texts:
I'm currently working on a rgb led panel ( 16x32 1/4 scan rate ) ( driving with stm32f0)
But i couldnt really understand what do i need to do to light up a specific led.
When i apply one clock to R1 pin and latch it(suppose whole pannel lights are closed)
red lights are lighting up from right side of as you see below.
What do i need to do to light up only one single led. I read too much i check some arduino code. but totally failed.if i understand working principle then i think rest is easy.
Thank you


texts: how to compensate power drains in dc circuits?

texts:
This has been on my mind for a while. Lets just take any electronics device. Lets say a mobile phone or a laptop. They have fixed voltage and current, but some components needs higher voltage/current or both. At the same time some components drains power (meaning consuming voltage and current), therefore leaving less power for next components. How do they maintain or amplify power for next components to use?

Might be a silly question, but I never got a clear answer to this question. I saw this thing with capacitors and diodes, how they amplify current, but I'm sure that it only works if you have ac power supply.


texts: Switching Voltage Regulator with WiFi Ethernet Controller Bad?

texts:
I a working on a circuit that has components that need 3.3V and 5V. My power input is 12VDC and can not be changed. The 3.3V components use about 510mA of current and the 5V components use about 155mA.  My first attempt at a circuit used two linear voltage regulators in SOT-223 packages. The 5V reg use 12V as it's input voltage and the 3.3V reg used 5V as it's input. Of course the 5V regulator get's extremly hot and then shuts off (luckily it has thermal protection!)

I have read some other posts on this forum about how to dissipate the heat with the PCB traces and also to do it using the case (which is a possibility in my case), however it would be much preferable for this design for the enclosure to not get warm. People using it may complain. So I am considering using a switching-mode voltage regulator like this AD1509. My concern is with the noise. My board has a WiFi module on it and I am wondering if the performance will be affected by the switching noise. The AD1509 switches at 150kHz and I think WiFi is in the 2.5GHz range so I should be okay right?

Also, do you think the switching voltage regulator will also get hot or if I just a big copper pad under it will it be okay?


texts: Why would one still use normal EEPROM instead of flash?

texts:
Is there any reason why people are still using (and implementing in new systems) normal EEPROMs instead of flash memory, nowadays?

From the Flash memory wikipedia:

  Flash memory was developed from EEPROM (electrically erasable programmable read-only memory).

Would there be any disadvantages (power consumption, space, speed, etc.) on using flash instead of normal EEPROM?


texts: I lost a device's power adapter, what should i seek for a new power adapter?

texts:
i bought an expensive desk lamp from the US called Lumiy Lightsblade 1500s, i lost the power adapter, so my questions are as you are electrical engineers:
1) can i use it in israel (The standard voltage is 230 V and the standard frequency is 50 Hz.) ? does it lose its peak because the countries difference?
2) what power adapter should i seek for when buying?


texts: Calculate duty cycle of flyback converter

texts:
MY ATTEMPT
I found a formula for the DC transfer function for the flyback converter:
$$\frac{V_{out}}{V_{in}}=\frac{N_s}{N_p}\cdot \frac{D}{1-D} $$where \$ \frac{N_s}{N_p} \$ must be the ratio between the number of turns of the two coil-inductors, and \$ D\$ is the duty cycle. And since we know \$V_{out}\$ and \$V_{in}\$, we just need to find \$\frac{N_s}{N_p} \$, and then we can solve the equation with respect to \$D\$.
However, I can't seem to find any way to find the \$\frac{N_s}{N_p}\$-ratio, when I only know the inductances of the coils. How can I arrive at the value for \$\frac{N_s}{N_p}\$, so that I can solve the original equation?
I hope someone can help me with this.
Edit 21/02-21
Here I am, one year later going through this problem again, to see if I can solve it. However, even with Andy aka's formula \$\frac{N_s}{N_p}=\sqrt{\frac{L_s}{L_p}} \$ I am unable to solve it.
$$\frac{15 \text{V}}{110\text{V}} = \sqrt{\frac{16.2 \cdot 10^{-6}\text{H}}{1.28 \cdot 10^{-3}\text{H}}} \cdot \frac{D}{1-D} \Rightarrow D=45.20\% $$
But the correct answer is \$D=46.15 \% \$ (according to my instructor). I even tried to take into account any mutual inductance assuming zero flux leakage and 100% magnetic coupling
$$M=\sqrt{L_sL_p}= \sqrt{16.2 \cdot 10^{-6}\text{H} \cdot 1.28 \cdot 10^{-3}\text{H}}=0.144 \text{mH}$$
But that didn't get my anywhere.
Final edit
After approximately one year, I finally solved the problem. Since \$V_{in} \$ is in RMS, you have to multiply with \$\sqrt{2} \$ to get the peak voltage.
$$\frac{15 \text{V}}{110\text{V} \cdot \sqrt{2}} = \sqrt{\frac{16.2 \cdot 10^{-6}\text{H}}{1.28 \cdot 10^{-3}\text{H}}} \cdot \frac{D}{1-D} \Rightarrow D=46.15\% $$


texts:
I have to compute current in the resistors shown in the following diagram

Which I have done using mesh analysis as follows:

However the correct values of currents passing through the resistors are given to be 0.8 , 1.4 , and 2.2 amperes. Where have I done mistake in the whole method?


texts: PIR sensor (with open collector) + Arduino - anomalous results

texts:
I'm attempting to get a PIR sensor working with an Arduino Duemilanove. Nothing fancy yet, just attempting to get accurate high or low values from it first.

The PIR sensor was bought from Cool Components. The alarm pin is an open collector and I am therefore using a pull up resistor (10k). There is a fritzing breadboard diagram below. The wire colours from the PIR are not the same however. Looking down at the circuit side of the PIR sensor with the wires at the bottom they are: red - brown - black (There is a link to an image of it on the Pirate Pad link below). So, here is the first point of confusion:

1) The datasheet for this component (check PiratePad) as supplied on the product page implies that the power should be the black wire and the alarm should be red. I've tried the circuit both ways and am getting anomalous results with both.

The second point of confusion is:

2) ...that depending on which way round I wire the power & alarm I am getting either no changes at all to the values from the alarm pin or seemingly random fluctuations between high and low.

Diagram:

[RM]: As built: Note that connector housing appears to have retention latch slots on opposite side to website photos. If so the as-built diagram is as per mechanical pictures and the opposite of the word instructions.

int pirPin = 2; //digital 2
int ledPin = 13;

void setup(){
 Serial.begin(9600);
 pinMode(pirPin, INPUT);
 pinMode(ledPin, OUTPUT);
}

void loop(){
  int pirVal = digitalRead(pirPin);
  Serial.println(pirVal);
  if(pirVal == LOW){ //was motion detected
    Serial.println("Motion Detected");
    digitalWrite(ledPin, HIGH);
    delay(2000);
  }
  digitalWrite(ledPin, LOW);
}

And this is a few sources of information that I've found and followed to no avail:
http://piratepad.net/sbIgN9KIeB

Any advice would be gratefully received.


texts: How large current is needed to get a voltage change over a capacitor?

texts:
First off, this is question from my homework.

I'm not sure I understand the question, wouldn't the needed current be > 0?


texts: What is the most common practice in performing EMC tests for PCB assemblies that will be sold without a housing? In my case it is an FPGA development board. Is it possible to design excessive switching hardware in a way that it passes CE and FCC testing without a metal housing? Or do you usually define a designated case of application with a housing?


texts: KiCad pin reordering from PCB designer to avoid crossings

texts:
Sometimes pins of a part are equivalent in the sense it does not really matter which is used (typical examples being connectors, terminals, GPIOs.)
Is there a way in KiCad to reorder the pins in the PCB designer PcbNew so that crossings are avoided and feed those changes back to the electrical schematic?


texts: What is the equivalent of a beep on a multimeter without a beeping function?

texts:
I have a multimeter that does not have a beeping fucntion and I need to test for continuity.

Set to 200 Ω, the multimeter shows 1 when the probes aren't touching, and 0.9 when the probes are touching. When I touch the probes to the two things the continuity between which I wish to test, the multimeter gives me numbers in the range of 60-80.

What is the equivalent of a "beep"?

What is the significance of numbers less than 1 or numbers greater than 1?


texts:
I'm looking to replace an ADC chip from an ADS1015 to a MAX11612.  Currently I'm using an Adafruit ADS1015 breakout board, but I need an ADC that is truly bipolar and reads significantly faster (>10kSPS).  I think a MAX11612 will do the trick.  The AIN voltages will be +/- 7.5 volts (between 5 and 10, depending on what works best).  The SDA, SCL, VDD and GND are all connected to a Raspberry Pi and I'm using the Pi's 5V rail as VDD and the Pi's ground as GND.

I'm concerned about the voltage on the SDA and SCL pins going from the ADC to the PI, which needs to be <3.3V.

FB1 are two ferrite beads (810-MMZ2012Y152BTD25).  The circuit is largely inspired from the ADS1015 breakout board.

Here is the link to the MAX11612 datasheet

And here's the MAX11612 pinout

I've come up with the following circuit as a drop-in replacement for the Adafruit breakout board.  Can anyone tell me if this will provide the protection that I need for the SDA and SCL pins and give me the voltage range on AIN0 that I need?  AIN1 will be used as the signal ground reference and AIN0 is the signal input.

EDIT:  Here's the schematic with a proposed level shifter.  Is this the right thing to do?


texts: Is STM32 RTC halted during debug or not?

texts:
I'm working with STM32F411RE but I presume the problem is the same for any STM32F, and possibly others.

I couldn't find in the reference manual whether or not the RTC is halted during a debug session. For any other IPs, including those clocked with different clock sources like the watchdog IP, it's clearly mentioned that debug halting is configurable or at least the behavior is fixed and given.

What about the RTC ?


texts: How can I generate a circuit image from VHDL?

texts:
I've seen this question: How can I generate a schematic block diagram image file from verilog?, but it talks about verilog, not VHDL. Some answers to that question mention paid tools, and I'm looking exclusively for free, non-commercial tools.

