texts: PCB Etching (Negative Photoresist) Issue

texts:
I seem to be having issues getting my new PCB etching setup to work.

My earlier setup worked just fine which included:

printing negative artwork on a parchment paper
exposing a copper pcb with negative photoresist film on it through this negative under a regular table lamp
treating this with Sodium Carbonate, Ferric Chloride and finally with Sodium Hydroxide (in order)

This produced acceptable results (I was able to go down to 10 mil trace width). However it took a long time as I was exposing with a regular table lamp (around 50 mins per side).

So to get more consistent and finer results, and to speed up the process, I decided to make the following changes:

use laminator to attach the negative photo resist film to the pcb instead of using a hot iron
use an UV lamp for exposure

used 2mm transparent acrylic sheet to sandwich the pcb between the artwork (instead of glass). Mainly because I broke the glass and had acrylic sheet lying around

Needless to say, the new method did not work as I expected. The issues that cropped up:

The pcb after exposure seems underdeveloped. The white areas in the artwork (where copper should not be etched away) should be dark blue after exposure. However as seen, that is not the case. They seem to have virtually no change in color at all.

The tracks are fuzzy. I think that's because of acrylic sheet bending on the edges when clamped. So that's not a big deal. Can be solved by using glass. (there is a prominent displacement of tracks in the picture because I took the pcb midway and then exposed it again without thus causing misalignment)

If I go ahead and rinse this is a solution of Sodium Carbonate, I don't see unexposed photoresist (under the black area of the artwork rinse off), again pointing to under development as the cause.

I am not sure what could be the issue here. Is it because the acrylic sheet is blocking uv rays thus causing pcbnot to be developed properly or is my uv unit to too weak. I has 4 bulbs, each 9W

Would appreciate any guidance here.

Update:

Picture of result using a drop of oil to hold the artwork and skipping the acrylic sheets


texts: How to ensure your MCU can't be reverse engineered?

texts: I am building a project around an nRF51822 chip from Nordic, using the mbed prototyping platform. I would like to ensure that the code cannot be extracted / deduced from the project after it has been programmed and released. Is there anything I can do, cryptographically or otherwise to make this possible?


texts: How can I reconstruct exported oscilloscope data?

texts:
I want to reconstruct oscilloscope data imported into a spreadsheet directly from my Velleman PCSU200 oscilloscope.

The data of primary interest are the frequency and amplitude, I'm not interested in any other data.

The information in the spreadsheet looks as per the image (snippet) below: (the resulting data is 4000+ rows so too large to post here - I can make it available for download if required.

My question is, how can I calculate the frequency and amplitude from the given data?
The amplitude setting on the scope will always be fixed for the purpose of these measurements if that helps, however the timebase will vary.

EDIT: I have added a revised image of the Spreadsheet capture. Additionally, I have added a screenshot of the 'scope display.
As can be seen, a 1kHz waveform is being displayed.

EDIT2 I will only be using pure sine waves.

The spreadsheet data can be downloaded here. (it's plain text file with a .txt extension, so will simply render in your web browser)


texts: What voltage are AGM battery capacity ratings supposed to be computed at?

texts:
I have an AGM battery that is rated at 12V 225Ah. Using the 50% "rule", the battery should be able to deliver 12 * 225 * 0.5 = 1350 watt hours = 1.35 KWh.  However, when the battery is under load, the voltage drops to as low as 10.5V, where many power inverters are set to warn the user.  I don't know what the average voltage is during a capacity test, but it slowly drops from as high as 13V (with a very light load at the beginning of the test), to around 10.5V if the load is just right such that it is heavy enough to dip the battery that much at the tail end of the load test.

So my question is, do battery manufacturers expect us to use the nominal voltage when calculating the usable capacity of that battery or the average voltage during the capacity test?  I don't want to overestimate this 50% rated capacity (100% usable capacity) and overdischarge my battery.  The difference is about 6.25% if I use the average voltage (around 11.25V) vs. the rated voltage (12V).  For example, 11.25V (ave) * 225Ah * 50% = 1.265 KWh, not the 1.35 KWh we calculated using the 12V rating.  Which is more correct?  is it more correct to just use the watt hour rating by the manufacturer and not worry about voltage sag under load, as that is already accounted for by the different capacity ratings such as 10 hour, 20 hour... drain rates?


texts: High Power, Low Freq MOSFET H Bridge Design

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I would like to replace an Hbridge circuit that has 2 SPDT relays with MOSFETs.

The design parameters are as follows:

VBUS - 13VDC nom (12min 14max)
Icont - 50A
IPeak - 75A (intermittent still 3 mins so basically its still cont)
75A max On 5mins Off 3 mins

The circuit is controlled by manual operation that will operate a brushed DC motor FWD and REV. There is no uC and no PWM.

I have been looking at various MOSFET datasheets and have not been able to find any that would allow me to run VBUS into the Gate and have VDS just pass the current through.

I was looking at the Safe Forward Operating Area graphs and it seems like with almost any of the MOSFETs that a VDS of ~12VDC puts me extremely low on the available current allowed on avg ~10A.

For example
http://www.vishay.com/docs/71903/sum85n03.pdf

On the safe operating area of the graph for a VDS of ~12VDC the ID would be ~8A if I am reading it correctly. Since there is no Micro I need to use DC values.

I can Change Vgs with a Voltage Divider but I cant change VDS. The only thing I can think of is to use parallel MOSFETs.

Any suggestions would be of help.


texts:
Possible Duplicate:
  Books about pic18f?

I'm looking for good book for a beginner that would explain basic things about PIC microcontrollers, MPLAB IDE and MPLAB C compiler and programming in C.

I have decent, but basic knowledge of digital electronics. I already know how to write programs in C, so I just need some kind of fast transition to C language for embedded systems. It would be great if book includes examples.


texts: What does the value of reactive power represent physically?

texts:
In my power engineering course, we were introduced to reactive power. I believe I understand what reactive power is in essence: there is energy transfer between the source and inductor/capacitor. This makes sense to me, and I can do many calculations just fine. However, I am failing to understand what the value of reactive power represents. From my notes:

$$\begin{align*} P=VI\cos\psi      \\
               Q=VI\sin\psi
\end{align*}$$
where P and Q are active and reactive power respectively. I understand the formula for P, and its derivation is presented in my notes. Physically, P represents the amount of energy dissipated through the resistor. What does Q represent?

Considering the graphs of power vs time in capacitor/inductor only circuits, the average power is 0. Shouldn't this mean that on average reactive power is just 0?

Apologies if the question is a bit unclear, I am having a difficult time just explaining my confusion.


texts:
I'm building (on a breadboard) a 16Mhz oscillator (part of another circuit) with the HEF4060B using an external xtal.

Schematic I'm using is

that's not so different from the example on the HEF4060B datasheet

I've powered it (12V) and mistery started.

The first problem is with the 16Mhz xtal the thing doesn't even start to oscillate. But that's a secondary problem. If I replace 16MHz xtal with a 11MHz one (or less) the oscillator starts.
I can see with the 'scope that I have a nice 11Mhz sinusoidal waveform on the pin 11, and I see a not-so-nice square-ish waveform on the pin 9 (so, I imagine that oscillator parts works fine). The MR pin (Master Reset) is connected to GND. So, everything should work as expected. Problem is that I have fixed values on the output pins! The 14 stage counter is receiving a signal from the oscillator stage (as I can see it on the pin 9) but doesn't count. Pins are almost always zero. And when some pin is at 1, if I raise MR, pin goes to 0. So, the logic and Master Reset is working, but the counter is not.

Already tried:

*Changing supply (from 5 to 15V)

*Power the circuit from a 12V PB cell (to filter out supply problems)

*Replaced the 4060 (more than once)

*Replaced Xtal (more than once)

*Replaced every passive component (more than once)

I'm really puzzled. It must be a problem so silly that's too evident for me to see!!

(HEF6040B datasheet)

UPDATE:
I've rebuilt the circuit with a different layout on a different breadboard, and now it works with 4MHz, 11MHz and 14.1MHz (from 9 to 15V). The 16Mhz one still have some problem, because it starts to oscillate only if I remove the capacitor between PIN11 and ground. I tried with some random values, from 1 to 1000pF, and nothing. But I think that this could be a problem caused by the breadboard as apalopohapa said. Moreover I don't have the datasheet for the specific xtal, so I don't know how to find right capacitor values. Maybe this should be another question...


texts:
I cannot understand how this current limiting circuit works.

Image source: UNLV Physics Department, Bill O'Donnell, Current Limiter Circuit

Here is where I get confused:
When Q2 is turned on, the voltage at the base of Q1 becomes close to 0 and Q1 stops conducting current. Therefore VR1 should be 0, which will turn off Q2 and turn on Q1. What am I missing here? If we put an emitter resistor for Q2, shouldn't that solve my issue?


texts: What is the maximum length of xlr cable from a Canon XA10 to a microphone without losing quality of sound

texts: What is the maximum length of XLR cable from a Canon XA10 to a microphone (say a Rode NTG-2, using phantom power) without losing quality of sound.


texts: I can’t seem to understand the preference of the flyback converters for the reason given below

texts: Why would a flyback design normally have large energy storage components than an equivalent forward converter design but flyback converters are still preferred for low power designs requiring multiple isolated outputs?


texts: How to get the maximum luminance out of a LED?

texts:
What is the formula to obtain the resistor value I should use to drive a LED to its maximum luminance for a given input voltage?

And for the maximum power effectiveness (luminance / watt)?


texts:
Right now I have ported an application from LPC2478 to Cortex M3  (LPC1788) and things are working fine at 120MHz.

I am thinking of porting uCLinux to my LPC1788 custom board.

The board consists of around 4 MB of NAND flash and around 32 MB of RAM. Is this enough?

Frankly, I don't have much idea of how to port uClinux onto Cortex m3. Where do I begin? I think the first step is the bootloader, then compile uCLinux and my application: am I right?


texts: Calculating the gain of a specific transistor amplifier circuit

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NOTE: There is an error in the drawing above — C1 should be connected to the emitter, not the collector.

Hi Electronics SE, hope this is the right place to ask this, if not I'll gladly take it down and move to a different resource.

Yesterday during a practical lab exam on bipolar transistor circuits, the pictured amp was given. I spent a lot of time trying to figure out the gain value, and just couldn't figure it out.

The main problem was not being able to express v(1) without parameters of the second transistor stage (mainly v(eb2)). What would be the correct approach in analyzing this circuit in the small-signal (AC) regime? The early effect is neglected.

I'm pulling my hair out over not being able to solve this, would I need to create a system of equations with both gains of each stage and solve it that way?

