean properly without damaging it.


texts: How does USB port on a power strip detect the optimal current output?

texts:
I am looking to buy a power strip with USB ports and came across this one online.
The description says "Top-notch USB smart charging technology which can detect and deliver optimal current output up to 2.4A per port." So when I charge my iPhone 6s which requires input current of 1A, the USB port will deliver exactly 1A?


texts: op-amp circuit to transform input signal

texts:
In this typical op amp circuit, how would I go about calculating the value of each component if I want to simply transform the input voltage range into another voltage range, e.g. when input voltage vary between -5mV and 20mV, I want the output to vary from 0V to 5V, at a given frequency.

Edit:
 Hmmm ... may be the circuit above is not suitable to do the transformation. If that is the case, what would be a good one for that?


texts: If I fully charge a 1.5V capacitor from 1.5V battery, how long can it keep the charge? If I connect it to 1.5V bulb would it lose that charge instantly? If yes why? Where would it go?


texts: How does the PWM from MCU get translated into a output voltage as in Power Electronics

texts:
Background: I am preparing for a full-time employment starting in May. I am coming from a computer engineering background so I only have some working knowledge regarding EE. The job duty is Firmware Engineer - I will be mostly dealing with writing firmware on a micro-controller for a switching-mode power supply board.

My question is: in digital power electronic, how does the PWM generated by the MCU get translated into a output voltage? By looking at the image below, I understand how the transformer, rectifier, and filter works. What I want to know is: what's going on with the waveform between the regulator and the load such that the output voltage becomes so smooth without noise, i.e. how the input waveform of the regulator get transformed into a straight line. Please explain in detail how the PWM, MOSFET, output Inductor, and output Capacitor are involved in this process.

I have done quite a lot of researches online learning power electronics by myself. However, I am experiencing a huge gap in between the digital world and the analog world (as a computer engineer, I only have experience with digital circuit). By looking at the picture of a digital power regulator below, I know that the MCU is responsible for generating a PWM to switch On and Off of a power MOSFET switch - depending on the difference between a reference voltage and a feedback voltage, the On and Off time varies to regulate the output voltage.

My analog knowledge is quite limited, what I understand so far is:

The PWM is providing a gate voltage above or below the threshold voltage of the MOSFET
The input voltage is supplying the drain of MOSFET, and the source of MOSFET is connected with a inductor and a capacitor for some "filtering purpose".
The inductor can lag response in current change where the capacitor can drag voltage.

But I must have missed something here. I have been struggling with seeing the whole picture of all these analog components working together to form a complete working regulator.

And, why there are two MOSFET instead of one?

Please help me out here.


texts: How are RC brushless motors able to handle very high current draws?

texts:
I've seen some specifications of RC brushless motors and ESC with very high current ratings from small motors having 16A draw to ones with 60 to 70A current draw. The specs also says peak current draws unto 200A are possible on certain motors.

What I'm curious is how can such small motors handle such high currents without damaging itself?

I've seen car starter motors draw hundreds of Amps, but they run only for few seconds and are big enough to dissipate the heat.


texts: Minimum Viable VNA N-to-N Test Cable for 2480MHZ

texts:
Can I get away with a $60 dollar N-to-N 1 meter cable from a reputable vendor for use in the scenario below? I have limited practical experience with a new VNA that just has an N connector output and in the past I have gotten the plane of calibration right up to the connector that attaches to the DUT.
Here is the scenario

looking for an antenna match S11 around 2500 MHZ, widest bandwidth 80MHz at 2480MHZ
Rhode and Schwarz 0-6GHZ open through load calibrator is not assigned any coefficients by Rhode & Schwarz
calibration plane is at end of 1 meter N-to-N cable, after which port extension will have to compensate for an N-to-UFL adapter in series with 4 inch UFL to UFL cable.
able to provide good short and open at DUT instead of estimating Td for port extension
N-to-N cable will be taped so it doesn't flex after calibration.
Not really planning on using a torque wrench


texts: My RTL viewer replaces NAND gates with AND gates with the inversion bubbles

texts:
I want it to show this MUX only with 3 NAND gates and an Inverter.
so, I specified NAND gate in the verilog HDL code, but it keeps replacing it with AND gates with inversion bubbles without having a single NAND gate. I want to fix this problem. I have to get NAND gates out of it. please let me know if you have any idea.


texts:
Following up on this question I redesigned my circuit with the suggestions from the comments (see comments from @Andy_aka). I want to drive the output of the opamp between 0-24V with an Vin = 0-10V. I also need to draw currents arround 50mA. At low input voltages the power consumption of the opamp would probably damage the device. With a voltage follower I want to draw the current directly from my power source. I found some circuits on the internet and tried implementing them into my design

The voltages seem to be correct for the base and the load (R3). The current from the base is still higher than the current on the load. Should the main draw not come directly from the power source and not the output from the opamp?

UPDATE: I switched the direction of the transistor per @James suggestion and the current in the base is greatly reduced, where the Emitter (load) side draws the current from the collector. I also redraw the result window


texts: How does using Flip Flops between transmission links increase the maximum clock speed?

texts:
I am learning about things such as propagation delay and Transmission delays. About how they limit the maximum Clock speed in a given system (where all the chips use the same clock line).

I can't post images as yet but I'll try my best:

Initial circuit:

invClock->MicroProcessor(A) -- (Transmission line with delay) -- Microprocessor(B)

Improved circuit which somehow increases maximum allowable clock frequency:

invClock->Microproccessor(A) -- FF -- (Transmission line w/ delay) -- invClock->FF -- Microprocessor (B)

The clock is also transmitted in an indentical transmission line, with the same delay.

How does this work?

simulate this circuit – Schematic created using CircuitLab


texts:
we are trying to build the K&J Magnetics Seismometer in my physics class and we are having trouble getting the LT1677. It's not available at the moment. What can we substitute in place of the LT1677 in the following circuit?

K&J Magnetics Seismometer


texts:
Let's say you unassert an asynchronous reset signal to a flip flop after you need to to meet setup timing but before the positive edge of the clock. You're in trouble right?

Now let's say you've got a chip full of thousands and thousands of flip flops, all asynchronously reset from the same signal. You unassert it right before the positive clock edge just by chance. Some interconnect delays are longer than others so when you deassert it, it'll reach one flop on time to clock in the D input but won't make it to another one on time. The whole point of the reset was to put the circuit in a known state, which it is while the reset is asserted but just due to bad luck parts of your circuit are off to the races where others are either waiting for the next cycle or went metastable.

What is commonly done to avoid this?


texts: PIR motion sensor connected to Arduino sometimes does not detect a repeatable trigger

texts:
I have connected the PIR motion sensor HC-SR501 to an Arduino Uno and its jumper settings is set to H and GND. (This is not a physical jumper, but a small link that connects both H and GND.)
It detects motion, but sometimes does not notice or retrigger if I am still standing in front of it.
Most times I have to wave my hand to indicate that I am still in front of it.
My test case is

After 2 or 3 seconds of being in front of it, and if I move my hands it should continue to stay in "motion detected" mode.
Even if I don't move, and the fact that I am standing in front of it - it should detect the body heat and stay in "motion detected" mode, as this is an infrared detector.

This behavior works most times, but three out of 10 times it stops detecting my presence and when I wave my hand, it takes the "default" sleep mode of 3 more seconds and then detects the movement.
The delay potentiometer is set to minimum. The distance sensitivity potentiometer is not a problem as I have set it to 3 feet (i.e the minimum) and don't see a problem there.
My problem is that it does not sense my "continued" presence to stay in "motion sensed" mode.
I have connected the motion sensor to an Arduino Uno and doing a digitalRead(Pin5) continuously in a loop every 50ms.
Appreciate if someone could answer and tell why this could be happening.
Just to note: The pins on the motion sensor VCC is connected to 5V of Arduino, GND of the motion sensor to GND on the Arduino and the digital output of the motion sensor to pin 5 of the Arduino.
I have placed the motion sensor at 90 degrees to me standing, does it have to be positioned any other way?
I cleaned the dome assuming there was some clog/dust - this did not help.
Any inputs would be appreciated.


texts: What is this symbol with designator T ? Looks like two pads pressed really close together

texts:
Are T1 and T2 relays?

This picture is grabbed from the datasheet of this component (high current power switch)

http://www.infineon.com/dgdl/Infineon-BTS555-DS-v01_00-en.pdf?fileId=db3a30432ba3fa6f012bd3dfdd0b3b65


texts: Which has less energy loss - AC step up/step down transformers or DC to DC step up/down converters?

texts:
In the EE field, AC transformers are constantly talked about. However, I don't hear much of DC to DC converter modules, even though DC is widely used today, mostly in smaller electronics.

