texts: How to improve gain of class A amplifier

texts:
I constructed the following two circuits:

Fixed bias amplifier.

simulate this circuit – Schematic created using CircuitLab

Voltage divider bias circuit.

simulate this circuit

Upon experimenting, I found that the fixed bias circuit has more gain and the output is less distorted. In the second circuit, which is actually a stable one as books say, the output gain is very less (I could hear feeble output when I kept speaker close to my ears) and also the output is very distorted. What should I do to get a clear output?


texts: Is there a debugger for Lattice ICE40 FPGAs using ICECube2 for synthesis?

texts: Is there a debugger for Lattice ICE40 FPGAs? Presently, I am using ICEcube2 for synthesis/generating bitmap and diamond programmer to program my devices but would really like to be able to scope into the device. Does Reveal logic analyzer work for these devices? If so, how do you use ICEcube 2 to generate the proper files?


texts: How to correctly send the data I received via I2C over UART?

texts:
I am using an atmega328p and writing firmware to display the data I receive via i2c in putty.

I read the data I receive as follows:

/* Receive data from slave. */
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
while(!(TWCR & (1<<TWINT)));

libuart_send((char*)TWDR,1);

where:

 void libuart_send(unsigned char *data, int data_size)
 {
    for(int i = 0; i < data_size; i++)
    {
        /* Wait for empty transmit buffer */
        while ( !( UCSR0A & (1<<UDRE0)) );

        /* Put data into buffer, sends the data */
        UDR0 = data[i];
    }
 }

I can see with my logic analyzer that I receive 0x00:

Yet when trying to see the corresponding data with putty, I just get a weird symbol as if I am casting it incorrectly:

I have been trying to find out how the register TWDR is defined in order to try to understand whether or not I am casting something incorrectly, but I didn't find the information I was looking for. Note that my function libuart_send works perfectly fine when I do something like this libuart_send('A', 1);, but not when I replace the first argument by TWDR. In other words the baudrate is perfectly fine.

Does anybody know why I am seing this weird character in stead of the number 0 in putty?

Thanks


texts: How to connect low power components to high power component?

texts:
I have a fairly standard circuit: I am controlling a 12V starter motor + 12V car battery with an Arduino PWM signal. I have an array of 4 MOSFET's to connect the low power circuit (Arduino) to the high power circuit (car battery). The low power circuit has 20AWG wire and the high power circuit has 4AWG wire, as I expect about 100A. I've never worked with anything beyond logic levels, really.
My problem is in mechanically/electrically connecting the MOSFET pins: The Drain and Source pins seem too small to connect to 4 AWG, and I couldn't solder them onto a perforated circuit board, as it cannot handle the heat generated by the current.
Is there a specific mounting component I can use to connect Gate to a low power circuit and Drain and Source to a high power circuit?
TIA!


texts: opamp heating in voltage controlled current source

texts:
Well, I have a serious problem with heat in my circuit. I was trying to build a voltage controlled current source. Everything went fine in the building process. But when I turn ON the power supply the TIP122 gets very warm and so do the IRF820. I know this guys tend to get hot when dissipating some considerable amount of energy, however, my circuit just intent to deliver some hundreds of mA. And the main problem: the TDA2822 is getting very hot. Hotter than all the transistors together. Although all that dissipated thermal energy, the circuits works pretty well TBH.

Any help is appreciated!
Cheers.


texts:
I got this old electric motor from a friend of mine, and I don't really know the right way to connect it to electricity supply. It's a IMEX (type = YC112M-4) motor.
I've tried to look for the wiring diagram on Google, but I couldn't find any.
Could someone help me, please?


texts: RF FETs - how exactly are they different from regular FETs?

texts:
I've browsed through DigiKey and there are these RF FETs. Are they for final stage amplification? Say you have an opamp that doesn't go for the final desired voltage, so one uses these FETs as Common amplifiers?

Is that why they are rated with gain and frequency in the page, rather than Transconductance and rise/fall times?


texts: Basic questions about output impedance of a logic inverter using an NMOS

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I have drawn below an NMOS logic inverter and its equivalent circuit for HIGH state:

1- Why is this gate said to have high output impedance at HIGH state? Is that because of the open switch or because of the resistor R’s value?

2- Why having high output impedance lowers noise immunity? Is there a relation between output impedance of a source like this gate and interference picked up? Im trying to make sense why high output impedance lowers the noise immunity.


texts:
Project: 8 channel quiz buzzer circuit using 8051 microcontroller from this site.

For the first candidate who presses their button, their number will show on the 7-segment display and the buzzer will make a sound.I am using peizo-buzzer in the circuit.

After making all the connections, the display is working but the buzzer is not making any sound. Buzzer delay time in code in 1ms. When we give direct 5V supply to the buzzer it works, but not in the circuit.

Please give me some solution for this.

#include<reg51.h>

#define SEGMENT P2 // PORT2 to Segments of 7-Segment Display
#define SWITCH P1  // Input Switches (buttons) to PORT1

sbit buzz=P3^0; // Buzzer
sbit rst=P3^3; // Reset Switch (Reset the display) - not the microcontroller
sbit digit=P3^7; // 7-Segment Display Common Pin (to enable)

void delay (int); // Delay function

int x=0,y,z;
unsigned char ch[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x98}; // Hexadecimal values from 0 to 9.

void delay (int d)
{
    unsigned char i;
    for(;d>0;d--)
    {
        for(i=250;i>0;i--);
        for(i=248;i>0;i--);
    }
}

void main()
{
    SWITCH=0xff;
    SEGMENT=0xff;
    digit=1;
    buzz=0;
    rst=1;

    while(1)
    {
        while(SWITCH==0xff); // wait until any button is pressed.

        while (SWITCH==0xfe) // Button 1 is pressed.
        {
            SEGMENT=ch[1];
            buzz=1;
            delay(1000); // Activate buzzer for 1 second.
            buzz=0;
            while(rst!=0); // display the digit until the reset is pressed.
        }

        while (SWITCH==0xfd) // Button 2 is pressed.
        {
            SEGMENT=ch[2];
            buzz=1;
            delay(1000);
            buzz=0;
            while(rst!=0);
        }

        while (SWITCH==0xfb) // Button 3 is pressed.
        {
            SEGMENT=ch[3];
            buzz=1;
            delay(1000);
            buzz=0;
            while(rst!=0);
        }

        while (SWITCH==0xf7) // Button 4 is pressed.
        {
            SEGMENT=ch[4];
            buzz=1;
            delay(1000);
            buzz=0;
            while(rst!=0);
        }

        while (SWITCH==0xef) // Button 5 is pressed.
        {
            SEGMENT=ch[5];
            buzz=1;
            delay(1000);
            buzz=0;
            while(rst!=0);
        }

        while (SWITCH==0xdf) // Button 6 is pressed.
        {
            SEGMENT=ch[6];
            buzz=1;
            delay(1000);
            buzz=0;
            while(rst!=0);
        }

        while (SWITCH==0xbf) // Button 7 is pressed.
        {
            SEGMENT=ch[7];
            buzz=1;
            delay(1000);
            buzz=0;
            while(rst!=0);
        }

        while (SWITCH==0x7f) // Button 8 is pressed.
        {
            SEGMENT=ch[8];
            buzz=1;
            delay(1000);
            buzz=0;
            while(rst!=0);
        }

        SEGMENT=0xff;
        rst=1;

    }
}


texts: Need help with boost converter for solenoid

texts:
I have a pull-solenoid with 32 ohms of resistance. I would like to supply 1 Amp to it with a 1 cell lipo battery: 3.7v nominal, 15 amp draw, 720mah. The power draw only needs to last for a fraction of a second to actuate the piston on the solenoid.

Using pspice I found that charging the solenoid by itself and then opening a switch to force the current through a zener diode forced the voltage to rise to the breakdown voltage of the zener because of flyback effect from the inductor. I then tried to use a TIP102 to allow a path for the 1 amp to flow but have had no luck.

With the TIP102 in the circuit, the voltage on the zener doesn't spike nearly as high and the current into the base is less than before the switch opens and little current enters the collector.

Battery through inductor with switch opening after 1us. When the switch opens, the voltage across the inductor increases until it reaches the breakdown voltage of the zener, in this case 30V. This is shown correct in pspice sim. The theory here is the inductor will create enough voltage potential in the circuit to pull an amp through itself.

When the flyback voltage rises to the breakdown voltage, current enters the base of the TIP102 and a large amount of current can flow into the collector

Edited for more explanation


texts: Connecting Headphone to Phone and Laptop via Switch

texts:
I am trying to build a small circuit which will connect my phone, laptop and headset with a switch.
So in state 1, the headphone and phone will be connected
and in state 2, the headphone and laptop will be connected.
Just DIY stuff so I need not frequently disconnect/connect headphone from/to each device.
The circuit will have three female audio jack with connection shown in diagram(did not get the right tool. so its not much appealing but gives the over all idea)

The headphone which I use has 3.5mm TRRS jack so which translates as
Tip     --> Left        --> L
Ring    --> Right       --> R
Ring    --> Ground      --> G
Sleeve  --> Microphone  --> M
Question:
Which of the below approach can be used?

Connect(Short) every terminal except ground to every other female jacks and toggle ground between headphone/phone and headphone/laptop.

Here I realised that connecting R,L of Phone to R,L of laptop might be
an issue as R,L is output port and here I am trying to connect a output of
two device back to back. So I came up with point 2.

The connection as mentioned in the diagram. The DPDT switch will toggle R,L between two device and the other will be isolated. This will solve the issue in point 1 but is it okay to connect ground of phone and laptop at all time?

Mic is not a problem(I feel so) as it is always a input port and doesn't matter if my laptop gets the input when I am talking over Phone.
I am confused on which approach I should use and do the circuit and also not blow up my laptop or phone audio device.
Also I would like to hear if there are any other factors to be considered for this circuit.


texts:
I have a buck converter that is delivering 6A to a load of 3ohm load.

I'm measuring the output current and stop increasing the dutty cicle when the current reach 6A, at this moment the output voltage will  be 18V. A few second after reaching this point the resistance will break and I will have and open circuit at the ouput.

simulate this circuit – Schematic created using CircuitLab

My concern is the following, the inductor's current can't change inmediatly, I guess I'll go to the capacitor increasing the output voltage, It is a risk to damage the power supply or the driver circuit because of a backward current?

I'm using a IR2110 to drive the transistor.

Edit:

R1 is a heating wire, I'll use it to control the ignition of a small rocket, so at the moment of the ignition the wire will break and the inductor will be is series with the capacitor.

Now, I just made this calculations:

$$ capacitor \ energy  = 0.5*C*V^2 $$

$$ inductor \ energy  = 0.5*L*I^2 $$

$$ L = 43uH \ , \  I = 6A $$
$$ \ C = 800uF $$

$$ inductor \ energy  = 0.001548 $$

for 0.001548 joules I get:

$$ \Delta_V = 2V $$

Is It that an accurate estimation?