Thanks in advance.


texts: What will be the effective transconductance of the system? We have an amplifier of the voltage gain of -2 and R, C connected as shown. I believe We can't judge if the system is in negative feedback because it is not given here. How to approach?


texts: Using 4 AA batteries to charge mobile phone

texts:
There are three scenarios:

4 AA batteries connected in series would produce 6V. I'm planning to supply the output to an LM7805 regulator and produce 5V. The output from the regulator then will be connected to the charger cable (torn apart from the original phone charger)  which will be inserted in the phone (3.7V 1300 mAh Li ion battery).
I'm guessing although the batteries will produce 6V, the current supplied will be too low to charge the phone. So adding 6 batteries instead and following the same procedure as mentioned in (1) could work.
4 AA batteries connected in series and the output (6V) is delivered to a  XL6009E1 boost converter (5V to 35 V) tuned to produce 15V. The output is then supplied to an LM7812 regulator to stabilize the voltage output and the output from the regulator is directly supplied to a 12V  lead-acid battery.

Questions:

I need to know if all these systems will work. If not, then please mention the corrections required.
The current supply will be quite low to charge the batteries in all these cases. Is there any combination of series-parallel connection for the AA batteries to obtain the optimum voltage and current ratings?


texts: Lenovo Y580 battery - Panasonic NCR18650b MH12210

texts:
I am new to the group, so thank you for this great community. I am a student and "DIYer" and like to repair simple electronics.

Anyway, so here is my situation:
Want to repair my laptop battery as there are no more spare being built (Thank you Lenovo) and cracking open the cover of my pack to identify the cells I have these inside: Panasonic NCR18650b MH12210.

Now according to may pack label, I have 10.8 v 72WH 6700 mah, meaning each cell around 1116.6 mah. But looking online the cell is rated at 3200 - 3400 mah!!

Could someone please let me know if there are variation to this cell? meaning there is 1100 mah version of it? I could not find it. Or other cells I can use instead.

I have attached some images of the battery pack and cells.

Any help / suggestion would be appreciated

Cheers


texts:
I have trouble understanding the operation of the following circuit:

This is the given description of the schematic:
"This is a voltage controlled multivibrator that is used as an acoustic volt meter. The supply voltage is 9 V and the measure range is also 9 V. At the moment when one of the transistors of the multivibrator starts to conduct, the base voltage of the other transistor drops to -9 V. After this, the 10 nF capacitor is charged by the current through the 100 kΩ resistor to around +0.6 V in approximately 0.65 ms, at which point the circuit switches states."
I am not sure what to 1...30V means here. I don't know what sort of multivibrator circuit this is. As I see it, there are 2 switching capacitors, connected in a feedback network, along with two time delay capacitors. I am not sure how to transistors are biased. Also what happens when the left transistor (Q1) is off? I am also not sure what voltage the collector of Q1 does have and how it affects the capacitors' plates (and thus their voltages).


texts: Chip antenna layout suggests shorting feed line to ground?

texts:
I'm working on layout and trying to replicate the test configuration for this chip antenna. I'm a bit confused, however:

From datasheet: https://media.digikey.com/pdf/Data%20Sheets/Yageo%20PDFs/ANT3216A063R2400A_Rev2014.pdf
If I'm reading this correctly, the feed comes in on that 'L' of metal. However, the skinny stub above that (the roughly 0.74x1.85 stub) also connects to the same contact on the chip antenna. Given the stitching vias, I believe that stub and the majority of the top layer metal is also GND. However, this would mean that the contact on the edge of the antenna would effectively short the feed to ground when it's attached (the 0.32mm gap further supports that the L and stub are separate I think). I know antennas do some funny things sometimes, but I'm not sure I've seen something so directly shorting the feed to ground. Am I reading this right, or what am I missing?


texts: looking for highly accurate phase detector

texts:
I'm looking for a highly accurate phase detector for my capacitive sensing application.
In the application, the capacitance is in the range of 1 ~ 10 pF.
I've been able to get the capacitance via analog device's AD7745.
However, I was requested to have the dissipation factor measured as well.
I've been trying to seek a chip to do the job, unfortunately not yet.
I've came up with the idea of using a phase detector, with the information of which, I'll be able to calculate an approximate value of dissipation factor myself later on.
So my question is, is there such a phase detector that can detect the phase difference between the voltage and current across the capacitive sensor with a very high accuracy?
with accuracy I mean: the capacitor is a nearly ideal capacitor with dissipation factor of less than 0.001, so the most interesting part of phase difference is between 89 ~ 90 degrees...

The interested frequency range is DC ~ 1Mhz.

thanks !


texts: What does the term "turnkey" means or refer to in the Engineering/Manufacturing environment?

texts: I keep hearing this expression thrown around when talking about or to PCB fab houses. Can someone tell me what it means, or refer to ?


texts: Multicore ARM how to assign a critical task to one dedicated core

texts:
Suppose I have a multicore ARM processor (to make it simple assume 2 cores with an unshared cache between the 2 cores). Suppose my system contains a critical task and several non-critical tasks.

Therefore, can I assign the critical task to "core 1" exclusively. And all other to "core 2" exclusively?

If so, what are the best practices from an implementation point of view [assume I use C]? Should I use a library (if so which one) ? An RTOS?


texts: What does the bandwidth of a probe mean?

texts:
For example, when I have the P2221 ( http://www.farnell.com/datasheets/1808826.pdf ),The bandwidth when setting it to 1x, would only be 6Mhz. Looking at the input resistance and input capacitance: \$ \frac{1}{(2*\pi*RC)}= \frac{1}{(2*\pi*110*10^{-12}*1*10^6)} \approx 1447 \$ and not 6 million. How do you get to 6 million?

Does this bandwidth mean there's an attenuating for signal higher than 6Mhz or does it mean it will filter out all signals above 6Mhz or something else? How can I calculate the frequency when attenuating starts? When setting it to 10x, the bandwidth is now 200Mhz. Why this difference, when the capacitor is roughly 10 smaller and the resistor is roughly 10 times bigger, so RC does not change that much.


texts:
Is there standard that recommend guidance of particular colors of solder mask?

A while back I was told by a local assembler that BLUE typically indicates the circuit is ROHS compliant. Yet my Google foo does not find any supporting evidence. Were my Google foo is swamped. So there may be something I just don't see.


texts: Calculating total capacitance of a circuit

texts:
simulate this circuit – Schematic created using CircuitLab

Question is, how to calculate capacitance of such a circuit. I made a schematic with resistors (because that i can measure) and from there i saw that the C4 value is always ignored, but i can't be sure the capacitors will act the same. I have been trying to break it down into smaller circuits, but the C4 just makes me hold my head.

How should i break it down into series or parallel capacitors so i can actually calculate the total capacitance?


texts: Why would a DAC have both Vcc and V+ power supply?

texts:
I'm trying to understand the datasheet for the AD5535B DAC. I think I can understand why there would be a DVcc (digital Vcc) and AVcc (analog Vcc) to prevent digital switching noise to enter the analog circuitry and to allow maybe 3.3V digital signals. In addition, there is a high voltage input Vpp. However, on the analog side we find both an AVcc and V+. They have the exact same voltage ratings. The datasheet has only this to say,

If the number of supplies must be reduced, bring all supplies back separately and make a provision
on the board via a link option to drive the AVCC and V+ pins from the same supply.

I guess this means that they recommend to still have separate power supply connections to the eventual PCB, but allow them to be tied together if needed. But that still gets me no closer to why one would want them separate at all.
What is the explanation for these two separate supplies? Why should I bother? The manual for the evaluation board just specifies to use a single power supply for V+ and AVcc.


texts: Can a circuit "just stop working" after not using it for a long time?

texts:
simulate this circuit – Schematic created using CircuitLab

I had a very simple circuit that used a mosfet with an arduino to power a motor. The whole thing is run off of a 12v supply (5v reg. added to supply power to the arduino). The circuit was working fine before (a few months ago), but when I tried turning it on today, the motor wouldn't start. Here are my findings:

Multimeter says the motor wires (w/o motor connected) are in fact getting the needed 12v, but it drops to under a volt when I reconnect the motor.

I tried connecting my motor directly to the 12v supply, but it just made a big spark (I am not sure if the motor actually started, but it should not have sparked the way it did).

Nothing 'smells' like it is burned out, and nothing got abnormally hot. Does anyone have any idea as to what could have happened (I used the same PSU as before).


texts: Why does AC/Sweep in Cadence always require a starting and stopping frequency?

texts:
It seems as if there is no way to simply test a circuit with an AC voltage source at a single frequency.

How does someone test a circuit that plugs into the main voltage at 60Hz? Is it really mandatory that you account for every single frequency up to and including your source's intended frequency?

I'm angry at CADENCE!


texts: Help with high side MOSFET driver IC configuration

texts:
I am building a non-isolated buck converter with a N channel MOSFET(2SK4017), I am using the FAN7382 High and low side gate driver. I just want to verify if my wiring is correct before I construct the circuit.

Since I only need the high side output would it be sufficient to ground pins 3, 4 and LO? Do I still need to connect Vcc to the supply?

I will be using a fast recovery diode, Rboot=5 Ohm and Cboot= 100nF.

In my application it will be 12V instead of 15V and the PWM signal driving HIN will have a frequency of 10kHz.

Will this design work?

Cheers!


texts: Reducing input voltage spikes on buck converter

texts:
I am using a buck converter to drop from 5V to 1.8V to be able to drive both of these voltage levels in a single design. The buck converter works correctly to generate a clean 1.8V supply, but the input side of the buck converter, the 5V side, is being contaminated with switching noise spikes of around 1.5 volts as a result of the buck converter being in the circuit. I have used the FT440A and AP3429 chips.

I have tried playing with the capacitance on the 5V input to the buck converter as well as adding diodes and inductors, but so far I have had no real effect on the spike amplitude. Is there a set of standard approaches to removing this sort of input noise that someone could highlight?

The default circuit is all that I am using with the exception of trying numerous modifications on the Vin side to get rid of the noise being seen:

Here are the input spikes that I see:

As far as layout is concerned, C1 is as close to Vin as possible. I have tried from 4.7 to 22uF capacitors. I also tried adding 3.3uH and 4.7uH inductors between before Vin.


texts: Design dc-dc converter for adjustable voltage

texts:
I would like to use the LM61460 (datasheet) to build a buck converter with a Vin of 24v-33v and an adjustable output from 5v at 3a to 20v at 5a for USB power delivery. I used TI Webench to generate a design for both 5v 3a and 20v 5a.

These are the biggest differences:

Value of the inductor
Rff and Cff aren’t present in the higher power design
BIAS is connected to Vout at lower voltage and to gnd at higher voltage

For the inductor, I would pick the biggest value. And I would connect the BIAS pin to gnd, since the datasheets states to ‘connect to output voltage point to improve efficiency’, so it should still work when connected to gnd.

