texts: SY8113 based Buck Converter Voltage Regulator design

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I am working on an Electronics design which incorporates DC-DC buck converter voltage regulators. This is the first time I've been working with buck converters, so I have no experience and only limited knowledge on their operation. I've already found a design using the SY8113 for the same purpose as what I'm designing (power for a RPi CM3), but when I use the formulas in the Datasheet, the Inductor value I get does not match the "reference" design I've used.

To explain a little bit further; The RPi CM3 pulls a max load of 250mA on the 3.3V (and 1.8V) supplies, which in turn are supplied by the SY8113 circuits. These supplies also power some peripherals, but the total current should not go beyond 500mA. However, using the Inductor value from the reference design (2.2uH), it seems the power supply circuit is designed for a 3A power draw.

So my first question is: What is the consequence of designing such a power supply circuit for 3A, and then only pulling 250 - 500 mA from it?

Secondly, if I calculate the Inductor value from the datasheet formula, I get a minimum inductor value of 11.22 uH (so 15 uH should be a usable value). However, finding a 15 uH inductor with a DCR below 50 mOhm (which is recommended in the datasheet) seems quite hard. So what is the consequence of picking a 15 uH inductor with a DCR of 98-115 mOhm for instance?

I would simply like to know if I should use the 2.2 uH inductor from the reference design, or if I should use the value I get from the datasheet formula. Also, I would like to know about any problems which could occurr from choosing an inductor with a slightly higer DCR than recommended.

Datasheet:
https://datasheet.lcsc.com/szlcsc/Silergy-Corp-SY8113BADC_C78989.pdf

Reference design:


texts: How to change the delay variable Td for a tline component in LTspice?

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I want to change the transmission delay-time Td (see picture) of a tline-component in LTspice as a function of time during simulation.
From my understanding, I cannot do that using the .step command, since that would generate individual simulations, each with a distinct value of the delay-variable {Td}.

Is the delay a variable that can be changed in time using a transient LTspice simulation?


texts: Snap-On impact driver Flyback Diode identification

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I have a Snap-On impact driver with a blown diode. I believe it's a flyback diode as it's on the output of the switch up to the motor.

I can make out several markings on the diode. C39 and C5, there is also an M or an N.

These markings don't make a lot of sense - I think some of the text is missing as the case is cracked and charred (see attached photo).

The impact driver uses 18V batteries and I think the trigger mechanism is rated for up to 25A. I've ordered some 1N4001's but I don't think these are going to be up to the job.

Trigger switch is a Marquardt 2701.6306.

What diode would you recommend I use?


texts:
I am building a NodeMCU controlled 12v solenoid. I am hoping to add an emergency backup battery supply, but the emergency backup supply should not power anything but the solenoid. In other words, if the SPDT switch is activated, the solenoid will always open (as long as the switch is active). I have the following circuit diagram:

The "DC Switching Module" referred to in the circuit diagram can be found here.

I have the following questions:

In researching other posts for this question, I found a lot of suggestions to use a relay as a backup power switching circuit instead of the DC switching module linked above. Is swapping out the module with a relay acceptable? What other features is that board providing? (note: I don't need the charging capacity of that board)
Assuming I use that power switching board, my original plan was to use an 8 cell AA battery holder to provide the 12v battery backup. The module states that when Vsource > Vbatt, it will attempt to charge the batteries. As the batteries get older and drop slightly below 12V, what are the repercussions of the module attempting to charge regular AA batteries? Is this something I have to be worried about?
As stated above, I don't want the battery backup to power the nodeMCU or any other electronics if the power goes out, only if the SPDT switch is activated. However, if the switch is activated, is it possible to then power the nodeMCU and "know" that the emergency system has been activated? In other words, if the power goes out, nothing should be powered. If the SPDT switch is activated, the solenoid should open, and the nodeMCU should power up and have an indication that the emergency batter pack was used. My initial idea was to step down the 12V from the battery to a digital in pin on the nodeMCU, but I don't know how to go about powering the nodeMCU only when the SPDT switch is active.


texts: "Given a condition, decide which execution should follow" with logic gates

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For the system above I need to give 'SR' an input from Hysteresis or Soft-Switching blocks. Whether SR should read one or the other depends entirely on the condition ISB >= 0.5*REF. To visualize it better, imagine a simple ramp function:

Then, if ISB is lower than 50% of that ramp, 'SR' output should receive
signals from Hysteresis block. On the other hand, if ISB is greater than 50% of ramp, Soft-Switching block should execute. In other words, it is like an if-conditional but in logic gates, if I'm not wrong.

If it helps, this is what is inside of Hysteresis and Soft-Switching blocks.


texts: Can I build a high-frequency SMPS choke out of an arbitrary coil of wire?

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Suppose I want to build a boost converter that runs at 100 kHz, with an input voltage of 600VDC and an input current of 100 amps. (This is hypothetical, I know the semiconductors involved would be exotic.) I'd need a pretty custom choke to do that; laminated steel probably won't handle that kind of frequency, and there's not much off-the-shelf to be had in this power and frequency range. So I'll build my own! What could possibly go wrong?

One possible way of building a choke to handle this is to use an air core. No core losses if there's no core! No component sourcing issues, less knowledge of magnetics required. The obvious down-sides are that I'll need many more turns of wire, more volume in my chassis, there will be higher resistive drop in the path... so maybe it's not a cost-effective approach. But let's assume it is for a moment.

So now I'm building an air-core choke out of something like 6AWG welding cable. Of course, skin effect will kill me, so I really need some sort of equivalent flat wire or heavy foil. The inductance calculations are straightforward, just a matter of turns and geometry. But what's going to happen when I actually try to run that in my hypothetical boost converter? Am I prone to insulation breakdown? Do I need to vacuum-impregnate the whole thing to with varnish to avoid that? Is there some other reliability problem with what I'm describing?

Basically I'm asking, what black magic am I prone to run into when running high currents, high voltages, and high frequencies?


texts: When can Self Resonance of a capacitor be a bad thing in bypass and decoupling applications?

texts: Specifically in decoupling and bypass applications, can the Self Resonance frequency cause problems (compared to ideal)?  If so, what kind of problems can it cause?


texts:
First of all, I'm a newbie regarding electronics&robotics so please bear with me.

I have been working as a programmer for a few years but I just got interested in playing with microcontrollers.

Can anyone recommend a book/tutorial for building a development board based on ATMEGA16-16PI
.

As of yesterday I own a breadboard and a atmega16 microcontroller.

Where do I go from here?

Thanks


texts: Do some soldered components use solder that only melts in temperatures higher than 480 °C?

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(solved - solution added at the bottom)

I have a power jack I can't remove. I tried a hot air gun set on 480 °C and a soldering iron set to 480 °C.

While some solder seemed to have melted on a few pins, the other pins
didn't seem to be affected. I tried applying flux, and I tried adding more solder with the hope the old solder would stick to the new one. I tried placing the soldering iron on each of these pins for 2 minutes and nothing helped.

Is it possible that some solder will not melt under 480 °C?

An image of the almost destroyed area:

My soldering iron photo added as requested in the comments

-----Solution-----

After reading all the answers i decided to try again.
i set both the soldering iron and the hot air gun to 480C.
this time, after reading about the Heat loss i tried removing
the tip of the hot air gun (shown in the photo)
and voila! it melts!.
I pushed each pin out slowly with the soldering iron
and the socket was successfully removed.


texts: STM32 microcontroller families and environment conditions (F4 vs G4 vs F7 vs H7)

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I want to refresh some product with old PIC18F and use STM32. New product requirement is 8 UART interfaces, a bit more DMIPS and more memory.
I probably could use STM32F0 or F1, some UART multiplexing or something like SC16IS752, but software and hardware would be more complicated and expensive.
I found that H7 and F7 microcontrollers have enough pins and I can map all pins for communication interfaces without any mess on PCB.
But I never worked with such fast microcontrollers. I can use powerful STM32H7 480MHz or 550MHz microcontroller and expect it to work like PIC18F in noisy environment? Or maybe I should choose something less complicated like STM32G4 or maybe **STM32F1" (and multiplex UART, or add SPI->UART converter).
My biggest concern is susceptibility for environment conditions:

work in the vicinity of high-power electrical devices like big contactors, circuit breakers
old inverters (which do not always meet today EMC standards)
LTE modem module on PCB
low cost wifi module on PCB

Questions:

are more complicated (like STM32F7) microcontrollers expected to be more susceptible to EMC than simple microcontrollers (like STM32F4)?

are more modern (G4 or H7 series) microcontrollers expected to be more susceptible to EMC than older microcontrollers (F series)?

shall I worry about microcontroller stability at all (in my case, which is migration from 8-bit PIC18F)?

(let's assume that board is correctly designed 4-layer board)


texts: Flashing MCU using JTAG ICE 3 / Avrdude / Beagle Bone Black

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I am in need of flashing ATmega1284P using Beagle Bone Black. I have JTAG ICE 3 connected via USB cable to Beagle Bone Black with Debian GNU/Linux 7 (wheezy). I have compiled version of Avrdude 6.1 which should support jtag ice 3 programmer. The problem is, when I run avrdude, it ends up with error message:

usbdev_open(): did not find any USB device "usb"

I guess avrdude can't recognize connected jtagice, but I can see it using lsusb command with result:

Bus 001 Device 002: ID 03eb:2140 Atmel Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Will be grateful for any advice.


texts: Is there a replacement for high voltage capacitors?

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Does anybody know if there is a replacement for tuning capacitors in an LC circuit that can support several kV (let's say 4kV)?

The LC tuning circuit is used as a load for a power amplifier. C varies between 30pF and 1nF, L is fixed, and the frequency range is 1-5MHz. The load is driven with 10us pulses with a period of 10ms, with a max. power of 200W.

The current tuning circuit uses vacuum variable capacitors and step motors to tune the capacitors and I would like to remove any moving parts.

I've been looking at varicap diodes, but these are for small voltages.


texts: I'm programming PIC with CCS. It's quite simple and functional. It's libraries are the best. Recently, I look for XC8 compiler, from Microchip. What are the advantages of using XC8 instead CCS?


texts:
Recently, I've been playing with arduino and programming games on an oscilloscope! I thought it would be really cool to recreate a classic vector screen (like the vectrex https://en.m.wikipedia.org/wiki/Vectrex) using lasers and perhaps mirrors.

Is this feasible and in what way would i tackle this? Should I use mirrors and motors? Are there motors fast and precise enough to direct the laser beam in a certain direction?


texts:
I recently got an XBee Pro Series 2.5 and another XBee Series 2.5 as listed here:

http://www.littlebirdelectronics.com/products/XBee-2mW-Series-2.5-Chip-Antenna.html
http://www.littlebirdelectronics.com/products/XBee-Pro-50mW-Series-2.5-U.FL-Connection.html

I then downloaded the latest version of X-CTU so that I could attempt to configure the XBees for use as a serial communication between two Arduinos.