Edit 2:

Is this scenario of removing the load different than operating in discontinuous conduction mode? where the current ripple is high and adsorbed for the capacitor.


texts: UL/CE/CSA certification for low voltage electronics/LED product?

texts:
I am working on a fairly simple LED product that would use an external power supply (12V). Certain configurations of the product may require more than 100W. I could also configure the product to use 24V.

Are Class 2 power supplies my limit before requiring CE/CSA certification? Or is there a voltage/power limit before legally requiring CE/CSA certification?

Thanks in advance.


texts: Anyka AK1120Q - 'Mobile Application Processor', Spy Cam, cheap cam-corder?

texts:
I've been trying to learn more about my spy-cam. I opened it up, and found that it has a Anyka AK1120Q IC. I found a datasheet for the: AK3671B but it took a lot of searching.

Why is it so hard to find information on these IC's?
Is there an alternate IC I can use if I wish to rig up my own camera from scratch (low cost). I'd like 720p video as well. Maybe get it to stream to my laptop..
I found a Broadcom BCM2727 chip  but as usual the datasheet was hard to find - i found lots of marketing crud. Also, ebay doesn't seem to be selling these IC's loose. In fact I couldn't find a single web-site actually selling any of these IC's but I can find plenty on the IC555. Why is this? Am I googling for the wrong thing? What do I google for?
Are there any books/resources (besides the wiki) on this subject that I should check out first?

Basically i'm trying to figure out what I need to know in order to build my own Camera (with the help of modern chips[for a reasonable cost] - i'm not dead keen on reinventing the wheel just yet - i know reading from a CCD is quite difficult)


texts: Total capacitance for a ladder network with two capacitances

texts:
Is there a standard formula to determine the total capacitance of:

simulate this circuit – Schematic created using CircuitLab
Where C1 and C are different capacitances and for n number of C1 and C.
Maybe one can create an equivalent circuit design, but I can't quite see it.

Thanks!


texts: 5.5W 450nm China laser diode driver problem

texts:
I have a Chinese 5.5W diode laser which I gave 5V on the 12V pin. The power LED was blinking but I didn't care because I didn't know what that means. After some time, the LED stopped blinking and the circuit is not turning on even if I give it 12V.
I found one component that seems to be burnt but can't figure out what it is and what is the model number. Here is a picture of it.

Can anyone help me find the problem and how to fix it? I am designing a corexy plotter+laser engraver for a student project and the deadlines are very close.


texts:
This is a fairly specialised topic about DAC capacitor arrays for SAR ADCs. In particular, this charge-redistribution DAC is of a split-capacitor type.

I'm having some difficulty understanding the operation of it. The paper I reading is https://ieeexplore.ieee.org/document/4140585

Here's my understanding:

In the "sampling" block in the flow-chart above, both the main subarray of capacitors and MSB subarray get ground on their positive top plates and get Vin on their negative bottom plates. Thus, both capacitors charge up such that a voltage difference of -Vin is present across them (top plate (+) - negative plate)
We move to the "Start Bit-Cycling" block in the flow-chart. All capacitors have Vin on their negative plates. The bottom (negative plates) of the MSB sub-array capacitors only are now connected to Vref.Thus, the top plate of these sub-array capacitors will change by (Vref-Vin). Charge redistrbution occurs since top plates of main-array is at 0. The capacitors now settle at (Vref-Vin)/2? I'm getting confused here. What happens exactly after bottom plates of sub-array capacitors are connected to Vref?


texts: Modulate/demodulate 125khz signal to 433Mhz transmitter module (2.5Ghz carrier)

texts:
I am trying to implement a project which consists of two circuits. Circuit A receives a 125khz AM signal and modulates it to 433Mhz CC1101 which then uses 2.4Ghz carrier to send at longer distance. Circuit B receives and demodulates the 433Mhz signal back into original 125khz. I am using AS3933 for receiving 125khz LF signal and CC1101 to transmit the signal at higher frequency. The core of the project is Arduino Uno.
The signal path I'm hoping is for goes like this:

(Circuit A) 125 kHz -> AS3933 -> Arduino -> 125khz to 433Mhz modulation -> CC1101(2.4Ghz)-> 2.4 GHz -> (Circuit B) CC1101(2.4Ghz)->Arduino-> 433Mhz to 125khz demodulation -> some 125khz signal modulation using coil antenna

I am wondering how do I design modulation/demodulation circuit for 125khz to 433Mhz?

Here are the datasheets:

CC1101

AS3933

All help is greatly appreciated!


texts: How should I check USB signal integrity?

texts:
I'm using 2 USB hubs chained together to hook up my phone to the computer to do some testing stuff. How can I check if the USB signal is being good or not? I tried scoping the USB pins with the USB hubs connected and disconnected. Both cases had the Data+ pin around 500 mV, is this good? The waveform looks slightly different, with the signal with the hubs connected having more spikes.

Can someone refer me to a good site that covers the USB protocol? How do you know if the signal is good enough?

EDIT: I'm using a Tektronix VM 5000 HD. What voltage range should I expect to see at the Data+ pin?


texts: Enabling Pins on the Adafruit Motor Shield V2

texts:
I have soldered together an Adafruit Motor Shield (Version 2) following these instructions for standard headers (non-stacking headers).  The end result looks similar to the image below:

I'm hooking the shield to an Arduino Uno and I want to hook up some sensors to this shield as well.  Unfortunately, the standard headers that I've soldered on don't allow me to do this.  I see two rows of holes next to the ones I've already soldered, numbered 0-13 on the digital I/O and 0-5 on the analog I/O.  Can I solder female headers onto these holes in order to enable them?  Are there any pins that I can't/shouldn't use?  I've heard a rumor that the motors use up some of the pins, but I can't find any information as to which pins to avoid, specifically.

Any help would be greatly appreciated.


texts:
I'm trying to program ESP8266 Node MCU v0.9 using Arduino IDE. I'm trying to upload the most common sketch i.e. blink which is available in the examples of ESP8266. Even then I'm getting this error -

    Arduino: 1.8.11 (Windows 10), Board: "NodeMCU 0.9 (ESP-12 Module), 80 MHz, Flash, Legacy (new can return nullptr), All SSL ciphers (most compatible), 4MB (FS:2MB OTA:~1019KB), v2 Lower Memory, Disabled, None, All Flash Contents, 115200"

    Executable segment sizes:

    IROM   : 227612          - code in flash         (default or ICACHE_FLASH_ATTR)

    IRAM   : 26776   / 32768 - code in IRAM          (ICACHE_RAM_ATTR, ISRs...)

    DATA   : 1252  )         - initialized variables (global, static) in RAM/HEAP

    RODATA : 672   ) / 81920 - constants             (global, static) in RAM/HEAP

    BSS    : 24880 )         - zeroed variables      (global, static) in RAM/HEAP

    Sketch uses 256312 bytes (24%) of program storage space. Maximum is 1044464 bytes.
    Global variables use 26804 bytes (32%) of dynamic memory, leaving 55116 bytes for local variables. Maximum is 81920 bytes.
    esptool.py v2.8
    Serial port COM13
    Connecting........_____....._____....._____....._____....._____....._____.....____Traceback (most recent call last):
      File "C:\Users\Tejashree\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.6.3/tools/upload.py", line 65, in <module>
        esptool.main(cmdline)
      File "C:/Users/Tejashree/AppData/Local/Arduino15/packages/esp8266/hardware/esp8266/2.6.3/tools/esptool\esptool.py", line 2890, in main
        esp.connect(args.before)
      File "C:/Users/Tejashree/AppData/Local/Arduino15/packages/esp8266/hardware/esp8266/2.6.3/tools/esptool\esptool.py", line 483, in connect
        raise FatalError('Failed to connect to %s: %s' % (self.CHIP_NAME, last_error))
    esptool.FatalError: Failed to connect to ESP8266: Timed out waiting for packet header

    This report would have more information with
    "Show verbose output during compilation"
    option enabled in File -> Preferences.

I Checked the COM port, drivers and libraries needed. Everything looks just fine. I don't understand where it is going wrong. How to get rid of this error?


texts:
The input to a L.T.I. circuit is \$x(t) = 6\cos(t)\cos(3t)\$, and the impulse response of the circuit is $$h(t) = \frac{\sin(3t)}{3t}$$ Obtain an explicit expression for the output y(t) as a function of time. The fourier transform of \$x(t) = \$

$$\sum_{n=-\infty}^\infty C_n e^{in2t}$$

I converted \$h(t)\$ to  $$H(iw) = \frac{\pi}{3}\times\text{rect}\left(\frac{w}{6}\right)$$

However, I am confused on how I would use Fourier series coefficients to solve this problem.


texts:
I have a motorcycle headlamp that I am lighting outside of a motorcycle. It's a stage prop, I have the front end of a motorcycle built as my microphone stand. The bulb has hard set 3 terminals, two leads and 1 common out. I am wanting to put a blinker on one of the lights (high beam) and have a switch just for on and off on the other light (low beam).

I am wondering if I am running into a problem where the common terminal on the light comes out and I have to split the cable to run to the two negative terminals. Will the current split and distribute amongst the two? Will this work ok? I have the two power supplies to provide enough amps to run both of the lights. By the way, this is DC Current. Thanks so much for your help.

simulate this circuit – Schematic created using CircuitLab


texts: What microcontrollers can utilize 30-52MBit RS-485?

texts:
I am rather new with micro controllers, please, push me in the right direction.
I'm planning to use RS-485 network for audio streaming at home. On maxim-integrated site there are drivers, which have throughput of 30-40 or even 52Mbit. But I wonder, what MCUs should one use to get such speeds? UART is several times slower even on ARMs. Atmega's have no chance. What hardware should I use? Global idea is to connect every speaker at home to separate MCU and to get a very versatile multi-room. Mostly it will broadcast 1 stream of CD-audio quality (1.5MBit), but it will be good to have reserve for couple more and maybe low quality video one day.

Of course, the biggest priority is price, so I plan to make PCBs and solder everything by myself. Bunch of raspberries + ethernet is NOT an option. I think it will be an overkill and too expensive.


texts: How to drive a speaker (earpiece) in an antique (vintage) phone (67 ohm)

texts:
I am using a small audio player board (DFPlayer Mini) that has a 3w audio amplifier built in.  I have hooked it up "as is" and it appears to work but has some intermittent static.  While it could be due to a loose wire, in the process of checking it out I noticed that the impedance is 67 ohm, not the typical 4 or 8 ohms.

Is there any circuitry I should add to protect the audio player and/or speaker?


texts: Thread-Style Operation on Microprocessor

texts:
This is a general question about designing firmware for AVR microcontrollers, say, the AtMega16.

I have a routine that I am running through several thousand times per second. The routine is entirely interrupt driven outside of the main loop. I can still run code in the main loop, but it takes too long to operate with several thousand interrupts a second.

