texts: How to send out 60khz signal from antenna?

texts:
BACKGROUND

In Japan there are radio-controlled clocks. Time is synchronized by 40khz (in west Japan) and 60khz (in east Japan) radio, which is broadcast from transmission towers. The signal is known as JJY:

https:/ /en.wikipedia.org/wiki/JJY

After the earthquake in 2011, the tower in the east Japan was collapsed. Time synchronization in the east Japan is affected. Hence, someone Japanese has made a simulators and shared on the Internet.

I am from Hong Kong. I have a radio-controlled watch and clock bought from Japan. I want my devices to be synchronized. There are iOS and Android app JJY-simulators. I have tried some of them. This one works well:

https:/ /play.google.com/store/apps/details?id=jp.houryo.jjyemulator&hl=ja

The principle behind is, using time from NTP server, emulating the JJY signal, sending out through 3.5mm audio port.

Now I want to implement the emulator on a Raspberry-Pi. There are some tutorials found on the Internet. Below is the one I am following to:

http://itpro.nikkeibp.co.jp/atcl/column/14/093000080/093000002/?ST=oss&P=1 (Japanese)

Instead of the source-code in the tutorial, I use this one:
https://github.com/snt/rpi_jjy_server

PROBLEM

I have made the circuit following the tutorial:

However, most of the time my watch does not read any signal.
If there is signal, the signal status is "low", and eventually the time-sync is failed. (For the Android-app one, my watch can read a "high" signal.)

Note: I am using Toshiba 2SC1815-GR transistor, 30k ohm resistors, which are suggested in the Git-hub article. And a telephone-line made antenna.

I have tried using a 9V battery replacing the 5V Raspberry-Pi power source. But it does not help.

My knowledge on electronic is very limited. Please kindly forgive me if I have asked silly questions or made silly mistakes. Could anyone please point out if I am made anything wrongly? Or, by what means could I boost the signal from the antenna?

Great appreciation for any help!


texts:
I want to make a simple processing element for calculating the absolute difference between two 8-bit words. However, this element may be used as part of an array in order to speed up the AD calculation, by making it in parallel on more data. So, to achieve that, except from the two 8-bit data inputs and the one 8-bit data output, it should have another two 8-bit data outputs (let's name them SHIFT_A and SHIFT_B) that will hold the value of the previous inputs (like a shift register).

I tried to make an implementation in VHDL, but it's not working because I can't figure out how to make the two SHIFT outputs having different values than the two data inputs. I've tried many things without success so, I'm giving here my source code:

LIBRARY ieee;
USE ieee.std_logic_1164.ALL;
--use ieee.std_logic_arith.ALL;
use IEEE.NUMERIC_STD.ALL;

entity pe_element is
  port(
    --Output signals
    AD_o : out std_logic_vector(7 downto 0);
    SHIFT_CB_o : out std_logic_vector(7 downto 0);
    SHIFT_RB_o : out std_logic_vector(7 downto 0);
    --Input signals
    cb_en_i : in std_logic;
    rb_en_i : in std_logic;
    diff_en_i: in std_logic;
    clk_i : in std_logic;
    rst_i : in std_logic;
    CB_i : in std_logic_vector(7 downto 0);
    RB_i : in std_logic_vector(7 downto 0)
  );
end pe_element;

architecture pe_element of pe_element is

--Define FSM states
type statetype is (S0, S1, S2, S3);
signal state, nextstate: statetype;

--Signal definitions
signal adder_tmp: std_logic_vector(8 downto 0);

-- That particular hack is a pretty annoying one. Idiots.
signal am: integer;
signal bm: integer;
signal CBreg: std_logic_vector(7 downto 0);
signal RBreg: std_logic_vector(7 downto 0);

begin

-- Current State Register

process(clk_i)
  begin
    if clk_i'event and clk_i = '1' then
      if rst_i = '1' then
        state <= S0;
      else
        state <= nextstate;
      end if;
    end if;
end process;

-- Next State Logic

process(state, diff_en_i, cb_en_i, rb_en_i) begin
  case state is
    when S0 => if diff_en_i = '0' and cb_en_i = '1' then nextstate <= S1;
               else nextstate <= S0;
               end if;
    when S1 => if diff_en_i = '0' and rb_en_i = '1' then nextstate <= S2;
               else nextstate <= S1;
               end if;
    when S2 => if diff_en_i = '1' and rb_en_i = '0' and cb_en_i = '0' then nextstate <= S3;
               else nextstate <= S2;
               end if;
    when S3 => if diff_en_i = '1' then nextstate <= S3;
               else nextstate <= S1;
               end if;
    when others => nextstate <= S0;
  end case;
end process;

-- Output Logic
am <= to_integer(signed(CB_i));
bm <= to_integer(signed(RB_i));

CBreg <= CB_i when
        ((state = S1) and cb_en_i='1');

SHIFT_CB_o <= CBreg when
           ((state = S1) and cb_en_i = '1');

RBreg <= RB_i when
        ((state = S2) and rb_en_i='1');

SHIFT_RB_o <= RBreg when
           ((state = S2) and rb_en_i = '1');

adder_tmp <= std_logic_vector(to_signed(abs((am - bm)),9)) when
           ((state = S3) and rb_en_i = '0' and cb_en_i = '0' and diff_en_i = '1')
           else "000000000";

AD_o <= adder_tmp(7 downto 0) when
           ((state = S3) and rb_en_i = '0' and cb_en_i = '0' and diff_en_i = '1')
           else "00000000";

end pe_element;

As you can see in the following simulation image, the SHIFT output holds only the new value each time, and not the previous one.

I'm pretty sure I've coded something wrong, but I can't find it. Do you have any ideas?


texts: Buck-Boost converter - Boost mode not working

texts:
I am using TPS63001 Buck-Boost regulator for creating 3.3V in my circuit. The converter works in Buck mode as excepted. So when I give 5V on the input, it is OK. When I reduce the input voltage from 5V to 2.7V, it still works perfectly in this case in Boost mode. But when I turn the input voltage off, and try to start the circuit from 2.7V, it does not work. It consums ~200 mA current, and gives a buzzing noise out, the output voltage is not 3.3V

My circuit schematic is following:

The EN is connected in this case to VCC. I tried to change the inductor, but the same effect is shown. What could be the problem?

EDIT

I measured the EN input voltage, and it falls to ~1.6V, so the chip can't turn on. The VCC is created following:

The Forward Voltage of the Schottky diodes are maximal ~0.4V. So if the system gets 2.7V, the VCC should be at least 2.3V, but it falls down to 1.6V. If I use a wire to connect 2.7V to EN directly, the konverter turns on and remains turned on when I remove the wire.

The layout is OK, I followed the recommendations in the datasheet. There is currently no load on the output, because I want to solder up the microncotroller, when the power supply is stable. The chip should be fine, because I have 2 boards with the same chip and same layout and the same effect is shown. Can the Schottky diode be problem? There is 1V droping on the diode, if the regulator is working fine, than it is ~0.35V.

EDIT

The layout is following:

The C1 is close to the Vin.


texts: How does the delayMicroseconds() function works. From what I understood the prescaler of timer0 is set to 64. For a 16MHz clock gives 4.0uS per count. I am a bit confused on the math to get to 1uS interval?


texts:
I am trying to simulate a Buck-converter circuit in Orcad, but no matter what I change the input voltage to I still get the same output voltage result. I tried this in Multisim and got the same issue. why is that happening? I have attached a picture of the schematic of my design it's just the basic buck-converter circuit and the values are calculated by hand from a question in my power electronics book.

according to the duty cycle, my output voltage must be 25% of the input voltage so I must have 25V at the output but I am no where near that. I tried using different load values with similar results.

EDIT: The simulation type is transient time it is set to run for 2 seconds.


texts: How do you find rO when solving this differential amplifier?

texts:
gm could be determined using Jacoletto (40*Ic, where Ic was found while solving the bias point)?

Some of my attempts at solving the circuit


texts:
So I'm using the an Arduino (Mega 2560) to control 9 little 12V solenoid valves (Gem Sensors) and my plan is to connect the Arduino to some small solid state relays (Broadcom Limited ASSR-1511-001E) which will be connected to a 12V power supply which will actually power the valves.

Anyway I am curious if I need to put any resistor or safety mechanisms between the Arduino and the SSR. Judging by the various data sheets it looks like I can directly connect the Arduino digital I/O pin to the SSR and just connect the 12V power supply straight to the SSR and have the solenoid valve connected to that circuit. The Arduino puts out 20 mA on the digital pins and the SSR can take up to 20 mA. Is there anything else I need to consider here?


texts: How to connect male wire to stiff piece of metal with holes

texts:
This is my second day playing around with Arduinos, so I don't particularly know hardware-related concepts and terminology. I'm trying to connect a simple male wire to a button (see image). The only thing I've tried is simply threading the hole with the pin, but that clearly doesn't work.

I haven't found any other solutions since I'm not sure how to refer to the shape in question. I did purchase an Arduino kit, not just the Uno, but this was an external part so I wasn't able to find any instructions. Any help would be greatly appreciated!!


texts: Convert from 4 bit binary number to 2 bit binary number

texts: I am currently using logisim to output a 2 bit binary number, however, the bit adder releases 4 bit binary number instead. Is there any way to fix this? (I am currently using v 2.14.6 .)


texts: Boost regulator: Unexpected output voltage

texts:
I just finished setting up an LM2577 as a boost converter, and have run into some unexpected issues.

For starters, here is the recommended "typical application circuit":

My application circuit is slightly different. At the 5V input, I can actually have anything between a 8V to 14V input as part of a PMOS common source setup so I can turn off the current coming in to the circuit, like so:

However, the output voltage is nothing like what I expected. I had assumed that if I'm drawing at least a few dozen milli-amps, and have a +9V DC rail at the source of the PMOS, I should expect just under 9V at the drain of the PMOS when it's turned on, and that the output voltage of the boost regulator, Vcc, would be approximately 12V. My assumption was also that the output voltage is just a function of the external discrete components connected to the regulator, and not the input voltage (ie: 9V DC) provided the input voltage to the regulator is less than the output voltage it generates. Is this assumption correct? I want the regulator to always output a fixed voltage (ie: 12V) for a wide range of input voltages (ie: 7.5V to 10.0V).

