texts:
I'm an electronic enthusiast, and very interested in doing experiments and working with whatever I learn in the book.

Recently, I was making a full wave rectifier circuit. In order to find a Zener diode for this purpose, I searched through the net, and it was a utter chaos that I found myself in with the different types of numbering of the diodes and capacitors. My book mentioned that Zeners are numbered usually as 1N.... , that is, Zeners have the prefix 1N. I had to look up the data sheet of each zener available to see which met my needs.

There are similar types of numbering for transistors, ICs and all other electronic components. My question is that, is it possible to identify the characteristics of a particular component by looking at its numbering and not the data sheet? For example, if I say a Zener is 1N5408, as a beginner, I understand nothing but that it is a Zener diode, and then I've to look at the data sheet for other characteristics. Is that the case with everyone? What do you do when you want a particular component with some specifications in particular? Do you just Google it up, or is their some systematic approach to this?

Moreover, can anyone provide me a table by which I shall be able to understand which serial number of components refers to what? For example, BAV99 is a dual diode, whereas BT146 is a triac. How can I understand at the first sight that the given serial number refers to a diode, transistor or such other components? What is their systematic numbering process, if any?


texts: What are the effects of additional layers in Power MOSFET in terms of internal resistance and its trigger voltage?

texts: As you can see in the attached image, due to the additional doping layers between the source and drain the MOSFET achieves a higher control of voltages and therefore can be used in power applications. Unfortunately, one of the counter effects is that each of these layers has a resistance and when all of them are added they increased the internal resistance value. Then comes my question about. If I have a Power MOSFET that has a higher value of internal resistance compared to a common one, does the power device has a higher trigger voltage or the output current might be lower than the input?


texts: What would be the purpose of using a colour code for resistors instead of just printing their values?


texts: USB Qualcomm Quick Charge 3.0 on PC (Linux Ubuntu)

texts:
As nowadays PC motherboards supports USB voltage manipulation I will ask on given example hardware/software.
I am using Ubuntu 20.04 installed on machine with Motherboard Gigabyte AORUS Z390 Master. Gigabyte provides a tool for Windows only called USB TurboCharger in section Utility. This tool allows to switch to Quick Charge 3.0 mode when Android device connected. I would like to use this feature on Ubuntu but I cannot find any information about the technical specification either on Gigabyte nor Qualcomm websites. From the first phase of investigation I know that the device is using one of USB Root Hub (USB 3.0) ports in Standard mode. Now while switch to Quick Charge the device is removing from USB devices and some part of this software takes control on the connection. USB Turbo Charger Details are on page 120 in manual. As there are general information my two questions are:

Is this communication done on Generic USB driver level or the QC protocol requres any specific driver?
Is there any library or application on Linux that can handle it?

Additional Question
If I would need to implement it by my self is there any tutorial to getting started with programming USB Driver it in CPP or Java for Linux?
The option which is comming to my mind would be to install it by wine but I'd rather like to avoid it.

 As I am preety new in asking questions here, thus if someone or something wants to close my question please provide a path where I can ask exactly this question to get some help.


texts: 5v Electret microphone to PC mute switch pop help

texts:
I've got a PC microphone that fires off a loud pop when muted. Upon taking it apart it appears that its mute circuit is really simple and therein may lie the issue.
I've combed this board for fixes and and can't find one. There is this page on the web. The fix seems intuitive but it involves the internal circuit, which is beyond the scope of the mute button; it's inside my sound card and I'll be damned if I have to get in there to fix this. Furthermore, that fix involves a 3 lead mic, where mine is 2. I figure there's clean way to kill this pop without changing (much) the impedance or voltage going to the electret mic.

Please see exhibit A:

This seems to be all the involved circuitry of the microphone (Style #1 is its original form).

I figured I could try bridging the ground to the signal upon muting, so I shorted the 2 points in Style #2. This only increased the pop seen on the audio end of the business
(audio is mic signal. Mic is open and working then at red line is turned off).

Any suggestions as to how to quell this pop? Many thanks in advance for your time and consideration.

P.s. Ideally, I would like to add a band pass filter for 60hz hum and high-end static. If I'm going to be wiring up more resistors and capacitors for the filter, couldn't 2 birds be killed with one stone?


texts: What are carry-lookahead adders and ripple-carry adders?

texts:
I see carry-lookahead adders and ripple-carry adders terms being used often. I have no idea what either means (nor the type of architecture they describe).

Can someone please explain what each one is, why one may be faster than the other, and what each is used for?

Also, are there any external sources that may help with the matter?


texts:
I am trying to use some components from arduino schematics in my design.
Specifically
CAY16-102J4LF (res array 1206 4 res 1k ohm)
1571636-3 (pusbutton smd 6x5 5 pins)
CSTCE16M0V53-R0 (cer res 16.0Mhz 15pf smd)

The schematic capture is ok, but when rendering 3d view the components are rendered like

I have missed something ? Or the troubles come from symbols ( downloaded from samacsys )
Thanks.


texts:
As DC motors generate more back EMF, the current that the motor receives drop lower and lower.

Now if there were a way to extract the back EMF of that motor out of the circuit (I don't know if that's practically possible or not) the current will keep at its maximum and we would get the maximum torque according to:

T= Z.phi.I/6.28

Is this true? If it is so, is there anyway this could be done?


texts: SiPM soldering with T962a oven not working (Pictures attached!)

texts:
For my new project, I was introduced to relatively new topic for me, Luminosity measurement with SiPM.

To do so, I am trying to make a SiPM PCB with SiPM soldered on it, which will be attached to measurement device.

In order to solder SiPM onto SiPM PCB (both pictures below), I was planning to use T962a reflow oven.

In the past, I have successfully soldered LEDs on LED Boards using the reflow oven of T962a.

In addition, the manufacturer of SiPM also recommends standard reflow solder process (Link on Page 5: http://sensl.com/downloads/ds/TN-Handling%20and%20Soldering%20Guideline%20for%20%20SMT%20Devices.pdf)

So, I let the SiPM to be positioned on the PCB as in the picture and tried to solder in the T962a.

However, there was no soldering. It just came out as it was before soldering.

Could somebody teach me what is going on and instructions?

Thank you so much.


texts: What is this electrical symbol? T with overbar in down-pointing triangle

texts:
I'd like to use an old laptop AC adapter in conjunction with an adjustable buck module as a project power supply.
It works, but I'm ignorant of some safety details; for example I'm uncertain whether my adapter, which uses a non-earthed input, is "isolated from the mains".
I've tried researching the symbols on the label, but one symbol which feels relevant I cannot identify:

What is that letter T in a triangle?
Does it mean "safe"?
Or "death"...?


texts:
What can I do to eliminate the output voltage when there is no load on my circuit, even if there is any level on V2?
I have do develop a current source that doesn't provide output when no load. Thanks


texts:
I'm trying to learn a bit more about forward voltage and OHM's Law but I'm not sure how to wire this circuit.

I have:
1 x 4.5 DC motor (Operating Volts: 1.5- 4.5V, Nominal Volts: 4.5V, Current (no load): 0.25A)
- http://www.jaycar.com.au/Electromechanical-Components/Mechatronics/Motors-%26-Gearboxes/Hobby-Motor---Medium-Torque/p/YM2707

3 x 5mm LED (IF Typical (mA)20, IF Max Continuous (mA)50, VF Typical (V)2.1) - http://www.jaycar.com.au/Active-Components/Optoelectronics/Standard-LEDs/LED-5mm-Red-Waterclear-10000mcd/p/ZD0156

1 x 3 - 12VDC Switchmode Plugpack (Output voltage: 3, 4.5, 5, 6, 7.5, 9, Output current: 1000mA (max))

Do I use the power at 4.5V and run the motor and the LEDs in parallel?

Do I need resistors on the LEDs?

Any help will be greatly appreciated!


texts: Using a type K thermocouple ADC to measure a type E probe

texts:
I'm currently trying to measure the temperature of an off-the-shelf soldering iron.
After realizing that the temperature-sensor in the soldering iron is a thermocouple, i ordered a type-K thermocouple ADC board, more specifically a MAX6675-based breakout board.
While I am able to get temperature readings out of the chip, they are way to high in comparison to the real temperature.
For example: I'm getting a reading of about 550°C, when in reality the iron has a temperature of slightly under 300°C.

Looking at this chart in the Wikipedia I think that my iron might be a type E thermocouple.
https://de.wikipedia.org/wiki/Thermoelement#/media/File:Thermocouple_voltages.PNG

Now for the final question:
Is it possible/feasible to convert/calculate the correct temperature (of a type E probe) from the type-K-thermocouple ADC reading?
Has anyone done this in the past?
I don't really need high absolute accuracy, +-10°C will be present due to the PID regulation anyway.

My last solution would be to order/sample a MAX31855E-chip from maxim and then swap the chip out on the board. I don't really want to do that, because the MAX31855E isn't that easy/cheap to source.

Additional information: I'm using an ATmega328 microcontroller, firmware is written in C, so any example code would be highly appreciated as well.


texts: can not get required gain with gilbert cell on ltspice

texts: I designed a very basic Gilbert cell using BJT's. The function is a DSB modulator where one input is a 2.5mvpp sine wave, and the other a 5vpp square wave. The current at the bottom is a simple current source with a biasing emitter resistor. I tried changing the current from 10 to 200 mA and also the two resistors at the top to no avail of making the modulated signal higher than 25uv. What is the problem? The gain should be merely 10.


texts: Is there a way to preserve EEPROM contents in AVR Atmega when burning a new firmware to flash with avrdude?

texts:
I'm finishing an application which will use some non-volatile parameters stored on an AVR Atmega644P EEPROM. The initial EEPROM values were generated using the EEMEM attribute (like described on this tutorial) and burned to the AVR using avrdude like this:

avrdude -c usbasp -p atmega644p -u -U eeprom:w:application.eep

The application runs and retrieves the correct EEPROM values, but if I upgrade just the firmware with avrdude -c usbasp -p atmega644p -u -U flash:w:application.hex the EEPROM seems to be erased too, for the values read are "all ones" instead of the previously loaded ones. So I ask, is there any way to burn the firmware to flash but avoid the EEPROM to be erased (using avrdude)?


texts:
as far as I know, always @* block is used in combinational circuit, and

the logic inside the always @* are sequentially executed regardless of the clock (asynchronous).