Is this correct and what should I do with Rff and Cff?


texts: We are using BQ2057WSN charging IC to charge a 7.4V, 6600mAh Li-Ion Battery by providing 12VDC,2A power supply.  According to my calculation the charging current is set at 625mA. But while charging, the BQ2057 charging IC and the mjd32ct4-a (the NPN trasistor) is heating up. Any drawback in my design? I am attaching the images below.


texts: Why using a High and Low side driver in BLDC?

texts:
I'm working on a small project of mine and I need to implement a motor driver in order to control a 3 phase Brushless DC motor.

By googling, I've read that I need a High and Low side driver to control the couple of NMOS used the generate on of the phases.

Can I just connect the pins of my μC directly to the MOSFETs and just enable and disable it via software?

Could you explain me why do I need such a piece of hardware?

I've seen the L6234 Three phase motor driver from ST, and they use some logic ports to manage the enable/disable of the inputs.

Thank you in advance!


texts:
What is the Q-point of a transistor?

Why it is needed?

How can we set this Q-point of transistor?

Please explain it as I am having difficulty understanding this concept.


texts: Handling "Upside-Down" IC Pinouts on PCB

texts:
I printed a board recently and, long story short, the pads aren't laid out correctly for two IC's: a SOIC8 MAX1771 and an 80-pin HV507. I moved all the pads from the top to the bottom layer, but forgot to flip the sides. Thus, along one side of the SOIC8 pads, for example, the connections number 4–1 instead of 1–4. I did something similar for the HV507. To give a better idea of the issue, if you pushed the IC through the board, then bent all of its pins upside-down, it would be connected correctly.

I can re-print the board, but I'd like to be able to test with the board that I have. That said, I've had difficulty finding a DIP adapter for the HV507. Is there any work-around for a reversed IC pinout that doesn't involve extensive new materials?


texts: Benefit of higher frequency transceivers?

texts:
What would be the benefit of higher frequency transmission? I was browsing through a website looking at some parts and came across two transceivers, one operated in the 434MHz band and the other the 915MHz band. From my perspective, it seems that it would consume more power transmitting at over twice the frequency.

Link to the product: https://www.sparkfun.com/products/9582


texts: Class AB Amplifier - Weird oscilloscope output

texts:
I have built this little kit for a class AB Amplifier. This is the schematic if you do not want to follow the link

It works fine, I can hear decent sound.
I then tried to check the output with an oscilloscope to learn a bit more. I am using a bitscope micro USB oscilloscope. I have replaced the speaker with 5 47 Ohms resistors in parallel to cope with the load. The voltage peaks match what I get in LTSpice, but I was a bit surprised to see the straight lines on the descending and raising part of the wave.

This is for a 50mV peak signal @ 1kHz (the maximum allowed by the design). The clipping is obvious when I increase the signal, and the strange behaviour is still there even if I halve the signal to 25mV.

The device is also a function generator. This is what the input signal looks like (100mV sine wave).

Do you think it is because of the oscilloscope limited sampling or some kind of distortion?
Solution (I think)
The answer from bobflux made me think that problem was in the quality of the signal. If you look at the signal trace you can see that there is a lot of noise.
The solution was to introduce a 10/1 voltage divider (10K/1K) and increase the input signal to 1.1 V. This creates a beautiful sine wave (although it is seems a bit attenuated).


texts: Purpose of resistor across op-amp inputs

texts: The following (from TI app note slaa414a) is an active bias-T that sums the AC and DC inputs to drive a load for the purpose of testing PSRR. What does the 100 Ohm resistor across the inputs do? Both inputs have DC paths without it.


texts: A question about SPI flash operating frequency

texts:
I'm working on a flash chip "W25Q128BV". I get really confused on the operating frequency of this chip.

As we can see, "Read Data" instruction is comprised of 3 steps for master: sending opcode, sending address, and reading data from flash.
My question is that can I use 104MHz for sending opcode or address? I think master must use clock frequency below 33MHz for reading data.

And I have the same question for Quad SPI and Dual I/O instructions. The datasheet says the max frequency for them is 70MHz. Taking instruction "Fast Read Quad Output(6bh)" for example,
this instruction is comprised of 4 parts: sending opcode, sending address, sending dummy clocks, reading data. What is the max frequency of dummy clocks, 70MHz or 104MHz? What is the max frequency for sending opcode and address, 70MHz or 104MHz?

I have spent lots of time for this question on Google, but I couldn't find similiar questions and answers. I found that most people use a low frequency to control spi flash such as 30MHz. So they don't need to worry about the max frequency of a particular instruction. For some purpose, I have to operate this flash chip as fast as possible.

What's more, I also read some datasheets of similiar flash chips, such as N25Q128A and S25FL128. All of these flash chips use lower max frequency for instruction "Normal Read", but the datasheets don't tell the specific frequency request for different parts of instruction "Normal Read".


texts: How to control output voltage of DC to DC Step Up Fly Back?

texts:
I need to control the output voltage of  Isolated Flyback Step-Up power supply using an MCU may be using DAC or PWM or via a digital pot,
how to do this?

spec
Vin 5V - 8V

Iout 40mA

Vout max 100V
Vout control range 0V-100V or 5V-100V

I am using ti power bench to design the flyback isolated converter
I don't know how to control the output voltage of it


texts:
I know this question is not new, in fact I learned the basics of this circuit from sites including this one. However I am planning on making a PCB with it and do not have the luxury of multiple attempts at this one. It is to be a 14A at 16V current limiter. This current limiter is going to be used as a desaturation protection on an inductor charging leg in a SMPS Boost converter. I just want to know if there is anything I have missed or any tips in particular? Hopefully a good enough fit for low power loss and low circuit complexity?

PLEASE IGNORE all part numbers and component values. I just drew it using the available components in Circuit Sim.

simulate this circuit – Schematic created using CircuitLab

Thanks


texts: How does frequency modulation takes place?

texts:
It is said that in frequency modulation the normal wave represents a '0' (False) and a more frequent wave represents a '1' (True).

Is there any particular rule that the normal wave's frequency should continuously be the same? How actually is this "normal frequency" found out?
Consider an example of a wave that has first 3 waves in a time period, then 2 waves and finally one wave. How would it frequency modulate it?


texts:
I got PIC24FJ192GB106 (64 pin package) and I cannot get the I2C module working at all. What is the easiest and most straight forward way of testing, whether the module is OK?

I am using I2C1 module, (SCL1 - pin 44, SDA1 - pin 43).

BRG register = 39; // 100 kHz for Fosc = 8 MHz

// Control register
    I2C1CONbits.I2CEN = 1;
    I2C1CONbits.I2CSIDL = 0;
    I2C1CONbits.SCLREL = 1;
    I2C1CONbits.IPMIEN = 0;
    I2C1CONbits.A10M = 0;
    I2C1CONbits.DISSLW = 1;
    I2C1CONbits.SMEN = 0;
    I2C1CONbits.GCEN = 0;
    I2C1CONbits.STREN = 0;
    I2C1CONbits.ACKDT = 0;
    I2C1CONbits.ACKEN = 0;
    I2C1CONbits.RCEN = 0;
    I2C1CONbits.PEN = 0;
    I2C1CONbits.RSEN = 0;
    I2C1CONbits.SEN = 0;

// starting the module
I2C1CONbits.I2CEN = 1;

// setting the START CONDITION
I2C1CONbits.SEN = 1;

There is no response. The Start Condition is not executed. The I2C pheripheral is on NON-remappable pins. Whole TrisD register (pin 43 = D9, pin 44 = D10) is set as input (after reset). The pins has pull-ups (3.3 V, 4.7 kOhm). I have also tried to set corresponding bit in ODCD to 1 (digital pin), and 0 (open drain).

Have I missed something?
Microcontroller is working fine (UART, PWM, reference clock, ADC, ...).

I would appriciate any guidance.


texts:
I'm designing a PCB for USB 3.0, the specifications for Differential impedance comes at 90 ohms with a tolerance of +- 5 ohms.

I've used different calculation tools but when I have to hold these specs my traces are really wide in comparison to the usb3.0 printed circuits that I have as example, even with the same PCB material.

I searched the Internet and found some specs for the width and spacing but if I put those into the calculation tool it shows 170 ohms..

Anyone have an idea how manufacturers solve this?

I also had a question about manufacturers putting multiple Vias from top layer to bottom layer. In the past I read some articles about this but can't seem to remember what it's for, anyone have an idea about that?

Here is an example :


texts:
What is a good way to secure cables to a PCB?

There are some good advice in the following post, but the application is slightly different:

Securing electrical cables to holes in enclosures?

In this case, the strain-relief/securing of the cables will be onto the PCB, not to a casing. (The PCB will be encapsulated or just given a layer of conformal coating, so there isn't any casing.)

I'm considering to run the cables to the edge of the board. Then at the edge, press the cables between the PCB and a metal bar. The metal bar is pressed against the PCB with bolts and nuts (nylock or thread lock).

What might be the problems of this solution and what other methods should I consider?


texts:
I was studying the VHDL uart core given here. At the bottom of the page is shown the transmitter code. Notice the line

 tx_data <= "1"&data_i&"01";

This line adds the start and the stop bit to the data string. But why is there an additional '1' bit at the rightmost of the string? Wouldn't the code below suffice?

 tx_data <= "1"&data_i&"0";

There is no parity implemented in the core, and only 1 bit stop. Thus, that additional bit really confuses me. Why is it there?


texts: Many ICs have short circuit protection built in, but how do they stop current flow in case of a short?


texts:
I have a circuit with two DC power lines coming from BAT1 (1A) & BAT2 (2A) (two outputs of a power bank). There is a sliding switch on the power line of BAT1. I would like to keep only one switch to control both power lines.

I have some N-Channel MOSFETs (RFP30N06LE), do you know a circuit that will allow me to open/close the power line of BAT2 using the state of power line of BAT1 ?

For information, the charge on line 1 is an Arduino and a video camera, on line 2 its a DC motor and a servo motor.

The easiest solution seems to use relays but it looks like overkill to control 5V with 5V... It will also consume more power than the MOSFET I think. I would like to know if you have better solutions.


texts:
For clear any mistake, the question is: Why the LED started to blink after being replaced?

The goal was to replace the blue leds with red leds, after replacing the leds one of them started to blink, each blue led is connected to it own resistor of 100Ω

There are three tracks in this board with the following schematic. (Before Replacing there was just one track with resistor and led, on the other two there was no led (just resistor))

simulate this circuit – Schematic created using CircuitLab

And one track with this schematic

simulate this circuit

Based in the comments I did a calculation, but it was wrong, based in the answers I realized what was wrong and learned how to do it correctly.

