texts:
Noob here, with a basic question.
I am looking for a switch to close a circuit not straight to ground. P channel MOSFET seems fitting, but I would like one where to keep the switch open, it does not consume power.

My problem in more detail:
I just redid a battery powered arduino project incorporating a wake on shake from sparkfun. It is a 5V node, used to be on a 6V battery, that I now replaced with a 3.7V and I am regulating to 5V for the node. I had battery level reporting by having two resistors hooked up to an analogue pin to ground pin and raw pin respectively. Now, I would like to do the same for battery (connect the 3.7V positive to the same pin with a different resistor), but not constantly, only switch this circuit on by the arduino at certain intervals.

Please, point me in the right direction, how to best tackle it.
Thanks,


texts: What kind of motor is this? Looks more like a solenoid than a motor

texts:
I was going through a large box of random motors I got at a yard sale. I was sorting them for use in later projects when I came across a motor I couldn't classify. Long story short, the magic smoke left so I figured I would open it up.
What I found didn't seem to make sense to me. There are two separate stator coils, which I had predicted from my multimeter. But they run around the rotor, not up and down it. The only thing I can liken it to is a solenoid, so I'm confused how this would work as a motor. Also I couldn't find anything with the motor's part number aside from some eBay listings which don't help.


texts: "ground disturbance" in current sensing with shunt resistor

texts:
There are lots of questions about "traditional" low-side current sensing using a shunt resistor.

Most discussions and papers mention the drawback of "ground disturbance" introduced by the measurement principle (dropping voltage across the sense resistor).

Why is that usually a problem? Assuming that the sense resistor is only a resistance (neglecting parasitic inductance) and assuming the voltage drop is low enough to not brown out the circuit, the "circuit under test" will not see any influence from outside?

Am I right in the assumption, that ground disturbance is only a topic if the circuit under test is somehow interfaced to other circuit parts that assume a common ground to the circuit under test (e.g. some digital interface such as SPI)?


texts: Effect of Schottky diode capacitance for LM2596-based buck converter

texts:
I select a schottky diode to output a DC / DC converter.
Found several SMD SS52 options. One option has a capacity of 800pF, the other 200pF.
The smaller the capacity, the better? The version with 800pF has smaller overall dimensions, which is attractive, but the issue with capacity interferes.

There is also a reverse voltage issue. There is an option for 20V, there is for 200V. The voltage of the circuit to which the diode will be connected is 5V. Can I choose 200V without harm?


texts: Why it was not possible to use 256-QAM in the past

texts:
What is behind the progress of speed in digital communications? For example going from analog modems to high-speed DSL/DOCSIS on the same old metalic lines...

Why wasn't for example 256-QAM possible before 15 years? What is the difference between 16-QAM and 256-QAM (or even 2048-QAM as mentioned on wikipedia) in this regard? I understand that it needs better SNR / sensitivity to distinguish between all the values, but we are somehow able to get that on the same old cables.

Is it that the math for this was too complicated? Or it was not possible to manufacture components which would meet the computed specs? What parameter was problematic? If manufacturing was the issue, what new invention / technology helped?


texts:
I am currently a 3rd year undergraduate electronic engineering student. I am doing a course in signals and systems and I am struggling with a few concepts regarding Fourier Analysis. The textbook we are using is "Linear Systems and Signals (2nd Edition)" by B.P. Lathi.

I have managed to practice the realisation/implementation of a transfer function (from chapter 4 of Lathi) and I seem to be fine with the DFI and DFII realisations, but I have no idea on how to obtain the implementations using op amps (example 4.22, attached below).

Detailed explanation and steps on how to obtain the op amp form of the given transfer function would be greatly appreciated.


texts: How do I apply mosfet switching to this battery circuit

texts:
I have this circuit:

The circuit consists of a charging voltage (C+=42V,C-=0V), ~42V battery(B+=42V,C-=0V), and a low side mosfet switching circuit with an output P. When SW1 is connecting C and B, there is 42V across P, and when SW1 is connecting A and B, there is 0V across P.

What I would like help with is the following.

I want this circuit to operate such that when the charging voltage is connected across the battery, the circuit is put into a state where there is 0V across P, regardless of the state of SW1.

I think I would use a mosfet switch in series with R1 and SW1-C that opens when C is applied and closes when C is removed, and another mosfet switch in parallel with SW1-A and SW1-B that closes when C is applied and opens when C is removed.

I have tried various combinations of P and N mosfet switching circuits in LT spice, however I cannot get it to work how I would expect.

Does anyone have any suggestions of a way to achieve this using mosfet switch circuits?


texts: What types of Shielding and Filtering would allow devices to be used in a MRI environment?

texts:
I'm working on a respiration monitor and I was wondering what area of electronics I would need to get familiar with to design the hardware filters that would stop the RF/EMI from frying the system.

The MRI we are working with is actively shielded so stray magnetic fields are not as harsh out side of the magnet but we are still going to run cables to the patient inside of the MRI. The signal distortion is not much of a problem, we have the algorithms that can filter the interference.

Currently we are using a set of BioPac cables on loan to us from another researcher. I deal with DSP and FPGA design so the analog part of this is not my expertise. I'm looking for a nudge in the right direction so I can learn about what needs to be done. Thank you!


texts: Inverting, single-supply comparator not working as expected

texts:
I am trying to convert an input sine wave to a square wave. The sine wave is centered at 2.5V and has an amplitude of 2V, with a frequency of 100kHz.

I am looking for a hysteresis of 100mV centered around 2.5V. (ie. 50mV below and 50mV above 2.5V)

I am trying to achieve something like the following (except that the output is inverted), where both waves are centered about 2.5V:

To do so I looked through Design with Operational Amplifiers and Analog ICs, and I thought that I could work with a VTC offsetting single-supply inverting Schmitt trigger.

I then calculated the resistance values according to my parameters.

VTH = 2.55V
VTL = 2.45V
VCC = 5V

Assuming R3 = 100kΩ and R4 = 2.2kΩ, I calculated R1 and R2 both being 4.1kΩ`.

I proceeded to construct the circuitry on Proteus software using the LM311 comparator.

And here is my output.

Yellow is Channel A, Blue is Channel B.
I zoomed in on the square wave can be seen from the dials.

The output is not only attenuated, but also unevenly centered. The book mentions none of these effects, so I suspect that I am missing something more fundamental here. Any suggestions on what I am doing wrong would be appreciated.


texts: Best microcontroller for industrial applications

texts:
I have an industrial project requirement to build a device having this functionality:

Store Data
Send Data to Web Server
Device to be placed under scorching sun
Sensors - around 5
A Graphical Dashboard
RFID authentication
Buzzer

And maybe a couple more. I am totally getting confused which microcontroller to use:

MSP430
ATMEL
PIC
ARM (Cortex)
etc

Or others but I am not sure - I presume that there are other families also for my aid which I don't know. So which microcontroller should I use based upon performance, storage, durability, speed, architecture and robustness?


texts:
In the book I am reading, there is an experiment that consists of connecting an automotive style fuse and a 1.5V battery to observe blowing of a fuse.

However my fuse does not blow. I have repeated the experiment with a 9V battery but still it doesn't work. After these results, I have tried the experiment using a DC to AC adapter which can output up to 12V.

When I tried the experiment with 12V, tiny blue sparks would appear at the connection between the fuse and the adapter's output. Furthermore, the fuse had warmed up but it still did not blow.

Why is this the case? I initially thought that the fuse would blow as soon as I connect it to any amount of voltage since there is virtually no resistance. Why my fuse doesn't fuse?


texts: Detect the first rising edge of 3 input signals

texts:
I have 3 input signals which are pulse waveforms The output is switch to high once once  all 3 first rising edges of 3 inputs are detected.
Is there a digital circuit from logic gates, flip flop that can do that?
I am thinking about flip flop but the problem is that it detects with every rising edge not just the first rising edge.


texts: What should I take in account when using a more powerful triac?

texts:
I'm familiar with simple dimmer circuit, now I want to build a more powerful triac unit to use with a high power heater.