However, it seems that the logic inside always @* block in the below code

works synchronously according to the rising edge of the clock.

module univ_bin_counter
#(
  parameter N = 8
)
(
  input wire clk, reset,
  input wire syn_clr, load, en, up,
  input wire [N-1:0] d,
  output wire max_tick, min_tick,
  output wire [N-1:0] q
);

  //signal declaration
  reg [N-1:0] r_reg, r_next;

  //body
  always @(posedge clk, posedge reset)
    if (reset)
      r_reg <= 0;
    else
      r_reg <= r_next;
  //next statement

  always @*
    if (syn_clr)
      r_next = 0;
    else if (load)
      r_next = d;
    else if (en && up)
      r_next = r_reg + 1;
    else if (en && ~up)
      r_next = r_reg - 1;
    else
      r_next = r_reg;
  //output statement
  assign q = r_reg;
  assign max_tick = (r_reg == {N{1'b1}});
  assign min_tick = (r_reg == 0);
endmodule

Before I run the simulation, I expected that the syn_clr works asynchronously but it works synchronously.

Although the syn_clr is set at 90ns, the data q[2:0] becomes zero at the next rising edge of the clk.

If my understanding is right, it should be located in the above

always @(posedge clk, posedge reset)

block instaed of always @* block.

Could you explain what makes the always@* block executed synchronously?


texts:
I have ATMEGA328P-AU chip, to burn the bootloader I used ARDUINO Uno Board as "ARDUINO as ISP" with setup Board: Nanno. I'm getting the following error. While looking for the solution I got suggestions of

rechecking the connection - Yes I did
Lower the Buad Rate - Tried observed the same result as below
Tried varying the external oscillator 8MHz/ 16Mhz
The command to upload the bootloader is as follow:

  D:\WorkSpace\Arduino\arduino-1.8.7\hardware\tools\avr/bin/avrdude -CD:\WorkSpace\Arduino\arduino-1.8.7\hardware\tools\avr/etc/avrdude.conf -v -patmega328p -carduino -PCOM9 -b19200 -e -Ulock:w:0x3F:m -Uefuse:w:0xFD:m -Uhfuse:w:0xDA:m -Ulfuse:w:0xFF:m

I want to know the does this signature 0xffffff indicates I have blown out the IC similar ???

     Using Port                    : COM9
     Using Programmer              : arduino
     Overriding Baud Rate          : 19200 avrdude: stk50

  0_recv(): programmer is not responding avrdude: stk500_getsync()
  attempt 1 of 10: not in sync: resp=0x8e
           AVR Part                      : ATmega328P
           Chip Erase delay              : 9000 us
           PAGEL                         : PD7
           BS2                           : PC2
           RESET disposition             : dedicated
           RETRY pulse                   : SCK
           serial program mode           : yes
           parallel program mode         : yes
           Timeout                       : 200
           StabDelay                     : 100
           CmdexeDelay                   : 25
           SyncLoops                     : 32
           ByteDelay                     : 0
           PollIndex                     : 3
           PollValue                     : 0x53
           Memory Detail                 :

                              Block Poll               Page                       Polled
       Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
       ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
       eeprom        65    20     4    0 no       1024    4      0  3600  3600 0xff 0xff
       flash         65     6   128    0 yes     32768  128    256  4500  4500 0xff 0xff
       lfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
       hfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
       efuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
       lock           0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
       calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00
       signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00

     Programmer Type : Arduino
     Description     : Arduino
     Hardware Version: 2
     Firmware Version: 1.18
     Topcard         : Unknown
     Vtarget         : 0.0 V
     Varef           : 0.0 V
     Oscillator      : Off
     SCK period      : 0.1 us

  avrdude: AVR device initialized and ready to accept instructions

  Reading | ################################################## | 100%
  0.00s

  avrdude: Device signature = 0xffffff (probably .avr8x_mega) (retrying)

  Reading | ################################################## | 100%
  0.01s

  avrdude: Device signature = 0xffffff (probably .avr8x_mega) (retrying)

  Reading | ################################################## | 100%
  0.00s

  avrdude: Device signature = 0xffffff (probably .avr8x_mega) avrdude:
  Yikes!  Invalid device signature.
           Double check connections and try again, or use -F to override
           this check. avrdude done.  Thank you.


texts:
I have a small, simple circuit here. It doesn't work - both outputs (left and right side) are mute.

It uses the TDA7297 chip, and outputs 2 x 15W. I've wired 12V to '12V', and GND to -12V. I'm beginning to think that's the problem. Speakers need negative voltages as well... I've got a few LM337s laying around, should one of these be used to provide -12V?

If you need additional info, tell me.


texts:
My kids got a Talking Tom toy in a kids meal which they quickly discarded. It had a slide switch on the back and a button on his belly. With the switch on, if you press the button, he will say one of 4 phrases. Also, if you clap or talk loudly, he will say one of 4 phrases. I decided to take it apart to see how it works. I've included a photo of the entire circuit - minus the metal strips that were used as switching devices. It's two button cell batteries, an IC with 5 pins, and a speaker. I'm curious what kind of IC this is? It has markings on one side that read: 66-EE GA1E. I couldn't find any reference on those markings.

The pin that is sticking up in the photo is the pin that was 'activated' by pushing the button on the toys belly. When touched to the positive lead from the battery, it'll speak. I suspect that the speaker acts as a trigger (for loud noises). Does anyone happen to know what kind of IC this is?


texts: Is Deuterium arc lamp a AC or DC light source?

texts:
I have created a prototype photo-detector circuit to use in spectroscopy. The micro-controller code take 120 A/D readings and then returns average.
I have noticed that when I use visible light (normal 12v DC lamp), all 120 samples are same (some deviates by +1 and -1). However, using a Deuterium lamp, the samples are sort of rising and falling.
This is the snapshot of the values (Blue when Gain = 0 , Green when Gain = 4) from DC source lamp at 12V DC

This is the snapshot of values from Deuterium lamp (many samples to see the period)

I have noticed that when my Photo-detector circuit is exposed to normal AC light (India standard:230 volt, 50 Hz), then also I see some rising and falling pattern.
*I don't have access or understanding of Deuterium lamp supply.
*I have built a Monochromator to identify and seek to wavelength of my choice which detects the peaks correctly because of averaging.


texts: Esp8266-01 module attached to Arduino resets when DC motor runs

texts:
Machifit JT80SL DC 3-6V Water Pump: 3-6v
Servo sg90: 3-7.2v
Esp 8266 01: 3.3v

I have 2 Arduino Uno both has their own ac-dc power adapter.
Lets say, 1st Arduino is Ard1 and 2nd is Ard2.

The Ard1 communicates to a web server (BLYNK) with Esp 01.

Using I2C, Ard1 sends command to Ard2 to power/move the DC motor/Servo.

So far, it has no problem operating with Servo. But,

Whenever the Ard1 commands the Ard2 to power the DC motor.

Right when the DC motor runs(using digitalWrite(motor,HIGH)) the Esp 01 resets.

Tried using analogWrite(motor, 102) though it won't reset instantly, prolong usage randomly resets it anytime.
I also tried to test operating Servo and DC motor simultaneously in Ard2 using Serial commands, without I2C/Esp01. There was no problem at all, both works flawlessly.

Please, pardon me for the poor presentation. I have no solid knowledge on
electronics/electrical.

Below is the diagram of the wiring.


texts: Struggling to get an amplified sine wave over a small inductor at low frequencies

texts:
I am building a power amplifier circuit to amplify a sine wave over an inductor from a function generator. However because the inductor is small and i'm running at a low frequency I am getting concerning signals across it:

I have tried using a push pull amplifier but the signal is not much better:

I figured it was because of the reactance of the inductor that is causing this because when I increase the inductance or frequency I get an expected sine wave. So I created a parallel RLC circuit with the inductor and that brings me a sine wave however now I am getting little voltage amplification but if I remove the resistor then I get a current far too high.

I am wondering if anyone can think of a better fix because I am now getting no voltage gain and the inductor is already an auxiliary winding to drive a resonance circuit so I would like to not try and deal with another RLC circuit.

The signal across the inductor with a lower gain factor and smaller input signal:


texts:
I'm thinking of using a DAC as a precision voltage reference. I want 0-30V and would be happy with 12bit resolution although If i can get more I'd go for it.

My question really resolves around what DAC's will be best suited for this. DAC's typically run around 3.3V so I plan to use a opamp to increase this by a factor of 10x.

If I use a PWM DAC the noise/ripple would get amplified so that is out.

The use of a digital pot would be ideal although (as there is no noise) these typically cost more than a DAC though and have higher resolution.

I've seen a few audio DAC's around that have 24bits although I'm not sure if they will work with DC and what sort of ripple they might produce.

What DAC/type would you recommend?


texts: What would happen if I left the gate open in a self-biased JFET circuit?

texts:
In a self-biased JFET circuit, the gate voltage must be approximately zero so that the reverse voltage at the gate-to-source will be equal(but negative) to the voltage across the source resistance. This can be achieved by putting very large resistance at the gate so that no current will flow.

BUT, what would happen if I left the gate open so that the infinite resistance will block all current?


texts: what is the difference between using mosfet and bjt for op amp based current source

texts:
I have planned to design a op amp based current source driver for laser,but i came across two design one used mosfet1 at the output of op amp and other used bjt2 what is the difference

What is the difference between having the load in collector side2 and emitter side of bjt3 and will it be possible in case of mosfet also ie at drain and source


texts: VHDL: I have a lot of inferring latches due to my case statement

texts:
I have coded a project for an FPGA and in one of my files which is a mux, I have a lot of inferring latches, which I think is due to my case statement.
The code looks like this:

LIBRARY ieee;
USE ieee.std_logic_1164.ALL;
USE ieee.numeric_std.ALL;

entity twoplayermux1 is
    port
    (
        --inputs:
        show                 :  in std_logic;
        set              : in std_logic;
        input                : in std_logic_vector(7 downto 0);
        try                  : in std_logic;
        player               : in std_logic;

        --outputs:
        show_out             : out std_logic;
        set_out          : out std_logic;
        input_out        : out std_logic_vector(7 downto 0);
        try_out          : out std_logic;

        show_out2        : out std_logic;
        set_out2             : out std_logic;
        input_out2       : out std_logic_vector(7 downto 0);
        try_out2             : out std_logic
    );
end twoplayermux1;

architecture Behavioral of twoplayermux1 is
begin

process (show,set,input,try,player)

begin

case(player) is
        when '0' =>
            show_out <= show;
            set_out <= set;
            input_out <= input;
            try_out <= try;
        when '1' =>
            show_out2 <= show;
            set_out2 <= set;
            input_out2 <= input;
            try_out2 <= try;
        when others =>
            null;
        end case;

    end process twoplayermux1;

end Behavioral;

What could be the reason I get these latches?


texts:
For the most part, all solderless breadboards are alike. 5 or 6 contacts spaced 0.1" connected across, a gap (typically 0.3" wide), and 5 or 6 contacts more, and repeated x times down the other length (0.1" from each other). Some have rails on either end that are connected most of the way through.