Also, the output voltage I initially measured was much greater than expected, a whopping 41V. When I removed the 0.1uF capacitor that connects the input to GND, it went back down to +15VDC. How can this be happening? Is it because the input to the regulator is from a PMOS drain and not a supply rail?


texts: How do I safely discharge a 3900 pF 3 kV (and 9 kV) capacitor?

texts:
I am planning to built a circuit with 3 polypropylene film 3900 pF 5% 3 kV DC radial capacitors connected in series. Before I start this, I want to make sure the capacitors are safely discharged. I am also thinking that I will need to safely discharge them after they are soldered together. I tried researching this and found a site on Digikey to calculate what size resistor should be used, but found that it would allow any ohm value based on time:
Digikey: Capacitor Safety Discharge Calculator
What would be an appropriate resistor for safety discharging these capacitors?  I am not concerned if it takes a while for it to discharge, I just want to make sure I do not choose one that is to small for capacitors of this size.
Thank you.


texts: How to apply HT gradually in a valve amplifier?

texts:
For valve amplifiers, it is said, that applying anode voltage before the valve is heated reduces lifetime and can have other negative effects on circuit lifetime.

To avoid this, I want to add a thermistor to the HT voltage line, so the valve has time to heat, and the HT is applied in a more controlled manner.

Based on what parameters of my circuit should I choose a thermistor?
Or what else should I use to "delay" the HT voltage?

Currently I am using a manual switch, which is good for standby mode, but I'd prefer to have something, that doesn't rely on the human factor.

Edit:
In the past this was solved by using tube rectifiers, so they would need time to heat up too, but I want to use solid-state rectification, so that is not an option.


texts: Does state of charge of a (wet cell) battery influence charging rate with constant voltage?

texts: It seems to me that the current of the charging circuit would gradually decrease as the battery reaches full charge. My initial observations done by plugging an ammeter into a charging circuit seem to support this. Is this generally correct? Is this how an automatic trickle charger "knows" to stop charging a wet cell battery? Or does it instead go by the voltage of the charging circuit?


texts: Why do single op-amp DIP packages have 8 pins, rather than 6?

texts:
Single op-amps often come in 8-pin DIP packages, with 5 of those pins being standardized (or maybe it's just de-facto) like in the ones below.

Older op-amps such as the LM741 (first image) have a very bad sense of what is 0 volts, so they require offset null pins to manually adjust them.  Some newer op-amps such as the TL071 are much more accurate, but still make use of extra pins by having this feature, while their dual and quad siblings do not have this feature.  Some modern single op-amps have three unused pins, and forego the offset null completely.

So why don't many modern single op-amps come in 6-pin DIP packages?  They would still conform to the standardized layout, and fit in 8-pin DIP sockets.  But they would take up less space in circuits designed for them.

edit: For examples such as TL071, I can that they would put the offset null on it despite it's absence in it's dual and quad siblings so that there's an option for those that do want to adjust it.  But even then, many of these are available in different packages, so why not 6-DIP? That still doesn't explain it for the single op-amps that don't have offset null.


texts: A question about impedance on a multiplexer

texts:
I have designed this audio multiplexer

This is a 4 input TRRS audio switcher. Remember TRRS (4 pins: mic, left, right and ground).

I press a button and I change the input that I want to send to the output.

This switch is supposedly to work as a "universal" switch for all kinds of inputs and outputs.

Unless I connect the output of this circuit to a pre-amp, the output will always be a headphone.

But this is my problem:

Apple earbuds are 23 ohms, Audio-Technica ATH-M50 is 38 ohms, Sony MDR7506 studio headphone is 63 ohms and more pro headphones have higher impedances.

How do I deal with this?

Suppose this switcher were created with a rotary mechanical switch. Then, the input that I select would be directed to the output. So the impedance of the device at the input of my circuit would be "passed" to the output. End of story.

But this is digital. Is the behavior the same? Should I do something or let this the way I have designed and simply add a pre-amp before the output to amplify any signal that is too low?


texts: frequency divider for two output frequencies

texts:
I want to make a frequency divider from flip flops that can generate two frequencies. For example, if the input frequency is fin then the output frequencies will be fin/30 or fin/35 depending on the select bit.
Do you think that it is possible?


texts: Op Amp different supply voltage than signal voltage

texts:
I need to setup a differential op amp.  The question I have is if the source signals (from the sensor) can have a differnt power supply than that powering the op-amp.  The op amp will be sent to a microcontroller that will have different power requirements then the sensory.  Let me know if you need more follow up info.

Thanks as always!


texts: Thevenin resistance of a circuit, parallel or series?

texts:
simulate this circuit – Schematic created using CircuitLab

If I want the thevenin resistance of this circuit, do I add in series or parallel? Can't you do both? However, they yield different answers.


texts: PWM complementary square output waveforms

texts: PWM channels in certain microcontrollers such as the SAM3X8E have two complementary square output waveforms, PWMH and PWML, per channel. What is the purpose of having two waves that are the inverses of each other?


texts: What type is this fan motor and how best can I control its speed?

texts: This is from an old Westinghouse fan and I am not clear on this motor type and how to best control its speed.


texts: Detect if object is lying on the surface or is it lifted into the air?

texts:
Suppose we have a small box with a circutry and a set of sensors in it. Box is lying on the table, but it is light enough to be lifted into the air.

What I want to achieve is to switch off the circutry in a box if anybody lifts the box, and switch it on back when box is returned to the table.

Is it possible to detect if object is lying on the surface or is it lifted into the air with just accelerometer(s) and/or gyroscope(s)?
If not, what set of sensors can reliably do such a job? Proximity sensors? Distance sensors?

Thank you in advance.


texts:
I have a circuit that was originally intended for 12 volts. I am new to electronics and would like to know the best way to modify the components to work with a 9v battery. I know it can work because the LM386 chip has a wide range of possible input voltage. The site is here and the circuit below:Site.

[EDIT] I understand the datasheet but was wondering if changing any components would increase final mW output?


texts: How does this PNP transistor circuit work?

texts: How does this circuit work step by step and how do I get the LEDs to flash alternatively? (PNP transistors) (at what voltages do the LEDs turn on?)


texts: Would pictured circuit be good enough to power ATmega162?

texts:
I've read the datasheet and the application notes elated to AVR Hardware Design Considerations and EMI. From them and various Internet sources I came up with pictured design for power supply circuit for ATmega162. AVR would be connected after C3. Right now, I plan to run the device form its internal clock source, but later I plan to try with external 16 MHz crystal.

There are few things I'm not certain about. First, I'm I overdoing it with 4 capacitors near the microcontroller? Some sources say that decoupling capacitors should be placed in decades while some say that the 100nF is enough. I was thinking about using multilayer capacitors for 100 nF and 10 nF and ceramic disk for 1 nF. Would that work?

Next point is the inductor. In one document, it is placed between the electrolytic capacitor and in the other document between last capacitor and power supply. Which location would be better? I'm thinking about placing it after last capacitor close to the microcontroller, but the HDC document made me uncertain about that. As far as I understand it, coils do their best to keep current constant, so the coil should prevent spreading of pulses as the controller switches states.

AVR Hardware Design Considerations recommend tantalum electrolytic capacitor. Is there any special reason for that?

On the board, I'd place a MAX232, couple of 20 mA LEDs and 2*16 character LCD screen. What decoupling capacitor should I use near the power connector of the board?


texts: Decoupling capacitors necessary on bench power supply input on PCB?

texts:
I'm planning to power my PCB directly from a 5V and 12V bench power supply. The 5V rail will power 10+ ICs (various AND/OR logic gates, high speed comparators, and a uC). I'm estimating a max of a few hundred mAs of current draw to power everything on this rail. The 12V rail is solely for the drive high power supply of a MOSFET driver IC.
I have adequate decoupling capacitors as close as possible to each IC according to their datasheets, but given the main power is coming directly from a bench power supply, will I need any decoupling capacitors close to the power input connector?
I know when working with LDOs/switching regulators, it's necessary to have a combination of bulk capacitors and ceramic capacitors to decrease impedance over a wide frequency range and reduce output voltage ripple. Intuitively, I'd think it's necessary in my case as well since the power from the supply will travel through extra connectors/pins, which adds inductance. So far, I have a 22uF bulk cap and 47nF ceramic on the 5V rail as insurance. I'd love some guidance on how I can better design this in the future. Thanks!


texts:
A design I am working on requires a ±20v differential line driver, but I can't seem to find such a component. The highest voltage line drivers seem to be RS-485, which aren't high enough.  Fully differential op-amps seem to top out at about ±18v.

Do high voltage differential line drivers or op-amps exist?

If not, what's the best way to make one from discrete components?

Added:

The bandwidth is pretty low, a rise time of several tens of micro seconds is fine.  The ±20v output voltage swing implies 40v between the output pins.

Transmission line length is just a few inches.

The impedance is unknown, but I'm going to assume it's reasonably high impedance and low capacitance.


texts:
Having read this excellent answer on FPGA's vs Microcontrollers I have a few queries.

I recently completed a project that utilised reflectance sensors. Simply put, it reads the reflectance by measuring the discharge time across a capacitor. However, if I wanted to utilise an FPGA for this project, how would one go about interfacing such a sensor with an FPGA? I've written VHDL before with ModelSim, and synthesised using Xilinx, so I have a basic grasp of how VHDL works.

In general, are FPGAs and microcontrollers interchangeable? What is the best way to interface external sensors, such as the ones above which are digital, with an FPGA?


texts: Using Energia, how do I get around disableWatchDog() locking up my program?

texts:
Below is a short code chunk.  The code locks up on the 'Serial.Begin(9600);' line.  Can anybody tell me why?  Also, can you tell me how to get around it?

void setup()
{
  disableWatchDog();
  Wire.setModule(0);
  Serial.begin(9600);
  while(Serial.available());
}


texts:
Okay so I'm looking at RF designs and I've come across a couple of designs which need 2p2 caps.

I've seen

C1.C2/C1+C2

being plugged into a function (the tank part of the circuit) which gives a lower capacitance for the circuit i.e. C1 && C2 == 27pf (gives 13.5pf if tap taken between C1 and C2)

My question is this:

Lets say I have    + 10pf ->|-> 10pf -> 10pf

Where | is the tap does that mean I can somehow get a lower capacitance by tapping in a series of caps? (please show me the equation if poss :))


texts: reason(s) to use a 10-bit ADC instead of a 12-bit ADC?

texts: I think this question almost answers itself, but I've learned that's not always the case.  It appears from my somewhat brief googling and catalog-trawling that Microchip sells the 3008 and 3208 ADCs.  Other than the resolution itself, are there any meaningful differences in these two parts?  The price difference is $1 (in quantity) so I realize that if you're building something (or hundreds of them, really) where you only NEED 10-bits it might be worth saving a buck, but for general purpose / hobbyist type applications is there any reason NOT to just go with the 12-bit version?  I assume that the interfacing code is all the same across these?


texts: LED light bulbs in low atmospheric pressure

texts: I have these (https://www.amazon.co.uk/gp/product/B01DBOKZVK/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1) LED lightbulbs. Can I use them in a pressure of ~30kPa (21" Hg vacuum)?


texts: Technique to drive seven segment displays with external components

texts:
I'd like to ask for some advice on the circuit described below:

I'm building a matrix of multiplexed seven segment displays, with common anode. The ports D1-D3 and segments A-DP will be driven by I/O pins from an LPC1114 ARM microcontroller.