When I launch X-CTU, the 'com test' works fine, and I see my modems with firmware version 1247 for both, and types 'XB24-B' and 'XBP24-B' for the normal and 'pro' XBees respectively.

However, here's the problem: when I click the 'Modem Configuration' tab, and then click 'Read', I am repeatedly told that "The modem configuration file was not found. Would you like to check the website for updates? (Recommended)" and then, on clicking 'Yes', "Modem configuration file not found after update".

The Digi people have weirdly fobbed me off with some comment about my hardware no longer being supported... but it's brand new stuff as far as I can tell. The Pro XBee says "Model:XBEEPRO2" and the regular XBee says "IC:4214-XBEE2".

Anyone got any suggestions?


texts: Sharing ground with high current circuit

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I'm designing an electrolysis machine controlled by an ESP8266 that also monitors the current and voltage of the electrodes with an INA226. There are two separates power supplies, 3.3V,1A power supply for ESP8266 and 7.5V,70A for the electrolysis machine. In order for the INA226 to measure the voltage of the electrodes it needs to share the same ground with the electrolysis machine.

simulate this circuit – Schematic created using CircuitLab

My question is will there be any issues sharing the same ground with the high current circuit? I understand that in theory it shouldn't be a problem but in a practical application will there be any negative effects such as leakage or noise cause by the high current. The ESP8266 is very sensitive and need a stable power supply.

My second question is will there be any difference in sharing the ground after or before the shunt? To measure the voltage of the electrodes ideally is to position the ground closer to the electrodes but that may cause a difference in the voltage between the two grounds.

PS: Both power supplies are SMPS that are powered by the same AC source.


texts: Sensing high differential voltages using operational amplifiers

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Is there any solution to sense high differential voltages using operational amplifiers (without using resistive voltage divider) ?

The input voltage range is [-30, 80] Volts.

I've searched on all operational amplifiers and no one fill this range.

I can't use a normal attenuator (Differential amplifier with gain < 1 ) since the common mode input voltage of the op amp is limited, and the input votlage has an independant ground ( I will not be sure if the CMIV will not be exceeded )

Thank you.


texts: Is the transistor Q4 in the wide swing cascode current mirror operating in linear region?

texts: In the wide swing cascode current mirror shown below, the transistor Q4 is in the linear region of operation according to the voltages at gate and drain. Is it not necessary for transistor to operate in saturation region? Is it ok to operate in linear region as I am not finding any issue?


texts: How to correctly calculate load on a DC motor

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What bothers me is the meaning of no load current (free current) which is the source of my problem.
I want my circuit's MCU to warn me if a motor exceeds 30% load. But how to calculate load?

There is a simple brushed DC motor characterized as below (made up characteristics).
Stall current: 1.5A
Free current (no load): 0.15A
Some load applied: 0.45A
Nominal voltage:  3V

Let's say I have a circuit consisting of nominal voltage source, a motor, some form of load and an MCU along with other necessary components allowing me to measure current flow.
What is the load if I measure 0.45A current?

I can think about two solutions:

1st solution related to stall current only:
Motor parts create some load which results in free current and in fact no load means 10% load.
    free current load: 0.15A / 1.5A = 0.1 -> 10% load
    applied load: 0.45A / 1.5A = 0.3 -> 30% load
therefore 100% load: 1.5A / 1.5A = 1 -> 100% load

2nd solution related to stall current and freerun current:
If it is described as no load then I subtract this current when calculating load and no load means 0% load.
    free load: (0.15A - Ifr) / (1.5A - Ifr) = 0A / 1.35A = 0 -> 0% load
    applied load: (0.45A - Ifr) / (1.5A - Ifr) = 0.3A / 1.35A = 0.22 -> 22% load
therefore 100% load: (1.5A - Ifr) / (1.5A - Ifr) = 1.35A / 1.35A = 1 -> 100% load
    where Ifr = 0.15A (freerun current)

When I use 1st solution rhen my firmware will generate warning at 0.45A current draw.
2nd solution will fire warning at 0.405A current draw

I have two questions:

1) Which solutoin is correct (if any)?
2) How to calculate load if I drive motor at 2V? (In relation to stall current equal 2V/3V * 1.5A = 1A?)


texts: Automatically disconnecting a F connector

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I have no electrical engineering experience.

I need to test a module, this module has what I believe to be a F-type RF connector to a device. I need to be able to disconnect that RF connector automatically.

Is there any kind of product or device that can be used to programmatically dis/re-connect a cable like this - some kind of terminal?

If not, how does automated hardware testing cope with requirements to physically disconnect devices?


texts: Performance of Parallel vs Serial speaker wiring

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Are there any sonic differences or performance characteristics of wiring speakers in serial vs parallel? I'm assuming in either instance one is properly loading the amplifier and has the choice of a parallel or series topology.

If there are any differences are they measurable via IR, FFT, RTA, etc?


texts:
I know little enough about electronics to have to ask basic questions :P

If I wanted to use a hall effect sensor as a toggle switch what is the minimal circuit that could be used?

Essentially want to put an LED into a badge and use a magnet to turn it on when near but stay on when the magnet is removed.  Then turn it off next time the magnet is near and leave it off.


texts: Do I need to remove the varistor from the circuit to check its validity with DMM?

texts:
When I looked up how to measure varistors, I found that the varistor's value should be 0L ohms (Over range, infinite resistance) when measured by a DMM set to test resistance, to indicate its validity.

When I tested the varistor (INR 14D681S) with my DMM (Set on resistance test mode), the result was 0.650 MOhms (Knowing that both its legs are attached to the PCB).

It's at the gate of receiving the VAC to protect the entire circuit (I point at it with red arrow.) One of its legs is connected to the ground terminal & the AC terminal, when the relay is engaged via a parallel connection with a capacitor (470n K275V~ 436D MKP X2,) the blue box above it.

There's no sign of burning or explosion on it as I saw in demo videos when it receives higher voltage than its value.

Do I need to detach one of the varistor's legs as regular resistors to get a right reading?

Do I need to detach it & test it with DMM if there's no visible sign of damage on it?


texts: Switching Power Supply - Type of MCB for Inrush Current

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it's regarding this PSU from Mean Well:

https://www.meanwell.com/Upload/PDF/LRS-350/LRS-350-SPEC.PDF

It has a 60A inrush current. My lighting circuit (1.5mm2 wiring) is tied to this PSU supplying 24VDC power to led strips.

My question is which type of MCB should i use for my lighting circuit?

Usually either B10 or C6 is standard here for lighting circuits but clearly it's not suitable here since the min trip current would be 30A x 1.4 = 42A which is well below 60A.

So i am considering C10 or D6, but are they normal for lighting circuits? D6 seems to be better since they have higher max Zs than C10. Here's a table from Hager showing the max circuit length for 1.5mm2 wire.

There's no data for D6 but i am assuming it would have more allowance than C10 which allows for 82m of run.

The max length of the circuit for this project is well below 20m so i assume either C10 or D6 should be alright?

Taking into consideration the circuit has quite a number of 5w GU10 LEDs (15 pcs, hence higher inrush), am i correct to assume that D6 (6x10x1.4 = 84A) is better than C10 (10x5x1.4 = 70A)?

I am just concerned with the use of type D because almost no one recommends it for domestic use so i was wondering if it would cause any problem.

Or given all the above, it wouldn't have mattered since the inrush current of the PSU may have happened too fast for the tripping to occur? The Mean Well documentation does not state how long it lasts but it seems to be 10ms: https://www.meanwelldirect.co.uk/glossary/what-is-inrush-current/.

Thanks.


texts:
The circuit takes 5V and will not consume more than 250mA. I have to use a reverse polarity protection diode, usually I use a 1N4001, but now I'm designing a PCB with all SMD components.

I have an LL4148 available. With this information, can someone tell me if it is safe to use LL4148 as a reverse polarity diode for a 1.25W circuit?


texts: Inductor in DC circuits and DC/DC converters

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Quick question which is somewhat confusing me.

So I understand that an inductor will have no effect in a DC circuit and merely acts as a resistor, as no change in current will be seen.

However for DC/DC converters does the principle of operation not involve an inductor, whereby the voltage can be stepped up across the inductor?

I am wondering how this can be the case if inductors do not effect DC  circuits?

Thanks


texts: What causes a UART device to continuously repeat its last transmission?

texts:
I just got this awesome Bluetooth module in the mail. I connected power and UART pins, and tied pin 34 to +3.3v with a 1k resistor (that puts the module into AT command mode rather than pass-through bluetooth mode).

So the first thing I notice is that it's sending "ERROR:(0)" repeatedly at about 15 messages per second. But if I send a character, it stops. If I have stopped it, then I can send an AT command such as "AT" followed by enter. The module proceeds to then send "OK" repeatedly at 15 messages per second.

I'm going through all the supported AT commands, and each one works, but it continuously repeats itself until I press the any key.

I tried connecting the CTS/RTS pins but it acts the same way as when I just use the UART pins alone.

I'm connected to my PC via USB FTDI UART cable that basically gives me a serial port on my PC (/dev/ttyUSB0) and a uart header on the other end, which I have connected the module to.

When I send the AT commands, I am getting valid responses, it's just that I have to press a key to stop it from sending its response over and over, and that key gets thrown away.

Seems really weird, but I bet there's a good explanation out there?


texts: How to reduce objects/hands impact on PCB antenna efficiency

texts:
I am trying to learn about planar inverted F antennas creation and have designed two different designs for two different frequencies with success.

One seems pretty much unaffected by the proximity of objects or even positively affected by a hand (-25dB return loss without anything, -20dB with objects, -30dB with hand) whilst sadly the other is hugely impacted (-30dB without anything, -5dB with objects, -10dB with hand). The major difference between the two is the width of the connection track to ground (4mm track width for the insensible, 16mm for the sensible).

Are "more ground loaded" antennas more sensitive to the environment?


texts: Use MAX680 charge pump positive side only?

texts:
I'm thinking of using a MAX680 charge pump IC to generate 10V from a 5V source, but I don't need the -10V output. The example here...

...shows four capacitors, presumably two for the +10V and two for the -10V. As I only require the +10V output, can I simply omit the other two capacitors?