I would like to have a routine that scans for incoming data and modifies a variable that the interrupt-driven routine uses. This routine should be asynchronous to the interrupt-driven loop. The variable(s) will change whenever the second routine is ready. Until then, the interrupt-loop should continue running as it was before.

Imagine two processors that share direct CPU access to a common variable. They are both doing different jobs, but one reads the state of the other over the variable. Is there any way of simulating this setup on a single processor? I understand I may have to sacrifice processing power/speed for each routine to make this possible, but my interrupt-driven routine will naturally react to how fast the CPU can run it.


texts: Li-Ion battery over discharge protection

texts:
I'm designing a Li-Ion battery charger circuit with a bq24702 chip. I will use it with two Li-Ion batteries connected in series. In order to protect the batteries from over discharging, I have to know, when is the battery discharged. I will use Tensai Li-Ion TR-26650LI batteries. In the specification is written: "When discharged at 0.2C to 2.75V at 20°C". Does this mean, that it is not recomended to discharge a battery cell under 2.75V?

This would mean, that I could only use the battery between 0.2C and 1C, so I could use effectively 4500 mAh - 900 mAh = 3600 mAh. This would be not sufficient for me.


texts: How many of these UV lamps do I need for PCB fab?

texts:
I want to build a PCB UV exposure unit. It will be in a wooden box, it will have lamps and a glass above them. Basic design.

For the lamp drivers I will use the circuit from the neon lamps at home. Turns out it works to drive them too.

I have found these lamps on eBay.

How many of these do I have to buy to have a good fabrication unit? And how do I calculate the exposure time with regards to how many lamps I have?


texts: LED resistor calculation with variable voltage

texts:
I apologize as the original question was not accurate.  I have updated the question.
My main goal is to design a polarity tester for battery packs. It will be used for multiple ranges of batteries to test their polarity. So the battery's voltage starting from 3.5 volts to 60 volts with different output current. The schematic below shows the exact diagram and PCB I made with Fusion 360.
I want to calculate the value of the resistor. The LED forward voltage is 2.5 volt, and the current of LED is 130 mA. 2.25 V Red LED 5mm Through Hole, Kingbright L-53HD.
The power source is variable from 3.5 volts to 60 volts with the variable unknown current. So, each time I connect the circuit to any voltage from 3.5-60 volts one of the LEDs will turn on. The problem is that as the source voltage is variable what type of resistor I need to resist the variable voltage so the LED does not burn.
I used 4 diodes, to block and allow the current for two LEDs, from one side one LED with green colour will light up and it will show that the polarity is correct. If the polarity is wrong then the red LED will light up.
I used U1 as a Bourns 1kΩ Thick Film SMD Resistor ±1% 25W - PWR163S-25-1001F for dropping the voltage. I know this might not be suitable but as the problem, I have with different voltage I thought this might work.
The power for the circuit will be taken from the battery packs and there will no external power supply for the circuit board.
On circuit "JP3" and "JP4" are circuit power input, JP1 and JP2 are LEDs.


texts: Can someone please help me to dissect this active op-amp circuit? I'm trying to find the output voltage at varying frequencies.


texts: Erratic behavior from 16-bit counter IC SN74LV8154

texts:
My test circuit is shown below.  I've tried various configurations but keep getting jumps in the output counts.  Seems to be repeatable and consistent.  For instance, the first jump always occurs around 7k-8k counts.  I saw another post where the problem seemed to be with power supply filtering.  I've tried many different filtering caps on my regulator output, the register clock signal and the counting clock signal.  Advice would be greatly appreciated at this point.

Arduino code can be reviewed here

Arduino Output:

UPDATE

Scope trace for RCLK input:

Scope trace for CLKA input:

5V supply with 555 running:

5V supply without 555 running:

UPDATE

Tried replacing the counter chip with a new one and got the same result as before.  Also, when I slowed down the input signal to 10 Hz I was able to see that the first jump occurred between decimal 8114 and 8150.  The first decimal value after the jump was 16390, almost exactly double!

00011111 10110010   Decimal: 8114 <-- Count before fault

00011111 11100100   Decimal: 8164  <-- Expected Count after fault

01000000 00000110   Decimal: 16390  <-- Actual Count


texts: Mini PC stick can be powered with mains power adapter (5 V/2 A) but not with power bank (also 5 V/2 A)?

texts:
I bought this product with the hopes of powering it with a power bank:

https://www.intel.ca/content/www/ca/en/products/boards-kits/compute-stick/stk1a32sc.html

https://www.amazon.ca/gp/product/B0868JZGPB

Now with its mains power adapter it works fine. The mains power adapter says it outputs 5 V/2000 mA.

So I figure why can't any of my power banks, with provide 5 V/2 A (or 2.1 A) power this mini PC? Tried with 2 different banks, both with 5 V outputs. Both can charge phones and do other things fine.

What happens is I plug them in to the power bank, then it seems to turn blue/lights on for a bit, but then it turns off after a few seconds and never boots up.

Any ideas why this would happen? Any other ideas how can I power this thing with a power bank / not a mains power adapter? That's specifically why I bought it.

Thanks.


texts: automotive: 2 relay circuit with extra double pole switch

texts:
I have this hydronic parking heater. When I run it I can heat the coolant circuit with the engine OFF.

I found an upgrade kit from Webasto for my van which let's you install a 3-way solenoid valve in the engine bay controlled by 2 relays. This modification allows you to bypass the engine block, heating a smaller circuit, so the cab matrix gets up to temp quicker and more efficient.

The conditions for the valve to be energised are:

heater ON
engine (ignition) OFF

Now I wanted to be able to manually switch between small and big coolant circuit myself. For example:

I want to heat up the engine block before going to work with my
digital timer (big circuit)
When waiting in the van I only want the
cab to heat up quickly (small circuit)

  So I was thinking to put a switch in the (+) blue wire {7}

What I don't seem to like about this Webasto circuit is the K2 relay. If the ignition comes ON, the relay breaks the negative to the valve, but what if the relay fails??
I absolutely want to make sure I run the coolant circuit through the engine block with the ignition ON!!
* I know that the heater comes on automatically when driving in <5°C outside temp,  so this is a situation where I don't trust the K2 relay..

    So I was thinking some more.. what if I put a double pole switch (DPST) in the (+) blue wire {7} and the (-) brown wire, somewhere?
    Maybe in wire {6} or even {3} that last one would break all relays right?

Good thinking?
My manual switch would only come on when waiting in the van, getting toasty, right?
All other situations I would be confident I will not ruin my engine?
Any other suggestions?


texts: Circuit Wizard NE555 astable circuit weirdness

texts:
I am trying to understand the NE555 IC in astable mode, I prototyped a circuit using "Circuit Wizard" student edition as shown in this video http://www.youtube.com/watch?v=SX01x1z7fTY at 05:36 (screenshot below) but strangely my version doesn't go in astable mode but only flashes once.

It seems like pin 7 never discharges the condensator (I tried varying the resistance but it has no effect, what is strange is that my circuit is identical to the one on the video).

Below the youtube version and mine, one flashes the other not. Do I have to set some weird setting in Circuit Wizard or is it some bug in my version?

EDIT: the dots in red, blue, green and purple is where I have put the probes and the logical levels are superimposed below the circuit.


texts: How to claculate LM-723 regulator circuit headroom above the intended output voltage

texts:
I need to calculate the transformer VA for bipolar regulator circuit using LM723 so I need the voltage drop or may be a headroom for LM723 under load. The data sheet is silent about it. Is there anybody who had an experience building LM723 based PSU to answer this question?

Here is the schematic of circuit:


texts: I have been taking apart a old television circuit board and I found several of these things. They look like resistor but when I test them with the multimeter the resistance is very low, around 10 to 20 ohms.


texts: What can cause voltage irregularities across an IC chip?

texts:
This is the preamp section of a channel of a tape deck for which one channel is working and one is not.  Swapping all the components between the channels does not affect which channel is working correctly, so presumably the components are all functional.
Measuring the voltages across the IC chip on the good channel, the values are as in the schematic, while the values for the chip on the bad channel values are zero for pins one through five and around one for pins six and seven.
If there are no faulty components in a circuit, what else could cause voltage irregularities across an IC chip?


texts: Why a lower/higher than resonant capacitor is required in tesla coil design?

texts: People are telling me that the primary tuned LC circuit should have a capacitor a little higher or lower than resonance, but not at it. Why is this the case? Don't you want the most power you can get?


texts: Looking for possible cause for poor regulation in self designed transformer

texts:
I am trying my hand at designing and winding my own ferrite transformer for a push pull 1000watts dc-dc converter from 10-12vdc to 400vdc, with copper foil of 0.3mmx30mm for the primary, and copper wire of 0.8 sq mm as secondary.  My core is an EE55 using the following:
Turns details: 1+1 primary, and 50 turns secondary.
Actually the primary is more than 1 turn and less than 2 for each leg. I have considered it to be 1+1 turn, since I have got the desired turns ratio and voltage on no load.
Inductance: Primary 311uH primary open, and 21uH leakage. Secondary 6mH, with 6uH leakage.
I am driving the circuit using a micro-controller, with 50KHz hard switching for the MOSFETs. The driver MOSFETs are IRF540N, four in parallel on each leg of the push pull.
At no load my primary current is about 1 amp (as read on a DMM), and this rapidly drops to 18 amps on a 200watt incandescent bulb load, measured on a 100 amps dc shunt ammeter.
I am using a fixed 49% duty cycle, and the output voltages and currents are
1. 800volts at 1 amp primary current on no load.
2. 550vdc at 2 amps primary current on 15 watts load.
3. 458vdc at 4 amps on 40 watts load
4. 446vdc at 6 amps on 60 watts load
5. 410vdc at 9 amps on 100 watts load
6. 390vdc at 10 amps on 115 watts load
7. 355vdc at 12 amps on 140 watts load
8. 324vdc at 14 amps on 160 watts load and
9. 287vdc at 18amps on 200 watts load
All loads are incandescent bulbs.

My output diodes are MUR460, which are high frequency diodes, and my o/p cap is a 200uF 450VDC electrolytic.
I run the entire circuit on a single sided paper phenolic pcb that I have designed. The primary tracks are very wide (10mm) as well as have about 0.5mm lead coating on them to allow for more current flow. The secondary tracks are 2mm width with lead coating
I am unable to find the cause for such poor regulation at such low loads, and would appreciate some pointers to help me correct my design and improve its performance.


texts: How to find these resistance values in microphone phantom power power supply?

texts:
In most phantom power supply schematics or documentation (see for example https://en.wikipedia.org/wiki/Phantom_power#Technical_information), I see:

6.81 kΩ when powered by 48V
1.2 kΩ when powered by 24V
680 Ω when powered by 12V
470 Ω when powered by 10V
sometimes (but not sure if correct) 180 Ω when powered by 9V

Question: how to find these values, what is the formula being used?