First of all, I searched for the voltage of each LED, but I found a lot of tables with different information, so I found a video in portuguese in youtube with a small circuit to find the voltage of a LED.

simulate this circuit

Now I have:

Using the Kirchoff's Voltage Law, I've calculated the resistor voltage.

After that I've applied the Ohm's Law to find the Current(I) in this circuit.

With the current(I) in mind I could do the inverse to find the resistence value for the red led.

"Just for fun", I've followed what "K H" said and calculated the current for the red LED using a 150Ω (what I will use) resistor:

Ok, with that I found the resistor I need to use, but "one track" have a place for a second led in parallel, so I calculated the resistor to place a second red led there.

So I'm using a 68Ω to this circuit.

I know that this added 60mA (100mA Total) in the source, I could use something near to 400Ω to drop the current to 8mA per LED so I could drop the usage back to 40mA, but the brightness would be low.


texts: Help with assessing maximum operating voltage of a circuit

texts:
I am designing a field charger for charging lipo batteries while I am out flying and on the go and I already have a huge 16000mah 4S lipo available that I could use to charge my 1300mah 4S and 2200mah 2S lipos while I am out and about.
I want a cheap, but more importantly compact solution so although there are multiple battery chargers available, none seem to meet my needs.

Not wishing to re-invent the wheel, I have come across this charger that a friend uses that is actually very accurate despite its cheapness (around £9GBP delivered - https://hobbyking.com/en_us/hobbykingr-dc-4s-balance-charger-cell-checker-30w-2s-4s.html)

I am thinking of using 4 of the boards from these so I can charge 4 batteries added at different times while I am flying.

My issue is that the operating voltage is 9-16V, fully charged 4S lipo is 16.8V.

I understand there is usually some allowance made in this figure so I opened up my friend's unit to inspect. I cannot seem to find any components that are obvious to me that cannot handle 20V.

Would anyone be able to assist me in trying to assess before I either buy 4 of these, or otherwise try it out and blow up my friend's charger? (always a risk I know).

All of the caps are rated 25V, of the smd fets I can identify, those are rated at 20V. My question is if looking at these two photos I should pay close attention to any particular components.

I COULD use a buck converter to convert down to 12V first, but that will add bulk and reduce efficiency, so I wish to avoid that if possible. I will obviously check that all chargers are charging to accurate voltages before deployment. (I am experienced with lipos even down to a scientific level where I have designed some, so I am aware of the dangers, this is just for my hobby, nothing else.) I also wish to learn more about how to assess circuits that are not my own / well documented.

Many thanks in advance.

EDIT:
The inductor for the buck/boost stage is pulsed using what appears to be an 'SI4606' - http://www.datasheetspdf.com/datasheet/search.php?sWord=Si4606

The control MCU is a Holtec HT46R066B - http://biakom.com/pdf/ht46r06xbv110.pdf
But VSS is max 6V so like other ICs seems to be supplied by a reg...
Other IC chips can be identified but they do not seem to see, from what I can tell, V_Input directly.


texts: I have a Snap Circuits kit which has this oscillator circuit which I am fascinated with. I know how a relay buzzer oscillator works and it is pretty cool. This circuit uses a potentiometer, polarized capacitors, and bipolar transistors. I am familiar with these components. I am just trying to figure out how this circuit works and why the light flashes/the speaker pulses when I turn the circuit on and where the circuit flows. Can someone please help me figure this circuit out? Thank you very much.


texts: What is the simplest op amp level shifter? That is, no gain and both inverting and non inverting configurations, for AC coupling


texts:
I've got the next simple VHDL process where I'm checking if an input is 1 and then change a status LEDS:

   LEDSTATUS: process(clk)
   begin
      if(clk'event and clk = '1') then
            if (lp_good = '1') then
                stat_led  <= '1';
                stat_led2  <= '0';
            end if ;
      end if;
   end process;

I checked physically on the board and the lp_good signal is 0, but it changes the status of the LEDS. If I change to check if 0 (if(lp_good = '0')) still executing the if statement.

Any ideas what I'm missing or is wrong?

Thanks in advance.


texts: Building a low-power solar/wind buck-boost converter

texts:
Using a 18V(max) solar panel, I'd like to charge a 12V lead-acid battery. I'm working from the basic inverting buck-boost circuit. My main question is, being a relatively low-power circuit, can I connect the output directly to the appropriate battery terminals, or would I need to re-invert the polarity before doing so?

It'll be monitored / driven by an Arduino. This is the inspiration: Tim Nolan's MPPT Solar Charger.

A future expansion I'm planning for this is to add a (rectified) wind turbine input as well. Obviously this would need a separate buck-boost circuit, but the question there would be: how safe would it be to connect the output of the wind buck-boost to the battery, in parallel with the solar buck-boost? I'd assume that if my software is written right, the output voltage will be the same from either side so there should be minimal problems. Please correct me if I'm wrong ... but that's a future consideration.

My significant parts list:
Arduino for the brains/PWM
IR2104 MOSFET driver
IRF540 MOSFETs
MAX4080S Current sense
Resistor divider
Schottky diode for the buck-boost section
100uH inductor for the buck-boost section

Edit: I like Olin's simple answer, but it's not the answer to my question, as it doesn't give me any guidance with my project. Any other takers?


texts: Why is the input trigger pulse in a monostable multivibrator fed to the base of the transistors through a capacitor and not an inductor or resistor?

texts: In a monostable multivibrator, one of the transistors will be fed with a trigger pulse using a capacitor. I have heard about capacitor coupled circuits like stagger tuned amplifier where one single stage is capacitively tuned to the other stage. May I know why a capacitor was used in the feeding section of the trigger pulse?


texts: What is the standard way to make a Peltier power supply with variable power?

texts:
Possible Duplicate:
  How to drive a Peltier element?

I want to control a few Peltier using MCU. I think the easiest way is using PWM, but I feel that the efficiency is very low and It maybe will damage the Peltier.

Does anyone know what is the standard way to make a Peltier power supply with variable power?


texts:
On our quadcopter, we're carrying a switching circuit that would allow the switching between two batteries. When using the 2 Channel Relay Module, the quadcopter is having a hard time flying with it. When directing the battery to the quadcopter, the quadcopter doeesn't have a hard time with flight. Is there such a big power loss from such a small relay? Are there any other options? or is there a solution?

The reason for switching the circuit is because one battery will be used by the quadcopter, the other one will be charging. So after the first battery is drained, the other battery will then be used for the quadcopter, the other one will charge. So on and so forth.

This is the relay used by our thesis.

http://www.sainsmart.com/sainsmart-2-channel-5v-relay-module-for-arduino-raspberry-pi.html


texts:
What will happen if I connect current transformer in reverse direction, means instead of applying current in primary if I apply some mA of current in secondary(less than the rated secondary current) then what will be the current in primary (assume that in primary I have kept a thick wire with ammeter in series).

I tried this experiment with TT-50SD. I applied 5mA,60Hz current to secondary of this CT and found that current in primary wire was only 1.444mA and increasing secondary current further was not increasing this primary current. Which means core was saturated, is there a formula which will give this saturated primary current value and is it harmful for CT to do this kind of experiment.


texts: Switching between USB power and single alkaline battery

texts:
I've read the numerous other questions addressing this topic, but I'm not sure if any of them apply to my situation.

I am designing a device that will run off a 3.0-3.3V supply voltage and draw no more than 40mA when active. When the device is connected to a USB port, it should draw its power from the bus. When no bus voltage is present, I want the device to be powered by a single 1.5V AAA battery stepped up to ~3.3V using a boost converter like a TPS61097 or a TLV61225.

I don't want to just diode-or the two supplies together: when USB power is connected, the boost converter should be inoperative and there should be (ideally) no current drawn from the battery. Ideally, the device's current in the inactive state should be < 10µA, so I don't want to add another "expensive" chip like the LTC4412.

I think the right answer is to run the battery voltage through a depletion-mode MOSFET that shuts off when the 5V USB supply is present on the gate, but I'm having trouble wrapping my head around some of these concepts, and I'm not sure how I'd go about choosing a part.

So, my questions are?

What do I put in place of the question mark in the diagram below? If it's a MOSFET, how can I choose the right part?
If I use an LDO to get 3.3V from the USB bus, I'd need to put a protection diode on it, right?
Even if there's no input current to the boost converter, do I still need a protection diode on its output?

simulate this circuit – Schematic created using CircuitLab


texts: How is Emitter Coupled Logic different from Current Mode Logic. I have seen written in "Microelectronics Circuits" by Sedra Smith that CML is based on ECL . If it is so can anybody explain how they are related?


texts: How to trigger 12v environment on PowerBank

texts:
The Desired Result: via rechargeable battery, power a 12v 1 meter led strip that takes 1.2 amps.

I have purchased an orico power bank with 12v 1.35amps output as it meets the dimensions needed for the project.
https://www.newegg.com/Product/Product.aspx?Item=0SC-00TX-00002&cm_re=12v_power_bank--0SC-00TX-00002--Product

The issue: the power bank automatically detects the charing environment and currently is stuck with the 5V output option and can not power the leds.

Possible Solution: I am curious if there is a way to, perhaps use a micro-controller to cause the power bank to detect the desired charging environment to output the 12V.

alternatively: if there is another power bank that outputs 12V and 1.35+amps close to these dimensions: 102 x 76.8 x 21.5 mm that doesnt require additional steps, id be open to purchasing another. ( I have searched quite a bit for rechargeable packs and seem to have only found the one listed above)

or

some configuration of rechargeable batteries like the 18560 to power it (I'm just hoping to use a recharge pack as it often has additional feature to keep it more safe)


texts:
In From Schematic to Reality @ beavisaudio.com, the following is written:

  ...
  R2 and R4 form a voltage
  divider. This simple snippet is in charge of providing half of the 9
  volt source voltage as a reference point to the base of the
  transistor.

Why the DC voltage in the BJT's base would be half?

Edit (22:34 UTC, 4 Aug):

I've created a circuit as advised by jippie:

simulate this circuit – Schematic created using CircuitLab

By doing a DC analysis, I've seen that the voltage in the BJT's base is 697mV.
Now I almost feel like an electronics engineer :)


texts: How can I signal a USB charger to provide power?

texts:
I want to use an 18650 battery pack to power a circuit with 5 volts at a low current. The 18650 battery pack has a USB output which provides 1 amp at 5 volts. I measure voltage drop across the left and right pins and it’s only .77 volts. When I plug in a device like a phone, it goes to 5 volts and a light turns on on the charger board.

How can I get power without talking to the charger board?