Both of these perform similar operations by converting to a higher or lower voltage, but I am wondering which is better in terms of least amount of energy lost? I would assume that if transformers are not as efficient as these DC converters then AC would be rectified and then converted to higher voltage.


texts: Electrical apliances overheating when receiving LESS voltage

texts:
I've been wondering for a while now, why do some electrical appliances overheat and burn out when you lower their incoming voltage? Shouldn't the less voltage mean they receive less current, and less current should mean less heat?

For example, I have a LED lamp, which when run through a dimmer burns out its LEDs.


texts:
I want to press a key on my keyboard, for example "a" and a device should take the scan code of the button I pressed and transform it to something else: e.g. "b" or the scan code of b. What device can do such things? I need to be able to program it myself.
To clarify: I want to connect the device between the keyboard and the computer. I do not need a software inside the computer. I need it before the data arrives the computer.
I've already searched for keyboard encoders/emulators, but since I have already keyboard input, they can't help me.


texts: How to switch a MOSFET to drive a 5v relay from Raspberry pi?

texts:
I've been trying to power my 5v relay through a MOSFET but I can't seem to get it to work. I'm using a IRLI540N with the gate to GPIO 24 that goes high when I click the pushbutton (that much does work, I checked with some leds before) drain is to 5v and source is to one of the coils of the relay.

I tried the rest of the circuit manually switching the relay on with 5v power and it does work (the solenoid pulls, which is all I want to be able to do via code), I just really don't know how to switch it logically with this or any other sort of transistor.

Is there any way to switch it on with logic with the mosfet or through any other type of switching that doesn't involve a relay board module? (It would solve my problem, but I wasn't able to get one of those).


texts: Biasing an inverting Op-Amp using a voltage regulator

texts:
When biasing an inverting op-amp input using a voltage regulator (say, L7805), at the non-inverting pin, can we use the same regulator to power other ICs or should we only use it on the op-amp?
Also, in the case of an inverting amplifier, does the op-amp needs an input resistor at the non-inverting pin or can directly connect the regulator output and the op-amp?
Thanks in advance.


texts:
I am trying to convert the mechanical speedo in my car to run from the vehicle speed sensor that's fitted to the gearbox. I need a method to covert the pulses from the sensor (0 to +5v) to drive a 12v motor that will drive the speedo.
I've calculated that the VSS outputs 7Hz at 10MPH linearly up to 87HZ at 120MPH.
From this, the speedo requires a rotational input from the motor of 167RPM at 10MPH, linearly up to 2000RPM at 120MPH

I've looked at frequency to voltage converters and frequency to PWM converters but am unsure of the best way to do this. Ideally the motor should be accurately controlled so was erring towards a PWM output.

Can someone point me in the right direction? A simple circuit with some adjustability so it can be calibrated.

Apologies if this is a little short on info, I'm a newbie at this!

Thanks in advance :)


texts: Why would someone use an amplitude modulation ratio lower than one in a power inverter?

texts:
We had a test the other day, and there was this question:

  What is the minimum DC voltage required to drive a PWM, half-bridge, three-phase, power inverter to 4160 Vrms? It should be possible to vary the output 5% (up and down).

No one was completely sure on the answer; after all we also had to calculate the THD% from a table that only provided values for Vllh/Vd for even values of ma up to 1.0.

We believe it had something to do with changing the amplitude modulation ratio of the inverter but am not sure it was the best method. After all, the minimum is obtained for ma=1.0 (0.612 in this case as it was tri-phase), but how to make sure it varies 5% up, considering that over ma=1 it enters overmodulation?


texts: What is the difference between "Collector-Emitter" and "Base-Emitter" Saturation Voltage?

texts: As you can see on the datasheet below for the 2n2222a NPN transistor, the "Collector-Emitter Saturation Voltage" and "Base-Emitter Saturation Voltage" are defined respectively as 0.3 to 1.0 and 1.2 to 2.0. I believe I understand transistor saturation, but whats the difference between Collector-Emitter Saturation and Base-Emitter Saturation?


texts: How to read/generate phase-shift-keying (PSK)

texts:
I'm trying to reverse engineer a piece of electronics that seems to be using ~1Mhz differential phase shift keying to send a signal over a 2-wire line that's also used for low-voltage power.

So newbie question here, but how do I both encode/decode a PSK signal?  In terms of do I need to build a custom circuit to do it (I've found diagrams of such)?  Or are there cheap/small chips that will do this for me?  I ultimately need a micro-controller both reading and sending the signal.


texts: Given metal dimensions and material, is it possible to determine the maximum current that the structure can handle? [semiconductor processing]

texts:
I have a linewidth structure that has very low resistance. I want to know the maximum current that this structure can handle.

Since the resistance of the metal is so low, it's hard to measure the voltage drop. We can't change the size of the structure (as it's on all our masks and we're also limited in real estate) and we can't increase the voltage resolution of our tester (without sacrificing capacity or spending money).

So the only solution that I can think of is to increase the test current.

I've been searching for an equation or series of equations that will tell me at what current the structure will break (like a fuse). I'm sure that, given the structure dimensions (LWH) and the material parameters (resistivity, thermal conductance, etc), this or other similar equation exists. However, I can't seem to figure it out...

And then, to make things more complicated, I'm pulsing this current with a pulse width <= 100ms. It's normally only a single pulse, so a duty cycle doesn't make much sense.

Thanks,


texts: Can I replace polyester capacitor by ceramic in audio circuits?

texts: I'm redesigning an amplifier circuit. I'm using the TEA2025B. In the circuit there are some polyester capacitors, I would like to know if there are problems in replacing these polyester capacitors with ceramic capacitors. I have found ceramic capacitors with capacitance and voltage equal to the capacitors of polyester, but I do not know if it is correct to change.


texts:
What is the smallest cheap AC (110v) to DC convertor available for Arduino.  I want this to be embeddable in a box along with Arduino without taking more space.

Thanks in advance


texts: Formula seems to be wrong into a PFC application note

texts:
Here is the formula that I found into the following application note:

https://www.infineon.com/dgdl/an-1166.pdf?fileId=5546d462533600a40153559aabdf1128

The formula seems to be fault? Am I wrong?

Does it should be:

$$Iin=\frac{Pin}{\sqrt2*Vinrms}$$

It may be too late for my brain...

Thank you very much!


texts: Understanding voltage drop in control cables

texts:
I recently worked on a project that involved a 300 feet cable run from one part of a building to another at our plant. Its a simple 120V circuit that originates in a control panel, travels 150 feet to the NO contacts of a temperature controller, and back to the input card of a PLC inside the control panel...for a total of 300 feet. All the circuit is doing is detecting if the temperature has dropped below the setpoint which in turn turns the heater on.

Now as to why there is no remote I/O rack located near the temp controller is a story for another day. I am fully aware that this is not a well designed system but this is what we have for now.

First thing I encountered in my design was sizing the cable. I have designed power circuits in the past and figuring out voltage drop in power circuits is fairly straight forward as you know the power rating of the load and can easily calculate the current for a 3-phase 480V system.

Not so straight forward for control circuits apparently, because I am not sure what my load is (is it the I/O card?) and how much current it's pulling. Since I don't know the current flowing through the cable, I can't figure out the voltage drop. Even if I were to ignore voltage drop for a second, how could I size the conductor without knowing the current.

Based on an experienced colleague's suggestion, I ended up using 16AWG. But I'd like to know the specifics. Please advise.


texts: Best practices on splitting 12 V 20 amp supply into 5 devices?

texts:
I am running a 48 V to 12 V converter rated for up to 60 A on my custom pedicab setup. I'm fairly new at all things electrical and want to get this right.

I have five different devices that hopefully will not pull more than 20 A at a time from that 12 V supply. I will be running an audio amp (rated up to 15 A but I doubt it'll ever get that high), a 16 ft LED light strip (6 A), a set of fairy lights (1 A?), the front headlight and back lights that come installed on the bike (3 A?), and I also thought about adding a 12 V to 5 V USB supply to power my phone. I need to split that 12 V supply into all these devices.

Is this just a matter of using the proper gauge wire off the 12 V supply and then crimping 5 wires onto it? All the splitters I see on Amazon are barrel connectors for CC-TV rated for a total of 5 A. If I am going to actually buy a splitter, I need to buy it in person tomorrow? What sort of store sells such a thing and what is it I would need?

