texts:
I just recycled this motor and I would like to use it to generate and charge at 60 V. It’s rated at 6350 rpm at 95 V. It's a brushed DC motor. It has two poles.

Is it possible to remove the two ferrite magnets and replace with a multiple of neodymium magnets to reduce the rpm?

My theory is 2 poles 95 V, 6350 rpm; 4 poles, 95 V, 3175 rpm; 8 poles, 95 V 1588 rpm; 16 poles 95 V, 794 rpm; ...

Is this actually possible?


texts: Detecting movement of a mechanical ring using optical sensors

texts:
I need help deciding on which sensor to use for my current home project. Basically I'm trying to replicate the Numio Control but at much cheaper cost. If it is successful I will publish the result online open source. But as of right now I am stumped on the rotating part. One of the main problems is, that it will be portable, meaning the sensor should be somewhat resistant against shock impacts. There also is not a lot of space, so the sensor needs to be small (a few mm at most). Also the processor will be a ESP32 with a 600mAh battery, so no crazy calculations are possible. Ideal would also be some sort of interrupt, so my ESP32 can wake up on wheel rotation. Also important to know: The enclosure and all inner workings will be 3D-printed... so nothing crazy mechanical either is possible.

Moving on to the progress I have made...
I began looking on the video senic (the manufacturer of the numio control) provides very carefully, but couldn't find anything worthwhile. There aren't any teardowns on it either. So naturally I took a look at other products using something similar, like the Google Nest 2nd Gen. Ifixit took it apart and found the "magic" behind the wheel. It is the ADBM-A350 by Avago now Broadcom. The chip seems perfect for my application. From my understanding it is a low res image sensor taking many pictures per second to measure movement. Sadly it isn't getting produced anymore and I don't want to use a depricated chip in my new design.

The chips I'm taking a look into:

Closest to a successor comes the APDS-9500 by Broadcom which
"provides an imaging-based gesture recognition function". But all I
could find is one library on github with this sensor.
A very similar (and cheaper chip) is the APDS-9960 and comes with
a library by SparkFun. I would prefer this chip, but I still
don't know if it will even do the job. Do I need to print some sort
of pattern on the inside of the ring for it to work? Apparently the
Google Nest does, but I couldn't find any pictures. My main problem
with those chips is the complexity that come with it. I'm not really
experienced in that kind of thing so a good library is a must.
I guess I would prefer something simpler and cheaper. I did have a
look into optical encoders and quadrature encoders, but I
couldn't find one that suited my application. Also I would need to
print a delicate ring inside the rotating part which is something I
am trying to avoid.

I'm open to any suggestions. Is the image sensor the way to go? Will the libary from SparkFun be enough? Or is the complexity too much to take on and a optical sensor is better? Or should I go for something else entirely like a hall-effect sensor?


texts: NodeMCU ESP8266 DHT22 reading nan (2147483647)

texts:
I am new to electronics and microcontrollers and hope this is the right spot on StackExchange. I have been playing around with an Arduino Micro, connecting different sensors and a display and display data.

I just bought a NodeMCU so I can send sensor values to a database using a DHT22. This is the first test, other sensors will follow.

I am using Arduino Studio with the board configuration for this device.

Everything works fine, Wifi, Serial, but I only get bad readings from the sensor.

I checked 2 DHT22 with my Arduino, they work.
I read that the Arduino has integrated pull-ups and a ESP8266 might not have them, so I added 4.7k and 10k between data and 3.3V. But I am not entirely sure about this.
The DHT22 is using 3.3V on the NodeMCU and the Arduino. Not 5V. -> Arduino works.
I tried different D pins
I tried removing or adding code lines like dht.begin, pinMode, etc.
I used the DHTtest example which also gets bad readings.
I found other projects - Weather monitoring - which showed their wiring. Some of them also did not use a pull-up resistor. I also tried it without.
Wiring checked multiple times -> I hope I'm not blind right now.
Measured the resistors i added -> ok
Measured the voltage between GND and 3.3V -> ok
I don't have an oscilloscope (yet) so I don't know whats on the data line.

So I am doing something wrong here but I can't figure out what.

Thanks for help. Very much appreciated.


texts:
I am attempting to use some of ERNI's PowerElement parts but the associated datasheet and catalogue does not appear to be clear on the associated press fit feet
https://www.erni.com/en/products-and-solutions/detail/225689/
Now an associated part shows the recommended hole size for the press fit holes but I cannot seem to find evidence this is universal across the family
Am I missing something in reading the parts darasheet
https://www.erni.com/en/products-and-solutions/detail/225683/


texts: How many UART can I use in the same time on PIC32MX795F512L?

texts:
As you know there are 6 UARTs on PIC32MX795F512L. But UART1,2 and 3 have two RTS and CTS pins which are common with UART3,4,5 RxD and TxD pins.
Is there a way to use all 6 UARTs at the same Time?


texts: question on diode in the Energy storing circuit

texts:
Please consider the following circuit.

For this case, my following notion is correct?

When v(t) is greater than diode turning-on voltage (v_d), the forwarding current (i_d) occurrs, and then energy will be harvested.
When v(t) is less than v_d, i_d is zero, and then energy will be not harvested.
Thus, the amount of harvested energy is depending on the i_d only when v(t) is greater than v_d.

For example:

First signal's averagy power (E[|v(t)|^2])is less than second one's.
However, the first one turns on diode for a longer time than second one's. (that is, the first signal's sum of red-brakets time is longer.)

In this case, although second signal has more average power, the amount of harvested energy by first signal is much, right??

Thank you for reading my question.


texts:
I have device with one PCB with 6 parallel LEDs (30mA and 3.8V forward voltage each). This very small PCB is connected via 2 vires to main PCB where 555 timer is generating PWM signal based on voltage input (potentiometer). Everything is supplied with 5V DC. And now's question:

It's better to add resistor for each LED or lower voltage to 3.8V on main PCB (with voltage divider maybe)?

Also, on LEDs PBC I have space only for 0603 resistors, which power is lower than LEDs power.

Thanks for help :)


texts:
I am trying to program the Stellaris LaunchPad to blink the red LED at 1 Hz, driven by the sysTick interrupt. I get an error though that I've been unable to solve yet.

The C source I came up with looks like this:

#include "inc/hw_gpio.h"
#include "inc/hw_ints.h"
#include "inc/hw_memmap.h"
#include "inc/hw_nvic.h"
#include "inc/hw_sysctl.h"
#include "inc/hw_types.h"

#include "driverlib/gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/rom.h"
#include "driverlib/sysctl.h"
#include "driverlib/systick.h"

#include <stdint.h>

#define LED_RED GPIO_PIN_1

uint8_t ledState = LED_RED;

void isr( void ) {
    ledState ^= ledState; // toggle LED state
    ROM_GPIOPinWrite( GPIO_PORTF_BASE , LED_RED , ledState );
}

int main() {
    // Set system clock to 80 MHz using PLL and external 16 MHz crystal.
    ROM_SysCtlClockSet( SYSCTL_USE_PLL | SYSCTL_XTAL_16MHZ | SYSCTL_OSC_MAIN );

    // Enable GPIO for LED.
    ROM_SysCtlPeripheralEnable( SYSCTL_PERIPH_GPIOF );
    ROM_GPIOPinTypeGPIOOutput( GPIO_PORTF_BASE , LED_RED );

    // Enable SysTick at 500 ms and register an interrupt service routine.
    ROM_SysTickIntRegister( isr );
    ROM_SysTickPeriodSet( 40000000 ); // 80 MHz ÷ 2
    HWREG( NVIC_ST_CURRENT ) = 0;     // A write to this register reloads the SysTick counter
    ROM_SysTickEnable();
    ROM_SysTickIntEnable(); // <=

    while ( 1 ) {}
}

And these are the command I use to compile it:

arm-none-eabi-gcc \
        blink.c \
        startup_gcc.c \
        -g \
        -mthumb \
        -mcpu=cortex-m4 \
        -mfpu=fpv4-sp-d16 \
        -mfloat-abi=softfp \
        -Os \
        -ffunction-sections \
        -fdata-sections \
        -MD \
        -std=c99 \
        -Wall \
        -pedantic \
        -DPART_LM4F120H5QR \
        -c \
        -I~/stellaris/stellarisware \
        -DTARGET_IS_BLIZZARD_RA1

blink.c: In function 'main':
blink.c:34:2: warning: implicit declaration of function 'ROM_SysTickIntRegister' [-Wimplicit-function-declaration]
  ROM_SysTickIntRegister( isr );
  ^

and to link:

arm-none-eabi-ld \
         -T blink.ld \
         --entry ResetISR \
         -o a.out \
         startup_gcc.o \
         blink.o \
         --gc-sections

blink.o: In function `main':
~/stellaris/projects/sysTickBlink/blink.c:34: undefined reference to `ROM_SysTickIntRegister'

The startup_gcc.c can be found on GitHub: https://github.com/fabhack/SW-EK-LM4F120XL/blob/master/boards/ek-lm4f120xl/blinky/startup_gcc.c

How can I solve the warning and error message?
Why do I have to include inc/hw_nvic.h and inc/hw_types.h when it is also included in startup_gcc.c?
Why is that ResetISR used during linking? I copied it from the Makefile in StellarisWare.


texts: On Cyclone II FPGAs can I apply voltage directly on input pins?

texts:
On Cyclone II FPGAs can I apply voltage directly on input pins, maybe taking it from a Vcc pin? Or should I use a resistor?  The Altera DE2 board's schematics below looks like some input switches don't use resistors.

Schematics


texts: Interfacing 5V to 3V3 devices - MAX3377 damaging my board

texts:
I am using the bidirectional MAX3377 level translator by maxim. I am doing a prototype board and as I test this board piece by piece, everything works until I solder on this part, and my 3v3 rated microcontroller begins to fail.

The low and high side of the boards are appropriately isolated, yet some damage is caused to the chip as soon as i solder on these two level shifters. This has occurred on 3 of my prototype boards already

Could anyone explain why this could be happening? Is it something to do with the 3 state pin? I only have one prototype PCB left, help would be greatly appreciated.

Thanks.


texts: What happens if I interchange the position of the inductor and capacitor in this circuit?

texts:
Shown below is the circuit diagram of a boost converter. What would if I interchange the position of the inductor and capacitor in this circuit? Considering they are both storage elements, there shouldn't be a change right?

With reference to this explanation, why does the inductor discharge when the MOSFET is OFF and charge when the MOSFET is on? Since the inductor is  always connected to the positive supply, shouldn't it charge even when the MOSFET is off? (or) When specifically does the inductor discharge, and why? (The link mentioned something about back emf being developed but I couldn't quite understand that)

In general, what usually happens when an inductor and capacitor are interchanged?


texts:
I've been asked to build this active notch filter circuit for my electronics class :

but I don't understand, where does ground go ? Could someone show me the same circuit with the ground drawn in ?