(NOTE: I believe there is a slight error in the schematic. The lower-left capacitor should presumably connect to C2+ and C2-)


texts: Implementation of a logic circuit using NOR gates substituted for NAND ones

texts: My goal is to implement logic function F = XY + ZW. In previous board, It was constructed by using three NAND gates as brought in below photo. Yet, by employing NOR gates, I have to make use of eight gates. Is there any design employing less NOR gates?


texts:
I am trying to make a PCB with STM32 L412KB . Data sheet says it can use a crystal of 4 MHz - 48 MHz. But when I initialize the HSE under RCC option in Cubemx I get only one pin as RCC_CK_IN and no RCC_CK_OUT. However, LSE crystal highlights two pins.
Does it require special kind of oscillator or is there a bug or error in datasheet or software?
https://www.mouser.in/datasheet/2/389/dm00481909-1799148.pdf
edit: schematic image from nucleo board


texts:
I want to connect a 15 pin vga output from a computer to a TV input. However I do not want any data from the TV sent back to the computer. What I mean is that I do NOT want the TV to be a smart monitor but rather a dumb one. In other words the communication will be half duplex one way (from computer towards monitor ONLY).

I looked at the pin outs & I suspect pin 12 could be the problem as it is named bi-directional data. I am not sure if this is or this is NOT the ONLY problem pin. But just wondering.

Also I am not sure how a typical cable (15 pin) is connected. Of course I could open the connector and look inside but if you know the pinout diagram anyway, there is no need to do that.  I googled and it shows 15 pin several connections such as one for RGB or one for VGA and this is why I am not sure.

My dilemma is that this is a high security computer and if the computer detects any feedback from the monitor, because that info gets sent back to the server and I am screwed for security violation bigtime & I do not want to get written up or even fired LOL

Of course I can buy a dumb monitor but since I have two extra TV's I want to rather use them. These are just new digital TVs but not so new as these are not smart TVs like a WIFI-TV or roku TV or something.


texts:
I have a CdSe light sensitive resistor which goes from 0.1k to 30k light->dark .

It works fine outside the circuit. When I pass +/- 1V 400Hz AC across it, it seems to always have a low resistance. Is this to be expected?


texts:
Where to get a logic level diagram for a processor , preferably intel 4004.

i have block diagrams but want it to know more at logic level then transistor level.


texts: Is it relatively simple to design an ADC to ADAT interface with only a Toslink port?

texts:
For this project (I'm an experienced audio engineer but a relative beginner in electrical engineering) I really want to integrate a simple ADC to ADAT circuit in a patchbay I'm building so that I have 8 balanced TRS line inputs that I can patch into. No USB control needed, essentially the circuits that you find on any of the 8 channel preamps that have adat functionality added. If it's possible to get timecode off of the ADAT connection alone that would be great, something that works with interfaces like the Universal Audio Twins that only have an ADAT input is where I want to end up. I've looked into the Cool Audio ICs for the ADC and the ADAT generator, specifically the M8000 (https://www.coolaudio.com/features-page.php?product=M8000) and the V1401 (https://www.coolaudio.com/features-page.php?product=V1401), but I'm a bit lost on if I can successfully put them together in a straightforward and cost effective way. Again, very unexperienced in these matters but willing to learn and I'd like to think I have a general enough understanding to follow your answers. Any help would be much appreciated!
Also this seems to be a similar question but unsure if it squares up the same as mine V1401 ADAT transmitter and PCM4222 ADC


texts:
I would like to design a system where when my device is connected to a USB cable for charging, it should stop the device from functioning and charge the device. The device should be non-functional while connected to USB cable for charging. Also, I would like to transfer data over USB from the same device.
It is a battery-operated device and the USB class is USB CDC i.e. data transferred is not something that is previously stored somewhere e.g. SD card or some storage location.
How to make something similar work?
Turning Off the device can be easily done by taking input from VBUS and attaching interrupt on it and reading it on micro-controller.
There is a case where the device won't be able to know if the device is plugged in for charging or data transfer. I am thinking of something like starting a timer when an interrupt is generated on the USB cable and if no data transfer interrupts over USB is generated within some time, make a device non-functional.
Is there some different approach I can try?


texts: Common Cathode Laser Diode - Photovoltaic photodiode

texts:
I have a pretty quick question. I am working with a laser diode with an integrated photodiode. The pin configuration has a common cathode connection for bother the laser and photodiode. I want to power the laser diode but also operate the photodiode in photovoltaic mode as you get better response, however I am unsure if this is possible.

My example circuit is shown below, if I apply a voltage across the laser diode and then for sake of argument connect a resistor unto ground across the photodiode for a probe to measure the voltage induced from the photodiode current. Will the Current source, which is a lab supply with current limit, not provide an additional unaccounted for voltage across both the photodiode and resistor?

Is there a circuit setup that will allow me to operate the photodiode in photovoltaic mode without voltage/current being supplied to the laser diode affecting it?

simulate this circuit – Schematic created using CircuitLab


texts: Connecting a microcontrollers ground pin to a reference above ground

texts:
When I was at work the other day I was pulling apart an LED fault detection unit. I noticed they were using an Atmel ATtiny13A as the brains.

The interesting thing is this unit was multi-voltage and so they were connecting 9-33V to the microcontroller's Vin and then using a zenor diode to reduce the Vin by 5V then connecting the microcontroller's ground pin to Vin - 5V. Lastly they dissipated the remaining voltage with a resistor connected to ground.

The reason for them doing this was so it could interface Vin on its digital pins without any additional circuitry.

My question is, is this a normal thing to do (The microcontroller still had 5V between Vin and Ground pins)?

Is there some limiting factor stopping you from using the same logic and connecting the micro to 1000V at Vin and 995V at ground?

At what point does the voltage become too high to do this?

Is the only thing stopping this at higher voltages arcing out to other components etc

Thanks! :)

simulate this circuit – Schematic created using CircuitLab


texts: Finding the input impedance of this gyrator

texts:
I'm having a little trouble with this. I'm supposed to show that the input impedance of this gyrator is $$\frac{R^2}{Z}$$ but the math just isn't working out.

The gyrator consists of negative impedance devices (NIC, shown below) whose input impedance I found to be -Z. Am I right to assume that an NIC in parallel with a resistor would have an impedance of R-Z?

I was trying to solve this as a series of voltage dividers, with the last R and Z element having an impedance of $$\frac{Z}{R+Z}$$ This would be in parallel with the NIC and R pointing downward to give $$\frac{Z/(R+Z)+(R-Z)}{\frac{Z}{(R+Z)}(R-Z)}$$

And then this could be solved using the voltage divider equation $$\frac{Z_2}{Z_1+Z_2}$$ where $$Z_1 = R-Z$$ and Z_2 was stated above.

Unfortunately the math isn't working out to the desired answer, so I'm not sure whats going wrong here. Any help is appreciated.


texts: How to enable abbreviated port names in Atmel Studio?

texts: Good day! I have been working with Atmel Studio lately and am a bit confused about notation. Thus far, when I reference a pin, I usually just use the PORTxn notation (example: PORD0). However, I constantly come across code samples on the internet that employ an abbreviated form Pxn (PD0). I tried using this form because it seems very convenient but anytime I do it Atmel underlines it in red and throws an error, saying that it does not exist even though I have included the avr/io.h header in my file. Any ideas what might be going wrong? Here is my sample code. You can see the red underline for PD2. Thanks for the help!


texts: Can I download MPLAB IPE as a standalone app?

texts: I want to point someone to download MPLAB IPE without exposing them to the IDE.  Simple question, but I'm not finding a link on microchip's site.


texts:
My New term is going to start a couple of weeks from now. And as it goes in colleges here the first few months of the semester are easy. I have lots and lots of spare time to learn something new. I like to learn things by myself. But have not done much since a couple of months due to submissions and finals. I would like to dive into something exciting to learn this new semester.

My main interests are into uControllers, intelligence, analog electronics and robotic locomotion. Can you please recommend something which would take a few months to learn and would add to my engineering skills?

Regards.

Edit
My really lazy question has provided the community with a nice list of things to do once you have some knowledge under your belt. The problem is not with starting things, but continuing them. I faced that problem and also many before or after me. I propose we continue adding to this list. Here is a small summary of what I gathered.

Start with BEAM robotics: It has been a very facinating branch of robotics which uses only descreet electronic elements and it also has possiblity of adding intelligence using Nv Nets. But the problem is its still in its research phases and there are not many resources. I had to use the web archive to get to some papers and I dont think thats a very good sign.
Making your own PCBs: This is different and you wont get to learn this in class. So if you have to access to cheap PCB manufacturer I propose this to you.
Learn C: C is one of the oldest and most widespread languages and still used in industry
Learn ARM


texts: Arduino getting a bit of power after disconnecting supply

texts:
Alright, I pretty much just got into electronics, and one of my first projects was an Arduino-controlled LED light strip. I wrote some software to control the color and brightness from my computer via USB.

I simply connected a 12V power supply to the Arduino's VIN and GND pins, and also connected the 12V rail to the + connector on the RGB strip. I then drive the PWM signals to ground for R, G and B via MOSFETS.

This system is working perfectly, but I have encountered a very strange issue: If I unplug the 12V PSU completely, the Arduino turns off - to be expected. But if I plug it into my extension cord, which has a power switch, and I turn off said power switch, I would expect the result to be same - a turned off power strip does disconnect the line, right? And yet, every few seconds the Arduino's power LED blinks.

It seems to me, that some part of the system introduces a little bit of voltage, just enough to charge up a capacitor somewhere. I have tried disconnecting the USB cable, thinking that the power might come from there, but that did not change anything (the computer that the cable was connected to was turned off anyway, but I thought that maybe some power was still coming through it's USB ports).

I'm not too worried about power consumption or anything, but that red light blinking every minute or so is pretty annoying.. What can I do?

Thanks in advance,

Pi

PS: I just measured the voltage between VIN and GND when the PSU is plugged into the turned off extension cord, and I saw a voltage of about 2V, rapidly descending to 0, then a blink, and then it went back to 2V. That seems to confirm my theory, right? It doesn't help me to fix it though...

PPS: This is the extension cord I have: Amazon. Does it matter that is has USB ports? I'm not using these atm however.


texts: How do FPGAs reconfigure themselves based on the users wishes?

texts:
I've read the book "Code" and I love it's low level explanation for how cpus work.

Now I'm looking for a similar explanation for FPGAs.

The issue I can't wrap my mind around is: How does the FPGA change in it's connections between the logic gates?

I'm guessing bits get saved somewhere, which modifies which ones are connected.

But how does the VHDL/ verilog hardware language get pushed into the FPGA?


texts:
I want to determine a dynamic model (transfer function or state-space) of a non-ideal transimpedance amplifier to which is connected a photodiode at its input and a load (RC parallel).

simulate this circuit – Schematic created using CircuitLab

My approach to this was to first describe the circuit with the following equivalent circuit.

simulate this circuit

The op-amp open-loop behavior is modeled with a second order low-pass filter and a voltage-controlled voltage source.