Thank you in advance, for any and all help!


texts: What is the output specification of an audio jack?

texts:
I am currently building an audio amplifier. The goal is to connect the amplifier to a audio jack and the other end to a (4 ohm) speaker. I want to know the specifications of the output power (including voltages and amps) of the audio jack.

I already connected the output the oscilloscope, but got different result based on different devices (my PC was giving 1.5 volts while the phone was giving "only" 1 volt). That gives the suggestion that there is a space in what could still be as accepted on the output of the jack.

P.S. I was kind of struggling if this question is really "electrical engineering" or something else. Please don't downvote, but let me know and I will remove it here and put in whatever else is better suited.


texts:
Here is my dark sensor circuit (below). However, my output current is very low. I get a maximum of 150mA to drive my strip LED. But I require atleast 450mA of output current.

I have tried many combinations. Tried emitter follower / tried replacing it with a N channel mosfet with not much improvements.

What can I do to achieve the desired 450mA?

I dont want to use a 3V relay in order to do this. Neither a solid state relay or a reed relay. Nor an optocoupler (low current). Any other alternate ways to do this?


texts: TWI/I2C Protocol with HMC5883L Magnetometer with ATMEGA256RFR2 XPLAINED PRO (megaavr)

texts:
Im trying to read Data Output Registers of X,Y,Z

So far I've been able to:

Send a START - flag 0x08 = START condition transmitted.
Send 0x3C - flag 0x18 = SLA+W transmitted, ACK received.
//For configuring HMC5883L Control Register A & B
Send 0x02 data byte - flag 0x28 = Data byte transmitted, ACK received.
Send 0x00 data byte - flag 0x28 = Data byte transmitted, Ack Received.
Send a Repeat Start - flag 0x10 = Repeat Start condition transmitted.
Send 0x3D - flag 0x40 = SLA+R transmitted, ACK received.

Start > SLA+W > Configure Control Register A & B > Repeat Start > SLA+R > ??

I'm stuck on what to do after sending a SLA+R, I've tried sending a 0x03 (MSB register for Output X). I keep getting a repeated fixed value like (0,10,10,18 - repeat).

My main question would be how do I correctly read the memory address of the slave at 0x03 followed by 0x04, 0x05, 0x06, 0x07, 0x08 successfully?

In the data sheet it is mentioned:

  When one or more of the output registers are read, new data cannot be
  placed in any of the output data registers until all six data output
  registers are read.

  To minimize the communication between the master and this device, the
  address pointer updated automatically without master intervention. The
  register pointer will be incremented by 1 automatically after the
  current register has been read successfully.

  The address pointer value itself cannot be read via the I2C bus. Any
  attempt to read an invalid address location returns 0’s, and any write
  to an invalid address location or an undefined bit within a valid
  address location is ignored by this device.

  To move the address pointer to a random register location, first issue
  a “write” to that register location with no data byte following the
  commend. For example, to move the address pointer to register 10, send
  0x3C 0x0A.

Any help would be appreciated, thanks in advance!


texts: How to measure power dissipation through each component in PCB board?

texts:
I have designed an RF based PCB board and for testing purpose I would like to measure the power dissipation through each component.

Someone suggested, by measuring the temperature of each component one can get the power dissipation. Is it a reliable solution ? Are there any other ways to measure that?


texts: Can a DC CC power supply be used for current limiting in a circuit with a battery in series

texts:
In circuit #1 I showed typical adjustable power supply usage it can limit voltage and current, all good.
It got me thinking. Let's say due to some reasons I can't replace battery with a power supply but I can connect it in series like showed in circuit #2. If I set power supply voltage to 0V (to keep same voltage) and current limit to some value.
Would it limit the current? Can I damage power supply by doing it? If I set positive or negative voltage would it still work the same?


texts: Need help with small circuit to convert signal to audio

texts: I'm an engineer but not an electrical engineer, so I have a basic understanding of electronics, but no serious experience... I am going to buy an EMG kit here, but I want to connect the output to a speaker, so I can hear (hopefully) when the muscle will contract/relax. Where can I get help on putting together whatever is needed for that sound output?


texts: Question to "Start-up into resistive load" diagram of LTC3106

texts:
There is a diagram on page 7 of the LTC3106 (Datasheet) named "Start-up into resistive load" and i couldn't find any explanation on the internet how to understand it.

My assumption is:
This diagram shows what load is allowed at the output of the ltc3106 for a given Vin at start-up without getting any problems.
So this means: if i have 100Ohms load, the ltc might get problems at start-up with 3V Vin.

Is this right?


texts: 7 segment display for hexadecimal numbers using PLAs

texts:
I'm trying to design 7 segment display for single digit hexadecimal numbers using PLAs but I am getting more than 16 product terms .If I implement using PROM it uses exactly 16 product terms(all min-terms). My question is:

1.Is there a calculation error from my end when I'm getting more than 16 prod terms.
2.IF 1 is not true, then is it that in this case using PROM is better option than using a PLA.As it requires lesser hardware.

I'm not actually using an IC but trying out the designs on paper.Please let me know if any clarifications are required.


texts:
Let me explain.  My son has a small typical night light that occasionally will go out, even if the bulb isn't dead.  Usually I'll tap on it repetitively or shake it to get it to work again. When I hold it under another light,  I can see the "coils" or string-looking things moving around uncontrollably, unattached to the points.  Now, here's the weird thing.  Sometimes, when I get it to work again, it will actually appear brighter than before.  Usually it's an orangey-yellow dim light, but after it goes out and I "fix" it, it becomes whiter and brighter.  How can this be?  Is it because the coils are no longer connected in their usual triangular shape, instead forming an irregular shape?  How could that effect it?

It looks something like this.  Just your average night light


texts: How do solar inverter systems easily add AC power sources together?

texts:
I understand DC power more than AC power. I know that given multiple DC power generators, easiest way to sum them is by connecting them in series. In paralel you'd need every generator circuit to protect itself from reverse current coming from other generators.

But I'm currently learning about solar PV systems and noticed that 'net metering' is just us putting our inverter paralel to the grid.

Thing is I am really not knowledgeable enough about AC to make this oversimplification - is it really that easy?


texts: filter whose gain increases from minimum to maximum for frequency 400Hz to 1kHz

texts: I want to design high pass filter whose gain should increase from minimum to maximum ( minimum upto 400 Hz maximum for 1 kHz) linearly or exponentially. It must be an active filter and my input signal is square wave. How do I design the circuit?


texts:
I was trying to understand the CMOS tri-state buffer internal structure with logic gates...

The image is similar to this one:

Anyway, I'm not understanding the logic I think something is escaping:

So imagine that I put the Enable in Low (0). In the NAND it will appear a Low and whatever the value I choose for the Input I will get a Low that will be negated and become a High (1)... But won't that activate the circuit? And when the control is 0 it shouldn't right...

The NOR function appears to work correctly...

Sorry if this is a kind of dumb question I'm starting my studies about digital systems...

Thanks!


texts:
This is what I see when I select and move an entire group in Eagle 9.6.0  .

General Perspective:

On the other side:

Another example:

What is the white line shooting out of the board's boundary?


texts:
Is there a list with the logos which appear on some power adapters?

I have two adapters and I'm wondering which one is better for my application. I'm interested especially on the output EMI filtering.

The adapters are here. One is China made by Creative and one is made in Germany (I couldn't identify the producer). My question is which of the two adapters has a better quality, judging only by the logos on them?


texts:
I want to be able to perform tests on assembled PCBs with a custom tool. the test would take seconds, and would be done manually by connecting a cable between the tool and PCB.

My question is what sort of connectors or similar are used for this purpose? For example, to keep costs down I presume a common method is to avoid using any connector on the PCB, and rather have some bare pads on it which some sort of specialised tool could latch onto. Are there any standard solutions for this?

Specifically for my application I would probably want about 10 connections: all low voltage, current under 2A, no high speed data or sensitive analogue signals.


texts:
I have two stepper motors (ripped from old scanners) and two L298N ICs. I have to connect these motors to the STM32 MCU, and I'm going to use this scheme:

I want to make one board for two motors just to save the space, the question is: Is it safe to connect L298Ns directly? I mean, do I need to use some diodes or something?