As I understand the datasheet specs for this part I cannot exceed 4mA of source or sink current in the standard purpose I/Os. See this question for more clearance on this.

The display datasheet says that the forward voltage of each segment of the display is about 2.10V. They will be feed with 3.3V. I want use 10mA of current in each segment (I believe it will give a nice brightness with this current).

With all this in mind, and for what I understand of electronics, I aks these questions:

1 - I cannot connect the segments A-DP directly to I/O ports since it will exceed the sink capabilities of the I/O. Is this correct?

2 - Almost all schematics I found on the web on multiplexed displays do that. I did not found anyone that deals with this problem. What suggestions do you have to make it possible to sink more current in each display segment?

3 - I thought that maybe I could sink segments A-DP to ground using a MOSFET controlled by I/Os. Is this a good idea? What do you think? Any schematics on this?

Thanks


texts: Does this product page contradict the corresponding datasheet?

texts:
I'm currently using N-channel MOSFET's my hobby circuit, and have had two go out on me. As a result, I'm studying them a little more and making sure I'm not doing anything that might harm them.

On this product page, the description of the item says

"The threshhold voltage is also very low, less than 2.5V so you can control it directly from a microcontroller running on 2.8V, 3.3V or 5V logic."

However, on the datasheet, V_gs(th) is listed as 1.35V min, 2.35V max.

Am I interpreting the data sheet correctly? If not, what exactly does this rating represent?


texts: Good PCB Design - Single Power Plane with 2 Power supplies (+ve & -ve)

texts:
Recently I've taken over a project which requires low noise but the design given to myself does not meet the requirements. I noticed on the PCB design It has a single Power Plane with 2 separate voltages (+5v & -5V).

Should I seperate these power sections into 2 separate planes to reduce potential for noise between the 2 voltage section in the single plane?

From my research it seems bad for noise to have a ground plane to have 2 separate sections (Analogue & Digital GND) as there can be voltage difference between the sections. People recommend connecting these sections together to reduce these noise issues. Obviously in this circumstance you can't connect these 2 sections, so that's why I thought separate planes might help.

Any and all help will be greatly appreciated. Thank you in advance!


texts: Question about RC square wave converters

texts:
I was trying to make a square wave to triangle or sine wave converter circuit, and it seemed to work, the problem is that I think there's a problem when you want to use it for something that requires a negative and positive input, like a motor or transformer.  This is the circuit that I made:

The output seems to work for a piezo buzzer but not for a motor or transformer.  It's possible there's some issue with my square wave generator, but it seems to work fine and I think the issue is that I'm not sure where I would connect a second wire as ground.  Can this be done, or would you need another converter circuit to act as ground?


texts: changing 6v lead blocks by 3,2v LiFePo4 cells

texts:
I need to replace a lead battery system with a LiFePO4 element system. the existing system is 48V 240Amp and consists of 8 Trojan T145 6V Batteries with 240Amp in the C20, the idea is to replace this system with a system of LiFePO4 elements in the case 15 elements of 3.2V.

How is the storage for a battery system calculated so that the systems have the same storage?


texts: IR2110 Mosfet Driver - Separate VSS and COM (power-logic ground)

texts:
I want to design a low budged class D amplifier based on the IRAUDAMP1 and I have a quick question.

Will there be a problem if my Logic ground and Power ground pins from IR2110 are sparate (never meet)?

Here is the schematic (well the basic of it, it still lacks some capacitors).
The "High in" and "low in" signals are provided by an op-amp whose supply pins are connected to +5V and -5V (the signal swings from +5V to -5V). The power supply providing +5V and -5V is obtained using some zenner diodes from +30V and -30V rails.

Later edit:

I should have read the Datasheet better :

"All voltage parameters
are absolute voltages referenced to COM" "VSS Logic supply offset voltage (min) VCC - 25 (max) VCC + 0.3"


texts:
What kind of gps battery can I use for uBlox NEO-M8N GPS module?  Would you please recommend gps battery? and Which can I use 5.5mAh or 11mAh?For example;

MS621FE-FL11E - BATTERY LITTIUM 3V 5.5MAH (https://ozdisan.com/bataryalar/sarj-edilebilir-piller/lityum-piller/MS621FE-FL11E)
Seiko MS920SE-FL27E Lithium ion Şarjlı Pil / 3.0V 11 Mah (https://birikimpilleri.net/endustriyel-piller/lithium-ion-buton/920/prd-seiko-ms920se-fl27e-lithium-pil)

If you know better please recommend to me..thanks


texts:
Good day everyone, may god save us from this pandemic.
I have below schematic, all of them share the same source and ground.
When 5V applied for a few seconds (e.g a button press) to the MOSFET, relay will be triggered and capacitor charged. Capacitor will keep the MOSFET on until the supply depleted and MOSFET off.
The problem arise as follow:

I applied 5V (for a few seconds) to the first MOSFET (choose any MOSFET, e.g. MS1), naturally the MOSFET turn on until capacitor charge depleted.

Once MOSFET MS1 turn off, I applied 5V (for a few seconds) to the second MOSFET (choose any MOSFET, e.g. MS2), naturally the MOSFET turn on until capacitor charge depleted. But the previous MOSFET (MS1) turn on too.

I try to the next MOSFET, the problem keep repeating, and often 2 MOSFET (MS1 & MS2) triggered when I applied 5V to current MOSFET.

The problem not repeating if I wait all MOSFET turn off and add more waiting time for 1 minute or more (waiting all capacitor fully empty).

Attachments:

Schematics
Schematics Simplified
PCB Layout

My questions are:

What happen to my MOSFET? Do I need to replace them?
How do I prevent previous MOSFET turn on, when other MOSFET triggered once its turn off?

Thank you


texts:
We have designed a custom prototype board based on the Arduino Mega (ATmega2560).
Our knowledge on electronics are limited so we assigned someone else to design the board.

On his design he used the following circuit for noise filtering and decoupling the Voltage on the AVCC and AREF pins of the 2560:

My problem is that on the Arduino Mega R3 reference design the decoupling is done this way:

So there is a difference that on the AVCC there is no coil filtering (L4) and that they are using 3 100nF decoupling capacitors, while hs is using 1 100nF and 1 10nF
Also on the AREF decoupling is done with 1 100nF on the Reference design, while he is using 100nF and 1nF

When asked he said that his approach is better, but since my knowledge is limited on the field, I wanted to make sure we are definitely doing this correctly.

Here is the Reset circuit


texts: Do I have to equate clock and Data Bus propagation delay for Transmission Lines?

texts:
My question is about SDRAM timings for clock and DataBUS. Som designer advice that clock pin has to be the shortest one. Data Bus may be longer than these because of the some problems. But clock trace is important. When I looked at Propagation delay for transmission lines it says:

v = (3x(10^8)) / SQRT(Er)

and multiply x (length of transmission line) the exact time of the signal delay i think. (by formula)

So that confused me. if my clock signal 2 or 3 inches shorter than dataBUS from the formula it seems they wont be matched. I think some kind of signal on the receiver side will be like that :

Clk : __n

Data: ___n

Do you agree with me? How I can handle this problem (I am not sure if it is a problem)


texts:
Hi guys I am trying to implement galvanic isolation for my lm555 square wave generator. I am designing a marx generator so this is essential.
I am new with transformers, at the moment all I want to get is the same square wave at the secondary side of the transformer but LTSpice doesn't even want to run it. Can anyone give me some advice? Am I missing any components? Cheers. Here is the circuit i am trying.
The square wave is at around 8kHz

This is the output across the resistor after grounding the secondary side.


texts: Interpreting the state of the transistor

texts:
In this scenario, let's say that XMM2 has a reading of 0 A and XMM3, being a voltmeter, has a reading of ten volts.
I presume that XMM2 reads the base current, so since there is no IB, there will also be no IC by the relation: $$I_{C}=\beta I_{B}$$ It is an npn transistor, so it is going to amplify. Depending on the supply voltage VBE, the transistor is going to work in three states: active, cutoff, and saturation.
If VBE is less than 0.7, then the base-emitter is not configured properly, which can then be seen probably via the input characteristics. Hence, the depletion region is not going to reduce as the electrons hardly move to the base. In other words, no current is flowing. Thus, since IC does not collect any electron from the base current, IC is 0.
And since VCC, VCE, and Vout are at max (10 volts) and IC = 0, the state of the transistor is at cuttoff. It almost looks like an open circuit; no emitter current, and the base voltage must be less than both the emitter and collector voltages.
Is my interpretation correct?


texts:
Like basic C language I tried making a define as follows

#define RED PA0
#define ON 1
#define OFF 0

void main(void){

    DDRA = 0xFF;

    while(1)
    {

        RED = ON;
    }
}

I get an error which I havn't seen before:

  lvalue required as left operand of assignment

What does this mean?


texts: Why does capacitance not depend on the material of the plates?

texts:
As a student, learning about a capacitor after understanding what a resistor is, it was quite surprising to note that the capacitance does not depend on the nature of the plates used, at least in any type of capacitor I have known.

I am guided, "it makes no difference as long as the plates are conducting." Is that true?


texts: What does this symbol mean? And I have some basic problems which the book didn't mention

texts:
A power system book asked me  this question, but honestly I don't understand the circuit  of question and the solution which author provided.

Question:

There are 3 primary currents, \$I_R,I_S\$,and \$I_T\$ with \$40\sqrt{3}A\$, of the three phase transformer, and the current ratio of the currentvtransformer (CT)is \$200/5\$.  What is the current value of ammeter \$A\$?

The solution:

current value of Ammeter \$A =|\vec I_T-\vec I_R|=\sqrt{3}\vec I_R=\sqrt{3} \times 40\sqrt{3} \times \frac{5}{200}=3A\$

Sorry, I am not working on the power transmission and transformer, so I will have some basic problems, which the book did't mention.

What does the symbol, which I circled in red, mean?
Why does current value of ammeter \$A =|\vec I_T-\vec I_R|\$, not \$A =|\vec I_T+\vec I_R|\$, or \$A =|\vec I_T+\vec I_R+\vec I_S|\$
Does \$I_R,I_S\$,and \$I_T\$ have some specific meaning, or I can just replace them with \$I_1, I_2\$, and \$I_3\$?
Why does \$|\vec I_T-\vec I_R|=\sqrt{3}\vec I_R?\$


texts: What is the difference between worst hold slack and worst negative slack

texts: I have been looking all over google and I can't find a clear answer for what is the difference between worst hold slack and worst negative slack in the timing summary in vivado.  Right now I am building a integer divider and I am passing the worst negative slack but failing the worst hold slack.  What is the difference between the two?


texts:
Is there any reason not to load the Arduino Pro 8Mhz bootloader onto a 5V arduino (custom design, just a standard ATMega328p)? I'm doing some battery backup stuff with it that doesn't play nice with 16MHz (since the backup is only 3V). But I want to run the rest of the system at 5V under normal power conditions.