I would like the process to be completely automatic and not manual. I would also like the image to consist purely of logic gates. I've tried researching but I couldn't find anything.


texts: What are the constraints when choosing R value for a RC time constant?

texts: I am planning to use a RC circuit to satisfy power up ramp rate requirements. Does the R value depends on system current?


texts: how to switch on a inverter when my fridge thermostat switches on

texts:
Good day,
I have a 220v 65W fridge that i use for camping and a 12v/220v  1000W inverter.
I need a circuit diagram that will switch on my 12v/220v inverter when my 220v fridge thermostat switches on. The same inverter will then power the fridge until the thermostat switches off again.
So when I plug in the fridge to the inverter's 220v output, the thermostat will be on because the fridge it warm but the fridge won't run because the inverter is off. The inverter must then sense that the thermostat is on and then the inverter must switch on as well. The reason i want to do this is because i dont want the inverter running while the fridge is off because the inverter pulls 5.5A from the battery while running with no load and this uses up power from my battery. The fridge itself only draws about 5A from the battery ( apart from the Amp spike when it starts) .I only want the inverter on when the fridge needs it. I would also need a 30seconds delay if possible from when
the inverter switches on till  the fridge gets power if possible- to give the inverter to start up properly .
I am not a elecronics boffen and would like as simple as possible circuit that I can build myself.
Any help would be appreciated.


texts: Start bits in asynchronous serial communications

texts:
I understand synchronous serial communication conceptually but I'm having trouble with how asynchronous works. Specifically in this situation:

Let's say I want to send a byte: 0x03. We have a start and stop bit, which are low and high, respectively. How does the receiving device "know" that I'm sending a start bit followed by 6 0s? How does it know that that isn't just one long start bit?

Followup: what exactly is a UART? I'm asking what the common use is, as I've seen various places refer to it as a standard and others as a piece of hardware.


texts:
I would like to know what does it mean when someone says "that the transconductance of a FET or MOSFET is less compared to that of a bipolar junction transistor (BJT)".

I even heard someone saying that "This particular JFET has lots of transconductance (about 25mS at its Idss of 6-12mA)" What does this mean? And how does he know this? Is it given in the datasheet of every single JFET?
There is something related to transconductance in a datasheet which is the following:

I know that the Idss is the maximum current that a JFET can handle.

I also know that the transconductance of a device is useful to calculate the gain of a device, unless we use emitter degeneration.

For a BJT the transconductance is: \$g_m = \frac{I_c}{V_t}\$ where (\$V_t\$ is thermal voltage)

For a JFET the transconductance is: \$g_m = \frac{I_d}{V_{gs}}\$


texts:
I am using aTI C2000 f28027. I am modelling my program on the examples from controlSUITE. One example that demonstrates ADC (code) connects the ADC internally to an internal temperature sensor. The ADC has 12 bits of resolution. When the program is run and monitored with the debugger values returned by the ADC vary by one count between sampling. Another example that demonstrates the ADC reads values from external pins. When I connect the pins to stable and known voltages (0, 3.3, etc), hte values reurned vary easily by 100 counts (out of 4096) between samples that are displayed by the debugger (I am sure the debugger doesn't display at the same high frequency that the ADC samples).

Is that to be expected with wire connected and unsoldered connections. By default the board uses an internal voltage reference. The temperature sensor code uses a 40 cycle sampling window; I changed the sampling window in the other code but it didn't make a difference. I tested on a voltage from a reliable power supply which was connected to nothing else.

Update:
output


texts: How does adding resistance to a wound rotor induction motor increase torque?

texts:
I read that adding resistance to the rotor circuit causes the induced current in the rotor to be more in phase with the stator current. This produces a very small phase angle difference between the magnetic fields of the rotor and stator.

Is it true?
Why does it reduce a phase angle difference?


texts:
Is there a method in KiCad to quickly map a pin name to a net label?

Example.

On the picture below, I want to name the wires with the pin names, as has already been done with GND. I'm currently doing this manually for each pin and am wondering if there is a smarter way.


texts: A device that wirelessly, securely posts to a server in response to door opening: off the shelf or custom-make?

texts:
I am looking for an off the shelf component for a project I am currently working on. Due to the nature of the project I cannot go into much detail about the project itself, only give a high level overview of the requirements of the desired component. I am not an electronic engineer, I am from the dark side of software engineering, so please forgive me if any of my terminology is wrong, I find myself thrown in at the deep end of this project.

I am looking for a component which can sit on the frame of a door (with part on the door itself (very similar to a burglar alarm sensor in the UK)). When the circuit is broken, the component should be able to perform a HTTP GET/POST to a URL (probably located on the local network - but not necessarily).

To this end, my component requirements are as follows:

Wireless equipped (not to fussy on standards as this point, as long
as major encryption formats are supported).
Ability to GET/POST to a url in event of a break in the circuit.
Low power consumption.
Configurable
Ability to exchange the power source (swap batteries)

The component should provide a SDK (at this point in time, the language used to call the SDK is not important) which can configure the device (for example, setup network configurations, give the device a unique identifier (as multiple could be used on the same network)). I do not know enough about the range of components avaiable which fit my requirements to specify how configuration should take place, but in my head I imagine it being hard-wired to a computer to perform the configuration.

Are there any such components available which would fit my requirements?


texts: Can I use a single SPST switch and transistors to simulate a DPST switch for POS and GND wires to a load?

texts:
I am wanting to create a system that supplies approximately 24V and 1A to a load (essentially a resistor) for up to 1 second. The process will not be repeated for any one load and there would be no continuing current flow after about 1 second. The positive wire will be switched by a momentary SPST switch but I also want to use an arduino output to have the option of solid state control (Arduino) or manual control (SPST switch). I wish to use 16 SPST switches to control 16 separate loads but I will also need to use switched grounds as I want to use an 8-core conductor from the circuits to the loads to control all 16 of them independently (i.e. the loads will be "matrixed").

My question is can I use NPN transistors as in my below diagram to allow switching of the POS and GND to a particular load via the use of a single SPST switch (i.e. mimicking a DPST switch through the use of transistors)?

If so, I will be needing a total of 192 transistors (aiming for 6 "banks" of 16 loads) so which transistor would you guess would be the cheapest and could handle this sort of current for the brief period intended (1 second)? I was thinking TIP120 / TIP 125.

Lastly how would I calculate the correct resistance of the resistor so that only enough current flowed from the SPST switch to the base of the 2nd NPN transistor to activate it while maintaining maximum current to the load.

Thanks for your help Aaron. So you suggest this arrangement?

Redo circuit http://imageshack.com/a/img674/7408/7QRCHi.jpg

So the resistor between the SPST switch / drain of the P-FET to the gate of the load-negative N-FET isn't needed? (as in no current would flow through the gate as it would all go from the drain to source of that N-FET)


texts: Determining battery run time from Ah and MJ?

texts:
I am working on the following question:

Two 100 ohm resisters are in parallel across a battery. The battery can store 240 MJ of energy and is rated 240 Ah. The battery depletes fully after two hours. What is the current flowing through one resistor.

I did 240Ah/2=120A (i.e. battery supplying 120A for two hours). Each resistor gets half this amount, hence the current through each resistor is 60A.

However, the textbook does the following:

P=RI^2
P=100*I^2
(240*10^6J)/2=I^2 A^2 * 100 Ω * 7200 s
(120*10^6 J) / (100 Ω * 7200 s) = I^2 A^2
I = sqrt( 120*10^6 / (720000) J/Ωs) = 12.9 J^0.5/(Ω^0.5 * s^0.5)
I = 12.91A

Could anyone give some insight into what is going on here?


texts: Simple, low power way to buffer a 500mV threshold signal to an open collector output?

texts:
I have a signal that is 0-500mV when low and 600-900mV when high. I'd like to buffer this signal to an open collector output. The output must withstand a maximum of 3.3V be capable of sinking 60uA.

The power for the detection circuit is provided by a (CR2023) battery that ranges form 2V to 3.2V.

The goal is to find a simple, cheap, low power solution. (By low power, I am shooting for on the order of 1's-10's of uA.)

One solution is to use a low power comparitor like the TS881, but this would also require an external voltage reference to compare to, adding complexity, cost, and power usage.

Another solution would be to use a reset voltage detector like the NCP303, but these are expensive and don't seem to come with thresholds lower then 0.9V.

I feel like there should be a way to do this simply with discrete parts. Maybe somehow taking advantage of the pinch voltage threshold on a JFET? Or the bandgap on carefully chosen LED?

Ideas?


texts:
I am designing a power supply cicruit. The circuit will get it power from PoE (preferably) and external adapter (7 - 12V). For the designing I have been researching online to understand PoE splitter design. From my current understanding I have designed a abstract circuit and want to valid my assumption before proceeding further.

Initially, I was planning to have just DC-DC converter and a full-wave rectifier to get the DC out of the PoE but after reading this, I got to know PoE has some signalling mechanisms and I will be needing a controller (or make the controller on my own using a cheap microcontroller) for signalling part of IEEE 802.3af PoE standard.

The abstract design is below:

Question Regarding Rectifier design using Diode.

I have been considering the diode design (after magjack) as given in this answer. I have included design picture given in the answer.

I am considering the Mode A and Mode B only. I have heard about 4 pair mode in which power is applied on Data pair and Spare pair simultaneously. But I think 4-pair mode wouldn't be beneficial with the current diode design as DC+ applied at two pairs (it will reduce the resistance as well) because diode will block one of the pair and allow only DC+ and DC- from single pair to supply the current. Am I correct? How can I solve this issue with little complexity?
I am planning to use schottky diodes to reduce power wastage in the circuit.

Question Regarding ORing power supply from PoE and Adapter.

I am planning to support 7-12V Adapter. I have placed diodes so that single power supply powers my circuit at a single time. To make PoE preferable, the DC-DC converter for PoE outputs 13V and the external adaptor range would be 7-12V. Is my design correct? I have seen this design somewhere and I think it should work. I am not worried about the dropout with the diode but however worried with power dissipation in the diode (and rectifier diodes as well).

For the over-voltage protection, I am planning to use cross-bar or simple 14V zener diode circuit for over-voltage protection.

Question Regarding MAGJACK

I want to use this magjack as I have few samples with me. I am not sure if it work with PoE as nothing has been mentioned in the datasheet. Please help. My doubts are If it can handle that much current (400 mA)?


texts:
I have an electronic device that I have had for a good few years meaning that it's no longer in warranty. Recently it has developed a fault where the device will turn itself off when more power is being used. After looking online, I found that the cause was more likely a failing capicitor.

My question is what exactly do I look at when replacing a capacitor? When looking at the spec sheet of the original capicitor (https://www.maxcap.com.my/ht.html ) there are plenty of options. (The one I need to replace is rated 35V @ 47µF)

Would I be right to assume that I need to try and match it like for like? E.g, same voltage, working temprature, load life, capacitance?

I can't seem to find the original capacitor being sold online on RS Components or Farnell. I'd appreciate any advice on which capacitor(s) I can use to replace it and why (if it's not like for like).


texts: Why can the regenerative brakes of the Oslo Metro only share energy with other trains if they are "nearby"?

texts:
I read on Wikipedia that the Oslo Metro has regenerative braking, but no batteries to store the energy. Therefore, the energy can only be utilized if there is another train "nearby" to utilize the energy.

How far is "nearby"?