Attempt 1: Obviously, it's not a direct application of Ohm's Law, because:
48 / (6810 / 2) would give 14 mA to the microphone (I divide by 2 the resistance  value because there are two same resistors in parallel)
12 / (680 / 2) would give 35 mA to the micrphone, which is very far to what the linked page above states:

  The IEC standard gives 10 mA as the maximum allowed current per microphone

Attempt 2: We could imagine there's an "equivalent" resistance for the mic (maybe impedance).

I tried to find the value Req such that V_i/(R_i/2+Req) is close to each other for each of the 5 cases (i=1..5) mentioned above. 650 Ohm seems to work:

48/(6800/2+650)=11.9 mA
12/(680/2+650)=12.1 mA
10/(470/2+650)=11.3 mA
9/(180/2+650)=12.2 mA

but unfortunately:

it's not coherent with the 24V case: 24/(1200/2+650)= 19.2 mA! which is too much
12 mA is higher than the IEC standard mentioned above, so I can't imagine they created a standard schematic based on a too high current


texts: Using RF Link Transmitter/Receiver - ADC vs Microcontroller?

texts:
I have a sensor that gives off 4 volts when actuated and I would like to transmit it a distance to a light.  So I found these RF Link Transmitter/Receiver at 434MHz:

https://www.sparkfun.com/products/10534
https://www.sparkfun.com/products/10532

The data sheets and instructions I've read all suggest a microcontroller.  What I'm asking is this:

For the transmitter side of my project (sensor that gives off 4V), could I use an Analog/Digital converter instead of a microcontroller to convert the 4V? Would the transmitter send that signal?
I do have an Arduino Yun that I could use for the receiver side, but lets say I didn't have an Arduino, what would I be able to use to convert the data from the receiver? A Digital/Analog Converter?
Last Question: Would I need multiple transmitters/receivers for multiple sensors?

Thank you for your attention and any insight would be greatly appreciated.  Thanks again!


texts: constant independent of time, meaning of this line?

texts: can someone please explain last paragraph in the Picture that i have uploaded, in layman's term specially this phrase "constant independent of time"


texts: How to ensure DC input stays positive regardless of a positive or negative voltage input?

texts: What is the "most" correct way to deal with a DC source that can have a +/-input voltage? For example I have a hand crank generator. Spinning the handle one way generates 0 to +20 volts, spinning the other way creates 0 to -20. I need to insure its always positive regardless of hand crank direction. My first thought was a configuration of either diodes or transistors. I assume there is a standard way but i'm not sure what term to google.


texts: Current source as load in a differential amplifier

texts:
In Design of Analog CMOS integrated circuits by Razavi I found the following differential pair design. It uses a MOS as load and it acts as a current source.

My question is how should you bias the current source loads? My initial guess would be that M3 and M4 should be biased so that the current through them is Iss/2, because this is the current that also goes through M1 and M2 when Vin = 0.

Now comes the bit where I become confused. As far as I know differntial pairs are designed so that when the maximum input voltage is supplied one of the transistors (M1 or M2) is fully on and the other one is fully off. This was the case with differential amplifiers that have a restive or diode connected mosfet as load.

However, with current sources as load this will cause a current conflict between the differential pair en the current source loads. For example: The maximum input voltage is applied and therefore M1 is fully on and M2 is fully off. Now M3 should  supply Iss since M1 is fully on, but its source and gate are fixed so it is limited to Iss/2. Furthermore, M2 is fully of, but M4 tries to force Iss/2.

So what am I missing? Why does this circuit work?


texts:
I'm trying to make a temperature controller for peltier module using MOSFET. The peltier uses 3.3 to 12 volts and 15A. So far I've only come across a way in which the circuit uses a potentiometer at the gate & drain to control the MOSFET source output. I'm looking for a way in which the microcontroller can automatically control the voltage from a feedback loop. I've come across some digital potentiometers but they can't handle 15A. Any help?

By the way, I'm not an electronics engineer. Thank you.


texts: Is my ultrasonic cleaner using a common mode choke as an AC to DC converter?

texts:
I am repairing an ultrasonic cleaner with a faulty circuit board. It has a blown out diode and capacitor that needs to be replaced.  The board, however, has me curious and confused as to its function. I drew out the schemtic to the best of my abilities.

The large coil is a common mode choke according to its datasheet.  It’s intended for filtering out high frequency noise, which is makes sense. There other boards drive the ultrasonic transducers at around 40 KHZ which may create interference.

The choke, diode and capacitor, however, appear to be stages in an AC to DC conversion. The choke is center tapped and rectified using only two diodes. This puzzles me since the choke’s datasheet only discusses its use for  noise filtering.

Is the board both a DC filter and  AC to DC converter? If so, shouldn’t the filtering be done after the AC to DC convention. Also, why would anyone want to use a choke instead of a transformer? I was under the impression that they were simple coils, not full blown transformers. Finally, not sure I drew it correctly, but what's the purpose of the two caps connected to ground?


texts:
I have attached the timing diagram. I want something similar to monostable multivibrator but with so additional features. don't know how the circuit will be.

Case 1:
I want the output to go high at the rising edge of the input, output stays high as long as the input is high but output will be pulled down after 500ms even if the input is high.

Case 2:
Output should go low if the input is less the 500ms, i.e. if the Input is of 300ms the output will also be of 300ms.

It can be easily done with micro-controller but i want some transistor or 555 solution if it is possible.


texts:
So, let's say I'm composing a schematic for a circuit I'm designing in KiCad, and... done.

I now have to to choose a footprint for my components.  How does one identify the appropriate footprint for a given component?  I open up CvPCB to an utterly daunting array of possible footprints, none of which seem to be referenced anywhere else in creation- google knows nothing of the footprint "names" seen in KiCad (that I can tell.)

I need the dimensions of a standard DIP pin - I have a component that can fit in this for example (yes, it wil tolerate heat :P)

I am perfectly happy to create my own parts with my handy dandy digital caliper!  It'd just be nice if that massive library that comes with KiCad can actually do something.


texts: Relationship between frequency and power

texts: I'm an electrical apprentice, just studying electrotechnology. I know this doesn't really have anything to do with my trade and that I don't need to understand, but I'm curious as to how a change in frequency will affect power, or if it affects power at all, or if I'm on the wrong track completely. What does a change in frequency do to current, etc.?


texts: In a gps receiver, how is the delay of the signal in the antenna lead allowed for?

texts: In a gps receiver there is an inevitable time delay in the signal travelling in the antenna lead to the circuitry of the receiver.  In a typical 5 metre lead the delay is about 15 nanoseconds, which, added on to the time for the signal to travel from the satellite to the antenna,  would mean a serious inaccuracy if it was not compensated for. How is this compensation achieved?


texts: I2C multiplexer channel selection and pull up resistors

texts:
I need to communicate with 3 batteries through SMBus. I managed to communicate each of them separately one by one. However, I need to communicate with 3 of them, for that I decided to use multiplexer. (These are same kind of batteries so their addresses are same.) The multiplexer I chose is  TCA9546A. TCA9546A

This is the schematic of it, from its datasheet.

I have two questions:

First one is related to pull up resistor values. I used 20 k resistors as pull ups while I was testing SMBus connection one by one and these 20 k resistors worked. But I know 20 k is too much for I2C so I am planning to use 2 k for I2C side and 20 K for SMBus side. I am planning to use 2 k pull up resistors between master MCU and multiplexer and 20 k resistors betweens 3 slave batteries and multiplexer. Would it work or do I need to use 20 k resistors for everywhere or any other option?
My second question is related to channel selection. I have read the datasheet but I could not get an answer. I thought I would use A0, A1 and A2 pins to select channel. (i.e. when A0=1, A1=0, A2=0, choose first slave etc.) But in the schematic they grounded these pins... It seems like I need to send I2C data in order to choose channel. In datasheet there is this information:

So it confused me a lot. How can I choose related channel through it? If I need to choose channel one for example I want to get SOC information from the first battery, in normal case I send address of the smart battery (0x16) then I send command code (0x0D) then I wait for reception. But with this multiplexer how will I do that? Do I use 0x01 as the address register? Then how will it understand the slave address (0x16) by itself. Can someone please clarify it.. Thanks beforehand.


texts: When is the use of internal signals required in VDHL processes?

texts:
Cheers. I am trying to create a toggle D flip flop in VHDL.
My try was :
entity DFFwTOGGLE is
    port(
    D,CLK: in std_logic;
    Q: out std_logic;
    );
end DFFwTOGGLE;

architecture behav of DFFwTOGGLE is
begin
    process(CLK)
begin
    if (CLK = '1' and CLK'event) then
        Q <= not Q;
    end if;
end process;
end behav;

some code I found online however uses internal signals inside the architecture, and then sets the $$Q <= Q IN$$ after the process. Why am I mistaken? More generally, when should I use internal signals? Thanks :)


texts:
What exactly is modulo addressing? I think here is a useful source but I can't understand what it is exactly about. From my understanding it implements a circular buffer.
Is it that? Why is that so important/special that it is a feature of a DSP?


texts: overvoltage protection on TI's reference design

texts: I'm following TI's reference design (PMP11612) for a 5V 2A AC-DC adapter and was wondering if I would need to add overvoltage protection like a zener diode or a TVS diode on the input to this circuit? This design is to used in the US so the mains voltage will be 110VAC.


texts: Designing a circuit that opens when less than 12 volts are applied and closes when more than 12 are applied

texts: I'm looking to build a circuit where current only flows when there is a potential difference across the entire circuit of more than 12 volts (+- 0.1 V). I also need there to be only a small amount of resistance across the part of the circuit that controls whether current will flow, in order to prevent overheating. I'm not sure what I should use to control this; I was thinking of using a zener diode, but cannot find any with a forward voltage above 7V. I'm thinking that there might be some other type of semiconductor I could use, but I'm not sure what it would be. Perhaps I could use a zener diode but put it in reverse orientation rather than forward? I'm not sure how much resistance that would add however. What would you guys recommend using?


texts:
More specifically this RF transmitter which has an incorporated led driver: http://www.mouser.com/ds/2/368/Si4012-35123.pdf

It specifies 4 levels of current on the LED output pin but nothing on voltage overhead. This IC is going to be powered from a 3.3V rail. Will a 1.6-1.8 forward Voltage LED be OK to tie directly to the LED output pin as shown in their diagram ?

  5.2.3. PROPERTY: LED_INTENSITY Purpose: LED current drive strength  Property: 0x11  Default: 0x00  Fields: LedIntensity [1:0]—LED
  intensity  00: LED off   01: 0.37 mA   10: 0.60 mA   11: 0.97 mA.


texts: Need a definition for the term "FPGA image"

texts: I can't seem to find a definition for the term "FPGA image". I think it is just another term for an FPGA configuration that would be stored in say a SPI flash memory chip but I'm not sure.


texts:
I’m a bit confused about capacitors. I understand they store energy in a field by accumulating opposite charges on the different plates. So a 1 farad capacitor will store 1 coulomb of charge if subjected to 1 volt if I understand the math right.