The resistance of my heater is made of 9\$\Omega\$ 3mm diameter nichrome wire. On 240V(rms) voltage this makes 25A(rms) current. I have an access to a mains line capable of delivering 30A, so in theory I will be able to drive heater at full load. In reality I probably won't, but nevertheless, I want to build a unit that could do that in theory if needed.

My question is - what should I take into account when building a simple optotriac/triac/zerocrossing circuit when moving from 8A triac to 40A triac?

Triac i'm going to use is this: BTB41

My schematics looks like this:


texts:
This question will probably be downvoted pretty quickly because it sounds like a shopping question, so let me start off by saying I am not looking for the lowest price, or even where to purchase this component. I would simply like to know if a manufacturer exists, and if not, what are my alternatives.

A project I am working on requires a slimline USB3.0 Type A socket with a height not in excess of 5mm. Standard USB sockets are about 5.7mm tall so I am looking to source the plastic insert of the socket and will fabricate the shielding myself as part of the device's enclosure.

(source: digikey.com)

Something similar to this but in a female version (just the blue part with the contacts)

I have searched Mouser, DigiKey, Element14, and Alibaba with no results.

I have considered using the PCB itself to form the contacts as I am aware this has been done successfully for Type A plugs (fig. 2), however for the socket I will need to source the 4 spring contacts used by the original USB standard (VBUS, D-, D+, and GND).

The contacts for StdA_SSRX-, StdA_SSRX+, GND_DRAIN, StdA_SSTX-, and StdA_SSTX+ could simply be pads on the PCB.
USB2.0 Type A PCB Contacts http://www.theledart.com/blog/wp-content/uploads/2012/09/TPP_5890.jpg

I can also use an existing USB3.0 Type A socket and peel away the metal shielding to leave only the plastic insert with the contacts, but if possible I would like to avoid this.


texts: Microcontroller GPIO input voltage limit

texts: I was looking at a datasheet for a microcontroller and noticed that, under its section for GPIO input voltage (p.14), there is no listed maximum for the high input, only a minimum. Does this indicate that, ensuring I keep current below the maximum (which I would assume to be 20mA from the current sink specs), I would be able to put any voltage through the pin?


texts: How do D flip-flops (dff) start up in Quartus?

texts:
If I connect Q0 of one dff to its D0, its Q0 stays 0. But if I take another dff and connect its Q1 with Q0 of the first dff through OR to his D1, its Q1 stays 1.

I understood that all registers are initialized to zero on FPGA power-up. But even if so, when I compile the design and run it on the FPGA, LED0 is off, while LED1 is on!

[EDIT] If k0 is 1 at any point, how come that it doesn't stay 1, given that it is directly connected to D?

What is actually happening here?


texts: How closely do the input buffer op-amps need to be matched on discrete instrumentation amplifiers?

texts:
For discrete three op-amp instrumentation amplifiers, we know it is very important that the resistors be matched.

https://en.wikipedia.org/wiki/Instrumentation_amplifier
However, I have found almost nothing talking about matching of the input opamps. How important is it to match these opamps?
For example, do they need to be on the same die in the same package? Would using op-amps of the same type but in two separate packages destroy the common mode rejection? Or would the closed-loop gains sufficiently work itself out negative feedback reigned in the extremely high open-loop gain, even if the open-loop gains were different to begin with?


texts: Shift register activating transistor doesn't work as expected

texts:
I'm trying to make a led cube by multiplexing by floor. I'm using 74hc595 shift register to extent arduino output and transistor for alimenting led. But while doing some tests, I had some problems with the transistors: When I want to light one led per level (for example the green and the black one), the two others light up slightly too. By adding delay in the arduino code, I can limit this problem or even remove it, but losing the retinal persistence.
To test if the problem was coming from the 74hc595, I did the test by removing the transistors and directly powering the leds from the 74hc595, and I don't have this problem anymore. So I guess the problem comes somehow from the transistors or from my electrical circuit.
Here are the schematic with the transtor that does not work and the one without that work fine

I know I should use a capacitor between VCC and GND for the 74hc595 but I don't have any and it work fine without transistor so I don't think it comes from that. For information, I use the SPI.transfer function to communicate between arduino and 74hc595.
Is it possible that the transistor cannot switch fast enough for this use ? Or it is a bad design ?


texts: Microcontroller with >30KB RAM and high performance in a TQFP-44 or similar package

texts:
I'm looking for a microcontroller in a TQFP-44 package with 30 KB or more of RAM and, if possible 40 MIPS instruction cycle speed or faster. I can find dsPIC33F's with 30 KB of RAM, but they come in TQFP-100 packages, and I'm only going to be using maybe 15-20 pins of those so it seems like a massive waste of space and money.

So I'm looking for some reasonably sized package with lots of RAM. I've given up on the SO28's but if anyone finds one it would be excellent as well.

Current candidates are the Parallax Propeller, but that only has 20 MIPS instruction cycle, and the dsPIC's in TQFP-100's. One parameter but not both!!

This is for my Super OSD project.


texts: How to connect this Relay Module to printer port (LPT1)?

texts:
Hello,
have this relay board, how can i connect this board to a printer port (LPT1) and can this port cope with the amps needed to drive the board?
I am not an electrician, so please take notice of this fact in your answer.
This relay is needed to switch a router motor on and off, the signal is send from "Mach3" (Milling software) through the printer port (LPT1).
The motor is 1050w 5a 230v AC.


texts: Is electronics driven by scientific papers?

texts:
Is electronics driven by scientific publication, similar to other academic fields? Two famous publications I came across, Gordon Moore's seminal paper, and Leon Chua's discussion of the memristor, did not leave me breathless.

Coming from a mathematics background, I have been disappointed by electronics theory. No visionaries stand out, especially contemporary ones.

Is electronics simply not a publication-driven discipline? Are there examples of seminal papers where theory paved the way to technological breakthrought?


texts:
One of my hardware modules uses a state machine which is triggered when the input signal IN is HI (that's an LVDS pair on Microsemi proASIC FPGA). The problem arises when nothing is connected to the LVDS input pair - so my state machine triggers spontaneously, as expected. I wanted to "Pull down" the input and tried to set the constraints for IN_P and IN_N pads with -res_pull down and -res_pull up respectively in the constraints file as suggested here. This gave me errors saying that those are unknown pin attributes. And indeed, when I opened the interactive compile interface, there was no option to select up/down pin pulling for the LVDS standard.

But then, how to set my LVDS input to a known (low) state when it is not connected? Is this limitation Microsemi specific, device specific, or there is no such thing as pulling LVDS pairs internally?


texts: Arduino reboot with DIY H-bridge Controller

texts:
Here is my already tested and working schematic of the DIR +PWM mode DIY H-bridge on DPDT relay with IRLB-3034 N-channel MOSFET with opto isolation from the controller, and some "quick gate" driver for the mosfet. What can be the reason of the controller reboot? From time to time. What can be done?
The motor is working in the application with almost constant stall condition.

