texts: I'm on a job where some folks are attempting to use aluminum plates to separate weld power cables from ethernet/serial comm. To be clear, it's just wires in a cable tray separated by an aluminum plate. Not fully enclosed. Based on the relative permeability of Aluminum, I believe this to be a worthless idea, unless a full Faraday cage is made. Am I correct in believing we would need to use a high permeability material to be an effective shield?


texts: Buck Converter dies unpredictably upon connecting power

texts:
I made a PCB for an ESP32-based solenoid controller that is powered by a 24V DC Jack. I'm using an AP63205 Buck Converter to step that input down to 5V DC, and then a linear 3V3 LDO to power the ESP32. I have assembled multiple such identical PCBs, and they all need to be powered by 24V DC.

The voltage rating of the Buck Converter is up to 32 VDC, and all components around the converter are rated for at least 32V. When I plug 12V into the DC Jack, everything works and the power LED I have on board lights up.

However when I plug 24V, sometimes the boards works normally, but sometimes the buck converter IC will fry itself (only upon this initial plug-in of of the DC jack), shorting 5V to GND (verified that IC is damaged by removing it, and short from 5V to GND on PCB disappears). When this happens, the power LED turns off.

If I power the PCB with a DC Power supply starting at 12V, and slowly cranking up the voltage to 24V, the board always works as expected without frying. I suspect the issue to be related to plugging in the 24V DC Jack, but I'm not certain what could be causing the inconsistent deaths.

Even when the Buck IC dies, the 3V3 LDO still functions and USB powers the board properly.

My buck converter schematic is below:

EDIT: The components I used from DigiKey:

C7; 4.7uF (I used 4.7uF because I didn't have 10uF laying around)
C6; 100nF
C8,9; 22uF
L1; 4.7uH
D5,6,7; Schottky

The 24V DC Power Supply I'm using is the following:

Is it possible that the inductor is not being powered properly upon the initial plug-in of power, causing a large back EMF that fries the IC? Is there any protection against this?

I noticed upon plugging the 24V DC Jack into other devices that sometimes there is a small spark. I'm not sure if that's an issue with the 24V Jack or if that's common, but that's very probably the culprit. I would still like to protect against this.


texts: Connecting multipliers to increase operation bit width

texts: I successfully created a 2 bit digital multiplier. Can I use that 2 bit multiplier to create a 4 bit multiplier and then use that to create an 8 bit multiplier and so on? What I basically mean to ask is, is there a prototype functional block/cell for multipliers, whose repetition while following a certain pattern can help me increase its operation width. Like a one bit full adder cell when cascaded 64 times can help me create a 64 bit adder. Is something similar possible using multipliers or should I directly dive headfirst into the gate level of design?


texts:
I was advised to use RS485 since I have about 7 devices needing to talk to each other (and cannot get CAN to work).

Although I want to start simple (two devices where one sends and other receives), later there might be multiple senders. One of the can be seen as Master, but others also should be able to initiate messages. So I need some kind of polling protocol.

The problem is, in RS-485 every time a device sends a message, all devices will 'hear' it and have to process it (although it's mostly checking one byte to know it's not meant for them).

But if I would get like 100,000 messages per second (worst case), this still cost a lot of processing time. And the master device (who initiates most) needs to do quite some non communication related processing.

How can I reduce the polling? I was thinking of decoupling the master device directly from RS-485 by adding some kind of communication device that passes RS-485 back/forth the master (e.g. via SPI). However, this seems a strange solution (converting back/forth all messages via SPI, also latency will be affected).

Or using some dedicated line (like one of the RS485-A/B lines) that devices can set HIGH to announce they have data. But I'm not sure if I should treat this equally as a RS-485 signal (so essentially having 1.5 RS-485 signals).


texts: Adapting two-way radio tactical throat mic (laryngophone) to cell phone or laptop

texts:
I've ordered one of these: https://www.amazon.com/gp/product/B074Z1LDY2/, a tactical throat mic (and earpiece speaker) which is intended to be used with Kenwood two-way radios (and other compatible models). I'm interested in using this with conventional CTIA TRRS inputs/outputs as found on cell phone and laptops.

I know the pin-outs are incompatible as they are so I know I need to re-wire  at bare minimum. What I'm trying to discover is how to tell if I need some capacitors and resistors or a full, externally powered circuit to support the mic (my primary interest, the speaker is less interesting to me).

I have a mid-level multi-meter and no oscilloscope. I know the pin-outs for these generally:

Kenwood two-way pinouts:

CTIA cell phone TRRS pinouts

How can I best reverse engineer what the two-way radio mic is expecting and how to hook it up to what the cell phone is providing WRT to power? I've not been able to find any references on Kenwood two-way radio mics. Any tips for strategy to make this work, particularly not requiring more specialized testing equipment, would be very helpful. Also, any warnings and strategies for not damaging equipment would also be helpful. ;-)

[Edit: I've come across this which is basically the opposite of what I'm interested in doing but may give helpful context to someone with more insight that I have. http://www.n1gy.com/headset-adaptor-for-kenwood--baofeng-and-wouxun-hts.html ]

Follow-up:

Works perfectly as described by @JRE below. The 3.5mm pin plugs directly into the breadboard jack on the right; the 2.5mm pin plugs into a 2.5->3.5mm adapter and then plugs into the jack on the left. The wiring specifics should be discernible via the photo.


texts: What will be the graph of \$g_m\$ Vs \$ V_{gs}\$?

texts:
Drain current in the linear region is given by
\$I_D=k[(V_{gs}-Vt)V_{ds}-.5V_{ds}^{2}]\$.
Now transcoductance \$g_m=\frac{\mathrm{d}I_D}{\mathrm{d}V_{gs}}=kV_{ds}\$.so \$g_m\$ should be constant parallel to \$X-axis\$ but no option is given.Is there anythinng i am missing?


texts:
If you look at the old NeXT Computer, two things jump out about the form factor: it's a cube, and it looks really cool. Ditto the original Connection Machine.

If you look at, well, absolutely every other computer produced since then, one thing they all have in common without exception is that they are not cubes. Granted that there is no particular technical advantage to being cubical, I would have expected some manufacturers to do it just for the sake of appearance; manufacturers certainly do plenty of other things to make their products look cool.

Is there any technical disadvantage of the cube shape that would account for it being universally shunned?


texts: Does an AC electric motor with no load consistently draw its maximum power at full RPM's?

texts:
Say you have a typical bench AC electric motor rated at 180W which has reached its maximum RPM's.
Does the motor always draw 180W when running at full RPM's ? Or does the motor draw less power once its at full RPM's?

Note that no load is applied in this scenario.

If I imagine this in my mind, it makes sense to me that a motor once at full RPM's and under no load, would draw less power as the momentum should be helping it turn, but I'm not sure so I'm checking with the community.


texts:
I'm quite new to the topic but I know about LTI systems, convolution and Laplace transforms as a concept. I also know the meaning of transient and steady state analysis.

I was reading an article on the subject but stuck at some point.

What is meant by the following statement:

  "Step signal, a ramp signal, and periodic signal are for time domain
  analysis. Only an impulse signal is essential for steady-state
  analysis."


texts: How do I solve the current of this circuit with a diode?

texts:
I am trying to calculate the current of the circuit but I am unable to find the correct answer. I was able to solve the same circuit without the diode witch gave me 2mA. I am unsure of what to do with the diode added to the circuit. Here is my circuit.

simulate this circuit – Schematic created using CircuitLab

The diode polarization is direct with a voltage of 0,7V. How do I solve the current of this circuit? Any help would be greatly appreciated.


texts: How can I make an uninterrupted switch from battery to fixed power for a mobile computer?

texts:
I have a computer being powered off a Lipo battery, and I would like the ability to transfer the power supply from the Lipo to a fixed DC source (eg. power supply) without having to turn it off and back on again. The computer draws around 100w at 12-24v.

I considered having a capicticter hold up the voltage for me but to get even .1 sec of runtime I would need a .5F cap which is much too expensive and big.
Can I just connect the 12v power supply and the battery in parallel with diodes on the positive lines?
What are some other options?


texts: Voltage regulator goes to 0 with 100 ohm resistor

texts:
I'm a beginner on voltage regulators so I have started experimenting with them. I bought a LP2950 3.3V 0.1A voltage regulator (https://www.onsemi.com/pub/Collateral/LP2950-D.PDF). I have a real circuit hooked up like this:

I expect to see 3.3 V on my voltage meter but I see 0. If I remove the resistor, I see 3.3 V on my voltage meter, so the regulator seems okay. Moreover, the current through the resistor should be 3.3 / 100 = 0.033 A, which is below 0.1 A.

Do I need capacitors to get this simple setup working? Aren't they just for reducing problems with noise in a proper circuit?


texts: Lower Voltage Methods Other Than Voltage Dividing

texts: I have recently learned that voltage can be lowered using resistors to divide the voltage. This seems simple and easy. Before this I thought I had to use a voltage regulator or a zener diode to lower voltage. Is there any reason not to just use resistors? What is the benefit to these other methods? Other than the methods I listed, what other ways are there to lower voltage?


texts: VHDL: How to change the resolution of time printed using "now" in VHDL to file or terminal

texts: The "now" is usually used if one wants to print simulation time to screen or into a file. I need to print simulation time in ms into a file. However, using now with writeline into a file is giving me time in ns resolution.


texts: Why is my self built LiFePO4 battery pack not charging?

texts:
[NOTE]
I understand that the adapter that I bought for my battery pack is not actually a charger. I also understand that it could be dangerous what I'm doing. I still wonder why there is no current flowing from the adapter towards the battery pack though. If anybody could help me find an answer to that question I'd be very grateful.
[/NOTE]

I'm building an autonomous boat, and for this I was using this 12V Li-ion battery pack which came with a very simple charger:

This works great, but since I'll need a very specific form of battery (long and thin to fit in my boat) I decided I need to built my own battery pack. From this other project I got the idea that if I use an 18V solar panel I can build a 5S LiFePo4 battery pack which means I will not need a solar charge controller. His reasoning is as follows:

  The behavior of a solar panel connected directly to a battery is similar to your typical CC-CV lithium battery charger: a lot of current until the battery gets close to fully charged, and then the voltage rises while the current decreases (the solar panel will put out less current as the voltage rises).  TO put numbers to this, the Renogy solar panel's max power voltage is 17.7 volts (depending on temperature) and the 5-cell LiFePo4 battery's nominal voltage is 16 volts and its fully-charged voltage is 18 volts.

By not needing a charge controller I would save on complexity, money and most importantly: space in the boat. So if possible I would like to avoid using a charge controller.