My goal is to find the transfer function Vout/Iin, or a set of state-space equations that would completely described this circuit dynamics. I'm a bit confused whether or not I'm allowed to used superposition principle here because of the VCVS. This thread (Superposition principle: Dependent sources treated as independent sources) provides me a great deal of information on the subject but I'm still unsure if I can safely turn off the source. Based on the previous thread, I assumed it is allowed in my case because the controlling variable of the VCVS (Vin) is not turned off (instead, Iin is).

I first tried with equivalent impedances and superposition (turning off the current source, solving for Vout, turning off the VCVS, again solving for Vout and sum up the two results) but when plotting the Bode diagram on Matlab, the result was incorrect.

Then, I tried with the state-space approach but I simply didn't manage to get it work with 5 states (Vin, Vf (voltage accross feedback network) and Vout). I know that there is basically 5 energy storage components (Cin, Cf and CL and the two capacitors from the internal op-amp model) so I assumed 5 state for this circuit but maybe I'm wrong.

So my questions are:

Is my equivalent circuit a good starting point for my initial goal?
Am I allowed to used superposition as described above for both methods (transfer function and state-space)? If no, can someone please provides more details on why it is not allowed in my case?
Is my assumption on the number of state correct?


texts: Tuning current limitation for VCSEL laserdiode

texts:
Recently, we have bought a VCSEL laser diode, in which we can vary the wavelength by tuning the voltage and/or tuning current. Also, we got an application note in which it states as follows: "Set a current limit to 100 uA". I assume that this is a current limitation of wavelength tuning current.

However, How do I limit the current based on the pin diagram? Screenshots are given below.


texts: Can we connect Earth , Neutral and Digital Ground together in electronics system?

texts:
In our project has Digital Ground , Earth and Neutral.
As per the requirement Digital Ground and Earth ground tied through Bead inductor.

Is it advisable to connect Neutral with Chassis and Digital Ground ??

simulate this circuit – Schematic created using CircuitLab


texts: Why is the output of an inverting op amp limited by its supply voltage? I've always been wondering why is this so. I never found an exact reason for it. Also, if I have a +12 and -12 supply, why is the output below 24Vpp and not exactly 24Vpp?


texts: Beginners advice for process and tooling to make small PCBs

texts:
I've made a circuit that consists of many op amps and several other components. I soldered it on a simple PCB board but I'm worried about short circuits or physical damage when placed in a box.

Its size could also use some reduction since it's a portable application. I've never done PCB printing before so I have a lot to learn in this matter.

From what I understood, the available tools help you by printing the boards and you connect the parts afterwards by soldering them. Are there tools that will make the whole circuit with the components mounted? I've also read about SMD parts, do they normally come with the printed boards or do I have to order them separately?

Finally, they mentioned something about the thickness of the board, how do I decide on a certain thickness?

You can just point out the name of the tools and I'll do the research (I just don't know what to search for).


texts: Ceramic capacitors microphonic bandwidth

texts: I need to use some relatively high value (10uF) capacitors in a discrete switched capacitor circuit and I need them to precisely store their voltage for a small amount of time (about 5us). The alternatives are ceramic or film capacitors. The temperature is not a big problem as in that time there should not be a discernible variation, so I was thinking about using X5R or X7R ceramic capacitors. The main problem I found about ceramic caps is the microphonic effect. Is it negligible at such a frequency of operation or it is wiser to use film capacitors? They have to store down to few uV of voltage.


texts: Misunderstanding about flyback transformer and turn ratio

texts:
Here is the flyback that I m studying. It is a flyback transformer.

I am confused about the different turns ratio. If I suppose the input voltage minimum and so the duty cycle maximum (i.e D = 0.5), according to the relation which gives the output voltage in function of the input voltage, we should have :

$$\frac{Vin_{minimum}}{Vout+V_{forward}}\ = N$$

Nevertheless according to this formula I do not get the different turn ratio of the transformer.

For example by using my formula, the turn ratio between the 24V output voltage and the input voltage should be :

$$\frac{290}{25}\ = 11.6$$

Nevertheless, the turn ratio of the transformer is :

$$\frac{52}{4+3+3+6}\ = 3.25$$

It seems to be very different from my formula ... I do not understand :( Besides the duty cycle is regulated from the 24V. Any turn ratio corresponds to what I find with the formula ... I obviously miss something ...

Here is what I think the bottom coil section should be superior or equal to the one which follow it. Look the figure at the top of the pictures

Thank you very much


texts:
I want to switch (toggle) two devices using one GPIO pin and basic components. To achieve that I designed circuit containing one FET driving first device and two FET transistors for driving second device using inverter circuit. Design presented in attached picture:

I would like to figure out practical aspects about this circuit:

Is this correct solution for this simple problem? What can be improved?
Do I need resistors between GPIO and transistor gates? Or maybe pull down resistors for every gate? How will circuit behave when GPIO signal is floating (e.g. microcontroller boot time)?
What is the switching time between devices? Can I safely assume that only one device is always ON? Or maybe I should expect current spikes when devices are switching?


texts:
I am trying to run an RC oscillator using a 2n3904 the circuit looks like the following.

You can see the live circuit here. Simulation I want to run it at 0-5v but I am not getting the result, I assume because the voltage is not high enough?

What would you expect the minimum voltage requirement to be for this type of circuit.


texts: Is Current Transformer secondary current independent of load impedance? and How to find voltage of CT Secondary side?

texts:
i am trying to figure out a CT (Current Transformer) which is installed in my device of analysis. This CT has Two wires passing through its center hole (one is phase/red wire of single Phase AC supply and the other is neutral).

I don't know the specifications of it, because there is no marking over it (probably locally made) nor i have a datasheet or something.

So, i applied different values of ac current through it and noted down the current at secondary of this CT using Multi-meter's Ammeter Function. I came to know that, its turn ratio is Ns/Np = 0.01. It means for current flowing through one primary conductor is 10A, the secondary side output current of 0.1A.

The problems, i am facing are these;

1- When the current of 10A is passed through each pf primary conductors (phase and neutral passing through center), and the current is in same direction (in CT, direction of current is same in both conductors). The output secondary current is approx. zero. If the current is in opposite direction, the secondary current is 0.2A. How is this possible? In case of different direction, the resulting flux should cancel each other and no secondary current should be present and vice versa? But i am getting opposite behavior?? is there any possible internal structure that makes it work??

2- As far as i read about CT, their secondary current is independent on load impedance. It means if primary current is fixed, secondary should have been fixed no matter impedance of load is.right? But if is simulate this in Orcade PSPICE, changing the load impedance changes the value of secondary current although primary current source is fixed at some value.??

3- I know the secondary current based on primary current and turn ratio. But since CT;s are used to sense current, one actually sense the voltage at secondary of CT whose value is corresponding to primary current. But how do i know this secondary voltage at CT? Because at the output of CT, a bridge rectifier is attached and some RC circuit, so to find the ripple factors, values of ripple voltages, i need to know what voltage is appearing at secondary of CT. How do i find that??

Thanks in Advance..


texts:
I need some advice choosing a suitable SMD schottky diode for my PWM driven motor to handle back EMF. Normal operation of the motor is around 300mA with a start-up current of around 1.2 Amps. What key parameters within a data-sheet do I need to look for to suite my application.
Thanks


texts: Why is my current measuring with the DRV425 wrong?

texts:
I want to get the current through a conductor by measuring the magnetic field of a conductor by using a DRV425. I use the DRV425 Evaluation Board with the original settings (R1 = 100 Ohms) for my research purposes.
I use a 12 Ohms resistor and connect the resistor with the output of my signal generator. The signal generator generates a square signal with the following signal parameter:

High level: 5 V
Low level: 0 V
Frequency: 1 Hz

I use some tape to fix the wire on top of the DRV425. The thickness of the wire is around 2 mm, so the distance between the center of the wire and the chip is around 1 mm.

The green arrow indicates the flow direction of the current and the black line indicates the sensitivity axis of the sensor. Then angle of the wire and the sensitivity axis is around 90° (can´t rotate the green arrow that fine, so the angle of the arrow isn´t the same as the angle of the wire).
I also measure the output signal of the signal generator and the output voltage of the DRV425 with an oscilloscope.

As you can see from the screenshot I measure the following voltages with the sensor:

Low: 1.461V
High: 1.358 V

Now I calculate the H and B of the conductor with r = 1 mm during the high phase of the signal from the signal generator. For this I measure the current with a multi meter

Next I calculated the B with the equation from the DRV425 evaluation board manual:

I have to use the difference between the high and the low voltage of the signal for VOut, because I want to calculate the resulting field based on the current difference when I turn on the signal.
So my difference is

Which results in a B field of

So I have a difference of 10µT which I can not explain. Where is my mistake?.

Update:
Based on  the answer of Andy aka I replace the calculation of the current with a direct current measurement with a multi meter.
I also check the distance tolerance and it seems that the results are equal when I increase the distance by 0,5 mm. So a possible answer is that my distance measurement wasn´t exact enough and I haven´t consider the tolerances enough. So the next idea would be to use a thinner conductor to replace the thick (and flexible) isolation of the current silicone wire.


texts: AVR-HVPP with Arduino Mega2560 - Continously sending on SerialPort

texts:
I am trying to reprogram some scrambled ATtiny861A with the HVPP-version of ScratchMonkey.
I imported the sketch to my IDE (version 1.0.5) and compiled/uploaded that correctly.
With disabled debug-function, the TX-Led is lid continuously and some (much) data is transferred via serial port. Setting this to 115200 or 9600 baud didn't give any solution. All data is weird and there is no point to see what kind of data that could be.

So any ideas or suggestions on that, please?

PS: As I forgot to mention any detail, please ask, will give you all the info you need.


texts: IC on Digikey is 5x more expensive than board containing same IC on Alibaba: How?

texts:
I built a prototype using an NFC board I bought from Alibaba for 1$ (https://www.alibaba.com/showroom/rfid-rc522.html).

It claims to use the NXP MFRC522 IC, and if I look on the board the chip has that part number and even the little NXP logo. It works like a charm on the prototype so now I'd like to build the NFC antenna into the product and use the same chip (I'll go through the antenna tuning/matching process).

The problem is this: If I want to buy this IC on Digikey, it costs $5.36 for QTY 1 and $3.61 for QTY 1,500 (https://www.digikey.com/products/en/rf-if-and-rfid/rfid-rf-access-monitoring-ics/880?k=rc522). The whole board from Alibaba which comes assembled with other passives and a crystal oscillator, along with 2 NFC tags and some headers, is about 1$.

How can this be possible? Is this just a result of economies of scale (are they really making this many generic NFC boards?) or are the ICs definitely clones? I'd love to be able to use the IC only and make my own PCB antenna, but jumping from 1$ to even $3.61 has a very significant effect on the overall cost of the product.