If it's possible, do I need to double Vsupply (e.g. 24V instead of 12V)?


texts: Has anybody used STM32F417IG microcontroller with 1.8V input supply?

texts:
https://www.st.com/resource/en/datasheet/dm00035129.pdf
Currently, I am using STM32F417IG with a 3.3V supply. If I want to use a microcontroller with a 1.8V supply to avoid level translators in the new design. Is there anything I should consider if I change the supply voltage to 1.8V from 3.3V?
If anybody has used stm32 with 1.8V as an input supply. Please help me with this.
Thank you


texts: Is this alternative relay flyback diode path good enough?

texts:
This question is about an alternative path for relay flyback diodes.

I plan to drive panasonic 12VDC CP1-12V relay with a NUD3160LT1G power MOSFET and the NUD3160LT1G datasheet says because the MOSFET comes has protection diodes, there is no need for a "free−wheeling diode" to drive an inductive load.

My question is, is it good enough to have this topology of flyback path through high voltage zener diodes and ground and +12 ground rails or should I connect a reverse diode directly on the relay's coil anyway.

This is for a non critical one-of audio application in my car. Cost is not an issue but I would prefer avoiding an additional diode if possible. The NUD3160LT1G will be driven by a 5V ATMEGA328P MCU if it maters.


texts: Why CycloConverter circuits are used as heavy duty drives for high power applications?

texts: is it due to the high power applications being slow at their functionality ? i know that CycloConverters can only lower the voltage/frequency of the source , and by that it will reduce the speed of the Induction Motor while keeping the torque constant. But why did we choose the CycloConverters specifically for High power applications and not other power electronic drives ?   Thanks


texts: Why are pull-up resistors required to be connected to the 2 lines of I2C?

texts:
Without pull-up resistors connected to the 2 lines of I2C, I2C communication fails. Why is there a need to have pull-up resistors for I2C? In contrast, UART and SPI do not need pull-up resistors.

Another side question is how does one choose the value of the resistor?


texts: Series connected MOSFETs effect on the channel length

texts:
I understand that connecting two NMOS in series for example increases the transistor channel length in concept. But consider having two series connected NMOS with the same channel length "L", can we say that this configuration is equivalent, in power consumption and resistance, to a single NMOS transistor with channel length of "2L"?
And how we can calculate the equivalent channel length of N connected NMOS with the same channel length of "L", is there like a formula or equation to get this?

Thanks a lot.


texts: Why does rectifier output is showing DC instead of pulsating DC

texts:
I am using below circuit for PFC.
Before connecting coupled inductor's auxiliary output to the IC's Vcc, I wanted to make sure that it is coming properly or not.

So when I probed the red dot in the circuit below, it is showing 0V, doubtfully when I probed blue dot in the circuit below, Instead of pulsating DC at the point, I am observing a 312VDC, straight line. I am suspecting that may be the reason the inductor is not giving any voltage to it's auxiliary winding because there is no change in current at the primary winding.
(The measurement of the voltage is done in oscilloscope).


texts: Power supply and equipment that I should have to fit all small electronic projects

texts:
In the last 2 months I have been wasting money in power supplies, I have been learning a lot and spending a lot of hours every day with robots and electronics so I upgraded my motors and my projects accordingly, which also needs an upgrade on the power supply (I have a software development background so I could focus in learning only the electronic part of it).

I always find myself struggling with the power supply part of it and every time that I buy a new one in a couple of weeks it is not enough anymore, so my doubts are:

I understand that if I'm using 6 motors connected to the same power supply and every motor (for example) requires 6 volts and 2 amps I need a power supply that provides 6 volts and 12 amps (is my understanding correct?) so I assume that I need something like this ? (I couldn't find another thing with 10+ amps but only 6-8 volts)

For what I understand you can have problems with too much voltage (you can fry the motor) but amps are ok as everything just takes what it needs?

What would you guys use if you have the intention of working in different projects that require different motors, voltages and amps, do you aim to buy something specific for every project or something that will work with anything? Or a combination of things? What would you guys recommend me to buy and always have in my "tool box" for this purpose?


texts:
Other than obviously non-trivial problem of writing the software, is there any practical reason why the GPIO port of a Raspberry Pi couldn't be used as a JTAG programmer? I ask because I'm doing some hobby work with interfacing a CPLD to my  Raspberry Pi and it would be convenient to be able to program it directly rather than using a separate JTAG device and computer.

Are there any issues with voltages, timing etc...?


texts: Help with understanding Current, Voltage and Resistance

texts:
Is my analogy correct:

With a highway as an example, would

Resistance (ohms) be the number for lanes in one direction
Current (amps) be the density of cars on the road
Voltage (volt) be the speed limit of the road

What I find confusing is current and voltage. Current, if it can relate to density, could be a factor of voltage?


texts: I always use the internal oscillator that pics have as I have never found the need to run anything at higher frequency than 8 MHz (which is the fastest the pics I use tend to be able to go). Are there any reasons, beyond going above 8 MHz, that mean I should use an external oscillator? It just seems like one more thing to go wrong to me but I'd be interested to hear what others do.


texts: Charging capacitors in parallel with a battery

texts:
I am trying to figure out a system to charge a series capacitor bank without too much current going through the capacitors. I had the idea of putting a battery in parallel with the series capacitor back to divide the current, but since the current through the capacitors is \$i=C\dfrac{dV}{dt}\$, and the battery would have a close to constant voltage making \$\dfrac{dV}{dt}=0\$. Would this effectively divide the current or would it all pass though the capacitors because of the constant voltage of the battery?

The rest of this is just for application specific reason and not as urgent as the main question above. Thanks for looking =)

The reason I am trying to do this is to cut the cost of buying more super capacitors when they are $50 each because another method would be to add more capacitors in series to raise the voltage level and reduce the current. Are there any cheaper alternatives?

I have 1 kW of power being converted down to whatever voltage level I need. The capacitors I am looking at are the Maxwell K series. They have a voltage rating of 2.7V each, with C=1500F and a current rating of 97A.  The cost of 4 is the upper limit of my budget.


texts: Medium-Distance Travel of Electrical Pulses over a Wire

texts:
I'm building a small morse code chip as a fun project, and I have a question about sending pulses over a wire. I was planning on using some speaker wire to connect a few of these PCBs over a somewhat long distance. I can buy packs of speaker wire that are either 16 or 24 gauge, and either 100 or 50 feet or even longer (longer is preferable). One wire is for data, the other is ground. The load at the other end is another microcontroller (I might have multiple branches with more than one of an identical microcontroller circuit).

The power source I was going to use for this circuit is a CR2032 coin cell battery. It can provide more than enough current to power all of the components in my circuit.

Before I go about buying a bunch of components, I want to get some advice on a few things. Firstly, I want to have the option of sending square wave pulses from a microcontroller. Would it be better to use a transistor to switch the connection to the wire on and off, or would it be adequate to simply send pulses directly from the microcontroller pin? I'm also unsure about my power source. I know that the CR2032 coin cell battery can deliver only very small amounts of current, so would it be best to upgrade to something like a LiPoly? Or would the coin cell be sufficient to send pulses across the wire? Additionally, are these power sources even adequate for such a large wire? I would ideally like to avoid having to worry about voltages over 5V and alternating current, which I know propagates down a wire more efficiently.

My last question is simply about range. What kind of theoretical maximum wire length could I send data across given the batteries I described? If I remember correctly larger diameter wires have less resistance, but since the 24 gauge wire is cheaper I would like to purchase that if it won't affect the range by too large of an amount.

Thanks for your help!


texts: Are external pullup resistors required D I/O pins on RN4870/71?

texts: Are external pull-up resistors required on RN4870/71 for pins like "P1_1"? The datasheet mentions D I/O pins being "pulled-high", is it pulled high with internal resistors or programmatically from the microcontroller it's connected to or are external pullup resistors required?


texts: Aside from cost, is there any disadvantage to using thicker wire than required?

texts:
Say I've calculated the minimum wire gauge necessary to give me an acceptable voltage drop over my length of cable run at the voltage and current my application will use.

Are there any disadvantages to using thicker cable, aside from cost? Is the answer different for AC vs DC? For power vs signal transmission?


texts: Switch off branch of a circuit when voltage is present in another branch [power path management]

texts:
I want to convert a circuit that runs on 6V DC (from an intermitent power source) to a battery-operated one, by adding a Sealed Lead-Acid (SLA) battery.

This would fulfill the following scenarios:

When intermitent source is active, it powers the system load and recharges the battery;
When intermitent source is shut off, the battery powers the system load;
When intermitent source is active but system load momentarily demants too much power, the battery provides that extra.

I designed this simple circuit (I am no electrical engineer), and identified a region where I would like the path to be "interrupted" or "switched-off" when VCC is present. The drawings are below.