And, if possible, is there the same circuit with the AC signal drawn the same way as bellow ?

simulate this circuit – Schematic created using CircuitLab

Thanks,

Liam


texts: What's the need for a small capacitor in the negative feedback parallel to a feedback resistor?

texts:
I have the following circuit:

I think I understand pretty much all the aspects of it except for the small capacitor in the feedback. What is the need for it? Judging by the frequency of 1 MHz that is the inverse product of the capacitance and the resistance, I can guess the need for this capacitor arises at high frequencies, when the gain of the amplifier tends to unity. However, I can't figure out the purpose.


texts: Suppressing Transient Voltages - DC circuit

texts:
I have a DC circuit with a 24-26v voltage source (from a battery).

The secondary function of the circuit consists of 2x step down converters, 1x to 5v and 1x to 12v.

The step down converters are connected via an interrupt switch to toggle complete the circuit to them.

In some circuits I've built (I make a lot of these for some projects I make), when either plugging the battery in or switching the toggle on (rocker switch), one or both of the step down converters will burn up and fry, (sometimes there are no issues).

The step down converters are able to handle 26v without issue as per specifications.

Upon inspection, this seems to be an issue of transient voltage spikes effecting the system when energized and rocker switches can "bounce" their contacts which can create much higher transient voltages outside of the spec of the step down units.

The step down units could be changed but my question is can I instead use either a MOV or Zener Diode to suppress the transients? If so, would I simply choose a voltage that I want the transient to be cut off at and what happens when this voltage is reached? Will it effect anything else plugged in (i.e. shorting the system)? This issue only really occurs at power on or toggling the switch. I have also read I can potentially use a high ESR capacitor. Thoughts on any of this would be much appreciated. I want to be able to put about 25 watts max through this.

Thanks


texts:
(Please forgive my ignorance, this came up when trying and failing to construct a homemade current clamp with no background in electrical engineering.)

Suppose I have an ideal wire connected to the live terminal of my 60Hz AC power outlet, then I split it, connect one end to a light bulb, let the other loop  around somewhere for 1/120 light seconds, and then connect it to the other end of the light bulb.

As a layman, it looks to me like there's a voltage across the light bulb, and it should be on, but there's no current on my neutral wire, which is strange. Am I missing something? Is it possible to shift the phase of the AC without a 2500km ideal wire so that I can actually test this?

EDIT: Here's a diagram of the circuit (hopefully intelligible despite my misuse of symbols):

where φ denotes the phase and the dotted line represents a very long wire.


texts: Can I connect 4 fluorescent t8 18w lamps on 2x36w electronic ballast?

texts:
I had my old 4x18w electronic ballast die and they only had 2x36w one in local store. My question is since I have 4x18w lamps can I connect all 4 lamps and do i do 2 and 2 in series and then connect them to ballastr like 2 are one lamp? Is that legit?
Pictures of ballast schemes in attachment.


texts: What does "Power Off OOL" AT command mean for a Bluetooth module?

texts:
I am reading the datasheet for the OVC3860 Bluetooth module and one of the AT commands is 4.50 Power Off OOL #VX. The description from page 21 of the datasheet is below.

[]

What does OOL mean in this context? I intend to use the OVC3860 as part of the BLK-MD-SPK-B module if that matters.


texts:
I want to identify a SMD component of a Nubia Z9 MAX board (NX512JMB)
In the next picture you can see the red square. A 4 PIN SMD component (or 2 PIN component, I don't know).

The green square I believe that is a resistor (like top component) or a capacitor.

This part of the board is the power connection. The components have broken because of a bad charger.

On the same board I found a similar component. The next picture show its label. || F1

I want to see that component (||F1) from the bottom side if it is similar to the missing component layout but I can't find it anywhere.


texts:
Consider the following circuit:

Now I'm asking to impose the base current as zero and $$R_C=452.35 \Omega $$

Now I have a lot of issues with this circuit because I can't find a systematic way to approach this.

Here is the work I've done and problems I found:

1) ASSUME ACTIVE ZONE ONLY USE KIRCHOFF'S LAWS

We are told to neglect the junction voltages when the junction is directly polarized so I should neglect \$U_E\$

Now from Kirchoff laws we will obtain:
$$I_C=I_E$$
$$U_C=-E_C +R_CI_C$$
$$0=E_B +R_EI_E$$

which leads us to
$$I_C=60 mA$$
$$I_E= 60 mA$$
$$U_C=-2.859 V$$

which makes me accept my hypothesis... However if I try now to apply Ebers-Molls equations I get to

$$I_C=\beta I_B + I_{CE0}(e^{\frac{U_C}{u_T}}-1)$$

I obtain $$I_C= 10 \mu A$$

So something is terribly wrong with this approach. Is anything wrong with my equations. My suspect is that I'm wrongly substituting the resistor as a short-circuit to apply Kirchoff laws. Since current is zero I should instead substitute it by using an open-circuit? I never quite understood this resistor paradox from circuit analysis:

Zero current is equivalent to an open-circuit ´
However zero current means zero voltage across resistor from Ohm's law which means a short-circuit.

I think that might be what I'm messing up here. Can someone clarify me please?


texts: I have a couple of these cheap TP4056 battery charger modules and four 18650 li-ion batteries. I want to use all four of them. Is it possible to connect outputs of these modules in a way shown below (in parallel)? Connecting inputs shouldn't be a problem as far as I know.


texts: Doubt about the real need for R and C on micro-controller inputs

texts:
EDIT: as @Connor Wolf noted these are debouncing capacitors, sorry for the poor language

I am not an engineer, I am just an hobbyist who likes to learn and understand the reason of things.

I have had one year and an half of experience with arduino-style and other MCU.
Now i am design a development board for STM32F103RC just for "joke" to improve my abilities. I copied a lot of design especially from leaflab and olimex. For sure who is reading this question have more experience on the field than me, and i am looking for your suggestions.

So coming back to the original question i found on olimex (i can't post the link due to low reputation, see comments) this schematics for a general switch:

or from leaflab's maple rev5 this:

Now my ridiculous year and an half of experience says me that all these components are an exaggeration. I am used to wire a switch without any other component I just use the internal pull up/down of the MCU and I never had a single problem.

While we are here i have other doubts which answers I suspect are: "it is the same don't mind"

I know that pull-up res for the i2c depends mainly on the
communication speed, i have always used 10k, could i continue to use
them or should i use different values?
For the boot-pins olimex and leablab uses different values, 10k and
100k, i hope it is the same
In the link above from olimex, they use a 1M res for the 8Mhz
crystal (i saw this also in the arduino's boards) but they don't use
it in the 32.768Hz crystal, could it cause problems?

I asked these question because I would like to have a few sugestion from people who made some boards and know what is really needed and what is a surplus. I know that a resistor/capacitor more won't destroy my finances, I am not trying to save money but time and space on the board since I will solder all my myself
I hope you will understand these silly questions...


texts:
I need to find the input/output impedances of this circuit (both open-loop and closed loop). I'm not sure how to deal with the Rf resistor as it lies in the middle.

I was thinking to use the Miller Theorem and do this,

Would that be correcT?


texts: Will I be able to keep this circuit on by routing the emitter to the base?

texts:
I'm modifying a current-limiting circuit to work with a transistor instead of a switch. This circuit amplifies a voltage across a sensing resistor via a differential amplifier op-amp configuration. This signal is then compared to a reference created by a voltage divider. If the signal is higher than the reference the output of the second op-amp goes positive. This voltage is felt by a transistor that then allows current to be drawn away from the main circuit (thus turning it off). However, once the circuit is turned off, the second op-amp is no longer positive and current is permitted to flow, resulting in a flickering.

Here's the part I'm not sure about

To prevent this, I'm inserting a second transistor which feels a current at the base if the circuit is over-current. when this happens, current will flow through this transistor into the base of itself and the other transistor. Since Vcc is on both the normally open and normally closed terminals of the relay, current will always flow through this transistor and the switch will remain off until the main power supply is turned off.

Will this work or will the delay between the switch of base voltage cause the strategy to fail? Are there any other issues I'm missing?

Here's a close-up of the area in question followed by the full circuit. (Vcc=24V)

T2 is the transistor I'm questioning and T3 is the transistor that needs a base voltage to pull power away from the relay coil.


texts:
I'm currently doing an assignment and I've been asked to find the maximum power dissipation in a MOSFET. I've been told that this is equal to the the current through the MOSFET times the voltage across it

\$P=I_D(V_D-V_S)\$

simulate this circuit – Schematic created using CircuitLab

Where \$V_D\$ is 26V and \$V_S\$ is variable from 0 to 15V. My only problem is i'm not sure what the relation is for the current? I've so far assumed the current through the drain is equal to the current through the source.

The lowest value of \$R_L\$ is 22.7 ohms and the highest is 10,000 ohms. My initial calculation gave me roughly 15W using the lowest value for \$R_L\$. Is this anywhere close or is there a relationship i'm missing?


texts:
Possible Duplicate:
  Injecting a communication signal over DC power supply lines

I have a pretty simple circuit, but I need to send an output PWM signal through the same place I'm getting my voltage. The voltage is DC, so I figure since my PWM is an AC current, I can use a low pass filter to send the signal through, while getting DC current from the supply. I'd prefer to use a capacitor/resistor filter rather than an inductor, but I'm unsure how I would go about creating one for this particular circuit. My problem right now is that the AC signal goes back to VCC rather than to my AC Input (that also supplies my power).

For an inductor, I'm guessing I'd put it on the path to VCC of my microcontroller? Where would I do it with a capacitor?


texts: I want to design a Class AB amplifier as seen below. But, I don't know how to find the values of the resistors and capacitors. I have found the KVL around the closed loop containing the diodes and resistors to find R; where  R = (Vcc - 1.4V)/(2*I) but I dont know how to determinet I. Is there any way to find I, also my load resistor is 4 ohms. Thanks


texts:
I know there are certain SMD components which can receive a Dupont male connector. I know there are ways to solder male and female connectors to a board directly.

As part of a manufacturing technique, I'm wondering if there is any way on the market to connect wires to a board, without soldering of any kind.

So you might crimp some steel piece to a wire, then that steel piece would go into a through hole in the PCB, where it is ergonomically crimped a second time.

Is there any sort of system in place for connecting wires to boards without soldering? I am looking to build a machine that can do this.


texts: What caused this noise in these servo signals and how do I properly describe the solution?

texts:
Please note that I'm not asking for help in fixing my noise issue. I've already fixed it.
This question is more about describing the issue and using correct terminology.

I have two small 5V servos that are powered by a bench supply about 10cm away.

However, the two servo's signals are carried by a two-conductor speaker wire to an arduino 2.5 meters away. (1 "cable" with 2 conductors, each carrying a servo signal, plus 1 extra separate 2.5m wire for common ground.)

Here is the scope output of the original signals:

Notice that Signal A is showing a huge spike on Signal B's falling edge.
The result was that the servos were not independant, and directly affecting eachother.