1 coulomb is also 1 amp-second, so this capacitor can supply 1 amp of current for 1 second.

Now what I don’t understand is where voltage comes into this. Can this theoretical capacitor only run 1V loads? Why? Wouldn’t a .5 farad capacitor subjected to 2V also store 1 coulomb of charge? What would be the difference between the charge stored in these two capacitors?


texts:
We have current to voltage converter opamp which has below schematic. Below is the formula to find TP1 Voltage :

Vout (TP1) = I1  x R2 or R1 (depend on the switch2 and not calculating the C1)

the question that I have is when the switch1 is open and nothing is connected to opamp V+ should Tp1 Voltage be zero doesn't matter what is the gain resistor(SW2), and if I am correct why I am not getting this in a real scenario.

I think it is because of the noise or rail power but not sure.I am using TP1 (after some other amplifier) for my 4-20mA output calculation.

simulate this circuit – Schematic created using CircuitLab


texts:
Is there any way to use a single 555 chip which could be switched with a two-state switch between monostable mode (one-shot pulse of a certain width) and astable (continuous pulses of a certain width)?

Here's how I'd like it to work:
I have a two-state switch that i could set into one of the two modes of operation: astable and monostable.

If it is in the astable mode, it generates clock pulses of a certain width automatically until I switch it to a different mode.
If it is in the monostable mode, it waits for me to push an additional push-button called "pulse", which will generate just one clock pulse of a certain width and then return to the "wait for another push" state. In this state, I would have to release the "pulse" push-button first, and then push it once more to generate another clock pulse (to avoid generating multiple pulses at once when I push the "pulse" button for too long or if it bounces).

Is this possible to implement with just a single 555 chip?

The usual implementation schematics I found are only one or the other (either astable or bistable), but I couldn't found any schematic which could allow me to switch between those two modes of a single chip with a switch.


texts: What does a TL062 Op-Amp with output grounded and both inputs connected together with voltage divider mean?

texts:
So I'm studying Kilovoltmeters and subsequently using ADC's with resistor arrays and dividers from high voltage power supplies of all varieties.
I've got a good idea as to what they are and how they work, especially in use for SMPSs. However, in my researching I found this weird texas instruments dual-jfet-amp TL062 configuration with amp A being a buffer followed by the other, weirder amp, amp B; this is the main issue here as is described in the title. The power supply is an SMPS with a long chain of Cockcroft-Walton multipliers.  The link to the pdf is under the image provided.
The inverting input of B is a 1/2 voltage divider with 100k resistors, and the non inverting input is connected via R2 of the divider and also trails off to an Arduino ADC pin.
I know Op-Amp inputs always want to stay the same if the output is used in a negative-feedback configuration, thus virtual ground, but none of that beautiful op-amp action is seen at amp B :(
I'm thinking the second amp is bogus as it's totally shorted to ground and bypassed straight to the ADC; could potentially release some really nice magic smoke. Inputs would be fine, though!
Pic:

https://wiki.jlab.org/cuawiki/images/d/d9/CW-Base_Jan2016_v2.pdf
Any feedback helps!


texts:
Have a an array of type std_logic_vector which holds some status flags which I have to combine(OR) into one single flag of type std_logic.

Is there a more elegant and effective way than doing it by hand

flag <= x(0)(1) OR x(1)(1) OR x(2)(1) OR x(3)(1) OR x(4)(1) OR x(5)(1) OR
        x(6)(1) OR x(7)(1) OR x(8)(1) OR x(9)(1) OR x(10)(1) OR x(11)(1) OR
        x(12)(1) OR x(13)(1) OR x(14)(1);

Can this be achieved using some kind of generate statement?


texts: How can I build a charger for this RC helicopter?

texts:
I have this remote controlled helicopter: http://www.clasohlson.com/se/Radiostyrd-helikopter/31-8071

Currently it is charged by connecting the remote control. However, since the RC runs on batteries, I am thinking it would be nice to charge the helicopter with a battery charger or similar.

I am a complete beginner, and am now looking for how to understand how I can solve this problem. How do I find out what I need? Can I use for example an iPhone charger or anything simliar that many homes has?


texts:
The problem is that I have a Raycool 1000W Carbon Blue electric scooter that started to fail. I checked the battery first. The battery is composed by three 12v 12ah lead acid batteries. (the one in the picture)

I checked the voltage and the 3 in series had 40V. First question: Are they overcharged?

Then I checked the charger voltage.
It gives 48V. Is this normal if it's a 36V charger?
Also the end of the charger is a xlr 3-pin. One of them is totally disconnected, is this normal?

I would like to know if I have to replace the batteries or the charger.
Thanks and sorry for my bad explanation.


texts:
I want to ask some questions:

Is it true that having a large ground plane may help reduce noise? How?
I want to design a GPS receiver and from the design guideline, under the module they put a ground plane which is terminated by lots of vias, what are the use of these vias?


texts: Microcontroller information transfer to Android application

texts:
I wanted to do a project on bus tracking (GPS) through an Android application, therefore in order to do so: I need to install GPS module in bus along with microcontroller so that GPS fetches the bus location and sends it to micro controller.

We are also building an Android app so that anyone can access the bus location. How do I send information to an Android app from the microcontroller?

I heard about Bluetooth but it's irrelevant in this discussion.


texts:
Is there an induced-EMF from two wires being close to each other (d = 1mm)? I'm assuming since each wire has its own magnetic field. Only in the beginning when current starts to flow and then stabilizes?

A diagram:


texts: How to tell how much power I can pull from a DC power supply?

texts:
I have an old TV with a power supply combined with an inverter for CCFL lamps and I'd like to convert it to use LED backlight with a 12v DC LED driver.
Now, inspecting the board, I've found where to pull 12v from for the external driver, but what I'd like to know beforehand is if the PSU part can handle the extra 3/4 amps@12v and no specs show up on Google if I look up the PSU model, all I've got is a schematic of a similar circuit (how similar? afaik they are all used as PSU + inverter for the same line of TVs) and can identify a few key components that afaik are used in PSUs like the transformer, rectifier, caps for stabilizing the output voltage etc. but still can't conclude anything useful (electronics course in uni starts next semester)
Here's the schematic I found:

PCB as it looks like IRL:

Schematic for the PSU part:

Schematic for the inverter part (will probably cut the paths to the PSU part when I'll mount the LED driver):

Thanks in advance!


texts: What does the "Q" in "Clock-to-Q delay" stand for?

texts:
Possible Duplicate:
  Why is the output of stateful elements often named Q?

A register has D (data) as input and Q as output.
What does the Q stand for? I'm having a hard time searching for it.


texts:
According to the datasheet, the ATMega168 can only execute self-programming instructions when running code from the bootloader block.

Once the bootloader is complete and the application starts, can the application then jump back into a subroutine in the bootloader block and have it write to the flash?

Or, is it the case that once the program leaves the boot block it's not allowed to self-program again until after a reset?


texts: Can I turn on a 12V relay with 5V supply, just by changing a resistor?

texts:
I have been trying to run a W1209 module with 5V instead of 12 volts. My application is heating a small component to 70 degrees of Celsius, mostly using a power bank or a mobile charger (Hence the 5V). The original w1209 runs at 12V DC. After posting my initial question about running the module at 5V here, I did some experiments and found that module runs happily at 5V, except for turning on the 12V relay. Now, I am thinking to just decrease the resistor R7 value, in the schematic to lower value, so that it can turn on 12V replay with 5V input. I am not sure of this idea, please suggest me if this is possible.
Can W1209 be run with 5V DC only

EDIT1:
Thanks for your answers, I understood that only option is changing the realy to 5V relay. So, I am going to buy the following 5V relay. Please let me know if this one looks alright.
https://ie.rs-online.com/web/p/non-latching-relays/6839188/
Original relay is 12V,  T78-S-HS

EDIT2:
I ordered the 5V relay, but it hasn't come yet. In the meantime, I tried to use a N-channel MOSFET. But as it turns out my MOSFET is not turning on at 5V operating voltage as the voltage after Q1 is below 2V. I had to increase my input voltage to atleast 6.2V, so that after Q1 it will be 2.8V. Moreover, this voltage at Q1 is high when the relay was usually in open position and becomes low when the relay was closed. So, when I replaced the relay with N-channel MOSFET, MOSFET is switching on when it is supposed to switch off and vice versa. I think I should have replaced the relay with a P-channel MOSFET instead of N-channel MOSFET. I am updating here my progress, so that it might be useful for others. I will update again after trying with a 5V relay. I added my new schematic figure to elaborate on how I replaced relay with a N-Channel MOSFET. R value is 10 kilo ohms.

EDIT3:
Following @Bruce's suggestion in the comments below, I connected the 'pull up' resistor to 5V and then it start to work without any issue with MOSFET.


texts: PCB component-less debug port suggestions

texts:
I need around 8 connections in a PCB I'm designing for debug and on board programming. Originally I had this debug connection's footprint as a simple single in line with headers: http://www.jameco.com/Jameco/Products/ProdImag/164822.jpg

This port is going to be used just one time, so is a huge waste of material, space and money if I decide to mass produce this PCB. I was looking for some commercial solutions to get inspire and I found this: http://www.telexsus.com/products/tag-connect/tc2050-idc-nl

The idea is very smart, no components on the PCB, just an SMD footprint and 3 holes to keep align the cable contacts to the pcb. I will like to know if there are other component less solutions, specially DIY.


texts: At what test frequency should electrolytic capacitors be measured?

texts:
At different frequencies  electrolytic capacitors have different capacitance. Suppose it is 50 uF 16V capacitor (type K50-16), then the measurement results are (using russian E7-14 RCL tester):

1) At 100 Hz - 57,31 uF
2) At 1 KHz - 38,20 uF
3) At 10 KHz - 3,56 uF

So my question is - which frequency the manufacturer had in mind?


texts: Abuse TS339 comparator channel as a voltage multiplier

texts:
I have multiple free channels of a TS339 amplifier remaining and would like to use one of them to multiply voltages like this:

simulate this circuit – Schematic created using CircuitLab

Now it's a common rule that you should never use OpAmps as comparators or vice-versa, but I'm wondering whether there's any fundamental issues that prevent me from doing so here.

I need a bandwidth of 400 kHz and a gain of 5 (as visible in the circuit).

The comparator's output is open-drain and it's CMOS-based, but I assume it can operate in its linear region just as well?

The output load will be less than 100kOhms, with no capacitive load.


texts: If I understood correctly, current BGA components contain solder balls under the package. Do I still need additional solder paste to put on the board, or the amount of solder on the component contacts is sufficient?


texts: Where does inductor current go when the RL circuit switch opens?

texts:
I'm struggling to wrap my head around a 'should-be-simple' problem involving an RL circuit. Referring to the image I've pasted below, what happens if we were to remove switch 1, and instead created a scenario where switch 2 simply opens? Where would the current go in the inductor?