Nominal VCC is tuned by zener to be 6.8V, suggested by the manufacturer to be a good float voltage to the expected temperature range of use where I live.

So the question is: what components, in what configuration, could be used to "sense" VCC present, and shut the red-circled branch?

I have seen some designs using a mosfet, but I'm not sure where should I put one in this circuit (where to connect gate, drain, source), and if any other component would be needed, and their values.

General View:

When external source ON:

When external source OFF:


texts: The official page of Wikipedia mentions that reverse saturation current is a part of minority current caused by the drift of charges. I am really confused about this. In class, we have been taught the value of the reverse saturation current using equations of diffusion current.


texts: Finding the current of an open circuit for Thevenin Equivalence

texts:
I'm trying to find the Thevenin voltage of this circuit. To do this, I need to find the current of this circuit.

The circuit is open at the right, which implies that there is NO current flowing through the 16 ohm resistor.

There is current flowing through the 20 ohm resistor at the very least, and I think to at least some extent the 80 ohm resistor.

Apparently, the current is 1 A, but I don't agree with this. If I track the flow of current, it goes downwards from the emf with current I, then it WOULD be split into, say I2 and I3, but the current can only really travel upwards, so it shouldn't split. The same logic should apply to the top junction. Because of this, I argue that to find the current, the 20 ohm and 80 ohm resistors are added in series, because the same current flows through them, which gives a current of 0.2 A. However, the worked example's solution merely does I = 20 V / 20 Ohms to give 1 A.

I would be okay with this if no current is flowing through the 80 Ohm resistor, but when the solution turns to finding the current from either end point, A and B (which, if I could label in the graphic, are at the circles on the far right), as one needs to do to find the open circuit voltage for the Thevenin voltage, the 20 ohm and 80 ohm resistors are added in parallel.

So I seem to have a mental block - if there is no current traveling through the 80 ohm resistor, why are we adding it in parallel with 20 ohms when finding equivalent resistance to find V_oc?

Also, why wouldn't there be current through the 80 ohm resistor in the first place? And if there is, why don't we include it in our current calculation?


texts: Lowering the output of high amp current sensor for low amp use - good or bad?

texts: By increasing the value of burden resistor or turning the wire several times around the CT an output can be increased. But is it a good practise to lower the high current non-invasive current sensor for low amp application in terms of harmonics, phase error and etc?


texts:
I'm trying to modify a Nikon SB-26 camera flash to use AC power instead of batteries. I have a setup similar to this with two dummy batteries connected to wires that lead out of the battery housing. Instead of hooking up the wires to an external battery pack though, I've connected the dummy batteries to this variable voltage 300mA AC adapter. My results with different voltages are as follows:

1.5V: nothing
3V: the unit turns on and all of the menu options work, but the flash itself doesn't charge
4.5V: the unit does not turn on but beeps about once per second
6V: the unit beeps at about once per second and also quickly turns on
and off at the same interval.

I was about to call this experiment a failure when I decided to hook the flash up to some of the outputs on this Radio Shack electronics learning lab (which is powered by AA batteries.) Sure enough, when I plugged it into 4.5 volts, the flash was powered and worked normally (although the flash charged a little more slowly than normal)

This leads me to believe that I'm using the wrong AC adapter. My ideal solution would be charging the flash much faster than it does with the electronics learning lab and closer to how quickly it charges normally. Does anyone have any recommendations for what adapter I should be using instead? Even if you don't have a specific answer, any information on a good troubleshooting/honing path to proceed with would be extremely helpful.


texts: PIC interrupt on change never enters the interrupt routine

texts:
Hello I am using PIC18F26K83 and I have a button on RC7 pin. That is why I cannot use a normal interrupt. But according to datasheet interrupt on change can be used in this pin. I could not make it work so I tried to make a code with interrupt on change which was supposed to make the LED light. But the code never enters the interrupt routine. Here is the code:

   #define switch PORTC.B7
#define led1 LATB.B0
#define led2 LATB.B1
#define led3 LATB.RB5
int counter;

 void Clk_8Mhz(){
   //8 MHz clock
          //  OSCCON1 REGISTER
   NOSC2_BIT=1;
  NOSC1_BIT=1;
   NOSC0_BIT=0;//HF INTERNAL OSC
   //OSCFRQ REGISTER HFINTOSC FREQ. SELECTION

OSCCON1 =0b01100000; //HFINTOSC, Divider =1;
    FRQ3_BIT=0;
   FRQ2_BIT=0;
   FRQ1_BIT=1;
   FRQ0_BIT=1;    // 0011 :8MHz     //0100 = 16 Mhz
  }
void main (){
TRISC.RC7=1; //Button pin is output
ANSELC.RC7=0; //Button pin is digital

TRISB=0x00; //B port is output.
LATB.B=0x00; //All B port is initially zero.
//RC7 IOC

//Interrupt initialisation
INTCON0.B5=0; //Interrupt priority disabled
IOCCN7_bit=1; //RC7 pin is negative edge
IOCCF=0x00; //Clear the Interrupt on Change Flag
PIE0.B7=1; //Interrupt on change enabled
INTCON0.B7=1; //Global high priority interrupt enable

   Clk_8Mhz();

while(1){
delay_ms(10);//Wait for interrupt

}

}
void interrupt(void)  {

led1=1;
led2=1;
led3=1;
}

Probably I am missing something very obvious.
Edit: I use Micro C
Edit2: I changed to code like above. Still interrupt does not occur unfortunately.

These are 2 images of the schematic, I could not find the whole part but schematic of PIC and switch is in here:


texts: What is the back voltage generated by this inductor in this practice problem?

texts:
The circuit is in a steady state, and the switch is lifted at t=0. In (a), i calculated the current i and the voltage v at the instantaneous moment that the switch is lifted. The current is 2A and the voltage is 12V.

For (b), I need to calculate di/dt at the same instantaneous moment. I can reach that value if I can figure out the back emf (VL) of the conductor. Using Kirchoff's Law on the loop present after the switch is opened, I derive the following equation:

VL - 10(2) - VC = 0

Where VL is the back voltage given off by the inductor, 10(2) is the voltage drop across the two resistors in series, and VC is the voltage across the capacitor. Solving for VL then gives me 32V. It this correct? This seems like an unlikely answer. I believe my signs in my kirchoff equation may be wrong. Can someone check this for me?


texts:
Suppose we have this circuit:

simulate this circuit – Schematic created using CircuitLab
The BJT transistor is in saturation mode.Which are the equations which help us find the different currents(Emitter , Base and Collector current)?
I only know how to solve BJT transistors in forward active mode and I couldn't find anything online.Help really appreciated


texts: Driving IR led from 3.3V GPIO using 2N2222 transistor

texts:
I am using the following circuit to drive an IR led from a NodeMCU.

simulate this circuit – Schematic created using CircuitLab

However, im seeing the following on my scope. (Please ignore the LED model on my schematic)

I don't seem to be able to pull the output low quickly enough.Is my schematic right? What am I doing wrong?

Thanks in advance


texts: Reducing Thermal Pad Size Below Official Footprint - Can It Create Manufacturability Problems?

texts:
I'm using a DP83867 Ethernet chip by Texas Instruments in an S-PQFP-G64, 10 x 10 mm package, the mechanical dimension and its recommended footprint are shown at the end of the question. As shown, the package includes a "4.44 x 4.44 mm" thermal pad, and the recommended stencil opening is "4.44 x 4.44 mm" as well. However, TI recommends an "8.0 x 8.0 mm" copper area on the PCB.
Unfortunately, the controller it's interfaced to has a mirrored pin order, a direct connection at the perimeter of the package is not possible without numerous undesirable vias and trace crossing. A more ideal routing is to fan the signals out via the bottom of the chip. but the "8.0 mm x 8.0 mm" copper area in the official footprint doesn't provide enough clearance. My solution was reducing the thermal pad to "7.0 x 7.0 mm", the extra 1 mm allowed me to route all signals within the design rules.
I have already received the PCB and assembled the board manually without any difficulty. After some minor debugging, the board is now fully functional.
Question: Is it an acceptable practice in PCB design? If I reduce the thermal pad size below what's in the official footprint, hypothetically (it's only a personal project and won't be manufactured), if I send this design for production, will it create any manufacturability problems in reflow soldering? In my opinion, there isn't anything obvious, downsizing the pad may reduce the soldering quality in a small QFN package, but in this case, the copper pad (7 x 7 mm) is still significantly greater than the thermal pad (4.44 x 4.44 mm) on the package. But I may have missed something.
BTW, increased thermal resistance is obvious, but let's assume it's negligible here.


texts: Have you ever fried a wi-fi router by leaving it to work without its external antennas?

texts:
I wonder if a wi-fi router can be damaged if its external antennas are unscrewed?