Below is the result after placing 0.1μF ceramic caps between each signal and ground, just before the servos themselves:

While signal B still isn't perfect, the servos no longer appear to affect one another.

Circuit with caps:

What would be the biggest likely cause of the original issue, and how do I properly describe how the capacitors solve it?

I am thinking that the issue was mostly the long distance. However since the signals were affecting eachother, I'm wondering if it could also be related to the two signals being directly next to each other (crosstalk)?

I'm also wondering about how to properly explain the solution using the correct terminology.
The caps create a low-pass filter, right? But it that also "decoupling"? Because the signals seemed "coupled" before I added the caps. I'm not sure if calling them "decoupling capacitors" is proper


texts: Enable one or two of the same output via switch (minimalist schematic)

texts:
I'm making a PCB and my real estate is limited.

I am using an AT89C2051 microcontroller, and it only has one serial transmit output.

What I need is a way to set whether the output from the serial transmit pin is sent to only one common-anode device or to two common-anode devices simultaneously. To make things simple, let's make the LED's with resistors in series as the devices in question.

So far, the R2 and LED1 in series where its connected is OK since that's the one device that always shows the data transmitted from the microcontroller.

Because I'm using the standard UART data format, I'd like a pin on the micro (Pin P3.4 in this example) to decide whether LED2 should stay logic high (light off), or LED2's response should match LED1's response.

I'm not sure if I hooked up the transistor the right way for this functionality or if I should use PNP instead?

I added a resistor (let's say 10K) to the NPN base because I needed something strong enough to make the NPN base as logic high if the micro doesn't set the pin as logic low.

To answer a comment, I'll explain...

In reality, the receivers are IR emitters which function like an LED so I used LEDs as an example. The IR emitters are already fitted on a separate board common-anode style (meaning all anodes of the IR emitters are connected to the VCC line)

The separate GPIO pin (P3.4 in this example) is controlling whether LED2 is following the signal of LED1 or just stays logic high.

As for Henry Crun's answer of three schematics, I can explain further.

Left-most schematic won't work for me because the "D2 enable" controls whether the light is only logic high or logic low. There is no way to make D2 in that circuit to either follow the value of D1, or to make D2 off.

Middle schematic won't work for the same reason.

Now could the Right-most schematic work? hmm... maybe someone can explain it more?


texts: Reducing chip count for an ARM embedded system

texts:
It seems like a lot of devices use an ARM SoC + a RAM chip + a flash storage chip. In applications that are very space-constrained, such as ChromeCast dongles, micro drones, or wristbands, it would be very useful to combine these 3 chips into 1 or 2.

Do you know of any solution that combines these three normally-separate chips into 1 package, through either die stacking or die-sharing or some other method, in order to dramatically reduce PCB area?

Thank you!


texts: Calculating the peak voltage of a zener diode output

texts:
I have a problem with this homework, I have to calculate the peak voltage of the output after stabilizing with a zener diode.

My Input Voltage is Vin = 5V + 0.7Vsin (2pif*t) with f=10kHz

My circuit is a simple regulator with no load resistor. The series resistance is 82 Ohms, Zener voltage is 3V, max. current through the diode is 33.3mA. How can I calculate the peak output ? My problem is the offset created by 5V, wouldnt the Zener voltage be reached immidiately with this configuration ?

simulate this circuit – Schematic created using CircuitLab


texts: I have a simple question about the sensitivity list. I read it on some books. It said that the sensitivity list is only important for the simulation. I don't quite understand. Does that mean, if I remove the  sensitivity list, for the emulation on a actual FPGA it won't matter. If I remove the sensitivity list, how does the FPGA know when a process is triggered?


texts: Full-wave bridge rectifier with capacitor filter and ripple voltage

texts:
According to various sources, the ripple voltage of a full-wave bridge rectifier is

$$ V_r = \frac{V_s}{2}fCR $$

where \$V_s\$ is the peak of the input voltage source, \$f\$ is the frequency, \$C\$ is the capacitor and \$R\$ the resistor.

I have simulated this circuit on PSPICE, circuitlab, and built it in real life:
https://www.circuitlab.com/circuit/423m43/fullwave-rectifier/

\$R\$ is \$4.7K\$ and \$C\$ is \$10 uF\$. Voltage source is sine wave with \$0 V\$ offset, \$5V\$ amplitude and \$40 Hz\$ frequency.

All 3 experiments give me a ripple voltage of approximately \$0.65V\$, but the formula gives me \$1.330 V\$ (twice as much).

What am I missing?


texts: Connecting analog power domains in the same chip in ICs (Integrated Circuits)

texts:
I have a following issue, which I didn't see in IC books: I would like to know if it is possible to send analog signals (sin waves) between two power domains in an integrated circuit. The issue looks as follows:

I have never had a problem with sending digital signals between two different power domains as it is done through level shifters / level converters. However, I never thought about sending analog signals between two power domains. Is it done using protection diodes as below?

Of course, signal send from 3.3 V domain is limited to 2.5 V. This sinusoidal 3.3 Vpp emphasizes that signal is send from 3.3 V domain to 2.5 V domain and that maximum signal that can appear on the line is 3.3 Vpp.


texts: Why won't this low pass filter work in spice?

texts:
I just started working with spice and I feel like I'm making some sort of obvious mistake but unsure what.

This works fine:

R1 in out 1k
R2 out 0 1k
Vin in 0 dc 0 ac 1 sin(0 1 500)

.control
ac dec 1000 10 15kHz
plot 20*log(out/in)
.endc

.end

(As in the simulation runs, but it gives me something strange for the gain) Certainly it makes no sense to do a frequency analysis on a simple voltage divider, but it's just a sanity check for the real circuit I'm trying to simulate:

R1 in out 1k
C1 out 0 100nF
Vin in 0 dc 0 ac 1 sin(0 1 500)

.control
ac dec 1000 10 15kHz
plot 20*log(out/in)
.endc

.end

I simply replace R2 with a 100 nF capacitor, and the simulation fails.

The first error I get is:

Warning: singular matrix:  check nodes out and out

This doesn't make any sense to me.

I feel like perhaps I'm doing something wrong with the "Vin" line, as I'm not exactly sure how the "ac" line knows to change Vin (since it's not ever referenced on that line) I am simply trying to sweep 1V AC from 10 hz to 15kHz.


texts: Frequency response of a non-ideal op-amp integrator (input bias current considered)

texts:
Consider the op-amp integrator circuit below. Calculating its frequency response the result is the following:

$$
\underline{H}(j\omega)=\frac{\underline{V_a}(\omega)}{\underline{V_e}(\omega)}=\frac{-1/j\omega C || R_g}{R_1}=-\frac{R_g}{R_1+j\omega R_1R_gC}
$$

If I now assume a non-ideal op-amp and non-negligible input bias current, does that change the transfer function in any way? And why/how?

simulate this circuit – Schematic created using CircuitLab

EDIT: A small signal model approximation

simulate this circuit


texts: How to interface matrix LED with beaglebone black

texts:
I'm a newbie to electronics and for my project I need to control a matrix LED with beaglebone black. I bought a LED click board (https://download.mikroe.com/documents/add-on-boards/click/4x4-rgb/4x4-rgb-click-manual-v100.pdf).

The problems is that I can't find any example on how to control a matrix LED from beaglebone. I've tried reading up on protocols like SPI [https://learn.adafruit.com/setting-up-io-python-library-on-beaglebone-black/spi] (I think this click board uses SPI) but no success.

It would be great if anyone can guide me on how to address the LEDs in the matrix via beaglebone. As there is only 1 pin (RST) on my board that connects to the LED. So I assume I have to send bit signals through this pin.


texts: Using snubber diodes for DC motor and relay

texts:
I code in Arduino and build stuff but don't have engineering background and get lost when trying to figure out datasheets. Already spent few hours on these and just looking for specific advice on which diodes to use (it would be even better if someone explain how to make that determination but just pointing to the right one would be greatly appreciated).

My setup is very similar to this question and have feedback.

I have several of the three diodes at home:

1N4001 50V 1A
1N4148 50V 1A
15SQ045 45V 15A Schottky

Questions 1:
I am getting lots of feedback when switching the larger relay. Not sure how much current larger relay requires but there is definitely a noise when switching that messes up all other arduino connected components. (this scenario is very similar to figure 4 here) Will any of the diodes listed above be appropriate in this scenario or I need to buy something else?

simulate this circuit – Schematic created using CircuitLab

Question 2:
I also have several linear actuators (all of them 12volt and operating at around 3amps). According to this post (figure 2), I have to use 4 diodes for each motor since they are reversing. Will any of the diodes listed above work in this scenario? If not, what model should I buy or what model zener should i get as noted in figure 3 of the referenced post? (I actually wouldn't mind purchasing Zeners instead of what I have - it would be easier to install and more elegant (figure 3 of the referenced post) - if anybody can recommend specific model)

Thank you very much.

More clarification and follow up:

Thank you, Kyle. Quick little background on the project: We are building X-wing fighter to raise money for school STEM program. The project has taken 5 years and we are just focused on finishing it. Frankly, I don't even remember how things were wired and coded (and whether I have the most recent code) and would be very nervous touching anything that has to do with recoding/rewiring that would be needed to put in transistor/mosfets (but I will certainly do this next time). the overall current setup works as is except of getting messed up sometimes because of feedback from motors. Here is the video that has background info and some of the automation that was put in and couple pictures below.

So, right now,  only practical option is to put diodes around the linear actuators. I just wanted to confirm your answer (sorry, with no background and brain exhausted, I am little dense) to make sure I didn't misunderstand anything:

We want diode to have a smaller capacitor so that it charges faster and snubbs the voltage spike faster before it gets too high. This is one reason why Schottky diode would be acceptable. So, this applies to both the relay (across the coil) and the reversing DC motor (actuator), correct?
Thank you


texts:
In Verilog, I have a vector element defined as:
logic [ width_x - 1 : 0 ] x ;

I want to assign the value 0 to x.
Can I always safely use :
assign x = 0 ;

Or should I use ?
assign x = { width_x { 1'b0 } } ;


texts: Can I round-robbin high power LEDs to minimize driver channel requirements?

texts:
I'm playing around with high-power LEDs (the "high" part is relative - 3W). I need 3 channels - 1 per RGB. Because I need independent control of the system, I would need either a multi-channel constant-current driver, or 3 separate single channel drivers. My question is - can I get away with a single channel driver, and use PWM dimming on the LEDs in offset phases? A (very) rough sample as I understand it would be:

simulate this circuit – Schematic created using CircuitLab

(Ignoring the lack of pull-up and gate resistors, and whatever other components I'm overlooking) - does this work conceptually?


texts:
There are a lot of circuits on the internet for lighting fluorescent lamps. But they don't reveal the working mechanism of the lamp itself. I'm more concerned about the theory rather than the practical circuits.

Please consider the lamp as a 4-pin device. And state what signals to apply these four pins.