My question is, does a breadboard without the center gap exist? I know there are ones with a wider gap (0.6"), but I have not found any without the gap. Do they have a different name?

My goal is simply being able to plug in a standard Dual In Line header without needing an adaptor, or modifying the breadboard (cutting out the middle, or cutting a contact set in half)


texts: Question regarding use of low voltage high current outputs

texts:
I see every day high voltage, high current; high voltage, low current. I rarely see low voltage, high current; why?

I know that I can take a high voltage, high current signal, send it through a step-down transformer and theoretically get a low voltage high current (with the same power output, of course), but I never see this done.

Can someone give me a reason as to why I wouldn't want a low-voltage high-current scenario?


texts: Using a DE-SW050 5volt regulator and a USB breakout board to charge an iPod in a car

texts:
I need a clean install of an iPod charger in my car. That means not a wire running from a 12 volt socket. I've looked at the Belkin flush chargers and they are beautiful, but require a socket.

I'm considering wiring one to a panel mount USB adaptor using a DE-SW050 voltage regulator. It'll take up to 30 volts (so 12 is trivial) and outputs 5 volts at 1amp max (iPad compatible). The wiring seems trivial: An in, and out, and a common ground. With a breakout board and the Cables to Go panel mount, (and a fuse in line with the 12 volts) this seems like a trivial solution.

Is it viable and device-safe? It seems like such a clean design that there must be a catch.

The other question I had was if it was possible to then add an LED to indicate that the 5 volts was being used. (Putting it in-line perhaps? But what about voltage drop?)

Help would be much appreciated.


texts: Sometimes the triac actuator doesn't turn off

texts:
The TRIAC actuator of a DC motor through a bridge rectifier.

I activate a DC motor from the mains through a TRIAC (BTA16) in series with a 10 Ohms resistor for the inrush current limitation, in series with a PTC thermal protection for the motor jamming protection and in series with a bridge rectifier needed to supply the dc motor with dc voltage, filtered by a 100 uF/400 V capacitor.

The TRIAC is triggered by a zero-crossing optotriac (MOC3043). The TRIAC is provided with a snubber of 100 Ohms and 100 nF. Hundreds of motors having this actuator have worked very well. It happened in some particular place that the motor once started didn't stop, but changing the place it keep working properly. It is the influence of the network of this particular place but I don't know which influence. I have added in series an inductance shifting the current with almost 30 degrees and the TRIAC worked very well.

Could some other inductive loads on this particular network have such a bad influence on the behaviour of the TRIAC? I mean a weak electrical network and some asynchronous motors around. Could you please give me any advice?

PS: I have attached a drawing but I was not able to post it. I hope that this description is good enough.


texts:
I'm working with SFH7050 chip, it contains 3 LEDs and a photodiode.
The datasheet suggests the next circuit:

But it doesn't mention how to calculate Rf nor Cf. Which values should I use and how are they calculated?
Also, the datasheet says:

Where should I apply the 5V?
thanks!!
Edit This is the waveform with Rf=100kOhms an Cf=0.1uF:

And this is what I get with Rf=10kOhms and Cf=0.1uF

something like the last one is what I'd expect since I'm placing my finger on the sensor trying to measure my heartbeats


texts:
Sorry for the stupid question but, I'm interfacing a PIC18f46k20 to an Atlas pH sensor module.  Both are running on 3.3v.  Must I use a max232 between or can the pic talk 232 directly to the module?

The reason I'm asking is it seems in the datasheet (pic) that the baud rate generator doesn't generate the 38400 required by the sensor board so I'm thinking the interface chip (max232) would correct for that somehow?  Using the formula on page 249, I'm running at the default internal 1MHz and I come up with a negative value for SPBRGH:SPBRG.  Or does the autobaud account for this?


texts:
I have two boards from the led headlights. Struggling to power it, I burnt one and now trying to understand how to properly power it.
Circuit itself looks quite straightforward: two upper LEDs are connected in series and connected to the pins 1 and 2. And bottom LED is connected to the pins 5 and 6. However I failed to turn them on.

I was trying to use different resistors in series with the LED but with no luck.
Eventually I connected it without resistor to voltage regulator and started to gradually increase the voltage from 2 V and above.

I used an ammeter to monitor the current. With 2 V voltage current was about 150 mA but no light form the led. Also I should mention that the board has a huge heatsink even though LEDs are only 3mm x 1.5mm. So step by step I increased voltage up to 12 V. Current was about 1.8 A (and heatsink was quite warm). But at some point I finished with short circuit inside the LED.

Appreciate any ideas about how to properly power this board

UPD: Also multimeter shows 0.7 V voltage drop on the LED. Is this normal? I thought typical voltage drop for high power LEDs is about 3 V.

UPD2: I replaced burnt LEDs with different ones and they work fine using the same power schema. My guess is that it somehow connected with LEDs themselves. They were 100% good and they are not IR. I don't understand why voltage drop on the LED is only 700 mV when for high power LEDs it's typical to have 3-4 V. So when I set voltage about 2 V (which is higher than 0.7 V) I have current about 200 mA already, but nothing happens. From my understanding it should start glowing event with 10 mA. Am I right?


texts: Slow-acting trage fuse unexpectedly blowing

texts:
I have a group of slave clocks which receive a brief pulse once a minute from a Raspberry Pi.

In case of the unlikely event of the pulse getting 'stuck' on and damaging the clocks, I mounted a Schurter 50mA slow-acting trage fuse in series with the clocks.

111mA of current flows through the clocks when switched on, and the fuse should last for about 2min. at this current according to the datasheet. However the fuse randomly blows after a few days of the clocks operating and needs replacing.

Does anyone have any ideas why? The pulses the clocks receive are about 1 second, much less than 2 min., and the Pi's logs show the pulses haven't been getting stuck on.

Thanks

EDIT: Here's a link to the datasheet: http://docs-europe.electrocomponents.com/webdocs/141c/0900766b8141c57c.pdf


texts: Handling RFID time response functions in C

texts:
I'm developing an embedded app, writen in C, using a M16C/28 uC from Renesas.

The app manages two simple task:

RFID for detection and reading MIFARE tags. ( Using HW: Mf500 from NXP ). The uC handles whole FW implementation.
To deal with a RS485 frame protocol as slave. ( This app, have to
be able to process RS485 frames every 10ms ).

I noticed that due to the RFID implemented blocking code, the time response to detect a RFID tag is about 15ms, so that's the reason because rx reception buffer overflows.

My questions are as follows:

Is it normal to deal with such time responses in the RFID world?
Should i use a RTOS to preemt RFID task to meet RS485 frames requierements? - Should i use an external uC acting as host controller to release the load of the RFID manager uC?


texts:
I have this questions:

At what frequency must a 4-pole motor be supplied so that its synchronous speed is
1200 rev/min?
The nameplate of a standard 50 Hz induction motor quotes full load speed as 2950
rev/min. Find the pole number and the rated slip.
A 4-pole, 60 Hz induction motor runs with a slip of 4%. Find:
(a) the speed;
(b) the rotor frequency;
A 440 V, 60 Hz induction motor is to be used on a 50 Hz supply. What voltage should be
used?
Why can an induction motor never run at its synchronous speed?
Choose suitable pole numbers of cage induction motors for the following applications:
a. a grindstone to run at about 3500 rev/min when the supply is 60 Hz;
b. a pump drive to run at approximately 700 rev/min from a 50 Hz supply;

I now the number of poles and slip formulas. Is there any other formula that could help me for this task?


texts: Very basic question about under damped oscillation frequency

texts:
Imagine a step response of a series RLC circuit oscillates as an under-damped way:

I also came across the following equation:

As far as I understand the ωd  above is the frequency of the damping oscillation (?) and ω0 is the resonant frequency which would be the oscillation freq. if the resistor was zero.

Is my way of thinking correct? If so what is ωd called in literature?


texts:
I have derived the stage 1 and stage 2 transfer function separately (both have their own feedback and schematics). I tried just to assume that the transfer function of the two stage as multiplication of both TF1*TF2.

My problem I don't know how can I get the full transfer function with the feedback coming from second stage output to first stage input through R1 as I don't know how I calculate the current flowing through R3. Is there a technique I can think of?


texts: How does Gunn diode generate oscilations?

texts: The Gunn diode can produce spontaneous oscillation if biased to the -ve resistance region of operation. How ? What exactly makes it tick ?


texts: Why we don't see adjustable "High" and "Low" Voltages for discrete logic gates

texts:
For single, discrete logic gate chips, why is it that we don't have adjustable types? The closest we have are those that vary along with voltage supply.

I suppose it uses a voltage reference in the chip. So why not have it be set externally? Medium voltage (power supply level) logic could be useful in some applications.


texts: Type of power converter to be used for both AC and DC use

texts:
What kind of power adapter that I need to use to supply power for a DC motor of a fan and also an AC heating element? These two components will also connect with Arduino.
Is any of these power adapter can be used?

Thank you for helping..


texts:
Sorry if my the answers to my question is just "look up the specs of CMOS", I wasn't able to find it, only data on the manufactoring process.

Doing research on a project, being new, I found a forum thread about someone wondering about some CMOS specifications. The numerous answers on this thread feel conflicting to me, excluded the "never leave unconnected wires" rule of thumb.

My questions then are : Are external resistances required for input/outputs/Vcc pins, or are there internal resistances ? If internal resistances are used, how much current are the chips designed for ? Does it depend on the chip itself ? Then what specification should I look for ? Why are there max current on output pins and not min currents too, if the internal resistances are huge (0, and x amps) ?

Sorry if it feels I just need a complete guide on CMOS technology, I wasn't able to find a good one, and sorry too if my questions are simply dumb.


texts: voltage regulators destroyed -- protection diode needed?

texts:
I have the following basic circuit:

As I was flipping the button to turn the relay on and off, I noticed sparking from the voltage meter, and it eventually caught fire, releasing the magic smoke which makes it work. On testing, it appeared that the 7805 was also destroyed.

I'm thinking that the relay was to blame here. Would adding a diode from ground to input help the situation? What else could I do to protect this circuit? (this is a controller driving an electric vehicle).


texts: How a current buffers works, I want to make (1-5)V to (4-20)mA V-I converter, how can I make this circuit load independent?

texts:
I want to make a 1-5V to 4-20mA Voltage to Current convereter. I choose this circuit. The circuit is working for only 250ohm load the conversion ratio is 4. But I want to make this circuit load resistance independent how can I do this.
V vs I plot as shown below graph.
please help.
Thank you.