May I consult, wheather a relay snubber has the right connection?


texts: Voltage Controlled Current Source integrated circuit? Exists?

texts:
Does anyone know of a Voltage Controlled Current Source IC? Or do you know how I can build one with as few other components as possible taking up a minimal amount of space?

current range needed is from 0mA to 350mA


texts:
I'm currently trying to build a soldering station. Everybody on the internet uses AC-voltage for that, but I haven't really found the reason for that. So I thought "Well, let's build one and see if it works with DC as well".
At first I wanted to switch the heater element with a single MOSFET, but unfortunately the thermoelement shares a common ground with the heater element. That's why I thought about this design, which is quite similar to an H-bridge. As far as I understand it should do a good job of isolating the SS_GND- and SS_Heater-Pins when I turn Q1 and Q2 off, right?
I'm not too experienced with this type of electronics, so I thought it's better if I ask someone else first.
Thanks for your help!


texts: Need help getting 190Vpp to signal readable by AD/DA

texts:
I created a system that records the rate of oil being pumped through a turbine using a Honeywell 3030AN VRS Magnetic Speed Sensor. The 3030AN output voltage is 190 Vpp and I have an 8AI-SPI AD/DA connected to a Raspberry Pi 3 which reads the change in voltage.

I'm looking for a Frequency-to-Voltage converter that will convert the 190 Vpp (15 kHz operating frequency) to a voltage readable by the 8AI-SPI.

I tried contacting Honeywell to see what they recommend for their VRS sensors, but have yet to get a reply. Any feedback will be greatly appreciated!


texts: RF Cable testing-- Ripples during S21 measurement

texts:
During the testing of RF cables, I am seeing ripples during S21 measurement. It is almost straight till 2.5GHz, but between 2.5GHz and 3GHz unit is showing ripples .

May I know the reason for this phenomenon?


texts: At what clock frequency do parasitics start to become a problem for digital circuits?

texts:
From what I've read, designing low speed digital circuits is trivial, but designing high speed digital circuits is intractibly difficult.

Every single piece of conductive material has nonzero resistence, inductance and capacitance. At low frequencies, these numbers are utterly insignificant, and you can just pretend that logic gates work how their truth tables say. At high enough frequencies, these numbers stop being insignificant, and suddenly everything becomes drastically more complicated.

Really, my question is... at what point does this happen?

(Obviously this can only be answered approximately.)

In particular, I hear a lot of people complaining about how "terrible" breadboards are and how they have "huge amounts of stray inductance and capacitance". So if I'm wiring up discrete logic gates on a breadboard, how fast can I realistically expect them to operate reliably? Is double-digit Hz a realistic goal? Or am I limited to something under 2 Hz or so?

(Somebody pointed out that the datasheet for the gates I'm using states a "typical" switching time of 8 ns. If you naively compute \$ \frac{1}{8 ns}\$, it comes out as 125 MHz. Obviously that's the maximum theoretical frequency for the most trivial circuit possible. Even so, it is completely implausible to me that anything I could assemble with my bare hands would ever go anywhere near that fast. There's a reason high-performance computers cost tens of thousands of dollars...)

Note, I'm not asking "how fast can I clock this thing?" That's a much more complex question. I'm asking "what's the maximum switching frequency that can be in the circuit before analogue weirdness starts interferring?" And, again, I'm asking for an ball-park, not hard numbers.


texts: I am using a magnetic contact sensor to detect whether the door is open or closed. The sensor will be connected to WISE-4060 module . But the question is that I will be using 300m long cable. Is is possible to use that sensor with long cable? Is that affect the sensor value significantly? What kind of cable should I choose?


texts: Help To Identify Electrical Connector (possibly JST)

texts:
Does anyone know what type of connector this is with the 11 wires in it please? I'm after the male version.

I thought JST GH but it looks like probably not...

EDIT: I only have the female receptor. Here it is...


texts: Instanciating blocks in VHDL, asignment of clock and reset signals

texts:
I am trying to connect 5 stacks together using VHDL below. The main problem I am facing is that that I don't know how to deal with the signals clk which stands for clock and rst which is asynchronous reset and the SOp stack operation signal-vector which used in its entirety by each of the stack instances. TS stands for top of stack.

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity stack is
    port(
        D : in std_logic_vector(4 downto 0);
        TS : out std_logic_vector(4 downto 0);
        clk, rst : in std_logic;
        SOp : in std_logic_vector(1 downto 0)
    );
end entity;

architecture structural of stack is

begin
stack1: entity stack port map(
      D  => D(0),
      TS => Tos(0),
      SOp => -- here
);

stack2: entity stack port map(
      D  => D(1),
      TS => TS(1),
      SOp => -- here
);

stack3: entity stack port map(
      D  => D(2),
      TS => TS(2),
      SOp => -- here
);

stack4: entity stack port map(
      D  => D(3),
      TS => TS(3),
      SOp => -- here
);

stack5: entity stack port map(
      D  => D(4),
      TS => TS(4),
      SOp => -- here
);

end architecture;

Should I basically type something like this or can I just skip SOp, clk, rst as they are used completely by each stack?

stack1: entity stack port map(
      D  => D(0),
      TS => TS(0),
      SOp => SOp,
      clk => clk,
      rst => rst
);


texts:
I'm using an opto triac, specifically the MOC3041, with a zero crossing circuit to switch the  Tx pinout on an RS-232 interface.

I have no problems turning it on, but after I unload the input (no input current), the triac doesn't turn off.  The load is standard RS-232 voltages (+/- 12V), speed 56k.

Do I need a snubber on the load?  If so, how should I calculate the value of the snubber it?

EDIT

I've already asked a question here on the site and I didn't get the answer.

Here is the original one:

"I have a modem connected to a server through RS232. The server is constantly sending data to the modem, whether the modem is connected or not.

When I try to connect to the modem with another modem the handshaking fails because the server is sending data that gets in the way.

I am looking for a way of stopping the communication between the server and the modem until the modem's DCD line is asserted.

What kind of device or component could be used to design a small passive (no power supply) circuit that could perform this operation?

As far as I can tell it is only the TX line that needs to be interrupted while the modem is off-line."

Schematic

Hope it is more understandable.
Thanks.


texts:
I am trying to solve section d in the following question by substituting a current source of -Ios/2 at the '+' and +Ios/2 at the '-', as the resistor(s) found in section c would nullify the output for all the other offsets, namely IB and Vos. However, I obtain a result which is different than that asserted in the formal solution and wished to confirm my method here.

For a 150K resistor connected to '+' and IB flowing away from the ground the output would be zero. Except that now Ios is added. Hence, using superposition:

For the -Ios/2 source connected to '+' and flowing away from ground: (Ios/2)*150K=Vo

For the +Ios/2 source connected to '-' and flowing away from ground:

Vo/100K=(Ios/2)

This yielded 1.25mV, whereas the official answer is -1mV.

Where's my mistake?


texts: Suddenly I am baffled, as a hobbyist I made a variable constant current power supply based on LM338. But I never thought what could happen if I accidentally turn it on without load, will the voltage keep rising? I cannot see how, let's say the input voltage of LM338 is 30V, then the output can never rise above 30V in case there is no load, right? Or is going to be some spectacular failure of the device?


texts:
simulate this circuit – Schematic created using CircuitLab

I currently have a circuit with a 2N3904 BJT that acts as an on/off switch. I want to add a second BJT in parallel that toggles an LED on/off to indicate the on/off status of the first BJT.

I've tried simply connecting the bases of the two transistors together, but this has not worked, I think due to insufficient base current now that the current i is being split between 2 transistors.

If I halve the biasing resistor values to double the amount of current, but maintain the R1/R2 ratio, should this theoretically work?