I'm looking for an explanation like:

  For the first 3-5 seconds, connect the B and D pins to the ground, and apply 9-15V DC to the A and C pins to heat up the lamp. After that, disconnect the C and D pins and apply 200-300V 50Hz AC voltage between A and C pins.

I understand that the voltage levels and time periods will differ between different products, but at least an example on a commonly used one will make the things clear.


texts: Amplifier Causing Problems When Observed at DC

texts:
INTRO: Hello everyone! I am experimenting with audio amplifiers for a while now. I learned how to do an operational amplifier with discrete components and understand all its section and sub-circuits, recently. Then I decided to just skip the hard part and use operational amplifier and output power stage for an audio amplifier to work as desired, instead of troubling with discrete components only. The goal from my earliest experimentation was to create around 100 W audio amplifier but the things went wrong as soon as applying DC to whole amplifier (no AC for now).

PROBLEM: I have built this circuit few minutes ago on breadboard.

simulate this circuit – Schematic created using CircuitLab

When I checked only output power stage with VBE multiplier (without MC1458 op-amp) everything worked just fine. But when I connected op-amp to it directly (no AC coupling - switch position B), as I increased Vce of VBE multiplier just a tiny bit, then the current through both upper and lower output power quadrants suddenly increased to 2A or more and stayed there or it was swinging like there was some kind of heavy oscillation within amplifier! As soon as I added AC coupling capacitor (switch position A), the darn thing worked as expected when Vce of VBE multiplier was changed! As it was increased with potentiometer P2 slightly also the quiescent current through power stage increased slightly - as expected!

Why did such heavy oscillation occurred within my amplifier circuit when there was no AC coupling capacitor between voltage amplification stage (MC1458) and output power stage (upper and lower Sziklai pair with paralleled power transistors)?

NOTE: C3, C4, C5 and C6 represent AC bypass to avoid distortion when AC is applied to such circuit. At the collector and/or emitters of power transistors Q4, Q5, Q6 and Q7 there are no low resistance resistors for improving thermal stability of those because I have no low resistance (lower than 1 Ohm) high power resistor. Also, I have replaced MC1458 with another one (same part), but the results were similar (talking about example with no AC coupling capacitor).


texts: Is a 2W resistor sufficient to dissipate 0.6W of power?

texts:
I'm looking at reducing the power of a 24V 0.1A fan by half. I've calculated that I need a 240 ohm resistor for this purpose. But I also need to choose the wattage.
I'm using the following website for my calculations:
https://www.blackfiveservices.co.uk/fanspeedcalc.php?Voltage=24&Current=0.1&Target=12
It summarizes:

Power dissipated by resistor:  12V * 0.05A  =  0.6W

I've read that when choosing a resistor I should double the required wattage on the part.
Is a 2W resistor sufficient?
I'm trying to do this as inexpensively as possible as high watt resistors are expensive.


texts:
I'm using a array of hydrophones to localize an underwater pinger (37.5 kHz and 45 kHz) and I'm thinking of using LM567 tone decoder as a frequency filter. The other option is to design a custom bandpass RC/RLC filter.

What are the pros and cons of both options?
What order and type of bandpass filter should be built and why?

Edit: this will be deployed on an AUV with limited space. Planning to use a Teensy 3.6 ARM board for pinger localization algorithm.


texts: How do I transfer contents of one memory to another in one clock cycle

texts:
I have a 9 X 8 memory with me, there are 9 memory addresses with a byte of data in each.
I need to transfer the contents of this memory to a sub module but I'm one cycle.
    module top (input rst,
    input clk)

    reg [7:0]mem1[0:8];
    wire data_out;

    smallmem sm
     (.clk(clk),
      .data_in(data_out));

    endmodule

    module smallmem (input
     clk,input [7:0]
      data_in )
     reg [7:O] mem2 [0:9];

       .
       .
     endmodule

I need to transfer the whole data of mem1 of my top module to mem2 of my submodule smallmem.
Also, can the memory be written this way?
Consider the following snippet
module(input clk, input rst);

reg [7:0] buff [0:8];
reg [215:0] mem [0:254];
// Assuming I have a memory 'mem' with the dimensions as stated above
// and assuming the value of reg addR at the current posedge of clk is
//0.
always@(posedge clk)
begin
for(n=0;n<9;n=n+1)
   begin
    mem[(addR+0)][215-(24*n):208-(24*n)] <= buff[n][7:0];
    mem[(addR+1)][215-(24*n):208-(24*n)] <= buff[n][7:0];
    mem[(addR+2)][215-(24*n):208-(24*n)] <= buff[n][7:0];
   end
end

Assuming the value of addR is 0.
If I run this design for one clock pulse will all the contents of memory 'buff' be written in the first three address of my memory 'mem'?
I want content of addresses 0,3,6 of 'buff' to go in 1st,4th,7th,10th,13th,..,25th byte from MSB of 'mem'.
Content of address 1,4,7 of 'buff' to go in 2nd, 5th, 8th, .. ,26th byte from MSB of 'mem'
and
Content of address 2,5,7 of 'buff' to go in 3rd, 6th, 9th, ... , 27th  byte from MSB of 'mem'.


texts: Different voltage levels for LCD and microcontroller

texts: I want to interface my microcontroller (ATmega32) with a 2x16 LCD. I am powering my microcontroller with 3.3V, and I need to use 5V with the LCD. Will be there any problem with that (i.e data signals from the microcontroller to the LCD will have  logic 3.3 while VDD and Backlight for the LCD will be powered by 5.0V)


texts:
I've been reading the datasheet for the Z80 PIO chip a lot in the last few weeks, and I still don't fully understand what it's supposed to do. Take this diagram, from the Z80 CPU datasheet:

This is an example of how to use the Z80 CPU with the Z80 PIO and a ROM chip.

So, my understanding of the Z80 PIO is this:

The CPU can send data to it so that it can send that data to perhipherals such as a keyboard.
It can send data to the CPU from peripherals.
It can also be used to control RAM chips.

Is any of this wrong?

Mainly, I'm confused as to exactly what the ports are. Do I attach one peripheral to each port? If this is the case, how would I control, say, three peripherals?

I'm also confused as to why A0 and A1 control B/A and C/D pins. Does this mean I would address a peripheral attached to port A with the address bus looking like: XXXXXXXXXXXXXXX0? (Since then A0 is low?)

If my question's unclear, I'm looking for a clear explanation of what the PIO is for, and what exactly the ports mean, and what they're for.


texts:
Trying to build a simple circuit to power a small pump while the sun is out. Here are the specifics:

Solar Panel (60 cell mono panel) Open circuit voltage 36.4V DC, Short circuit current 7.96A.
Pump 12 V DC, 9A max

Using E=IR ,  R=E/I, (36.4-12)/7.96 =  3 ohms
Power = V(sq)/R = 24.4/3 =198 watts

I purchased a resistor that meets these requirements and hooked everything in series. (Solar panel lead to resistor, resistor to pump, and pump to other solar panel lead.

The pump does not turn on when the panel is in the sunlight.
I measure the voltage coming out of the panel and it is within specification.
I also tested the pump by hooking it up to a car battery and it works fine.

Any ideas what I am doing wrong?


texts: Why does I1=0, What prevents current of primary from  flowing - the voltage source still activated so why there is no current?


texts:
Hi! I am an absolute newbie at electronics (though an Industrial engineer by qualification). I discovered this diagram for a VCO from the datasheet for an LM 358. I assumed when they say 1/2 LM 358 they mean one of the two op amps that are inside the LM 358. So I assumed they meant that the output of one Op amp will go into the input of the other, meaning I connect pin 1 to pin 6 on an LM 358. So I set up the circuit accordingly but it doesn't work so I deduced that's not what they meant when they labelled the op amp 1/2 LM 358.

Could someone please explain how I am supposed to make this and tell me what 1/2 LM 358 is supposed to mean?
What does the V+/2 as a non inverting input into the second op amp mean? Am I supposed to put in half the voltage at this point? Half of what?
I read that VCOs are tough to tune etc and are usually very complex to build. I don't know what means. Can I make this one easily?


texts:
Wondering if super glue could be safely used on a PCB to cover exposed traces or jumper wires.

I know it’s non conductive but is there any type of damage that could occur?

I normally use green solder mask that cures with UV light but ran out and need to finish a repair using jumper wires that need to be insulated


texts:
I have two solar panels in series totaling a maximum of 80 VDC and 500 Watts.  I believe that would be a maximum of 6.25 Amps.  Could a 20A 120/277V AC switch handle that since 6.25 Amps is a relatively low current? If not what about a 30A 120/277V AC be able to handle it?

Update: The reason I want a DPDT switch is so I can easily switch my two panels setup between being series and parallel. Each panel is 250 watts with a 40 volt output. Series would give me 80 VDC at 6.25 Amps and parallel would give me 40 VDC at 12.5 Amps. Because of shade issues on the RV, there would be times that one setup would be advantages over the other. The switch would not be switched often. I am wondering if a knife switch would serve my purpose better.


texts:
I found the cable (1533576 - Actuator/Sensor-Cable, M12 Socket - Open End Connector, 2m, 4A, 250V, Phoenix Contact) here that is claimed to handle 4 A and is then written that it has a 22 AWS cross section gauge, 4x 0.34 mm².
How this could possibly be? There is the table here that says the gauge 22 can is only allowed to carry 0.92 A for "power supply". Even all four wires together cannot make it as much as 4 amps. Ok it would be 7 amps for "chassis wiring" but if another answer about the chassis wiring is right this only applies for the single wire free in the air and not in the bundle. All 4 wires in this cable are very obviously in the bundle.
I was planning to use 14 gauge wires for my 5.5 A (5V) power part. They look thick and thinner wires worked fine on my workbench during prototyping. Does this mean that my power circuit is over-engineered?
The possible answers could be:

Forget about this cable, you need the gauge 14 to supply exactly the power to that PCB to be safety compliant (5.9 A, your SBC draws 5.5 A so table calls for this gauge).
Something else? Is it so that I do not actually need the wiring that heavy to be safety compliant? Or some consultant can waive this requirement?


texts:
I'm trying to convert Hex number into Decimal ASCII representation in Verilog, I've done the next code that converts successfully but this it cost a lot of timing for my design, could anyone help me with any suggestions for optimizing this code?

module Hex_To_ASCII
#
(
    parameter NumberOfDigits = 14,
              InputSize      = 47
)
(
    input clk,

    input go,

    input [InputSize -1:0] Value,

    output reg [NumberOfDigits * 8 -1:0] ASCII
);

integer i;
integer j;

reg [7:0] ASCII_Integer [0:NumberOfDigits-1];
reg [InputSize - 1:0] hexInteger_tmp;
reg [NumberOfDigits*8 -1:0] full_ASCII_tmp;

reg start;
reg stop;

always @ (posedge clk) begin
    if (go) begin start <= 1; stop <= 0; end
    if (!go) begin start <= 0; stop <= 1; end
end

always @ (posedge clk) begin

  if (start) begin

      hexInteger_tmp = Value;

      for(i = 0; i <= NumberOfDigits-1; i = i +1) begin
          ASCII_Integer[i] = ( hexInteger_tmp % 10 ) + 8'h30;
          hexInteger_tmp = hexInteger_tmp / 10;
      end

      full_ASCII_tmp = ASCII_Integer[NumberOfDigits -1];
      for(j = NumberOfDigits -2; j >= 0; j = j -1) begin
          full_ASCII_tmp = {full_ASCII_tmp, ASCII_Integer[j]};
      end

      ASCII = full_ASCII_tmp;

  end

  if (stop) begin
      for(i = 0; i <= NumberOfDigits-1; i = i +1) begin
          ASCII_Integer[i] = 0;
      end

      hexInteger_tmp = 0;
      full_ASCII_tmp = 0;
      ASCII          = 0;
  end

end

endmodule

Thanks Guys!


texts: Decoder inputs needed given 32 registers

texts:
I have a couple of questions about decoders. My first is this:

If I have a register bank with 32 registers, how many inputs are needed for the decoder and why? I think that you need 5 inputs for this decoder because 2^5 is 32. However, I do not know why this would be the case, or if I am even correct.