So I bought 10 of these LiFePO4 18650 batteries and this 5S balancing BMS and hooked it up in this 5S2P test setup:

Since I don't have the solar panels yet I bought this simple 18V 2A charger:

The batteries came all charged at exactly 3.33V. So after soldering together my battery pack I attached it to my boat. It worked and I left it on for a while. When I came back to it after about an hour the boat shut down. I checked the battery cells and their voltage was 2.8V (way too low). I then attached it to the charger and let it charge for a day or so. When I came back to test it, the battery didn't seem to have charged at all though. It was only charged up to 2.85V per cell.

I then attached a watt meter between the charger and the battery pack, and that showed me an input voltage from the charger of 18.3V, but no current flowing:

This explains why the battery isn't charged, but I wonder why this is happening? The only reason I can think of is that the BMS is blocking any incoming current, either because the voltage supplied by the charger is too high OR because the battery voltage is too low. I checked out the specs of the BMS (pasted below) and in there it says the "Single Overcharge Protection Voltage" is 3.75V, which means the supplied 3.66V (18.3V / 5) from the charger is within limits, but very close.

Am I right in my thinking that the voltage of the charger is too high? And if the voltage is too high, would it work if I simply reduce it by for example 1V? Or can I built in some kind of thing that caps the voltage at 18V or 17.5V or something?

Again; I understand I need a proper charger instead of this adapter. But I would like to understand the reason why there is no current flowing. Would anybody know how I can test/debug this? All tips are welcome!


texts:
I'm currently reading introduction to PRU

And I paid attention to this sentence:

  fast IO -- Many of the pins have special IO modes for direct access by
  the PRU. These work much faster than memory-mapped IO from the main
  processor.

Why is direct access to pins by the PRU, so much faster than memory-mapped IO way?


texts: Internal and external clock synchronisation in FPGA

texts:
My FPGA has an internal clock of 66.66 Mhz. An input is a video signal clocked at the same frequency.

It seems that I can't clock a process processing the data with the internal clock, as I don't know about the phase of the signal, and the two frequencies may not be exactly the same.

I know that I can use a DPRAM to clock the video signal at the internal clock. I have also read that I can use two D latches to synchronise the two clock, but I don't get how it works.

I can't use the external clock because it can't be sure it will always be on.

Then, how can I process external data?


texts: Is there a technical reason not to use RCA jacks for speaker connections?

texts: I'm designing a home-made amplifier and am trying to choose connection options for the speaker outputs; is there any reason that RCA plugs are inappropriate, assuming I control the full system, including making the correct cables? Can they cause interference of some sort? They would be more compact than banana sockets or terminal connectors, but seem rare - is this purely convention or is there a motivating technical factor?


texts:
I am reading this material for understanding the switch mode push pull power supplies.
Push Pull Switched Mode Power Supplies

I am unable to understand the working though. Can someone provide a simple explanation for the circuit in 3.4.2 and its waveforms?

And it is mentioned as R3 and C2 are the timings components which I dont understand also. How do the internal transistors and the external transistors function? Please explain. Thanks.


texts: Connecting LED strip with long cable (10 metres)

texts:
I'm working on a Christmas light display that will feature addressable LED strips on my front lawn. My LED strips operate at 12V (using the UCS1903 chipsetUCS1903 chipset).

The issue is, I need to run a long cable from my Arduino Due and power supply to the strips in some places (approx. 10 metres at the worst case). At this distance, the strips light up but the lights don't change colour. I might be able to reduce the cable length by a couple of metres, but I see the same results at a length of 6m. I'm using this 3-core 1mm diameter electrical cable.

The 3.3v output from my Arduino is below what is recommended for the UCS1903, but I've also tried on a 5V Arduino without success.

My question is, what do I need to look at to achieve this distance? Is it a matter of upping the data voltage, or using a larger cable, or some other technique?

Also, a basic diagram to illustrate my setup:


texts: Will radar/lidar still work when every car is equipped with them?

texts:
Self driving cars rely on cameras, radar, and lidar to recognize the environment around them.  Cameras of course don't interfere with each other, since they are passive sensors.  Since a signal received directly from another transmitter is much stronger than a reflected signal from your own transmitter, what stops the transmitted signals from one radar/lidar interfering with the receiver of another?

Will radar/lidar still work when all cars are equipped with them?  Assuming that they will, how will this be accomplished?


texts: How does wire bundling with the same AWG work?

texts:
I have a PC PSU opened up. The yellow wires are 20AWG, 12V.
According to the AWG table, a single 20AWG wire can deliver 1,5A Max on power transmission, so if I were to power up a device that needs 2.5A, I would need to bundle 2 of those yellow wires together so I can deliever 3A (over my device max draw) on the socket.

Am I understanding this correctly?


texts: In which direction do electric signals flow?

texts:
We know that electrons move from the negative to positive terminal, and that holes flow in the conventional direction of current - from the positive to negative terminal.
I've always assumed that this means that electric signals travel in the conventional current direction and that it's the travel of holes that gets close to the speed of light. Upon further research I come across mentions of electric signals being the electromagnetic waves traveling through the medium by the excitation of the electrons.
This begs the question. If electric signals are the propagation of EM waves at close to c in which direction do these waves travel? In the conventional direction? In the direction of electron flow? In both directions?
I can easily imagine that the signal is directionless and propagates from the point of contact/source of signaling in all directions like light in a dark room. But I'm not sure.

Clarification

Note: This merely presents an experiment to perhaps clarify the intent of the question above. I'd accept answers that don't address this part of the question. Note that you can treat this as a thought experiment but I think it's possible to physically set up this circuit. The only problem is we'd have to deal with resistance in the real world.

Consider a circuit that has 3km of conductors. We start with a DC source attached to 1km of conductor. For simplicity you can assume that the conductor has zero resistance. We attach an LED at the end of the conductor. Then we complete the circuit with 2km of conductor back to the DC source:
                1km of wire
        ┌─────────────────────────────────[resistor]─(LED)───┐
        │                                                    │
         ╱ switch                                            │
        │                                                    │
[DC voltage source]                                          │
        └────────────────────────────────────────────────────┘
                      2km of wire

Assume the wires are spooled so that physically the light bulb and the switch are next to each other.
If I close the switch would I expect the LED to turn on roughly 3.34 us later (the time it takes light to travel 1km) or 6.68 us later or somewhere in between?
Does it make a difference if the 1km line is attached to the positive or negative terminal?
Does it make a difference if the wires are not spooled but are physically laid out over the 1.5km distance? Does the physical geometry make a difference eg. a circle vs a straight line and back?


texts: How to implement a lowpass filter for this one zero, one pole transfer function?

texts:
I have a task where I need to implement a filter circuit (active) for the following transfer function:

$$G(s)=\frac{(s-5447)}{(s-961.3)}$$

So, we have one pole and one zero. The bode plot is as below (dB/Hz):

However, I can't for the life of me seem to design a circuit to implement it. A simple RC filter doesn't have any zeroes, and everything else I've tried (such as the circuit on page 12 of this document) leaves me stuck with terms involving negative real values or \$-\frac{1}{s}\$ which don't map to a real component. (My reasoning is that resistors contain positive real components, inductors \$sL\$ and capacitors \$\frac{1}{sC}\$.

I'm not sure if I'm just solving this kind of equation incorrectly, or if I'm using "bad" topologies to approach this specific transfer function. How would you go about implementing it? Using op-amps is completely fine.

(For context, my circuit needs to reverse the effect of an unknown, "black box" filter. I got my gain function by figuring out the black box's transfer function and inverting it.)


texts:
I was reading one of your previous answers related with grounding of a cable. (Which was Suggesting whether cables should be grounded from both end or single end.)

I was wondering if you can think of a reason whether the type conducting material used for shielding has any effect on signals? Would it matter what kind of material you are using if you are doing single end grounding rather than both end?


texts: What motors or other actuators are commonly used for force feedback?

texts: I'm building a musical instrument with a hinge and I'd like it to resist opening and closing by the user, sort of like a force-feedback steering wheel. Ideally the amount of feedback would be electronically controlled. What sort of motors get used to apply torque that won't burn out if they don't turn? Are there alternatives to motors?


texts:
How can I make a capacitive wall touch switch? remembering that the wall standard light switch has just two wires for close the circuit. How can I supply my circuit when the light is on in order to turn it off again?.

PD: I have designed a capacitive touch switch circuit, but it needs an power supply, a wall outlet for example, but is useless in the case exposed before.

simulate this circuit – Schematic created using CircuitLab


texts: Do antistatic bags have conductive interior, exterior or both?

texts:
From Wikipedia:

  To create the anti-static effect, the black or silver bags are slightly conductive

and

  A device should not be powered while in an antistatic bag, because the conductivity of the bag could cause damaging short-circuits between parts of the device.

So I deduce that those bags are conductive in the interior surface. What about the exterior surface?


texts: Circuit to Convert Line Level to Mic Level

texts: How would I design a circuit that converts a line level signal to be able to be fed into a microphone input? The input impedance of the microphone jack is 2 kohms.


texts: Help to join 3 resistors in parallel into 1 (power equation?)

texts:
I want to join 3 resistors connected in parallel into one. Like this

If for the total resistance I use

$$R_t = \frac{R}{3}$$

But what about the power of them?


texts: dsPIC chips running at a fraction of normal speed

texts:
I have two PCBs. One has a dsPIC30F6012a, the other a dsPIC30F6015. Both are being programmed from separate standalone HEX projects in MPLAB X, using a PICkit 3. Both firmwares have been applied to dozens of units prior to this point without difficulty. Presently, the firmware is operating correctly when programmed from all PCs but one. On that one PC, starting yesterday, both firmwares program without obvious error, but execute at approximately 1/20 normal speed. Prior to yesterday, that PC also programmed these boards without problem.

Splash screens take two minutes instead of five seconds, lights blink very slowly, and yet besides this everything operates correctly. It's almost as if the oscillator configuration bits have been altered, but I'm not aware of anywhere in MPLAB X that can be done to a standalone project.