Thanks

Edit: Apologies for not adding a schematic, I wasn't aware there was a built in feature. This is the schematic I tried, which obviously did not work. Upon reading the comments, it seems that adding a resistor in series with the base of each transistor could help solve the biasing issue?


texts: Brushless DC motor - number of hall sensors

texts:
When we have hall sensors inside a BLDC to use as encoders for the processor, I saw some diagrams on web showing 3 output signals (open collector outputs, need external pull-ups to the VCC of processor).
It is ok to use only 2 sensors and be able to control the motor properly? I have a situation where a have only 2 inputs... 2 signals of encoder is enough?


texts: i want to use the TIP122 darlington transistor with my atmega8 to control a 3A 12V geared DC motor. i found that the current gain is 1000 for tip122 from its datasheet. so the base current for 3A output is 3mA(am i wrong?). So i used a 1.6k resistor to limit the current from atmega8. I breadboarded the circuit and found that i get only 4v emitter voltage even though i the supply voltage is 12.4V. why is this so? i removed the resistor and again i get the same voltage( base current from atmega8 without resistor is 40mA). i simulated the circuit in Proteus and still the same result. So something is wrong? Please help me with this.


texts:
I'm using Atmega8 with HC-05 bluetooth module for communication with android bluetooth.
The connection was success. But i want microcontroller to detect whether the HC-05 is connected with android or not ?? Is it possible? if yes please provide the solution.


texts: What is the response curve of a CMOS sensor cell to the amount of light?

texts:
Using my Nikon D5100, shooting RAW pictures and using Darktable to disable absolutely all contrast curves, white balancing, sharpening and even the debayering, I've measured the average value of the green pixels of each picutre in a test (by green pixels I mean the actual physical pixels behind the green filters of the bayer filter, the other pixels where ignored).

This test consisted of, using a constant light (in both intensity and spectrum) and varying the exposure time, find the variation of the average value of the green pixels in respect to the total amount of light in each exposure (as everything else was kept constant, the amount of light integrated in each exposure was directly proportional to the exposure time).

I've got the true exposure times from this site, which I checked to be exact in the millisecond range with a microphone recording the shutter sound.

Then, I made a graph of the normalized exposure times VS the normalized average green pixel values for those exposure times.

What I expected was to see a 45º straight line, with the values being directly proportional to the amount of light integrated in each exposure.

But instead I got a way different graph:

This here is quite obviously some particular response function of the CMOS sensor. I didn't find which function makes the best fit on this data yet, logs didn't work very well.

So, what is this response function and why is it like that?

Thanks!


texts: Using back emf for charging window-blind controller battery

texts:
Let me start: I have no clue of electric engineering. However, I built an automated window blind controlled by my home automation.
It consists of a stepper motor, motor controller board, an ESP8266 and an Ikea battery pack (7.2V) which they use for their window blinds. So far so good, I can control those by software and by a switch. Every now and then I have to remove the battery and recharge it.
Sometimes these blinds move quiet slow and I lower them by hand. The motor shield protects the ESP circuit against the current produced by the motor. However, I wonder if it would be possible to adapt the circuit to charge the batteries instead.
As I said, I have no clue of electric engineering. Is this even possible? In my eyes this would be awesome to not "waste" the energy produced by manually lowering the window blinds. (A dream would be to balance the energy needed to raise the blind with the energy produced by lowering the blind by hand, but that's just a dream)
BTW: found this blog here Understanding regeneration
Hope I find a creative, helping spirit here :)


texts:
Does anyone know of any impedance matching techniques to match at two different frequencies? Where the impedance at both desired frequencies are different (both the real and imaginary components)?

Most of the papers regarding dual impedance matching assume that the impedance is constant across all frequencies.


texts: interfacing a Stratologger altimeter with an Arduino Uno

texts:
The Issue
I am trying to interface a stratologger altimeter to my arduino uno and I'm unable to successfully read data being output by the altimeter.
The Setup
I have a stratologger altimeter, an arduino uno and a 4 bit bi-directional logic level converter to connect the two.  Here are some reference pictures for what I have failing so far.

Picture 1: the whole logic level converter and arduino in 1 picture

Picture 2: up close on the logic level converter

Picture 3: up close on the arduino

Picture 4: the connection to the stratologger
Quick wire reference:

yellow: from the high voltage bit B1 of the logic level converter to the rx pin 0 on the arduino
blue: from the tx pin on the stratologger to the low voltage bit A1 on the logic level converter
green: 3.3v on the arduino to the low voltage reference pin on the logic level converter
red: 5v on the arduino to the high voltage reference pin on the logic level converter
black: ground.  there are 2 separate connection from arduino to high voltage ground on logic level converter and from the ground on the stratologger to the log voltage ground on the logic level converter

The code I'm using to test this is:
const int ledPin = 13;

void setup() {
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);
  Serial.begin(9600);
}

void loop() {
  if (Serial.available() > 0)
  {
    digitalWrite(ledPin, HIGH);
  }
}

That's the simplest thing I could think of to notify me if the arduino is receiving data.  When I have the arduino connected to the computer, this code works great by just typing something into the serial monitor.  I disconnect the computer for the actual tests since this will be used without a computer during the intended usage.
The altimeter comes with a serial connector for the computer and I ensure that the computer reads the telemetry output that the altimeter is sending data before and after trying to interface it with the arduino.  Stratologger manual, page 44 contains the relevant data for the telemetry output.
What have I tried?

I have connected a volt meter to every part of this to try to see if I can detect data actually being sent but I can't really tell
The arduino idles high on the rx pin as does the stratologger, but I don't know if that's a problem or not
I have tried every bit connection on the logic level converter
I have written code to verify that serial port is actually opening up on the arduino
I have tried manually setting pin 0 to input

I am out of ideas
I feel like the most likely issue is that I set up the logic level converter incorrectly because I'm pretty green when it comes to electronics.  I used this guide to help me get the wires I have them.  This is the actual logic level converter that I am using.  Is that the right thing I need to be using at all?
I'm pretty confident that the code is good and that the serial port settings match what's listed in the stratologger manual linked above, but maybe I'm wrong there also.  If that were the case I would expect jumbled data coming through, not just nothing.
I'm most confident that I have the stratologger set up correctly because it comes with the tools to set it up automatically and I verified it is sending data to the serial port by reading the data on my computer.
I feel like I am missing something simple and it will just start working after that, and I certainly hope that's the case.  Does anyone have any ideas?


texts: How can a car battery be charged by dynamo (or is it an alternator?) at the same time it is being used by the car components?

texts:
note and question

* Is it an alternator or dynamo?

I am not an electrical engineer and neither have any core knowledge but, this is a simple procedure of car battery charging using a dynamo, which is present in all cars and bicycles. But what i don't understand is how can a battery be utilised and charged at the same time?

* That is, head lights drawing current.
* But dynamo is giving current.
* Everything done by using same battery terminals.
* So BHOOM must be a explosion!!


texts:
I’m taking a subject of entrepreneurship and we have to present an idea to put in the market. My group thought about a keychain with a little light that warns us if we locked our front door or forgot. In case we don't lock, the light of the keychain is red. Otherwise the light will be green. We don’t have a deep understanding of electronics, but from what I searched I think the best way to do this would be with a piezoelectric sensor installed in the lock, so that when the door latch goes into the cavity, the sensor will be activated. I probably also need a arduino, right? To receive the information of the sensor. My question is: what else do I need to send that information to the keychain? How can that be done?

What are the main components to do something like this?

If anyone could explain me just the basics, it would be a big help already. Thanks.


texts: Can you and/or why should you not replace optocouplers with transistors when dealing with slightly different voltage

texts:
I stumbled upon this:

Source.

The MDB bus is communicating at a 34V level and the other side is at 5 or 3.3V.

Why are they coupled with optocouplers rather than a voltage divider on the master tx and a normal transistor on master rx?

What are some potential problems with such a design?

I am a layman at electronics so low level explanations would be great.


texts: How to design blinking LEDs circuit using analog elements only?

texts:
I want to design a circuit to blinking three LED in a row with 2 second delay for shifting/changing using analog elements only (using Resistors, Capacitors and Transistors and without Micro Controllers).

To be more clear, let assume I have three LED on my board that named LED1, LED2 and LED3.