Ok actually I solved my own issue through dumb luck. I plugged it in and it turns out my clumsy self had shorted the usb shield to positive and it tripped protection until it was plugged into the charger. Now everything is working great @5 volts 300mA (I’m powering 4 hall sensors).


texts:
My Arduino Uno R3 gives me an electric shock upon touching one of its pins when my legs are on the ground.
The shock is not that trivial since if the pin is related to some LED the LED lights up which means that this at least 5mA of current or so. And of course is not from its 5V outputs.
The Arduino is powered from USB-2 from my computer and even the ground pin gives this shock.
I guess this has to do with my computer power supply it's a Hector 350W with two pins without an earth  onnection.
Is there a way to just get rid of this annoying shocks?
I am not that expert with electricity but I am not a beginner either so I think I can handle it if someone just pointed me to where I can start searching or something.


texts: Can USB device detect if upstream/root is suspended?

texts:
I would like to make/get USB-powered fan, which turns-on only if laptop is not suspended (extra: connected via USB-hub). VBUS monitoring isn't sufficient, ie. powered hub, or laptop with USB wake-up support.

Is it possible for device to know/detect, whether laptop is suspended or not?


texts: I'm trying to learn how to make these circuits but have no clue if I'm on the right track?

texts: I've recently been doing some online tasks but I am really struggling to understand how build this circuit in multisim. I am also struggling to calculate the values listed in 2. and have tried to find out for myself but have had no luck. I also don't know where these values are calculated, "for each components"?? I had a go but really don't know if I'm even following the correct steps given.


texts: How can I determine the battery life for a continuously recording camera module?

texts:
I'm not an electrical engineer, so please forgive my lack of technical terminology. I'm researching an idea that requires me to create a PCB that will have a camera module record video and store it to a microsd card. I'd like it to be able to record for 8-12 hours. How can I calculate what battery will get the job done, given a specific camera module and microcontroller?

What is the smallest battery that I could use to accomplish this, you think?


texts: What properties of metal makes make them suitable as EMF shielding material?

texts:
What properties of metals make them effective at shielding against EMF, and which metals are typically used?

How does Aluminium, Steel, Copper and Lead compare?


texts: Whats the point in conserving electricity if the AC current produced cannot be stored?

texts:
If we cannot save the ac current produced in a battery or some device like the DC current there is no point in conserving it because current once produced should be consumed somehow!!
My faculty said storing AC current is a tough task


texts: Shorting ground and left (or right) of 3.5mm audio jack from the computer

texts: I'm trying to build a shutter release for my Canon SLR that is controlled from the computer. Since the shutter release is simply shorting two points on the headphone jack together, is there a way to short two pins on the headphone jack together from a computer?


texts: How to make rechargeable trimmer work without battery?

texts: I had a rechargeable beard trimmer which was out of work as battery was not charging anymore so yesterday I took out the rechargeable battery and decided to run it directly. As motor needed dc current I provided It through nokia charger and voila motor rotates however when I put the blades back on motor, motor has some vibrations but can't rotate the blades. For which I was thinking voltage or current may be small but when I wire the trimmer to D cell battery blades work. So here why motor is not able to rotate blades when run on a mobile charger, and works well on D cell battery?  When charger provides more voltage than D cell battery. D cell as all know 1.5v whereas charged gives 9v.


texts:
I made a circuit using relays to control when to start some motors. Since there were four motors that should be connected, I made four identical circuits.

Testing each individually, they worked. But when you call everyone together, there is a big problem.
One of the relays continuously switches the contacts very fast, without me giving any commands. It starts, vibrates for 4s, stops, waits 15 seconds and does it again.

I'm feeding them all with a source made by me that puts out 5v and 12v. I know that it feeds correctly because it is feeding other circuits besides these. Does anyone know what the problem might be?

Circuit below:

The power supply im using is shown below:

I'm using a 30V 5A transformer.

All circuits together:


texts:
I tried to simulate an RC lowpass circuit, but MultiSim doesn't quite provide the expected result.

Q2 being npn-type, and forward-biased, it should immediately turn on, becoming low-impedance on its collector-emitter path, so C3 should see
almost GND on its lower terminal. On scope channel 'B', I have ~0,76V as expected, but channel 'A' carries a constant 5V where I would like to see
a nice exponential.

p.s. There is no change in things if I pass an initial condition to the
capacitor (IC=0V).

Any clues to what I did wrong?


texts: Sensible way to power an OLED display from AAA Cells

texts:
I'm designing a small battery powered device and I want to use an SSD1327-based OLED display. Unlike the SSD1306, this one doesn't appear to have an integrated boost circuit to power the panel, which wants 8V-18V.

My intention is to power my device with 2 NiMH AAA cells (or 1.5V alkaline) so I will need to boost the ~2.4V up to 3.3V for my controller and ~13V for the OLED panel.

The panel only draws a very small amount of current: ~600uA, and I'm lead to believe that this wouldn't be enough load on a traditional boost converter from an efficiency point of view.

so, my question:

Given ~2.4V from 2xNiMH AAAs, should I:

1.

1 boost converter @ 3.3V
1 boost converter @ ~12V
both powered directly from the battery.

2.

1 boost converter @ 3.3V (battery powered)
1 boost converter @ ~12V powered from 3.3V

3.

1 boost converter @ ~12V (battery powered)
1 linear regulator @ 3.3V powered from ~12V

As far as efficiency requirements go - I'm building a toy, so I only really want lifetime measurable in a handful of hours, not days or weeks.


texts: How do I do basic circuit analysis with resistors rated in watts instead of ohms?

texts:
In my electrical circuits class, we've spent the last six weeks learning circuit analysis with resistors rated in ohms. Now, out of the blue, every question on the next practice exam has the resistors rated in the watts they consume. Here is a question from the practice exam where I'm supposed to find Ix.

Am I really supposed to find all of the node voltages by substituting the resistance values with V^2/P (or some manipulation of it) and then doing a loop current analysis? That gives a bunch of quadratic equations instead of making things easier.

I feel like I'm overlooking something mind-blowingly simple here. I've spent the last few hours searching for help on this and I can't find anything for this type of problem. Any help to point me in the right direction would save what little hair I have left on my scalp.


texts:
This might be obvious but I don't understand why RS-232 needs a stop bit. I understand that the start bit is necessary to notify the other end about the beginning of a transmission.

Let's say we are communicating at 9600BPS. We go from high to low, so that the receiver will know something is coming. The receiver also knows that we are at 9600BPS and it will receive 7 bits of data in total.

So, after receiving 7 bits, the transmission will end. Since we can determine the end of the transmission just by calculation, why do we need a stop bit as well?


texts: Intercepting signals from vintage computer (common ground)

texts:
I am trying to reverse engineer the signalling for a peripheral to an old 4-bit computer and eventually I want to emulate the peripheral and send the appropriate signals back to the computer.  I know that the logic levels are 5V TTL compliant and that the signalling is very slow (think less than 100Hz).  I plan to connect a small microcontroller (like an attiny) on the peripheral bus to sniff the signals and then to communicate those signals via an UART->USB FTDI chip that will then connect to my (modern) computer.
I just want to double check my understanding about tying the grounds together to allow the communication to take place.  The 4-bit machine has its own power supply, which will be powering the peripheral bus.  My modern computer obviously has its power supply which via USB will be powering the FTDI chip and microcontroller.  Am I correct in understanding that all I have to do is connect the ground from the 4bit computer and the USB of my computer at the USB interface and that this should be fine (that with the shared ground then the microcontroller will be able to properly read the voltages off the peripheral bus).
I have heard of ground loops happening and I am just wondering what my risk would be here (I don't think it is an issue in this case but I kind of want to ask)
Thanks!


texts: Flatness vs Frequency parameter in RF zero bias detectors

texts:
I require the measurement of RF power from a port, and I am considering using a zero-bias RF detector in order the measure the power being delivered through the port.

These devices give a voltage output which is roughly linear to the logarithm of the power being received at the port, ie., power in dBm.

All these detectors have a parameter known as Flatness vs. Frequency, and they mention the values in dB. I think that this may be referring to the amount of change of the output voltage as the RF frequency of the input power is changed, but I am unable to figure out how it works quantitatively, and whether the deviation is sufficient for my application.

For example, one of the detectors which I am considering shows a flatness vs. Frequency of (+/-)0.5 dB max. What does this mean, and how can I make sense of these numbers?


texts: How to isolate I2C bus when Master is being programmed?

texts:
I just asked this question trying to find out if having a powered I2C slave in an ISP bus during MCU (Attiny) programming would be problematic. Apparently it would, so I need to isolate the slave(s) from the bus temporarily.

I can't just power down the slave(MPU-6050) because its inputs are not tolerant to 3.3V when its Vcc=0V.

I also found this interesting related question, but the solutions proposed do not work for me (I have limited board space and specific ICs availability are a problem for me for this projects budget).

I'm really trying to steer away from a jumper/DIP switch solution so I'm considering active ones. Here it goes:

Use a discrete bi-directional level shifter

But instead of a High and Low voltage side, I'd try something like this:

simulate this circuit – Schematic created using CircuitLab

When Attiny is programming, its outputs are high-impedance, R5 turns M3 off. C1 is mainly to prevent glitches on the pin from turning M3 back on again.

R7 then turns M1 and M2 off, and SCK/MOSI can "bounce" freely without disturbing the I2C slave(s).

Upon booting, the Attiny turns M3 on, providing power to the I2C bus.

Would this work? Am I overlooking or overcomplicating something?


texts: what is the specific reason for using FIFO in asynchronous domain at VLSI?

texts:
I was wondering that the reason of using FIFO in asynchronous domain at VLSI.
Basically, to prevent x propagation in asynchronous domain(aka CDC domain), I was taken care of 2 stage F/F method for resolving issue.
I think I can use the same Idea to the multiple depth data path.
but People still using the FIFO in CDC domain why?
I want to know what is the specific reason for using FIFO in Clock Cross Domain.


texts: requirement of current drive for MOSFETs

texts: BJT is a current controlled device and MOSFET is a voltage controlled device. but then, why gatedriver ICs are required for MOSFETs??


texts: How can I calculate the power dissipation of an IC from datasheet values?

texts: I have to make a circuit using ICs on a PCB. But before that, I want to calculate power dissipation of IC. So, I saw datasheet of 7400, and it gives me an input voltage, supply voltage, input current and output current. But I can't recognize what is needed for the calculation. How can I calculate power dissipation? Or is there other information I have to know?


texts: Adding a router (no key) to an encrypted Zigbee network

texts:
Backstory:
I'm looking to extend the range of a proprietary wireless system.

From looking at diagnostic data I think it uses a 2.4GHz ZigBee network, propably Mesh configuration. It might not be encrypted, but I'm wondering about the case if it is.