Due to the bottleneck of the common tunnel, all lines have 15 minute gaps between departures. That means that there is typically several kilometers between each train, except for on the parts of the network where several lines share the same track (such as the common tunnel and some other stretches.)

Why can the energy not be shared across those several kilometers?
Is the resistance in the wires along the track making it not worth it?
Couldn't the energy be fed back into the grid instead?


texts: Understanding the actual wattage of LED (LM301H)

texts:
LED under consideration is LM301H from samsung:
Product page link - https://www.samsung.com/led/lighting/mid-power-leds/3030-leds/lm301h/
Datasheet link - https://cdn.samsung.com/led/file/resource/2020/03/Data_Sheet_LM301H_CRI80_Rev.5.1.pdf
The product page mentions the wattage as 0.2 W.
However, in the datasheet, max current is mentioned as 200 mA and Vf is around 2.7 V. Product of these values gives 0.54 W. On a side note, there are products available that use this LED and run it at 0.47 W.
What value of wattage should I consider for this LED?


texts: Can i charge 2 li-ion 12v bateries in Series?

texts:
i am making an external batteries arrangement for my laptop. in this i am using two li-ion 12V batteries. now i am facing problem to charge this batteries in series or in parallel?

i have tried to charge my batteries in parallel but after charging every time i need to make my batteries in series for discharging.

so i am thinking to charge my batteries in series and i am not knowing the result to this serial charging.
so my question is 1- what are the pros and cons for serial charging?
2- and if i continue to charge in parallel then pls show me easy way to make batteries in series>?


texts: Can Dual BJT packages be reliably used as Current Mirrors

texts:
Say I need current mirrors, can I just use Dual NPN packages? I know that if multiple BJTs are manufactured in a die, they can pretty much be guaranteed to have the same spread.

Or, should I just stay away from them and just go with those that are labelled as "Current Mirrors".

It's just hard to find the Current Mirror with the right Ft.


texts: How to Check the Validity of Delta-Wye Conversions?

texts: I am solving some basic circuits where I am converting the circuits from delta to wye and wye to delta. Now I want to check the validity of my answers. Any hack for that?


texts: Can I use batteries with a higher-than-recommended current?

texts:
I have a device that says it takes a 23A, 12V battery. I ordered a new battery and was mistakenly sent one with 27A and 12V - same voltage, higher current. Is it safe to use this battery in the device, or will it break things?
Apologies for what must seem like a noob question; I'm not an electronics person. I have found a very similar question but it talks about capacity instead, and I'm not 100% sure whether that changes the answer or not.


texts: Is there a way to detect if there is a Micro USB B cable physically inserted into a micro  USB B receptacle, even if it is just a cable (with nothing attached to it). in android device


texts: DALI : How commissioning process takes place in DALI system -2?

texts:
Broadcast control commands are working properly. But, I am not able to get the response from Dali Driver, for broadcast query or special commands.
And also I am not able to set short address for the driver. Steps followed by me to set the short address: 1. Initialize Command 2. Randomize Command 3. Program Short Address 4. Query Short Address(Not getting any response)
Thanks.
The command  sequence to set a short address when I only have one gear on the bus is:
I sent broadcast with Command 145->>FF91 I got 0xFF.
Then I sent A307(Command257) ->>FF80(Command 128)->>0791(Command 145) but I get no response
I sent FF98 (command 152) get 07
-------------------------------------------------------------------------------------------
Now I can set a short address and turn the lamp on or off when I only have one gear on the bus by follow:
*Set the DTR to the required short address in the special format (shifted left one place, least significant bit set to 1).
*Read the DTR to check that it is correct.
*Send Command 128 Store DTR as Short Address, using broadcast addressing.(But I need to send Command 128 many times,Is this a problem?)
There are some mistakes : Procedure for short addressing when I have two gears on the bus:
I sent FF91 once, got 0xFF once
I sent 0591 once, got 0xFF once   sent 0391 once, got 0xFF once
I sent 0508/0500  once,the lamp on/off.
I sent 0308/0300 once, the other lamp on/off
I sent A500 four times->> sent A700 two times->>sent B5FF ->>sent B3FF ->>sent B1FF ->>sent A900 got no response
And then, I sent 0591 , got 0xFF sent 0391 , got 0xFF
I have sent command 258, but the two gears didn't initialized.
That's Very confusing.


texts: PIC10F200 Breakout Board - Use ICSPDAT and ICSPCLK as GPIOs?

texts:
i am desinging a breakout board for the PIC10F200 at the moment and i am wondering if i am able to use ICSPDAT (GP0), ICSPCLK (GP1) and MCLR (GP3) as GPIOs if i use in-circuit debugging / programming with the PicKit3?
This is how my circuit looks like at the moment:

If i won't be able to use them i am left with only 1 GPIO, which isn't very much, 4 would be much better (or at least 3) :)

Best regards


texts: Response of First order circuit to a pulse input

texts:
Dear All,
Greetings,

I am studying Response of the RC series circuit to a Pulse input.
For calculating voltage across capacitor after pulse input ceases,author considers a time shift.
I am not able to understand what for & why the time shift is considered here
( Highlighted in Red ).


texts:
I am working on an electronics project where I need a two way switch,
that can be controlled using an arduino and can be soldered by hand.
I tried to Google for it, but without luck. Does anyone know of such a component?

EDIT: for clarity: I need to switch between two usb lines coming from a phone. I need also to switch the id line. So usb line from phone -> (usb line 1 OR usb line 2). (USB micro has 5 lines, so I need a five pole, double throw)

Here is a diagram of what I mean:


texts: ΔΣ ADC Programmable Gain Without Amplifier

texts:
There are some ΔΣ ADCs of which one can set an input referred gain. Like if there was a PGA between the input and the ADC, but in fact, there seems to be no PGA between the ADC and the inputs but instead the gain is set inside of the ΔΣ modulator somehow.

For example this one form Analog Devices: https://www.analog.com/media/en/technical-documentation/data-sheets/2480fe.pdf

Am I right, that there is no amplifier between the input and the ADC here and the gain is set somehow in the modulator?
How is that even possible, setting the gain in the ΔΣ modulator.

I am interested in this, because, if I am reading the datasheets correctly, there will be an input current I need to account for even though if I set a gain to the ADC, since there is no amplifier on the input. But, if I am wrong, then the amplifier should provide a high Z input and decreased input current.


texts: Measuring a varying capacitance using the Wien bridge

texts:
I am going to make a capacitive soil moisture sensor. The principal that I'm going to use is the change of capacitance of the soil with moisture. What I'm going to do is make a capacitor that would be buried under the soil, and connect it to an oscillator. Then I'm going to get the output frequency from the oscillator and use it to calibrate and measure the moisture level of soil.

If I am to use a Wien bridge oscillator, will it give me a considerable change in frequency if I replace the one of the capacitors (C1 or C2) with my sensor capacitor? Refer image below.


texts:
The situation is: I have two sources of power. A battery rated for 6v-60v and a USB-C connector able to deliver up to 20v.
What I need: Manage the power so that the battery is the main source and the USB-C is used instead only if the battery was unplugged (battery has precedence over the USB-C).

What the black box should do: It is supposed to realize if the battery is connected. If not, the USB-C should be switched to the battery bus. If the battery is connected, the USB-C disconnects and the system is powered by the battery. Note that it's important that the USB-C has to be connected to the battery bus, as show in the picture, if there's no battery cell plugged in.
What my question is: What topology to use for the black box or, please, give me a suggestion of a schematic to achieve my goal, considering the points I've mentioned before.


texts: Frequency to achieve maximum power transfer in a RLC circuit?

texts:
Consider an RLC cirucit in AC as in figure.

simulate this circuit – Schematic created using CircuitLab

Suppose that I can change only the frequency of voltage. What  frequency will maximize the dissipated power in the resistor?

I'm trying to use Thevenin's Theorem but I do not think that this is the right situation for it, since I'm not changing the resistor but the frequency. How should I approach this situation?


texts: I am designing an information kiosk with touch screen to display information in a museum. I would like to provide it with a proximity sensor so that the dormant screen would come on whenever a visitor is close to the screen. control under windows 7 would be nice so that a software script would run at the same time.. What is the best way to achieve this ?..


texts:
I am using a Step Down Converterto step down 3.3V to 1.8V with a Load current of 500mA.
I have an output inductor of 10uH and 1.2A rated current.

I have designed my converter with the help of this TI Buck converter app note

I am trying to calculate power dissipation of the converter and the junction temperature. Please tell me whether my approach is right.

First I calculate the output power by multiplying the output voltage and RMS inductor current. With this output power and efficiency, I calculate the input power. From the input power and input voltage which is know, I calculate the input current.

And I calculate the MOSFET Conduction loss which is present inside the IC, by (Inductor RMS Current x Inductor RMS Current x Rdson(for High side) x Duty Cycle) + (Inductor RMS Current x Inductor RMS Current x Rdson(for Low side) x (1-Duty Cycle)).
I have not considered the switching loss. If anyone can tell me how to calculate the switching loss, It will help me.

So, Overall, Total Power Dissipation = (Input Power - Output Power) + Mosfet conduction loss. Is my calculation of total power dissipation correct?

And with this total power dissipation, I multiply the thermal resistance of the device and add my ambient temperature to get the maximum IC junction temperature.

Junction temperature = (Total Power dissipation * thermal resistance) + Ambient temperature.

Is my approach for power dissipation calculation and junction temperature calculation correct for the step down converter used?
And for the output ripple voltage, (which will be dependent on the output load voltage tolerance,right?) how will I calculate?
And can someone tell me how to calculate the output capacitor ripple current as well?

Thanks.


texts:
Very basic question here that I thought I knew the answer to until last night, but now I am very confused. I picked up some 12v DC squirrel cage fans for a chassis I am building. Here is the Mouser part.

http://www.mouser.com/ds/2/632/bfb97x94x33mm-519308.pdf

Also here is the supply I am using (RT-125D)

http://www.mouser.com/ds/2/260/RT-125-SPEC-806385.pdf

Here is my question. The 12V rail of that supply is rated to 2A. Those fans are listed as 12v at 1.8A each. I got two of them to run in parallel last night off that supply. That should not have worked right? Those fans would have been drawing too much current from that supply right? I'm just try to understand the limitations of the supply. Maybe that was just a poor choice of supply, but it seems silly to me that the cooling fan in a chassis can suck up 90% of the load a supply is capable of (at least on this one 12v rail). Is this a huge conceptual misunderstanding?

Thanks


texts: Why does my IR receiver spit out random codes when my motor is on?

texts:
I'm learning electronics and trying to understand why my IR receiver spits out random codes when my motor is on.

I have a basic setup with this:

Arduino
Power supply set to 5V
IR sensor receiver module
PN2222A transistor that turns the motor on/off
3-6V motor

When the motor is off, my IR sensor detect all my commands sent with an IR remote and works well. But at the moment I send the command to turn on the motor, the motor turns on and the IR receiver starts to blink and send random codes.