I am also curious as to how many inputs are needed for a decoder if the memory has 1 million locations, and why.


texts: What does voltage mean on a ground wire? (Neon-lamp screwdriver)

texts:
This question has some implications on home related work with mains. Never take what you read on the internet as the truth when lives might be in the line. That is how I'll be treating potential answers also.

In an old household on some sockets the testing screwdriver lights up very a little when the ground is tested. The light is significantly weaker than on the hot wire.

The ground voltage can't be felt to the touch, the only way it's detectable is with the neon lamp screwdriver.

Other sockets don't have that leaking voltage, the screwdriver doesn't light on at all.

The house does have an RCD switch which works.

Assuming anything can be expected from the house wiring what could be the cause of the voltage on just some grounds?

Update

There was a good comment if I want an engineering answer or how to fix this practically. I would like an engineering answer in the form of a summary of plausible theories in the EE jargon that would fit this behavior.


texts: ESP32 randomly dies after 10 minutes use

texts:
I've posted here before (this) and this could be considered a followup post.
I've taken all the feedback into consideration which would make me belief to have a working version.
However, after about 10-20 minutes of use, the thing just dies. It straight up dies. No output anymore over UART, it won't even  boot. There is still ~3.3v on the 3v3 and chip_enable pins, as well as on GPIO0 (boot mode) which has an internal pullup.
Here is a screenshot of the schematic, and here is a link to the pdf, where everything connected to J1 was left unpopulated. None of those transistors were populated.
All the unused pins on the ESP32 were left unconnected/floating.
Here is also a link to the pcb layout.
Here is the datasheet of the LEDs that were connected, I bought them as a generic WS1815 ledstrip, I cannot find the manufacturer of them so these might not be the exact LED.
What could be the issue?
The only thing I could think of is that, somehow, 5V shoots back into the ESP32, from the LED strip (the WS2815 have 5V logic level.)
In the two boards that I have tested, I tested a ledstrip connected to J3.
I'm at a loss, any help is appreciated.
To the remarks about ESD, it's not that I'm not at all concerned about ESD, it's more that over the past years I've worked with many custom ESP32 board that did not have any kind of ESD protection. I have never had any issues with those boards.
To the remark about the power supply, I have tried connecting the power supply to another board with the same power cirtcuit, which worked like a charm, the baord stayed alive for the couple hours that I left it on.


texts: I am trying to design an Li-Ion battery charger and I am using an LM317 chip. I created a symbol and subcircuit file (LM317.sub) but LTSpice cannot find the subcircuit file. I am not sure why so please help. Here are the symbol and subcircuit, along with an image of my charging circuit. The capacitor in the circuit will be replaced with an Li-ion battery.


texts: Minimum and Maximum temperature for a copper wire to work?

texts: Is there a minimum and maximum temperature that a copper wire/s will still work on. Meaning that current will still be able to go through them.  Let's say that I have battery that is heated or cooled depending on the environment, and that battery controls a light, that is also heated or cooled, and the wires connecting it are exposed to cold or hot environment. Is there a specific temperature, max / min, that will ensure that current still passes through the wires. I know this might depend on the size of the copper wire, and the specific gauge, but I am considering wires between 18 and 26 AWG. I also figured out that the melting point of cooper is about 1,085 °C, therefore that will in theory be the maximum temperature that a copper wire will be able to operate, I assume. And I am not sure about the minimum temperature.


texts: FET Written Inside Comparator/Op-Amp Symbol

texts:
I'm in the process of importing a bunch of old schematics from a 70's era synthesizer into KiCAD. In the process I've come across a symbol that I can't make sense of. It looks like this:

Does anyone have an idea of what part this is? The only other IC used in the schematic is an LM741. Could this just be another LM741? Why does it have FET written inside it?
Edit: The schematics are dated December, 1975. So the parts would have to be older than that.


texts:
I need to control 12v Fan with 3v3 uC. I need to stop and start it using uC gpio pins. I tried to use this schematic first:

But when I set uC gpio (14 in my case) to 0, fan starts to make a weird noice. I measured voltage on the fan and found about 6v on it. I replaced fet with the 2N7000 - the same result. So, I replaced fet with the npn then (removing r4) - the same.
I thought it might be the problem with other pins, so I removed pins 3 and 4 in order to disconnect them - the same.
Please help. I searched the internet and this site as well and found a lot of answers that it should work either with n-ch or npn transistor. What am I doing wrong? I didn't try to use 2 npns yet since a lot of sources says it shall work as it is.

I use tps62172 to power uC from the same 12v power supply as fan, so the ground plane is common.


texts: I'm using the circuit in a disposable flash camera to "discouage" squirrels from using my bird feeder. I've soldered across the charge button so it is always in charge mode but I've removed the capacitor and hooked up my perch leads where the capacitor was. The perches are wired  such that you have to touch two to get the mild correction. The problem is the battery runs down in a day. If I put a capacitor back in the circuit would that keep the battery from running down?


texts:
Guys My doubt is that for the following cascode configuration how can the minimum voltage needed at the drain of M1 be Vt + 2 Vov for M1 and M2 to be in saturation ?? Vov is the over drive voltage whihc is Vgs- Vt.

For saturation considering that Vds > Vov. At transistor M1 the minimum voltage should be 2Vt + 2Vov in my opinion. But it is said that it is Vt + 2 Vov , how is this so ??


texts:
I am trying to set up an STLINK-V3 in Windows 10.
I downloaded and installed the USB drivers from STSW-LINK009, as suggested in TN1235. However, ST-LinkUpgrade (STSW-LINK007) and the ST-LINK Utility (STSW-LINK004) both say "No ST-LINK Detected".
The ST-LINK I am using has previously connected to another computer; I can get the green light on using Ubuntu (though there are problems there too).
However, in Windows 10, it appears that the driver is not loading. Device status says:
This device cannot start. (Code 10)

Insufficient system resources exist to complete the API.


texts: What are good books/reading material for Physical Design

texts:
I did not find a tag for asking questions related to Digital design - Frontend / Backend(Physical) on StackExchange. So I proposed one there on area51. So for time being asking my question here -

1]I am looking for a book on Physical Design/Backend design for beginners. I am basically a software developer,having overview(no hands-on) of Digital design process(both frontend and backend). But now as part of job, I have to start contributing by doing "real work" on Physical design for a SoC. What book would explain in detail, almost all aspects of Physical Design, in a step by step kind of manner.

If you point of any other reading material like blogs/IEEE-papers/websites/forums which talk about physical design would also help me.

Thank You.

-AD


texts:
In AC circuits at the meter we have line and neutral going into the meter and then all devices are connected to it. For each and every device, we require a line and a neutral connection. If I want to measure current in a particular device so can I measure it in the following ways:

Introducing a current transformer in the line before the current is entering the device?
To measure current at the neutral end, i.e after load.

Is my last point correct or not?


texts: Why do Tesla and other manufacturers use AC motors?

texts:
I know Tesla and others use AC motors. I read a lot and no one really provides a good answer. I know they are using an AC induction motor, and with Model 3 also an AC synchronous permanent magnet motor also referred to as brushless DC.

Basically my question is why does almost everyone opt to use frequency drive to control their motors?

I know they could use synchronous permanent magnet motors and run in from DC but they still run it on AC. What advantage are they gaining? Better control, cost, torque?


texts: Voltage of inductor/transformer with a square wave input

texts: I'm kind of having trouble thinking of what the response of an inductor to a square wave input would be, as well as the response of a transformer (I found this answer for a square wave input to a transformer a little incomplete or unclear: Square Wave input into Transformer).  It's my understanding that the graphs for the current and voltage of an inductor when a circuit is closed are exponential shaped, so for a transformer with an idea square wave input (modeling the primary as an RL circuit) what will the output waveform be?  Would the output voltage be a exponential triangle wave, a square wave with the rising portion exponential portion, something else or am I not thinking of this right?


texts:
I've got a schematic that i found on the internet. The schematics is for a solar pwm charger
designed around a microcontroller in this case a arduino.

The problem lies in the values for the capacitors they are confusing to me.

The following is what i made out of it:

Non Polarized:

2 47nF
1 1µF
1 220pF

Polarized:

1 4.7µF
2 1µF

Is this correct and why did he label values this way, did he use some sort of standard or is it purely random?

(for example why dus he sometimes use 1µF but in other parts 1000nF, use 47n instead of 47nF or use 4µ7 instead of 4,7µF)


texts:
I'm designing a home made game console motherboard, and want to integrate the ATI Mobility Radeon 9000 GPU in it. The problem is, the Northbridge I picked only supports PCI Express, and the GPU uses AGP x4. So I found a second Northbridge chip designed for AGP, but as far as I know, is not designed for my processor (Intel Dual Core). I'm thinking about attaching both Northbridges to the CPU, having the AGP one solely control the GPU, and the other control everything else. So here are my questions: 1) Is this method practical, as in, is it possible to wire everything correctly so they work, 2) will the AGP chip work without having RAM attached to it, 3) If my method won't work, is there a way of bridging the PCI Express interface to the AGP x4 interface?

My two Northbridge chips are the GL960 for the main chip, and the 855GM for the AGP. I don't want to get different chips, because I have these two on hand from scrapped laptops.


texts: Tantalum Capacitor Explodes When Engine Starts

texts:
I designed a circuit using a SMPS voltage regulator based on the tps65261rhbr triple synchronous buck converter. The circuit is rated for up to 18V. It is connected to a 12V lawnmower battery, which also starts and powers a gasoline engine that returns charge to the battery with an alternator.

The circuit has worked perfectly over many hours of testing and switching power on and off before I connected and started the engine. Immediately upon starting the engine it failed: one of the 25V 47uF tantalum capacitors (TPSD476K025R0150) feeding the SMPS exploded.