This is the procedure:

LED1 turns on at the power up and the two others are off now.
After 2 seconds, LED1 turns off and LED2 turns on.
After 2 seconds, LED2 turns off and LED3 turns on.
After two second go to step 1 and repeat again.

How can I design it?

Thanks in advance.


texts: Having trouble with determining why my XNOR transistor circuit is not behaving

texts:
this is my first post. I've been working on creating logic gates from 2N2222 transistors. I've build a basic switch, NOT Gate, OR, NOR, AND, NAND, and XOR (from a combination of the others). However, when I extend this to the XNOR, I get weird results.

I started by building the circuit from NAND, OR, and AND, following this: http://hyperphysics.phy-astr.gsu.edu/hbase/Electronic/xor.html#c1. I then just wanted to add a NOT on the XOR output. I figured this was the best way to build up my knowledge from smaller parts.

When I run this with 3.3V, the circuit (blue or red LED lights up) follows the XNOR truth table. However, when I switch to 5V, I get weird behaviour:

when both inputs are OFF, the LED is on, but not too bright (call this bright)
when I turn one input ON, the LED dims; to be less than what I see in (1) (call this less bright)
when I turn on the other input, it is the same as (2) (call this less bright)
when I turn on both outputs, the LED is the brightest (call this brightest)

One of the first things I tried to debug this was connecting the output to a simple transistor switch that powers an LED. This works just fine. When XOR is ON, the transistor switch is on, and LED is on. When the XOR output is OFF, the LED is off. I then changed from the simple transistor switch to the inverter (NOT) gate and that's when I had issues.

I chose 10K for each base resistor, and 1K for the resistor either at Vcc or at Gnd. I chose 470ohms for the LED output (the LED is 3.0V to 3.2V and needs 20mA). I've tried changing the resistors at Vcc and Gnd to 4.7K to closely match the 5K that the link above showed. Again, this doesn't fix the issue.

I have attached a picture to show the circuit. It isn't too clean, but I hope it helps. This shows the 3.3v setting, and this is when the circuit behaves as I would expect.

Edit: I hand drew the schematic. I’ll look into a schematic tool or the embedded editor next.


texts: Using op-amps to read real-time resistance values over a wide range

texts:
Background

I have been using a simple inverting op-amp circuit and Arduino to measure the resistance of a photoresistor (light 5k, dark 200M), like in the schematic below. This provides linear data which is good for the calibration of light intensity.

simulate this circuit – Schematic created using CircuitLab

I used -5V as the input voltage. The output voltage was reading from an Ardunio Uno (resolution 10 bits). The resistance of the photoresistor can be calculated as below.

R = - RF * Vin / Vout

The measurable resistance range is decided by the resistance RF of the reference resistor. Taking the RF = 1k in the schematic and Vin = -5V as an example, the measurable resistance of the photoresistor is from 1k (Vout = 5V) to 1.023M (Vout = 1/1023 * 5V), despite of the decreased accuracy in the large resistance range.

Question

Now I need to measure the real-time resistance change of the photoresistor over a larger resistance range (1k to 100M).

Is there a way to improve this circuit, to be able to measure the dynamic resistance values of the photoresistor over at least five magnitudes (1k to 100M)?

I read this post "Reading dynamic resistance values over a wide range"
but I still want to keep with the inverting op-amp for its linear output, which makes it easier to calibrate the light intensity for my test.

In the meantime, I also try to divide it to several ranges. I am using extra analog input ports on Arduino to read from extra inverting op-amps with shared photoresistor but different RF, i.e., op-amps in parallel. As shown in the schematic below, I planned to use a current mirror to provide the same input for these op-amps, and use different reference resistors in these op-amps. By carefully selecting these reference resistors, it should be possible to have at least one output with good resolution. However, this design may produce very high voltage to damage the Arduino...

simulate this circuit

Follow up on July 29, 2019

Thanks to @GRTech 's suggestion of using a log amplifier, I simply put the photoresistor in a log amplifier as shown in the schematic below.

simulate this circuit

According to the calculation:

Vout = n * VT * ln(Vin / (R * Is))

The measurable resistance range would be largely increased as shown in the picture below. I think I just need to figure out a way to make the output voltage to span from 0 to 5V to maximize the resolution on Arduino analog input.


texts: Why is the closed gain loop -3dB from the open loop gain rather than some other value?

texts:
I am reading the book Op Amps for Everyone and in the chapter of feedback loop theory, I have this quote (see picture) where it says in reality the closed loop gain is down by 3dB at the point X as shown below.
How does he know it is -3dB and not some other value that is proportional to the gain B?

page number 85, link to the book:Op Amps for Everyone


texts: Volume of sand in a cat box - ultrasonic sensor?

texts:
My cat is always making fun of the sand that is inside of his sanitation zone :)

In order to better control the amount of sand that is present on the container I'm developing a communications circuit to collect data from the box. But I would like to develop something that could give me volume of the sand that is in the box. The idea is to collect values 4 times per day. Is it possible to achieve this with an ultrasonic sensor ? I have no experience with this kind of sensors. Any ideas or tips ?

I was also thinking in taking photos and having a service to analyse the photo. But this option is more time demanding and needs light adjustments...

The box has 100cm depth x 100cm width x 70cm height (I can expand if necessary, which will be for the sensor)

Can I make it with ultrasonic sensor ?

Thanks!

Best.


texts:
I was wondering if it is possible to communicate between 2 BLE devices when one is placed inside the car and another placed outside the car. Can BLE communicate in such a scenario?

For example, I have a sensor system (collision avoidance system) placed on the grill area of the car, It is connected with BLE to transmit the sensor data. There is another BLE placed inside the car which is receiving the data from the sensor, so when driving the car (consider all the windows are closed) can I receive those data from the collision avoidance sensor inside the car?


texts: How to display characters on LCD with FreeRTOS

texts:
I ported FreeRTOS on EFM32 based kit by EnergyMicro. After porting I want to develop a simple application that will display Hello World on the LCD.

When we talk about windows OS, we have a function printf() that interacts with OS to stream out the Hello World on the LCD.  What do I use in case of FreeRTOS to put Characters on the LCD?

The closest match that I have found is FreeRTOS_write().

FreeRTOS_IO.h

size_t FreeRTOS_write( Peripheral_Descriptor_t const pxPeripheral,
                       const void *pvBuffer,
                       const size_t xBytes );

Writes one or more bytes to an open peripheral.

The board support package defines the peripherals that are available to be opened. FreeRTOS_ioctl() is used to select between interrupt driven and polled write modes.

Parameters:
pxPeripheral    The descriptor associated with the peripheral to which bytes are being written. The descriptor will have been returned from the FreeRTOS_open() call used to open the peripheral.
pvBuffer    A pointer to the first byte of data to write.
xBytes      The total number of bytes to write.

When an interrupt driven transfer mode is being used, the actual number of bytes written to a peripheral may be less than the requested number if not all the bytes could be written before the peripheral's write timeout expired. FreeRTOS_ioctl() is used to set the write timeout value.

Can somebody explain me how to use this function for display?
I am not even sure whether this will help me or not. Please enlighten me if this is not the correct approach.


texts: Inverting amplifier saturation with capacitor

texts: R1 represents a resistive sensor in the figure below. In reality, it has also a capacitor in parallel. I'm trying to understand the effect of this capacitor. When a parallel C(is labelled as C2) is added, the output is saturated. What is the explanation of this? How can i tackle this C which negatively affect the output?


texts: Maximum capacitive loading for DC-DC converter - how to calculate?

texts:
Following this answer I looked into the datasheet of the OKI-78SR-5/1.5-W36-C and see the following:

In general the requirement is clear for me: resistance at the start event must not be too low for regulator to go to shortage protection state and fail starting.