Have you ever damaged such a router leaving it to work without antennas, like this:

Source

I know that there are numerous questions regarding what happens if the antenna of a radio transmitter is disconnected. However, I have not found until now people that ruined a wi-fi router just by disconnecting its antennas.

Do those two wires that run between the final stages of the router and the antenna connectors (see the picture) radiate power and save the router in case one or both antennas are unscrewed?


texts: What does "(+5V=5, +/-5V=10)" mean in the context of op amp supply voltage?

texts:
I've been trying to see what to expect if I use a single supply of 5v on the tl084 op amp and, while reading about it, I came into a small mystery that I can't seem to solve. On the site of Texas Instruments, it says that the tl084 has 7v minimum supply voltage, and 36v total maximum supply voltage. On the side of the name of both fields it says "(+5V=5, +/-5V=10)". Here is the link: http://www.ti.com/product/TL084

I've been trying to understand what that means. I read the spec sheet, but it doesn't say anything about "(+5V=5, +/-5V=10)". Furthermore, the spec sheet doesn't mention the 7v minimum supply (it recommends +5v and -5v supply, but it doesn't clarify if that number applies to single supply). I think I can solve the question of what happens if I supply 5v myself (I'll just try it and do many tests if it comes to that), but now I'm really curious about what does "(+5V=5, +/-5V=10)" mean. I imagine it must not be something terribly useful, but, you know: the more you know, the more you know.

Thank you, good people.

--
Edit

Here is the screen shot that was required:
Screen shot from http://www.ti.com/product/TL084


texts: Which pins does the Efcom 1.2 GPRS shield require to be connected in order to work?

texts: I have this GPRS shield for arduino and I'd like to use it later on with some other standalone microcontroller. I have not been able to get it working though without connecting it to arduino and I could not find any info about the pins which are required by the onboard SIM900 chip to function properly. I have tried to get it working with arduino using jumper wires with absolutely no luck. The leds do light up, but the board does not seem to receive any issued AT commands. So which pins should I connect out of all the available pins on this board as the only requirement is that the external microcontroller should be able to send AT commands to the board to operate it?


texts: Can a multimeter really accurately measure the output current of a SMPS?

texts: Most multimeters are bandwidth-limited to below 1khz while the current ripple of most SMPS is well above that. Even benchtop multimeters usually have bandwidth up to ~300kHz, which is not enough to accurately measure the output current of a high-frequency SMPS (800kHz or 1MHz). Yet measuring the output current of a SMPS with a multimeter is very common practice. So what am I missing here? How can measuring the current of a decently large ripple at a frequency higher than the bandwidth of your measuring device be accurate?


texts: "Multiplexing" thermocouples to an IO board

texts:
I'm trying to solve a problem on a project for one of my customer, 'cause we are having hard times to find an appropriate solution.

He needs something really simple (more on this later) and as we are both not much into electronics, all we can do is to call "companies with a name" for offer on their hardware, and end up with things that are really perfect to land on the moon but really overpriced for our scenario.

I'm trying to find a different alternative, thus this question.

Scenario:

40 thermocouples to be sampled (brand unknown, as they are 20 years old and nobody remember were they come from, but this is not the problem 'cause we can always change them all)
Required sampling precision: +- 0.5 degrees 2 Celsius degrees.
Required sampling speed: a whopping once every two minutes. That is, 120 seconds divided 40, an astonishing sampling rate of one thermocouple every three seconds :-D

So, it's obvious we don't need 20k euros equipment, but it seems that there is nothing simple out there and given that we need 40 input, prices are going up really quickly.

On top of this we still need a few digital outputs (3 or 4, still unclear) and some analog inputs to sample some voltages, and all this stuff will be driven by a custom software on a Windows PC. So to the question (finally)...

In this scenario, can buying a simple I/O board and somehow multiplexing the thermocouples to a single analog input feasible? Do Multiplexer with 40 inputs exists at all? (P.S. the multiplexer should be controlled by the PC, ideally)

Update after gathering some more information with the customer

Ok, at the end I did a lot of work and I've been be able to get all the info I needed. Seems like there was some misunderstanding with the customer, now everything is clear and I can give more info.

First of all, the required precision is 2 Celsius degrees. As I've noticed someone pointed, it the temperature range is between 100 degrees: That is between room temperature room temperature+100

Currently used thermocouples are standard T type, from Tersid. As of now the 20 years old thermocouples are connected to a 20 years old I/O board, by 20 years old, 10-15 meters long wires, in an environment with a lot of electromagnetic noise, and work like a charm. Don't ask me how, I have no idea :-D


texts: Sequential Switching Shunt Regulator logic

texts:
I feel I'm so close and yet so far from understanding the control logic of shunt regulators. I will use as a reference "Sequential Switching Shunt Regulator for Satellite Power Control System" by A. Kamel et al., but there are several similar others.

I get how they detect a change in the load demands by sensing small changes in the main bus voltage, amplifying them and choosing the operating domain of the system. If there's an excess voltage then the batteries are charged, if there's even more then some energy is dissipated. On the other hand, if the voltage drops too low then the batteries come to help.

The question I cannot solve comes now: each error value corresponds to a predefined number of connected strings (you can see it in Kamel et al., table 2, I cannot add more links to the question). If for example a voltage excess is detected then some of the strings are shunted in order to limit the power. But by doing so, if I'm not mistaken, the voltage of the main bus would come down, and the error voltage with it. The system would think "with an error value this low I need to have more strings activated!" so more strings would connect, and you would get a voltage excess again. The system would, as I see it, be constantly jumping from one domain to another. Is that what would happen? Does that make sense? Or maybe I'm making a wrong assumption somewhere in my reasoning?


texts:
I'm trying to read files from a NAND flash (K9LAG08U0M) that I took off an old MP3 player, so far I've been able to read the NAND contents successfully by interfacing it to my PC as a USBMSD (Mass Storage Device) using an ARM microcontroller.

The problem is when I connect it, I get an "unknown partition table" error, looking closer the first page it doesn't seem have a valid MBR, after some searching I was able to locate the MBR at offset 0x7e800 (page number 253), this is what I get when using file(1) on that block (the MP3 was formated with FAT32)

  x86 boot sector, code offset 0x58, OEM-ID "ALiOS1.0",
  sectors/cluster 2, reserved sectors 34, Media descriptor 0xf8, heads
  255, sectors 248448 (volumes > 32 MB) , FAT (32 bit), sectors/FAT 963,
  serial number 0x30a3239e, unlabeled

My question is, why isn't the MBR stored on the first page ? does this mean that the controller remapped the first block to another one ? if so, is there a way for me to figure out how bad blocks are managed (without the original controller) so I can do the same mapping in my code to read the filesystem ?

Thanks.

PS: I tried checking for bad blocks to see if block 0 is bad, according to the datasheet an initial bad block is identified by a non-FFh byte stored in the spare area of the last page in the block, but when I tried that almost 80% of the blocks show as bad blocks and the first block is not one of them, does this sound like a reasonable ratio to you ? or am I doing something wrong when checking for bad blocks ?

Some info about the flash:

8192 blocks

128 page per block

2K pages + 64 bytes spare area.


texts: How to increase voltage drop across LED?

texts:
Hi I am using LED of 1550nm(Datasheet Link Attached) thorlabs.and voltage drop which I am getting across it is 0.866V. I have connected a 60ohm resistor in series and voltage which I've provided is 5V.

How can I get the rated voltage value?LED155E Thorlabs


texts: How to convert Li-ion battery voltage to 1.5 V?

texts: I want to use Li-ion batteries to power devices that work with AA (1.5 V) batteries, to have best autonomy and to be able to recharge it easily (using a battery manager module). I had thought of a buck converter module, but in the market I cannot find one that supports 4.2-3.3V in input and output of 1.5V. How could I get 1.5V from Li-ion batteries?


texts:
I have a Sony Sony DSX-A110u which is a car stereo having 4*55W Speaker out and a Sub-woofer out.
The subwoofer-out port it a female RCA jack. which looks like this

-

I am using the sub-woofer out jack to feed in a another stereo-subwoofer amplifier which takes in 3 wires Left, Right & Ground as a input

I have given input to the other amp. like this

THE PROBLEM

As you can see the car's stereo subwoofer output both channel separatel via RCA jack so naturally, To give input to my other amplifier, I joined the ground pin of RCA cables to make it 3-pin stereo format.