My oscilloscope has a max of 10V, so I can't see what the input voltage waveform looks like when the engine starts and runs. I tried anyway, and I see that when the engine is started the voltage briefly dips under 10V, but outside of that brief blip it is clipped to 10V so I can't tell what's happening. I assume the voltage must have exceeded 25V for the capacitor to explode.

I'm considering switching to higher voltage (50V?) aluminum polymer bulk capacitors and a high input voltage rated 12V LDO before the SMPS to protect against input voltage spikes.

Does this seem like a good approach? Should I get a better scope or build a voltage divider to see what's really happening? Does anyone have any experience with powering circuits from an engine alternator and battery in parallel that can weigh in on this power supply design?


texts:
I am using an ESP32 board to communicate with an LCD and an I/O expander using an I2C bus. I am running a FreeRTOS based code.

I am using 2 separate threads for the LCD and I/O expander each to concurrently access them. I am trying to use a mutex to implement thread-safe I2C. Do I need to install and delete the I2C drivers(basically setting slave address) within each mutex, every time I enter a thread, since they are 2 different slave addresses?

Is there a better way to perform concurrent i2c communication?

Thanks


texts: Can a gear motor w encoder be 60 ft away from controller?

texts:
This is my first time posting so please forgive any ignorance that may come across.

I'm considering hooking up two gear motors (Devantech 24V, 49:1 Gear Motor w/ Encoder) to a motor drive (MD49 - Dual 24 Volt 5 Amp H Bridge Motor Drive). I'd like the gear motor to be about 60 feet away from the motor drive, connected through wiring.

Would this distance cause any issues with feedback/control etc through voltage or current losses?

Also, I assume that the motor controller will cause one motor to go CW and the other CCW?

Links:
http://www.robotshop.com/en/devantech-2 ... coder.html

http://www.robotshop.com/en/devantech-m ... river.html

Thanks in advance,
Radek


texts: what is the electrical component symbol in datasheet ABB M1M 10

texts:
I am planning to install a power meter ABB M1M 10 with Delta connection (2E) 3 phase 3 wire system. However, I fail to recognize the electrical component symbol in the red area of the attached image below. May I know anyone at here able to recognize this component symbol? May I know what is the symbol standard that I can refer to?

if my explanation is not clear enough, please refer to attached link pdf ABB M1M  part 6.2
link:
https://library.e.abb.com/public/053a9148943a411c8d134fc7a9db366c/Installation%20Manual%20M1M%2010.pdf


texts: Why I2S is better for transmitting audio compare to SPI

texts: I am trying to understand why we use I2S is better for transferring audio than SPI as I2S has less bandwidth compare to SPI.


texts: Please, help me understand the specsheet on page 2-22. The table says that 3.3V standard supports 12mA drive strength, but there is also a "software" defined strength. What is it? There is also a "wide range" (table 2-29 second row, and notes 1 and 2). How do I know if my FPGA is set to wide range or not? The settings in the IO interactive tool (see below) do not provide this information. In fact, bank3 allows me to select 16mA and 24mA as well. How do I interpret all this information and apply? Specifically, it seems like my FPGA is operating in the wide range mode and thus I get only 100uA drive strength even if the setting says 12mA.


texts: list of general purpose smd transistors, diodes and mosfets

texts:
I want to start with building up a little stock of smd components.

But i'm not sure where to start. Is there a list of general purpose smd Transistors, Diodes and (mos)fets?

Thnx in advance


texts:
I need to simulate a realistic signal voltage triangle waveform in Mathematica.  I know that a real waveform won't have sharp corners, but I don't remember exactly what a real triangle wave looks like. I have been using the waveforms suggested here and am curious if they are realistic.

My simulations are in the .01 GHz to 2 GHz bandwidth.


texts: verilog: binary code decimal and gray code counter implementation

texts:
I am trying to implement a 8-bit counter that does both BCD(Binary Code decimal) and gray code sequence. If the input control = 0, the circuit will count in BCD and if the input control = 1, the circuit will count in gray code sequence. Here is my implementation:

module grayBCDcounter(
    input clk, control,
    output reg [2:0] y1,
);

reg [2:0] state          // there will be 8 states: 1st state :000
                         // 2nd state: 001, 3rd state: 010 and so on
                         // my last state will be 111

parameter s0=3'b000, s1=3'b001, s2=3'b010, s3=3'b011,
                s4=3'b100, s5=3'b101, s6=3'b110, s7=3'b111;

always @ (posedge clk)
begin
case(state)
s0: state <= s0;
s1: state <= s1;
s2: if (control == 0)
       begin
          state <= s2;
       end
    else if(control ==1)
       begin
          state <= s3;
       end
s3: // and so on
endcase
end

always @ (posedge clk)
   begin

   if (state == s0)
     begin
        y1 <= 0;
     end
   else if(state == s1)
     begin
        y1 <= 1;
     end
   else if // so on
   end
   end

endmodule

When control variable is 0, I want to execute s0,s1,s2,s3,s4,s5, and so on as you can see(BCD), and when control variable is 1, I want to execute s0,s1,s3,s2,s6,s7,s5,s4 respectively (gray code)

When I run a test cases on it, it somehow only prints s0 and seems to be constant throughout the execution. My guess is that the state never goes off from s0.

Any tips on how I should implement the codes?


texts:
I'm using Synopsys to synthesize designs. I've noticed that when I synthesize exactly the same design several times, I get different synthesis reports.

When I launch the tool for the first time, synthesize the design, read the report ; then, close the tool and resynthesize the same design, then I get the same results. But if I perform the same synthesis without closing the tool, results aren't the same.

I think this must have to do with some history files, but I'm not sure. Anyone else had this problem ? How can I solve it ? Is there a way of reseting the tool in a script so that this does not happen when I perform synthesis without quitting the tool ?


texts:
I have a small project with AT89S52 and LCD 16x2. I build circuit and simulation in Proteus. It works normally. But when I build PCB, LCD can't display the value.
I just adjusted rheostat to change LCD's contrast and it worked.
Can you told me the mistake that I have?


texts: does changing the cable length of NTC temperature sensor affect accuracy?

texts:
I'm using an off-the-shelf STC-1000 temperature controller, popular with homebrewers, that uses an NTC sensor to read temperature and switch on a relay to cool or heat when the sensed temperature exceeds the set limit.
I needed the 2m cable of the sensor to be longer, so I extended it by 3m.

By how much could the extending the wire affect the accuracy of the sensor?


texts:
What is this MOSFET for?

First I thought it's some sort of over-voltage protection but right after this, there's Zener diode doing the same?


texts: Single MOSFET motor driver with oscillation on output

texts:
I'm trying to drive a small DC motor with a PWM with the circuit below, where I'm using a TIL111 optocoupler and a IRF510N MOSFET. The PWM (50% duty cycle) is generated by a MCU STM32F103C8T6, the +3.3V source comes from this MCU and the +5V source is another one.

The motor drives, but the waveform over the motor looks like the one below (sorry for my oscilloscope). The image isn't clear but what happens is that this output have some waves (resembling coil discharging waves) when it should be off, or 0V (the ON semi-period is working ok). Since I have a +5V source and a 50% duty PWM, I should measure 2.5V over the motor, but, with this signal, I'm measuring 3.55V.

If I remove the motor and put some 120 ohm resistor in its place, I can visualize the correct waveform below. I also verified the waveform over the opto and over the MOSFET's gate, and it's working fine (with or without the motor).

I'm using this dummy dc motor below, but I have tested with other two dummy motors and having the same result. Actually, I tried to drive these motors with a TIP before, using a similar circuit; that time, I changed pretty much all the components (TIPs, resistors, diodes, motors, protoboards) and I still ended with this same result. If someone could tell me some tip about why I'm having this behavior, I would be grateful.


texts: Differential amplifier with feedback resistor

texts:
In this circuit, if a resistor of 1 M\$\Omega\$ is connected between A and B, what is the effect on the stability of the quiescent point?

The analysis I made led me to believe it would provide positive feedback and thus won't stabilize the point, but I dont feel safe enough as to assure it. Which is a good method for verifying this? I couldn't think of a way to check it in a circuit simulation


texts: How to make perfboard circuits more compact

texts: So, I've been working on my prosthetic limb for quite some time, and I've sorta bumped into a few problems, while the circuits I've made work, they don't fit inside the arm. Mostly because I have tons of opamps (around 28 for a state variable filter, it has settable Q, so I couldn't resist, but I've used quad opamps), and the solder job has been a nightmare. I need to fit it in a small space, and I'm okay with components protruding up and down the board. Is there some way I can me my circuits more compact? I'm thinking of using smd insted of DIPs, but I want a few more options..


texts:
what is the best material for sticking power electronic devices into the heat sink.

We are using of Heat-resistant silicone paste similar to this photo:

thanks a lot


texts:
Schematic

The arrows are GPIO's

I want to be able to close multiple switches at once in any particular order in order to manipulate GPIO's manually. I could give each GPIO its own resistor, but when I close multiple switches the current will increase (by 2, 3, 4 times) reducing battery life. I tried to find a way where each GPIO would share the same resistor and be properly pulled down, while still remaining isolated by the switches. Would the above circuit work?

In particular, when the switch is open will the GPIO be at ground as I want it to be, and when the switch is closed will only the specified GPIO be high?


texts:
We have an application which accepts streams over IP and displays it on the LCD Screen.

We want to test the Ethernet plug-in/Plug-out test. Do you know any IC which can simulate someone plugging in and unplugging the Ethernet cable. I need something that is a high speed Ethernet mechanical switch. And it should be controlled by software.

Do you guys have any idea of such IC/Chip.

We used MAX4886 for HDMI Switching it provided SEL pin for controlling between HDMI inputs

https://datasheets.maximintegrated.com/en/ds/MAX4886.pdf

Is there anything similar to this for Ethernet


texts: Why is does my board stop responding periodically when the motor is hooked up?

texts:
I have built a stand alone Arduino type board.  It will run all day long as long as no actuator is hooked to the relays, the voltage on a voltmeter shows when the motor changes direction properly.  The problem is when I actually hook up an actuator (9amp), I'm using a 10amp relay it will run for a bit (no set time, it changes) then just stop.  I have hooked up a Oscilloscope to the 5v vcc line of the 168P chip and when the relays change state I get quite a bit of garbage on the scope when the relays change state, it shows the min voltage spikes anywhere from +8 to -12 volts, sometimes this freezes the board, sometimes it resets the board.  Could someone look at my schematic and give me some clue as to what to look for? and any input to make it better?  I am pretty new at this, so please, be easy on me. :)
The board runs off an Arduino sketch which is nothing more than a switch that tells the actuator to go up, wait 5 secs and go back down and wait until the button is hit again.  Like I said, works perfect as long as no actuator is hooked up to the relays.
The board is setup with a jumper J56 and J70 that puts the relays connected to I/O 5 and 6 on the processor.


texts: How to set a rule for pads of just one component in Altium Designer

texts: I am designing a PCB for a STM32 MCU, whose PCB model contains pads very close to each other (clearance < 10mil). How can I set a rule for pads of this specific MCU (not other components) on my board in order to allow designing pcb with this model and meanwhile keep the predefined rule (clearance > 10mil) for other components? I am using Altium Designer version 13.2.


texts: Damaged CMOS-transistor behavior in th IC circuit

texts: ) I've always wondered what will happen with CMOS transistor in the IC if it is exposed by over-current or over-voltage? I mean what are the possible outcomes. Will the CMOS be like in short circuit, circuit break or some intermediate state with some sort of an arcing maybe... Will it be always closed or always opened? Or maybe its channel resistance will change...  For example let's suppose that we consider two digital CMOS integrated circuits with push-pull outputs working on each other (directly connected without serial resistors). Can something bad happen? And how can I diagnose the outputs state with a multi meter in that case? Thanks!)


texts:
I was reading an article yesterday about circuits and IC's in deep space and how they need to be operable at high temperatures. A few questions popped up when I read this article. Today there are many and have been many missions/projects of surveillance ops in our outer universe Furthermore, NASA has put together missions involving asteroid research as well as JAXA. I realize there are numerous control variables that take a play aboard these specific systems. I have a few questions I thought someone could answer briefly or if to extensive could post a source where I could refer too for further information.