I am not sure how to calculate the ESR for the circuit which is going to be powered by the regulator. The circuit is having one 10TPB220ML, three 10TPB47M, and quite a set of GRM21BR61C106KE15L and CC0805KRX7R9BB104.

Bigger caps have ESR listed at 100 kHz (page 2), and direct computation gives 0.016 Ohms. Then looking at the GRM21BR61C106KE15L ESR graph (page 2) I see that its ESR at 500 kHz (operating frequency of the converter) is well below 0.01 Ohms.

Thus logically one GRM21 cap at the output is enough to trigger max 300 uF condition per datasheet.

This sounds really strange for me as I think I assume and calculate something wrong. Regulator's datasheet does not list conditions ESR to be measured in, so I am stuck.

The only reasonable thought I have regarding MLCC is that when device starts, its "frequency" is zero, thus 10 Ohms ESR applies, and thus I need 1000 caps to trigger 330 uF condition for regulator, and ESR does not matter for regulator when it starts and gets up to its nominal output voltage level (as ESR is applicable to the high frequency noise component, and not to the full swing voltage).

What do I miss here?


texts: Confusion in deriving ripple voltage for an unregulated power supply

texts:
Above is a full wave rectifier as an unregulated power supply

(please left-click with your mouse to enlarge the image)

In many texts and tutorials the ripple voltage(|AX| in above figure) which is

deltaV = I / (2*f*C)

I think it comes from the fact that

C * dV/dt = I so deltaV = (I/C) * delta_t;

and according to texts since delta_t is T/2 = 1/2*f

then deltaV = I/(2 * f* C) where I is the load current.

I can understand that derivation but if you look at my image above, according to this equation the real delta_t is not T/2 but instead less than that. Hence the ripple is |AX| not |YC|. But the tutorials take delta_t as T/2 where it starts from the point A to point C. But actually delta_t starts at point A and ends at point B.

Im confused at this point. What is the real ripple Voltage here?


texts:
I have an alarm device. It convert 12v to 4,3V to the phone. It's outputs are 4.7V, GND, and two output to the phone buttons

If the inputs loop of the alarm device is opened that means the wire have been cut, so it gives a signal to the buttons, so the mobile is start dialing a given phone number. Now because the something went wrong with the previously phone. It was needed to replace the phone so I am trying to interface a motorola t191 to the alarm curcuit. If I give 4.3V direct to the phone it doesnt accept and show an "invalid battery" message. The battery has 4 pin. I measured the battery curcuit to figure it out how to attach my supply.

The pins of battery are:

pin1 B- Battery negative
pin2 BATID Battery ID
pin3 TBAT TemperatureBat(thermistor)
pin4 B+ Battery positive

I found the the schematics of the battery. http://monitor.net.ru/forum/files/motorola_t191_-_dorabotka_v_cepi_raz_ema_akkumulyatora_546.png
I took apart the battery I have. http://imgur.com/W73Y7K5
R1 is the battery id resistor
R2 is the thermistor
It is different then the curcuit above.

Is there a way to power this phone with my 4.3V external power, or a simple way to solve this?  Any help is appreciated.


texts: What does it mean 'package limitation current' on a MOSFET datasheet?

texts:
I was looking at the datasheet for IRF1405 and got really excited when I saw 169A @ 25C!
Then I started scrolling down and it says 'package limitation current is 75A'.
Does that mean the maximum current I can get out of this MOSFET is 75A? And what does it mean when it says 'package limitation'?
Are they talking about the maximum temperature that the package can handle before it melts which is why it can only take 75A?


texts: Getting UART Overrun Error with HAL_UART_Transmit() vs HAL_UART_Transmit_IT()

texts:
On my main board I have a STM32F103ZET6 and I use HAL library V1.6 in order to program it.There is also a sensor board which is connected to my main board and this sensor sends me data through UART continuously. In order to get sensor data, I use RXNE interrupt.
There are some commands that I can send to this sensor in order to change some setting of this sensor. when I want to command this sensor and send some data to it, If I use HAL_UART_Transmit() (send data without using TXE interrupt) I get overrun error in some times. But when I use HAL_UART_Transmit_IT() (send data by using TXE interrupt)  it seems that I get no error. why does it happen?

In reference manual RM0008, on page 794 we have USART block diagram.
Although it shows that we have separated RDR and TDR but it seems that we have only one DATA Register that is shared by TDR and RDR and we have direct access to only DR. when we want to transmit data we should write in DR and and when some data received it is put in DR too. Now consider , meanwhile we are sending data and put some data in DR, there is a data which is being received and triggered interrupt. what would happen? Does this cause an Over run Error?


texts: Implementing Control Commands for an MCU over Serial

texts:
Im looking to integrate a command interface in a project that im making that will accept commands overs serial from a PC.

The idea is that the device will do its thing but it gets sent a command, it will perform it.
This is different to most examples i've managed to find which is just an idling device waiting for serial data.

So for example, a device which controls LEDs and plays an animation.
Lets say theres 3 preset animations, and when it turns on it always plays number 1.
On the PC side I would send a command 'play preset 2', or 'change color to green' or sending a live real time animation to the device to play on the LEDs.

So my question is that I can not find much information on this "design pattern" ? I do not know where to start to look.
The closest i've come is pre-made arduino serial parsing libraries. However im looking for more of C / non arduino / theoretical approach.

I have looking into serial protocols but that is just things such as SPI and I2C etc, not actually how to implement a control / command interface in software.

I also found out about HDLC, again though it seems to be more of a standard / a protocol. A similar thread is
https://stackoverflow.com/questions/1445387/how-do-you-design-a-serial-command-protocol-for-an-embedded-system
Which has some very nice information but again its to do with the protocol / communication itself.

Im trying to find how to code / implement this to create a command or control ability.

Do I use an infinite loop to monitor and catch the serial for an incoming command, and use a list of IF statements to choice what command to carry out, but then what happens when no commands and the system should be as normal, or if it misses a command?

Interrupt driven, state machine?

Is there an official name for this that can be used to research and find examples?

EDIT:

For anyone who has the same question, I found this really nice example while researching,
http://www.adnbr.co.uk/articles/parsing-simple-usart-commands


texts: SERIAL/USB game controller reverse engineer

texts:
I recently acquired a Logitech Wingman Formula Force from a thrift store. This controller is marketed as USB or serial port.

By default the controller ships with a native serial connector, but then could be converted to USB using what appeared to be a converter. I am missing that converter.

Due to the fact it claims to have native USB I decided to open it up. Inside I found it has a ADM232AARW Serial Controller as well as a Intel N80930AD4 USB Controller.

The presence of both chips has lead me to the possibility that the supplied converter was not a serial bus to USB converter but instead just converted the connector to work as a USB.

What would be the best way to test to see if my suspicions are correct and how would I be able to figure out the correct pin-outs used to make the conversion?

EDIT:

Here is the board.

Based on a comment below I used a multimeter to track back the pinouts from the smaller connector to the bigger connector. Additionally I tried to get back to the USB controller but was only able to find trace back the connector to D p0, D m0, and V ccp.

With these three connections is it possible to create a crossover cable to USB?

Is it also possible to safely test without risking damage to either connecting device?


texts: ACK even for the not existing register, I2C problem!

texts: I'm implementing this project with MPR121 keyboard communicating with 8051 via I2C before I get further into the program I wanted to know whether the sensor is communicating with the board, giving the wrong addresses to see whether ACK or NACK will be set, when I give the wrong slave address NACK is set and when I give the right one ACK is set so I know sensor is working, but this doesn't seem to work with registers even if I send a wrong register address ACK is set, is this common or what is going on here?


texts: Simple circuit to boost line-level audio

texts:
I am looking for suggestions or pointers to a simple circuit that boosts line-level audio, so that it is strong enough to use with the ADC peripheral on my MCU.