This tells me that, because the motor is draining power, the receiver acts weirdly. In fact, when I connect the motor directly to the tracks of my breadboard, I have the same problem (without transistor and connections in between).

Edit: Schematic added

What is the cause of this behavior? A change in the amperage received by the IR receiver? Is this something else?

Should I add a capacitor (how many farads?) Should I add a resistor (how many ohms?)

Note: I'm actually learning it, so please, don't tell me to go back to school and learn all the laws and formulas, I'm on it. Be constructive and guide me in your responses.


texts: USB Power Only - Detect Device Plugged In

texts:
I have a project that I need to complete for work. We have been working on this project for a while, however I have come to a bit of a road block. I'll first lay out the important points.

We have a Raspberry Pi & a USB Hub with Charge Only cables plugged into it.
We want to be able to turn the power from the USB Hub to the device on/off depending on certain conditions.
The USB Hub, we want to detect if a device (e.g. Smart Phone or Portal Battery Charger) has been plugged into one of the charge cables. We have charge cables currently, they plug and receive charge straight away.
I'm currently using uhubctl to turn on/off ports.
Using Linux, I need to detect a device being plugged in/unplugged

Problem: When I use Data & Charge cables, I fall into 2 issues.

iPhone require their users to "trust" the device first before it will accept charge.
It opens a vulnerability in terms of juice jacking which I'd like to avoid.

Solution: Don't use Data & Charge cables, use charge only. Problem with this approach is I cannot detect a device being plugged in.

With that information, I have hit a bit of a roadblock in terms of available hardware to achieve our goal.

So, my question boils down to this:

Is the approach and I'm taking correct. What I mean is: Using the USB Hub & Charge Only cables.
Is there any available solutions out there in the market that you could suggest I investigate?
Is there another potential approach I have not considered that you could suggest?
I don't need any data, so charge cables are a perfect solution if possible (not mandatory though). But, I need to be able to detect if a device has plugged into the USB Hub (or other device that is capable of doing so).


texts: How to make 3 different voltages in a circuit?

texts:
I have 1 circuit composed from 3 little very simple circuits
I want to power them all from a 5V@1A power source.
All of these 3 circuits must be powered at different voltages.
Their current draw I measured for each of them.

A=4V @10mA, B=3.4V @1.6mA, C= 5V @24mA

What can you suggest?

Thank you.

(I re-edited)


texts: How do I get an Arduino (5 V) and MPR121 (3.3 V) to talk?

texts:
I have the Sparkfun MPR121 I2C Capacitive touch sensor breakout board

I have read that it uses 3.3 V, I know that I can't just connect up the 3.3 V power supply output from the Arduino as the communications lines would require 3.3 V as well. How do I connect up the other lines?

I have found a tutorial at Sparkfun's website. The 3rd diagram using the diode - would that be the best way to interface the sensor to the Arduino?

Any ideas or information would be great, my knowledge is pretty low.


texts: Use relays in series to achieve 10kV voltage withstanding

texts:
I'm finding a relay which can withstand 10kV when the contacts are open. But all I found for now can't achieve this.

I'm considering to use several relays with lower rating in series to achieve this. But I've never used it like this, nor saw others done this.

Would I be exceeding any absolute maximum ratings with relays in series?

Would this be safe?


texts: Understanding power dissipation by LDO regulator as it relates to battery life

texts:
We are looking at using an AP2204K-3.3TRG1 to convert 6V from 4 AA batteries to 3.3V to power a microcontroller.

I found that the efficiency of a linear regulator is (ignoring quiescent current) roughly V(out)/V(in).  If that's the case, it seems like we'll be losing 45% of our power to heating the pass element.

If we have 8,000 mAh of battery capacity, would our regulator effectively reduce the usable capacity to 4,400 mAh?

Would that mean that if we use 3 AA batteries instead and get a 73% efficiency converting 4.5V to 3.3V that we'd still have 4,400 mAh of useful battery life?

That is to say, if I have a 3.3V circuit and I'm using an LDO linear regulator, will I get more or less the same battery life from 3 AA batteries as I do from 4 AA batteries due to efficiency and heat dissipation?


texts: Make linker use bank 0 in relocatable mode

texts:
I'm tryin to build assembly project with MPASM/MPLINK for PIC16F628A. Microchip advice that it's better to stay on bank 0 and switch whenever you want different bank, and then get back to bank 0 (to minimise bank switching). That's why I want to put most GPR file registers in bank 0. Also most used SFR registers are in bank0. However the linker is trying to fit data starting from smallest databank which is GPR in bank 2. There is no way to tell the linker to start filling from bank 0, except make bank 2 protected in linker script. There should be better way...

UPDATE:
For those who didn't understand the question (or didn't want):
"How to reserve memory in bank 0 for PIC16F628A addresses from 0x20 to 0x6F in relocatable code mode in more than one file."

What I tried:

1.

file1.asm

FirstBank   udata_ovr 0x20
register1  res 1
register2  res 1

file2.asm

FirstBank   udata_ovr 0x20
register3  res 1
register4  res 1

Of course that doesn't do it because register1 overlaps with register3. I need register3 to be placed on unused bank.

2.

file1.asm

FirstBank   udata
register1  res 1
register2  res 1

file2.asm

FirstBank   udata
register3  res 1
register4  res 1

This will put all these registers in bank2

3.

file1.asm

FirstBank   udata   0x20
register1  res 1
register2  res 1

file2.asm

FirstBank   udata   0x20
register3  res 1
register4  res 1

results linker error

update 2:
The reason I want to fit my variables in bank0 is because most commonly used SPF registers are in bank 0 and I don't need to switch between banks when I use them (which means less code). And no, I shared memory (70-7F) is not enough to fit all variables I need. It wouldn't be optimal to switch banks when I can fit all variables that I use in 99% of the code in bank 0.

Now it should be clear. If anyone that's discussing my feelings actually wants to help I'll still appreciate it.

P.S. I guess I missed the very important keyword "relocatable mode", so I apologize  about that. But please keep your comments/answer on topic. If something is not clear ask and I'll try to change question to be more clear. Thanks to all that actually want to help.


texts: Battery Power Supply w/parallel Voltage Regulators

texts:
Can this be done?
I need to run a Raspberry Pi off a 12 VDC battery. I have two (2) Voltage Regulators (VR) each regulator uses an AMS1117-5 regulator capable of 5 VDC @ 1 Amp.  The full current draw of the Raspberry Pi (RPi) is 0.65 Amps (650 mA).  I would like to parallel both VR – Both the Input and Output.  I cannot use OR Diodes as the voltage drop across the diode would be too much.  The RPi is very voltage sensitive.  What I hope to gain is a very long battery life for the RPi since the battery is 12 VDC @ 6 AH and a low current draw through each VR.  Note:  The current draw does not have to be balanced since the total current draw is less than the rating of an individual VR.   So  Can it be done?  Safely & somewhat efficiently?   THANK YOU!  Barry


texts: Configure Quartus 2 Simulator to run for longer

texts: My simulation in Quartus 2 finishes at 1uS. How can I get it to go on for longer? This is because my test hasn't finished by this point so I can't tell whether or not my part is successful or not with large numbers.


texts: Momentary Over-Excitation Voltage Circuit

texts:
I want to control an electromagnetic brake (fail-safe brake) used along with servo motor. Microcontroller will control the trigger signal for the electromagnet coil.

Electromagnet Requirements:

Overexcitation voltage - 24V, 1A for 200ms.

After 200ms the voltage step down to 8V with current consumption of 0.3A.
Please refer the waveform images below.

The brake coil cannot sustain high current for long time so we provide momentary high voltage to excite the coil and then reduce the voltage to hold electromagnet to its state.

The solution that popped-up to my mind is to use a Timer circuit which will provide the required 24V for 200ms and then switch to 8V using a relay. But as the trigger signal generated is a continuous signal (not a trigger pulse) so I don't know if this solution will work well for required functionality.
Please suggest any other optimized approach.


texts: Can someone please explain to me how a passive filter could possibly have a negative insertion loss? In the attached picture, this can be seen in the C or D curves where the insertion loss dips below 0 dB. I understand the filter is resonant at this frequency, but I don't understand how resonance could lead to a negative insertion loss on a passive circuit.  This seems to conflict with the fact that passive circuits can't generate power.


texts: How to select power (between USB and battery)?

texts:
I'm hoping to power my device with a 3.7V (2x 18650) rechargeable battery which can be recharged within the device using USB (like in a phone, laptop, etc.). I believe some kind of power selector is needed if the device is to be operational during charging. Is there a module out there that enables this?

Thanks

UPDATE --

Changed question to consider 3.7V (2x 18650).


texts: Latency of reading from a large array of i2c slaves?

texts:
What kind of latency is involved into the polling of a large number of i2c slaves? I have an array of 64 i2c sensors slaves which need to send 2 bytes each to the master as rapidly as possible.

As far as I understand i2c, there is one bit for the start condition, 8 bits for the address and mode, then another bit for acknowledge, then the 16 bits of data, another acknowledge and the stop condition. Totaling at 28 bits per slave for the data and protocol overhead.

So, at 400 kbit, I should be able to hit about 223 reads from the entire array of slaves per second, or about 4.48 msecs for each sweep. Is that correct, or I am missing something?


texts: Can single-sideband (SSB) be used with PSK, QAM or APSK?

texts:
I got this question while considering the Nyquist no-ISI criterion, the consequence of which is that if we send one baseband symbol every T (time) then unless the bandwidth B of the channel is at least 1/2T it is inevitable that there will be inter-symbol interference. That is to say, the highest possible ISI-free symbol-rate in a baseband channel of bandwidth B is 2B.

Then, if we multiply this baseband signal with a carrier frequency f, then the spectrum of the resulting signal is shifted right by f, but since the 'negative frequency' portion of the baseband signal also shifts right, it results in a signal that spans from f-B to f+B, and thus has a bandwidth of 2B. Which seems to indicate that in case of a bandpass channel of bandwidth B the highest possible ISI-free symbol rate is B.

My question is, what compels us to transmit the frequency-shifted version of the negative frequency part? In amplitude modulation we can have SSB (single sideband) transmission, where either the upper or the lower sideband is not transmitted: why isn't this done for digital modulation methods like PSK, QAM or APSK?