Should I be able to just load the Arduino Pro 3.3V 8Mhz bootloader (and select that profile, or many create my own)?

Anything to watch out for?


texts: What is the common mode in common mode input voltage range?

texts:
The common mode voltage at the input of a difference amplifier is defined as $$\dfrac{V_1+V_2}{2}$$ and common mode input voltage range is the range of voltages at the input for which the opamp works as it's supposed to.
But what is common mode about that?


texts:
I'm trying to use a HIH4030 humidity sensor, where the output value is provided to a XBee.

Considering that output sensor max output voltage is around 4V and the XBee ADC only supports 1,2V, I took some time to choose the correct resistors for a voltage divider to get a decent ratio. I end up choosing a 120 ohm and a 270 ohm resistors to get a ratio of 4V to 1V.

And in this case I wasn't getting any values on my XBee. When I measured the signal, I had about 31mV going out the voltage devider when I should have around 800mV.

Now, correct me if I'm wrong (and there's a good chance that's the case), but the reason for these low values are due to the low total resistance value (R1+R2 = 390ohm) and the low current value going out the sensor. The HIH4030 specs say that the current supply varies from 200uA to 500uA, so I'm assuming that from this sensor I won't get higher currents than 500uA. Is this a correct assumption?

Anyway, taking this assumption as the correct one, through ohms law,

V=RI. V=390*0.0005, thus V=195mV which is hardly enought.

I was considering getting higher resistance values, at least to a total of R=1,2/0.0005.

Am I proceeding correctly?


texts:
I’ve been trying to build an induction cooktop, my inspiration was this post:

https://www.instructables.com/id/Powerful-yet-simple-induction-heater/

And after some help , I’ve built a circuit according to this schematic:

And it actually worked! I mean, not the way I expected but it worked. The problem is that it’s kind of weak, I did some tests and my convencional gas oven is capable of boiling 150 mL of water in about 2 minutes. With the circuit I’ve built not even after 5 minutes the water boils, it gets hot but I can still put my finger on it for a second or so. So, my question is, do you see anything I could do to improve the efficiency of my circuit? The easiest thing I could do is to change the value of the capacitors adding or taking some of them away. I’m using a stainless steel pan, I’ve tried using an iron pan but the results were the same, if not worse. You’ll also find some pictures of the actual setup below. Any more details needed I’ll try to provide you. Thanks in advance!


texts:
I want to desolder an element from a PCB, I can see all the solder joints that are holding it on to the board and I can reach all of them easily.
I am not very experienced in working with a soldering iron, tbh this is the first time I am working with one but I informed myself how to do it correctly and I also got myself a desoldering pump to remove the melted solder joints.

The only thing that is giving me headaches is the fact that I read it can be difficult to desolder solder joints that are close or on a ground plane because the ground plane absorbs heat.
I took a look at my board and this may be the case for 3 or 4 of them.

My question is do I have to take special care of those solder joints, do I need a specific tool to remove those or can I remove them just like the others?


texts:
Ok so here's my situation.

I have a custom board with a micro controller that has a 6 pin connector. If I plug in a device to the connector that requires power it should provide somewhere on the order of 200ma @3.7v (from my PSU) to said device. However it's possible (and expected) that the same connector might be used with another device that is sending power @5v and in that case I want to close the circuit and not have any flow in or out.

1) 3.7v -----> Out (To device requiring power)

2) 3.7v ----> X <---- 5Volt (powered device attached shut it all down)

What's the best circuit/solution for this? Some type of diode switch?


texts: Split any headphone with remote control and mic into Mic TRS+ Headphone TRS+USB

texts:
The main question is in the title.

So I bought a headphone mic Y splitter yeasterday, and the right headphone output didn't work. I took it apart and tried to solder it to the headphone jack with no success(cos my soldering skill sucks, and I'm using a butane soldering iron).

And I suddenly came up with a idea: why not utilize the remote control on the headphone to control the computer also?

I have looked around and realized different headphone remote control uses different resistance for different purposes. So how can I get the computer to know the resistance level and configure with a software on the computer to pair a resistance level with a specific action?

This is the simplified version of what I am thinking of:


texts:
I bought a cheap Ni-Mh battery charger from Aliexpress to charge my rechargeable AA and AAA 1.2V batteries but before I plug them in, I checked the voltage on the charger terminals and it is reading 5V.

I am attaching the link to the product page and also will link image containing specs of the charger below.

So, I don't think I should keep the batteries for charging right? or can it have some intelligent voltage switching technique or maybe if I put all four batteries in it will divide the voltage which it should not but I am not an expert so....
Edit: Added internal circuit images

Product link : Charger


texts: Does the voltage across an electrolytic cap significantly alter its lifespan?

texts:
I've heard two sides to this question: Does the voltage across an electrolytic capacitor significantly alter its lifespan?

Yes, it does. The rating should be 1.5x - 2.5x the expected voltage.
No, it doesn't - and United Chemi-Con say so themselves. (Search "(a) Operating Voltage")

I'm more inclined to believe UCC, but I've seen the 1.5x-2.5x rule applied on commercial high reliability designs too (even when the rails were never expected to exceed cap rating, for example an overvoltage protection circuit is used.) I've also seen the opposite in high reliability designs, for example one oscilloscope (which is still going after 19 years) seemed to use a combination of both.


texts: Differences between LM317, AMS1117 and L7805

texts:
I am trying get a 5V to power up AVR microcontroller. The power will be supplied either from 5V USB power adapter or from motorbike battery (about 11-13.7V).

I have one piece of both 7805 and LM317 voltage regulators, but I don't have any AMS1117. I would like to know the advantages and disadvantages of using any of these parts.


texts:
Here is my flyback converter design.
Vin: 110V
Vout: 24V
Iout: 1A (max)
Desired efficiency: 85%
Transformer ->
P1: 6T
S1: 6T
S2: 5T (aux)
Vro: 24V
EFD30
I determined 15uH for Lp
Ls1: 15uH and Ls2: 8uH
SMPS IC: NCP1252-A (max duty cycle: 48%)
datasheet
Mosfet: STP75NF20 datasheet

When the transformer is not connected at the circuit, PWM signal at the mosfet gate is CLEAR and PROPER.
But, the transformer is connected at the circuit, gate signal form is being broken.

I thougth that the SMPS IC could not be able to generate the gate signal when directly connected with mosfet. So, I used a mosfet driver. But, the result is the same. Frustration! So, my efficiency remains low (25%)
Why is the gate signal being broken?
I measured leakage inductance as 5uH. Does the leakage inductance cause a problem about PWM?


texts: LTspice giving incorrect voltage value for simple first order low pass RC filter

texts:
I drew this low pass filter circuit to have a output voltage of 5v across capacitor at a frequency of 100Hz sine wave of amplitude 10v.
But I am only getting 4.5 volt as output in steady state. I am doing simulation in LTspice on Ubuntu. What mistake I am making?

R = sqrt(3)/(2*pi*fC) - This is how I calculated R for a given C to have a half voltage drop across C


texts: Can a 6V rechargeable battery be charged to 5V after complete discharge?

texts:
I live in a area where there is power cut. I have to power a Raspberry Pi (a device rated as 5V and 300-700mA) through micro USB continuously. So I decided to make my own mini inverter.

Now I have a 5V-2A DC adapter and a 6V-4.5Ah rechargeable battery. The battery is discharged and can only supply 2-3V now. So can it be charged to 5V using the 5V DC adapter?

Also please take a look at the circuit I am using for my inverter. Please tell me what possible resistances should I use and at what places?


texts: Is impedance triangle considered as phasor diagram

texts:
Voltage triangle of series RL circuit considered as phasor diagram, since there is a phase difference between voltage and current in Voltage triangle.

But there is no phase difference concept in impedance triangle, still is it considered as phasor diagram ?


texts: Leftover current after current limiting resistor

texts:
This question is related to my another question here.

In crux, I would like to sink current of TLP521 via 74HC595n shift register. The TLP521 is connected with a resistance such that the current is limited to 16mA.

My question is that if the current is limited to 16mA and the TLP521 "led" consumes it, then how much is left over for the 74HC595N to sink?

I understand that if "led" was not in place (consider a short), only then the 74HC595N would see a total  16mA current and would struggle to sink it ( as it can sink only 6mA current). But in this case, the LED would "eat" (sorry but this is my analogy of current) the current any a tiny amount might be left over for 74hc595 to sink.


texts: Is this clamping voltage divider for a high-impedance input a good, robust design?

texts:
I have an AC input as follows:

Can range from ±10V to at least ±500V continuously.
Runs from roughly 1 Hz to 1 kHz.
Needs > 100 kΩ of impedance on it, otherwise its amplitude changes.
May occasionally be disconnected and subject the system to ESD events.

When the input is below 20V, I need to digitize the waveform with an ADC. When it is above 20V, I can ignore it as out of range, but my system needs to not be damaged.

Since my ADC needs a relatively stiff signal, I wanted to buffer the input for further stages (in those, I will bias it, clamp it to 0V to 5V, and feed it to an ADC).

I designed the following circuit for my initial input stage to get a safe, strong output that I can feed to further stages:

simulate this circuit – Schematic created using CircuitLab

My goals are:

Ensure > 100 kΩ of impedance on the source.
Change a ±20V input to roughly a ±1.66V output.
Provide a stiff output.
Safely handle continuous high-voltage inputs (at least ±500V).
Handle ESD events without dumping much current/voltage onto the ±7.5V rails.

Here is my rationale for my circuit design:

R1 and R2 form a voltage divider, reducing the voltage by 12X.
The TVS diode reacts quickly to protect against ESD events on the input, dumping them to my strong ground, without dumping anything onto my (weak) ±7.5V rails.
The TVS diode also handles extreme overvoltage (sustained ±500V) by shunting to ground. It is past R1 to limit current in these cases.
D1 and D2 clamp the divided voltage to ±8.5V so I don't need a high-voltage capacitor for C1; being after R1, the current through them is also limited.
C1 decouples the input signal. It will be a bipolar electrolytic. It needs to have a relatively large capacitance to allow the 1 Hz signals to pass unaffected:
$$\frac{1}{2 \pi R_2 C_1} \ll 1 \text{ Hz}$$
$$C_1 \gg \frac{1}{2 \pi \times 1 \text{ Hz}\times220 \text{ k}\Omega} = 8 \mu\text{F}$$
R3 and C2, with R3=R1, compensate for input current bias and offset in the op-amp (rather than just shorting the output to the negative input); also form a low-pass filter:
$$f_c= \frac{1}{2 \pi R_3 C_2} = 36 \text{ kHz}$$

Is this circuit optimal for my goals? Can I expect any problems with it? Are there any improvements that I should make, or is there a better way to accomplish my goals?