Does anyone know what justifies this huge price difference and how to deal with it as an electronics designer trying to keep costs low? Any advice is appreciated.

[Edit]
Clarification: Although I'm using these particular boards as an example, the question I'm really asking is broader and (in my opinion) useful to others: Is it possible for designers to keep prices low when upgrading from cheap Alibaba-like proto boards to legitimate ICs from suppliers? And if so, what tricks/techniques can we use?


texts: High side current sensing for negative high voltage

texts:
I need to monitor the current for a negative high voltage supply.

I implemented the following circuit in a simulation program:

https://www.maximintegrated.com/en/app-notes/index.mvp/id/1867

But this only works when the high voltage is +1kV DC.
 Any ideas how I could make the circuit work for -1kV DC?


texts: How to connect a voltage and current source?

texts:
I'm currently trying to figure out a circuit design to connect a voltage source with a current source. More specifically, I have a power supply that has a safety current loop that is wired to an E-STOP button. I have a second supply used for a different part of my build, but that one has a voltage 5V safety loop. Is there anyway I could have both safety loops as part of one loop for the e-stop?
The thought process between connecting them is that the voltage safety loop currently has limit switches that need to also shut down the supply with the current safety loop


texts: Design Active Filter for audio (60hz-20Khz) with configurable gain, single power supply

texts:
I am trying to design an Active Band Pass filter, to pass frequencies 60Hz (220 v electricity noise) to 20K, part of ADC system.
My source signal is coming from Piezoelectric sensor, which means more than 100K ohm impedance, whith volatage levels between 100/200 mv p-p. i'd like to get output voltage of 1V p-p
I would like to build the buffer to 'translate' the impedance into a very low impedance.

limitation : 1 single 5v power supply.

I am using MCP6021/6022/6024 opamp , for the unity gain active filtering, and TI PGA2311  to apply the configurable gain.

I found in the MCP6021 datasheet a typical application in a ADC buffer,

and I tried to integrate this circuit with the PGA, So my current design absence that my negative voltage is getting cut (the source signal has no offset...)
So I need your help  in the following  problems :
1. how to create a DC bias?
2. how to improve the LPF ? i tried to simulate with CircuitLab and i get not the best graph...
2. how to add HPF to filter bellow 60hz?

This is the current design - lack of DC bias, and without the HPF for fc=60hz

Thanks a lot.


texts: Input impedance of instrumentation amplifier circuit

texts:
I am trying to understand the input impedance of this circuit, which is a part of the schematic of this project.

simulate this circuit – Schematic created using CircuitLab

The circuit explanation in the linked page says: "Note however that the input impedance is 100k resistance between the - input and ground, and 100k between the + input and the - input."

I don't understand why it is so. Does the sentence refer to the maximum impedance you have when the rotary switch is in position 4? If it were so, why aren't R6 and R7 taken into consideration for the calculation?
And why do R6 and R7 need to be precisely 49.9kOhm? What is the meaning of these two resistors?


texts: Verilog: sampling data in both posedge and negedge of the clock

texts:
I have a serial input stream which has left data in posedge of the clock, and right data in negedge of the clock.

I would like to synchronize and bring them to the posedge of the same clock.

I could do that using another clock with twice of the frequency.

How to synchronize the data using the same clock?


texts: Why transmission gates require two MOSFETs cant one MOSFET act as a switch?

texts:
A typical transmission gate is made of two complementary MOSFETs connected face to face. They basically act as switches cutting off or conducting depending on gate potential.

Then why cant we just use one MOSFET to achieve the same?


texts: How to create a current/load-dependent dc voltage source?

texts: I'm trying to supply a small device with 5V DC voltage, but for various reasons the power cable needs to be relatively long and therefore has considerable resistance. Predictably, the voltage drops under load by about 1V (i.e. when the device is active), which is undesirable. I tried simply boosting the supply voltage to 6V to compensate for this drop, but it appears that the device itself has some overvoltage protection and will simply not turn on at all in this case. I therefore think that I need a voltage source that increases its voltage in response to the output current. Unfortunately I have no clue how to go about doing something like this and would appreciate any help.


texts:
The motor operates within 140 rev/min to 600 rev/min. The controller gives an output in the range 4 to 20 mA. The sensor output reading equivalent to 400 rev/min, actual reading was 404 rev/min. The change in set angular velocity of the motor can be take as a step function. How to calculate Kp, Kd and Ki of this ?
  Error = 404 - 400
  Error = 4
  Kp = 140/4
  Kp = 35 Is it correct ? How to calculate other values Kd and Ki ?


texts: How to test analog component before mounting?

texts:
I have been in a small factory today, they produced 4 kind of PCBs that all are simple analog boards, each month they produce 1000 of them. The problem is that till now, after mounting them almost 10% of them were damaged. So they prefer not to test each of them, as the cost of time did not worth for them. But now the percentage of damaged has increased and they are looking for a solution. I suggested to add some test point to the PCB and I will design a Tester. But the problem is something else, they say that they don't need a module tester. They need some thing that can tell them if they have to buy a series of component or not , for example they order 10,000 of capacitor , they need a tester to test specific number (I also have to suggest the number ) the capacitors and tell whether or not buy these batch or not , so basically I need to design a tester that can test these things : Resistors , Capacitors , Different kind of Diodes , Relays and LEDs?

So the questions are mainly these 2 thing :

For each device what are the best way that I can test them , even a document would be useful but , tips here is really appreciated because I can ask questions about.
Do we have to test all them before mounting or not?!! how can I get the efficient number for testing to get the best result?
(if I have to change the question topic just let me know please)


texts: The question is whether DTR pin of FT232RL becomes active only if the chip is plugged into PC USB host where drivers are installed or whenever the chip is powered on by VCC pin? I couldn't find any particular information on this from datasheet.


texts: Reducing Undershoot and Overshoot in a custom voltage regulator?

texts:
I'm trying to build a voltage regulator that takes in a reference voltage and an unregulated voltage (to power the components, and this voltage is always greater than the reference voltage) and outputs the reference voltage over any capacitive, inductive or resistive loads.

Here's what I have so far:

The circuit has to be capable of outputting up to 5A at 6 volts and should have a relatively fast slew rate even at a high capacitive load (nearly 200 V/ms over 4uF load). It also has to have good load regulation (output voltage shouldn't drop over 200 mV at max load in reference to the reference voltage).

To satisfy these requirements, I've added a darlington pair since the 2N3445 is definitely capable of outputting that power, but requires a large base current, which the LM358 can't provide.

The issue I have right now is that when I attach a current source that emulates a 1 Amp load on and off at 1000 Hz, the overshoot and undershoot errors I'm getting are terrible. The output voltage jumps up to nearly 10V above the reference voltage for about 50us before crashing down to near 8V below the reference voltage before finally coming to rest at the reference. Is there anyway I can modify my circuit so this error is fixed?

I tried attaching a larger capacitance to the output (I have a 1 uF right now, this is the design capacitance, and not a load capacitance), but that didn't help out too much. Also attaching a larger capacitance over the smaller transistor's emitter (where the 2uF is hanging right now) destroys the slew rate (I crash down to nearly 8 V/ms when I hang a 22 uF there.)


texts:
Has anyone seen a Micro-USB socket which installs with the socket perpendicular to the PCB?

You'd think that this would be readily available as a standard option but it seems to be hard to come by. We have a situation where use of such a connector would be significantly beneficial.


texts: Can I use MCU's internal oscillator when communicating with GPS and cellular modules? I want to avoid connecting external crystals for the MCU since they generate noise, extra components, extra costs, and on top of that require PCB design constrains and cautions. My MCU is stm32L4


texts:
I bought the following 1 ch relay - Link (433 MHz), which is just like the one in this video - Link.

I want to connect it to my room lightbulb which uses 220v, the thing is I'm not sure how to wire it as you need to connect it with plus and minus.

As far as I'm aware 220v is AC, which means there's no really plus and minus, how do I wire it then? It just doesn't matter? Or is there something else?..

Not really sure about anything I wrote, so take it easy in case I'm wrong, thanks for the help. :]


texts: LED module design considerations for an aluminium board

texts:
I need to design a LED module something similar to below.

Could anyone who is experience tell me if there is any SW (or tools) to determine how to place the LEDs to have a good and evenly distributed light output, and a SW to simulate the thermal behavior and decide how far they should be replaced from each others? If there is no SW for it, what are the thumb of rules to determine distances of the LEDs from each others (especially if all are not the same color LEDs)?

Second question, I have never done any design than FR4 board. What are the standards on aluminum boards (aluminium thickness, copper thickness, solder finish, etc). What Gerber files do I need to send to a factory (top layer, top silkscreen, holes, top solder paste, anything else)?

What are the considerations while preparing such module?
Obviously all should be routed in a single layer. Is it good to have a ground layer for the unused area or is it better to etch and have aluminium to have a better thermal performance?

Do you have any suggested reference/document/application note to read to design LED module on aluminium board?


texts: Does the nfc ring work with this rfid reader?

texts:
Is the NFC ring compatible with RFID Reader ID-20LA (125 kHz) ? In this stackoverflow question it is saying there are standards, but I cant find out weather the 2 products support any of those standards.

edit: in the faq of the ring i found out it supports ISO14443.


texts: Maximum current supply tolerable by 1A Motor driver IC

texts:
I'm using this particular motor driver IC to supply bi-directional current to a magnetic torque rod. I intend to control the Input A & B pins with my arduino uno, by using the PWM pins and varying the duty cycle. I also powered the IC with my arduino board and obviously got laughed at by my friends, I didn't know that arduino uno boards could only supply a maximum of around 200mA of current. So I'd like to ask:

I am planning to power the IC with a DC power supply this time, I
plan to give it a Vcc of 5V, how much source current should I supply
to this IC?
On the datasheet, I am not sure what the Sa and Sb (pins 1 and 4)
    pins are, the datasheet says they are driver output returns, but I
    have no idea what that means.

Thanks!


texts: Solar panel: temperature coefficient of Pmax

texts:
I am trying to determine the best solar panel for my needs so I've been looking at the datasheets. But I've noticed that some of the datasheets are lacking the temperature coefficient of Pmax.

Is there a way to calculate this by using the temperature coefficient of Voc and the temperature coefficient of Isc?


texts: When I search online for buying diodes, I find much more zener-diodes than normal diodes. Is there a reason for this? Can you use every zener-diode as a normal diode or is it uncommon to use diodes in circuits and some other circuit is used to replace the stuff you usually would do with a diode?


texts: I need to sense if a rope has been touched, what is a safe way to do this?

texts:
I was thinking of attaching a sensor to the rope but there are so many types I'm not sure which one to use.