I want to share some thing after this. I make some modification of the above circuit add got the the require current but as floating load. I want to make the grounded load with mentioned specification.


texts: BLDC Motor Constants: Why is my Kt and Ke different?

texts:
I'm new to working with motors. Reading up on BLDC theory, it is repeatedly said that in SI units, the Ke and Kt will be numerically equal. I downloaded the motor spec excel sheet of the T1101 motor by MTI. After choosing a particular winding and input voltage, it generates its motor data. As expected, the Ke = (30/pi/Kv). However, the Kt value displayed on the data sheet is different from the Ke value displayed. I'm confused as to the discrepancy. This is true both for peak and RMS categories.

Which brings me to my second point of confusion. Should I be using peak or RMS voltage/current in calculating motor performance? As a mechanical engineer, I'm trying to get a certain torque and RPM for some purpose. I look at a formula that relates torque and RPM to current, no load current, torque constant, voltage, etc. In these formulae, do I input the RMS or peak for voltages and currents?

I very much appreciate the help.


texts: Use MicroSD to SD adapter for read Memory Stick Micro M2

texts:
While searching in my personal affairs I found a Memory Stick Micro M2 (Sony) which I believe I was using in a phone. Unfortunately I no longer have the adapter that goes with it and it does not have the same format as a MicroSD. My goal is to use a MicroSD to SD adapter to try to read its content. Here is where I am in the material analysis.

The original adapter seem's to look like this

Is the pin identification correct and can I use this scheme to get to read the data or will it not work due to protocol, required supply voltage or other ? Thank you for your help.


texts:
I have this cheap DC power supply.

Tekpower DC Variable Power Supply, 1.5-15 V @ 2A, HY152A

It says it is limited by 15 V or 2 A. My question is, if I short it out, can it damage the unit? Is there anyway I can hurt myself with this?


texts: Initial current value in capacitor charging circuit

texts:
From this video lecture how come the initial current values are different in two cases?

I think they're assuming that the switch resistance is small in the first case.
However how about if they're the same switch and hence same resistance, just different capacitance to make one slow switching and the other fast swtiching?


texts: Why do all the LEDs in this circuit light up at once?

texts:
I have two things to say before I ask my question:

I am a layman with very little theoretical understanding of electronics (my question text will prove this, trust me). Sorry if my idea of the problem is a weird mess.
Coming from StackOverflow, I know that asking a question about such a specific scenario/problem may not add much value for others. I really just need help understanding what's going on here and I hope there is some general understanding in the end that might also help others.

What I want to achieve
I want to build a little box, exposing three rotary dials (or potentiometers in my case), each controlling the brightness of one channel of a single RGB-LED (common ground).
What I have tried
I bought three simple PWM-Modules (link to the product page for reference, not a referrer link!), each providing a potentiometer and +/- connections for the DC in and "motor" out (they're primarily meant for motors). I don't have the schematics of those, so my sketch below shows an abstraction of the modules. I also bought a little RGB-LED module that's nothing more than the LED and three resistors (pretty superfluous).
Here is a plan of how I prototyped my build:

The problem
For me (as an absolute layman) this looks like it should work. But the problem is that as soon as I turn up one of the PWM pots to control a single LED (of the RGB LED package), all three LEDs light up (nice and slow, so at least that works).
When I disconnect two of the LEDs, only one works (obviously). When I measure the voltage on the disconnected "out +" (from PWM out + to the LED) - all three get the same voltage. How is this possible? I want to control the RGB colors independently.
Is it possible that the PWM modules are not made to work in such a parallel configuration? How can I solve this? Thank you in advance!
PS: I know so little I don't even know how to correctly tag this question :(


texts:
I have heard that mosfets can be converted into resistors if they are "depleted". Can somebody explain how this is done as simply as possible...I don't have an EE background.

Thanks


texts:
The video processor (VDP) has 6*Fsc (21,47727 MHz) clock inputs, pins XTAL1 and XTAL2, which is inversion of XTAL1. Present circuit is built using quartz oscillator of above mentioned frequency, and 74HCU04 - and this circuit functions very well, outputting CMOS levels @ supply of 5V.

I am building encoder for S-video/composite, and it needs frequency of 4*Fsc (14.31818 MHz). Making another clocking circuit at this frequency introduces the problem of synchronizing VDP frequency and encoder's frequency to eliminate dot crawl and other artifacts. The best way to proceed must be obtaining 4*Fsc from the same master VDP generator.

I investigated a number of circuits to divide by 1.5 - e.g. this one (pages 9-10), and this one. Both are expected to work well in general, but fail in the following conditions:

if propagation delay through inverters/gates is comparable to 1/2 of the frequency half cycle, they introduce glitches;
while they keep overall frequency, two adjacent pulses' rising edges are not exactly at the distance of /1.5 of the master clock - and no documents state this, they state that their output is not 50/50 duty cycle, but not that their operation is not exactly /1.5 at the micro-scale. My encoder's datasheet states "The duty cycle of this input clock is not critical, but a fasted-edged clock should be used to prevent excessive jitter in the timing", and I am afraid 15 nanoseconds of the clock spread (@ 69 ns for whole clock period) may cause encoding problems, and thus deteriorate the output picture on the display device.

The part of the circuits I referred to, performing /3 clock division, seem to form very well timed rising edges in respect to adjacent output clocks, and I am looking forward for using it. But for this I need master clock to be twice than current - 42.95454 MHz. Then I will divide this clock by 2 to feed the VDP, and by 3 to feed the encoder.

The fundamental problems I am facing are:

I can not build the generator at this frequency using 74HCU04, as it is not up to speed. I can use something like 74F04, with this chip producing TTL output rather than CMOS. It may be an issue because VDP's specification for XTAL input for high level is minimum 3.5 V. The pro of this implemenetation that I may have trimming cap to adjust frequency for normal operating conditions.
I can build generator using 42,95454 MHz full size clock generator. I have found one source to purchase these generators, and it seems frequency is not that popular - did not find such on Digikey or Mouser. The con of this solution is that its frequency is not adjustable, spec for the device says 50 ppm, which gives 42,95454 * 0.00005 = 2147 Hz spread, and spread for VDP clock (/2) will be 1074 Hz and for encoder (/3) will be 716 Hz. This sounds too much out of the NTSC spec - most video tuning manuals state that spread must be maximum 20 Hz deviation from the 3.579545 MHz, thus for 4*Fsc must be within 80 Hz.

From your experience, what route must I go? Try to find 5 ppm full size clock generator (do such exist at all)? Use faster CMOS chip with circuit having trimming cap to adjust freq? Or maybe I still can keep original 21.47727 MHz clock and divide it to 1.5 somehow other ways I cited above?


texts: How to design a circuit starting from a block diagram?

texts:
I am struggling with the following self-study problem, taken from The Analysis and Design of Linear Circuits (8th edition).

There are two things that shock me from this problem.

We need to get a higher non inverting gain for the operational amplifier than the inverting gain. For me, this is hard to grasp because if the inverting gain is \$K = -\frac{R_2}{R_1}\$, then the non inverting gain will be \$K = a*(1+\frac{R_2}{R_1})\$, which is always lower than the inverting gain because a is a coefficient that can be added through voltage dividers (and thus \$a<1\$).
How can you only have one operational amplifier, yet still get an amplification of -3 after the operational amplifier and before \$v_0\$?

Any guidance is tremendously appreciated. The book does not explain this at all and I am just a very confused student.

Edit:

The transfer function I computed is:
$$V_A=5V_1 -V_2+V_0; V_0=-3V_A$$
$$V_0 = -15V_1 + 3V_2 - 3V_0 \Rightarrow V_0 = -3.75V_1 + 0.75V_2$$


texts:
I have an old CD-burner (HP 9100 plus) where I would like to control the BLDC motor from.

My idea is to use the original IC of the burner as the driver and use an ATtiny13 for controlling it. There are however some problems.

I found out that the IC is similar to the LB11699H datasheet, only lower model.

When I hook the CD-burner up to the power the motor spins up and down by itself a couple of times and then stops. I disconnected the cable to the laser head for safety. During the time the motor spins I can make it stop and spin a bit faster by changing pins 1 and 2, but when the motor is stopped by the on-board circuit, I can do nothing... I don't get the motor spinning. What is going wrong?

Also I need to have an analog signal between 0 and 2 volt to control the IC. Can this signal be generated with a smoothed PWM from ATtiny13 or do I need to use something else? Perhaps two batteries with voltage dividers and transistor connect to ATtiny13 pins? How do I do this?

Could someone help me out here? :D


texts: Can a 110v spa pump curcuit control a 220v spa heater that is on it's own 220v circuit?

texts:
I have a 110v spa pump that is itself controlled (on/off) by an air switch. I want to install a spa heater that is 220v, but when I purchased the heater I didn't realize that the heater should only come on when the pump is on. In other words, if there is no power to the pump then there is no power to the heater.
I have been told that it MAY be possible to control the 220v heater (with it's own dedicated 220v curcuit) with the power from the 110v pump.
How can this be done???

Although the truelly correct answer may be to get a 110v heater to pair with my 110v pump,
I like the idea of having the lower operating costs associated with using 220v.
Am I on track?
Or could a flow switch be used instead so that when the pump is off, it will "lock out" the heater? If so, is there any need for a t-stat? Seems like, no.

Al


texts:
I'm a beginner in electronics from the software industry. With some self-taught things, I'm trying to implement some basic Arduino circuits. My confusion is about capacitors mainly. My understanding about capacitors is that they act as power storage for few seconds or milliseconds.

I found that most IC's must have capacitors connected to their pins.

My confusion is how to find out which pins need a capacitor, and how to find the correct capacitor for a circuit or a capacitor for an IC.

Finally, why are capacitors necessary in a circuit in such situations?


texts: Stepper motor torque constant and electrical constant

texts:
I'm stuck with a problem regarding hybrid stepping motors and I'm not sure where I'm wrong.
I can't reconcile the torque constant with the maximum speed of a hybrid stepping motor with the following nameplate:
Holding torque = 9 Nm
Rated current = 10 A
Steps/rev = 200
Rated power = 40 W
The problem, in short, is this. The torque constant of this motor is 0.9 Nm/A, which (give or take some possible coefficients due to the multiphase nature of the machine or to the sinusoidal nature of the back-emf) is also the voltage constant in V/(rad/s) that yields the back-emf given the speed. The data sheet also gives the torque/speed characteristic: with a 24 V supply, the maximum speed is 6000 pps. With 200 steps/rev, 6000 pps is 30 rev/s, or 188 rad/s (mechanical). Now, if we multiply 188 rad/s times the voltage constant of 0.9, we get 169 V! How on Earth can a motor run on 24 V when its back-emf is 169 V? It should never be able to reach such speed.
I tried to write this off as a mistake in the data sheet, but then all the data sheets from this manufacturer must be wrong. Moreover, I found another data sheet from another manufacturer with the same problem (too high maximum speed given the supply voltage and machine constant).
What am I doing wrong? Thanks in advance to anyone who can shed some light.


texts:
So i've searched around the site, and there have been some questions about Capacitor shelf life and it being a somewhat sensitive components.