EDIT 1

I'd originally said this needed to handle ±200V continuously, but I think ±500V is a safer target.
In order for the TVS diode to work as is, R1 needs to be split into two resistors, here R1a and R1b, as suggested by @jp314:

simulate this circuit

EDIT 2

Here is a revised circuit that incorporates the suggestions received so far:

Zeners across the power supply (@Autistic).
Resistors leading into them (@Spehro Pefhany).
Fast BAV199 diodes (@Master; a lower-leakage alternative to the BAV99 that @Spehro Pefhany suggested, albeit with a maximum capacitance of around 2 pF rather than 1.15 pF).
TVS diode out front and upgraded to 500 V (@Master), so it handles only ESD events, protecting R1.
Dead short from op-amp output to negative input (@Spehro Pefhany and @Master).
Decreased C1 to 10μF (@Spehro Pefhany); this introduces a 0.3% voltage drop at 1 Hz which isn't as good as original the 220μF cap, but will make sourcing the capacitor easier.
Added 1 kΩ resistor R6 to limit the current into OA1 (@Autistic and @Master).

simulate this circuit


texts: Why can't RC circuits oscillate in frequencies higher than RLC or LC circuits?

texts:
The resonant frequency of a tank circuit should be decreasing either with capacitance or inductance increasing according to the equiation given below.

It should be because, it will take longer time to charge a larger capacitance to unit amount of charge or start unit current against the "inertia" of a longer wire/inductor.

In a sense, a RC circuit also could be considered as a RLC circuit with negligible inductance (a much shorter lenght of wire than an inductor).

This makes me wonder why is it not possible to use only smaller capacitors and a short wire (so that their capacitive and inductive reactances match) to produce frequencies even higher than a LC or RLC circuit which has a larger indutance than RC?

What is the obstacle that practically limits building high frequency, low capacitance RC circuits?


texts: Slowing down blinking rate on an LED with built in IC

texts: I have a Kingbright, L-796BSRC-B SUPER BRIGHT RED blinking LED with built in IC. Having just installed a new home wireless alarm system which has a battery powered external sounder, I wanted to connect the existing 12v supply of the old, redundant wired in box to this LED to run as a permanent indicator. I did and it's working fine but blinking rather too quickly. Can I simply slow down the blinking rate from obviously outside the IC?


texts:
Long story short, I have a Toshiba laptop. Its adapter outputs 19.05 volt and 3A.
I wanted to build a powerbank for my laptop. I have built one using Li-ion cells. 5 cells in series with each cell as 3.7 volts and it works just fine but the cells take a lot of space and still have a capacity just around 6000 mAh...
So I was thinking of using mobile powerbanks with capacity as high as 15000 mAh are easily available and I have also found a DC boost converter that can boost from 5V upto 45V.
Do you think if I connect the powerbank's 5V port to the boost converter and set it to 19.1V. Will it be able to run the laptop?


texts:
I'm putting a Raspberry pi zero on a model train. The train tracks supply 12V DC which I step down to 5v with a Pi Jack. However, because the power is being supplied via the tracks, I can't be certain of the polarity of the DC power.

How can I invert DC polarity if it's reversed from what I expect?


texts: What's the best MOSFET for switching small currents?

texts:
What are the most important characteristics to look for in a MOSFET for switch a precision 50nA load?

The MOSFET should be able to switch the load on or off within 1us.
The overshoot/undershoot while switching should be minimised.

Edit:

Here's a simplified schematic of the circuit I'm describing.

The load is at 3.3V and the 66M Ohm resistor gives very close to 50nA current when M1 is switched on.  This is affected by the Rds_on of the MOSFET but with a 66M Ohm load resistor it's going to be negligible for pretty much any reasonable Rds_on.

Overshoot/undershoot is fine as long as the voltage at the load (non-grounded terminal of R1) does not go above 3.3V or below 0V.

Here's an example simulation:

The transistor is a BSS84, the En pin is fed the following waveform:

The rise/fall time of this signal is 10ns.

Here is the current through R1:

The turn-on response is quite fast, the rise time from 0nA to 50nA is 14ns.  There is some undershoot of 3.7nA.
The turn-off response is terrible, the fall time is 18ms from 50nA to 50pA.  There is also 6nA of overshoot.

During turn-off, the current/voltage drops very quickly until the load voltage is 2.1V then it decreases slowly like a capacitor is discharging.

I want the load current to drop to 0A within 1us ideally.  I presume this could be accomplished by finding some way to drain the drain-source capacitance of M1 quickly once M1 has been shut off.  I tried using another MOSFET as per the circuit below but it didn't achieve what I wanted.

Edit 2:

I replaced the P-channel M2 with an N-channel and it seems to work well:

The current through R1:

I chose an M2 with very low Rds_on.  The current through R1 now drops to ~0A in 12.5ns.

Why was everyone saying this would be so difficult?  Am i missing anything here?


texts: Why does voltage split when an additional resistor is added?

texts: When you have one resistor in a series circuit, the amount of voltage taken up by that resistor is 100%. Adding another resistor (same Ohms) makes that voltage drop 50%. Why, since only current should be changing, and the voltage (joule per coulomb) shouldn’t depend on current (coulombs per second)? It’s like the voltage knows that there’s another resistor (before it hits the first one) and decides to split its energy for each. But obviously that isn’t the case because voltage isn’t a sentient being, so what causes it to split its energy rather than imparting all of the energy on the first resistor as it normally would if there wasn’t another? At first I thought the answer was that the current decreases as a result of the resistors and that’s what causes the voltage to decrease for each, but that doesn’t make sense since the amount of electrons shouldn’t control the energy they carry.


texts: 5V source directly or 12V stepped down to 5V

texts:
I'm setting up a circuit to handle a 5V LED strip, which consumes between 500mA and 1A in bursts. The power source is a serial ATA cable which has 5V and 12V lines from the PSU. Without a capacitor and just using the 5V directly I see voltage drop down to 4.6V. With a 1000uF cap in the parallel, the drops look less dramatic / smoother and will stop at maybe 4.7V (just watching my meter without any real logging to observe). This is like 20 LED's on a WS2812B strip.
Pondering how to limit the drop so ideally there isn't one at all.
I'm thinking about taking the 12V line, using a step converter - believe the one I have is LM2596 based (It handles up to 3A and in past testing with a steady 1A, it gets slightly warm but not hot) - and use the 5V output from that to power the LED's instead. I'm not sure how this converters segment handles surges in current. If there is a surge will it smooth out the spike better?
Also, with regards to the capacitor(s). If I were to go the 12V route, not sure if I should wire one (or multiple parallel) caps in the circuit, before the step down? or after it's converted? I was using a 470 uF and then a 1000 uF cap, and now I'm wondering if I should try multiple caps (1000 is the largest I have on hand) to address my concern, instead of veering off into the 12V versus 5V question?


texts: Why the address of 8085 interrupt are 8 locations apart and not in continuation

texts: If it's for Interrupt Service Routine (ISR) in which microprocessor pushes the content of program Counter(PC) to stack and then loads the Vector address in PC and starts executing the ISR stored in this vector address then what if the ISR needs more address locations. Will it overwrite the next interrupt's vector address? In fact for RST 4, TRAP(RST 4.5), RST 5, RST 5.5, RST6, RST 6.5, RST 7, RST 7.5 chain there's only 4 locations for ISR.


texts: Assign signs with passive sign convention in transient analysis

texts: It's known that most books prefer the usage of passive sign convention and recommends to set polarities to all schematic elements before writing KVL equations. But how to proper set signs in schematic that is used for transient analysis like below? One polarity is set and one current direction is set ("i"). The second was selected by me? But what about signs on nodes of elements. In this situation I must properly identify which capacitor is a consumer (C1 - I think) and which is a power source (I think it's C2). What about initial voltage on capacitors, how the schematic would be if I add two voltage sources that represents initial voltages on capacitors and how to properly setup the polarities on them? It's all I need to write the proper KVL differential equation to solve the transient response. Any suggestions, please?


texts: Inductor's self-resonant frequency: Do we want it to be high or low?

texts:
Inductor selection always confuses me. There is a spec for inductors as self-resonant frequency. For example, on digikey, as SR frequency of inductors increase, the price may increase or decrease. But why? See this graph below, behavior of self resonant frequency response of the inductor:

Assume we have a circuit board with SMPS has switching range in between 1-2 MHz and a few other analog blocks work in up to 4 MHz. In this case, is it smart to use an inductor with SR frequency below 1 MHz or over 4 MHz? And why?


texts:
I'm a long time reader of this site but my first time as a poster.

In my scenario I am using a 6V AAA powerbank and want to have a simple indicator to tell me if the batteries are nearly flat say at a 5V level.

I'm looking to make a circuit that when I press a switch a bi-colour led lights up green if the voltage is above the set level, say 5V and red if it is below that value.

I found this post that was close to what I am trying to achieve, but I couldn't quite work out how to arrange the transistors for a bi-colour led.

Would someone be able to provide me some advice?


texts: What to use in finding frequency response : \$G(s) \cdot H(s) \$ or \$ \dfrac{G(s)}{1 + G(s) \cdot H(s)}\$?

texts:
While studying frequency response of control systems, all of the sources I'm referring to is considering unity feedback system i. e. H(s) = 1 & drawing Bode plots and polar plots on basis of that.

But what if feedback is not unity? Do I have to do analysis and Bode plot with

\$G(s) \cdot H(s)\$ or \$ \dfrac{G(s)}{1+G(s)\cdot H(s)} \$ ?

and why?

Note : G(s) is forward path transfer function.

I thought it should be

$$\dfrac{G(s)}{1+G(s)\cdot H(s)}$$
but one not-so-reliable source (tutorials point website) states that it has to be

$$G(s) \cdot H(s)$$

Also why \$G(s) \cdot H(s)\$ is called open loop transfer function?


texts: I'm starting learn AVR microcontrollers. But my OS is Linux. I have installed avr-binutils with avr-as. But I can't find documentation on it; especially, avr syntax (for example, for x86 standrd intel and as syntax differ).


texts:
I am a beginner in electronics. For a project I have to use five 4017 counter and I understood how they works: one of ten outputs is high at the same time.
But at some time, I need to set HIGH the 10 outputs of the five counters simultaneously. In your opinion, what is the best way to achieve that ?