  Now the problem is, As soon as I join the ground wire of the both RCA out, The volume output of other subwoofer amp gets really low and makes a Tick-Tick noise once every second, Like some digital signal has been passed with the audio signal. Its more noticeable in higher volumes.

The tick-tick noise continues even when nothing is playing on the stereo.

The amplifier works fine in MONO mode otherwise! (Using just 1 RCA jack)

Can anyone tell why this is happening and what can I do to fix it?


texts: Does lifetime of tungsten incandescent lamp shorten by every turning on, directly connecting to electric grid, and how much?

texts:
Does lifetime of tungsten incandescent lamp shorten by every turning on, directly connecting to electric grid, ie not using special device to turn it on smoothly, and how much? It was said to us in school that it shortens its lifetime.

How much it (lifetime shortening) is compared to lifetime shortening by stable ligthting? If a lamp user goes away from a lamp, planning for some time of absence, how much time of absence worth turning the lamp off and then on, for the time of absence?

When it is too long, it worths, because saved electricity is more expensive than the increase of price by having to buy new lamps more frequently (because of such behaviour). When the time is very short, it also worth, because lamp does not get cooled and do not get shock.

Do not take in account that frequent flickering causes decreased efficiency of getting light per amount of used power. (Ie if user for some reason makes frequent flickering, calculate only price of electicity and price of lamp, do not calculate amount of light produced; and it anyway produces heat efficiently and heat+light may be goal of user, anyway, consider it is ok for him since he does so).

I have found also confirmation of that the lifetime shortens in an answer on this site: https://electronics.stackexchange.com/a/214397 :

  During rapid switching the filament would not cool completely before
  the next switch-on so it would not be stressed so much. The longer the
  'off' periods the harder it is for the lamp.

  My domestic experience was that lamps on dimmer switches lasted
  'forever' relative to the other lamps in the house. This was due to
  the rotary dimmer being turned up over, say, half a second and
  gradually increasing the current while the element warmed up. There
  was no sudden inrush current.

And this question is similar to that question, but in content part of the question it is asked about 120 hz flickering. And an answer there is already accepted. And the 2 answers there do not answer about how much the lifetime shortens, ie there is no formula nor links to investigation result papers are given.


texts: Aluminum Electrolytic Capacitor submersed in synthetic (PAO) oil

texts:
We are testing solar water pumps which have the 3phase inverter for the BLDC in the down hole pump. The boards (one power board, one controller board) are submersed in the lubricant oil that is used for the motor. This oil is a synthetic (PAO) oil, but do not know if there are additives. (we do not make the electronics or the pump)

The BLDC controller and the Power board (with three half H-bridges) all have aluminum electrolytic capacitors. I am particularly concerned about an increase in the ESR of the bootstrap capacitor used on the high side gate drive on the N-channel FETs.

We have pumped water for over thirty days, but have had some failures,

High and low side FET shorted on Half H bridge
Motor failure (still under investigation)
Controller failure (still under investigation)

There is a brief note in the specifications indicating  that capacitors should not be exposed oil(it appears all the manufactures copied the same notes from somewhere)

  Confirm the environment does not have any of the following conditions...
  Where capacitors are exposed to oil or an atmosphere that is filled with particles of oil.

So submersing them in oil doesn't sound like a great idea, but the details are a bit light on the expected failure mechanism (like oil penetrating the electrolyte changing ESR or spoiling the anode oxide)

What type of failure would be expected when operating an aluminum electrolytic capacitor(wet) in synthetic oil.

I have requested information from four different manufacturers of aluminum electrolytic capacitors , but have got no response.


texts: Can a phase converter (1 to 3) convert directly from DC to three phase or does it have to invert it to AC first then convert to three phase?


texts: BJT Amplifier with Emitter Bypass Capacitor Design

texts:
I am trying to design a BJT amplifier. The circuit is shown below with its parameters.

beta=180
RL=20kΩ
VA=0 (early effect can be ignored)
VCC=15V

There are three constraints listed below:

Swing voltage of Vout must be between 22V and 24V (peak to peak)
Voltage gain must be equal to 20.
Power dissipation by resistors must be under 0.2 Watt

As you may understand this is a project and I do not expect the whole solution. But useful hints or calculation steps would be so useful. I want to learn,

Which part of this circuit should I design first?
How do I adjust peak to peak voltage?
How do I approach power dissipation considerings?


texts: LTSpice error when simulating behavioural voltages

texts:
I've been receiving this error whenever I want to create a voltage source affected by another voltage source:

It says here that V1 is an unknown symbol but clearly I've inserted a voltage source V1 in the schematic.


texts: Which IC produces PWM that can be filtered into sine wave?

texts:
For a DC to AC transformerless power supply, I am trying to find a specific type of IC that produces PWM that can be filtered into sine wave.
What I can find in most websites is an MCU that has to be programmed to produce such PWM.
I am wondering is there any off-the-shelf IC that available so that I don't have to do the MCU programming.
I don't need fancy PWM, just a single purpose IC that produce PWM which can be filter into a sine wave.
To be more precise, the square wave pattern I’d like to generate is shown below:


texts: How exactly does the grid handle small deviations in power consumption?

texts:
I've heard many times that the grid electricity production and consumption must be balanced and imbalances lead to overvoltage or undervoltage. I've never seen an explanation of that phenomena from energy conservation law standpoint.

Suppose I have a grid with exactly one gigawatt generation and exactly one gigawatt consumption. Let's pretend there're no losses - all the conductors are superconductors. So whatever is generated is fully consumed.

Now someone switches his one thousand watts space heater off. Generation now exceeds consumption. Although it's a relatively small increases there's still some imbalance.

What happens? Where does this excess power go?


texts:
I just have a question about this simple circuit or example: http://www.555-timer-circuits.com/flashing-led.html. I just don't get 1) why do they use 9V battery to power a single red LED light. 2) why there need to be a 1k resistor before the led?

Is there anyway to power a 12V LED (current: 0.08A) by 12V battery efficiently (optimal brightness) or i have to use a slightly higher voltage?


texts: How to handle nested final result code in AT-command text?

texts:
I am writing a parser (a finite state machine to be more precise) for AT-commands and I don't see how to handle a particular corner case:

Here is the specifications of the modem communication:
When the DTE sends an AT-command terminated by <CR> (like ATE0<CR>), the DCE will optionally answer an information text response between <CR><LF> characters and finally give the final result code (like <CR><LF>OK<CR><LF>).

My algorithm is like this:

do {
    line = readLine(serial_modem);
} while (! is_final_result_code(line))

Here is the corner case:
Suppose I send the command to read an SMS message and that the information text response (i.e. the SMS text) itself contains the sequence <CR><LF>OK<CR><LF>.

Then my parser will think wrongly that the first <CR><LF> terminates the information text response while the next part is the final result code.

Do I miss an important information on how to handle this case properly ?


texts: Why is rectified open circuit voltage much lower than with a load?

texts:
I rewound the secondary of a 850 watt microwave oven transformer (MOT) so the open circuit voltage (OCV) after rectified by a full bridge rectifier is 14.4 volts. The laminations are not shorted. When I hook the output up to a 12 volt lead acid battery, suddenly the voltage jumps to about 17-18 volts. This is very frustrating. When I hookup a 25 watt 12 volt car battery to the rectified output,  the light works great and the voltage is about 12.9 which would be expected. So for resistive loads everything is fine (assuming battery is not resistive load).  Can someone please tell me whats happening here? Thank you very much in advance.-Kurt

Edit Addition:
I guess my main issue is that the open circuit voltage is LOWER than the voltage with a load, but only when connected to a battery. All other resistive and inductive loads, the voltage drops as expected.


texts: What is the appropriate capacity of a matching step down transformer for a power amplifier?

texts:
I have a TRIO KA-9900 amplifier which is the Japanese equivalent of a KENWOOD KA-907 amplifier.

My amplifier runs on Japanese AC voltage.

What is the appropriate capacity of a step-down transformer for use in a country that runs on 230v?