Pizeoelectric, rolling ball, vibration, tilt and tension sensors could all work.

I need the lowest cost, most durable solution. Anyone have any ideas here?


texts: What causes that characteristic chirping noise in switching power supplies?

texts:
Every now and then a switching power supply like the ones from mobile phones, laptops, etc. makes this very characteristic chirping noise.
What component in there causes that noise, and why?


texts: Reason behind Altera's divide functions pipeline delay?

texts:
In Quartus II, the standard lpm_divide function has a parameter PIPELINE_DELAY. The default value is floor(WIDTH_Q div 2) - where WIDTH_Q := width of the quotient in bits.

I'm curious why this is a parameter there for the user to change (rather than just being whatever it is), and I can't quite see why this default value is the case.


texts:
I am new in instrumentation and control. I am developing a hardware for a project and the following is my application.

I have three phase stepped down voltages and stepped down currents entering my board.
I can adjust the loads to be either purely real power loads or reactive power loads.
I am trying to calculate the three phase rms voltage, three phase frequency using pll, real power, reactive power and the apparent power.

I am able to calculate the real power, reactive power and apparent with ease. I am having some questions regarding the three phase rms voltage calculation. Right now, I am measuring the line to neutral of the phase A and calculating the rms of this measurement. The loads are balanced and the system is also balanced. I would like to know, if this is the right way to calculate the three phase rms (just the rms of one phase) or is there any other way to calculate the three phase rms.

Any help would be appreciated.


texts: What power are you measuring after a PWM Switch for a DC Motor?

texts:
simulate this circuit – Schematic created using CircuitLab
If you are using PWM for a brushed motor and you place a power meter after the switch without any time-gating (it just measures continuously all the time), are you measuring any coherent singular power? Or is it just an incoherent mashup of power from the supply and the free-wheeling energy stored in the coil's magnetic field?
EDIT: Actually, the free wheeling power subtracts from the supply power so...what is that?


texts: I have just made up a adjustable regulator circuit using the LM 317T, the input is approx 33 V, and output 16 V, but the LM 317T when cold regulates at 16 V, but once the LM 317T gets very hot the voltage drops to around 13 V, and is not regulating, my load is drawing approx 150 mA, can anyone please advise.


texts: Why is CVD not used in the manufacture of NMOS gate oxides?

texts:
I know that chemical vapor deposition (CVD) is a vacuum deposition method used to produce high-quality, high-performance solid materials. The process is often used in the manufacture of semiconductors to produce thin films, there are several CVD methods, such as LPCVD, PECVD etc.
These methods can be used to deposit a thin film on the substrate controllable with process parameters such as temperature, pressure, and precursor gases.
My question
Why is CVD not used to deposit gate oxides in the manufacture of NMOS devices?
I can't find the reasons and the main causes.


texts: Help understanding table in SAM E54 Datasheet

texts:
I apologize if this isn't the right place to ask this question, but I'm having trouble interpreting a table in the SAM E54 datasheet.

I am trying to configure the size of the SmartEEPROM on an SAME54 Xplained board. The example project from Atmel Start states:

/* This example assumes SBLK = 1 and PSZ = 3, thus total size is 4096 bytes */

So I looked in the datasheet which says, the SmartEEPROM interface maximum size depends on SEESTAT.PSZ and SEESTAT.SBLK:

I can't figure out which column corresponds to which configuration bit. It would seem the column on the left is SEESTAT.PSZ, but then it wouldn't make sense for SEESTAT.SBLK to be 3 according to the chart.

Any insight is greatly appreciated.


texts: Alternative On/Off Toggle momentary button and Raspberry

texts:
Hello. I found this system with Alternating ON/OFF Switch that I want to use it with a momentary button to turn on/off a led. It's working with IC 4069 Hex Inverter on 12V. The question is how can I change the state of the system(On or Off) in parallel with the momentary button, using Raspberry Gpio output pin?

Thank you,
Razvan (hobbyist)


texts: What is the difference between SOT 23 and SOT 23-3 package types?

texts:
I am faced with two types of packaging:

SOT 23
SOT 23-3

Is there some difference between them?

Based an article in Wikipedia it seems like there are no differences.


texts: Eliminating the resistance variable in the total resistance/reactance equation of a series RLC circuit

texts:
Assuming that we have a simplified equation from a simple series RLC circuit where the total resistance/reactance in the series RLC circuit is equal to 100 times the resistance R:

How do we modify the equation in such a way that we can eliminate the R^2 on the LHS of the equation? An online source gives me an explanation in this form:

My question is, what is the reason behind taking the LHS of the equation within the square root and equating its inductance and capacitance variables as greater than the resistance variable? How is this exactly implied?


texts: ATmega328P development board not working

texts:
I've made a development board for ATmega328P like Arduino Uno.

Fig. 1 - schematic

Fig. 2 - bottom layer

Fig. 3 - top layer

I am able to upload the code using FTDI chip (I've used the chip which has boot loader in it). However the code is not working; I mean the LED connected to pin 14 is not blinking.
When I check the supply voltage at pin 7 I get 4.9 V, but when I check the same at GPIO it is giving 0.3 V.
I'm new to PCB designing. Please let me know what could have gone wrong.
void setup() {
   pinMode(14, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
    digitalWrite(14, HIGH);   // turn the LED on (HIGH is the voltage level)
    delay(1000);              // wait for a second
    digitalWrite(14, LOW);    // turn the LED off by making the voltage LOW
    delay(1000);              // wait for a second
}


texts:
I built an audio baseboard for an i.mx6 board built by embeddedarm(ts4900).  I used the ubiquitous sgtl5000 codec from freescale.  While the end result works ok, I find that the output from the line out is noisy, with noise starting about -55db from peak.  I feel like this is a codec misconfiguration or obscure layout issue, but its not clear to me.

Link to amplified audio file, note the quiet white noise when pcm dac is set to 0.

If I set the pcm dac output to zero, the noise drops to normal white noise.  This would make me suspect the codec rather than my analog stage.

Per linux sgtl5000.c mods, I see it is not using the internal charge pump, which is right.

I also have done testing with the riotboard which has the same processor and codec, and find similar results, although the noise is about 5-10db less.  One difference is that they have powered vdda with 2.5v.

Green is analog ground, brown ground, purple -12v, orange +12v

R41 is not placed.


texts: How is data allocated in an assembly language using the instruction set?

texts:
Consider the following excerpt of assembly code written for the Nios II embedded processor architecture:

    .section .data
    .align 2
va:   .long 0x0
vb:   .long 0x11223344
vc:   .long 0x55667788

The following needs to be done:

Allocate enough memory for all three variables
Ensure the memory allocated is contiguous
Translate instructions that use a variable's name into instructions that use the variable's address

I don't see how this can be done through the instruction set and was hoping for some insight on how the translation of the code above to the instruction set occurs.


texts: 24-bit DAC + D-class amplifier in singlechip - good solution for pocket MP3 player?

texts:
I am doing personal project - portable MP3 player.
Goals are sound quality + power efficiency. Price is not limited to a reasonable amount (100-200$ in parts is ok)

Will single-chip DAC+D-class amplifiers give me best possible power efficiency while having excellent audio quality? I've seen 24-bit ones but a little overpowered (like 1.5W per channel). This looks very juicy - No need to design analog part, all sensetive parts are inside the chip. Are there any pitfalls with this approach or with D-class amplifiers with headphones in general?

I afraid that classic op-amp based or AB-class amplifiers will eat too much power + I will need careful design of analog part after DAC.

For example: http://www.cirrus.com/en/products/cs43l22.html
Separate output for headphones scares me.

Design targets:

32-50 Ohm headphones support @100mW
LiIon power supply, the more play
hours I get the better :-)
Maximum
quality (as long as I can hear the
difference)
I have 24-bit decoder
output, so going down to 16 is
possible to not that fun (extra
analog filtering and noise shaping).


texts:
I have an assignment on AM modulation.

I implemented a circuit and the output wasn't exactly correct, the output is not symmetrical about the x-axis.

I'll post screenshots which might explain the situation better.


texts: Output voltage of boost converter in shutdown mode (no switching)

texts:
Is it common that a boost DCDC converter has an output voltage which is the same as the input voltage, when the switching does not occur?

I'm reading the TPS55340EVM-017 datasheet. In the caption for Figure 14, it is described that the EN voltage goes low and the output voltage ramps from 24 V to Vin. I'm curious why the output voltage does not decrease to zero.

Also when the switching does not happen, isn't there limitation in the output current?


texts: TPS54383 switching regulator components.

texts:
I'm trying to build a switching regulator using the TPS54383 dual output regulator, Now I've got most of the components and schematic figured out here.

pdf

Except the inductor's and diode; I'm running one output at 12V with a possible draw of 3A and the other at 5V with a maximum draw of 500mA. What value's should I be looking at when ordering a diode and inductor?


texts: Why is the PMOS in NAND gate in Parallel and NMOS Series?

texts: Why is the PMOS in Parallel, and the NMOS is in series?


texts: PIC12F1822 program counter jumping around during debug and release programming

texts:
I am having the most awful trouble getting things up and running with my PIC12F1822.

I'm using MPLAB 8.86, an ICD3 and have the chip, in a DIP package set up in a breadboard on my desk. As far as I can see, the connections are all reliable and okay. Things were working okay until yesterday evening and I've not moved/touched anything.

The schematic looks like this:

Before I write any code which does any input based on switches or gets data from serial, I just want to twiddle some LEDs so I know everything is working.