If it could be done, the maximum possible symbol rate in a bandpass channel of bandwidth B would have been 2B which is a good thing, so I assume there are sound mathematical reasons as to why suppressing either one of the sidebands would stop us from successfully demodulating the signal. Any pointers as to what they may be?


texts: What exactly is source reflection coefficient and input reflection coefficient?

texts:
I just come across learning Microwave Amplifier. And I encounter two similiar coefficients: source reflection coefficient and input reflection coefficient. Illustration below from Microwave Engineer, Pozar, 4th edition

From what I learn this is how 2 coefficients is definded:

\$\Gamma_{s} =\frac{V_1^+}{V_1^-} \$ and \$\Gamma_{in} =\frac{V_1^-}{V_1^+} \$

This make me feel headache since the way they defined mean I suppose they depend on each other: \$\Gamma_{in} =\frac{1}{\Gamma_{s}} \$ but it is stated that they are calculated independently: \$\Gamma_{in}\$ by \$Z_{in} \$ and \$\Gamma_{s}\$ by \$ Z_{s} \$

So what exactly are these two coefficient, and why they are independent even the definition is kind of similar?


texts: What is the job of the capacitor in a 555 circuit?

texts:
Let's say you've got a standard astable multivibrator (AMV) 555 circuit that includes all the wiring, two resistors (R1, R2) and a capacitor (C1). I wonder what is the purpose of the capacitor and how does it affect the frequency?

For some capacitors the frequency is not "clean" - it fluctuates and for some it's very stable, why is that so?


texts:
>
How can i calculate the absolute uncertainty dt in the following case T=(P/A)^1/4
 if P=(5±0.15) and A=(0.3±0.009)


texts: STM32, Keil and *** error 65: access violation at 0x60000000 : no 'write' permission

texts:
I tried to run LCD software in Keil for STM32, but I got

*** error 65: access violation at 0x60000000 : no 'write' permission

Do you know how to solve that error ?
I saw that I can create a MAP, but it didn't work

MAP  0x00000000, 0x70000000  READ WRITE  // allow R/W access to IO space

(Click for full resolution image)

from this definition :

#define LCD_REG              (*((volatile unsigned short *) 0x60000000)) /* RS = 0 */
#define LCD_RAM              (*((volatile unsigned short *) 0x60020000)) /* RS = 1 */

Thanks for reading

I'm using simulator


texts:
I know it from my professor that for a general transformer like this picture if the core was a solid material its area would too big. Thus the core loss increases. To prevent this we use metal insulated sheets. thus the area become less and hence the core loss decreases.

(source: electrical-engineering-portal.com)
My question is that how does the area decrease? I can't be clear. I can visually see that the area is nearly same in both cases.


texts: How to set the oscilloscope to measure potential between two points that aren't ground?

texts: We have to measure the voltage across a-b in this circuit with an analog oscilloscope, but neither of these points are grounded. How should we put the channels of oscilloscope to perform the measurement?


texts:
I was looking through the following datasheet for a Sumida inductor:

http://products.sumida.com/products/pdf/CDR105,105B.pdf

I am creating a library component for a part in this series and when working on the land pattern I noticed a label titled "sick" in the datasheet, pointing to an area between the two pads:

I have never seen this before. Is it some obscure term to reference a part of a land pattern? Might it be an abbreviation for something? Or perhaps is it just a word used internally at Sumida? I'm suspecting the third option but am very curious to know if anyone has seen this reference before and can help to define it in this context.


texts: Recieving and processsing array of data on STM32

texts: I am trying to use RealTerm to send a .txt file containing a 10X10 array of data to my STM32 NUCLEO board using UART. So far I have been using HAL_UART_Receive_DMA and I have been able to store simple lines of data in a 1-D buffer but I would like to store the data as an array that I can then perform some operations on. Do I need to receive the data as one long buffer and then make an array (if so how) or can I receive an array directly?


texts: I'm doing 2 repairs and currently the pads are missing. I have jumper wire and I try to solder it on with flux but the tinned copper wire doesnt stick too the surface. I've been trying for 4 days mow and cant seem to get it. I'm making sure the tip is clean, I'm tinning it, it seems like it just wont stick. Any tips?


texts: reduce voltage for inverter in solar system

texts:
I have a solar system (solar panel, controller, battery and inverter).
Battery have standby use 13.6-13.8V, cycle use 14.5-15V. I set the charging voltage to 13.8V.
The problem is that inverter to 230 AC is designed to 12V and it disconnect on voltage about 13.4V.
(So it disconnect when solar is connected and charging).
How I should reduce the voltage for the inverter? (and keep it optimal for the battery)


texts: Intel iGPU die area and power consumption

texts:
What is the Intel's iGPU area occupied on the die (or transistor count) and what is the power consumpition of the iGPU alone?
Didnt find any information from Intel, quite odd they dont advertise this information in the spec sheet.


texts:
How can I set/unset hardware breakpoints on my STM32F2 (reference manual here)? A search for breakpoint in the reference manual is less than helpful. This document suggests that my processor might have 6 hardware breakpoints.

What is the procedure for setting and removing hardware breakpoints on an STM32F2?


texts: Difference between low output GPIO and input GPIO

texts:
I have been trying to figure out some details of the GPIO handling. I dont really know anything about electro engineering and am pretty much working with common sense all the time. While researching some GPIO limits I realized that the raspberry pi GPIO generally says that you can sink "16ma in OUT mode" and sink "0.5ma in IN mode". I am having a really hard time wrapping my head around what exactly the difference between configuring an output pin in output mode and setting it to Low is compared to an input PIN in whatever state.
Initially my first thought was that a LOW output pin is the same as an input pin. But the simple fact that all the recommendations say that you cannot sink the same current into an input pin and a low output pin makes me think that my thoughts are wrong.
What exactly is the difference between an input and an output pin (set to LOW) on electronics level (not software).


texts: Capacitive touch sensor grid to the Arduino?

texts:
I am trying to build 8x8 grid that consists of capacitive sensors which we have successfully made by using a high resistors and copper sheets. I used Arduino's library to control it, but my problem is how to control all 64 of them. I have access to almost every kinds of Arduinos in my schools's interaction lab, and since Mega has lots of digital pins that I can use, I have chosen that. However even it has 53 digital pins, and I need to use 10 more pins for other components of my project. I have a multiplexer but sensors I have built and multiplexer do not work together. The problem is, in the library from Arduino, in order to control the capacitive sensor, I need to specify its send and receive pins clearly. If I detach the sensor from on-board pins and attach it to mulplexed pins, it no longer has a PIN number to give to the library. I tried to hack the library, but it was a dead end. Does this means that I cannot use multiplexer and capacitive sensors together, or am I missing something?

Any solution to multiplexing problem or any alternatives that I can use instead of 64 capacitive sensors would be greatly appreciated.

EDIT: I guess I found what I am looking for in Sparkfun Website. According to pin calculations of atmega1280, 2 of these would be sufficient. However I wanna be on the safe side, I will order 3 just in case. I haven't bought and tried it yet, but I believe it can do what I try to do. I'll post results after the shipping.


texts: How can I calculate the worst-case Tj of a MOSFET in discontinuous operation at another Tamb?

texts:
I am faced with the task to calculate the maximum junction temperature of a MOSFET in a half-bridge, having conduction losses, switching losses and diode losses. The real difficulty comes from the discontiuous operation of the device. The device is powered only for a small time (say one minute), before temperatures have stabilized which means that thermal resistances of the whole heat sinking system is more or less irrelevant, it seems to be dominantly the capacitive terms that matter.
Up to now, I solved this on a very simplified approach: maximize the switching loss by increased capacitance and snubbers, operate the device at the maximum load at room temperature, measure peak case temperature and calculate the junction temperature from thermal impedance of the MOSFET and measured losses. In the end, the difference to the maximum ambient temperature is added, and a peak junction temperature concluded.
This however, seems to be wrong for at least two reasons:

The actual MOSFET of my measurement might have a much lower initial \$R_{DS,on}\$ than a worst case component. A tolerance of 20% between typical and max seems not to be unusual.
The initial \$R_{DS,on}\$ is even higher, when a measurement is done at increased ambient temperature. In my MOSFETS's case (NTMFD5C466N) the increase from 25°C to 50°C means another 10% higher resistance.

So if the initial conduction loss could be 30% higher, the contribution of them will be even higher than 30% because the \$R_{DS,on}\$ will also rise quicker. But how much will this be?
I have some ideas to find an answer to this:

Ask the manufacturer for a component that is at the upper tolerance end of \$R_{DS,on}\$ and measure at real worst-case ambient temperature.
Use a MOSFET of the same series with \$R_{DS,on}\$ at least of the maximum of my actual type.
Measure "a lot" of typical systems at the maximum ambient temperature and do a statistics based estimaten of the worst case.
Make a detailed simulation model of the heat sink and try to simulate it (seems to be the most difficult approach).

What do you suggest here?


texts:
I am looking to implement the bq24075-Q1 (datasheet) for a school project. This IC can charge a LiPo while simultaneously proving power to the system. The Absolute Maximum ratings sais that the maximum output current is 5 Amps and the maximum charging current is 1.5 Amps. Would I be correct to assume the following:

1) If my system has no battery connected the bq24075-Q1 can pass through 5 Amps to my system.

2) If a battery is connected and charging at the max rate the bq24075-Q1 can pass through 3.5 Amps to the system while still charging the battery at 1.5 Amps

3) There is no current limit on the "OUT" pin. Imagine if the "IN" current can provide a max of 3 Amps (say that is the limit of the wall-wart) and the battery is fully charged. If the System tries to draw 6 amps what will happen? Will 3 Amps be sourced from the "IN" pin and 3 Amps from the "BAT" pin and the IC will overheat and fail?

Thanks in advance for your help!


texts: How and why is "floating input" a valid state for RF/IR encoder IC's?

texts:
RF/IF encoder/decoder IC's such as this one, will accept the address-pin in one of 3 states:

Floating
High
Low

As per this excellent answer, I believe "Floating" input can assume either High or Low value due to variations in the EM field, if I understood it correctly. If so, then why if floating a valid state ? At the time the IC is reading the value of the pin, how does it determine that the pin is really pulled HIGH or LOW, versus a floating-pin that was inadvertently pulled up/down such as due to ambient EM noise (I'm assuming that such a thing is possible).

Also in line with the question in the context of which the above mentioned answer was given, can someone explain, through non-technical analogy, the difference between weakly pulled up/down versus strongly pulled up/down ?


texts: How can output voltage and current of a DC-DC converter both be higher than input?

texts: I'm working on a TFT LCD Supply and using a step up DC- DC converter from Maxim, the MAX17062. I want to find the input current. The datasheet lists that as 2.5mA. I have a doubt: if the input current is 2.5mA and the input voltage is 5V, how can the output be of higher voltage and higher current? I'd say that that would violate the conservation of energy.


texts: What kind of sensor that can detect prolonged contact?

texts:
i'm currently working on project that needs an implementation of certain touch/force-presence sensor on human body surface. I want to place the sensor on my backpack shoulder straps, so that the electrical system of my smart backpack will know, whether the backpack is currently being worn or not.