So two different firmwares, on two different chips, on multiple instances of the same PCB design, running at different speeds depending only on the PC being used to program them. Reprogramming a slow board on a "good" PC fixes the problem; re-reprogramming that same board on the "bad" PC brings it back. All I can figure is that on that one PC someone hit the "make it go slowly" button, but I can't find anything labeled that. (Our techs are pretty creative, though.) I'm presently uninstalling MPLAB X, wiping the user settings, and reinstalling a more recent version. (Going from 1.3 to 1.6.) But even if that fixes it, I'm still not happy not knowing what's going on. Does anyone have any insight into this problem?


texts: Why don't single row circuits work on a breadboard?

texts: I am fairly new to electronics, and whilst messing around with a simple LED circuit on my breadboard I noticed that when connect my resistor and LED on two separate rows, the LED lights up as it expected. However when I connect them on the same row, the LED doesn't light up. I tired this other rows and checked all the connections to see if there was a problem. Can someone please explain to me why the LED doesn't light up when I try to connect everything up on the same row?


texts: 0-10V control signal for valve actuator from -10/10V DAC

texts:
I'm trying to control a valve actuator (24VAC power) that uses a 0-10V voltage input signal which only uses one wire, with a USB multifunction board which has a +-10V DAC control output which uses two wires, "DAC0" and "DAC0 Return". Note that I am only using the "DAC0" line since the device only has one input line. The valve actuator input impedance is 100K ohms, and the DAC can output +-2mA at <0.2ohm impedance. I'm thinking that this should work, but it doesn't. I've also tried an eternally powered 0-10V isolation module, which does generate the desired signal voltage corresponding to my DAC output signal voltage, but this still does not control the actuator properly.
Any ideas? It's definitely possible that the actuator is not functioning properly, since it's pre-owned.
VA7800 Valve Actuator Spec Sheet:
https://cgproducts.johnsoncontrols.com/MET_PDF/12011474.pdf
DT9812-10V Multifunction Board Spec Sheet:
https://pim-resources.coleparmer.com/instruction-manual/18801-20-25-30um.pdf][1] - page 161


texts: Digital Signal Cables Penetrating a RF Shielded Room

texts:
Disclaimer:  I'm not a trained electrical engineer...I'm a recent Computer Science grad with about ten years experience as a RF test tech. I don't know everything, and to me, experience reigns supreme for practical applications like this.  I'm also the only RF person in my organization.  I'm reaching out for an experienced RF, EMI, or EMC specialist to chime in on this issue.

I have a wireless shielded room which doubles as an office constructed of 16 gauge welded steel used for isolating emissions within it from the outside world.  It hasn't been maintained well and there have been several improper electrical penetrations of the shield in the last couple of decades. As the new RF engineer, I'm trying to restore the shielded effectiveness (SE) for electrical field and plane wave attenuation of at least 60dBm up to 10GHz.  We'll have an SE test done after the repairs are complete.

I've made several repairs, including designing and installing waveguide-below-cutoff (WBC) penetrations for fiber and getting rid of ethernet and coax cables.  I've properly filtered all of the POTS phone lines, made some repairs to the finger stock & knife edge doors, patched holes, checked the honeycomb filters, and treated several areas for corrosion/rust.

Here's the last remaining issue...

The room has digital control lines for HVAC thermostats (Metasys N2, RS485, shielded twisted pair) going through the "dirty side" of the filter enclosures and penetrating through a small 3/8" hole in 16 gauge steel to the "clean side" of the filter enclosure.  I'm not allowed to remove the lines.  I have two options that I can see:  convert to fiber and pass through a WBC or bond the cable shield to the steel enclosure. Electrically filtering the digital cables, from what I think I understand, would be problematic because it would filter out the high-frequency components in the digital signals.  Please correct me if I'm wrong there.  Converting to fiber is difficult due to a lack of AC outlets for the fiber converters on both sides of the shielded room.

I think I want to bond the cable shield to the steel enclosure and stuff the 3/8" hole around the cable with steel or copper wool.  Do you experienced folks think that this will be "good enough" to achieve the shielded effectiveness of >60dBm for electrical field and plane wave attenuation up to 10GHz?


texts: Does a firmware (flash memory) in atmel mcus change on runtime (to store variables for example)?

texts:
EDIT: I am purposely trying to corrupt my ATxmega32E5 flash memory.
I am disabling my BOD level on my ATxmega32E5 and checking how it affects my MCU by switching the power on the mcu on and off with a big capacitor attached to it to reduce fall, rise times of the voltage.

simulate this circuit – Schematic created using CircuitLab
I managed to corrupt my flash memory several times (I know that because the mcu lights up a led when turned on, and the led stops turning on at some point). When I re-program my flash, everything works great again, the led blinks.
Now, every time my mcu was corrupted, before re-uploading the flash/firmware again, I stored/read (by using atmel ice) the broken/corrupted flash memory and I can see that it has differences compared to the one I am uploading.
But I wonder, is there any chance that part of these "corruptions" I am seeing, are a normal behavior of the flash memory? Does the mcu change the flash memory in a permanent way while a program runs to store variables for example?
(I know that there are ways to change the flash memory while the mcu is running, but I am not using any of these techniques)


texts: I'm looking at adding multiple USB C ports to a PCB design that all perform the same function (power and data in device most). How can I switch to a port automatically when in use and disable the other ports that are left to prevent the use of more than one port simultaneously? A controller perhaps? thanks


texts: RS485 registers for calculating total power consumption (kwh)

texts:
I have an energy meter (OHIO A2000) which has been now discontinued by the manufacturer. Anyway, I'm following the manual for extracting energy parameters through Modbus RS485 communication. I'm getting most of the parameters accurately (i.e, A, VLL, KW, PF..) but I'm having trouble getting the total kWh value from the attached picture.
How can I get the total kWh value 819371.8 from the Modbus registers?

2018-12-21 13:45:52.367 <02048>     34  32645     49   1399     41 -18381    125  15663     25 -19692     31  20483     39  19877     96  20668

This is the data log from register 0800h-080fh. These are represented as EnergyMeters in the manual. These should be multiplied with 10^2 to get the actual values.(Dim.P = 2). But I'm having trouble in interpreting these values, which entry belongs to what value? Also, I don't see any entry from these values would result in the total kWh (819371.8).


texts:
First post here, it's probably a very easy fix for most of you here. Right now I'm trying to use a digital potentiometer in a voltage divider to step down a voltage from 5v to a range of 3 - 1.5 volts that will go into a set of 4 DC vibrational motors. The resistance of the digipot is in the range 10Kohm - 1Kohm while the motors are only about 15ohms.

In order to supply enough current I put a voltage buffer in front of the motor however that still doesn't fix my problem. I'm able to control the output voltage of the buffer well without the motor attached in the 3 - 1.5 volt range however as soon as I plug in the motor the voltage drops to 0.420 V (according to an oscilloscope).

I'm using a UA741 for my op amp and TIP120 as well in the circuit. Power is being supplied from a simple DC power supply, I plan to eventually use a battery to supply power. I've attached a drawing of the schematic and links to the data sheets below.

TIP120 NPN Transistor:http://www.bc-robotics.com/datasheets/Tip-120.pdf

UA741 OP amp: http://www.ti.com/lit/ds/symlink/ua741.pdf

Motor: http://www.nfpmotor.com/spec/encapsulated-and-enclosed-vibration-motors/Encapsulated-vibration-motor-NFP-E0724.pdf


texts: What is an efficient way to divide clock by 1000 or more?

texts:
Context: This is a home brew project that incorporates NO microcontrollers as a learning exercise. I need to time something up to 20 seconds long, down to the nearest 100th of a second, and display the time interval measured. I'm using a 4 digit 7 segment common cathode led for the display.

I have a 100khz crystal and I want to display the tens, ones, tenths, and one hundredths of seconds (ie 23.36 seconds) on a 4 digit 7 segment led display. I thought I could use the 4026 chip, a decimal counter and led driver. However I have to chain 3 of them just to get to 100hz, then chain another 4 of them to get the 4 digits of display. 7 ICs (plus multiplexing logic because the display uses common abcdefg leads, plus resetting etc) seems like a LOT.

Am I missing a much simpler way to approach this? The 'rules' are: any ICs or other components but no software (no MCUs).

Thank you.


texts: Effect of a capacitive or inductive divider on noise

texts:
I am used to thinking about the effect of an attenuator on a system's noise in the following way:

there is some system noise (and signal) at the attenuator's input, coming from the preceding part of the circuit
this system noise is attenuated by the attenuator by the same amount as the signal
the attenuator is resistive, so it adds some noise power at its output as a function of its temperature

I can then calculate the noise power at the attenuator's output as the total of the attenuated system noise and the attenuator's Johnson noise. The signal to noise ratio is the ratio of the attenuated signal power to this noise power total.
I wondered, can I cheat this by using a perfect capacitive (or inductive) divider instead? These idealized components do not create Johnson noise, so do I win on the signal to noise ratio that I acquire at the output of my attenuator, compared to the resistive case? If so, why would I not always do this, instead of using resistive attenuators?
This answer implies that I cannot do this: a capactive divider will still increase the noise in the system. It mentions statistical fluctuations in the division of currents between the signal path and ground as the reason.
Could you help me understand this, or provide some more detail on the physical processes here?


texts:
I would like to give you all some premise before asking this question. I am a highschool student from India and I generally do software development, so this is one of my first hardware related projects so I am a complete noob at this stuff.

Our team had been tasked with construction of a mini war robot for a competition. We thought that the best way to go about it would be with 4 powerful motors with PWM controlled wirelessly via bluetooth using an Arduino. I was successfully able to figure out the code and created the controller.

The problem we are now facing is what would be the most efficient and low cost way to power our 4 motors and what batteries should we buy.

The motors that we have used are 200 RPM Johnson Gear DC Motors 12V with maximum load current upto 7.5A We were also considering buying these motor drivers which I Linked here https://robokits.co.in/motor-drives/dual-dc-motor-driver-20a

My Question is what battery should we use so that the robot runs with full power for at least 30-45 mins and should we use two dual channel motor drivers(one for each motor) or one motor driver(two connected in parallel with one motor driver)

(not sure if this should be here or in robotics stack exchange figured this was a more electrical engineering question)


texts: Convert gadget from Solar charging to wired charging

texts:
I have one of these ultrasonic pest repellants.
https://www.amazon.com/gp/product/B08GLYYL92
The gadget is powered by solar power but I live in an area that does not receive enough sunlight to power the thing well. I was thinking to convert the repellant from solar power to a wired DC input to charge the battery pack.
If there is already a controller in place charging the battery pack from the solar cell, is it as simple as wiring in a port to plug in USB? Can anyone point me in the right direction to accomplish this?
Thanks!


texts:
This is a short question but a seemingly important one.

Is it possible for a multi-master i2c bus to have two masters send the start byte at almost exactly the same time?

If so, what would happen?


texts:
This datasheet (see page 22) has the dimensions of its diagrams in "INCH/(MILLIMETER)".