I know that the current in an inductor can't instantaneously change, however, if switch 2 opens, it is now located on an abandoned branch thus can't allow current to flow...

How is the energy in the inductor is released?


texts: Materials required to convert NiMH rechargeable 24V/6Ah circuit (20 C-cell) to Li-Ion rechargeable circuit

texts:
Below is a picture of a battery shell for a NiMH circuit for a power assist wheelchair battery.  I'm taking a guess that each of the 20 batteries is 1.2V because the entire circuit is 24V.  These are rechargeable.

I'd like to convert this circuit to the same voltage (24V) and same capacity (3Ah).

First, is this possible given the space you see in this wheelchair battery shell, and the circuit board in the pictures?

Second, what are the material requirements to be able to convert this circuit from NiMH to Li-Ion and the type of charger as well?  What materials will I need to solder/weld the materials together, etc.. for the actual labor?  I'm an electrical novice, so please ask me more questions (as comments) and I'll do my best to answer.

Note: right click image and open in a new window to make it larger!


texts: In a Class-C power amplifier, what does the resistor in the base do?

texts: Look at the picture, which shows a Class C power amplifier (source). What is the role of the resistance in the base of the transistor, and what happens if it's removed?


texts: Plastic Plugs in Surge Protectors or UPS

texts:
Would plugging 4 out of 7 outlets in a surge protector or UPS with plastic “safety plugs” to keep out dust/dirt harm the product in any way?

I know that plastic is an insulator and it might affect the UPS or surge protectors amount of power it can supply by a slight margin?

Sorry for my ignorance but I am not sure how plugs would affect the product on a “slight” level and am just generally curious.


texts: Logical Design Operation, A Simple Questions?

texts:
I'm so sorry if I ask my first question that so simple. My filed is Math and Computer science.  I self-study Digital Design.

  My challenge is how we can find the operation of the two following Diagram
  ?


texts: What is this schematic symbol? A transformer?

texts: I found this schematic symbol I've never seen before. I think it's some type of transformer? Please let me know what it is.


texts: Relation between torque angle, power angle and power factor

texts:
Considering a synchronous generator, is there a relation between power angle (angle between V terminal and V induced), torque angle (difference between rotor flux and stator flux) and power factor(current and voltage phase)? A phase diagram of synchronous generator with field voltage, terminal voltage and current is useful to understand relation between power angle and power factor, but nowhere I see torque angle in picture.
My intention is to understand the relation between magnetic and electrical phasors. For example, I think stator current and flux will be on same phase and v terminal and rotor flux will be 90 degree phase shifted. Also, can someone share a link to phasor diagram with magnetic variables.


texts: I have a BLDC motor rated at 72V 1500W. I am working on an application that requires me to perform certain computations using the RMS current but I understand that I can only get the rated current from the values given. Is there a way to compute the RMS current from just the rated voltage and rated power values given?


texts: How can I connect two audio channels (L+ L- and R+ R-) to a jack (L, R, GND)?

texts:
I am working on a "device" based on a CSR8645 Bluetooth Receiver module from eBay. .
My current issue is the fact that each audio channel has its own ground, and if I connect both grounds together to the jack, the sound coming out is distorted. Granted, this may be an imperfect connection on my part or the PCB is faulty.
This gentleman here also has a similar issue. Granted he's getting mono output and wants to output to speakers (with each speaker having its own ground).
Looking at his post, maybe my board is using the same bridge amplifier technique. If that's the case, how can I properly drive a pair of headphones (Left, Right, Ground) with my module which has L+, L-, R+, R-.
Also a bit off topic, I would like to connect the microphone output as well but that's not the main issue and purpose of this question (granted if I want to connect my microphone which also has its own ground...


texts: Change of variable from t to \$\tau\$ during convolution

texts:
I am not able to understand that in the standard convolution formula how we can change the variable from t to \$\tau\$.

$$\int{x(\tau)\cdot h(t-\tau)d\tau }$$

Isn't this incorrect mathematically?


texts: Power dissipation of a current limiting resistor (connected to an input pin of uC.)

texts:
Below I have attached a circuit which divides the voltage and gives the output to an input pin of a microcontroller.

Input voltage = 24V

The resistor R0012 is for current limiting.  The Zener diode breakdown voltage is 5.1V.

The microcontroller which I am using is - Microcontroller Datasheet

I could not see an GPIO input pin internal architecture of diagram inside the microcontroller datasheet.

I tried to simulate this portion of the circuit with the MCU end floating. I found that the voltage before R0012 is 2.9486561V and after R0012 is 2.9486144V. The current through it was 2.953uA.
I couldn't understand how this current is obtained (even though I left the other end of the diode floating - nothing connected at the MCU end.)

My objective :

I want to calculate the maximum power dissipation of the R0012 current limiting resistor. I know that it will not dissipate a huge amount. Just want to understand.

My questions:

The microcontroller datasheet attached mentions a GPIO sink current of +3mA max. So, what would be the current flowing into the microcontroller pin in my case and what would be the voltage detected at the MCU pin?
How to go about calculating the power dissipation of the resistor?
How did my simulation show a current of 2.953uA?


texts: I have this incomplete circuit. I want to know if there is any other way ,except inverting each decoder's output or making changes in any other IC, to make the desired output be H and the others L?


texts:
A diode has an exponential I-V curve. To a first approximation, it will pass whatever amount of current is required to keep the voltage across it constant.

Is there a passive component that will (approximately) drop any amount of voltage to maintain a constant current, possibly with a logarithmic I-V curve?


texts:
I have been delving deep into digital logic and am trying to understand some memory architecture basics. I have started looking at data sheets to get a grasp on some real-world components and noticed something that I couldn’t find a clear explanation on.

In a data sheet for a 256x8-bit RAM module interfaced by I2C. There is all the things I would expect from an I2C device, however, there are also 3 pins for "Hardware Addressing". The data sheet explains:

  "Three address pins, A0, A1 and A2 are
  used to define the hardware address, allowing the use of
  up to 8 devices connected to the bus without additional
  hardware."

I obviously understand that this is for adding multiple devices, but I don't understand for what purpose? Not to mention if this is to signify an individual hardware device how much of a I2C pain it would be to sync. Maybe not?

I have included the data sheet and any clarity would be great.

DATASHEET (I know this is an old device, but I'm in it for the education)


texts:
I wanted to measure a LVDS signal across the termination resistor with my oscilloscope. I tried to measure it with DC coupling and AC coupling. Using the AC coupling option led to a short circuit I saw some sparks.
Why did the AC coupling option led to a short circuit?


texts:
I am in the "a little knowledge is a dangerous thing" zone, but at least I am aware of it.

If I take a working (not plugged in) transformer for Halogen lights (240 V mains down to 12 V) and measure the continuity of the 12V side, my multimeter says it is continuous.

But if I measure the continuity of the 240 VAC side, I get that it is not. Huh?

If a transformer is basically two coils inside each other, right? Why isn't there continuity on the mains side?

Here are some more details:

Transformer #1:

ATCO Speedy TED-070 Electronic Safety Isolating Transformer

 .

Transformer #2:

OSRAM ET-REDBACK Electronic Transformer Like this one. Same results.


texts: RN 171 (RN-XV Wifly) scan and connect to another IBSS Ad-Hoc Network

texts:
My setup is as follows:

A Raspberry Pi + Realtek WiFi Dongle. It is configured as an IBSS Ad-Hoc Network (SSID = "pi-adhoc"). This works so far. I can find this network and connect to it from my laptop, even create TCP Sessions and send/receive data, etc..
A RN-XV Wifly Module connected to a STM32F via UART.

What I want to do is, that I want the Wifly to connect to the Pi's Ad-Hoc Network. The first step was to set PIN9 of the module to "high" i.o. to have the Module itself create an Ad-Hoc network. I connected and opened a Telnet connection to configure the module. I then triggered the Wifly's scan with the "scan"-command. The Problem is, that my "pi-adhoc" network is not found by the Wifly while all other devices (Laptop, Smartphone, ...) do find it.

Maybe someone had the same issue and can help me with this.

Edit:
For those stumbling upon this question later on. Found out that firmware 2.32 does not support adhoc mode. Updated to version 2.36 and successfully scanned my "pi-adhoc" network.


texts:
I want to interface an ASIC with a SAR ADC, e.g. LTC2323-14 (5MHz, 14 bit). The timing diagram looks as follows:

I would like to generate the control signals (i.e. CNV and SCK) with my ASIC, based from a master clock (e.g. 100 MHz).

The datasheet states:

tCNVH >= 25ns
tSCKL >= 4ns, tSCKH >= 4ns, tSCK >= 9.4ns
tCONV >= 171.5ns
tDCNVSCKL >= 9.5ns
tDSCKLCNVH >= 19.1ns

I am confused by this diagram: Do I need to turn off SCK while CNV is high? Do I even need to make sure that the first pulse does not appear after tDCNVSCKL after CNV goes down? This would make my clock generation extremely hard.

Or can I just leave on SCK all the time and the timing spec just means that I can expect B14 not before tDCNVSCKL?

In this case, I would just use a, say, 100 MHz clock as SCK input and derive CNV from this clock; e.g. creating a 3 period pulse (30ns) used as CNV.

Also, the DS states: "The typical pulse width of the CNV signal is 30ns at 5Msps conr rate" and "A 105 MHz external clock must be applied at the SCK pin to achieve 5Msps throughput".

I do not understand how exactly 105 MHz are obtained:

For 105 MHz, tSCK=9.524ns.

CNV takes at least 3 cycles to satisfy >25ns
The 15 data bits require 142.85714ns
tDCNVSCKL requires at least 1 cycle
tDSCKLCNVH  requires at least 3 cycles.

Summing this up makes tTHROUGHPUT of 3+15+1+3=22 cycles or 105M/22=4.773 MHz < 5 MHz.

For the data this would be 15 cycles, tDCNVSCKL is one cycle, tDSCKLCNVH is three cycles.


texts: Drive 24V Lamps. Will this circuit work?

texts:
I made a circuit to read the data from a ultrasonic sensor and drive two 24V lamps. Will this circuit work? The relay ALREADY has a flyback diode.

Am I missing something or it's all good?


texts: What kind of oscillator circuit technology is used for 5G technology?

texts: In particular, are 5G oscillators found in cellphones using some kind of SMT/fabricated Gunn diode or Impatt diode(on a chip)? The frequency bands(K band) are beyond the range of crystal oscillators. But what other kinds of technology is used to generate oscillators this high in frequency using solid state?


texts: How can i calculate the time that is elapsed between two sensors in vhdl?

texts: I am new to digital design and having trouble in calculating the time between two sensors that gives digital output? How can i approach to this problem? I thought of writing the outputs of digital sensors in the process statement and when the first sensor gives 1 it starts the time and when the second sensor gives 1 it stops the time. However,since the sensor i am using gives 0 right after a moving object moves infront of it i cannot store the time. Does anyone has suggestions about it? Thank you.


texts: How to calculate line capacitance for I2C (100kHz) communication

texts:
I want to communicate between ATmega328P chips over I2C.
I have found this bus extender which allows a max capacitance of 3000pF.