But are there any other "Lower" life components that someone would need to be aware of (Both Shelf life and "In Use" life, or whatever you would call that).

I figure Capacitors would be sensitive and relays (since they have moving parts) but what else?
and wouldn't a ceramic capacitor generally last longer than a Electrolytic?

-Also as an Add-on, is there a site listing or something with a "Average" lifespan of the most common components (Resistors/LEDS/Caps/etc)?


texts:
My application is a small robot-ic head - lets say for a scarecrow. It is going to be moved around frequently, during operation too.

I obtained a lot of these "hobby" servos that are used in RC planes/cars/helicopters...

My problem begins here - when I tried to fabricate the head using the design I had in mind, the model came out heavier than I expected.

Now on paper these motors (TowerPro MG996r CLONES) have good torques, but I want to believe during operation they might burn out and I will be left with a dummy head in one hand and resignation in the other.

So I thought I will use 2 motors for one axis. The motors will have to be coupled but at the same time facing each other - which means they will have to run opposite to each other.

I am thinking of using some aluminium couplings on one of the motors to reduce backlash. Software will have to be modified to (as close as possible) send opposite signals to both the servos... so that their torque actually helps each other.

Now for my question: Does this all make sense? Or is it not possible even theoretically? Is it a stupid idea?

P.S.: I am using a Pi-zero W (ABSOLUTELY LOVE IT) and a PCA9685 servo controller board (clone again :( ) - for information.

Thanks a lot O' lovely forum. I am getting entertained and educated going through all of the posts, hope to contribute soon.


texts: Determining command constants for serial protocol design

texts:
It seems to happen fairly often that I'm working on a system that incorporates a serial (SPI or async) command set.

As such, I generally have to put together a set of arbitrary command byte values that represent possible commands.

As such, I seem to find myself trying to maximize the distinction between possible commands. For example, If I have a grand total of 4 commands, I would choose something like:

 0x81, 0b10000001
 0x42, 0b01000010
 0x24, 0b00100100
 0X18, 0b00011000

or better yet (as it allows further expansion)

0xA5, 0b10100101
0x5A, 0b01011010
0X99, 0b10011001
0x66, 0b01100110
0x96, 0b10010110
0x69, 0b01101001

Both have the advantage of being both very distinct, so noise has little chance of corrupting one to look like another, and also being possible to (manually) determine the command using only a single logic-analyser or oscilloscope channel.

So, given the assumption that you are designing an arbitrary protocol, and the assumption that noise isn't a significant consideration, What is good advice and/or comments about the best way to choose binary constants for the command definition of a serial interface?

Actually, this seems pretty broadly applicable to any situation where you are using binary commands between two (or more!) systems.


texts:
I am trying to build a 5V constant 3A DC circuit. As stated in this datasheet: http://www.ti.com/lit/ds/symlink/lm338.pdf on page no.15.

According to calculation R2= 1.28 ohms, but I don't have it I have 1.6 near to it.

I have created the circuit using R2=1.6 ohms resistor and placed a 1K resistor as load and checked the voltage across it, it is giving me 15.68V which is a problem.

How can I accomplish this?

As stated in this datasheet: ti.com/lit/ds/symlink/lm338.pdf on page no.12. I have created the circuit and it is giving me 5.1 V constant just want to ask for confirmation that current drawn through this ckt will depend on load right? and we can take out max 5A right?


texts: Is there a cheap alternative to AVRs that can run the .Net Micro Framework?

texts:
Recently, I purchased a FEZ Panda and I've done some pretty cool stuff with it. Well, cool to me anyway. I recently had some ideas for things to do with LEDs and wanted to share them as kits. I see a lot of such kits utilizing small, cheap processors like the ATTiny13 or ATTiny85. Makes sense if it's just doing one thing with a small circuit that's simple. But I'm now hooked on using the .Net Micro Framework and love the fact that I can do everything from Visual Studio. For these little kits, I'm not opposed to using an AVR chip and writing in C, but was wondering if there was a .Net-enabled alternative. I've found some ARM7/ARM9 processors for around $5, but their package is rather difficult to solder onto a PCB for something as basic as a learning kit. Arent there any other form factors or other cheap alternatives that can be programmed using .NET MF?

EDIT: I'll also point out that there exist AVRs that come preloaded with the Arduino bootloader and they're cheap. These are also good chips to program with a single purpose and ship them with kits. I can't find a .Net MF enabled chip that I can do the same with.

Thanks in advance...


texts: I‘m trying to understand exactly what an L-section Network does. I understand it tries to eliminate the imaginary part of the impedance and match the real part. However I do not understand what excatly both components do and why the inductor(in my example, more specifically in a Highpass Downward L-match) has to be a shunt inductor and the capacitor has to be in series? Thank you for any help.


texts: PCB Identification - Many relays, 2 LM2596s, and other power-related components

texts:
I'm looking at a board lying around in my home and have no idea what it is, expect for the fact that it appears to be power-related. There's a transformer in the corner, many relays, 2 LM2596s, and a rack of 2N6039G transistors in the right corner.

Pics are below.

Right click and select "View Image" to enlarge images.


texts:
Can I charge my 1800mAh battery with 450mAh?

My 1800mAh battery is for my smartphone, and Im using a 9V niMH battery 450mAh  to charge it. Basically, I used a regulator to make the 9v input to 5v output.


texts: I just want to broadcast a simple Bluetooth message to an iPhone, no pairing or bidirectional anything. Do I need a full featured Bluetooth module? Or can I just use a microcontroller and an antenna?


texts: Three level PWM modulator circuit feedback simulation

texts:
I'm trying to design a three level PWM circuit with feedback and i'm struggling to understand the feedback aspect.

The design is based on this design by Texas instruments and modified to suit three level.

The design works if B is not added to the feedback loop.

As soon as i connect B to the 10k resistor, the circuit completely deteriorates.

I'm certain I don't understand feedback properly and am hoping someone can tell me what the issue is here or can direct me to relevant feedback literature.

The PWM is for a class D amp and i'm taking the feedback before the switching stage currently but intend to take pre filter feedback later on. Am I okay in assuming the feedback in this circuit is a good indication of what it would be like in a full amplifier circuit minus the switching error?


texts: How do I decide the resistance of a DC solenoid valve?

texts:
I am designing a circuit for a solenoid valve from BIO-CHEM. My product number is 075P2N024-02SQ. I want to know the resistance of the valve in order to decide how big a resistance I should use in series. Here is the printscreen of electrical chart.

I use "Power:2.8w" and "Current:0.1 amps"to get one value of resistance: 280 ohm.
I use "Voltage:24VDC" and " Current:0.1 amps" to get one value of resistance: 240 ohm.
I use "Power:2.8w" and "Voltage:24VDC" to get one value of resistance: 205.714 ohm.
I use a ohmmeter to get the value: 213.6 ohm

Which one should I believe?


texts: Identifying a schematic file and converting for use in Altium

texts:
I have a few schematic files which I need to open up in Altium, they are all *.sch files and when opened in Altium appear completely blank.
When opened with a text editor they do appear to have all correct information in there.
I have attached a small snippet of the file, but can upload one if required.
*P GCS_LTD
4 60 00000000
-3475, -1150, 4792, 4696, 25;
*R LASERNAV
*S4520B
550 500
1,5,150,50,150,450,400,450,400,50,1,5,
150,350,232,350,232,150,150,150,1,5,232,250,
272,250,232,280,1,5,150,50,400,50;
7,2,150,250,
3,2,150,200,
3,2,150,100,
4,0,400,300,
4,0,400,250,
4,0,400,200,
4,0,400,150;
;


texts: Why FPGA's have latches when they are almost never used?

texts:
This question is a follow up question of the existing question: "When is using latches better than flip flops in an fpga that supports-both".

If use of latches in FPGA's is limited to rarest or rare situations, why do FPGA's have latches at all ? I mean most FPGA designs don't use it. Then why have waste FPGA hardware for such logic!


texts: Simultaneous sampling of several channels with single ADC?

texts:
I am looking at this 8-channel, 18-bit and 200 ks/s ADC.

The datasheet claims the sampling is done simultaneously for all the channels, but the diagram shows that there is only one ADC, so how is this possible?


texts: How to detect unknown circuit button press without interfering with circuit

texts:
I have a membrane keypad in my dental chair where part of the it’s logic system is burned. So one of the buttons I need, that turns on and off a head lamp, doesn't work anymore.

So with an arduino I already bypassed the original lamp circuit with a 10W led, so I can turn on and off the new led lamp with a separate switch, but I want to use the existing button on the keypad to do it.

I found the common wire (0V) (for all the buttons of the keypad) and the lamp button wire. There’s 5V DC when any of the buttons are not pressed and 0V when any button is pressed. The lamp button wire works normally. From 5V DC to 0V when pressed

I need to interface this button with an arduino to make it work again as it should.

In this circuit from my chair, I don’t have a common ground to share with my arduino.

So, is there a non-obtrusive way, maybe with an optoisolator, where it could sense when there’s a short or not on the original wires, and then I could interface it with an arduino?

Maybe something wired in parallel with these two wires that doesn’t affect the rest of the original circuit?

The other buttons from the keypad use the same common wire and the logic board from the chair works normally, except for the lamp. So I can’t separate both lamp wires from the original circuit.

Thanks for reading.

Ps.: If more details are needed or measurements made  I can do it.