What does INCH/(MILLIMETER) mean? Is it a unit of length? (I would expect it to be unitless, given length/length is unitless.) If it is a unit of length, what is 1 INCH/(MILLIMETER) in millimeters?


texts:
https://www.vishay.com/docs/83741/83741.pdf example 2

I have existing H22A2 optocouplers that I am trying to run 12vdc through to get a plc input to turn on and off. I am using a 1k resistor on the 5vdc LED. I am using a 2.7k resistor on the OPTOTRANSISTOR side with the 12vdc. I can get the input to turn on and off, but the voltage drop is so minimal that it is way to sensitive to be consistent. Any ideas?

plc model from automation direct BX-DM1E-18ED13 specs https://cdn.automationdirect.com/static/specs/bxdm1e_18ed13.pdf

H22A2 datasheet https://media.digikey.com/pdf/Data%20Sheets/Fairchild%20PDFs/H22A1,2,3.pdf

I will have 4 of the optos going to 4 separate inputs.

'>9.0vdc ON  <2.0vdc OFF for inputs

simulate this circuit – Schematic created using CircuitLab


texts: Arduino - accessing extra analog pins on 32-pin SMT package

texts:
I've got a 32-pin ATMega328 on a breadboard. I have its analog pin #6 as an input pin from another IC on my board. The IC sends data to this analog pin.

Now, the ATMega328 DIP package (used on the Uno, and other default arduino boards), has 28 pins (instead of 32), and only 6 analog pins (numbered 0-5) total.

I don't get any complaints from the compiler, and am able to upload code successfully to the arduino.

I bootloaded the board using optiloader.

Problem

Using my scope, I expect to see signals coming from the IC, but I just see a flat-line signal. My guess is that, by choosing 'Arduino Uno' as my board from within the Arduino IDE, the code dealing with setting up the analog pin 6 is ignored, because the compiler assumes there is no analog pin 6 on this board. Therefore, the analog pin is automatically just pulled down to zero, and any variations in voltage coming from the IC output pin are brought down to 0 by virtue of being connected to analog pin 6.

Attempted Solution

I tried switching the board I use from the Uno to the Nano (with ATMega328), since the Nano actually runs on the same 32-pin SMT package I'm using.

But now I can't get even the most basic sketch to upload to the board. I tried selecting a few other boards from the menu in the Arduino IDE, and am unable to upload code using any selection besides the Uno.

I'll keep hacking away and researching. Any solutions popping out?


texts: How to export .TOL and .DRI files in ALTIUM designer 16

texts:
Is possible to generate this files? my PCB provider asked it to me but I can't find them in gerber exportation tool.
Thanks


texts:
How LNB can transmitted data to receiver in dc voltage,
I measure the voltage which is out of the receiver and a found it dc signal

My question is how the receiving signal gets to the receiver back in dc voltage?


texts: RMS value of a line to neutral voltage on a three phase inverter

texts:
Basically, I feel like this is an incredibly simple thing, but my brain is stuck on it for hours now, and I can't find the answer anywhere.

How do I find the RMS value of the signal shown, assuming all of the "steps" are of the equal duration? Do I have to do an integral from zero to T (but then what would the function inside look like?) like usual, because it really feels like there's some incredibly simple thing I'm missing here?

I should also write what I tried, but it doesn't seem right at all:

$$Ua0rms=\sqrt\frac{{((\frac{Uo}{3})^2+(\frac{2Uo}{3})^2+(\frac{Uo}{3})^2)*\frac{T}{6}}}{T}$$


texts: Nodal analysis with Laplace of simple circuit

texts:
Using nodal analysis with Laplace transform find “v” for “t > 0”

Founded initial conditions:

i(0-)=i(0+)=0A

v(0-)=v(0+)=0V

i(infinite)=3A

v(infinite)=4*3A=12V

My nodal analysis with Laplace transform equations are:

v1 – node where current source flows into circuit

The Laplace of “v” is in the second row, but it seems to be an error in my equations – the answer in book isn’t equal to reverse transform of second row! May anyone help to properly write that equations?


texts:
I'm testing a load cell where the result drifts over time.

By weighing it down with a known weight over night, the result crept up by 10% in 18 hours. It's a completely linear increase, with consistent variations due to noise.

I'm using a HBM QuantumX MX840B and two pairs of strain gauges that form a full bridge. The cable has been perfectly still during the test. The strain gauges are 120 ohm and it's been set at a 5V exitation voltage. The load cell is of stainless steel and is quite massive, so I would assume heat dissipation shouldn't be too big of an issue, but I don't know.

Temperature is reasonably stable (it's indoor) and the full wheatstrone bridge would compensate for change, something we also tested with a heat gun.

I'll re-mount the strain gauges on the load cell and see if it gets better, but I'm not sure as to why it drifts, and especially in such a linear way, and advice would be helpful.

Edit: This is what I'm going to do in order to re-mount it properly, please give me input as to where your experience differs from this.

Physical installation of strain gauge:

Remove all strain gauges
Clean with isopropanol
Prepare the area with rough grinder if need be
Sand down to 320 grit with electric sander or grinder flappy disks
Slightly roughen the texture with a courser paper to increase adhesion
Clean with isopropanol again Put a small amount of HBM Z70 cyanoacrylate glue
Push the strain gauge down with my thumb Cover with suitable material (silicone or similar)

Results from load cell overnight testing:

This is from testing the first cell over night, it dips considerably.

This is from the second cell, it has a much smaller variation. It makes a huge dip in the morning, something we have seen before. This is because the test lab has eight huge halogen lamps in the ceiling that draws a big current when starting, I'm certain those affect the results. What is concerning is that it does not recover back to it's previous state.


texts: NI-MH battery monitor design. Any obvious errors?

texts:
Let me preface this by saying I'm not that much of an EE expert, this is a "hobby" project, I consider myself as knowing enough to be dangerous. ;)  I'd never apply for a full time career as an EE designer, that's for sure.

That said, I saw this: Low Current Battery Monitor Detail Question and this: Low current battery monitoring in regard to battery monitoring, but they don't address the situation I have.

In my case, I have a 6 cell NI-MH battery that is either not attached to the circuit at all, or it's attached and under load.  I'm using a battery pack designed for an RC car, and to turn it off, I just disconnect it.  However, I want a monitor that will indicate when the voltage drops below about 6V, since that's the point at which I want to consider the battery pack as discharged.

My current design is the following:

Please accept my apologies for the somewhat low quality circuit diagram, there's limits to what I can manage with a generic paint program.

The TI TL7757 is intended to assert /Reset if it's VCC drops below 4.55V, data sheet is here:

http://www.ti.com/lit/ds/symlink/tl7757.pdf

The Bivar 3BC-C-CA-F is a common anode two color LED, data sheet is here:

http://www.farnell.com/datasheets/1756451.pdf

My logic is that the 470 ohm pot will allow me to adjust the voltage on VCC of the TL7757 so that when the battery hits 6V, the TL7757 sees 4.55V.

Above that voltage, /Reset is high, it's an Open Collector output so the Red LED is off, however the leakage through it, the 270 Ohm resistor and the 100K resistor should be enough to turn on the 2N-3904, which in turn illuminates the green LED.

When /Reset drops, current flows though the red LED and the 270 Ohm resistor and the TL7757, illuminating the red LED, the voltage on the base of the 2N-3904 drops, turning it off and with it the green LED.

Have I made any mistakes that might stop this from working as intended?


texts: I am rewiring a cheap old organ for digital and want to use shift registers to read all the keys. Is it possible to debounce the keys after the shift registers, or do I need to do it before? Either way, is there anything I need to keep in mind?


texts: AC coupling capacitor in the ground to break the ground loop?

texts:
I'm implementing the following audio single-ended to differential converter for an ADC:

This is the reference design for the PCM1804 that I intend to use.

What would happen if I do this:

Would it still work?

The reason I'm interested in doing this is demonstrated in the following diagram:

simulate this circuit – Schematic created using CircuitLab

Even though I'm using an isolated power supply for my DSP, my amplifier internally connects the signal ground to the chassis. There's clearly a huge ground loop, consisting of the ground shield in the RCA cables and the car chassis that is a big source of noise.

I thought inserting a capacitor in the way of the ground as shown above would break this ground loop. But apparently, this is not a good idea. Any other suggestions are much appreciated.

I am aware of ground loop isolator transformers, but that's a band-aid fix, and they create a large amount of distortion.


texts: How to eliminate noise from switched power supply

texts:
I have an isolated switching power supply (120v in, 12v out) that gives an output shown in Figure 1 when referenced to the output ground (I'm not TOO worried about that noise). The bigger issue I have is the noise I have when referencing the output voltage to the input ground shown in Figure 2. To me it looks like the differential mode noise is acceptable but there is a ton of common mode noise but I am not 100% sure how to go about fixing this. I read a lot about common mode chokes but I am not exactly sure how to choose the correct one.

EDIT:
So to give the full story to clearify. I have a touchscreen that is picking up random touches only when powered by the power supply described. I have already tried full power and signal isolation and power regulation which was able to get rid of nearly all differential noise. The only noise still getting through is all common-mode.

Also, I only have the option to fix this issue on the touchscreen circuitry with no ability to alter the power supply. A simple fix would be to bridge the input and output grounds with either a jumper or cap but unfortunatly, this cannot be done.

                          Figure 1

                          Figure 2


texts: I am failing z-parameters, but I don't know why

texts:
I need your help to see where am going wrong.

A two port network driven at both ports such that the port voltages and currents have the following values:

\$Z_0\$ = 50 ohm
\$V_1\$ = 10 < 90 - degrees
\$I_1\$ = 0.2 < 90
\$V_2\$ = 8 < 0
\$I_2\$ = 0.15 < -90

Determine input impedance seen at each port, and find the incident and reflected voltages at each port.

I got:

$$Z_{12} = \frac{-V_1}{I_1} = \frac{-10 < 90}{0.16 < -90} = 62.5$$

and

$$Z_{21} = \frac{-V_2}{I_1} = \frac{-8}{0.2 < 90} = 40 <- 90$$

But they say \$Z_{12}\$ and \$Z_{21}\$ should be equal. What am I doing wrong?

(Original image for question here.)


texts:
I am curious about this schematic (I would develop a project around this machine)
I was trying to understand how this bass drum work, but sounds complicated for me...

The trigger input is a pulse.

So : I already get some stuff :

I think there is a bridged T network filter around the First OA : C41/C42 + R166 and Q43.
I guess Q43 is for starting oscillator ?

I am actually trying to get the transfert function of this simplified part of the schem :

simulate this circuit – Schematic created using CircuitLab

I think i can simplified the schem by that, but I can't find the transfert function !
(I don't know exactly how to start..., also because I don't know what s will be the load, after the OA.