I thought about using OR gates with one input set to HIGH after the counters but I can't find IC with more than 4 gates (CD4072B for example) so there will be a lot of OR gates on the circuit. Also, I thought about using diodes, is this a good idea or is there IC which can achieve what I want ?


texts: Instrumentation amp vs buffered difference amp

texts:
The topology often used within integrated inamp packages often look like this (where the gain is conveniently set by a single resistor):

There is another topology that looks more like a buffered difference amplifier which doesn't seem to be used that often in integrated packages because of difficulty in user selectable gain:

The top topology results in a diamond shaped output voltage vs common mode input voltage plot as described in  Analog Devices AN1401, where the sloped sections are due to the gain being handled at the first stage of the amplifier. Even if the opamps used are RRIO this diamond shape exists:

Would the second topologies (buffered diff amp) output voltage vs common mode input voltage show a more rectangular shape with greater area, thereby giving better common mode voltage performance?


texts: Super capacitors high current charging and discharging

texts:
simulate this circuit – Schematic created using CircuitLab

simulate this circuit

I've been playing around with the idea of using super capacitors as the main way to start my car (basically the car is a pain to start at times due to the way the engine is setup and being stuck without a way to start the thing at times is a real pain). I've seen Maxwell sell super capacitor bank for trucks which you hook up to the starter motor and alternator to allow the truck to be shut off and run ancillaries whilst still being able to start the truck when you need as the batteries are isolated from the super capacitor starting bank. Could buy one of these but they are extremely expensive/overkill and I'm happy to have a play to make my own.

Attached is a rough circuit diagram from what I've found so far. May be wrong but its a start/what I could find from researching various things online.
Some Notes on it:

There are two power sources; Alternator output and a low power solar panel. The alternator is meant to be the main source of power/charge with the solar panel there only to top up the capacitors due to the leakage current
Leakage current needs to be low, so any balancing after the alternator power has been removed needs to be highly efficient else I'll go to start the car and it won't work (especially if I've left it for a few days). This rules out resistive balancing.
Active balancing of capacitors is ok, but all the ones I've found only have very small balancing capability and from what I could gather, if you want to use large amounts of current >10A to charge it fast, they just can't keep up and you can get voltage imbalances leading to damaged capacitors/explosions.
Capacitors used will be 3kF or 3.4kF, probably Maxwell branded as I can get a hold of these with a max rated voltage of probably 2.85v. Max used voltage is aiming to be around 2.5v.
Max voltage out of the alternator should be around 15v
Max voltage out of the solar panel is around 19v, but typically a lot lower than that
Buck/Boost converter used to try and keep the capacitors as close as possible to 15v. This is only from experience when starting the car, the higher the battery voltage when starting, the better/easier it starts.
Output current of this setup when in series unit needs to be in the order of 200A at 15-11V
Option 2 is something that I'm not 100% sure on. Being able to charge in parallel at 2.5V in my head seemed like a good idea as I could have individual buck converters to charge each capacitor to maximum voltage with a lot more current that I thought I could whilst maintaining capacitor balancing from the off the shelf products, thereby charging faster. Then they would automatically work in series when the start motor is engaged.
I forgot to put this on the image but I'd need a diode on the output to make sure I'm not getting any back EMF etc from the starter motor.

Any comments on suggestions on which way to go would be appreciated. Nothing here is set in stone and I'm happy to take suggestions on any part of it. This is more of a learning exercise as much as anything else. I have some level of electrical knowledge but this is generally limited. If I've done something dumb or if I ask dumb questions go easy (I do try to research things before I ask more questions).

EDIT: finally managed to get circuit schematic maker working. Both solutions now attached as schematics.

Thanks
Tyler


texts: how much power is radiated by cell towers?

texts:
I want to know how much power is radiated by cell towers of GSM (1.8 Ghz), 3G (2.1 Ghz), 4G (2.6 Ghz) ?

I want links to references if exist.


texts: Need to extend bulb life on 13vDC, 100 watt headlights

texts: I have a boat, that uses two 13V, 100 watt lights.  The output from my alternator is running at 13.8V-14.5v and it is rated for 90 Amps. These lights run $270/pair and seem to burn out quickly. They are factory rated for only 25 hours at 13v. A technician at a bulb supply store read a chart and told me that running the bulbs at 14v reduces their lifespan by 60%. So, now these expensive bulbs only last for 10 hours.  They are intended for docking the boat only and not continuous use.  The same tech that told me I was burning the lights up so quickly told me if I reduced the voltage in that circuit, I would get a huge increase in the lifespan of those same bulbs. Therefore: I would like to reduce the voltage in the circuit to 12v and still be able to draw the 100 watts to run the lights as needed. IF the solution is impractical, I will look for other lights, but cutting a new hole in the hull of the boat (for new lights) is my last resort.


texts: As I increase the volume of this amplifier the sound gets choppy and the negative power supply regulator gets hot as hell

texts:
I have designed and built the project below.

Open the image on new window or imgur will not let you scale it up and you will not see the components.

This is a 4 channel stereo switch. You press the button and select channels 1, 2, 3 and 4 in sequence. The channel you choose is sent to the TEA2025 and amplified.

This is almost working well but I have two problems: when I increase the volume beyond a certain point the audio starts to fail, like it is being interrupted and when that happens the LM337 from the power supply starts to heat fast.

The input comes from 12 VDC external adapter. This power supply creates a virtual ground (-6 VDC, 0 , +6 VDC). The LM337 is responsible for the negative voltage.

I have asked this on reddit and someone there answered this:

  Strangely enough, the LM337 actually provides the positive voltage. As
  the load between the +6v rail and virtual earth increases, the virtual
  earth will try to move towards the +rail. Only current through the
  LM337 can drag it back again. A fairly simple fix is to add a power
  resistor from earth to -ive rail. Enough, say, to balance out the
  current drawn by the output IC at half power. That will mean that the
  317 will get a little hotter on low volume and the 337 will get a
  little cooler on full volume.

I am not sure if I know how to calculate this resistor and btw is there a way to make a symmetrical power supply from an external 12VDC adapter input without this problem or making this virtual ground ground be at 0V always?


texts: LiFePo4 cell risk of explosion during cool down

texts:
A 3 Ah LFP cell is charged to 100% at 25°C temperature.
What happenes if I cool down the charged cell to -20 °C temperature?
At -20 °C the cell can store only 2 Ah.
Does it mean, the cell is overcharged by 1 Ah, equivalent to 30 %?
Is there a risk that the cell will explode?

I assume, that this cell would be protected by the BMS in a battery configuration, if the overcharge causes an overvoltage.
In this case, the BMS should dissipate the 1 Ah overcharge in order to not exceed the max cell voltage.


texts:
What options exist for limiting current in this scenario?
I have been searching for an option and it looks like I need to reduce the field on the alternator but I don't understand enough to know if that will work on its own with a DC/DC charger.
At the moment the option seems to be to buy a DC/DC charger that does the number of amps I require (being 0.5C of the LiFePO4))

simulate this circuit – Schematic created using CircuitLab
EDIT: Added information per question/comment
The charger is a CTEK Smartpass120S coupled with a CTEK250SE.  The 120S does up to 120Amps in a "passthrough mode".  And the 250SE does 20Amps as a proper DC/DC charger and has selectable profiles.
When the battery can take a current of over ~25amps both the 120S and the 250SE are engaged and "doing their respective things".  Once the 120S detects that its current is below ~6amps it disengages and then the 250SE continues and applies a proper charging profile.
https://www.ctek.com/au/all-products/leisure-sport/d250se
https://www.ctek.com/uk/products/leisure-sport/smartpass-120s
NB: Interestingly there is no actual digital connection/signalling between the two units.  They work in tandem or stand-alone and are designed to work as a pair for up to 140Amps
I don't currently have a LiFePO4 battery connected, I am still using AGM, the most current I have seen my AGM suck up is 75amps, and it's allowed as much as it wants.  However, I am migrating to LiFePO4 Cells and I know that they will take all 140AH if they can.  So looking for a way to limit that so I have my charging system sorted.


texts: Capacitor sizing on a voltage regulator output

texts:
I have an application in which an RFID reader demands 200 mA of current when it attempts to read an RFID tag. For some reason the current switcher power supply either can't supply enough current or can't supply a clean enough voltage and I end up with a poor performance on the reader.

I want to use a standard LM7805CT regulator in place of the switcher, but how large of a capacitor should I use? The datasheet suggests 0.1 uF, but I'm not sure that is large enough since the reader gets turned on and off a lot.

I am regulating down from a 24 V battery (it is pushing the limit of that particular regulator, but I will add active heatskinking to it).


texts:
I am a keen fisherman and always looking for new projects to work on in my spare time.

My latest pet project is that I'm looking to increase the capacity of the batteries that power my 3W cree LED headlamp, by making a battery pack that clips to my belt.

The lamp currently runs off 3 x AAA 950mAh batteries, it has quite a long burn time but after the first hour there is a significant decrease in brightness, which continues to decrease throughout the night.

I have 8 Eneloop AA 2000mAh batteries lying around the house, and my first idea was to use 6 of these batteries by running two sets of 3 AA batteries in series and parallel giving me 4.5V and 4000mAh. But I was thinking I could also use the other spare 2 batteries.

My question is would there be any real benefit is using two sets of 4 AA batteries in series and parallel giving me 6V 4000mAh then reducing the voltage down to 4.5V using a regulator or am I just wasting 2 batteries doing this?

Any help appreciated. I also appreciate that it would probably be simpler just to buy a new lamp. But where's the fun in that?


texts: Would it be a good idea to use a TRIAC as a crowbar in this application?

texts:
The idea here is to sense when the electrodes of the transformers secondary make contact which would be sensed by the optocoupler and trigger the SCRs to switch ON the transformer for spot welding. This circuit would go in series with one of the cables from the secondary.

I am correct, the TRIAC being the resistive load would get HOT and fail before a spot weld would ever happen.

Is there a better option to replace the TRIAC and short thos lines when spot welding.


texts:
It seems that a well-designed SMPS has a capacitor connecting the ground planes of the primary and secondary sides of the transformer, such as the C13 capacitor here. What is the purpose of this capacitor?

I've let myself understand that it's for EMI suppression, but what kind of EMI does it suppress, and how? It seems to me to be the only leg of an open circuit and thus completely inert, but obviously I'm wrong about that.


texts: How to toggle a pin in Harmony framework for a pic?

texts:
I'm new to pic's and the harmony framework, and i'm trying to toggle a pin from high to low and vice versa in the interrupt callback of the Timer.

I configured my oscillator to operate at 32 MHz

or at least is what appears here, so i suppose it's right:

Then i configured a Timer Driver, with prescale 256, so each tick is 8us:

Now my question, i want an interrupt to happen at each 8us, and i want to toggle a pin (RG0) at each interrupt. How can that be done?

I see what seems the interrupt code at the file system_interrupt.c:

But if inside that function i put the following line:

LATGINV = 0x00000001; nothing happens, i go check on the oscilloscope the signal and there is no toggle.