Ps. II: I have edited the original question because my multimeter cables were not working perfectly.


texts: Can you calculate clock to output delay from setup time, hold time and the propagation delay of wires?

texts:
"minimum tCO = <shortest clock to source register delay> + <micro clock to output delay> + <shortest register to pin delay>" is what I found on this site  ( quartushelp.altera.com/15.0/mergedProjects/reference/glossary/def_min_tco.htm )

But if I have the shift register below,  with setup time = 2ns and the hold time = 1ns and time for propagation between wires = 0 ns. Can I also calculate the minimum clock to output delay by adding the setup time and hold time and propagation time = 2+1+0=3ns for each flip flop?


texts: How to solve this differential equation corresponding to the RL circuit?

texts:
When VT is under on-state, this function is set up:

  $$L\frac{di_d}{dt} + Ri_d = \sqrt{2}U_2\sin(\omega t) \quad\quad\quad\quad (1-1)$$

I can't solve this function :(

  The instantaneous moment when VT was into on-state, $$\omega t = \alpha$$ $$i_d = 0$$ this is the Initial condition of the function above.
  Solving the function and substitude initial condition into the solution, we got:

  $$i_d = -\frac{\sqrt{2}U_2}{Z}\sin(\alpha - \varphi)e^{-\frac{R}{\omega L}(\omega t-\alpha)}+\frac{\sqrt{2}U_2}{Z}\sin(\omega t-\varphi) \quad\quad (1-2)$$

  where
  $$Z = \sqrt{R^2+(\omega L)^2}$$

  $$\varphi = \arctan(\frac{\omega L}{R})$$

I tried to solve (1-1) and get (1-2) but got into a mess:

$$L\frac{di_d}{dt} = \sqrt{2} U_2 \sin(\omega t) - Ri_d$$

$$\frac{di_d}{dt} = \frac{\sqrt{2} U_2 \sin(\omega t) - Ri_d}{L}$$

$$\frac{1}{\sqrt{2} U_2 \sin(\omega t) - Ri_d}di_d = \frac{1}{L}dt$$

$$\int\frac{1}{\sqrt{2} U_2 \sin(\omega t) - Ri_d}di_d = \int\frac{1}{L}dt$$

$$\frac{\sqrt{2}\ln(i_d)}{2R\cdot U_2 \sin(\omega t)}+C_1 = \frac{t}{L}+C_2$$

And I got stuck... ㅠㅠ


texts: What happens if you only energize one pole in a 2-pole 240 V circuit?

texts:
I have an Intermatic pool timer box that has two 120 V poles. The LINE has two pins (Pin 1 = L1, Pin 3 = L2), and the LOAD side has two pins (Pin 2 = Load 1, Pin 4 = Load 2). Currently, I have two loads, a 1/2HP pool pump motor, and a salt chlorination controller. Both loads run on 240 V, two-wire. My question is, what would happen if only one of the Load pins became energized, while the other was not?

Since the two-wire configuration delivers 240 V to the equipment, I assume nothing would happen since the other wire would be open, and therefore the circuit could not complete. On the other hand, I worry about sending 120 V to the equipment which might damage it. Please let me know what you think. Thanks!


texts: how correctly disable wakeup pin in STM32f0?

texts:
We need to disable wake up pin in some time, during stm32f0 run. we have used

HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN1);

but it doesn't work. Should we do something else?

Any help would be greatly appreciated


texts:
What are the pros and cons of Low-Side versus High-Side relay driving concepts in an automotive environment?

The questions popped up when I was looking for an 8 channel relay driver IC for a automotive ECU project. It seems like there are more Low-Side driver IC's available, but what's actually the pros and cons from the ECU designer point of view?


texts:
I am considering to use Zener diode for over-voltage protection for a digital input pin.

The absolute maximum rating for the typical IC pin is given as from (GND-0.3V) to (VDD+0.3).

I can use Zener diode to limit voltage below VDD. However, the forward voltage of typical zener diode is 0.7V. which fails to limit low voltage to -0.3V.

My signal is 1MHz signal, and will It be safe to ignore since it is marginal difference and the duration is short?


texts:
In case someone already stumbled upon this issue I'd be glad about every advice.
So I have an STM32 that is connected to a BlueNRG-MS and I set everything up using the CubeMX. There I select the X-CUBE-BLE under Additional Software and generate my code.

In general everything works fine but now I'd like to change the default IFR configuration.
My problem now is that in my project I do have a bluenrg_utils.h which holds all the required function declarations such as

void change_IFR_data_config(IFR_config2_TypeDef *IFR_config, uint8_t data[64]);

but it seems like CubeMX only generates a bluenrg_utils_small.c where all the required implementations are missing (only what is already used in the STM example is implemented).
I can find bluenrg_utils.c in the web (e.g. here) but I'd like to understand why CubeMX doesn't generate this file in the first place.


texts: I have ESP32 and the popular dot matrix module MAX7219 8*8 module to interface. It is connected through SPI pins. After a sample word printing on the maxtix it shows garbage outputs. Is it happening due to the logic level issue? Because the dot matrix works on 5V and ESP32 has 3.3v.


texts:
So I have an ultrasound system operating in the 1-10MHz range:

Pulser -> Tuning circuit -> Transducer -> Tuning circuit -> Voltage amplifier

The goal is, I'm trying to optimize the tuning circuits to obtain maximum signal at the voltage amplifier, as measured by an oscilloscope.  So far, I've tried varying impedance matched and non-impedance matched tuning circuits, and what I've found is that the impedance matched circuits obtain the best results.  That is, when Zi=R-jX and Zo=R+jX.  The tuning circuits I'm using are basic L-match circuits.

What I'm wondering then is, do my experimental results that impedance matching obtains maximum signal fall in line with theory?  I'm aware that impedance matching creates maximum power transfer, but maximum voltage is when Zi=0 and Zo=inf, so I'm confused on why maximum power transfer obtains max voltage in my experiments.  I would have thought that the tuning circuit which maximized Zo in relation to Zi would result in maximum voltage.  In our system, the traces are short enough that reflections are not an issue.

An example circuit on the receive chain would be like this:
Transducer -> Tuning circuit -> Voltage amplifier input impedance
Which might look like this

simulate this circuit – Schematic created using CircuitLab

So then Zi is the series combination of the Rsource & 2 caps, and Zo is the parallel combination of L and R2.


texts:
I'm using a 40A 120VAC SSR to control a 10A resistive load.  It gets hot during use.  Is this heat associated with the switching, with the load current, or with the voltage?  And where does it come from?

(Please provide an explanation that can be understood by a trade electrician with little electronic engineering knowledge.)


texts:
According to Cree Inc Pulsed Over-Current Driving of Cree® XLamp® LEDs app note, driving LEDs with high current pulses can be performed as long as the following guidelines are respected:

  Based on the 1-KHz pulse testing we have reviewed in this application note, Cree suggests the following guidelines for pulsed current operations:

  For duty cycles between 51-100%, do not exceed 100% of the maximum rated current;
  For duty cycles between 10-50%, do not exceed more than 200% of the maximum rated current;
  For duty cycles less than 10%, do not exceed more than 300% of the maximum rated current.

Although these guidelines may hold true for Cree's XLamp LEDs, are they applicable to smaller signal (5mm) LEDs?


texts: HC05 Bluetooth Ping without losing connection

texts:
I am currently working with the Bluetooth module HC05 using a Teensy 3.2 board. I successfully established a connection between the laptop and the board using Bluetooth. I can send data from the board and read it on the laptop.

This only happens when I run a python script that maintains connection between the module and the laptop; when I close it, the connection gets lost (even though it is paired properly).

What I want to do is to ping the device, to know what the percentage of packet loss is. I do not know how to do it, as when I am running the python script, it does not allow me to write on the command line to ping it. Then when I stop the script the connection is lost, so the computer does not recognize any device.

Is it possible to maintain the connection while not running the python script, or perhaps ping it through the Teensy or through the python script that establishes the connection?

Many thanks.


texts: switch off circuit when below 0.7 - 1V - UVLO?

texts:
I would like to create a undervoltage lockout that switches off power from a low voltage section of a circuit when the supply is below 0.7 - 1V.

As I understand it, most very low voltage logic stops having defined states at 0.6V or so. Presumably this follows that a circuit that only switches on at above these levels will still have an undefined state at below these levels. In this circuit it may take many seconds to go from 0V to above 0.7V. During this period I would ideally like to prevent any power being used by the rest of the circuit.

Does anyone have any creative suggestions or pointers?

EDIT: Thank you for all of the replies so far. To clarify:

The circuit being cut off is also being powered by the same supply. I'm after a 'gatekeeper' circuit to stop power going to the rest of the circuit when Vin < 0.7 - 1V.
The rest of the circuit will use a maximum of 100mA @ < 1.8V.
Ideally it would be a high side switch (but can work with low side)
I also forgot to add (very important) - the 'gatekeeper' part of the circuit shouldn't use more than a few microamps!


texts:
I am designing an electric veichle controller for a University project. The motor driver receives an analog signal (0-12V) to adjust the speed. I use a digipot followed by a buffer to convert the digital signal of the controller to ana analog one. Now I need some way to enable an disable each motor independently. I thought I can achieve this by cutting the supply power off the Op-Amp, but I have no idea how. I think there is Op-Amp with a disable pin, but I cannot what the state if the output is when the Op-Amp is disabled and I tried to simulate it using proteus software but it does not seem to work at all, further more I couldn't find this kind of Op-Amp locally to actually try it out. I am interested to know what you guys think. I will attach the schematic below.
Edit: I also thought about adding a comparator and supplying power to the buffer from the output of the comparator. But think this could be unnecessarily complicated.


texts:
My son got a
quadcopter for his birthday, a "NiGHT LiONS TECH® X9 Flying Car 4 Channel 2.4Ghz RC Quadcopte Drone".

On the box, it says that it communicates at 2.4 GHz on the "100-200 band"; on the website it says:

  2..4 Ghz spread spectrum transmitter uses multiple frequencies across 100-200 band

What is the 100-200 band? Does this refer to 2.4 GHz + an extra 100-200 Hz?


texts: Gray coding for 8-triangular signal constellation

texts:
I'm trying to find the gray coding for the 8-triangular signal constellation below, but no matter what I try, one of the neighbors always has 2 bits differing.

For example, two of the neighbors for 000 in the lower right quadrant is 101 and 100,, but 101 and 000 differ by 2 bits.

Is there a Gray coding for such a signal constellation?


texts: Potentiometer value if i used it as voltage divider

texts:
I want to make a voltage divider using a potentiometer.
Will the value of the potetiometer affect anything or not? I mean, if I use 10k or 1k or even 100 ohm, what's the difference?

And also if I use the voltage divider as a power source, why its a bad idea?


texts:
I'm trying to design a circuit that would be fitted inside large plastic gloves. That when the gloves are cut the circuit produces a signal.

Currently I'm considering having a metal (probably aluminium) lining sandwiched within the gloves that would have its capacitance measured. I can do this buy simply having a tuned capcacitive touch sensor circuit kind of like this. So basically the circuit would produce high when the cut occurs. Though I don't know if this would produce the results I require.

Hoping for some possible suggestions on really how to detect when the plastic outer material is cut without using a processor as this will add overhead.


texts:
I am using a blue LED (InGaN) in a simple circuit to show me when my garage door is opened by looking through a window.
The door is usually closed and may get opened once per day for a couple of minutes but sometimes longer.
The LED will work for 1-2 months then stop.  I replace it and then the same thing happens.
The circuit includes a blue LED in series with a 4.7K Ohm resistor, a 120VAC/24VAC transformer connected to 120 VAC source, a normally-open magnetic switch that closes when the garage door opens, and a fuse. The picture included does not show the transformer or the fuse.
As far as I can tell, I am not exceeding any design limits of the LED including temperature.
Any ideas?


texts:
While male 4 pin fan headers are plentiful (e.g., here), I can't find a female version of it. I see lots of them on fan extension cables, but none that can be soldered to a PCB. Does anyone know a type number or some information to continue my search?