I am aware and have seen many that use an op amp, but I am looking for something cheaper (but still simple), that does not introduce any other artefacts except amplitude boost.

I believe line-level audio is centered at ground and has about a 1.6v swing, where as my ADC input requires a swing of 3.3v

EDIT: My preference is to get this done with a few resistors and capacitors, if that is possible??


texts: stable/unstable equilibrium point in inverter with feedback circuit

texts:
I am reading about ring oscillator here (from page 4) and was stuck at the concept of stable/unstable equilibrium point.

How to know if an equilibrium point is stable or not? For example, the middle point in one inverter circuit is stable while it is unstable in two and three inverter circuits.
 Can anyone explain why they are stable or unstable equilibrium point?


texts: How does the source voltage change with and without channel modulation?

texts:
The description here seems big, but it's only a two minute read. I'm stranded, desperately need help.

The variable resistance R in the figure is set to 10K ohms. The first question was to find the voltage Vs (Source voltage). It is a short channel device with Vdsat=0.6V(Minimum drain voltage for saturation). Threshold voltage Vt=0.4V. Assume zero body-effect and zero channel length modulation.

How I solved it:

Vd = Vdd - IR => Vd = 2V

Now, Vds = Vd - Vs = 2-Vs, Vgs= 2-Vs

As, gate and drain voltages are equal, the device should be in saturation, with or without velocity saturation. (That's what I think, because with velocity saturation the device saturates with Vds< Vgs. Hence, it easily qualifies this condition.)
Now, I calculated Vs using the Id (drain current for saturation) formula. I ended up with Vs = 1.3V, which according to the key is right.

MY QUESTION:
The follow-up question was if Vs would increase or decrease if channel length modulation was considered finite or not equal to zero? It asks for a qualitative explanation.

How I solved it:

For saturation to occur, Vds >= Vgs - Vt.

Here, Vgs-Vt = 2-Vs-0.4 = 1.6-Vs

Vds= 2-Vs

So, for any value of Vs, Vds >= Vgs -Vt. A more important point is the Vds, here, is higher than the voltage required for saturation, which points to the fact that the current should increase linearly with increase in Vds (once saturation is attained, an increase in Vds increases drain current, as we are considering channel length modulation; else the current would've been constant.)

The final step: Taking ohms law:
Considering Rsat as the finite resistance,
Vds = I* Rsat (Inspired from the I-V characteristics curve)

Rsat = (Vd - Vs)/I

Here, as mentioned, we observe that Vd has increased more than the minimum saturation voltage, hence if Vs was constant, 'I' should increase too, to keep the value Rsat constant. But, since 'I' is constant here, due to the constant current source, Vs should increase to maintain the ratio constant. This is my way of deriving it.

Is my solution right? If not, please enlighten and if it is right, please provide your approach to the question, to create a deeper insight of the scenario, both qualitatively and quantitatively(if possible).


texts: Is isolation between user accessible circuits and protective earth necessary for safety?

texts:
First let me say that I understand that this question is best answered by someone familiar with relevant standards (whatever those may be).

Let me give some background. When I'm designing a board at work I usually separate my circuits into several classes. Two of those classes are "signals" and "AC". Nets in the signals class are, e.g., 3.3 or 5 VDC level and may be present on things like user interfaces (the end user doesn't come into direct contact with these nets, but will come closer than to nets in any other class). The AC class contains line voltage nets like 120 or 240 VAC.

For safety we set design rules that say there must be, e.g., 0.250" between nets in the signals class and nets in the AC class. Let's pretend that this clearance is called for by some standard that we would like our products to meet (I don't know if that is true). The nets in the signals class are isolated from nets in AC class by some kind of transformer that can withstand a few kV.

Usually I include the protective earth net in the class AC. This means that signals nets can't come within 0.250" of board mounting points that will be connected to PE.

Now my question. Is this kind of isolation clearance usually required between protective earth and these low level nets? Protective earth is, by definition, accessible to the end user and is considered safe so I see no reason that I would require this large physical isolation distance.


texts: Can I use this IR Transceiver for communication and obstacle avoidance?

texts:
I am building two robots. For communication and obstacle avoidance I am using Infrared. I bought this IR transceiver TFDU4101-TR3 (http://www.farnell.com/datasheets/1675739.pdf)which I thought I could use both for communication and sensing obstacle. I took for granted that it could do both. I now looked 'closely' at the datasheet and saw that it is a module that interfaces to microcontroller serially.

I believe I cannot use this for obstacle avoidance. Can someone please cross check if this can/cannot be used for sensing obstacles and perhaps suggest something.

Also found this on a datasheet of a part very similar to the part above. It says under notes that TX signal echos on RX. If this is the case how can TFDU4101-TR3 be used as proximity sensor?

Thanks


texts:
I am working on an electrical project and I need some advice on resistors and batteries. I have little electrical engineering education, I learned a little bit about circuits in high school a few years ago. The LED lights I’m going to be using are 3.0-3.2V, 20mA current, and 0.06 wattage. My plan is to use 8 AA batteries to power 88 of these LED lights. I am wondering what resistor I am going to need. If you have any better suggestions for the circuit I am all ears. Also, how would I make it so the lights blink. I’m pretty sure I need a transistor and a capacitor but I’m not entirely sure how to get it all working.

Edit: So I decided to switch to C batteries as they have a much higher mAh (8,000) so I think battery life will be fine now. I found a holder that can support 4 batteries so the new voltage will be 6V. What resistor/other components do I need?

Edit: So would I need to put every LED on it's own resistor with a parallel circuit or even every 2 LEDs?


texts:
I have already asked a question regarding this problem but it was about a different thing, slightly. Here is the drawing of a LED driving circuit.

The problem I have encountered with traditional resistor circuit is that I need a very precise current to run through that LED so it produces the desired amount of light.
Lets say 8 bit precision (255 steps). Since LED's Vd can vary with a current I thought that a simple resistor circuit woukdn't be able to give the precision in the desired range, just because there is no way to mathematically express the voltage drop of a LED.
So I came up with the circuit that is shown above.  When I showed it to some people they told me that it is a terrible idea to do so without any explanation and looking at  me like I am an idiot.
So far the transistor works as a current limiter, it limits current to lets say 20mA perfectly no matter what LED Vd is. It is always going to be the desired current. One problem I ran in to is that a transistor now has a current depending on Vd from its base to emitter. Which again puts me in a situation where I need to mathematically express that and again there is no such a way to do so, because of too many factors I can't control - for example, manufacturing process.
Why do I need such a precision  ? I am trying to make LED that displays a color. RGB value. So for example 0.00007843137 Amps is Red = 1 and 0.00015686274 Amps is Red 2 (8 bit colors).
My question is how to precisely express this voltage drops in a transistor or LED in order to manipulate  such a small current.


texts: Cannot connect microphone using audio jack

texts:
I have a microphone and a female 3.5 mm audio jack. I want to use the jack to get the signal from the microphone for a project with an arduino. To test if the microphone works or not, I'm trying to connect it to an oscilloscope, however no signal from the microphone is received, all I see is noise.
[

[

There are no problems with the individual components. I set the oscilloscope range to be low enough. Can anyone suggest why I'm not receiving a signal? Am I not wiring the microphone correctly?
This is all from a guide on how to connect a microphone to an arduino:
https://www.instructables.com/id/Arduino-Audio-Input/
My schematic is a shortened version of the one on that blog.


texts: power consuption of internal 32kHz RC oscillator

texts:
I am looking for the typical power consumption of the OSCULP32K (Ultra Low Power Internal 32kHz RC Oscillator) of ATSAMC20J18A. Found nothing in family datasheet so far, only XOSC32K. Can I expect the RC oscillator to draw even less current than crystal one?