Does atmospheric pressure effect operating temperatures of circuits and/or IC's implemented on a system in space?

Does radiation/gases effect operating temperatures of a circuit and/or IC's in the same scenario above? If so, does the engineer have to take in precautionary measures in the construction of a circuit if the system might be exposed in low orbit of planetary systems?

What kind of precautionary measures are we talking about in GENERAL terms? Are there any good resources out there that explains how circuits can generate heat and tactics used to lower their levels of heat given off?

Thanks for any advice or information. Again, if information is to extensive please attach a source that I or anyone else could use for further information/research. Thanks again.

V/R
Shane


texts:
I'm reverse-engineering the data bus inside a projection clock to find out how to drive the projection without the clock. I use PulseView with a logic analyzer.

What I (think to) know so far: It seems to be SPI using 3 wires but in total there are six wires: VCC (D4), GND (D6), MOSI (D0), SCLK (D2), CS# (D1) and the last one (D3) looks like a strange "2-stage" CLK-signal and I'm unable to (fully) understand its use.

On the left you see the six connectors. I connected them to be color-consistent to the colors in PulseView (white = D1). Yes, the connection looks "dangerous" now but when I collected the data it was one-to-one. On the backside there is a connection from ORANGE/(D3) to the AUTOLIGHT1 switch at the top and in fact, the projection is off, if ORANGE/(D3) is set to 1 (permanently). Here are the PulseView pictures:

A "start" of D3:

Do you have any idea what (D3) may be or what I could test to find out?


texts:
I am designing a circuit that needs to output 5VDC @ 1A.  I'm trying to use a wall transformer to step the voltage down to 12VAC.  The next step is the diode bridge and ripple capacitor.

The ripple voltage equation is:

$$V_{ripple} = \frac{I}{2fC}$$

I = load current (1A)
f = AC frequency (60Hz)
C = Filter Capacitor (? uF)

If I choose a C of 1000 uF, the ripple voltage is 8.3 V!  Do I really need to put more capacitance to lower the ripple voltage?  Is there another method of converting AC to DC?


texts: DS18B20 temperature sensor with Attiny25

texts:
I would like to make a simple thermal switch with attiny25 but first I need to read the temperature values from the ds18b20 sensor. I found some codes, here are the sources:
DS18B20 lib
UART lib

I need to use this uart implementation because the attiny25 does not have.
The UART function works well if I send characters but with the temperatures from the sensor it fails. I use the default 1MHz clock speed and 2400 baudrate.

I think the schematic is good, there is the 4,7kOhm pullup, and the data wire is connected. Vdd is 5V.

Could somebody help me please where to find the problem?
All of "my" code is here

Here is the onewire communication, is it good?

EDIT1:

Raised clock speed to 8Mhz, here is the 1Wire communication:

And the uart:

_delay_ms(1000) function is actually 0,9813s.
Is it possible, that the _delay_us() function is not very accurate so i got wrong timings?

EDIT2:

The reset condition was not enough, but that's not solved the problem.
Output of the onewire communication:


texts:
I'm currently working on a project where I need to be able to switch 7m of 9W/m LED strip (connected from both sides) using an Arduino with PWM. So the power of the led strip is about 63W at 12V. I have a plenty of IRF540N mosfets lying around but I need to calculate if I need a heatsink, or not. The intended circuit looks like this:

Note that I don't want the high current to flow on the tiny PCB traces, that's the purpose of the screw terminal.

I know that a logic level MOSFET would be better, but if I understand the datasheet correctly, IRF540N should be able to switch even much higher currents with 5V at the gate than I need. Or would using e.g. IRL540N make any difference?

Do I need a heatsink? If so, how to choose one properly? Is there anything else I should be worried of considering my circuit?
Thanks in advance!


texts: Classic control theory - Negative gain required for a finite velocity error?

texts:
I have an assignment to design a control system with 2 degrees of freedom (Prefilter + Controller) to control a plant with the following transfer function:

$$P(s)= \frac{2}{s(s-3)}$$
I am required to have \$K_v = 20\$

I do not need to add any integrator since the plant already has one (since i need a finite non zero error for a ramp input).

The gain required is: $$K_v=\lim_{s\rightarrow 0}sP(s)$$
I get a gain of \$K = -30\$, this is where I got confused since I'm used to get a positive gain.

Is this correct ? What is the meaning if a negative velocity error ?


texts:
I'm not used to working on Altium Designer(17.1). I couldnt find how can I export only pad layouts to making a stencil schematic.
It is good to export as a pdf file if it possible.


texts: Increase in compensation capacitor for op-amp

texts:
I am currently learning to design an op-amp, and understand that using compensation capacitors help to maintain stability of the op-amp.

Currently, my compensation capacitor has a value around 10 pf.
I would like to know what will happen if I increase this value to 30 pf, how is the gain bandwidth product affected?

Thank you.


texts: Some questions regarding impedance matching and tuning

texts:
For maximum power transfer in a circuit impedance matching is performed:

Similarly from the transmitter antenna to the receiver/load one can think the total impedance from antenna to the receiver as Za  and load impedance as Zl as below:

As far as I understand the aim is to make Zl as the conjugate of Za.

Now my questions are:

1-) How is Za known? Is there a standard value for Za so that we design Zl as the conjugate of Za?`

2-) Imagine we set the Zl as conjugate of Zl so we obtained max power transfer.  But imagine this is a radio receiver. Wouldn't the Zl change when we try to tune the reciver?


texts:
I am trying to get a GNSS module to communicate with a raspberry pi serially. I was attempting to set this up with an ESP module but I don't think it will work, or at least I am missing something. In the past I have used RPi break-out boards for GNSS with success. But this time I need to put the module on a PCB. The good thing about the breakout boards is that they don't require much additional circuitry, if any. But some of the PCB surface mount modules require lots of circuitry and I am trying to avoid this.
I think I've found a U-blox module that can be mounted to a PCB and then just connected to an antenna, ground, Vcc, and serial interface. Which is similar to the requirements of the breakout boards. The module is U-blox Max-8 datasheet
The datasheet mentions connections to an external crystal oscillator and RF in (antenna). I am sure there is some circuitry around the antenna, but I am not sure how to design this.  Also there is a time pulse output.
Below I attached the footprint and block diagram of the GNSS module. As I thought it might help.
Will my set-up be okay if I just connect Vcc, GND, antenna, and UART to the Pi?


texts: Can you determine RGB pinouts with a multi meter?

texts:
I have a Swiftech Apogee XL2 that has an addressable LED inside it. I want to connect it to my other RGB setups but I need to know the pin signals and voltage of the LED. I have a multi-meter at the moment but I can buy anything else that's needed. What do I need to do? Can anybody help? I only have very basic electrical knowledge but I'm ready to learn. I've included photos of the block and the connector in the link below. Thanks!

https://photos.app.goo.gl/wtKxNEYCA6qHwcP3A

Based on my research, I'm certain it's one of these two variations below. I'm just not sure about the voltage and how to identify the pin order.

https://rog.asus.com/forum/attachment.php?s=6ebdc99c23d18e50b41c1d879d3513ac&attachmentid=71018&d=1517278100&thumb=1


texts: Can someone identify this unmarked, brown, disc-shaped component?

texts:
I got a bag of these in a box lot of "amplifier parts" on eBay.  What are they?
The only measurement I can get with my meter is 10M ohms...


texts:
I have a customized inductor which is of E70 core. I would like to calculate the temperature rise in the inductor.
Ac copper loss= 5W, DC copper loss 2.5W, core loss 8W (according to steinmetz). I want to rougly calculate the temperature rise/operating temperature of the inductor. Is there any way to calculate it? Please let me know
https://www.tdk-electronics.tdk.com/inf/80/db/fer/e_70_33_32.pdf


texts: How to design filter for inverter for following cases?

texts:
I am going to make two pure sine inverters for collage project.

Both inverter uses 24V battery as DC voltage source. Switched to ~360Vdc and ~180Vd by boost converter accordingly.
Both then switched by IGBT full H-bridge circuit to SPWM AC. There is control circuit which has output od modulated sine wave(50Hz and 60Hz) with 20kHz carrier frequency. This controller drives the H-bridge.
At this point everything works perfectly fine as expected. But now to get a proper sine wave instead of a SPWM wave, i need to add filter circuit.
I am not sure how to design filter.

Some of suggestions i got from experts that you need a low-pass filter to filter the 20kHz. But dont know how to design one.

How to select L and C values? Is there any equations or calculation for this? Which topology should i use? Does hormonics removed completely by adding low-pass filter?

Case 1:
I/p voltage: 360 Vdc
Output voltage: 250 Vrms@50Hz
Output current: 5Amp max
Total power: ~1250VA max

Case 2:
I/p voltage: 180 Vdc
Output voltage: 120 Vrms@60Hz
Output current: 8Amp max
Total power: ~1000max

Thank you for help me. Please correct me if i am wrong and assume appropriate parameters/values if i missed to describe.


texts: Photodiode IC giving non-intuitive outputs

texts:
I am using a Photodiode IC (CXA2586M). This PDIC has multiple photodiodes but all of them have the same circuit. I have supplied voltages as per the datasheet (i.e Vcc = 5V, Vc = 1.5V) (See default circuit) . I am measuring voltages through an Arduino MEGA, so the reference voltage to the Arduino is Vc, just like how the datasheet says. When I operate the IC in these default settings, I get no output. But then I floated Vc (connection 8) and Vcc (connection 9) connections (and connect the Arduino GND to a power supply ground). When I shine some IR light on the PD, I get a voltage that is lesser than the voltage produced when there is no light. I first thought it must be because the output of the opamp is inverted and then added to Vc (=0?). If I connect Vc (connection 8) and Vcc (connection 9) to a common ground (with Arduino ground = common ground) I am getting the same results. Can someone explain why these three things are happening?
Default circuit:

EDIT 1:
The output of all 6 photodiodes (Ao, Bo, Co, Do, Eo and Fo) were taken after connecting arduino ground to common ground, just like @Circuitfantasist suggested, and is shown below.


texts:
I am trying to test a setup I made of a four point probe for some custom RF communication antennas I am making. I am testing our method of our design by measuring the sheet resistance of certain shapes on a PCB to optimize our system. On this board I have four shapes:

infilled square that's x by x dimensions,
thin line,
a square loop that is not infilled with a trace thickness and the rest is not filled, and
a triangle loop that has a trace thickness and the rest is not filled.