Thanks for you re help, have a nice day !
Vivien


texts: DS3231 on Battery Power and Use of Aging Register

texts:
Currently working with  DS3231M RTC module with Arduino Uno and also creating a library for this. It is working perfectly but I have a doubt that DS3231M work on both VCC(main current) and VBAT (i.e the battery). So when I switch off the power from VCC it is not possible to communicate from microcontroller to the DS3231M through I2C just want to know why it is happening, is it the normal behaviour of the chip or I am doing something wrong?

Also if anyone can please explain the use of Aging Register in the chip and how it can be helpful to adjust time. Here is the data sheet DS3231M Datasheet. But there it is written, " Use of the Aging Offset register is not needed to achieve the accuracy as defined in the Electrical Characteristics tables."

Thanks to all in advance.


texts:
I have a 40 mm hole which I shoot through with an air rifle. The diameter of the bullet is 4,5 mm and length is 5 mm. It's speed is max 200 m/s. I calculated that 40 000 samples in a second would be enough. (Which is wrong, 100 000 is right.)

I must detect the bullet when it flies through the hole. I have figured two different systems to do that.

Two parallel mirrors. One on both sides of the hole. A laser beam zigzagging between these mirrors and a light detector.
Here's a picture of it. The small circle which represents the bullet is in scale with the bigger.

The "normal" system which is used in chronographs. It has only a light detector and detects the shadow of the bullet.

I think that the first method would be easier to construct because it would cause a very big change in the light detector. The shadow of the bullet is very small and it would require an amplifier to detect it.

Does somebody have other ideas?


texts: Connecting Geiger Counters in Coincidence

texts:
So for this Geiger Counter kit from mightohm (https://mightyohm.com/blog/products/geiger-counter/), does any one have any suggestions for what circuits to build to connect two detectors in coincidence?
I had contacted the maker, and he had not done it yet, but he suggests a circuit that takes the GM_PULSE and did some signal conditioning and then a logical. The problem is just I don't know what that means. If there are some general circuits that people build to process such signals, I would love to know.


texts:
i am using LM7805 whose output voltage 5V and Output Current 1A
i have used this to feed 5V supply for my application Circuit and
my application circuit draw 125mA current ,
even tho 125mA current is less than the 1000 mA my LM7805 is slightly
heated and application circuit not behave like its original functionality
so what should be the probable issue that my power supply circuit is having do you think and please let me know
and sorry for my poor english !!!
thank you !!!

Problem got solved and  this  issue is because of microcontroller oscillator frequency and after scaling down this frequency problem got solved !!!


texts: how to select the right TVS / fuse combination?

texts:
I am working on a design featuring the MP1495S switching regulator. The regulator will take 12V and output 5V. The maximum current I want to allow at the output of the regulator is 3A.

1) I am correct in thinking that this implies a max current of 1.25A at 12V at the input?

2) I want to protect the input of the regulator using a PTC and a TVS, and need help selecting the correct ones. Would the 0ZCG0260FF2C combined with the  SMBJ12A work?

I looked at the electrical characteristics of 0ZCG0260FF2C but I don't fully understand how the rated voltage relates to the trip and hold current. They mention "rated current", so they probably mean trip current?

EDIT: I realized I probably need a bidirectional TVS so I also protect against reverse voltage, so I should probably use the SMBJ12CA instead?


texts: Switchable High Side and Low Side switch with FPF2700 & BTS3134N

texts:
I have had the bellow circuit designed with the intention of switching the high side of a 12v automotive relay:

Now I've realised I need the option to switch the low side of relays, as sometimes I have no access to the live wiring or can't control it.

However I don't want to add any extra connectors, so I need to have one output pin that switches between high(14v) and low. (I think the correct term would be a half bridge?)

Can I just add a BTS3134N like the following:

The FPF2700 is active low and the BTS3134N seems to be active high so it would be impossible for them to be turned on at the same time.

Or could I use a H bridge IC such as the L6206Q which lets me control both outputs to High, Low and High impedance. But i'm concerned as I'm not sure if it is designed to supply current from both outputs at the same time.


texts: Driving Partly Specified DC Motor With AC/DC Power Supply

texts:
I'm currently doing a hobby project regarding a wood cutting saw. To do so, I have bought a DC motor from a local seller. The seller provides this information only:

Voltage: 12-36V
Max Rpm: 15000
No load current with 12V: 1A
No load current with 24V: 1.5A

As a matter of fact, no rated/nominal voltage, current, and power values are available. However, once I researched on the web I found these:

Brand: Mabuchi
Model: RS-775SF
Power: 230W

Then, I bought a 12V/30A power supply (AC-DC transformer mostly used with LED strings) assuming that it could drive my motor up to 30A once I forced it (apply high load by holding the shaft with gloves ). Unfortunatelly it did not, it gives max 4.5A only.
I'm new on electronics and confused very much. I have a lot to ask but the main things are:

First of all, is there any environment on the web to find the offical specifications of DC motors?
What is wrong with my 12V 30A power supply? Isn't it supposed to give much more than 4.5A if loaded?
Which power supply (or any configuration) should I use to drive my DC motor optimally if my design criteria is such: around 10000 rpm with 150W cutting power (1.45 kg*cm torque)?


texts:
If someone could explain how does this circuit operate it would be appreciated.

As far as I can see the "trigger" is a rising edge which is low pass filtered by R10 & C4. I'm not 100% sure about the Q1 & Q4 transistor parts of the circuit. The next part looks like a classic astable multivibrator which chops up the output (?!?) and the last part with an op-amp is a driver for the speaker with some filtering on the output.


texts: Power factor calculation of an offset sine wave across a non-ideal capacitor

texts:
I got into a discussion with another student while we were studying and we couldn't come to a conclusion.

Assume you have a non-ideal capacitor with some ESR and leakage resistance. If you subject that non-ideal capacitor to an offset sine wave (AC voltage signal with a DC offset) and you wanted to calculated the real power, would you:

Multiply the product of the offset RMS values of the offset voltage and current waveforms by cos(phase shift), or
Multiply the product of the RMS values of JUST the AC waveforms (without the DC offset) by cos(phase shift) then add the DC power which you can calculate from knowing the ESR and leakage resistance?


texts:
The circuit below is a PW modulating circuit:

The output of the circuit is:

But when I connect a resitive load to the output of the op-amp. The output vanishes:

Can someone explain why is it happening so?


texts: DC current consumption with sense resistor, different measure on oscilloscope and multimeter

texts:
I'm doing low side current measurement over a 0.1ohm resistance. Load is a DC motor powered with 12V.

Cable length between resitor and power supply ground ~60cm

I get a voltage of :

75mV => 750mA using power supply current info
75 mV => 750mA using multimeter measuring resistance voltage drop
100 mV => 1A using multimeter measuring voltage drop between resistance and ground on power supply (60cm of cable between resistor terminal and power supply GND)
100 mV => 1A using DSO-X 2014A oscilloscope and doing single ended measurement
75 mV => 750mA using DSO-X 2014A oscilloscope and doing differential measurement (using 2 probes and A-B math function)

Here is a scope capture with single ended measurement (average down with lower horizontal sensitivity) :

Measures done :

in single ended measurement (with oscilloscope ground connected to
power supply)
with multimeter when it measures on COM connected to    power supply
ground

shows influence of cable length. Cable is classic cable of 3mm diameter, 60cm length?

How can we precisely explain this difference?


texts:
If the current \$i=0\$ the total energy absorbed is:

\$E_{tot}=E_C+E_L\$, where \$E_C\$ is the energy absorbed by the condenser and \$E_L\$ that absorbed by the inductor.

Now:

\$E_C=\frac{1}{2}C v^2_C(t)=\frac{1}{2} C \Big(\frac{1}{C} \int i\ dt\Big)^2=\frac{1}{2C}(\int i\ dt)^2\$.

Since \$i=0\$, it should be \$0\$ too, but my book says it isn't zero. Why?
\$E_L=\frac{1}{2}L i^2_L(t)=\frac{1}{2} L \cdot 0 =0\$

simulate this circuit – Schematic created using CircuitLab


texts:
The 8086 microprocessor can address up to 1MB of memory (20 bit address bus). Most books show a diagram of this 1MB memory which in turn shows interrupt vector tables, DOS function, BIOS routines taking up memory space etc

MY QUESTION:

When the 1MB of memory is referred to, do the books refer to the ROM and RAM of the computer. Is the ROM + RAM = 1MB of memory interfaced? If yes, when memory mapped I/O is shown as a memory segment in this 1MB memory space.....do they mean that the I/O ports is taking some of the RAM memory?


texts: How do I read the markings on a Mitsuba capacitor?

texts:
I'm trying to identify a suitable replacement capacitor for use in a relay. The relay is by Mitsuba and uses a Mitsuba capacitor, which appears to print different notation on it than I have found in guides or SE questions so far.

My guess is this is a 3uF capacitor based on the markings, which seeks a bit strange given its size (~2cm long by ~1cm in diameter). Here are the markings:

85(degrees) 8 (2) 3U

There is also an encircled "4 " down the side, but not where the printed strip indicating the negative pin is.


texts: Maximum Power Point Tracking for multiple sources

texts:
I know there are several commercial products for maximum power point tracking for a single power source (solar cells for example). But does anyone know any solution for the case where there are several sources? For example, solar combined with piezoelectric generator?
These are two suggested architectures that I can come up with; but the optimal solution may be different from these. Specifically, connecting the sources in series may not be a good idea.

where I have multiple sources (in the figures above two sources) of power and need to have the combined maximum power from each source in the output.


texts:
Suppose you are building a device that needs a small CPU, it's running on battery power so you want to minimize the energy consumption, and you only need a small amount of computation. What's the most energy-efficient CPU?

My first thought would be that an 8-bit CPU would use the least energy. But on thinking about it further, maybe something a bit more powerful would be more efficient. For example, a 6502 has only a few thousand transistors, an ARM-1 has an order of magnitude more - but the ARM-1 delivers more than an order of magnitude more computing power, so it might overall save energy. Is that reasoning correct?


texts: Microcontroller PWM LED strips driver with N-channel MOSFET

texts:
I'm trying to control 12 V or 24 V LED strip (consumption around 5A) with an STM microcontroller. The outputs of the microcontroller are 3.3V PWM.
I'm looking to use the following N-channel MOSFET: PSMN2R8-80BS-1 or FDS6910
I'm a bit worried if the 3.3 V will turn on the MOSFET enough. Because of that, I was thinking to use NPN transistor which will opening the MOSFET with 5 V.
Can you share your opinion which MOSFET to use and if it will work without an additional NPN transistor.
Thank you for your time.


texts: Can a short circuit kill the USB port of a PC?

texts:
I use a cut USB cable as a 5V power supply from my laptop.
If the two wires on the other side happen to touch each other, will it kill my USB port?
Just to be cautious.


texts:
I am wiring a small plastic model with 11 yellow 3V 0402 LEDs. I used the resistance calculator to find I need as many 56ohm resisters attached to each LED in parallel to keep them running properly, but that takes up an awful lot of space in a very thin model.