I have not looked at what's going on the waves, nor do I have any ZigBee modules/tools yet either.

Question:
If the ZigBee network is encrypted and I do not have the key, is it possible to add a router without the key to the network.

From digi.com kba on encryption I understand that it is possible for an unencrypted node to join an encrypted network, but it will see "garbled" (encrypted) data.

What I'd like to know is if it is possible for that node to relay the encrypted data to an end device that knows how to handle it?


texts: Atmega328P is not responding in avrdude using usbasp

texts:
I have a cheap Chinese USBASP clone and it works fine with my ATtiny13A, but I always get this:

avrdude: auto set sck period (because given equals null)
avrdude: warning: cannot set sck period. please check for usbasp firmware update.

This is not actually a problem, because I successfully programmed my ATtiny13A several times, also using a -B 250 argument when my fuses were set to a lower clock speed, so my USBASP definitely works.
But now I want to program my ATmega328P and I get this:

avrdude: auto set sck period (because given equals null)
avrdude: warning: cannot set sck period. please check for usbasp firmware update.
avrdude: error: programm enable: target doesn't answer. 1
avrdude: initialization failed, rc=-1
     Double check connections and try again, or use -F to override
     this check.

I do not know what the fuses are of this chip, I changed it some time ago and now I can't even read them. I tried to connect a crystal to the atmega, and I also tried without any crystals and nothing worked. Can this chip be dead? I don't think I applied high voltages to it.
(How) can I fix it?
Please help me.


texts: Patching stereo audio into an old car's tape deck

texts:
I drive an older car before the days of 3.5mm line-in jacks. A couple years ago, I found an interesting idea online where some owners of the same car patched in a line-in directly into the L/R channels of the cassette player deck (since no one really uses cassette players anymore).

http://www.matthewsvolvosite.com/free-ipod-input-for-your-volvo-radio.html

I did the same thing, and it seemed to work great for a couple Nokia phones that I had and also an old iPod shuffle.

Recently, however, I got a new phone - the Samsung Galaxy S III and it seems that it doesn't like the line-in at all. When the tape deck is powered off, the phone detects the line-in properly (e.g. it shows that headphones are connected, and any audio is routed to the headphone jack; of course there is no sound played in the car because the tape deck is powered off).

However, once I power on the tape deck, the phone detects that there is nothing connected to the headphone jack.

Oddly though, if I start playing a song before powering on the tape deck, then the phone maintains the connection when powering on the system and the music plays fine through the car's audio system. However, the moment the song ends or play back is stopped/paused, the phone thinks its no longer plugged into anything again.

Curious about this, I assumed that perhaps there's something odd with the grounding of how I hooked up the cable's wires the first time. The PCB I patched into had a labeled terminal for Left and Right, but none for Ground - so I had just grounded the cable to the chassis (for better or worse).

In opening up the stereo system again and checking with a volt meter, I noticed the following:

When the tape deck is powered on, there is a 2.8 V potential between the signal lines (e.g. L or R) and ground
When the tape deck is powered off, there is a 0 V potential between the signal lines and ground (I suppose that would make sense; but what about the first bullet point?)

Interestingly:

The potential between the signal lines and ground of the 12 V outlets in the car also show the same 2.8 V potential
There is a 10 V motor in the tape deck - its ground also shows a 2.8 V potential from the audio signal lines

When I play music through the system using the method described above (where I "trick" the phone into keep the connection), the potential between ground and signal is something less than 1 V (close to 0 V when measured with a basic multi-meter).

I thought perhaps I needed to add some pull-down resistors to the signal lines, but I'm not sure if this is true? I tried this with a couple different resistor values (680 Ohms and 10 kOhms) but neither seemed to have any noticeable benefit (the difference was still greater than 2 V).

I was wondering if anyone had any ideas about this?


texts: What could happen if I touch a constant current source for example 5 Volts 1 Amp..?

texts: Yes, I am talking about a constant current source not a voltage source. Would the 1 Amp go to my body?


texts: Can an inductor/capacitor/resistor combo emit the same frequency as a given crystal oscillator?

texts:
Beginner in electronics and radio frequencies in particular interest me. That said I'm having trouble understanding what components are used when. When I initially searched about radio frequencies, most knowledge articles said those frequencies are produced based off of a crystal oscillator that'll oscillate at a specific frequency.

However, in some DIY FM transmitter tutorials I've looked at a lot of the circuits don't incorporate any crystal. Rather, the circuits incorporate certain capacitors, and a coil (inductor?).

In this case are they doing more or less the same thing? For example, if I had a crystal oscillator generating a frequency at 88.1 MHz.. could I create an equivalent circuit using capacitors & a coil that also produces an 88.1 MHz signal? If no, why not? If yes, is there a reason to use one over the other?

Appreciate any responses.


texts: Calculating DAC samling rate from datasheet

texts:
I want to use the DAC121S101 DAC (attached) and was wondering if my sample rate calculations are correct.
Settling time is 10uS which means max sampling rate would be 1/10us= 100KHz, 100KSps
But need to look at digital side as well. Max clock rate is 30MHz and it is a serial interface. Need 16 bits for 1 sample so 1/30MHz * 16 = .53uS or 1.875Msps
So do I use the smaller rate of the two numbers above (100KSps vs 1.875Msps) which is 100KSps or do I need to divide 100KSps/16 = 6250Kps?
Thanks!
DAC Datasheet


texts: Why doesn't the gate voltage drop entirely across the oxide in a MOS capacitor?

texts: As the title says, for a MOSCap with, say, a p-doped semiconductor substrate, when a gate voltage \$V_{g}\$ is applied across the gate and the grounded substrate, why doesn't \$V_{g}\$ drop entirely across the oxide or why does there have to be a non-zero potential at the oxide-semiconductor interface?


texts: Soldering tab terminals without using holes

texts:
I cannot find any information about a practical problem I encounter.

If we don't have crimping tools, when soldering wires to tab terminals with holes as below:

Do we need to pass the wire through the hole before soldering?
But sometimes the wire is much thicker than the hole, in that case is it fine to solder the wire tip on the tab terminal's surface?

I couldn't find any examples about this.


texts: Can we make a simple wireless device by mutual induction phenomenon

texts:
I want to make a simple wireless device (radio?) that consists of only two copper coils where changing magnetic flux in primary coil causes a current flow in the secondary. I tried, once, with LEDs and 3-Volt DC batteries, but failed.
So any insights or plans are appreciated.
I would also like to give it some range (like, 2 meters).

Moreover, how would this device of mine will be different than a radio? Because, to my understanding, the changing flux here also causes electromagnetic waves to travel away from the coil. So does this mean that the basic principle behind the both is same?

My own knowledge about all this, as this writing would suggest, is very limited. I could not find any designs or schematics on the internet simple enough to follow and understand. Any help therefore is appreciated.


texts: Unable to install MCP2221 Driver on Win10 64bit OS

texts:
I use this PIC32MZEF board - https://www.microchip.com/DevelopmentTools/ProductDetails/dm320007. It needs MCP2221 driver tobe installed for uart communication with PC.
I downloded from official website.

But it throws following error . "The current language is not supported by the Device Driver Installation Wizard. Contact the vendor that provided you this package."

I asked microchip support team and got to know that MCP2221 Driver is pre-installed with Win10 OS. But when I connect USB, No virtual Com Port created.

Very similar issue was faced by @Doug12745 in this post. He was at-least able to install the driver back then. There is no proper answer for this question yet. So please reply if anyone know solution.


texts: Floating Nwell schematic and introduction in a MOS switch

texts:
My classmate told me using a mos (body connect drain)as a switch may have leakage current,because there is a parasitic diode in that MOS,so there will have a leakage current.so i have to connect the diode to the higher voltage,but the voltage of source and drain will change,and my classmate told me the floating Nwell will  help me.

However,after finding some information,i found the floating Nwell is the related to the processm,not the schematic,so i want ask can anyone show me the floating Nwell schematic and introduce it to me?thankyou


texts: SMALL BOX Solution - To control/reduce power consumption in household electrical appliances?

texts:
We use multiple power sockets to power different house hold electrical appliances like.. AC, Refriegerator, Television and Other Electrical Appliances. I want to turn on/off their power supply/consumption during specific time of the weekday/end or when I am not in house.

A socket similar to female socket at home, that can be controlled/programmed based on the requirement like : 2-4 PM ON and then 4-6 PM OFF on any given day in a week.
It should be smart/intelligent switch in a SMALL BOX, so that it can be taken from one power socket to other power socket based on the user's requirement to control the power consumption in appliances A, B or C.
It should be user friendly enough so that a layman should be able to program the logic to turn on-off based on the requirement.
solution should be cost effective/efficient and durable.

Can anyone please help me suggest a design/solution to this?

I know it can be controlled/programmed through uC, but do not know about electronic circuit and its interface to uC etc..


texts: Do we connect the ground rails on both sides of a SMPS?

texts:
Is there any reason for, or not for, connecting the ground of the high voltage DC line with the ground of the low voltage DC rail(s) across the transformer in a switch mode power supply (SMPS)?

I've seen that it is common for a single low charge capacitor to be placed across the transformer of a SMPS to connect the two ground planes (presumably for noise cancelation), but I'm not sure why you wouldn't connect the grounds like you would in most other circuits.


texts: Below is a circuit for a 4 digit 7 segment display, common cathode as well as multiplexing, I need to make improve upon the circuit. Based on research I know that the 4 Pull-up resistors R2, R4, R6, RR8 can be removed. What I need is a detailed explanation as to why to help me understand this better. I'm an electrical engineering student so go SLOW


texts: I am using Xilinx ISE design suite for simuation of my Digital Circuit. I want to model delays into each individual element of my combinational circuit during simulation. I don't want to explicitly add delays into my module as it will bias my circuit. Is there a way?


texts:
I'm really building a sort of Rube Goldberg machine that students will assemble in order to guide a falling ball down through a series of gates/openings, where I need to detect when they're successful in making it through one of the gates.  My plan is to hook each gate up a Raspberry Pi in some way, though I'm not 100% sure what components I should/could use.

Are there any electrical components/breakout boards/ideas I could use to detect large marbles falling through a gate/pass?  I've been debating on using a phototransistor and some LEDs to detect when the LED light is interrupted, thus signalling the passing of the ball, but I didn't know if there was a better and simpler solution.  Maybe some sort of gate that won't mess with the marble's trajectory?  A light or motion sensor?  Something that can quickly detect the marble's presence?  Some sort of trip wire?

For reference, here are the magnetic marbles that I'm using.  I'm using a Pi Zero too.


texts: What does a shift in time domain do to the phase in frequency domain?

texts:
Suppose \$y_k = x_{(k-m)}\$, i.e. \$x\$ is a time shifted version of \$y\$.
Then the Z transform of \$y\$ is \$z^{-m}X(z)\$.