My question is

(a) how do I find the theoretical sheet resistance of the #3 (square loop) and #4 (triangle loop). I understand how to use the van der Pauw method to find the sheet resistance of shape #1 (infilled square) and the #2 (thin line) and the respective equations to find the theoretical sheet resistance.
(B) what would be the best method to measure the sheet resistance of my #4 triangle loop?

I want to make sure my theoretical method is accurate in A for the triangle, but I am not sure how with a four point probe. The thin line, infilled square, and the square loop are more intuitive.
Thank you for your answers in advance.


texts: Can I cascade voltage references to get better stability?

texts:
is it possible to get higher output voltage "stability" by cascading voltage references?

-- REPHRASING --

Suppose I have IC1 and IC2. Both are 0.5% accurate TL431 parts. IC1 takes 15V and outputs 12V. This is fed to IC2 and IC2 outputs 5V. Will the 5V output from IC2 be more stable, than if this output was directly taken from IC1?

Output current is well within the limit, and my main concern is line-regulation?

Thanks in advance,

Vishal


texts: Op-amp as an inverting amplifier with diode on OUT, circuit close to precision rectifier

texts:
I am wondering which kind of circuit is that and what is does when +-Vin is applied on the input. The output of the circuit is cathode of D26/R30/C52 node.
Thank you.


texts: Where can I find a list of PIC microcontrollers programmable and debuggable with a PICkit 2?

texts:
Where can I find a list of PIC microcontrollers that I can program and debug using a PICkit 2 in MPLAB X?

I am a hobbyist who would like to breadboard prototype a new project based on a PIC microcontroller. I'm selecting a PIC based on my needs, and would like it to be compatible with the PICkit 2 I already own. (I have previously used it with the dsPIC33 series).

I can't find any way to use the Microchip parts selector to filter by ICSP/PICkit revision compatibility.

I'm getting contradictory information from the datasheets. In the PICkit 2 readme, I'm told I can program and debug a PIC16F1938, but looking at the datasheet in section 32.0 I find that it is compatible with PICkit 3, with no mention of PICkit 2.

As the PICkit 2 is quite an old device and not receiving updates, should I assume that the readme contains the final list of devices supported by its most recent firmware? And that datasheets for any devices I find will refer to the most recent PICkit available at the time of writing?

The readme also contains the following warning

=================================================================
= NOTE: This list shows support for the PICkit 2 Programmer     =
= software application.  It does not show support for using the =
= PICkit 2 within MPLAB IDE.  For a list of MPLAB supported     =
= parts, see the MPLAB IDE PICkit 2 Readme.                     =
= (Typically in C:\Program Files\Microchip\MPLAB IDE\Readmes)   =
=================================================================

which I take to mean that I might be able to program certain devices, but not debug them. Is there a version of the 'MPLAB IDE PICkit 2 Readme' online?


texts: When does the capacitor charges and discharges in an astable multivibrator circuit?

texts: I was reading this and couldn't figure out at what point and how are the capacitors getting discharged?


texts: Measure both positive and negative voltages using ADC

texts:
I am looking into measuring both positive and negative voltages using ADC. My input voltage is in range from -55 to +55V, which is total of 110V. ADC I am using is MCP3424, since it is relatively easy to pair it with Raspberry Pi. MCP3423 is differential ADC with positive and negative inputs for each port. I am looking to connect negative(-) port to gnd, so I feed the voltage to the positive input. It gives me range from 0 to 2.048V. (readings of ADC are 18-bit)

I am looking to convert -55V to +55V range into 0 - 2.048V range. With some googling and my limited electronics knowledge I came into the following circuit:

simulate this circuit – Schematic created using CircuitLab

Questions/problems are:

would this work fine?
to which voltages I should connect op-amp voltage rails? OA1 to +5 and gnd, and OP2 to +55V and -55V? In that case, I would need high voltage op-amp, for example LTC6090?
do I need protection diodes at input or at output?

Are there any other issues I am not seeing?


texts: Can 2 amplifier support by 1 preamplifier?

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Can 2x 5v Digital Amplifier work with 1x 3.5-5v Audio Receiver Preamplifier without any risk? Can the Preamplifier chip burn out because of 2 amplifier connected to it? If the chip can burn out what can i do to prevent burning?
[![And here's the other actual photo of audio amplifier output][2]][2]
[2]: https://i.stack.imgur.com/m6d7I.jpg)


texts: Output Filter Components Breaking Class D Amplifier Chip

texts:
Hi I am designing a class D amplifier PCB using the TPA3122D2 amplifier chip. I am planning to base my circuit on the schematic from the evaluation board:

I bought components of the same values given in the schematic and tried building out the circuit on a breadboard. However I have run into a problem which I have isolated to the output filter circuit, shown here:

Before connecting the LOUT output pin the output filter I checked the LOUT pin with a scope and saw the high frequency modulated audio signal I would expect at a class D output. At this point the output circuit looked like this:

I then tried connecting the output to the output filter with no speaker attached, at which point the chip began overheating and the signal at the LOUT pin disappeared. After this the chip is fried, and overheats whenever it is given power. I was able to repeat this several times. At the point where the chip breaks the output circuit looks like this:

I also tried connecting the output filter to a fresh chip without the capacitor to ground, at which point the chip does not break:

At this point I am fairly certain the problem in my selection of either the L_FILTER or C_FILTER component, highlighted below:

The EVM board uses the following components:

Inductor: A7503AY-220M Datasheet (Not Commercially Available)

Capacitor: Capacitor, metal poly, 0.68µF, 63V, B32529C684J

When building out the circuit I used:

Inductor: DR0608-223L

I chose this inductor because it had the same DC current rating, and nearly the same maximum DC resistance (78mOhms vs 97mOhms).

Capacitor: 50V 0.68uf Ceramic

I used this capacitor because I had it on hand and was hoping to use SMT ceramic caps where possible for simplicity of fabrication.

In Conclusion:

Is there a necessary rating I am missing in one of these two components that is causing the amplifier chip to break in this way? What rating should I be looking at? How can I ensure I am selecting the proper components to make the circuit work?

I would like to understand this, because I don't want to use the components from the EVM. The inductor is not available on Mouser or DigiKey, and I would like to find a capacitor with a smaller footprint for my eventual PCB.

Couple Disclaimers:

I rechecked the circuit several times and am certain is built correctly on the breadboard. I am also aware that breadboards are non ideal for high frequency circuits, but I am only looking for proof of concept, not audiophile quality.

I have also acquired the EVM for this component and tested that the component works when given the proper circuitry.

I used a line level sine wave for testing the audio input. This problem occurs whether or not I give the amplifier any input.

Thanks!


texts: Switching power supply with battery and dynamo

texts: I am working on a little design project and will need to capability to have a switch that can change between powering some LEDs by Dynamo or Batteries. The batteries are not rechargeable and everything is rather low voltage. I have mocked up a circuit, but since I don't really have any idea what I am doing I would greatly appreciate if you kind people could tell me why this won't work. Something doesn't seem right with where it connects back to the negative ends of the power supplies after the LEDs.


texts:
I was reading StevenVH's response to the post How long will it take... and he brought up something I was completely unfamiliar with; the power loss associated with the large volt difference between the battery and the LED. His calculation was very straight forward.

My question is: where can I find more information on this? I have googled this topic and so far have come up with no other sources.


texts: Why would I use a thermistor instead of a LM35/36?

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Is there any advantage over the other in using a thermistor versus a temp sensor like a LM36 or LM35?

The only major difference I can see is that the LM35/36 have voltage limits of 5.5V and the thermistor is more of a really temp sensitive resistor that I could use with any voltage I want.  Maybe the temp ranges?

Is that about it?


texts:
simulate this circuit – Schematic created using CircuitLab

As you can see in the above circuit, I have converted AC to DC.

The transformer used in the above circuit is : If I apply 230V across the Primary, then I get 12V across the secondary coil of transformer.

Then I convert it to DC using 4 Diodes and a capacitor.

This DC voltage is applied to the coil of Relay.

This circuit works as expected.

Problem:

When I decrease the voltage on Primary coil of transformer.

Suppose I apply 200V to the Primary coil of transformer then also the chances are that Relay coil gets energized.

What I want:

If there is 12V or higher applied at the Red box in the diagram, then only the coil of relay should get energized else I should get 0V across the two terminals of relay coil.

I asked one of my friend about this problem. He said I should use a Zener diode in this circuit to achieve what I want. But I don't know where do I place the Zener?

Can anybody give me a suggestion?


texts: Cortex-M0 vs. Cortex-M0+ for an IoT sensor using LoRA

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Although I am an experienced software engineer, I am still quite a novice in electrical engineering.  So please bare with me in explaining my requirements:

I have a small garden in my backyard and I would like to add a soil moisture sensor in the ground, connecting it with an RFM95W as a LoRaWAN node.

The sensor will likely take a measurement every 6 to 9 hours, and go to sleep to save battery life.

Whichever board I use will connect to another RFM95W that's a LoraWAN gateway hooked up to an Rpi inside my home, so that I can forward the data to a local LoRa Server (MQTT).

Eventually I hope to get to a point where the board will open a water source when the soil is dry (over PWM motor control -- which I have done with the Pi over bare metal before).

Secondly I hope to run some very basic deep learning on the data, directly on the MCU as discussed in this blog post

Therefore, choosing an ARM MCU seems like a good fit.  There's the Cortex-M0 and its successor the M0+.

The problem I have in making the decision between them is based on the following:

1) The M0+ is marketed as a very power efficient MCU and therefore can work well with a battery for a long time

2) The M0 however seems to be very reasonably priced in its development boards, such as the SMT32F vs. the SAMD

Therefore I am wondering if the low power consumption is the case for the difference in price and if I can still get the same performance; i.e. long battery life, from the M0?


texts: I'm looking for a photosensor/photo IC part (combination of photodiode, linear amplifier, Schmitt trigger and output transistor) that can be powered with 3.3V. Fairchild QSE256/257/258/259 is almost exactly what I need, except that it requires 4-16 volts supply voltage and not working very stable at 3.3. I know that there is a number of parts usually used in the infrared receivers, but they contain demodulator (from 38KHz) which I don't need. Anyone here knows a good alternative to Fairchild part?