Here's my code :

 list           p=12F1822      ; list directive to define processor
     #include <p12F1822.inc> ; processor specific variable definitions
     __CONFIG _CONFIG1, _FOSC_INTOSC & _WDTE_OFF & _PWRTE_OFF & _MCLRE_ON & _CP_OFF & _CPD_OFF & _BOREN_OFF & _CLKOUTEN_OFF & _IESO_OFF & _FCMEN_OFF
     __CONFIG _CONFIG2, _WRT_OFF & _PLLEN_OFF & _STVREN_OFF & _BORV_19 & _LVP_OFF

 #DEFINE        LED1    PORTA,.2        ;Status LED connected to Port A bit 1

 D1      EQU    0x7D    ;temp register, used during delay
 D2      EQU    0x7E     ;temp register, used during delay
 D3      EQU    0x7F
         ORG     0x0000            ; processor reset vector
         GOTO    START
 ;----------------------------------------------------------------------------;
 ;DELAY ROUTINE, FORCES THE PIC TO WASTE TIME FOR 0.1Seconds AT 16MHz;
 DELAY
         MOVLW  0X35
         MOVWF  D1
         MOVLW  0XE0
         MOVWF  D2
         MOVLW  0X01
         MOVWF  D3
 DELAY_0
         DECFSZ D1, F
         GOTO   $+2
         DECFSZ D2, F
         GOTO   $+2
         DECFSZ D3, F
         GOTO   DELAY_0
 ;4 CYCLES
         GOTO   $+1
         GOTO   $+1
 ;4 CYCLES (INCLUDING CALL)
         RETURN

 ;------------------------------------------
 START
         ;DEVICE CONFIG STUFF
         BANKSEL        TRISA
         MOVLW  B'00000000'     ;EVERYTHING ELSE IS OUTPUT
         MOVWF  TRISA
         BANKSEL        OSCCON
         MOVLW  B'01111010'     ;PLL DISABLED, 16MHZ CLOCK SPEED, INTERNAL CLOCK
         MOVWF  OSCCON
         BANKSEL        ANSELA
         CLRF   ANSELA          ;ALL PINS AS DIGITAL
         BANKSEL        ADCON1
         MOVLW  B'00001111'
         MOVWF  ADCON1          ;ALSO TURNS OFF ANALOG THINGS
         BANKSEL        CM1CON0 CLRF    CM1CON0         ;ALL COMPARATORS OFF
         BANKSEL        PORTA
         CLRF   PORTA           ;CLEAR EVERYTHING ON PORT A BEFORE WE START, EXIT WITH BANK0 SELECTED
 LOOP
         ;BLINK THAT LED LIKE YOUR LIFE DEPENDED ON IT
         BCF    LED1
         CALL   DELAY
         BSF    LED1
         CALL   DELAY
         GOTO   LOOP
         END

Nothing too exciting.

When I make this and then program it in in release mode I just get one LED stuck on.

When I make this in debug mode and then try to step through with the debugger/ICD3/MPLAB - I can't reliably get the code to run.

Specifically, the program counter seems to be jumping around all over the place.

To my understanding, when you reset the MCU using the yellow button in MPLAB, the program should go to the top and then wait for you to either run or step through - like this:

The location of the PC is indicated by the green arrow - mine keeps showing up in places which are not the start! It shows up in all manner of places e.g.

This makes debugging a pain - and - indicates that something is really wrong.

I have no idea what - has anyone else come across anything like this?

It isn't limited to this code snippet either. In [This Example] after a reset the PC jumps in at BANKSEL OSCCON (line 138) and when running seems get get stuck inside AUXHELLOWORLD (i.e. the LED keeps flashing forever).

Any insight you might have would be most appreciated
Best
D


texts: PCB components identification and reference designators?

texts:
This is a motor controller for evaporative air cooler. I'm new to electronics so I'm trying to understand this chip upside down. But I have a problem with these components.
1. Q2 , I think it's transistor but I'm not sure.
2. EC3 (ss 100 16v) i think it's an oscillator but who knows.
3. EC4 battery?
4. REC1 no idea what it could be.
5. The IC f8234. I looked for the datasheet online but couldn't find anything.
and I would like to know if it's possible to draw the schematic from the pcb for more understanding of the controller.


texts: Remote control led has 3 volt power source output I need it to switch on a 12 volt power source to power led array

texts:
I have a LED candle that runs on  two AA batteries which total 3 V.  It already has remote.  I want that 3 V output to turn on a 12 V battery supply to a LED array.

I am trying to use an NPN transistor for this: am I doing right? What else can I use?


texts: Opto-isolator/ optocoupler for electric isolation in IC design

texts:
I came across while reading the opto-isolator technique used for electric isolation in embedded systems/ Integrated Circuits design that " Opto-isolator is not recommended for electric isolation in power applications IC's mainly due to it's dV/dt sensitivity". So I would like to know:
1)How dV/dt sensitivity affects isolation?
2)Is dV/dt sensitivity the only reason to avoid optocoupler especially in power application IC/embedded systems?
3)Are there other limitations in optocoupler which compel one to chose other isolation techniques?
Looking forward to your suggestions and guidance. Thanks.


texts:
I'm looking at a schematic where various wires connect to blocks.
Sometimes the blocks have a wishbone symbol with a number next to it.
Other times, it's a wishbone symbol without a number.

I've been unable to find the correct name for this symbol to learn more about it.
What does it mean?

Possibly unrelated, but why do the above blocks have dotted lines, while the one below does not?


texts:
my doubt

TXP,TXN of phy chip is connecting to P1 and P3 of the connector.
I thought it must connect to P4 and P6 of the connector.

Can somebody please let me know which is correct point 1 or 2 ?


texts: is it possible to protect workstation by removing VCC connection from workstation to circuit?

texts:
I am a newbie to electronics and currently working on my very first electronics project on Atmega16.I want to make sure that no matter how high current is supplied(by mistake), it shouldn't damage my laptop.So here's what I did till now,

I haven't soldered barrel jack near voltage regulator.
Here I connected MISO, MOSI, RESET and SCK from the connector to IC as shown in the image.

I was warned that if the voltage regulator doesn't work as intended and large current enters the circuit it will not only damage my circuit but also laptop's port and fry the motherboard.
So, in theory, I thought if I don't connect VCC coming from my laptop to USBASP then my laptop should be safe.
So my question is,
1)is it a good idea to not connect VCC from the computer and completely be dependent on an external source for power?
2)if yes then will I face some issues while programming the device as I am not supplying the VCC from a computer?
3)Also is it ok to disconnect ground from the laptop also?

I am not well with designing tools like eagle or ORCAD so here is the hand-drawn circuit diagram,

Also here is the back of the board.I want to remove the white and brown wire which are ground and VCC to ensure the safety of my laptop.
Is it a good idea?
And sorry for terrible soldering.It was my very first soldering experience.

I know this is not a discussion forum but still, if anyone finds a mistake in the circuit and if this platform permits such discussion then I will be pleased to hear it as I can correct them and avoid such mistakes in future.
If not then please ignore this part and let me know in comments I will remove this from question.

Thank you,


texts: What is the danger of going beyond the current limits of a wire carrying AC current

texts:
If I am using 18 AWG wires with a current limit of 16 A,
what are the potential hazards of going beyond 120V,AC and 16A,AC(rms)?


texts: Why is it better to ramp a stepper motor than not?

texts:
I have been working with a stepper motor, to which I made a controller which  drives the stepper motor using a trapezoidal speed ramp.

It logically makes sense that it would be hard to stepper motor to start at a target speed without accelerating up to it, but i am currently looking for some literature that also states that doing this is also makes sense.

I need some literature that confirms my theory, which i cant find anywhere, or anything that well explains the benefits of doing it so?,and what you gain.

I was prior to my project advised to look at it, which is why i didn't try to just give it a simple PWM signal.

Maybe asking my questions rather than literature is a better idea.

Why is stepper motor benefiting from ramping, I mean DC motor can easily start a certain speed?

If you choose to microstep you stepper-motor, wouldn't it be redundant to use a speed ramp?  there would not be "that far of a distance" between the coils, which would only suffer for the torque...?


texts: Smoothing Accelerometer/Gyroscope Displacement Tracking for Mouse Motion

texts:
I'm working on a project to combine a linear acceleration reading from an accelerometer and gyroscope, adjusted for gravity, into displacement/position on an x-y plane, specifically for turning the motion of the sensor into mouse motion. I have a basic implementation working, but the movement feels very noisy and unnatural.

Essentially I'm following the "double integration" method. I've done some research and am familiar with some of the limits to overall accuracy of this approach, but its been my impression that people are talking about this in the context of dead-reckoning for navigation, so I was hoping we could get a "good enough" solution for mouse movement feels relatively natural. Especially since at some level if its being used to register mouse movement there'll be a feedback loop from the user controlling the mouse.

One of the biggest problems is that I haven't found a satisfactory way to remove noise that doesn't degrade the overall feel of the motion too much. I've tried Kalman filters, but have only gotten it working via external libraries such as Kalman.js given the complexity of the math behind it. So it could've partly been down to not having the right parameters for the filter. However I've also read that a Kalman filter may be a bad choice for smoothing mouse movements since its hard to model the underlying system of a person moving a mouse around to interact with a computer.

Is there a different filtering technique we could apply to smooth the movement readings out? Or is producing a reasonable short lived estimate of displacement, even for this application of producing mouse movements, ultimately too difficult with just an inexpensive accelerometer/gyro?


texts: PSpice transient analysis failed to converge

texts:
I have the following schematic with 2 opamp. I have to do a transient analysis and eventually find the slew rate of the opamp. My simulation parameters are:

Run to time: 1ms
Step size: 1us

Any suggestions on how to fix it ?


texts: Trouble understanding why multimeter gives different resistance readings

texts:
I want to preface this by I am a hobby electronics guy with some experience from reading The Art of Electronics. I know how to use a multimeter but I am very confused at what I am seeing.
I am using a marginally more expensive Circuit Specialists multimeter and testing the resistance across a set of fuel injectors I am working on. My procedure to test is as follows:

Set multimeter to Ohms (200)
Measure resistance across the male side plugs

I was looking for a reference range of 10-14 ohms and I got 15.3 ohms. Concerning. So out of curiosity I measured again:

Set the mulimeter to Kilohms (2k ohms)
Measure the resistance across the male side plugs.

However this time I got 0.012! So 12 ohms, right in the middle of the range.
It may be as simple as my multimeter just isn't very high quality but I was hoping there was a better explanation. Having one measurement outside spec, and one inside spec really bothers me.
EDIT:
My multimeter model is #MT-5211
https://www.circuitspecialists.com/3-1-2-digital-lcr-multimeter.html


texts: Single-line power transmission of 1MW over 35,000km

texts:
This question posted on the physics stack exchange has not received much attention. I thought the audience here might be more able to answer it.

Background

A space elevator is mechanism to provide enormously lower cost access to orbit / space. While sounding fantastical, apparently there is real discussion and current investment in trying to develop some of the necessary technology for such a device.

The advantage of the device is that it avoids "the tyranny of the rocket equation". To achieve this though, it must be possible to send power to climbers ascending the elevator, rather than have them carry their own power source.

Energy and power requirements.

Assuming a climber of 2 tons, wanting to achieve geostationary orbit at 35,000 km, the total energy to be delivered is 2,000 kg * 9.8 ms^-2 * 35,000,000 m ~ 700 GJ (I'm using uniform g, making this an overestimate).

If the climb takes 7 days (approximately 200 km per hour), then the power requirement for the climber is about 1 MW.

Current favoured solutions to this transmission are to use lasers to shine power to the climber, which would receive the power using photovoltaic panels. Here's an example.

Question

A likely candidate material for the tether is graphene, which is an excellent conductor.

Given this, can "single-line" power transmission provide 1MW of power continuously over 35,000 km without adding undue bulk to the line or receiver?

Notes on possible answers

The answer: "No, this would almost certainly be highly impractical because …" would be an excellent answer.