Is there any way I can keep them powered safely but not need to wire 11 resisters? The website won't show me any other way and I'm not the best at researching this stuff.

Thanks


texts: In an op-amp, why does Vn approach Vp until the difference is delta V / A? Why doesn't Vn just equal Vp?

texts:
In an op-amp (non-inverting),

when \$V_s\$ increases by \$\Delta V\$, \$V_n\$ approaches \$V_p\$ until the difference is \$\Delta V/ A\$ (where A is infinity).

Why is there the \$\Delta V/ A\$ difference and where does this difference come from? Why doesn't \$V_n\$ just equal \$V_p\$ (so that the difference is 0)?


texts: Li-ion charge / discharge circuit with ESP32 and MOSFET

texts:
Here is what I’d like to do: Wire a circuit that can either charge or discharge a single li-ion cell (3.0 to 4.2 V) or just do nothing at all. An ESP32 controls the circuit (max. 3.3 V). An INA219 monitors current and voltage (but that is the least of my issues).
For charging, I am planning to use a TP4056 module which would be permanently connected to a USB power supply. For the discharge, I’ll be using a load resistor and a MOSFET (Q1) as variable load. This N-channel MOSFET also acts as a switch, to turn off the discharging process when pulled to ground. Here is the schematic:

I am pretty sure that the second N-channel MOSFET (Q2) would not work in this configuration. Probably a P-channel would do the job, but that I am not sure of and neither do I know if I can control a P-channel MOSFET by directly connecting it to a GPIO pin of the ESP32.
Now my questions:

Is there a way to change the circuit / place the second N-channel MOSFET so that it would work?
If not, would a P-channel MOSFET work and could I connect it directly to a GPIO pin of the ESP32?

Link to IRLZ44N data sheet:  https://asset.conrad.com/media10/add/160267/c1/-/en/000162877DS01/datenblatt-162877-infineon-technologies-irlz44npbf-mosfet-1-hexfet-110-w-to-220.pdf


texts: Combining multiple bar type load cells to measure large weights

texts: This is my first post here. I want to make a scale that can measure weights up to 60kg. I have three 20kg bar type load cells. I can successfully measure weights with the load cells individually (just up to 20kg of course). Is there a way I can combine the three load cells and aggregate the measurements from each of them so as to get a maximum measurement of 60kg (hysteresis taken into consideration too). Also, what is the optimal way to arrange the load cells so that the weight to be measured will be evenly distributed across the three load cells? I will really appreciate your inputs.


texts: Decreasing manufacturing variance in analogue designs

texts:
I'm designing some modular sensors for my company's internal testing. Most are analogue, with a sensor (PT100, current shunt, pressure transducer etc), some interfacing (REF200 based PT100 circuit for example) and an op-amp (usually an OPA170) to send the 0-10V signal down the wire to the NI based measurement equipment.

I had our first batches of sensors made with 1% resistors, and there's more variance than I'd like on some sensors - for example the PT100 units are +/-3degC over our ten unit prototype run with the same PT100 sensor.

Other than switching to 0.1% resistors, is there anything else I can do to reduce variance between units?

Thanks!


texts:
I’m hoping you can help me as my head is spinning attempting to calculate the run time of a Dometic Fridge on a portable power bank, which I will eventually add solar panels to the system.

Im planning on using a 12v Dometic Fridge CFX 40, and the power bank is the Jackery 500.

The Power bank battery is rated capacity is 518Wh (24Ah, 21.6V), and I will be plugging the fridge in the DC 12V, 10A “Car Plug” of the power bank

According to some youtube videos, once up to temperature the Fridge used 27 Wh and 2 Amps in 4 Hours, averaging 6.75 Wh and 0.5 Amps.

1 – If I calculate via Wh, using the manufacturer formula of (Working time = 518Wh* 0.85 / operating power of your device) = 518 * 0.85 / 6.75  = \~65 Hours
2 – if using a similar formula for AH, battery life = capacity / consumption * (1- discharge safety) = 24Ah / 0.5 * (1-.015) = \~40 Hours

Now I’m guessing my discrepancy is the battery voltage vs the appliance voltage, but which result is correct?

Thanks!


texts:
Most NPN silicon phototransistors that I see (Everlight, Kingbright, etc.) have fairly poor rise and fall times, on the order of 10us.

The best one I've seen so far is the QT Brightek QSD8T120B with rise and fall times of 7 us. Manufacturers always specify these times given certain load current and resistance and collector voltage, and in this case they are 200uA, 100R and 5V respectively. 7us would allow for a best-case data transfer rate of about 71kbit/s.

What is the limiting factor here? Junction capacitance? Is there a different technology for IR detection that I should look for to get theoretical data rates of at least 500kbit/s?


texts:
I have designed a circuit for amplifying a PH probe signal and am unsure what type of ADC to use

I was reading on differential vs single ended ADCs. What is the best to use here? I know differential will give me some noise rejection. If I go this route, what do I use as a reference voltage? I do not understand how the differential signal gets converted to the digital values. Do I supply a reference voltage somewhere in the middle of the upper and lower bounds I expect, and it would use the +-Vdd or +-Vdd/2 as the max/min value??

With a differential ADC, can the difference in voltage between the two input pins be negative and positive? Do I not need to do a DC offset(as is done in the circuit above) to get me into positive voltage?

Can I use a single ended ADC here?


texts: Understanding capacitance in oscilloscope probe tip

texts:
I am trying to understand the capacitance and resistance in oscilloscope probe tip.

In the above attached image, that 9Mohm resistance is used for that 1x and 10x setting that divides the input voltage by 10 times or not, right?

But which capacitance are we referring to when we say that the probe has some capacitance?

Are we referring to the capacitor marked 1 or marked 2?

And second question, how does this capacitance impact while measuring high speed signals?


texts: Shared LED strip data line with multiple power supplies

texts:
I am wanting to drive a long run of addressable LED strips using multiple power supplies to accommodate power requirements.  At no point am I going to connect the positive terminal of each power supply together as I know this will cause problems.  I am however wanting to share a data line between power supply runs (see diagram).

I have wired up this diagram and it appears to be partially working but the second LED strip will glitch out quite frequently (random colours, not in sync with strip 1). This seems to indicate the data signal into the second strip is not very clean.

Is there a way to pass current between power supply 1 and power supply 2 in the way of the data signal that will not be too noisy?


texts:
I am designing a receive signal path for Ultrasonic Transducer.

The circuit needs to measure time of flight of ultrasound wave pulses with frequency of 1MHz(about 16 periods - 16us).

Below is the waveform measured. Yellow is Excitation Pulses to transmitting transducer, and Blue is signal received with receiving transducer.

The problem is that the amplitude of the received signal may change due to transducer spacing, or change in transducer mounting position, temperature, and other various reasons i don't know. And due to mechanical property of the transducer, the received signal amplitude naturally ramps up gradually, then ramps down.

I am thinking of applying Automatic Gain Control Circuit after 1MHz bandpass filter to feed to comparator.

I've looked at few options for AGC, but can't decide how to implement.

Unlike RF signals or sound signal , ultrasonic pulses don't have continuous input level. So, the AGC has to respond fast,  adjusting within 1 period(1us).

1) Will traditional AGC configuration using amplifiers such as MC1350 or MAX9814 work in this particular application? which configuration would you recommend?

I have to keep the output signal of AGC at constant voltage amplitude(if there is signal), with DC offset of 2.5V. The jitter in Time of flight measurement is critical(1ns jitter may result up to 30% error in some application)


texts: Trying to simplify complicated boolean expression

texts:
$$U=(X+\overline{Y}+\overline{W}Z)(WY+Y+\overline{W}Z)$$

I have been trying to simplify the above expression for over an hour and can't figure out how to go about it. The results that I have gotten have been Z and just 1. I'm not using the rules correctly or something. I feel like if someone can get me started on the right track then I can do the rest.

Thanks for any help.

EDIT: After FOIL and simplifying the easy terms I'm left with this:
$$U=XWY+XY+X\overline{W}Z+\overline{Y}\overline{W}Z+\overline{W}ZY+\overline{W}Z$$
Should I take out like terms or is there something else I can use?
Is this allowed:
$$U=X(WY+Y+\overline{W}Z)+\overline{W}Z(\overline{Y}+Y+1)$$Again thanks for any help.


texts: Distortion via Powered Speakers and not in Headphones - 1 Transistor Amplifier

texts:
I'm trying to make this NPN amplifier circuit work for my battery powered computer speakers. This circuit works fine if i connect headphones to it in output, but has distortion when connected to a powered amplifier like computer speakers (which i have connected with a battery).

I tried few values of different R and C, but the distortion doesn't go away, while the sound is clear on headphones.

Is there a way to make this circuit compatible for an amplifier, so that there is no distortion... I understand that the speaker in this amplifier circuit is in series, and maybe that is the reason for the distortion, via the 5v computer speakers.

simulate this circuit – Schematic created using CircuitLab

Here is the Falstad Simulation Code:

$ 1 0.000005 6.450009306485578 99 5 50
    t 256 224 320 224 0 1 -0.9117717732516294 0.5832571155113225 100
    c 256 224 160 224 0 0.000009999999999999999 0.6832571155113225
    r 256 224 256 128 0 100000
    g 320 240 320 304 0
    v 432 304 432 128 0 0 40 1.5 0 0 0.5
    w 320 240 368 240 0
    w 368 240 368 304 0
    w 368 304 432 304 0
    v 96 224 96 288 0 0 40 0.1 0 0 0.5
    w 96 224 160 224 0
    w 96 288 96 352 0
    w 96 352 368 352 0
    w 368 352 368 304 0
    r 320 208 320 32 0 8
    w 256 128 256 32 0
    w 256 32 320 32 0
    w 320 32 432 32 0
    w 432 32 432 128 0

I am using this in a second stage amplification (for headphones) in a guitar pre amplifier circuit from this website, the circuit of same is as below:
http://www.lbguitar.arkku.net/miniamp/miniamp.html

simulate this circuit

So while this works perfectly for the guitar or audio signal, using headphones, there is only distortion when i connect this to the 1st amplifier circuit drawn before.

The full circuit - Guitar headphone amplifier - looks like this...

LAYOUT....

FULL CIRCUIT SCHEMATIC ....

simulate this circuit

While the 1st circuit works as a guitar amplifier in itself, the full circuit sounds good, with a bit of fuzz and distortion with headphones.