What does multiplying by \$z^{-m}\$ mean in terms of the phase response of \$X\$ for a negative shift? A positive shift?


texts: Is there any less awkward way of saying "response to to a step change in the amplitude of the input waveform"?

texts:
Exactly what the title says. I'm writing a technical report on a project I'm doing and I have one circuit which takes in a sine wave of various amplitudes, does a bunch of stuff to it and produces output that's steady for a steady input wave amplitude.

I'm tempted to say "step response" but in isn't that strictly speaking. And "response to to a step change in the amplitude of the input waveform" just sounds super awkward and too long to be using all the time while referring to the responses.


texts: Firmware reliability for over temperature detection

texts:
I am speaking about an industrial equipment that is generating gas. It is under certification test (CE marking) IEC 61010 in a third party lab.

In the device there is an over temperature detection mechanism, which is aimed at stopping the device. Here is how it works:

Temperature sensor (LM335)
A uC is reading the temperature every seconds
After reading it compares its value with a hardcoded threshold, and if temperature is over the threshold, it raises the alarms and launches the stop procedure.
In a couple of seconds it goes in stand-by mode.

The lab making the certification tests tells us that it since the over temperature detection is made by mean of software, it is not reliable. And because it is not reliable, it is not compliant with CE Marking.

They also add that "It is considered by the testing labs that a software is all but a reliable component. Non exhaustive list: infinite loops, data corruption, EMC perturbation ..."

It sounds completely extrapolated to me.

Is the testing labe right? Are software/firmware considered as not reliable?
If no, how shall I prove the lab that we designed our firmware component to be reliable?


texts:
I am reading about antenna design and have a few questions which I could not get clarified.

I read about "Stubs". I got to know that Stubs are used for impedance matching of an Antenna either by leaving it as an open circuit in one end or as an short circuit.

Question - How to find the input impedance of an Antenna of a particular length? Is there any method and how to calculate the stub length? Is there any formula?

Would really help me if someone could provide an example for calculating the input impedance of the antenna and the stub length for impedance matching


texts: Calculating values for compensation network (boost converter RC+C network)

texts:
I'm trying to build a boost converter with current mode PWM control, but I'm stuck at selecting capacitor and resistor values for compensation. I'm using a LT1619 as the controller IC:

simulate this circuit – Schematic created using CircuitLab

Datasheet: LT1619

Boost converter parameters:
\$V_{in(min)}=2.7 V\$
\$V_{in(max)}=3.6 V\$
\$V_{out}=5 V\$
\$I_{out(min)}=0.5A\$
\$I_{out(max)}=1 A\$
\$f(switching)=31250Hz\$
\$\Delta I(step-min)=50mA\$
\$\Delta I(step-max)=200mA\$
\$Overshoot\;step\;load\;error:100mA\$
\$V_{dc(error-tolerance)}=10\%\$
\$V_{out(ripple)}=90mV\$
\$V_{noise(max)}=50mVpp\$
\$Minimum\;phase\;margin\;at\;a\;again\;of\;unity: 8\%(from\;overshoot)\$
\$Operating\;temperature\;range:-30\;degrees\;celsius...+120\;degrees\;celsius\$
\$Capacitor\;tolerance: 10\%\$
\$Inductor\;tolerance: 5\%\$

The problem is that I do not know how to calculate the capacitor and resistor values. I know that the feedback network is a complex aspect and it's not easy to understand, but I believe that if someone explains this to me from 0 to top (a thing which online sources apparently fail to do) then I can comprehend it.

But, I don't know, there might be too much to explain. I would appreciate if someone could provide a basic explanation and then point me to a document from where I can learn if that's the case.

I think this is all the needed information, but if more is necessary, then I'll be ready to post it.


texts:
Things to be kept in mind :

The sensor would be placed under a thick layer of cotton.
The sensor should be able to withstand high impact.
The sensor would be connected to an Arduino.


texts: 3 phase motor change from 440 V to 220 V with diagram question

texts:
Some confusion the way my new machine is wired.  I bought a sander not hooked up and the guy thought it was wired at 440.  I need to set it to 220. The motor says 220/440.  I have 220 at my shop with a phase converter making a 220 leg that runs other 3 phase equipment.

Currently the Motor has two sets of 3 wires feeding it.

One feed leg 1a mates to U1, one feed leg 1b to V1, one feed leg 1c to W1.  W2 mates to W5, V2 and V5, U2 to U5. As the drawing shows lower right. But W6,U6,V6 are not mated together as I see in the diagram, rather the second feed set of wires are attached. Leg 2a mates to W6, Leg 2b mates to U6, Leg 2c mates to V6

Why are W6,V6,U6, not attached and rather attached to the other feed wires?  He said the machine was running.
How do I configure this to 220V?

Here is the plate.

There is a control panel on the machine that handles the power going to the motor, I assume in a timed fashion for the start and run power.  There are 2 sets of wires feeding the motor.  L1 L2 L3 and another set of L1 L2 L3 both coming off mechanical relays.  I think one set feeds the start and then the other set feed the Run but just a guess. The old owner called me today and said it was/is wired at 440.  I have a hard time understanding the schematic to wire it to 220.

If I connect the DELTA
L1 to U1,U5,W2,W6
L2 to V1,V5,U2,U6
L3 to W1,W5,V2,V6

That uses all the 12 motor wires and 3 feed legs.
What do I connect the other 3 feed leg wires to?


texts: How to interface IO Link devices without any gateway/additional circuit

texts:
I am planning to use a distance sensing device like this distance sensor with a mini computer like the Raspberry Pi or the Jetson boards. I read that the interfacing requires additional gateway like this.
Due to the reasons like cost saving, etc, is it possible to avoid this gateway... such that the analog output of the sensor can be interfaced directly with the mini computer ?


texts:
What is the correct definition of the LSB voltage for an analog to digital converter?

I have found two formulas:

LSB = FS / (2N)

LSB = FS / (2N - 1)

N ... resolution in bits of the ADC.

FS ... Full scale input range

Has this anything to do with the location of the first code transition?

Can someone clarify this problem for me?


texts: Trying to work out reverse saturation current for diode using shockley diode equation

texts:
Hi, everyone I was wondering if I anyone could help me out I am trying to work out the reverse saturation current for the a diode. The attached photo shows how I have rearranged the formula in terms of reverse saturation current. I dont know what I am doing wrong I keep getting really small answers such as ^-19 small and ^-85 are answers I have had.
P.S the VD value is 5V as thats the supply to the circuit.
Any help would be really appreciated. Thanks in advance.


texts:
I have a microbit setup with a relay controlled by pin 0. The relay is being used to turn on a simple motor. Everything works fine when the motor is connected to a separate 3v power source, but if I try use the gnd and 3v outputs of the microbit to power the motor the microbit immediately resets once the relay switches on.

These are my connections to the relay:
Microbit 3v > relay DC+
Microbit gnd > relay DC-
Microbit p0 > relay IN

This fails:
Microbit 3v > relay NC > relay com > motor > microbit gnd

This works:
 3v battery + > relay NC > relay com > motor >  3v battery -

I have tried adding a resistor in the path, but the smallest I have is 170 ohm which is too much to power the motor.


texts: Why is the BJT in this circuit in active mode?

texts:
I don't know why the BJT is in Active mode ant not in saturation mode.

My calculations are:

$$V_{TH} = 10 * \frac{10}{10+12} = 4.54V$$

$$R_{TH} = \frac{12*10}{12+10} = 5.45k\Omega$$

$$V_{B} = V_{TH} - 0.7 = 3.84V$$

$$i_{B} = \frac{V_{B}}{R_{TH}} = 0.7 mA$$

$$i_{c} < \beta i_{b}$$

$$2.48mA < 70mA$$

I don't know where I went wrong in my calculations

Edit: Forgot to add iC calculation

$$i_{C} = \frac{10 - 0.3}{3.9} = 2.48 mA$$


texts: Is this the correct way putting multiple chips into one JTAG chain?

texts:
I am thinking about a hobby project that have a microcontroller and a CPLD connected together. Is this the correct way doing it?

simulate this circuit – Schematic created using CircuitLab

Secondary questions:

Is there any "standard" pinout I should follow when designing the JTAG connector?

Altera CPLD and ARM microcontrollers have very different semi-standard JTAG pinouts. Can I settle on something that is somewhat a standard that can be convenient in both environments? I am thinking about the CMSIS-DAP pinout (a standard used in ARM world) with the nTRST line routed to pin 7 (otherwise unused on CMSIS-DAP,) but subconscious told me that the Altera FPGA pinout may be better as USB Blaster can also be used in OpenOCD.
How to debug both chips at once, if it is even possible?

Since I got both chips in the same JTAG chain, in theory I should be able to debug both chips at once. How to do so in practise? I know that OpenOCD+GDB can work for the ARM, but what about the CPLD?

Also, in this arrangement, should I avoid SWD on ARM at all?
Is it a good idea to share clocks between the two chips?

As suggested in the diagram, is it a good idea to clock the CPLD using the clock output feature of the MCU? How to keep EMC managed in this scenario?
What is a good bus interconnect for the two chips?

Since the chip in question is fairly large a package, I can hook the CPLD off the exposed SRAM interface. Is it a good idea? Should I also hook up the I2C and SPI buses? And a few extra pins too?


texts: How to Implement a Remote Control Trip Switch (circuit breaker) for 80-100A 12VDC

texts:
I need to be able to remotely trip a circuit using a signal. The circuit can and regularly does carry around 80A or more @12VDC, but the trip would not be expected to (actually would be designed specifically NOT to) open or close when any significant current flows...at switching it will be 1A or so, max. Ideally I would have the trip-off happen digitally, but the reset should be manual, hence why I say a trip switch, not a relay. Also, for that kind of current, trip switches seem far cheaper than relays.

To be clear, I don't need the trip to happen on overcurrent as per usual, only on a signal, but I could spec it to trip far higher than would ever happen. But is there such a thing as a remote-control tripswitch? I can't seem to find one on Farnell. Or is there another alternative component that would do the job satisfactorily?

Another alternative would be a servo or solenoid and a standard trip, I guess, but I'd rather not do much mechanical engineering if avoidable!


texts: How is the power dissipated equal to heat generated in an electric circuit?

texts: I am told that P=VI and then I'm told Heat generated is equal to VI*time. does it mean that all the power is heat energy


texts: I want to use the BER result of a turbo coded system from an article, but my system is not BPSK (and the article has discussed just the BPSK case). Now I wonder is Turbo decoder, modulation dependent?


texts: How do I Avoid Very Long Horizontal Signal Path "Snakes" in a Schematic?

texts:
I'm drawing a schematic for my DIY project, a RF mixer, it has a local oscillator followed by a bandpass filter, a voltage divider, eventually the signal is fed into a mixer.