I found this data-wire, which has a mutual line capacitance of 25pf/ft @ 1kHz.

But I2C communication runs at 100kHz (by default). (How) can I calculate the line capacitance of this type of wire at 100kHz? Or in other words what is the maximum length I can span with this type of wire between two extenders?


texts: Connected diode transistor collector current

texts:
The current source in the following picture is an ideal current source:

It is asked to calculate the Collector current based on I1 and ß (Beta).

What that is weird to me is that I think Ic must be zero because of the short circuit connection between Base and Collector (Which means Voltage of BC diode is 0 and so the diode is off). So the question is that:

Why we have a current in the BC diode greater than 0? (And how can I calculate this current?)

Can you please add the small signal model of the circuit too?


texts:
Excess Carrier Generation and Recombination :

The net rate of change in electron concentration is given by:

\$ \frac{dn(t)}{dt}=\$ Thermal generaton rate-Recombination Rate

\$ \frac{dn(t)}{dt}=\alpha _r[n_i^2-n(t)p(t)] \$

How is Thermal generation rate given by \$ \alpha _rn_i^2 \$ and Recombination Rate  given by \$ \alpha _r n(t)p(t) \$ ?


texts:
Suppose I have 3 signals generated by NMOS logic. Each of those signals has an associated enable pin that when driven high will result in the value of the signal appearing on the output (I should note that signals A,B,C originate in different areas of the circuit so using an OR gate to combine the enable signals would be inconvenient). I came up with a way I think should work, its circuit diagram shown below.

EDIT: An elaboration on the application I would want to use this in:
I have a series of registers, and each one has an enable pin. When a registers enable pin is high I want the value stored in the corresponding register to appear on a bus

In CMOS logic something similar could be accomplished by setting the pins disabled to high impedance and having only the enabled pin driving the output line (this would require only one enable line is high at a time- which is something that is true anyways).

My questions is are there any drawbacks to the method I have on the circuit diagram? I am aware that the speed the coquet can run on is limited by the time the output line can rise, and that the circuit will consume more power than the CMOS version.

Im particularly interested in the amount of signals this could work with and anything else I should know about before implementing this on a PCB.


texts: Model running slower than RTL in SystemVerilog

texts:
I'm testing an RTL implementation of a certain block from a 3rd party company in SystemVerilog using Questa. The block is fairly large and my block which acts as a wrapper around it is also large. The regression suite took around 20 hours to complete. I have access to only one license and with this much time, nightly regressions are not feasible.
So I thought about making a simple model in SystemVerilog. I was able to extract the functionality based on the data-sheet provided. It was simple enough.
The I/O interfaces were AXI4-streaming and it had one AXI4-mm DRAM interface. I used associative arrays within the model to capture any previous data(i had a unique ID to do so). Any processing was done by utilizing a golden reference model (C-function provided by the company) via the dpi.
Now the regression is taking over 30 hours to complete. Clearly, I've done something very wrong and I have no idea where to begin.
Any thoughts will be appreciated.


texts: How to find Thevenin equivalent of this circuit? Dependent current source

texts:
How to find the Thevenin equivalent circuit as seen from terminal a-b.
I found out the value of Zth with ease but I'm not able to find the value of Vth.
I tried using both nodal and mesh analysis and I got an answer of 57.8378 - 2.972j V for Vth, but it is wrong.
KVL equation (4-2j)I1 + (8+4j)I2 + Vth=0 (Considering current flowing in lower loop as I1 and upper loop as I2).
KCL at node 2: -V0/(8+4j) = 5 + 0.2V0.
I don't know how to get the correct answer.


texts: Implement a circuit for (a+b+c)x+(a+b+c)'x' using only OR and XNOR gates

texts: I know XNOR is AB + A'B' so I thought the equation somehow expands to ax+bx+cx+a'x'+b'x'+c'x', but that doesn't seem right because (a+b+c)' is not the same as (a'+b'+c').


texts: Surge protector outlet with altered grounding potential

texts:
I realized that I have a voltage difference of 5 to 80 V AC (orange in Fig. 1) between the protective conductors (grounding cables, "PE-Leiter", yellow-green contacts in drawing) before vs. after a surge protection device (Fig. 1: red box; photo in Fig. 2). Always measured the "permanent" outlet of the surge protection device (green circle in Fig. 2).

The range of 5-80 V results from several measurements (40, 68, 75, 5, 30, 80 V) after dis- and re-connecting the SPD to the wall socket, without effect of connecting a tablet charger or nothing at all to surge protector outlets).

Questions:
Is this difference of 5-80 V AC normal? Why is this difference? Am I getting sth. wrong? Possibly result of phase shift b/o "non-Ohmic" elements in surge protector (might skew Null position, but should not affect grounds, right)?? (sorry for my ignorance if this is possible at all)

Additional information: Renting apartment house, 230V AC, TN-C-S network, i.e. Null (blue) and ground wires (yellow/green) are separated in the whole apartment. Load in the whole apartment is currently moderate: a normal household fridge in kitchen, PC + monitor, LED ceiling lamp (all before surge protector), and nothing or tablet charger plugged into surge protector.

EDIT: As suggested by Justme (thanks!), I added measurement of resistances (see updated drawing in Fig. 1), suggesting that the conncetion between the SPD plug and SPD outlet grounds is fine, but not the wall socket ground of spcifically the one wall socket I had chosen for the SPD (Fig. 3)!

Fig. 1: delta-U of 5-80 V difference after surge protector. Dotted lines indicate measurements with multimeter (Fig. 2): Grey, as expected only mV range (esp. between heating tubes and AC ground); orange, unexpectedly high AC voltage difference. The two ground wire contacts in the sockets are in standard position (German "Schuko-Steckdose") and connected to each other. Drawing to upper or lower one only for graphical reasons, no technical meaning. Edit: purple, resistance measurements.

Fig. 2: photo of surge protector and used voltmeter. Green circle: clamp used for measurement of ground potential after SPD.

Fig. 3: Photo of wall socket outlet where the previous tenant (hope it was not a professional painter) had obviously been very generous with wall paint, adding some (imperfect) isolation to the ground contacts (red circles). Leaving the ground contacts functional would have been more important than all the semi-functional child-proof plug-locks (residual glue in the socket). This is not what I expected and inspected when I moved in in a hurry, new job, lots of things to do. The socket is behind a cabinet, making it hard to see and inspect... Lesson learned. I am glad no accident happened! Probably each dis-/reconnect cycle did or did not scratch some paint resulting in the variable (delta 5-80 V), but still bad connection.


texts:
Can we use 60 Hz induction motor in 50 Hz Current Supply,
What are the possible failures can happen if we use the motor continuously under this circumstances.


texts: Understanding the biasing of a transistor with negative feedback

texts:
I am trying to understand the following circuit.
However, I don't understand this step in the accompanying explanation:
"A transistor with a large gain will cause a large voltage drop over the collector resistor. Because of this, the collector voltage and the base current will decline."
I don't 'get' why this chain of reasoning is true. Why does a large gain causes a large voltage drop over the collector resistor? And then, why does this cause the collector voltage and base current to drop?


texts: 2 E-Mosfets connected in series calculations

texts:
So suppose we have two E-MOSFETS connected in series across a 10V supply, and the upper MOSFET has its drain connected to the gate, and the lower one is unbiased. (The input is taken to be the gate of the lower MOSFET and the output is taken to be the drain of the lower MOSFET) The Upper MOSFET has a resistance of 2k ohms, and its gate-source voltage is 10V. The lower MOSFET has a resistance of 150 ohms when input voltage = 3V. What is the output of the circuit when the input is 0V and 3V?

We learned in class how to do calculations with one mosfet but on the sample exam this question was asked. I'm pretty hopeless at this (as I'm a CS student and we are forced to take this module for some reason) and was wondering how to do the question. (The lecturer literally repeats the same question every year)


texts: Why does my oscilloscope work even without the ground connected to the circuit?

texts:
I am using an oscillator to produce a sinusoidal signal of around 100kHz. I am using a Hantek PC oscilloscope for testing. I observed that even though I disconnect the oscilloscope ground from my circuit, the signal remains the same. How is that possible?

Any idea?


texts: Voltage reference output impedance calculation

texts:
I'm using AD7190 to sample 4ch single-ended signal. The datasheet suggests ADR431 or ADR421 as voltage reference for AD7190. However, an article on Analog Dialogue gives a way to calculate whether an additional output buffer is needed for voltage reference.
The article gives an example:

So, I did calculation myself for ADR435 and AD7190.
The output impedance of ADR435 is calculated in the article above.
The AD7190 is 24bit ADC and the Iref is 7uA/V, which gives its Ro_max=(5V/2^25)/(7uA*5)=0.00425 Ohm.
The Ro_max(AD7190) < Ro(ADR435).
Is that means a output buffer is needed or my calculation is wrong?
Thanks.
The link of the article is down below.
https://www.analog.com/en/analog-dialogue/articles/precision-successive-approximation-adcs.html


texts: DC residual current detection 24 volt DC

texts:
I am trying to make a DC residual circuit breaker( same as AC 10 mA RCCB) for 24 volt DC load. How can I sense and compare currents in positive and negative terminals and powering circuit off, a difference or leakage observed.
I tried with voltage divider as one resistance in series with +Vcc, the other in series with Gnd  and load connected beween two resistors to sense any drop in leakage curent.I am trying to sense leakage current when human touches in 24 volt DC circuit with working total circuit/ load current of 40 mA. Unfortunately above my approach not working.


texts: Building accessories for a Powerstar LiFe battery

texts: I have a Powerstar LiFE battery with 4 pin XLR outputs. The outputs are listed as being 8 amp outputs and 3.5 amp outputs. Does this mean that they will output up to 8 and 3.5 amps or does this mean that they are "presenting" 8 and 3.5 amps; that is, is there any way to know if current is always present at the output or if current is regulated based on load?


texts: An emitter follower to isolate MCU from load?

texts:
I am trying to drive an LED strip (10 LEDs) from the output of an ESP8266 GPIO pin. I measured the short circuit current from the GPIO and got around 40 mA. My question: Is it recommended to include an emitter follower stage to isolate my ESP8266 and my load (LED strip)? I don't want my load to draw a large current from the MCU pin which could alter the logic level.