Here are the specifications:
AC 100V
400W
50/60Hz


texts: Using optocouplers and programmable resistors to control a gamepad

texts:
Let me preface by saying that I'm a C developer by trade, with very little electronics/hardware design knowledge.
I started working on a project to map Keyboard/Mouse to a USB HID gamepad with the idea of connecting it to a PlayStation 5. Originally I thought this would be mostly a software solution by creating a USB gadget gamepad device. But alas the PS5 locks down peripherals hard and it only recognizes the PS5 controller and other Sony licensed gamepads. I'm sure it would be possible to reverse engineer the USB packets and figure out how to emulate a full PS5 controller, but that is a large tedious task that is likely to break with future controller/PS5 software updates anyway.
My other idea is to open up an existing PS5 controller and wire up all the buttons and analog sticks and control them with Arduino (or Raspi) GPIOs. My thinking is that if I can get this working it would be a future-proof solution, that will not break with PS5 software changes. The PS5 console itself would also be electrically isolated from my hackery because the PS5 gamepad would connect over Bluetooth in this case.
The PS5 controller has 15 2-state buttons (on/off). and 6 analog axis (4 for analog sticks, and 2 for trigger buttons). There is also a touchpad but I don't want to bother with that.
My current thinking based on browsing around is that I could use 15 optocouplers for the buttons, and 6 programmable variable resistors for the analog axis. I'm sure I have more questions than I know, but lets start with:
Does that sound at all viable?
Can an Arduino or Raspberry Pi (3/4/zero) handle this many parts? It seems there might be enough GPIOs (especially on raspi), and if not I could wire up a couple boards and have them sync up over uart or some other method. But how about power consumption of that many optocouplers?
The optocouplers would entirely isolate the Arduino from the gamepad which sounds great. How about programmable variable resistors for the analog axis? Would those work in this project? I'm thinking of something like https://www.digikey.ca/en/products/detail/analog-devices-inc/AD5220BNZ100
Is there a better approach?
Thanks!


texts:
Using PIC32MZ2048EFH144 MCU.

Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/60001320D.pdf

12 Bit ADC

The board has 8 DMA Channels(Programmable/Dedicated). I am interfacing 10 microphones, therefore i need 10 channels to connect my analog microphones.

How do I connect two analog microphones to one port on my board. Multiplexing? How so...? Any references you guys have?


texts:
So sharptooth has a question up for creating cheap charger units that uses battery packs to charge a phone:

Is designing and producing a dirt cheap charger really that hard?

My question is the other way round, how would you design a cheap NiCad charger with the only requirements being that it shouldn't damange your batteries even if left in the charger for extended periods and that it should be as cheap as possible. Here's my shot at it:

It's a simple current limit with diodes in parallel to the battery to protect against overvoltage by bleeding off current when the voltages reaches around 1.4V. (i.e, single NiCad)

I've added Russell's ideas to the mix and came up with the following, doubt you can go cheaper than this, it meets all the requirements and can be powered from just about anything as well as turning off when the batteries (two or more in series) reached the set threshold. The only way to go cheaper I would guess is to use a constant voltage scheme instead but I'm guessing this will kill your battery a lot quicker, can anyone comment on charging NiCad using constant voltage?


texts: 125 MHz parallel bus in a double 2.54mm header

texts:
I have a BeMicro CV low cost dev board from Altera. It features a Cyclone V.

FYI: Schematics and gerber here

They routed impedance controlled differential lines to some dual 2.54mm standard headers.

See the at the top of the picture below:

It seems that they cared about the controlled impedance, and also the line lengths.

I would like to connect a 1000Mbit PHY with GMII interface (parallel 125MHz clock).

Can I plug a daughter board to this one and convey the 125MHz signals using a simple 2.45mm header?


texts: What's the difference between analog range and dynamic range in ADCs?

texts:
I'm doing a project for school where we need to select an ADC based on a variety of requirements. Two of these requirements, analog range and dynamic range, seem redundant to me.

From what I understand, the analog range is the voltage range of the analog input signal. However, the dynamic range is amplitude of a signal able to be handled, which seems synonymous to the analog range.

What is the distinction that I'm missing? I'm a bit confused because based off of this question, it seems like you can derive the dynamic range from the analog range.


texts: Meaning of numbers inside parentheses in Lattice Synthesis Engine Utilization Report?

texts:
I'm using Lattice Radiant 2.0 to synthesize a design. In the "Synthesis Utilization Report file", I see the following line:
                  LUT4    PFU Registers   IO Buffers   DSPMULT     EBR   Carry Cells
 toplevel    2752(267)          702(74)       22(21)      5(0)   30(2)      315(315)

The numbers outside the parentheses are pretty clear; that's just resource usage.
My questions:

What do the numbers inside the parentheses mean?
Is this standard notation for synthesizer outputs? If so, where can I find information explaining standard synthesizer output notation?

I've already looked through the following documents, but haven't been able to find anything (warning: links auto-download PDFs (Lattice's decision, not mine.))

Lattice synthesis engine user guide
Lattice Radiant Software 2.0 User Guide
Lattice Radiant Software 2.0 Help
Lattice Radiant Software 2.0 Tutorial

My only guess is that the number in parentheses describes how many resources could be optimized out of the design with more aggressive optimization strategies, but I have nothing to base that guess off of.


texts: Why does an LC-filter need two different capacitors and how do we calculate their values?

texts:
I am currently tasked with reverse-engineering a buck converter based on the LM2596 adjustable switch. On the PCB that I have, there is a following filter circuit (redrawn by me):

I did some research, and it seems that the two capacitors
are needed for better filtering. However, I cannot find any information on how those capacitor values are related.

Thus, the question - how can we calculate those capacitor values if only the switching frequency (150 kHz) is known? Are they really needed for filtering or did I make a mistake?

Thanks in advance!

EDIT: Here is the full schematic:


texts:
simulate this circuit – Schematic created using CircuitLab

At VM1 I theoretically expect about 1mV. When I connect with the opamp I get a voltage drop of 0.5mV at VM1, I get this values in simulation(theoretically). What is the cause of this (something to do with the 10MOhm) and what can I do to prevent this in the practical circuit.


texts: Reasons for constraining single-ended Op-Amp VCC when multiple power rails available

texts: If I am utilising an op-amp, say a LM321/LM324, say in single-supply operation as a buffer and have a multiple suitable power rails available then are there, assuming I do not expect to utilise the full output swing of the opamp for any of my rails and none of the rails exceed the maximum specification, any potential advantages to using a lower-voltage supply rail?


texts: The choice of method for constructing hardware monitoring and diagnostics

texts:
created a weight scale device.
I chose the software method for diagnosing my system. How can I implement it?

X1 is a load cell 5000 grams

DA2 HX711

D1 Atmeaga328

D2 shift register

H1 lcd display

What is the best way to test these items before each run?

How to test the system every time before starting.


texts: Is it safe to have two batteries in series on a solar panel system with 14.22v and 14.46v?

texts:
I have two batteries in series plugged to a solar panel system.

In parallel they used to balance each other perfectly.

But now i'm trying to have a 24v system and I have them in series.

They started both at a perfect 13.35v.

But just after plugging the MPPT, they don't keep the same voltage and i'm wondering what is the acceptable difference of voltage without being dangerous ? (considering i charge them at max 28.8v with an MPPT)

Now i have 14.22 and 14.46, so 0.24v difference. (they are same model Hankook DC24MF, lead acid sealed 80Ah but one is maybe 2 months older. - the 14.22v -)

(packaging is little different too, like stickers and informations layout.)


texts: Can you identify this Bose car amp burned part?

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Many more pictures here

The radio and amp stopped working after a battery jumpstart. I fixed the radio by simply changing a fuse but the amp has a burned part. I tried contacting Bose to no avail. I could buy a full new amp but it feels like it would be easy to fix if I could identify the burned part.

A link to the service manual (which I haven't been able to find) would also be very useful.


texts: Working Principle of AD8232 Instrumentation Amplifier

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Before begin asking, here the datasheet for the IC https://www.analog.com/media/en/technical-documentation/data-sheets/AD8232.pdf

At page 16 under Theory of Operation Section

What I failed to understand is how the Instrumentation Amplifier amplify the ECG signal from electrode. It has an Integrator amplifier with C1 capacitor. As far as I know, integrator will integrate the input. If the input is EKG signal then fed to integrator, doesn't it change the output? I mean we expect the output of Instrumentation Amplifier is just input amplified but still in the same form. But with the presence of integrator amplifier to my understanding it will change the output form which no longer like EKG signal we saw in the input.

Please tell me where I am wrong. I would be happy if someone could explain from the input, GM1, GM2 and integrator working principle. Thank u

Edit===
According to TimWescott's answer I try to derive the transfer function as below

The output Vo still depends on integral of the Vekg