I have already tried to use piezo electric sensor, but it seems like it can only detect an impulse signal; output signal HIGH when a force is momentarily detected, then go LOW even if the force is still detected (only detect the 1st contact).

I'm curious, is there any type of sensor that can detect prolonged contact, so that the sensor will always give HIGH signal as long as the force is detected? Thanks!!

Edit: There's also space constraint, so i need the sensor to be as thin and small as possible


texts: Where voltage is lost in an emitter follower?

texts: I'd wanted to know what happens in an NPN emitter follower with \${\delta}V=Vcc-Vee\$. At which junction does voltage drop? May this drop be fatal to a transistor?


texts: Finding the amplitude of a multi-tone signal

texts:
How do you find the amplitude of a signal consisting of multiple sinusoids with different frequencies such as
$$f(t) = A\cos(\omega_1t)+B\sin(\omega_2t)\text?$$

I'm thinking that you take the derivative and set it equal to zero (finding the maximum), but I can't really say why this works. This is for communication systems when finding the amplitude of a message signal.


texts: How to control power to a nichrome wire coil heating element with 12V DC and 5A Max current

texts:
What is the best way to manually control the power to a nichrome wire coil heating element with 12V DC and 5A Max current.
I am looking for a simple and efficient way to control it with a knob for user. Rheostats would be way too inefficient as it will need to dissipate 60W of heat!
Here is the link to the NiChrome coil i'm looking to use:
http://www.omega.com/pptst/NIC60_NIC80.html


texts: How to use a (cheap) BMS for discharge only

texts:
I'm building a small robot (for the context, with a pi zero, a PCA9685 motor controller, 8 small servo motors a regulator and an Ubec) fully powered from a 2S 18650 battery.

I've inserted a (cheap) 2S BMS between the (homemade) battery pack (with a small power switch included, and removable 18650 batteries that I remove to charge from an external charger) and the rest of the electronics. My problem is that unless I put some voltage to BMS output (P+ and P-, which are also used when charging) to "boot it up", the BMS refuses to output anything. Once "booted", I can remove the voltage.

I've seen people talkinging about "reseting" or "activating" BMS by charging it in order to make it output current... However I don't want to include a charging plug in my battery pack since I want them to be removable (as I'm too lazy and don't trust much these BMS for charging, since they don't seem to do balancing)...

So is there a way to workaround this "activation" step so that I can just switch on my battery power button and it works?

For reference I've tried with these 2 BMS but had the same issue:
https://www.aliexpress.com/item/32827942991.html
https://www.nkon.nl/sk/k/2S-BMS-PCB-2MOS-2004-D.pdf

Thanks for your help


texts: MOSFET resistor, difference with no gate or gate at 0V

texts:
While measuring a MOSFET resistivity without a gate voltage I have observed that the resistivity obtained for a gate voltage at 0V is 20 times higher than the resistivity observed when there is no gate at all (with classical 4 probes measurement on a material).
Does someone have an explanation for this phenomena?
Thanks a lot


texts:
There are a number of great tutorials online explaining phase shift keying as a means of digital wireless communication, but none of them seem to cover the topic of multiplexing.  At first glance, it seems that frequency division multiplexing (FDM) would work for PSK, but whenever I flip the phase at the zero crossing, it appears the signal naturally gains high harmonics that interfere with higher bands of the communication medium.  Is there something I'm missing? Is FDM even possible on a PSK signal?

P.S. I am new to Stack Exchange and wireless communication in general, so go easy on me.  I looked for a Stack Exchange directly related to wireless but didn't find it. If it exists, sorry I wasted your time. Just point me in the right direction.


texts: Replacing the gimble in a drone controller

texts: as far as I understand that drone controller for a DJI phantom pro has some sort of gimble the controls the direction of the drone. I'm trying to replace that gimble and control  the drone via a Raspberry Pi and I would like to confirm that the signal that coming out of the gimble is a Digital signal not analog. Is that true? Your help is very much appreciated! Thanks.


texts:
Here, in this question, I am referring to 3 stage Lin topology amplifier (differential stage - voltage amplification stage - output power stage + negative feedback).

I am wondering about portion of negative feedback being fed from the output to T3 via resistor network.

Here, in this case, voltage gain equals Av = Rf1/Rf2 + 1 = 23. So, I am wondering if the difference in amplitudes between two base-to-emitter voltages of TR2 and TR3 is increased if we increase the Rf1? And vice versa if we decrease the resistance of Rf1?


texts: How to properly wind a high frequency / high voltage transformer?

texts:
Please, is there any practical tip / caveat I should be aware, when winding a high-frequency transformer? I'm used to wind 50/60Hz transformers and they do work ok, but now I'm trying to make a high frequency (50kHz) step-up transformer, and I'm facing problems, probably related to losses. My final goal is to get 1500V on the secondary, but I did not get even close to that.

The core I'm using is ferrite, model NEER-28/17/12-2200-IP12R (datasheet: http://www.thornton.com.br/pdf/ner_28_17_12.pdf), and a matching reel (http://www.eletrodex.com.br/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/1/_/1_60.jpg), made of bakelite. I think the reel has a bit thick walls, keeping the windings about 1.5mm distant from the ferrite, I don't know if this is an issue.

The PWM signal I'm using is 50% duty cycle, 50kHz, 0V to 12V, and fed to the transformer using a mosfet. I can see a clean and strong PWM signal on mosfet output, I'm sure it's switching completely on and off.

Here's the circuit I'm using in my tests:

Q2 acts as a level shifter, since the PWM signal comes as 0V - 5V, and the mosfet must oscillate on 0V - 12V. R3 and R4 act as a high impedance voltage divider, (1/100), so I can safely measure higher voltages. My goal is to make the transformer produce 1500V in the secondary.

A test with identical primary and secondary, with 3 turns on each, with AWG 20 wire, works good: if I apply 12V to the primary, I can see the same wave on the secondary. A bit distorted, but I guess it's normal, since I'm using a PWM (it's not a sine wave).

However, when I try a secondary with thinner wire (AWG 38) and a few hundred turns, the wave I see on the secondary is horrible, completely distorted, and resulting RMS voltage is way below what it should be.

So, are there any tips on how to lay the turns? I'm pretty confident this is where the problem lies.

Should I lay them side by side, covering the core lenght, or is it better to stack them up and use a shorter lenght of core?
Should I stack primary and secondary? Or keep them separate, with no overlap?
Does wire thickness have any influence on noise and distortion?
When the winding reaches the core end, should I go back slowly in the opposite direction, doing that as many times as needed, or should I bring the wire perpendicularly to the winding start, and start over where I began, making all layers winded in the same direction?

Any pointers will be greatly appreciated! Thank you all very much.

Eduardo


texts: Inverting a (voltage-) transfer function using opamp

texts:
If we have a circuit that - given some input voltage \$U\$ - produces an output voltage \$f(U)\$ (where \$f\$ is continuous, monotonic descending), we can construct a new circuit that behaves like the (negated) inverse \$f^{-1}\$ of \$f\$ (meaning the function-inverse) as follows:

simulate this circuit – Schematic created using CircuitLab
Now I've tried applying that with a funtion \$f\$ that roughly looks like a \$\arctan\$-function (up to a scaling factor) where \$f\$ is implemented using following circuit. I have tested this circuit and it works fine.

simulate this circuit
To check if that worked I built this on a breadboard with a NE5532 op-amp (with bypass cap with +-12V supply) used a 20Hz saw-wave and hooked up an oscilloscope. It seemed to work fine but the output was quite noisy. This was especially noticeable in the flat part (so I'm not sure if it's actually particularly strong there or it is just particularly noticeable to the flat slope).
Now I was wondering, where does this noise come from, and how can I reduce it?
Below is the circuit I actually used (can be simulated, see "DC Sweep")

simulate this circuit
Here's the simulation output that works as desired:


texts:
The vector numbers in this header do not match the vector numbers in the manual AT90CAN128 doc7679 pdf Section 8.1
They appear to be one position out
Can anyone advise on which is correct?


texts: Analyzing BJT differential pair with feedback

texts:
I have an exam next week, and I need to get a real high mark to pass. Therefore I'm looking for some hard questions to solve, and this is one.

While I don't expect a full solution from you here, some guidance would be nice.

What does “assuming B of the BJTs is very high” mean?
How do we seperate the 1 mA source to the differential pair? Because the solution guide says that it is evenly distributed. How?


texts:
While checking old audio equipment, I stumbled upon the RF5609A filter IC.
The only resources I found about this IC are:

Looks like a 7-poles/6-zeros Elliptic LPF, used before and after AD/DA conversion.

I didn't know those ICs to I'm just trying to understand how they work, specifically how the clock input should to be used.

Pag.2 says that the sampling rate of the IC is 50 times the clock frequency.
Pag.3 says that clock to corner freq.ratio is 100 (I guess because the corner frequency is half the sample rate clock).
Does that mean, for example, that if the AD/DA system is sampling at 100 KHz, you'd need the filter corner frequency at 50 KHz, so the clock input should be 50*100 = 5 Mhz?

Also, what is the order of this filter, given the spec 7-poles/6-zeros?


texts:
I'm trying to make a theoretical automated battery charger using a reactor only with logical gates, and I wanted to use charge cycles between 30 and 80% for efficiency sake. I can output a 0 or a 1 whenever the battery gets either below 30% or above 80%, and I have a simple input that turns the charger on and off.
My idea was to make a switch that turns on when battery goes below 30% (first line inputs a 1) and turns off ONLY when the battery is above 80% (second line now inputs a 1 while the first one stopped doing so a while ago), but the problem is that I don't know how this switch is called and if it can be made with logical gates only.


texts: 12 volt 8000 watt battery discharge protection

texts:
We built a home in a country where electricity is a rare ressource. In order to have energy available all day we bought a bunch of solar panels and several 12 volt batteries. We then used a 8000 watt inverter to power the house.

We are concerned about battery life so we thought about adding an automatic shut off to disconnect the load when the battery discharge to a critical level.

At first we wanted to add a contactor or a relay with a voltage meter to trigger the relay and disconnect the load. The problem is finding a relay that can handle a 8000 watt load on a 12 volt circuit is quite hard.

The other solutions is to use the inverter built in switch to cut off the load. The inverter came with a module that you plug in to remotly power off and power on the inverter. It would be pretty easy to hook it up to a small relay.

I have been looking online for a solution but most module I found only handles a maximum of 100 amp load, since the inverter is capable of 8000 watt I don't think 100 amp would be enough, maybe I'm wrong?

We do not want to spend over 300$ and the module cannot be too heavy since we are limited with transport.

I'm reaching out to the community for a solution.