If i put the same line on main.c it works, the problems is that it doesn't seem to be accessible in system_interrupt.c


texts: Using Smart Phone displays in Raspberry Pi or other computers

texts: Many smart phones aren't used after 2-3 years but the displays are good and i was wondering why no one is using those display within electrical components? Wouldn't it be great to have a module which makes it possible to use smart phone displays as general purpose displays for any computer? Is there something like thyt?


texts: Where do I get 18650? e scooter battery pack

texts:
There is some chinese 18650
http://www.aliexpress.com/item/4pc-a-lot-Free-shippng-18650-Li-ion-Rechargeable-3-7V-9800mAh-Battery-for-Flashlight-Newest/32518061115.html?spm=2114.40010208.4.8.WalUmo

What is the catch here?

10pc a lot Free shippng 18650 Li-ion Rechargeable 3.7V 9800mAh Battery for Flashlight Newest 18650 battery $12

I would only need 15 to make a 48v 10ah battery pack?

Am I missing something here because I could sell these?

researching e scooter battery pack

some links would be nice

sla's don't work on these not if you weigh 190lb
a busy cat http://motorcycle.brick7-ca.com/media/ca/1417401_1417500/1417464_81747c176ef702cb.jpg


texts: What is the need for precharging in SRAM/ DRAM memory cell?

texts:
Why is precharging so necessary while preforming read operation on SRAM/ DRAM cells?

For example in the SRAM 6T cell shown below,

Reading 0 requires bit line to discharge to 0;
Reading 1 requires that bit line voltage is equivalent to logic '1' value.

Right?

So why can't this charge (in case of Q=1) occur via M4 and M6?
i.e. why dont we consider M4-M6 as path strong enough to pull up the bit line?

Why do we rely on precharge value to give logic '1' on bit line?

Is it because NMOS M6 is a weak highpass?(due to the fact that NMOS is weak highpass)

Also, In case of precharging, is the precharge voltage = Vdd or Vdd/2 ?


texts:
I am just confused with below statement
"A 100 W bulb is connected in series with a room heater. If now 100 W bulb is replaced by a 40 w bulb, the heater output will decrease !"

if I follow this formula P=I*IR

and believe that 100W bulb will have greater resistance than 40W so if I remove 100W (greater resistance and replace it with low resistance 40W bulb) . the heater should pull more voltage for more output ! Then why it says that it decreases ?

Or in short which one has greater resistance 100w OR 40w and why ?


texts: How can you determine BLDC motor rotation direction as logic high/low by reading hall switches? Not using an MCU, just analog/digital/logic ICs.


texts: Can a computer and its RAM function properly if the temperature of the RAM has been significantly reduced?

texts:
This may be in the wrong section so if it is I apologize.

I'm trying to significantly reduce the temperature of my computer's RAM so I can preserve it's contents during a PC reboot. I read about the method in this paper.

While the RAM is still at about -50 degrees Celsius, is it okay to restart the computer? Will RAM function at that temperature? Or will the cold be electrically inhibiting it in some way?

Also, there's bound to be some spillover to other components of the liquid I'm using. I'm using those standard dust cleaner cans. Will this cause any problems? Also, will the RAM and computer components being wet with that liquid cause any problems?


texts:
I have this circuit
and I have to somehow integrate this into a mobile phone cover. So to power it, I was thinking of using a 3.7v 600mAH Li-Po battery. I want to integrate the battery into the cover in such a way that the cover becomes a rechargeable cover.

As pointed out by Marcus Muller, before deciding on certain core factors of the design, it is important that I mention the requirements for this project.
So:

I am creating an interactive game and I basically want this circuit to act as an input to the game that will be played on a mobile phone.
The circuit has to fit into a mobile phone cover and the push buttons that you see on the circuit are to be placed on either side of the cover. Both buttons have to be pressed simultaneously to create the required action(s) in the game. I already have this part working.
I am stuck between using Bluetooth or a USB connection from the circuit directly to the phone. If I use bluetooth, then I would like the circuit to be powered by a rechargeable battery pack also housed in the mobile cover. If, however, I decide to go with using USB, then I will power the circuit directly from the phone's own battery.
In terms of how long I would like the battery to last between charges: a similar amount of time that a phone battery lasts (if that's any measure to put things into perspective)
At this point, the power source is my main concern. I know that if I choose to use USB then the ATMEGA328p as is will not suffice, as it  has no USB capability.
The main reason that I chose the ATMEGA328p is that I have used it in the past and am familiar with it.
I am not sure what the best solution for this will be; by best I mean the easiest and least complex to implement.

Any assistance will be appreciated.


texts: PCB Layer Stack Dielectric Constant Math

texts:
I have a question reference PCB layer stack and the adding multiple dielectric constants together.

The image and description below should help clarify the question:

The differential pair will be configured in an Edge Coupled External on the top layer, with the signal ground / screen on layer 3.
So the Prepreg (between layer 1 and 2) and the Core (between layer 2 and 3) will form a combined dielectric constant.
I have not included any differential speed as this will be a factor but not important for the question below, more interested in how best to approach the problem which can then be applied to any differential pair in future.  Running the ground on layer 2 is not an option in this case, although it would simplify the problem.

Question: What is the best practice in this scenario for calculating the expected dielectric constant; (1) can we treat this like a series capacitor adding the reciprocals of each, (2) do we simple add them together,  (3) do we add them and then divide to produce a mean value, (4) or?


texts: Where would one find thermal heat sink cases?

texts: I am looking for a case that would work well as a heat sink. Thinking  that something like a car amplifier case? Anyone know where one could find cases like this? Would be using it to house H-Bridges and fill it with thermal conductive epoxy to water proof it....


texts: Is it safe to run esp8266 on 3.76V for long run?

texts: I have made a Circuit for home automation and have discovered that my esp8266 is operating on 3.7--3.8V . I want to ask is it safe to use it at this voltage or I have to step it down to 3.3v for a long run. Note- I am not using a 3.7v battery . It's just a simple circuit that is providing 3.7V.


texts:
I consider using a cheap Microchip 3-pin EPROM with single bidirectional data line as ID storage on various daughter boards.

Since I don't want to waste daughter board connector pins on a device that will be used only once during initialization I was thinking about powering the EPROM from the active-high Reset pin of each daughter board, while using another IO that is unused during init as the data line. After init the reset line goes low and the EEPROM shuts down.
However, for this to work the EPROM need not interfere with normal operation that is it does not draw parasitic current from the IO during normal operation. Can someone suggest a solution?

Edit: the device in question is a 11AA010 with 1mA active current and 1uA standby current as per datasheet.


texts:
I hear of people using FPGAs to improve performance of systems that do things like bit-coin mining, electronic trading, and protein folding.

How can an FPGA compete with a CPU on performance when the CPU is typically running at least an order of magnitude faster (in terms of clock speed)?


texts:
An electrician told me that some companies has really expensive equipment to be able to map how the electrical wiring is structured behind walls and floors.

I wonder, how is this equipment made? What is used to discover the wiring? Does it have to run current through the wire to be discovered?

With this and some programming, I hope to maybe be able to make a similar one myself.


texts: Is there a reason that phase testers are not prevalent in the USA?

texts:
Soft question here. I grew up in Ireland where phase testers (see picture) were used to check liveness of domestic wiring. They were also convenient for checking the ignition in a car.
I never see them used in the USA.
Why not? Grounding issues?
Clarification:
I appreciate the answers, but I am not looking for product suggestions or comments regarding safety unless they pertain to the prevalence question.


texts: Wiring diagram and phase number of three phase transformer

texts: Does anybody have an idea how to draw vector diagram of primary and secondary of a three phase transformer? For instance, if I need to draw vector diagram for Yzn5 diagram and then also draw the winding connections? All I know is that primary is in star connection, secondary in interconnected star and the phase between voltages is 150 degrees (5*30). Also, how to determine this vice-versa (phase number) from an already drawn transformer windings. Is there a good book or internet source covering this field? Thank you very much!


texts: Error converting an array into an integer

texts:
I'm trying to send a number from a PC to a PIC18f4550 as an array using USART and then converting it to an integer using a routine inside the PIC.

The problem arrives that in some cases the integer is not the same number as the array (it's usually 1 unit less) like I show in the image.

#include <18F4550.h>
#include <math.h>
#FUSES NOWDT, XT, NOPUT, NOPROTECT, NOBROWNOUT, NOLVP, NOCPD, NOWRT, NODEBUG
#use delay (clock = 20000000)
#use rs232(uart1, baud=9600)
int count[5]={0,0,0,0,0};
int pulses=0;
int i=0;
int j=0;

void main()
{
 while(true)
   {
      delay_ms(10);
      pulses=0;
      for(i=0; i<5; i++)   //Converts the array into an integer
      {
         pulses=pulses+count[4-i]*pow(10,i);
      }
      printf("P: %u    ",pulses);   //Prints the integer and the used array
      for(i=0; i<5; i++)
      {
         printf("%u ",count[i]);
      }
      printf("\r");
      if(count[4]<9)   //Increases the array in 1
         count[4]++;
      else
      {
         count[4]=0;
         if(count[3]<9)
            count[3]++;
         else
         {
            count[3]=0;
            if(count[2]<9)
               count[2]++;
            else
            {
               count[2]=0;
               if(count[1]<9)
                  count[1]++;
               else
               {
                  count[1]=0;
                  count[0]++;
               }
            }
         }
      }
   }
 }


texts: AVR: do I have to wait for the internal pullup to stabilize?

texts:
speaking of an ATMega2560 (not Arduino!), I connected a simple push-button between PB6 and GND.
There is a bootloader and BOOTRST flag is set, i.e. the bootloader always starts first.
I want to use the button for skipping the bootloader, so I'm going to modify the bootloader:
//Defines for the guard button
#define GRD_PORT PORTB
#define GRD PB6

#define GRD_PIN GRD_PORT - 2
#define GRD_DDR GRD_PORT - 1

//Init guard button as input
cbi    GRD_DDR, GRD   ; clear PB6 in DDR -> making it input
sbi    GRD_PORT, GRD  ; set PB6 in PORT  -> enabling internal pullup

sbic   GRD_PIN, GRD   ; skip next if PB6 is cleared (low) in PIN register
jmp    my_app

But my problem is that jmp is always skipped, i.e it seems internal pullup enabling is slower and PINB6 still remains 0.
Is this valid? Do I have to initialize this port somehow different when using assembly?


texts: Why do letters on a PCB not match those on the back side?

texts:
This is a typical PCB from ebay, front and back side:

The sides are identical, and not mirrored. Which is funny because the A row on the front is the X row on the back.

Is there a logical/practical reason to this, or is it just convenient for the manufacturer to print only one layout instead of mirroring the letters on the other side? I would find it much more useful if the letters were mirrored and could be used to uniquely identify a hole, no matter which side I am looking at the PCB from.


texts:
I am making a PCB where the goal is to keep BOM as low as possible and also the cost to the lowers. It has proven to be quite a difficult task but I am at a final stage now.