My question is how to remove distortion in the circuit, in which speaker is replaced with an amplifier input terminal.


texts: PCB, Plated hole with annular ring on only one side

texts:
I need my pads for connectors to be plated so that the pins from the connectors can be soldered. But the bottom side cannot have copper pad/annular ring. I have made the pads as shown in the figure below. Bottom pad size is same as the hole size and the hole is Plated.

Is this the proper way? Will there be risk that the holes will be unplated my the manufacturer?


texts:
I am designing an LED backlight driver as a sub-circuit for a DPI interface.  The backlight in question requires 12.8V.  I am trying to use the TPS61161 and have read through all of the documentation quite extensively.  What I don't understand is that the output voltage is "38V Max" and there is no reference to how the output voltage is set.  Vout is used in a few equations but as far as I can tell, not in a way that actually affects the Vout itself.

Am I missing something? Does the chip just sink any excess voltage as long as the load is in range?

https://datasheet.lcsc.com/szlcsc/1811061825_Texas-Instruments-TPS61161DRVR_C324075.pdf

Thanks in advance!

Edit:
This is all the information I have for the LED's:

I have just wired up the following with a variable power supply that I have and got no illumination and a very hot power supply!  I thought this would work to dim the backlight from the pi?


texts: Physical significance of singular matrix in two port network

texts: In class we've been introduced to two port networks, and I was wondering: Is there a physical significance to a singular matrix in a two port network, or is it simply where the mathematical model breaks down?


texts: Questions regarding Gallium Nitride semiconductor devices in Switched Mode Power Supplies

texts:
I have a couple of questions regarding the use of Gallium Nitride MOSFET devices in a DC/DC converter design of mine. My topology is an LCC full bridge converter.

My knowledge is not at expert level so if anything I say is incorrect, please correct me. Typically in these converters, with Silicon devices, the body diode of the device acts as a freewheeling diode to resonant current when the switches are off. However, in Gallium MOSFETs, there is NO body diode.

Furthermore, typically to remove turn-off losses, capacitor/resistor lossy snubbers are connected in parallel to slow down the dv/dt of the switch and to avoid hard-switching at turn-off. However, since Gallium Nitride devices have no reverse recovery current - will the lossy snubbers be needed?

My questions are twofold:

How do Gallium Nitride devices commutate current when they are switched off? Will an external diode need to be included to provide a current path in this situation?
Is there any point using snubber networks across full bridge resonant circuits that include Galium devices if there is no reverse recovery charge? Or are they lossless under switch off anyway? Is there any point soft-switching GaN devices at all?


texts: Not understanding current direction for this specific circuit (very basic question)

texts:
For the following circuit, I am for some reason just having troubles with understanding why the current (circled blue) moves in the up direction across the capacitor.

Or for example, this following circuit why it also moves up across the capacitor.

Why does the current just not flow down?
What causes these capacitors to discharge?

Essentially what causes one capacitor to discharge while the other one charges?

Updated:

What is the case where a capacitor is in series with a capacitor and resistor in parallel, that the top capacitor will always charge, but the bottom capacitor will charge and then discharge back through the resistor:


texts: Convert Iphone 3.5mm pin to standartd Samsung Android 3.5mm pin

texts:
This is a simple question.
I want the new Iphone EarPod to work with Samsung/Nokia phones.
I tried to use the headphone to Samsung phones. Here is the result

Here is the Universal 4-pole Cell Phone headset pinout, the one which Samsung/Nokia make.

Now the question is:

How can I make a converter/adapter for the pin to work well with Iphone EarPad? (I don't want to cut the wire and check which wire works for which function)
Is there a way to make a simple circuit within the connector which makes the impedance match?

I'm really not in the electrical engineering field, so please consider me as an absolute beginner.

I don't care whether the play/pause/vol.up/vol.down functions works or not. I'll consider it as an added advantage if it is possible. :) But I need mic & the speakers to work well.


texts:
Complete newbie here.
I've been trying to reproduce a simple fuzz pedal using breadboard. Here is the scheme:

And here is the current state of my breadboard:

The only sound I hear is white noise like "jack cable sound". What am I doing wrong? I assume I've completely misunderstood some basics, so any tips or guides would be helpful.
And so sorry for the poor question quality.

UPDATE:

Here is the transistors I have at the moment

And also instead of 100k linear potentiometer I've used 10k one. I suppose that's an issue too?


texts:
I plan on running about 15A through a trace on a PCB for about 5 seconds. Does the trace need as large as a trace calculator would say?

In other words for 15A how big of a trace on a 2oz copper board would i need?


texts: I'm working on IR transmitter circuit. But R77 feedback resistor creating confusion about its working. I know it's acting as a current limiter to the LEDs but confused about its role in feedback. Can anyone explain the working of this this circuit?


texts:
I am currently working on a led matrix display project. It is not prebuilt and it will be built it using individual leds. The size is 16x16.

I have been searching about on how to drive the display and I have found out that a popular way is by daisy chaining max7219 chips. But the problem is, that chip is not available here in my area.

I am thinking of using 74595 shift registers instead since they are available here. I'm planning to connect two registers to control the columns and another two to control the rows so that I can show my output through multiplexing.

Is my plan okay? Or are there other chips that are being used to drive matrix displays (I will look at my local shop if those chips are available). Thanks!!


texts: Trying to understand why MOSFET is not switching

texts:
I am experiencing an issue with the N channel MOSFET below:

The MOSFET is not switching at all and I would like to understand why. I have used a similar circuit to control an LED and it always worked fine.

The HEATER_ON signal is either 30V or floating. I am measuring with the scope and I can see 5V at the gate but there is no voltage drop at the load.

What could be the reason? I know I could do this differently but I just would like to understand the reason.


texts: I learned about ECL (Emitter Coupled Logic), but I never found devices or use-cases. Is ECL a historic topic or are there still use-cases?


texts:
I've searched and can't seem to figure out what power cord I need to get for this device. On the back it says:

Power: Input --> 100-240V, 50/60Hz   Output --> 12V-2A 5V-3.5A

Thanks in advance.


texts: Does transformer's flux (due to load) need to obey Faraday's law

texts:
I believe I have a good understanding of a transformer. But I may have a misunderstanding somewhere that is leading to absurd conclusions.
My overall understanding
If we ignore all losses and look at all the flux components in the core of a transformer with rated load, There is a small portion of flux (magnetization flux \$\Phi_{mag}\$) devoted to maintaining both PRI and SEC side coil's voltage. While there is a big clash of Titans between flux generated by the load on SEC (\$\Phi_{SecLoad}\$), and the flux generated by the source (trying to supply the load) on PRI (\$\Phi_{PriSupply}\$).
Further thoughts and feeling ridiculous:

Since \$\Phi_{SecLoad}\$ is only dependent on the load (or more
precisely  \$I_{SecLoad}\$), and it is    being cancelled in the
core all the time. I doesn't contribute to any    meaningful
Faraday's law, or to say: \$N\frac{d\Phi_{SecLoad}}{dt}\$    doesn't
really mean anything, it cannot manifest itself to be some
voltage we can measure or model like \$\Phi_{mag}\$.
if we can discount various losses, \$\Phi_{SecLoad}\$ and
\$\Phi_{PriSupply}\$ can go to infinity!? they will cancel each other
anyways. So loss is the only real world constraint on
\$\Phi_{SecLoad}\$ and \$\Phi_{PriSupply}\$?
The core can never saturate when supplied with rated voltage
(discounting the polarization of the core during startup), again,
because \$\Phi_{SecLoad}\$ and \$\Phi_{PriSupply}\$ cancels each
other.


texts: How to control a motor driver (BTS7960) without PWM

texts:
Using a Raspberry Pi 3B+, I need to control a motor which works in 12V and can draw up to 2A. It doesn't use PWM. It just goes in one direction or the other (reverse/forward) when interchanging the +/-.

Since the Raspberry Pi can't do that alone, I bought an external 12V/10A power supply and a motor controller called BTS7960 (datasheet: here, image below).

What I did:

Connect the external power supply +/- to the numbers 2 and 1 respectively (see the image below for the numbers). It works: I measured the voltage with a voltmeter between 2 and 1, and it shows 12V.
Connect the Raspberry Pi PINs 2 and 6 (i.e. 5V and GND) to the letters B and A respectively (again, see the image below for the letters). It also works: I measure 3.3V between B and A.
Connect the motor +/- to the numbers 3 and 4 respectively.
Connect the Raspberry Pi PINs 36 and 38 (i.e. GPIO 16 and GPIO 20) to the letters E and F respectively. I assumed that setting HIGH these PINs would "enable" the corresponding voltage (+12V/-12V) between numbers 3 and 4 so I can control the motor in both directions. Is this true? Should it work like that?.

However, when I set HIGH one of these PINs (GPIO 16 or GPIO 20), I measure a voltage of +/- 0.01V between numbers 3 and 4 instead of the expected +/- 12V. So it seems to work a little because the voltage switches from positive to negative correctly (and becomes 0V when both GPIO PINs are LOW), but the value is totally wrong (0.01V instead of 12V).

What did I do wrong?


texts: Using Buck Converter as Solar Charge Controller ? (see pic)

texts:
Can I charge Li-Ion safely by connecting PV Panels to a CC CV Buck Converter then through BMS to a 3S3P batteries?
This is basically a plan for a very small solar powered device that takes in solar power (30 Wp), simultaneously charging batteries and powering the device for a few hours during the day (as long as buck's output voltage > battery voltage) and use the battery when the sun is out (battery voltage > buck's output voltage). The device/load (3W) is to be powered continuously.
Please let me know of any of your concerns, especially in regard to hazards and references.
Note:

The CC CV Buck Converter (connects PV to BMS), some tests XL4016, and datasheet XL4016
The CV Buck Converter (connects BMS to Load), some tests XL4015, and datasheet XL4015
The 3S3P BMS
The PV Panels Voltage and Amperage are as measured while connecting them directly to load, not open circuit.

Please let me know if you need more information that hasn't been shown here or of whatever I am doing wrong, thank you


texts:
Those mini tesla coils were always interesting to me, as they can be battery powered while still producing voltages well into the 10kV range, which lights up fluorescent bulbs and destroys electronics. Most of the designs I found were based on the slayer exciter, but this one caught my attention, as it clearly didn't feature all the components normally found in a slayer exciter coil.

Does this circuit work like the slayer exciter and can it be further improved?


texts: Are AA battery and 18650 battery the same?

texts:
I have an Antex SZ004W0 wireless soldering Iron which uses three 1.5V, AA batteries, but I don't know if it supports rechargeable batteries. I know that it supports non-rechargeable battery named "Kodak Max LR6" because I tried.

When I tried to find the best rechargeable AA battery on Amazon or Ebay I got a 18650 battery) which has dimensions: 6.5 x 1.8 cm.