Unfortunately, even before I manage to finish the LO port, the signal path on the drawing becomes very long ("snake syndrome?"). The mixer is supposed to be the center. I expect it to be even more difficult to manage, as the RF port and IF port would also have their own impedance matching and low-pass filter, both will be long snakes. It will make the schematic very unbalanced.

I know hierarchical schematic is a solution: you show all blocking blocks as blackboxes, and then "expand" each blackbox separately. But there should be a way to achieve the same result in a non-hierarchical way. What is the industry standard to show the long signal paths in a reasonable way?

LO:

Overview (RF and IF would also be snakes when finished):


texts: Switch to use in high g-force environment?

texts:
I need an on/off type switch (spst) on a device that will be subject to high, continuous centrifugal force loads (500-1000G or 5000-10000 m/s2)).
Will your everyday, off-the-shelf switch handle this?

Are there certain types of switch (sliding, toggle, push on/off) that will likely handle the forces better?  It seems not many datasheets have such a rating.

I'm interested in both quantitative and/or experienced-based answers (i.e. "here's a datasheet" or "well, I've used this  in this situation before").  EE Stackexchange seemed like the best place to ask this.

EDIT: The switch will be used to turn on/off a wireless data device.  The switch will effectively just be pulling an enable pin high, so it's handling 3.3 to 5V, 1-10mA.  My concern rests mostly with undesired switching on/off due to the forces involved.  Am I unduly concerned?

EDIT: I talked with a friend, and she happens to be involved in rocketry - another electronics in high-G situation (although 50-100G are more typical).  She mentioned that for switches, Rotary, screw, or just twisting the wires together are considered reliable.

I'll probably go with a screw switch unless someone suggests something else.


texts: Pull-up scheme for Hall effect sensors on a BLDC

texts:
I looked around on here, and used google, and couldn't find a direct answer to this question.  Please forgive me if I overlooked something.

I am working on a board to control a BLDC motor (BLWS231D-24V-2000) which has a set of integrated Hall effect sensors that I will be using in conjunction with an external capacitive encoder (AMT102-V).  I will be powering the sensor with +5V coming from the Driver IC (TI DRV8323SR) I am using.   Through conversations with an application engineer at the motor manufacturer, I learned that when the Hall effect sensors (open collector output) are floating, I "should" read about 6.3 V, if I were to hook them up to a scope.  The MCU (XMEGA128A4U) I am planning to use operates on 3.3 V logic.  Before learning about the approximate voltage from the Hall sensors in their floating state, I was planning on using a pull-up resistor to the 3.3 V supply line that will be coming from a separate linear regulator to drive the floating voltage to the logic voltage for my chip.

My question:

Should I set up a resistor divider circuit so that the floating voltage from my Hall sensors is forced to be at or near 3.3 V, or will using the pull-up scheme shown above work?  Or should I be looking for a different solution to the voltage issue all together?  Or is there an issue?  I don't want to damage any pins on my MCU and have to completely re-design the board.  This is my first experiment with hall sensors for motor control.


texts:
I have a USB device that perfectly works when it's plugged into a Tower Windows-PC, but doesn't work when it is plugged into an old Linux Laptop. Is there a way to add more power to the USB device? Would the following circuit work?

simulate this circuit – Schematic created using CircuitLab


texts: Designing voltage to current converter 4-20 mA

texts:
I'm currently designing (or at least trying to) a RTD amplifier with ICL and current outputs.

What I've got so far is a working RTD and ICL schemes, but I still struggle to design a proper converter. The main issue is that the load impedance can reach up to 600 Ω. Input voltage range doesn't really matter, I can deal with that by adjusting my RTD, but as a complete amateur I have no idea how to design such a converter. I've already found one solution that I like on Stack Exchange, but even though in theory it should tolerate up to 1100 Ω, it clearly doesn't.

Here's a link to the topic I'm talking about:

Also, for the curious people (to actually confirm that I'm a complete amateur in electronics), here's what I've got so far:


texts: Trying to increase resolution of ADC using an op-amp

texts:
We currently have a circuit measuring a thermistor in a water tank, passing through a couple of voltage dividers and then plugging into an 12bit ADC which eventually interacts with a microcontroller and solenoid to help regulate a cooler for the water tank temperature.
The problem is that while currently our 12bit ADC operates between 0-5V, the temperature of the thermistor is only fluctuating between 8k-12k (between 20-30degC.) This means we are only really using 1.3-1.6V of the range of our ADC, and missing out on a ton of potential resolution.
I was hoping we could figure out how take that .3V difference in our current range, and using something like an op-amp to magnify it and have a range between 1-4V, but so far I have only been able to increase the resolution by 2-3x or so that way.
Am I way off track here?  Is there a better way to accomplish what I am trying for?  Still have a lot to learn and could use some insight.


texts: Calculating MOSFET gate current at certain PWM frequency

texts: I want to power the gate of an IRLB3034 MOSFET by a PWM output from an arduino. I know that the current required to charge the gate increases, the higher the switching frequency is. With 5v powering the arduino, and a 490Hz PWM signal, what will the required current? The max current from an arduino pin is 40ma, will I need a transistor to power the MOSFET gate? The MOSFET will only be switching a 2A load.


texts: What is the shortest possible *channel length* in a currently available commercial CMOS process?

texts:
I'm aware that terms like "5 nm", "7 nm" for the latest technology nodes no longer refer to any linear dimension of the transistors, although I have seen some interpretations in terms of pitch. My understanding is that the names are arbitrary and just following what the naming convention used to be when they really did correspond to the gate lengths. As far as I can tell, a new process is defined according to milestones in achievable transistor density.
For these 5 nm, 7 nm, etc. processes, what is the actual shortest allowable channel length? Though new transistors look very different from the CMOS devices from 30 years ago my understanding is that there is still a definable channel length if not a clear gate length equivalent (e.g. for FinFETs).


texts: Need help to identify potentiometers, please

texts:
I have to replace some scratchy potentiometers used as volume potentiometers in a Rocktron Velocity 300 guitar power amp from the early 1990's.

These two parts are labelled:

15A100K 9252
TØB10K 9303

Does someone have some informations about them or a source where I can get information?

Edit: I've found schematics for the Velocity 300:


texts: Calculating minimum trickle charge power requirements

texts:
I'm looking to buy a solar panel to trickle charge my phone + other devices while out and about. Obviously I don't want a panel that is excessively large/heavy but also I want something that won't allow the battery to drain even after potentially many hours of usage (not just idle).

So is the following a method of working out how much power I need?

I know from experience that using the satnav on my phone the phone will last at least 2 hours from a full charge.
If I also know that the phone can gain a full charge from empty in 2 hours when powered off by using a 5v, 1amp charger. Does this mean I can simply half this power requirement to retain whatever charge level the phone currently has indefinitely?

Or more generally can I apply this formula:

Pc    Pr
-- =  --
Tc    2*Tu

where: Pc = power output of charger,
Tc = time take to charge from empty in powered off state,
Tu = time to full drain battery from full when in required usage scenario.
Pr = required power to maintain a usable charge level indefinitely.

Obviously in reality I'd probably add a 10% error/safety margin.

Thinking about it I'm pretty much sure that the 2 in my formula is wrong. Also I'm wondering if there is some overhead on the charger. i.e. a minimum power level required before charging even starts.
Also I'd probably have to add an overhead for any required voltage regulation etc.


texts: How can I share a 900 MHz antenna between two radios?

texts:
everybody.

I have an already working ZWave radio on my PCB. It has a PCB antenna and it's working perfectly. I need to add the Si4362 Low Current Receiver
which is a receiver for the bands from 142 to 1050 MHz to my device.

Due to constraints in the PCB size and the fact that modifications to the enclosure are pretty much impossible at this stage of the project, I need to examine the possibility of sharing the PCB antenna between the ZWave transceiver IC and the Si4362 Receiver-only IC.

I took a look to the question Sharing antenna between receiver and transmitter but it deals with the fact that they are separate receiver and transmitter both for 433 MHz and the answer states that the antenna could be connected directly to both wich I don't think applies to my use case.

Also in the question Shared antenna on multiple 2.4Ghz receivers the answer suggest a power divider or splitter, but I don't need to just split the signal. I need to be able to switch between the two radios to decide at run time wich radio will use the antenna. Fortunately, both don't need to be active at the same time.

Also, I can't use chip antennas because ZWave doesn't allow that.

Does anybody know how to achieve this?


texts: How can i calculate forced response of \$ V_c\$ across the capacitor used transfer funtion?

texts:
$$ v= |V| u(t) \quad [V]$$
u(t) is :  t<0 and 1 to t>0

\$ i_L(t) \$ = inductor current
\$ v_c(t) \$= voltage  capacitor

This is the transfer funtion : $$ \frac{sC}{1+s^2LC} \\ w= \frac{1}{\sqrt{LC}}
$$
How do i find \$ a_2 \$ constant of \$i_L\$?

Transient response : \$ i_{nL}= a_2 \sin(\frac{t}{\sqrt{LC}})\$

Then to calculate forced response of \$v_c\$   across the capacitor used the same transfer funtion, What do i do ?


texts:
I have this schematic. My problem is it only turns the motor when I supply the 5v to the right transistor (Q2). I remove the 5v and put it on Q1 and nothing.  I've replace all parts and still does the same thing.  FQP27P06 has an Rdson at -10V, RFP30N06LE has Rdson at 10V.  Is there something I am doing wrong?

simulate this circuit – Schematic created using CircuitLab


texts: Timing loop in finite state machine sync

texts:
I'm creating a FSM in VHDL to implement a serial transmission module. However, whenever I synthesize it, it throws  a bunch of the same error about finding a timing loop.

[Synth 8-295] found timing loop.

However, the line it points to looks like this:

sync_proc : process (sys_clk, sys_rst, NS)
begin
    if (sys_rst = '1') then
        PS <= FSM_RESET;
    elsif rising_edge(sys_clk) then
        PS <= NS;
    end if;
end process sync_proc;

Specifically, the error points to the "PS <= NS" line. From what I've been taught and read in VHDL standards, this is a standard way to implement the synchronous part of an FSM, but I can't find why its giving me an issue about it now. Any thoughts?


texts: I have more than IZK current running through a Zener diode, but the voltage drop is below its Zener voltage, what does this mean?

texts:
I'm supplying more than enough voltage, I am however using a transistor which may have complicated issues. The voltage drop should be at least 4.1 for that diode. Having problems with multiple models regardless or what resistance is set. Have I just connected it incorrectly?

https://postimg.cc/5Xnv181d