Some suggested points that an answer might address, and which might make the approach impractical:

Radiative loss from the tether.
Shape constraints on the tether to make it suitable for power transmission.
Mass constraints on the tether due to insulation requirements.
Mass constraints on the climber for receiver equipment.


texts: What happens with Arduino digital pin 12 when the power is OFF

texts:
I am using the Arudino Uno board as a trigger/delay pulse generator to drive a laser. I read the input pulse train sequence from a test point on the external device using pin 12 set as INPUT. The Arduino and the external device share the same ground.

Now, when the power is on, everything works fine. But when I power off the Arduino board, it seems that pin 12 starts to distort the signal on the test point of the external device which wrecks up the device's normal operation. This only happens when the Arduino is grounded. When I power On the Arduino or disconnect its ground from the common ground, the external device works fine again. As a result, I cannot have the Arduino connected to the device when it is powered off.

If I check the resistance between pin 12 and the ground, it is infinite when the power is ON and about 16MOhm when it is OFF.

Does anyone have an explanation/cure for that?


texts: what happen IF condition is executing and interrupt is came?

texts:
suppose i have condition if( a & b).
during execution if it execute A variable after that interrupt is occur.
so is it complete the if condition means till B variable and after that go for that interrupt or is it stop executing till a variable and after complete interrupt it back to B variable??


texts:
I was recently confused on where the resistor would go on the circuit. I then learned that it didn't matter. Is there a standardized sequence for the placement of resistors? For example,

battery -> resistor -> led

or

battery -> led -> resistor

I know it doesn't make a difference, I just want to know which one is more common. Thanks!


texts: Isolation of voltmeter via DC->AC->DC conversion

texts:
I bought a combination ammeter/voltmeter which has the restriction that the measurement/display circuitry must be powered from a different source than the measured voltage.

What is the underlying cause of this restriction (if there is a general underlying cause)?

More specifically, if I power this unit from an AC->DC wall-wart where the AC comes from a DC->AC inverter powered on the DC side from the same voltage source that I'm measuring, will this provide sufficient isolation for the unit to work?


texts: How to write to 93LC46B EEPROM from an Arduino using SPI

texts:
I have a question regarding eeproms and an Arduino (I am using Arduino Uno). I have the following eeprom: 93LC46B. From the datasheet I understand that in order to write the integers 1 and 2 to the first address I need to send the following bits:

1 : starting bit
01 : write opcode
000000 : first address
00110001 : 1
00110010 : 2

The result is 1010000000011000100110010

I have the following code but I can't seem to find out how to send the bits, can anyone help?

#include "SPI.h"
int ss=10;

void setup()
{
  pinMode(ss, OUTPUT);
  digitalWrite(ss, LOW);
  SPI.begin();
  SPI.setBitOrder(MSBFIRST);

  digitalWrite(ss, HIGH);
  //what to send?
  digitalWrite(ss, LOW);
}

So I updated my code but I still can't get a desired output.
This is the code:

#define DATAOUT 11//MOSI
#define DATAIN  12//MISO
#define SPICLOCK  13//sck
#define SLAVESELECT 10//ss

//opcodes
#define READ  0x80
#define WRITE 0x40

byte eeprom_output_data;
byte clr;

void setup()
{
  Serial.begin(9600);

  pinMode(DATAOUT, OUTPUT);
  pinMode(DATAIN, INPUT);
  pinMode(SPICLOCK, OUTPUT);
  pinMode(SLAVESELECT, OUTPUT);
  digitalWrite(SLAVESELECT, LOW); //disable device

  SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0);
  clr=SPSR;
  clr=SPDR;
  delay(10);

  digitalWrite(SLAVESELECT, HIGH);
  digitalWrite(DATAOUT, HIGH);
  digitalWrite(SPICLOCK, HIGH);
  delay(1);
  digitalWrite(SPICLOCK, LOW);

  spi_transfer(WRITE); //01000000
  spi_transfer(0x10);
  spi_transfer(0x11);

  digitalWrite(SLAVESELECT,LOW); //release chip
  delay(3000);

  eeprom_output_data = read_eeprom();
  Serial.print(eeprom_output_data,DEC);
  Serial.print('\n');
  delay(500); //pause for readability
}

char spi_transfer(volatile char data)
{
  SPDR = data;                    // Start the transmission
  while (!(SPSR & (1<<SPIF)))     // Wait the end of the transmission
  {
  };
  return SPDR;                    // return the received byte
}

byte read_eeprom()
{
  //READ EEPROM
  int data;

  digitalWrite(SLAVESELECT, HIGH);
  digitalWrite(DATAOUT, HIGH);
  digitalWrite(SPICLOCK, HIGH);
  delay(1);
  digitalWrite(SPICLOCK, LOW);

  spi_transfer(READ); //transmit read opcode
  data = spi_transfer(0xFF); //get data byte
  digitalWrite(SLAVESELECT, LOW); //release chip, signal end transfer
  return data;
}

void loop()
{
}


texts: What should be the Winding at Primary and Secondary in Transformer?

texts:
I am trying to build this circuit and testing it in Multisim. As you can See this circuit Produces between 12V-14VDC with 10A but the transformer used in this, I am not been able to get it's Primary and secondary Windings. I have tried Adjusting it in Multisim and tried formula Np/Ns = Vp/Vs.

Can anyone Please tell me How to Find correct Windings? Or what are the Windings? And Please can anyone Tell me What's the Meaning of 24A at Bridge Rectifier? And that F1~1A & F1~10A.

How to make this type of transformer in Multisim and Achieve that 24A Bridge Rectifier?

I have Added Multisim Circuit Diagram That I have Found And Done Some Change. Because Original one was not able to draw More Current. So is this One. I don't where is Problem I want Output of 3A Constant But it is drawing 1.194A Only. Please Help Regarding It.


texts: I'm ultimately trying to make a BLDC motor driver, but in the meantime I'm trying to get the IRS2301 MOSFET driver I intend to use working as expected. I built an H-bridge test circuit with a 1K resistor as my simulated load (shown below), and started with both drivers' HIN and LIN pins grounded, when I do this, the gate and source on both high side FETs read 10V, but are not shorted when do a connectivity test. The low side gates read 0V, as expected, but I cannot seem to get the high side gates to operate correctly with the driver. I've modeled my circuit based on AN-978, and cannot figure out why even the most basic operation isn't working, so any advice would be appreciated.


texts: is there any problem with these via-pads?

texts:
I'm designing a footprint . in this pictures we have vias and pads and i want to know is there any problem with that? i mean I've heard somewhere that something like this is a technology named via-in-pad and it is not much recommended because of some reason.
i just want holes with certain radius and pads for them.


texts:
I am trying to compiling the javacv in the beaglebone black. During compiling the javacpp-present. It shows the error

sorry, unimplemented: Thumb-1 hard-float VFP ABI

Here is the command I am using for the compile

mvn clean install  -DskipTests -Dplatform.name=linux-arm -Dplatform.compiler=arm-linux-gnueabihf-gcc

And the entire message about the error:

[INFO] /usr/bin/arm-linux-gnueabihf-g++-4.8 -I/media/card/javacpp-presets/opencv/cppbuild/linux-arm/include/ -I/usr/lib/jvm/java-7-openjdk-armhf/include -I/usr/lib/jvm/java-7-openjdk-armhf/include/linux /media/card/javacpp-presets/opencv/target/classes/org/bytedeco/javacpp/jniopencv_calib3d.cpp -march=armv5te -Wl,-rpath,$ORIGIN/ -Wall -O3 -fPIC -shared -s -o /media/card/javacpp-presets/opencv/target/classes/org/bytedeco/javacpp/linux-arm/libjniopencv_calib3d.so -L/media/card/javacpp-presets/opencv/cppbuild/linux-arm/lib/ -Wl,-rpath,/media/card/javacpp-presets/opencv/cppbuild/linux-arm/lib/ -lopencv_calib3d -lopencv_features2d -lopencv_ml -lopencv_flann -lopencv_highgui -lopencv_videoio -lopencv_imgcodecs -lopencv_imgproc -lopencv_core
In file included from /usr/include/stdio.h:934:0,
             from /usr/lib/jvm/java-7-openjdk-armhf/include/jni.h:39,
             from /media/card/javacpp-presets/opencv/target/classes/org/bytedeco/javacpp/jniopencv_calib3d.cpp:26:
/usr/include/arm-linux-gnueabihf/bits/stdio.h: In function ‘int getchar()’:
/usr/include/arm-linux-gnueabihf/bits/stdio.h:44:14: sorry, unimplemented: Thumb-1 hard-float VFP ABI
getchar (void)

Anyhow, the command about the g++ seems correct, but I have no idea why the error occurs.


texts: How long can a Resistance Heating wire last until it cannot be used anymore?

texts:
First time posting so hopefully this makes some sense!

I want to heat up a 28 gauge Nichrome wire to around 1,800-2,000 degrees Fahrenheit for short bursts at a time (about 5 seconds long). I'm curious as to how many "short bursts" I could do until the Nichrome wire wasn't usable anymore.

I know Nichrome can be used in electronic cigarettes, and for the extreme users, those coils can last about 2 weeks of consistent use (~100 puffs/day so 1,400 total uses). But from my understanding, their lifespan is only that long because the taste starts to go bad. Not because the wire is no longer heating up. If that is true, I'm wondering how long can a resistance wire last under those circumstances?

Another question I have is that I know electronic cigarettes reach a much lower temperature than 2,000 degrees Fahrenheit (around 500-600 degrees Fahrenheit) so would higher temperatures significantly reduce the life span of the wire? Or is it somewhat negligible?


texts: differential amplifier ac equivalent circuit

texts:
In figure a, \$R_E\$ is clearly in series with the base emitter reisistance \$r_e'\$ of \$Q_2\$.
But in figure b, why are they putting \$r_e'\$ in parallel with \$R_E\$?


texts: When looking at consumer electronic devices with batteries I sometimes see the battery capacity listed in Wh (watt hours) and sometimes in mAh (milliamp hours).  I would like to be able to compare the two different metrics and I'm wondering how to convert from one value to the other.


texts: ARM Cortex-M Floating Point Multiply-Accumulate Cycle Time

texts:
According to the ARM Cortex M4 technical manual, a floating point multiply accumulate instruction (VMLA.F32) takes 3 cycles. However the separate multiply (VMUL.F32) and add (VADD.F32) instructions only take 1 cycle each. This would suggest that a multiple accumulate instruction is slower than just doing the two operations separately which seems rather strange.
Is this really the case, or am I overlooking something here?
The only reason I can think is that they included VMLA.F32 for compatibility reasons, but in that case, why is it not possibly to complete the instruction in two cycles?