Edit: I think the safest and easiest solution is to use a volt meter that triggers the inverter low voltage switch, using a relay of some sort, when the batteries voltage is too low.
Since the load exceeds 100 amp the load should not go through the volt meter. Maybe by using a shunt, if necessary.

Does anyone know a module that can do that?


texts: BJT in Active/Linear mode -- How can it still conduct current?

texts:
So I've read quite a few books on how BJT's work and all of them seem to gloss over how a BJT in the linear mode with the base/emitter junction forward biased and the base/collector junction reversed biased is still able to conduct current from emitter to collector.

In this situation, the base/emitter PN junction is biased in such a way that the depletion region is very small or negligible. However, the PN junction of the base/collector region has its depletion region widened by the reverse biasing; which makes you think at first glance that no current should be allowed to conduct.

Here is my take on the device theory of why we still see (large) current from emitter to collector for an NPN BJT in the Active/Linear mode. Please correct me if my theory is wrong or has some misconceptions:

Since the base is very thin in relation to the collector and emitter, and it is lightly doped to a P-type material, there are not many holes available to be recombined with emitter electrons. The emitter on the other hand is a heavily doped N+ material with many,many electrons in the conduction band. When the mass amounts of electrons in the emitter get pushed into the base by the emf of the base/emitter battery, the vast majority of them have no holes to combine with. Now we have a situation where we have a high entropy of electrons in the base which begin to defuse into the base/collector depletion region; effectively doping and shrinking the base/collector depletion region into N-type material. When enough electrons diffuse, the depletion region all but disappears into n-type material, allowing the positively biased n-type collector region to sweep those diffused electrons out of the collector terminal. Since the collector is moderately doped to N-type, the diffused electrons are able to pass right out the positive-polarity collector terminal.

So, am I right about entropy playing a role in this by diffusing the base/collector depletion region with electrons to effectively dope it into n-type material?

Thanks!


texts: Create a CMOS circuit from a logic function F=~A+B

texts:
I tried to draw the a CMOS logic circuit, but I don't know whether is is right or not.

The function is: \$  F = \overline{A} + B  \$

$$ F = \overline{A} + B $$

$$ \overline{F} = \overline{\overline{A} + B} \Rightarrow A \times \overline{B} $$

simulate this circuit – Schematic created using CircuitLab

Link to original paper.


texts: Measuring state of charge of a non rechargeable CR123A lithium battery

texts:
Is there a method (voltage, resistance, other...) of measuring leftover charge in a non rechargeable lithium battery?

Background:

I'm trying to get a general overview of power consumption for few battery powered devices which have been running in different conditions for a few days. The devices have a battery level percentage indicator but I don't know how its implemented and would like to do a side measurement.

There are suggestions to measure the state of charge by checking the voltage level of the battery. The problem there are no characteristics for the low power my device is using (5 miliampSeconds every 5-10 minutes).


texts: Why is my pullup resistor more noise immune than a pull down?

texts:
I have a circuit that appears to have some noise problems related to stepper motors I'm driving. When I changed some switches to use pull up instead of pull down resistors, I get better results. Why?
I'm using a PCF8574 digital IO expander for some limit switches. It has an interrupt pin that goes LOW on any transition from the limit switches. The limit switches are mounted on an aluminum frame with no more than 3' of wire. Several of the limit switches are within 1 inch next to a stepper motor, being driven at no more than 2.2A. Digital inputs are pulled low via 10Kohm, and the limit switches connect digital signals to 3.3V. Logic voltage does not seem to be a problem. The stepper motor and limit switch lines are sometimes ran next to each other (no cable shielding).
When I power my stepper motors, the interrupt pin goes nuts (my uC resets interrupt via a read request). As in, the IO expander detects high->low and/or low->high transitions when none of the limit switches are being pressed.
Limit switch state is correctly transmitted if I'm not powering the motors. Problem is only when motors are on.
Stepper motor drivers have adequate capacitors (470uF), and all digital logic have small caps nearby.
When I change from a pull down to a pull up resistor on the digital inputs, the interrupt does not go crazy.
Why do pullup resistors work better for my limit switches?


texts: difference between analog power and digital power

texts:
Could 3.3v pin of the STM32F4-discovery board be an analog power source? If not could I use a regulator for converting it as an analog power source?

I'm making a camera module using an image sensor. Its datasheet says that you need analog 3.3v, digital 1.8v and digital 1.2v source for power supply. What I wanted to do is to connect this camera module to STM32F4-discovery. Since the boards has 3.3v output pins and GND pins, if I use regulators for converting 3.3v to 1.2v and 3.3v to 1.8v, it seems I can provide 3 different voltages to the sensor.
 However, after searching for a while I realised that analog/digital powers are not same. But I couldn't understand so far exactly what is the difference and whether the 3.3v output pin on the discovery board could be an analog power source.


texts: How to parse this protocol with an arduino?

texts:
I'm analyzing a signal from my building's intercom system to my tenant station. Intercom has two wires, +24V/0.27ma, and ground. Every 10 seconds, the system sends a "heartbeat" signal to the tenant station which looks like this.

Signal goes from 24V (idle) to alternating between ~18V and ~30V. It holds the voltage by segments of 100us, and this looks like some kind of PWM signal, maybe a packet with header + data + checksum?

My questions are:

Is this a common communication protocol? I don't know much about electronics.
How would I go about analyzing this signal, given that it's 10khz and that Arduino analog reads are much slower than that?

My goal would be to process it under this form: LOW for 1 frame, HIGH for 5 frames, etc, then reverse engineer it.


texts:
Currently I am trying to read a byte from my dht11 sensor and write it to virtual terminal, but I couldn't find a simple datasheet for beginners. I found a bit complicated mikroC code and set-up which has pic16f628a and lcd. You can find it here That works, but if I add virtual terminal on it. There is nothing appear on virtual terminal even if I add required mikroC codes on it.
While my second try, I replace my microcontroller with pic16f877a, I can see this text on virtual terminal "No response from sensor" which is the error message of my mikroC code.

Here is some info about dht11;
DHT11 uses a simplified single-bus communication. Single bus that only one data line, the system of data exchange, control by a single bus to complete. It sends 40 bit Data format:
The 8bit humidity integer data + 8bit the Humidity decimal data +8 bit temperature integer data + 8bit fractional temperature data +8 bit parity bit.
You can also find datasheet from: here


texts: Microcontroller is being restarted on function return

texts:
I have 8051 MCU and I use keil to program it with C. But in some functions when the function ends and it gets to the return line the MCU is restated. For example a piece of my code is

 while(!ctsWentHigh)
    {
        radio_comm_PollCTS();
    }

while returning  radio_comm_PollCTS()  the MCU is restarted. If I change the code to

 while(!ctsWentHigh)
    {
        cstvals = radio_comm_PollCTS();
    }

it works and the MCU is not restarted. But this solution does not work in all cases and some other functions return and reset the MCU. (not all of them)

I have a doubt that the problem might be for the tool chain integration

Linker settings

CODE REMOVEUNUSED CLASSES(BIT(0x20.0-0x2F.7), DATA(D:0-D:0x7F), IDATA(I:0-I:0xFF), XDATA(X:0-X:0xFFF), CODE(C:0-C:0xFBFF), CONST(C:0-C:0xFBFF))

compiler settings

DB OE BR Small OPTIMIZE(11, SIZE) DEFINE(SILABS_PLATFORM_WMB912) DEFINE(SILABS_WMCU_SI106x)

Assembler settings

XR GEN DB EP NOMOD51

Kindly help if you know the answer I am in urgent situation.

Thanks


texts: Sensor to focus a robot on a welding line. (PLC robotics)

texts:
I'm searching for a way to recognize a welding line in an area. When the line is recognized, a small robot needs to follow the line.

I searched the web already and spoke with some sensor suppliers. Until now nobody could give me a proper solution for this.

My first tough was to go with a vision camera to see if there is enough color difference between the weld and the surounding area. (I don't have experience with those vision camera/ sensors) Is this possible? Is there a better/easier/cheaper way to do this?

Thanks in advance.

Edit 1.
First of all thanks for responding.

The weld locates it self in a large area (square of 40x40 meters.) The weld connects two sheets of steel which form the area. The area it self is quite dark as it is inside without a lot of illumination.

The sensor can be place from a few millimeters upto 200 millitmeters from the weld.  The weld is 20 millimeters wide.

The weld line is not raised as two sheets lay on top of eachother and welded on the side.

The machine should remove the weld. So temperature can't be used to track it.


texts:
I'm learning about grounding and I'm having trouble grasping the theory behind a grounded phase conductor, for example a corner grounded delta system has a grounded phase. My mind is saying
 "no the phase can't be grounded"
wouldn't that create a ground fault? I think this concept might break free some older stuck ideas about what grounding is. Thanks in advance.


texts: Can FPGA be damaged when driving opposite signals?

texts:
Quoting answer from thread "Using signal in different modules vhdl":

  if one drives '1' and the other '0' at the same time, you have created a short circuit across the power supply, and you can potentially damage the device.

Is the damage really possible? I'd think there would exist some sort of protections inside the chip.


texts: Roland MicroCube GX MOD: bluetooth aux in

texts:
I own a Roland MicroCube GX guitar amplifier (see https://www.roland.com/global/products/micro_cube_gx/); I'm pretty pleased with it.
This particular model has, in addition to the guitar input jack, an extra 3.5mm input jack (labeled AUX IN) that allows the user to connect an external input source so that you can hear both your guitar and, for instance, a backing track. This is particularly useful for studying and practicing parts.
Now I would like to be able to send this external signal via bluetooth. I've been looking around and found that the XY-BT-Mini (https://www.amazon.com/Bluetooth-Lossless-Decoder-Amplifier-XY-BT-Mini/dp/B07P2WJSYY) might be a good option, but I have two questions regarding the best way to connect the module so that it is installed inside the amplifier with minor modifications to it.

Connecting the signal itself: Can I connect the output of the module (i.e., the R-G-L pins) to the corresponding pins on the built-in 3.5mm input jack? I guess this means that both inputs (the jack and the input from the bluetooth module) will be connected in parallel; is that ok or even safe?

Powering the module: the amp itself is powered via a AC/DC transformer that delivers 5.7V/2A (so it says on the label). How would you go about taking just 5V from that? (as the module works between 3.5V and 5V)

Thanks in advance for all your help. And please, if you come up with a different way to achieve this, let me know!


texts:
I am working on the design and prototyping of a boost conductor. With that task in hand I have to design a DC inductor for a boost converter. I am using the material EPCOS N27 since its the only one available to me. My RMS current  through the inductor 8.9S and I am using a switching frequency is 150kHz. My question is what is a good selection of flux density and specific power density for this design using the N27 and how does one generally go about selecting these variables.
N27 datasheet


texts: How to draw a PCB in Altium without schematic?

texts:
I'd like to make a PCB but I don't really need a schematic for it (it is just a prototyping board).