Based on the dimensions being different, I think that AA battery and 18650 battery are not the same.
Which one can I use in my soldering iron?


texts: How should I design a power bus for a wearable project?

texts:
I am thinking about building a(nother) wearable LED jacket project. The basis will be 60 LED/m WS2812B strips, around 2048 pixels, for a peak possible current draw of just under 125A. In reality I would never run full-white patterns, so count on a peak draw of maybe a quarter of this.

That's still a lot of current and I'm trying to think of a good way to distribute it to the ends of the strips. In my experience with other projects, each strip needs to be directly connected to power and the power bus needs to be very low resistance so voltage drop doesn't cause "reddening" of the strips that are connected at the end furthest from the battery.

I'm having difficulty thinking of a design that is a) high current capacity, b) flexible c) "neat" enough that I don't have exposed wires snaking around and d) field-repairable.

Here is a rough schematic so you get an idea of the orientation of the strips (red and black for +ve and -ve, blue is the signal wire which "snakes" up and down the strips):


texts: Short circuit protection for a boost converter

texts:
Is it possible to add short circuit protection to a boost converter?

My initial instinct was no, as the switch does not directly control the input to the inductor and this means the minimum output is Vin or so.

But are there ways to protect such a converter?


texts: How do I redirect timer output for STM32F10x to a given GPIO pin?

texts: I would like to programmatically send a PWM signal to one of the 16 output pins. One way to do this is to trigger an interrupt on timer reload and on an output compare event, and then to update the corresponding GPIO in the ISR, but this looks ugly. Is there a better way to do this?


texts: How does the drain current flow in a MOSFET when the channel is pinched off?

texts:
Here is what I have understood. Please correct me if I'm wrong.

The depth of induced channel depends on the voltage V. Since the voltage across the gate and  the path along the channel decreases from Vgs at the source to drain end to drain end, the channel is not uniform an is tapered. If the applied voltage Vds is increased to some value which causes the voltage between gate and drain end to be lesser than the threshold voltage, the channel is said to be pinched off.

If the channel is pinched off, how does the drain current flow? It's given in the book that the MOSFET enters saturation region and will have a constant value of drain current. But I don't understand how does the current flow when the channel no longer exists at the drain end.


texts: Is there a way to tell if a Li-ion battery has been discharged to deep even after they have been charged again?

texts: I have a Li-ion battery pack (1s3p) and would like to know if it had been discharged too deep in the past. Is there a way to measure this even though the batteries have been charged again?


texts: Inductor calculation for DC to DC converter

texts: How can I calculate the value and characteristics of inductor in a DC to DC converter?


texts:
I am building a PCB with some ICs. To sum up, I have a global 3.6V supply and I need to have an 1.8V reference for some IOs.

I know the right way to do it is to use a voltage translator circuit (generally an IC), but I was wondering why not to do it with two similar resistors ?

Thanks


texts: Best practice for adding Resistor to PLC cabinet

texts:
My Micro-step drive and PLC need a simple resistor network between their i/o ports.The optocouplers in the stepper drive have a max input current of 15mA, while the controller needs to output at least 20mA to give valid signals. The circuit below satisfies these requirements.

simulate this circuit – Schematic created using CircuitLab

What is a good way to mount these resistors in my PLC cabinet?

Are there terminal blocks that accommodate through hole resistors nicely, or would panel/chassis mount resistors be a better solution?

I have looked at some of the terminal blocks out there, but I haven't seen an elegant solution for adding through hole components. I have looked at panel mount resistors as well, but the power ratings are often much greater than I need.


texts: What is the purpose of a second set of 5v and ground wires found on many basic Arduino breadboard projects?

texts:
On this breadboard schematic (and many others) there are two extra wires on the right side of the breadboard. I am assuming they extend the circuit to the top side of the breadboard, but I don't understand why. When I remove the two wires, the "Button" project still seems to work correctly.

(I am completely new to electronics.)


texts: Should I tie my various DC power supply 0 V rails to ground?

texts:
I'm putting together the controls for a CNC router table I'm building. In the enclosure I've got some DIN rail power supplies, contactors, and terminal blocks.

Also in the enclosure is the VFD for the spindle and the computer interface electronics.

The power supplies supply +24 V (computer interface, sensors, and fans) and +75 V (servo power). Should the negative (0 V) rails be tied together and to ground (and the chassis)? I don't mean using the chassis as a conductor, there are return lines for everything. But should they be tied together?

Is there a typical practice for this in industrial control systems? I'm inclined to tie my 0 V rails together (so everyone’s referenced to the same voltage), but not tie that to chassis ground.


texts: How do I adjust the sensitivity of a PIR sensor

texts:
I use a PIR sensor (https://www.sparkfun.com/products/8630) with Arduino to detect people's presence. The sensor detects very well the movements directly in front of it, but it is less sensitive to motions that are more slender or that are further away.

How do I increase the sensitivity of such a sensor?


texts: STM32F4 USART USB communication with PC?

texts:
I am trying to use STM32 provided example of USART called "HyperLink" which basically runs USART1 on ports PA9 and PA10.

The problem is that my computer does not find any new COM ports.

Do I need any additional drivers or anything else?

PS. I am connecting my USB to CN5 and LD7 goes high, indicating that VBUS is present.

EDIT: Code used

  GPIO_InitTypeDef GPIO_InitStructure;
  USART_InitTypeDef USART_InitStructure;

  /* Enable GPIO clock */
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

//  RCC_AHB2PeriphClockCmd(RCC_AHB2Periph_OTG_FS, ENABLE);

  /* Enable UART clock */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

  /* Connect PXx to USARTx_Tx*/
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_USART1);

  /* Connect PXx to USARTx_Rx*/
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_USART1);

  /* Configure USART Tx as alternate function  */
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

  /* Configure USART Rx as alternate function  */
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

  USART_InitStructure.USART_BaudRate = 115200;
  USART_InitStructure.USART_WordLength = USART_WordLength_8b;
  USART_InitStructure.USART_StopBits = USART_StopBits_1;
  USART_InitStructure.USART_Parity = USART_Parity_No;
  USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
  USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;

  /* USART configuration */
  USART_Init(USART1, &USART_InitStructure);

  /* Enable USART */
  USART_Cmd(USART1, ENABLE);


texts:
I have a circuit of two capacitors and three resitors, where two pairs of the components are in parallel combinations:

I'm trying to calculate the total impedance.

Since \$C_1\$ and \$R_1\$ are in parallel and likewise \$C_2\$ and \$R_2\$ i would think the solution would be:

\$Z_E = R_1 + \frac{1}{j\omega C_1} + R_2 + \frac{1}{j\omega C_2} + R_3\$

However my textbook tells me that the answer is what's given on the picture.

Can anyone clarify this for me? Thank you.


texts:
I need a schematic of voltage indicator with two NPN transistors and two Zener diodes. When the input is 9V one led is lighting, the other when the input is 12V.
This is my progress, but I'm not sure if it's gonna work. I don't know to calculate the values of components.


texts: What is the difference between a voltage-level translator and a logic-level translator?

texts:
(This is a follow-up to an earlier question of mine.)

I would like to use the GTL2000 bi-directional translator IC to facilitate level translation between a 3.3V circuit and a 5V circuit (including bi-directional Digital and Analog I/O, SPI, I2C lines, etc.)

Now the datasheet of the GTL2000 convinces me that this is the right IC for the job. However, at certain points, the datasheet describes the GTL2000 as a "low voltage translator" and that it does "voltage level translation".

So before I order the part, I am trying to understand what this means -- What is the difference between a voltage-level translator versus a logic-level translator? Can I use this IC in the application I stated above?


texts:
A transformer blew around my area. For what I can tell the power did not go out in my apartment but the other complex near me, their power went out. Would a transformer blowing near my complex cause damage devices in my apartment? If a transformer blows does it always cut power to whoever is affected, so if my apartment did not lose power would it have not gotten affected by the transformer blowing?

Additionally if my apartment was affected by a blown transformer would it have tripped the circuit breaker?

Thank you for helping me to understand this I am very interested in understanding how this type of event works and had the perfect scenario to help me understand.

Does it make a difference if it is a transformer on a pole or at a station?


texts:
I wonder how a multi-bytes instruction is executed when there is only 16-bit data bus? Assume the instruction is MOV AX,[10H]. The machine code of this instruction is 3 bytes. By combining the CS:IP registers, a 20-bit address is generated and there three bytes (which represents the machine code of that instruction) is accessed.

                 |           |
        CS:IP -> +-----------+
                 |    A0     |
                 +-----------+
                 |    10     |
                 +-----------+
                 |    00     |
                 +-----------+
                 |           |

As you can see, we have to put A01000 on the data bus.


texts: Finding the first pin on a tps61220 smd boost converter?

texts:
I'm trying to find an unambiguous way of finding first pin of the tps61220. This is the chip I've experienced the issue with, but am hoping that the answer could contain an approach applicable for similar ICs.

The IC is a few millimeters in length so I couldn't take a picture of it. Here is a drawing that points all the visible artifacts:

The packaging in the datasheet is presented below:

There is no notion about the vertical line in the datasheet, and just looking at it, it can point to two different orientations for pin 1.

However, it seems that the key on finding the pin one is in the way the IC arrives packed in the reel. The below image shows an opposite reasoning for where pin 1 is as suggested in the comments. The argument with the demo board in HandyHowie answer seems to be the strongest so far.

Questions

Is this a standard thing that the orientation can only be determined by having the reel?
Is don't take the component out of the reel before marking pin one an advice you would give? :)


texts:
I've been tasked with interfacing with the on-board diagnostics of a vehicle.

Some systems use 7V signalling, some use 5V signalling, some signal up to the battery voltage (which can be as high as 28 V on some bigger vehicles). I need some way to handle these high voltage inputs which may exceed my microcontroller's 5V rating. I was thinking of an optoisolated system but communications need to be bidirectional and fast (100kbits second maximum). As it's OBD-II, I'll need two channels; some vehicles use transmit and receive channels, while others use one channel for both transmit and receive. Are there any options for me to consider?


texts: How do we find the Q-factor of a fourth order active-RC filter? The filter in question is not developed by cascading lower order filters.


texts: An oddity I noticed in passing on the Arduino Due schematic, is the Atmel device requires a 4.7 μF capacitor on VDDOUT, but I only see 10 μF capacitors with 100 nF capacitors.  How does this work?


texts:
I found below PCB from a machine. It has a MCU for control all inputs and outputs and MCU inputs and outputs go through HCT374 IC to optocouplers that isolate all inputs and outputs.

What is the application of this D Flip-Flops?