A crude circuit is shown below (component values are not as per calculation)

simulate this circuit – Schematic created using CircuitLab


texts: How to take a nixie power supply and make a low power frequency modulated signal

texts:
The project I am working on requires a low input voltage stepped up to a high voltage at a certain frequency and PWM with low power.
I found a nixie power supply circuit that can supply 170V at 20mA with a 5V input found here.  I then need to take this output and convert it into a signal of 170V with a frequency of 400Hz at a duty cycle of 25% and power of 800uW.
I need to know if this is possible and if it is what I need to do to accomplish this?
I was thinking of using a 555 timer in astable mode to drive a FET but I can only get down to 50% PWM using this method. Plus I am not sure how to get the power to my desired level on the output after that.


texts: Can someone explain the following flip-flop circuit?

texts:
I'm having trouble understand what's going on in this circuit.  The question asks "what is the value of Q if \$\bar{R} = 1\$ and \$\bar{S} = 0\$" (as shown).

In this case, how can I determine what Q looks like?  I realize that this question may require knowledge from the one above, which is why I asked it first.  Any information about where to go would be great.


texts: What is the best way to configure an electric fireworks igniter

texts:
I've seen a bunch of tutorials on creating a fireworks igniter using, a resistor or a piece of copper wire and a 9 - 12 v battery. Basically you the resistance from the small piece of copper or 1 ohm resistor get so hot it triggers a match. The professional ones use nicrome wire. I'm interested in trying this out, and I have an 18V drill battery, alligator clips, and thin piece of copper wire. I measured the resistance of the copper wire at about 1 ohm.

Will closing the circuit for a small amount of time damage the battery?
Can the current from the drill battery melt the copper?
Would another conductor that is not as good a conductor create more heat with less current?


texts: Help understanding the dimensions of the 1N4007-SMD's datasheet

texts:
I'm trying to understand what are the real dimensions of the following diode:
http://www.sycelectronica.com.ar/semiconductores/1N4007-SMD.pdf
For simplicity, here is a screenshot of the relevant part from the PDF:

By looking at the dimensions, one can notice that there is a pair of values for each dimension. For example, the first horizontal length is 4.597 / 3.988.
What is the meaning of those numbers?
Thanks!


texts: GLONASS and GPS satellite usage simultaneously by Positioning Modules

texts:
Can a GPS module use 2 GPS satellites and 2 GLONASS satellites to obtain a fix without using all satellites of the same kind?

I know that we cannot force this to happen but is it theoretically possible for this to happen?


texts: Trickle charging 10NiMh in series with ~1W solar panel

texts:
I have been put onto a project that needs to be powered by a small (1-2W) solar panel trickle charging a battery pack. The product will be located on rooftops. We have reviewed similar products and have found them to be using NiMH batteries so are planning on following suit. I have reviewed many similar posts, particularly the below, but still have some unanswered questions, apologies if I am repeating the questions of others.

Charging 6 NiMH batteries in series via solar
Charging NiMH batteries with 1W solar panel, charge controller needed?

The battery needs to supply power to a 12VDC motor and a 24VDC Actuator (planning on boosting 12V to 24V) but these will only be active for a small amount of time each day so overall energy requirement is quite low.

At this stage we are planning on using 10xAA NiMH 3600mAh in series to get a 12V output. I plan on using a Zener diode between the battery and panel to prevent back discharge at night.

The solar panel will be something like the 12V model at the bottom of this page:
https://www.futurlec.com/Solar_Cell.shtml

I understand that trickle charging NiMH batteries is not ideal, but it seems to be commonly done and NiMH seems like the ideal chemistry for the application.

My questions are:

Is a 12V panel the best choice for trickle charging the 10 batteries in series?
The panel linked outputs a peak of 80mA, 80/3600 = 1/45C, my understanding is that this is well within the safe limits for solar charging of NiMH, is there a benefit in regulating this to a constant current (with LM317 for example)?
Should we be considering including an IC such as the DS2715 to monitor battery level and prevent overcharge, or is this completely unnecessary given the low output of the panel?

Happy to provide any more information that would be useful.

Cheers.


texts: Calculating voltage through unknown resistor

texts:
I'm asked to get the voltage Ix and Vx, as you can see in the image, the voltage is on an unknown resistor, through loop analysis I got that Ix should be equal to 1. by KVL( Kirchhoff's Voltage Law) I had
$$5(Ix-6)+1(Ix)=0$$
although, I'm not quite sure if Ix and the 10A current source interact in this equation. so that is why I'm asking this.

For node analysis, please use this image (I'm not sure about N5 being a node btw)


texts: Can power transformers be used with higher voltages?

texts:
I purchased a Japanese transformer for a project I’m doing. It runs on 100VAC, not 120V, something I overlooked. Doing a quick search, Japan seems to use both 50/60Hz, based on the region.

It’s 30 years old and there’s no information about frequencies on it. I haven’t plugged it into anything yet.

How exactly will it respond to 120V? Here are some possible outcomes I’ve thought of with my limited knowledge.

It will initially work for a few minutes/seconds, then it will get fried and become useless
The output voltages/current will become stronger
Nothing will happen, and then it will get fried and become useless

Here’s a part of the schematic I’m using it for. It’s supposed to output +15V, -15V, and +5V.


texts: Polygon not pouring over net tie pads in Altium

texts:
I am working with net ties in altium to link different ground signals. My net ties seem to work, no drc error, and I can link traces between them and objects of the same net.
If I try to pour a polygon over them however, nothing happens. I even created a component class to have direct connect for my net ties. My polygons are set to pour over all same net objects and it works well for anything else... the only problem is my net tie and I dont know wht is causing this behaviour?

Here you see the net tie, joined to a copper region on its left side (works) but the gnd plane polygon cannot pour over its right pad!
Thank you for your help!


texts:
I have a custom computer with a custom case that I would like to re-purpose the power switch on, but only when the computer is running.

I have a Teensy board (similar to Arduino) inside the case that handles button presses and communicates to the custom application I have via USB.  The problem is, the front panel only has 2 buttons, one is being used for the motherboard power switch, so I only have one available and I need 2.  I don't want to physically add a new button for aesthetic reasons.

At first, I looked into Windows APIs for detecting the power button pressed, but it looks like the only way to do this is with a custom driver, and that's a route I don't want to go down (and I don't have a signing key for an x64 driver anyway).

So what I want to do is be able to use the motherboard power switch (on the front panel) to power on the computer, or wake it from sleep, but when the computer is running, have my Teensy board detect the press.  I've already set in Windows to have the power button do nothing when it's pressed while Windows is running.  I just need to figure out how to connect the Teensy board to the power switch to detect this without screwing with the power switch operation when the computer is off and going to be turned on.

The Teensy input can be configured to be external (where it must have high +5V or low 0V all the time - floating inputs do not work), or configured to have an internal pull up so it is high when floating externally, and low when connected externally.  The Teensy runs off USB +5V power, and I have confirmed that the USB ground and the power switch ground are the same ground.

Alas, searching online, I've had trouble finding specifications for how the power switch works, or even if it is standard amongst different motherboards.  So my question is, is there a way I can hook up to the motherboard power switch pins to still power on the motherboard when it is off (and the Teensy is therefore also off - no power on USB while off), but detect the button press on the Teensy input while it is on?


texts: How to find equivalent resistence of this mixed circuit?

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Find equivalent resistance, the current in R5, Voltage of R2 and power of R10.

Actually, I don't know if my attempt is right. So, you would point out where there are mistakes, pleased.

R10 and R11 are in parallel (I called this R1011), also, R6 and R7 are in parallel (R67). Then R1011 and R12 are in parallel (R101112), then R9 and R101112 are in serie (I called it R9101112). Then R9101112 and R13 are in parallel (R910111213), then R1, R2, and R910111213 are in serie( R12910111213) And so on, Until now my circuit its this:

Then are R5 and R3 in paralell? If this is right I can continue myself. Another question, how to get current in R5 and voltage of R2? Kirchhoff's Rules ?


texts: Power supply of 5V 1A causing erratic behavior of Tower Pro SG90,- what's the reason for this? Also occurs when using the MB102

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I need to power an SG90 servo but am having trouble with erratic behavior when using a phone USB charger of 5V 1A or when trying to use the MB102. The MB102 voltage regulator also overheats within a few seconds.
Is there an explanation for this and a solution? Do I need a voltage regulator?


texts: replacing smd atmega328p on a arduino nano clone

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I accidentally blown up the original chip. :embrassed

I have successfully soldered a new chip on but the MKII programmer won't enter programming mode. but I can clearly see  the characterisic not quite perfect square wave on my scope.

Am guessing it's because the chip hasn't been configured to use the external crystal.  Besides buying a new dev board/ removing the tiny crystal, is there an easy way I can get myself out of this mess?


texts:
Hello!
I have an device which is equivalent circuit is RC as follows in the image I shared:
R is supposed to be 0.5Ω and C supposed to be 30nF, but it can vary a little bit between device to device.
I cannot touch the leg between the capacitor and the resistor!

While I can measure the capacitor value pretty accurate with LCR meter the resistor reading is off...way off

I tried to find way I could get a hold of the resistor magnitude and it came across my mind that if ill add an inductor in series and If I can work at resonance in the range my signal generator works, 30 MHz, then I could find the value of the resistor or atleast I could know the difference between 0.5Ω to 1Ω.
This is the circuit I draw with the values I picked.

Using the signal generator with a steady sine wave, I found out the resonance frequency was more than double that I calculated.
I guess it was because of parasitic capacitance and inductance in the BNCs I used.

But what bothered me more was even though I found the resonance frequency the gain was only 5 times greater then the voltage input.
Moreover at this point I found out I didn't know how to translate the results to find the resistors value.

I solved the circuit for steady state as follows:

Now the only way this have a chance to be a logic value is if L\K-L >0 .
This means that must be k<0.
But as I mentioned earlier the gain in scope was of order of 5 ... k=5.
I tried to put all that data inside the equations (Fres,S=2*pi*F;L,C)
but no matter what I get a negative value for R.

Can you tell me where I am wrong? Because I can't see error in the way I solved the transfer function or in the way I solved the parametric equation.

Also do you guys got any suggestions in how can I measure the resistor? I need a practical idea as I don't have a 30 GHz spectrum analyzer.
I got LCR meter, normal scope, and a signal generator which can generate up 30 MHz.

EDIT:
Only now I noticed I had a mistake in the capacitor value which is 30nF!
I will fix it yet the problem in the equations remains unsolved.
Why I am getting a mathematics error and how can it be explained?
RLC equations is good , and k is suppose to be greater then 1 in resonance so why from the equation it comes that it can only be solved when k is < 1?


texts: Linkwitz-Riley "isolator" equaliser question

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I don't understand one thing about 3 way EQ based on Linkwitz-Riley crossover. We split the signal to 3 bands - low, mid and high. Why is mid band phase inverted? It doesn't make sense to me, but people do it for some fundamental reason.

The most confusing thing is that in LTspice simulation inverting the "mids" phase ruins the frequency response. The response is flat when 3 bands have equal, non inverted phase. The last picture shows the response of 3 bands of circuit which doesn't invert the phase of any band.

More info about inverting here: https://sound-au.com/articles/eq.htm#s9

Thanks for help :)