I guess I could use standard 4 pin square headers without the tab, but I prefer to use the 'official' Molex connector to prevent myself from applying 12V to the 5V tach line and for a more secure fit.

Thank you very much.


texts: Calculate transistor collector and base resistors values for driving LED with GPIO

texts:
I try to learn how to use a transistor and how to calculate the necessary resistances. Here's what I calculate for the moment. I do not know at all if I left properly and if my equations are good. I think the equation for R2 is not good. How should I go about it? I also learn to read the data sheet of a transistor. Any help is welcome. Thank you

EDIT: it's WORKING

using factor of 10, using β = 100, R1 = 55Ω and R2 = 1325Ω precisely using potentiometers ... The LED does light when I connect a voltage 3.3 V on the base of the transistor, success.


texts: Can I change a capacitor with one with a higher capacitance?

texts:
Hi I have just joined after lurking a lot because I haven't found an answer that was specific enough for me.

I have a Soviet synthesizer (TOM 1501) and it has some odd defects such as clicking noises and sounds disappearing. I want to replace the capacitors in the power supply (only 8) to see if it solves the problem. It consists of three different types of electrolytic capacitors and I can easily find the two (2200uF/25V and 4700uF/16V), but I am having trouble finding one with 70uF/16V.

So I know that you can increase the voltage without it being a problem, but can you increase the capacitance? If yes, by how much?

It would be ideal for it to be axial but as long as it is big enough it can work.

The capacitors that are in the power supply right now are the infamous K50 from the Soviet Union, which are notoriously bad.

Thanks a lot


texts: Measuring input voltage with 3.3V ADC MCU

texts:
I am designing my very first DC motor driver circuit. Right at the start, I want to be able to measure the input voltage to the system. The system supposed to work with external DC power supply from 12 to 35 Volts. I think it is possible to directly measure this range with the ADC of the MCU (it is an STM32) with ADC ref voltage of 3.3V. Is the divider circuit below enough?

Do I need to do any protection for the MCU pin? Do I need to add a series resistor in the path between this (VSENSE_IN) point and the MCU pin?

For example, if the divider gives more than 5V...the MCU pin input limit is reached and damaged...how can I protect it from over voltage?

How can I improve this?


texts: What connections do I make to this Through hole DC Power connector

texts: I'd like to have one of these on a PCB I'm designing but I'm not completely sure how it works. Can somebody please explain to me how to connect this power jack to my circuit?


texts:
I'm trying to design an efficient circuit that is able to drive 4 independent (ie, connected in parallel) white LEDs and to control their intensity independently as well, through PWM.
The thing is: most of the circuits I find were designed either for 3 "strings" (rows of LEDs), which is cool if you use RGB LEDs, or don't provide a way to control the intensity of each string.

Using multiple driver ICs, each one controlling a single row, would destroy the efficiency of the whole circuit.

The white LED I'm using: http://www.mouser.com/ds/2/311/LW%20Y1SG%20-%20Micro%20SIDELED-335725.pdf
Forward voltage (max): 3.6V
Current: 30mA

Also, two other requirements are: it should have low quiescent current (ideally < 1uA) and Vin(min) > 1.6V since the circuit may be powered by two alkaline batteries.

This is the first time I'm designing such circuit, so I'm very looking forward to hear some tips from those who have done this before.
Thanks in advance!


texts: Cleaning a PCB w/ w/ Isopropyl Alcohol - What Type of Deionized Water Should I Use?

texts:
I read a post on this sub-stack from seven years ago, which detailed exactly what I need to do.  I will be soldering some components on a laptop PCB, and I'll be using rosin flux.  Therefore, I'll be cleaning it w/ 99 percent isopropyl alcohol, which apparently, when it dries, leaves a residue behind.  Thus, I'll be using the DI water to remove that residue.  The only thing the post didn't mention was the type of DI water.
I looked elsewhere online, and remarkably, I couldn't find an answer.  I'm assuming that I'll need to use either Type I or Type II DI water, but I thought it wise to inquire.  Does the type make a difference, and is there a specific brand anyone recommends for this type of work?  Any help would be greatly appreciated.  Thank you.


texts: I have to describe the function of the circuit below which is a 2 to 1 multiplexer connected to a D Flip Flop and even though I understand their functions individually I cannot really understand what the whole circuit is supposed to do. Any help is appreciated, thanks in advance!


texts: How to move lot of items with one microcontroller?

texts:
How to build a project that move lot of objects like this one http://www.youtube.com/watch?v=go2mZnRPqnQ ?

Note : This question was different at the begining, but it was confusing and Anindo Ghosh spent time on doing an off topic answer. I changed the question so it fit the answer. Yes it's not the meant it's mean to be but this way it became usefull knowledge base instead of being wasted.


texts: Functionality of output stage of a cmos amplifier circuit

texts:
I have the following circuit and I'm wondering a little bit about the functionality of the output transistors M12-M19.

simulate this circuit – Schematic created using CircuitLab
I know that M1,M2,M6 and M3,M4,M5 are two differential pairs and I also think, that M19,M12 and M16,M14 redirect/combine the current from positive and negative input to one current.
What I don't fully understand, though, is the idea behind M13,M15,M17,M18. I believe, that the node connecting all four gates and the drains of M18 and M17 should always have a voltage exactly at the mean of M18's and M17's sources. So I was thinking, that M13 and M15 could be cascodes, with M18 and M17 being a self-biasing network.
Is this pretty much it or is there more to the eight transistors on the right?


texts:
I was wondering the safety of using non-RoHS parts for hobby projects. I already use non-leaded solder, but some of the parts I have are not RoHS compliant. How much would I, and my family, be exposed to lead for parts like resistors, if I were to handle them? How much lead is actually in these parts that I would be exposed to? Or are parts marked RoHS compliant to indicate they are able to withstand the higher heat necessary for non-leaded solder?

Thanks!


texts: Can current flow both ways through a transistor?

texts: Last night I was experimenting with and motors and transistors. I was testing out NPN and PNP transistors to learn more about how they work and how I can use microcontrollers to control the speed with PWN. I was having some issues, including the transistors getting very hot, but the most confusing part of the night was when I turned the transistor around and the circuit still seemed to function the same. I thought transistors allowed current flow in only one direction. Maybe I am wrong about this?


texts: Connected to Multiple Drivers Problem Verilog

texts:
After I synthesize it, the error occured like this:
Multi-source in Unit <BCDcountmod> on signal <BCD0<3>>; this signal is connected to multiple drivers.>Any solution? (Here's below my code)

module BCDcountmod(
  input Clock, Clear, up, down,
  output [3:0] BCD1_1, BCD0_0 );
reg [3:0] BCD1, BCD0;
//reg [3:0] BCD1_1, BCD0_0;
always @(posedge Clock) begin
  if (Clear) begin
    BCD1 <= 0;
    BCD0 <= 0;
    end
end

 always @(posedge up) begin
      if (BCD0 == 4'b1001) begin
        BCD0 <= 0;
        if (BCD1 == 4'b1001)
          BCD1 <= 0;
        else
          BCD1 <= BCD1 + 1;
      end
      else
        BCD0 <= BCD0 + 1;
    end

always @(posedge down) begin
      if (BCD0 == 4'b0000) begin
        BCD0 <= 4'b1001;
        if (BCD1 == 4'b1001)
          BCD1 <= 4'b1001;
        else
          BCD1 <= BCD1 - 1;
      end
      else
        BCD0 <= BCD0 - 1;
    end

 assign BCD1_1 = BCD1;
 assign BCD0_0 = BCD0;

endmodule


texts: using current limiting diodes instead of resistors

texts:
Most 3d printers have stepper motors that are rated for maybe 2-3 volts, but are usually driven at much higher voltage like 12 or 24 volts. It's possible since the motor drivers are current limiting - so apparently it's fine to run (at least some) electronic components at voltages much higher than what they are rated for so long as current is limited.

Now I heard of current limiting diodes.
While I don't fully understand how they work yet, I wonder if, instead of using a resistor to create a voltage drop when operating electronic parts from a DC source of higher voltage, whether it would be sufficient to simply limit current using a current limiting diode, and whether that would be more energy efficient / would result in less heat?


texts: Difference between [W] and [WS] power rating of resistors

texts:
I see some datasheets of power resistors where power ratings are in Watts [W] and some in [WS] which I don't know what they mean.
What is the difference between them?

Example of datasheet

Some screenshots from datasheets:


texts:
How do this two gate able to give an output if in the first place they both doesn't have a second output... in which will be the input of the other...

Both cannot get a second input because they don't have a second input themselves to provide an input to the other...

Conversation:

Gate 1: Hey gate 2, I'll give you your second input... oh wait, I don't have my second input... I can't provide you your second input.. you don't have a second input as well that I need, now we're stuck.

Gate 2: I know right.


texts: starter motor field coil wrapping material

texts: In my Land rover starter motor , the field coils are wrapped in cotton tape, I see that Egyption cotton tape is sold for this purpose, but I am told I can use rubber tape, will this interfere with any magnetic field? why did they use cotton tape?


texts: LTspice - Flyback simulation misunderstanding

texts:
I am trying to understand how to compute the rms current through the output diode of a flyback with multiple outputs. To make it simpler, I did not add the leakage inductance of each windings. Here is my schematic :

Here is the result of the simulation :

What I do not understand is why I(D3), the output diode of Vout1 take all the current from the primary when the voltage at the secondaries (across L4 and L2) is superior to Vout1 and Vout2. If it is the case the two output diodes should conduct as the voltage across the diode are forward bias. The simulation said that the two output diodes conduct when vout1= vout2 ??? Is someone is able to understand what is happening ?
I(D5) -> Vout2
I(D3) -> Vout1
Thank you very much and have a nice day :)


texts: Is 18650 battery capacity from 3V or 0V?

texts:
To calculate the battery capacity in mAh of an 18650 battery I understand you can use something like an iMax B6 in discharge mode on a fully charged (4.2V) battery to get the mAh it provides. The iMax B6 stops at 3V.

So my understanding of this is that the reading shown is the mAh that were provided by the battery going from 4.2V (or whatever it charged to) down to 3V.