My PCB needs to be programmed or interfaced depending on the situation and I do not want to add connectors or get the end user to solder extra wires on so i thought the edge connector would be the perfect option.

I have been looking around and there are thousands of options and I am not sure what the best design would be. My final PCB is 0.8mm thick and 4cm(W)x4cm(H) but could make it larger for this purpose and needs at least 8 pins but more would be great.

First thing that comes to mind is using the old floppy connectors or an ISA slot or even PCI. What should I keep in mind when designing this on my PCB and what would the cheapest connector be?


texts:
Is there any circuit to make incandescent bulbs (60-100W) light up more gradually?
I've seen many different devices but none of them would work for me. I do not want to just stop the high current spike while the filament is warming up. I want the bulb to have 1.5-2 seconds delay before glowing fully bright. My only find is  this Russian video of a light bulb soft start(Sadly I can't just buy it from the Russian store) Most other designs just focus on the inrush current limitation. I want is because I just like the effect of a bulb gradually increasing its brightness.
Can this be done without fancy micro controllers or specialized IC's?
Could you send any schematics that would work?
(The mains voltage in my country is 230V AC)


texts: How to use CMSIS to set up bidirectional Port on STM32F4

texts:
I'd like to use the GPIO_TypeDef an GPIO_Init to create a bidirectional Port on the STM32F407, some input pins, some output pins.

Do I just run GPIO_Init twice, once for the input pins and once for the output pins, after setting up the GPIO_Typedef structure, or does the second run undo everything the first run did?

I know (at least I'm pretty sure) that this can be coded at the register level without problems, but I'd like the CMSIS way of doing things.


texts:
Is it safe to use an Y2 Capacitor where an X capacitor used to be?
I mean Y should be safer right? So Y2 where X should be is OK, but not the other way around, right?


texts: Cable for remote capacitance measurement

texts:
I have an application, where I want to detect proximity of conductive materials (including humans). The idea is that I have a series of conductive sense strips and I measure capacitance between each pair consecutively.

I found an AD7147 CDC datasheet and tested it out in differential mode, seems to work just fine. What troubles me is distance between the sense strip and the IC, which can reach 2m. Obviously cabling should be shielded, IC even provides separate shielding ground pad. Since I'm not interested in absolute value but only dynamic change in measurement, any coaxial cable with fixed capacitance-per-length should do, right? As long as length remains fixed and cable itself is fixed to avoid triboelectric effects.

Are my assumptions correct or am I missing anything? Are there any known issues (possibly from analog accelerometer world) with such a setup?


texts:
I wanted to use HX711 24-bit adc standalone to measure voltage range of 2mv - 20mv.

Problem is:

I cannot interpret the adc readings as it is in 2's compliment.
What should I do in my code (code below) so that it prints voltages not decimal values.

Tried with different values of voltages (shared below), and I am totally confused with the readings I am getting. I don't know how to convert these values in voltage. What is the logic behind. Please help!

Readings:

   0mv  ---  5219,
 1.1mv  ---  5095,
 2.3mv  ---  4981,
 2.5mv  ---  4960,
 2.9mv  ---  4918,
   5mv  ---  4693,
10.6mv  ---  4075,
15.1mv  ---  3597,
22.7mv  ---  2700,
40.7mv  ---   562,
5volts  --- -8388608,
-5volts --- -8388607.

Board is arduino leonardo, and a simple voltage divider is used for voltage generation(for testing only).

A bogde/HX711 library is used: https://github.com/bogde/HX711
Code:

/#include "HX711.h"
/#define DOUT  3
/#define CLK  2

HX711 scale(DOUT, CLK);

void setup() {
  Serial.begin(115200);
}

void loop() {
  long avg = scale.get_value(60);
  Serial.print("Digital Code = ");
  Serial.println(avg);
}


texts:
I'm using STM32F44VET6 controller(using cubemx code configurator), I need to interface a 64GB SD card,and this controller has SDIO pheripheral also

But I'm confused how to choose interface type SPI or SDIO because memory size is high (64GB)

Please suggest  me which interface i have to use to get better speed and accuracy to  read and write?


texts: How would I go about the write port of a set-associative cache memory?

texts:
Let's consider a four-way set-associative cache, just like this one:

As you can see this cache has a read port but there is no write port. I was wondering if you guys could help me figure out how one would implement such a port in this set-associative cache.

I don't think the write method is relevant here, because I'm interested in how a MIPS processor or its memory management unit would write to cache, but if I'm wrong let's say this cache uses the write-back method to write data to main memory.

The book I've taken the picture from also says that caches, rather, SRAMs only have one access port which provides both read and write.

Thank you.


texts: how to convert a Sync-on-green to VGA (seperate sync) signal?

texts:
I have a computer (VAXstation 3100/M76), that has a sync-on-green output:

red          --(
green + sync --(
blue         --(

I want to attach that to a standard VGA monitor, which has RGB signals, and H-Sync and V-Sync on separate signals.

I found several circuits that work the other way round, making a sync-on-green signal from separate sync signals, but nothing that would solve my problem.

Is there an easy way of making a sync-on-green to VGA adapter?


texts: What is meant by the term 'time selectivity' of radio channels? And how is it much faster for mm waves compared to radio waves?

texts:
I was going through an article on channel modelling for 5G communication systems where I encountered the following phrase:

  The time selectivity of radio channels is much faster so that TDD technologies are preferable.

Now what does time selectivity actually means here?
Why is it faster for high frequency signals & How does it make TDD favorable over FDD for > 6GHz signals?


texts: how do you sent a tweet from arduino via arduino wifi shield?

texts:
i used the examples that is in built in arduino to receive tweets. but i wish to receive and write a tweet to a specific account. how do i possibly do that?

i followed the codes from the arduino example.
http://arduino.cc/en/Tutorial/WiFiTwitterClient

but in the codes, it didnt specify where the tweets were coming from. when i run the codes, i received tweets which comes from other tweets which is unknown to me.


texts: Why do I need to use multi drop bus protocol (MDB) in vending machine and How?

texts:
I have a project to build a vending machine but I am suffering from Scarce information about vending machines.

I could find some results :

Inner protocol in vending machine and between the PC is called MDB and is specified by NAMA. This is a protocol between a master (VMC) and up to 32 slave (peripherals) and could be implemented using UART (according to protocol V3 ).
cctalk is another protocol used for coin detector machines.
There are lots of adapters and devices(all of which are closed source) that use this protocol.

According to this information why do I need to use the MDB protocol given that it is finally a UART connection? Why couldn't I use my own language (protocol) especially if I will build all of the peripheral by my self? What are the advantages and disadvantages?

Anyone looking for further information and resources is welcomed to read about either CCtalk or MDB .


texts: How to ensure all nodes on CAN bus have received the message

texts: I know that that the ACK bit will be driven by the receiver of the CAN message. I'm wondering what would the situation be if you have multiple nodes listening to the same message. How would you confirm if all the nodes have received the message, since the ACK bit will only need to be driven by one of the nodes.


texts: What is better, always keep connected or discharge/charge cycles for the smartphone battery?

texts:
My smartphone is serving as internet hot-spot over WiFi for my home/office laptop.
I’m keeping phone always plugged in charge. Most of the day I’m home and using a lot of traffic.
What is the best strategy to prolong Li-ion phone battery life?

Keep always connected?
Full discharge/charge cycles?
Try to keep its state of charge in some range of ⅓ or ⅔?
Use fast or slow charge?


texts: Which adapter is more suitable for a pressure transducer?

texts:
For my student project, I'm going to be using a 4-20 mA and +/- 10 V output pressure transducers and the output of these sensors will be going into a DAQ system that we purchased from DEWESOFT. Along with the DAQ system, we will be purchasing additional adapters that were suggested by the company and I am confused regarding which one to pick.

There is a voltage adapter called DSI-V-200 that takes up to +/- 200 V excitation. It's official description on the website is :
"DSI-V-200 adapter will enable any DSUB9 analog input to accept ±200V voltage range, differential input via BNC connector. Bandwidth and ranges are defined by the connected amplifier."

The other adapter is a current adapter which I believe might be more suitable called the DSI- 20 mA, which is used for direct current measurement. The official description is: "DSI-20mA - 20mA current input adapter with internal shunt 50 Ohm, 0.05% accuracy for sensors with 4 to 20 mA output."

My question is whether voltage or current adapters are more suitable for a 4-20 mA industrial pressure sensor? Can anyone explain whether reading voltage or current measurements from an industrial pressure sensor is more appropriate?

Here is the link to the pressure transducer spec sheet: http://www.futek.com/files/pdf/Product%20Drawings/pmp410.pdf


texts:
From time to time I come across a solution in which uses an LED as in below picture:

This particular component is placed inside the module located in car interior. Button backlight application.

The base LED [PLCC-2 Package] is blue color LED. The top cover material changes the light to white, so I assume this cover material is actually a phosphorus layer. This is a common approach of achieving white color but usually the phosphorus layer is integrated inside the PLCC-2 package (The die is sunk in phosphorus line on below picture.)

What is the purpose of this additional cover?
My guesses are:

Specially mixed phosphorus layer is added to finished LED in order to achieve exact white color coordinates.
Manufacturing process improvement: one line for blue and white LEDs with additional process for white.

Is there any LED expert that could confirm this?


texts:
We recently got licenses for Altium for the teachers and students alike. One question that was raised is the management of the part library. Two options are currently considered. We only have the basic entry license with no add on.

1) Each teacher or group of teacher maintain a library that is specific for a given class

2) There is only one official part library for the department and it would be maintained by one or two teacher to keep it consistent and really useful.

The last time I used Altium was in 2008 so I'm outdated on it. Is there a preferable approach? Do any of you have tips or tricks about it or perhaps some pitfall to avoid at all cost?


texts: Couldn't make State Variable Filter Work

texts:
Me and my friend tried to set a state variable filter to get bandpass output. But neither of us could have achieve it. We both set the exact circuit as in the figure for 10 times in total. We observed low pass rather than bandpass at the relevant output and decrease in the amplitude rather than increase. What might be the problem? We intended to get q=30 and center freq 1k hz.

Note that, we have used lm358 op-amps with +/- 12 Vcc values. R1=R2=R5=R6=10kohm, R7=560k, R3=R4=16kohm, C1=C2=10nF.


texts: Microinstructions: Why is H = H – MDR illegal if H and MDR use two different buses?

texts:
The book here (on page 14) states this:

  Similarly, H = H –
  MDR is illegal too, because the only possible source of a
  subtrahend (the value being subtracted) is the H register.

From my understanding the above statement is saying that the subtrahend (value in MDR) is in the H register? However if you look at this MIC-1 microarchitecture on page 7, the H register connects directly to the ALU and the MDR uses the B bus, so why is it illegal?