I can add components, pads - but I can't add traces (I can start the trace but I can not go to another pad - which is reasonable as there is no net created in schematic).

The second problem is that I can not multiply pads and components: Ctrl-C -> Ctrl-V is not working.

How can I do those things?

UPDATE

I find the way PCB editor doing the Copy-Paste:

I pick the component with the mouse
Press Ctrl-C (I can use context menu as well)
Then I need to pick a reference
After that I can press Ctrl-C and add the component easy

Actually this was described in the gray box in the upper left corner of the screen.

UPDATE 2

I tried different setting and I found that if I press TAB during manual routing I can choose "Ignore obstacles" mode which made me possible to connect the pins (I will just ignore the errors I will definitely get during DRC):

So I'd say that this is not the cleanest way to make the PCBs in general, but it looks OK for my project (a prototyping board).


texts: Is there a 12V stable output regulator for liion?

texts: I need 12V for my system and I want to use 18650 cell. Problem is, that everywhere I looked, only boost converters are sold, which only multiply input voltage.


texts:
Please advice how to design one transformer using full-wave bridge rectifier to control separately for 3 loads. This design is Live only circuit,no ground and neutral.
Do i need more of bridge rectifier? how the connection?
Input AC 240V 50Hz


texts:
I am now learning about voltage dividers and bleeder current.I read article on this website http://www.tpub.com/neets/book1/chapter3/1-35.htm

there is example of voltage divider,it goes like this
"Figure 3-64 is used to illustrate the development of a simple voltage divider. The requirement for this voltage divider is to provide a voltage of 25 volts and a current of 910 milliamps to the load from a source voltage of 100 volts"

Its simple two resistor voltage divider with single load,it says 910 miliAmps and 25 volts so I calculate it needs 82 ohm + 28 ohm resistor for total resistance of 110 ohms and voltage between resistors of 25 volt like the requirment needs.

Then I look at the curcuit on that website and there is 75 ohm and 25 ohm resistor,so that is 1 amp and not 910 miliAmp but then I remember it said something about bleeder current and that I should give the circuit more current than it needs,about 10% of the load rule of thumb.

Ok,that make sense,but then the website says that actualy since the resistance of load creates parallel resistance with that bottom 25 ohm resistor,we need to increase it to 275 ohm from 25.

Now the fact that load creates parallel circuit with the second resistor so the second resistor value should be such value that when connected to the load it will create total resistance of 25 ohm is simple,but here is something I dont understand,where did he come up with 275 ohms?!

Not a single time did he mention what resistance the load is! I read that load resistance is usualy in the mega-ohm range.When I calculated total resistance of 25ohm resistor in parallel with 10 mega ohm resistor I got 24.9999! That is so close that it makes the parallel effect almost non existant,doing what he says is correct way to do it would give the load 78 volt instead of 25,and the current to load will be 285 miliAmp instead of 910 required by the load!

Again I want to stress and remind you that at no point in the article does it mention resistance of load,it would only be correct if the load was 28 ohm,since 28 ohm in parallel with 275 ohm is 25 ohm.I ask,is the knowledge that load is 28 ohm somehow so common,that it isnt even worth mentioning when writing articles for absolute beginers? I dont know what to think about it,do I not understand something properly,or does the author of that article truly think that potential reader would automaticly know that the load is 28 ohm so he thought that it doesnt even need to be mentioned?


texts:
I'm very confused on the idea of pulling resistors. I get that they set the default voltage to a value so that you don't get a floating high or low value, but I don't get the application in TTL.

So if we have 2 chips, Master and Slave (M and S for short). M & S communicate via TX and RX lines. M's TX like has a pull up, while the RX has a pull down respectivly. Assume Slave is reading TX and Master is reading RX. How does the flow of electrons change when RX and TX are switched on and off. assuming that this is a normal universe and electrons flow from ground to supply.


texts: How could I proceed with this circuit to determine the Thevenin Equivalent? I have the values of \$R_1, R_2, R_3, I_2\$ and the time value for g. I first tried to figure out the total voltage for the equivalent by ignoring \$R_2\$ and \$R_3\$, but that did not seem reasonable to me in the end. I tried to solve other examples of (somewhat) similar circuits, which had multiple resistors in series and/or parallel, but I'm still not sure how the ones in this one should be viewed. Perhaps \$R_3\$ and \$R_2\$ should be added as parallel, and then added parallel to \$R_1\$? What comes to the total voltage, the time value throws me off since I do not have much clue on what to do with it, so I thought I could just figure it out via total resistance.


texts:
MY goal is  to design a regulator which could receive (12 V to 60 volts DC as an input) and 5 volt with 60 to 70 mA current as an output. The reason I used three BJT's NPN (Q1, Q2, Q3), so I thought I could get decrease the heat dissipation by dividing the current through 3 different BJTs (60 mA/3)= 20 mA. Power dissipation= (Vin At the collector -Emitter)*current= (50.30_5.33)*20/1000= 0.9 W and I test them on bread board and it gets very hot, and it makes sense because 1 watts will almost = to 50 degree Celcius, plus the ambient temperature which makes it 75 degree Celsius.

Any expert there in designing voltage regulator, with a smart solution, or what would you recommend? If I Increase the RX value to 800 ohm, the collector voltage will decrease from 50.5 to 5.33 volts and that is perfect, but the problem is when I change the voltage back to 12 volt, then I won't get 5 volt as an output. If I miss any information to add please let me know, and I will get back to you as soon as possible.

[
       --- Operating Point ---

V(n004):     11.0833     voltage
V(a):            6.19012     voltage
V(n002):     50.4175     voltage
V(n003):     6.18692     voltage
V(ve):           05.3231     voltage
V(n005):     5.16179     voltage
V(n001):     60  voltage
V(n006):     5.3231  voltage
Ic(Q2):  0.0319418   device_current
Ib(Q2):  0.000319418     device_current
Ie(Q2):  -0.0322612  device_current
Ic(Q1):  0.0319418   device_current
Ib(Q1):  0.000319418     device_current
Ie(Q1):  -0.0322612  device_current
I(C1):   6.19012e-018    device_current
I(D2):   -0.242137   device_current
I(D1):   -0.00180777     device_current
I(R6):   -0.000638836    device_current
I(R5):   -0.0645224  device_current
I(R3):   -0.0322612  device_current
I(Rx):   -0.0638836  device_current
I(R1):   -0.244583   device_current
I(R4):   -0.0322612  device_current
I(R2):   0.0024466   device_current
I(V2):   -0.308467   device_current
]


texts: Identifying mystery electrical connector

texts:
I've recently acquired a Japanese JRC NSC-16 Marine Reserve Transmitter at the rear of which is a connector that I'm not familiar with.  This connects the 24 volts supply to the unit, a number of pins being connected in parallel.  It will also carry the keying line.

I've tried to take pictures of the connector but they are pretty poor quality...

The connector has two rows of 6 pins, these are staggered between pin 2 and pin 3, and pin 8 and pin 9 so the mating plug can only be inserted one way.  There are two 'lugs' on the socket, presumably to secure the matching plug though these appear slightly bent...

I'd be grateful if anyone could identify this for me.

My apologies but being a newbie I can only post two images - and the ones I have posted are not very good...I'll see if I can post others later.

The connector carries the markings HRS followed by some other indistinguishable letters - they may be tot (in lower case) = HRStot?
The connector external measurements are ~390 x 140 mm

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texts: PIR sensor 3.3V output driving a mosfet loaded with 24V power LED

texts:
I'm trying to build a cheap motion activated LED light system.

Circuit is:
24V power --> LED --> LED --> resistor --> (drain) mosfet (source) --> GND

LED are 10V 10W on aluminium heat sink, resistor is 7.5ohm 5W

Flowing current is about 0.55A. I choosed to drive the LED at half its nominal current because I noticed that the light level does not increase proportionally to the current. Two LEDs at 0.5A emitt far more light than one LED at 1A, and heat less.

Due to the 3.3V output level of the PIR I choosed a FQP30N06L mosfet which should have a 2.5V max gate threshold voltage.

PIR sensor is powered with 5V, the GNDs of the 5V and 24V power suppliers are connected togheter.
Mosfet gate is connected to the output of the PIR sensor which can be 0V or 3.3V.
The system is working but the mosfet seems not to be fully on, the LED seems to be at 10%.
When manually activated, switching mosfet gate to GND or +5V, the circuits works great, LED is fully ON or OFF, so I think the problem is related to the 3.3V output level of the sensor.
I guess when powering with 24V, max gate threshold is not 2.5V anymore but raises, so 5V will work but 3.3V is not enough.

Whay would you do?
Should I search for another mosfet which will work in this conditions, or I've better build or buy a gate driver circuit?
TIA


texts: What are all the wire shields grounded to on a system that has no contact with earth, like an airplane? I found this document that says all shields and chassis and other grounds should be connected at a single point next to the main power source ground. What if the power source is a battery and the lightning strikes with a lot of voltage and current, won't that blow up the battery? My guess there should be some big resistor or something that will quickly and orderly convert all that electricity into heat, but that is just my guess. Surely I can't just connect it to the negative on the battery, or can I?


texts: DALI Lighting (IEC62386-209) and Command-In-Between

texts:
Good Afternoon,

I'm having some trouble understanding IEC62386-209 section 12.7.3, which involves sending an "ENABLE DEVICE TYPE 8" command to DALI Control Gear prior to sending an extended (DT8) command.

The paragraph in question for the associated test sequence:

  12.7.3.1 Test sequence 'ENABLE DEVICE TYPE: Application extended commands' An application extended command shall be executed only if
  preceded by command 272 'ENABLE DEVICE TYPE 8'. If there is a command
  in-between command 272 and the application extended command the
  application extended command has to be ignored unless the command
  in-between is addressed to another control gear. The test sequence is
  shown in Figure 85.

My issue is in understanding what happens when an in-between command is sent on the bus, directly after ENABLE DEVICE TYPE 8 (such that it's essentially interrupted)

From what I gather, and according to the paragraph above, the extended command has to be ignored, unless the in-between command is addressed to a different device.

In that case, what happens if the in-between command is not sent to another device, but a device group which the device is or isn't part of?


texts: Is this sequential function chart correct?

texts:
I have to draw the sequential function chart of a robotic arm  which in the beginning of a process is in the position A. If it gets an impulse from the sensor S1 it moves to the left and for  5 seconds reaches the B position,stays for 5 seconds in this position and then gets back to the initial position. If it gets an impulse from the sensor S2, it  moves to the right and for five seconds reaches the position C. It stays for five seconds in this position and then moves back to the initial position.

Is my SFC correct?