I understand that running an 18650 Lithium Ion battery below 3V causes chemical instability and shouldn't be done. So what I am unsure on is if the value shown on the iMax B6 is the "rated capacity" for this batteries (the ones shown on the specs and printed on some batteries) or if you need to do some other calculation to get the full capacity of the battery going down to 0V?


texts: Driving strings of high power LEDs - different ways with fault protection

texts:
I'm trying to find the best method for driving around 30 x white LEDs plus 10 x RGB. The power supply can be 24V. The LEDs will be dimmable, 3W or 1W, 0.350A or 0.7A (I'd need to limit the current a little below the maximum.) Everything connected to the PWM driver.
I have been making buck converters, but this time I prefer something simpler and small to fit inside the lamp (<12mm height.)
I considered:

NSI-50350
LM317. If I calculated it properly it would waste less than 2W.
Better method? Simple and cheap. If it is not worth putting it inside the case I will consider an external box.

There is one more thing, I've seen somebody using a regulator - maybe an LM317. But he used two little 0805 resistors and he had an LED open and LED short fault detection. It would auto off the whole string or only a small current would flow. I can't find it anymore.
How can I implement it?


texts: Multiplexing a 74141 Nixie driver with a MAX7219

texts:
I'm building my first Nixie project where 8 tubes need to be driven with an Arduino (I've managed to drive 1 single tube). I found out this can be possible with multiplexing.
My question is, is possible to do 4 "channel" multiplexing with MAX7219? Is it possible to instruct the 74141 IC logical gates with MAX7219, 4 at same time? If so, how?
If this not possible, how to do it without transistors?


texts: I built this circuit and it seems to work if i use a the same power supply to the motor that is powering the IC.  I am using an LED in place of the motor for testing.  But the circuit does not work if i use a separate power supply for the motor(LED).  I am using a 12 volt power supply for the IC and a 9 volt battery for the motor(LED).  I am trying to control a 90 volt DC motor and plan to rectify 110VAC to power the motor.  My question is should I be able to power the motor with a separate supply?  Does the ground for the MOSFET need to be the same ground that the IC uses? I am using a IRF630 for the MOSFET.


texts:
I have need to detect when something around the house is switched on.

A simple example would be that if someone switched on a light i need to be able to track that on a computer.

It needs to be at it's very basic form, for example: simple cable connected to a USB port. if i connect a battery to the USB cable i need to be able to detect that.

I had a look at some of the USB specifications, but they all mention reading information, nothing on reading voltage input into the USB port. My next logical step, is to try and convert that voltage into something the USB might recognize, which i presume is transforming volts to bits.

Does anyone have a schematic of how to build something like this? i would prefer not to make use of a micro controller, i need the device to be as simple and cheap as possible.


texts: Overshoot/undershoot issues in load current wave form of a MOSFET

texts:
We have designed hardware circuit which validates voltage regulator maximum output current.
So we designed op-amp circuitry to control gate drive of the Power MOSFET and it will work in active region and pass the regulator output current through MOSFET. Here the Mosfet is our Load.

Issue: In our design we are capturing the output current wave form it shows the overshoot and undershoot in it. I suspect MOSFET input capacitance causing this issue. We have RC circuit for compensation to this but I need to understand this issue clearly and what are the possibilities causing the issue. Kindly help me on this

Attached is our op-amp circuit schematic and MOSFET design.

Sorry for delaying to upload the output wave form where I can see overshoot, undershoot in it (circled in yellow)


texts:
Complex voltage and current have clear physical meaning: they represent amplitude and phase shift of a sine wave.
I was wondering if complex impedance has any physical meaning as well. Can I plot it as a sine wave,or is it just a number that we are supposed to treat as a mathematical  abstraction without any relation to the real world?


texts: Is it possible to daisy chain smaller inverters to achieve a higher overall output power? For instance if I have a 48VDC battery bank and I want to power a large compressor at 240VAC it will need a lot of power. More then the inverters I have seen. So is it possible to connect inverters together to achieve the higher power in terms of KW?


texts: How to calculate the spectral irradiance of an array of LEDs?

texts:
Good morning, how can I calculate this equation?

The LEDs have the following specifications:
https://www.mouser.com/datasheet/2/143/EAILP05RDDB1-708504.pdf
_ 12 LEDs; 3 second exposure; 20cm distance
Thank you very much for the help.


texts:
First question is does our body actually generate current?

My guess is that it's a yes, we're technically a walking battery. I know that if I touch probes of a multimeter, we can measure some kind of voltage. It's usually not stable but there is actually something to measure.

I was wondering exactly how much current can we get from our own body. I remember I saw a video where a person touches his oscilloscope and said that the sinewave he sees is actually the current from the main that is capted by his body. Because in reality, the body is also a good antenna.

So what I really wanted to know, how much current can we get from our own body. Could that be enough to power small devices such as a watch or other kind of wareables.

If the body produce electric energy, is it affected by the body activity. For example, at rest we produce lest energy than while running.

Anyway, I'm pretty sure it is possible because EKG/ECG actually work by measuring heart's electricity.

Now if that was possible to power a device from our body's electricity. Would that be harmful? I guess we don't produce energy for nothing.


texts: connect LEDs to USB keyboard – but they turn off after a second

texts:
I have a USB keyboard. As I work many times in the darkness, I put some LEDs into the keyboard case. I connected two pairs of yellow standard LEDs serially to the USB power lines (Vcc and ground, pin 1 and 4).

  ┌───⊳|───⊳|───┐
⊕─┤             ├─⊖
  └───⊳|───⊳|───┘

Now when I plugin the keyboard the four yellow LEDs turn on for a second, begin to flicker and then turn off. The keyboard works, though.

Standard LEDs need about 20 mA, if driven at the correct voltage (2.5 V might be a bit to much, that means they possibly need more than 20 mA). So for two pairs of serially connected LEDs that would only be 40 mA (or maybe a bit more due to overvoltage — at least I am sure that they need more than 1,67 V, because if I connect three LEDs serially to the USB, they don’t light up).

Why does that happen? Does the keyboard possibly tell the computer that it doesn’t need so much current/voltage and then the computer cuts it down?

Update

I have just soldered two cables to a USB powered USB hub and plugged them together with a similar four LED array into a breadboard. And what happened: The LEDs shine and stay lit up for ever. Then I connected my modified keyboard with its four new LEDs. The four LEDs in the breadboard stay lit, but the ones in the keyboard turn off again after a second. The keyboard works. I am using it to type this. How is that possible?

I have measured current and voltage for the LEDs on the breadboard: The USB hub provides a voltage of exactly 4.2 V! A current of 19 mA runs through the breadboard LEDs. A little bit low for two LEDs in parallel, but I don’t need a resistor.


texts:
I am working with Artix 7 (xc7a15tftg256). When the time of Run Implementation,shows the following error message:

  [Place 30-574] Poor placement for routing between an IO pin and BUFG. If this sub optimal condition is acceptable for this design, you may use the CLOCK_DEDICATED_ROUTE constraint in the .xdc file to demote this message to a WARNING. However, the use of this override is highly discouraged. These examples can be used directly in the .xdc file to override this clock rule.
          < set_property CLOCK_DEDICATED_ROUTE FALSE [get_nets input_IBUF] >

input_IBUF_inst (IBUF.O) is locked to IOB_X0Y83
input_IBUF_BUFG_inst (BUFG.I) is provisionally placed by clockplacer on BUFGCTRL_X0Y30

For my application I check rising_edge(input). Kindly provide the solution in this problem.


texts:
I accidentally knocked a SMD electrolytic capacitor off the motherboard of an ASUS laptop I was stripping down to clean. It looks like the copper pad came off with one of the legs. So My questions are:

Am I likely to be able to repair this myself? If so, any brief explanation or links appreciated. Part of my problem is knowing how to ensure any replacement of the copper pad is connected to the circuit.

If I cannot repair, what effect is this likely to have? I have not been able to find a circuit diagram but the location is very near to the fan and heatsink and away from most other components. Probably a dumb question but, can I assume it is related to the fan operation? Am I likely to do further damage by attempting to use the laptop without a repair? Will it even work?

The final pic below shows another identical capacitor on the board. I have been told it is a tantalum capacitor 15uF 25v however I have not been able to source an exact replacement. Can anyone advise a suitable more readily available alternative.

Many thanks!


texts: How do I improve efficiency of a boost converter?

texts:
I have built a 3V to 5V boost converter with discrete components.

L = 220uH

Vf(Diode) = 0.25V

ZVN4210A MOSFET

C = 470uF

f = 47KHz

My load is a microcontroller board (M16C QSK62P Plus) that takes upto 90mA of current. I am using the PWM signal from the same microcontroller for the switching pulse for the converter.
I tested my circuit for a constant load of R = 100Ohm

I measured average current flowing through the inductor and output voltage.
From that I calculated powers Pin and Pout.

I am getting the efficiency of approx. 75%. I know that boost converters can be more efficient (90%). So, I need some suggestion about modifications in my circuit to improve the efficiency.


texts:
I am new to electronics.  Iam designing a simple circuit where I have to make a digital switch:

Here is what I have designed in Proteus:

There are 2 issues:

I want it to output 5V when I close the switch but it does opposite. It outputs five when the switch is open.

When switch is closed it gives 0.05 volts but I want 0V.

What changes should I make here?


texts: What is this cylindrical black component with a wire looped through it?

texts: Could anyone tell me what this component is? Thank you


texts: How to drive optocoupler with BJT properly [schematics]

texts:
Recently I asked a question about optocoupler:
Shematics: optocoupler controls a transistor and doesn't work as expected

I have one more question related to the topic. PWM input comes from the microcontroller Atmega88 and there are Q5/Q7 to drive optocoupler.  As far as I see the two schematics below are identical. Output is used to open power transistor that charge or not the battery.

What schematics should I use and what advantages and disadvantages of them?
Thank you

The first schematics:

The second schematics:

EDIT:

Thank you for all the comments, I'll try to explain the question more clearly:

1) PWM frequency is 10kHz, I may select any other PWM frequency because it's coming from the MCU

2) Full part name of the optocoupler than I use TLP181YE, there is no such part in Multisim

3) What I try to achieve:

I try to have OUTPUT (on the right) that connects to the base of power transistor FJD3076 (not presented)
The transistor FJD3076 controls the current that charges battery.
The intention is to gradually increase/decrease base current of FJD3076 using OUTPUT so I want TLP181YE output to change gradually (no PWM here)
PWM comes from MCU and after R21/C2 (R14/C1) there is a constant voltage (I may control it using PWM) that controls Q7 (Q5) and therefore TLP181YE and therefore FJD3076

UPDATE:

Based on very useful replies from Andy, Russell and Vovanium (Vladimir I guess) and experiments:

there is definitely a problem with trying to pass analogue signals through the optocoupler
I get rid of C2 and PWM altogether, I'm charging the battery with constant voltage, current limitation isn't presented in the schematics. Instead of PWM I will have steady 0 or 3.3V
regarding the positioning of the transistor, I stick with the first schematics

I'll experiment with the board more and be back with the final results.