Background: I'm migrating an AVR project to SAM C20. The former uses a dedicated Maxim Dallas DS1337 RTC (typical timekeeping current 425nA). So my plan for SAM C20 is

a 32.768kHz crystal on XOSC32K
clock the RTC from OSCULP32K when on battery
wake up periodically, say once a minute, turn on XOSC32K (External 32 kHz Crystal Oscillator) and adjust OSCULP32K calibration.

I just need to be reasonably confident that the timekeeping power consumption is going to be about the same or better than DS1337. No precise specification to match, luckily.


texts:
If I want to make changes in the pipeline of MIPS CPU like:

In Mem stage, ALU operator (add, sub and like this...) write the result to the destination register, while load and store stay the same as before the changes.
WB stage is only for load operator that write to the register.

What do I need to change in the data path of the CPU?
The forwarding of the hardware will affect?
thanks!


texts:
I am struggling to understand how the jumpers at the bottom of this diagram change the voltage of the circuit in this diagram.  The input J1 is a 9V wall wart.

By my understating the MOSFET only amplifies current, not voltage, so how is the output changing with the jumpers?

Edit: I understand now that the transistors are working as an amplifier to give a negative voltage potential to the FET. I am now struggling to grasp how the current changing from the FET changes the output voltage.


texts:
I am trying to take the result of a module and assign it to an input of another module, however I keep getting an error about declaring net types. I feel like I'm missing part of the syntax rules here, but I've been unable to find a solution. Any help much appreciated!

Some nonsense code to demonstrate:

module m1(SW, LED);
  input SW;
  output LED;
  reg [3:0] out;
  reg [1:0] x;

  assign x = out[1:0];
  moduleA mA(.in(SW), .out(out));
  moduleA mB(.in(x), .out(LED));


texts: Why do series resistors have a single current running through them?

texts:
In a circuit such as the following:

The current is the same through all the resistors and is:

V = IReq
9 = I (R1 + R2 + R3)
9 = I (100 + 300 + 50)
9 = I * 450
I = 9/450 or 1/50 Amps

Why is this the case though? For example, why wouldn't there be three or four or two current running through the circuit? Why is all the current equalized with the circuit? Note that I'm looking more into the why (perhaps physics?) behind why this happens and not just so much a link to Ohms law or something.


texts: Gate capacitance vs. Gate charge in n-ch FETs, and how to calculate power dissipation during charging/discharging of the gate

texts:
I am using a MOSFET driver (TC4427A), which can charge a 1nF gate capacitance in about 30ns.

The dual N-ch MOSFET I am using (Si4946EY) has a gate charge of 30nC (max) per fet. I am only considering one for now as both on the die are identical. I am driving the gate to 5V. (It is a logic level fet.)

Does this mean I can apply Q = CV to work out the capacitance? C = 30nC / 5V = 6nF. So my driver can turn the gate fully on in about 180ns.

Is my logic correct?

Gate resistance of the MOSFET is specified at a max. of 3.6 ohms. Will this have any effect on the calculations above? The driver has a 9 ohm resistance.

Is there any significant difference for when the gate is discharged instead of charged? (turning off the fet.)

As a side question, during the 180ns the fet is not fully on. So Rds(not-quite-ON) is quite high. How can I calculate how much power dissipation will occur during this time?


texts: How to create copper split rings on the top layer (Eagle)

texts:
I am just a beginner at using Eagle, nevertheless have spent considerable time trying to figure out how to create double split rings with copper tracks in Eagle. Is there an easy way to do so (image 0 below of what I want to do)?

I have tried the following methods, to no avail.

Using the circle tool - cannot edit the circle to form the split with polygon cutout or tRestict and cannot assign signal name. The circle is treated as an uneditable shape.
Creating circles with the polygon tool - I created a circle with the polygon tool by alternating between wire bend style 0 and 4 and making the polygon solid. I then did the same with a polygon circle of smaller radius and set it to cutout polygon. The problem with this is that I cannot place my smaller split ring within the cutout region of the inner larger split ring.
Using the arc tool - I could make the shape of the ring, except when I try to cut out the split it behaves the same as the circle - it is uneditable (polygon cutout & tRestrict rectangle do not react with the arc).
Single solid polygon, using tRestrict - this is the closest I've come to as a solution, where I use circles in tRestrict to cut out the spaces between the solid rings. Problem is, the boundaries of tRestrict form really jagged edges, and I need it to be smooth (as it is a resonator).

I have spent far too long trying to figure this out and am currently at a mental block. Any help would be appreciated.

Link to images showing different attempts in eagle described above:

Attempts in Eagle: Gallery


texts: Mismatch between RTL-level simulation and post-synthesis simulation using xilinx xst

texts:
I have written a verilog code and RTL simulation is working fine. After this I synthesized the design using XST tool in Xilinx ISE 13.2. The post-synthesis simulation is showing some unexpected results. I don't know what went wrong as there were no warnings during simulation. What should I do now? Is there any way to debug post synthesis level netlist? How can I know what my synthesis tool (XST) is doing with my design?
I have included part of my source code. It is for control FSM of my design.

always @ (posedge clock)
begin
case (state)   // s0, s1, s2, s3, s_reset are parameters
s_reset:
        begin
            if(start_proc)
                state <= s0;
            else
                state <= s_reset;
        end
s0: begin
            pixel_value <= dataOut_bigimage;
            pixel_ref <= dataOut_smallimage;
            j <= j+1;
            if(j==1'b1)
            i <= i+1;
            if ({i,j} == 2'b11)
                if(base_col == 3'b101)
                begin
                    base_row_prev <= base_row;
                    base_col_prev <= base_col;
                    base_col <= 3'b000;
                    base_row <= base_row+1;
                end
                else
                begin
                    base_col <= base_col+1;
                    base_col_prev <= base_col;
                    base_row_prev <= base_row;
                end

            state <= s1;
        end

s1: begin
            if (pixel_value <= pixel_ref)
                accumulator <= accumulator+1;
            else
                accumulator <= accumulator;
            if({i,j} == 2'b00)
                state <= s2;
            else state <= s0;
        end

s2: begin
            if (accumulator > 2'b01)
                begin
                    matchcount <= matchcount+1;
                    rowmatch[matchcount] <= base_row_prev;
                    colmatch[matchcount] <= base_col_prev;
                end
            accumulator <= 2'b00;
            if (base_row == 2'b11)
                state <= s3;
            else
                state <= s0;
        end

s3: begin
            task_done <= 1'b1;
            state <= s3;
        end

Every thing inside the always block is of reg data type and is properly initialized in a separate initial block

Thanks in advance


texts: Simulating the discharge of a condenser using CircuitLab

texts:
Intro:

While studying for a Signals and Systems exams for tomorrow i decided to simulate an exercise and prove my answers are right.

simulate this circuit – Schematic created using CircuitLab

What is it about?

The exercise is to calculate the voltage and current at the inductor L1 when time is t=0 and foward (t>0).

(The exercise asks for more but for the shake of simplicity i shorted the question)

The capacitor has been charging for a long time (t<0) so we say it has a charge of 5volts.

How can i simulate the discharge of the capacitor when the switch changed position?


texts: Factoring duty cycle into battery design, give battery life

texts:
I have been given the following scenario:
LED output:
•   assume 200 communication codes per 24hrs, and that each of those LED code words take 20msec of processor time to communicate
BLE:
•   connect to devices and then only communicate when it is time to send LED codes.
•   use a menu traversal to re-start the link, BLE communicates the data to pass on the LED and when done LED comms to pass acknowledgement back to Smart Device.
            Idle Current        Active Current          On-Time (per day)
LED             0                 30ma                 200 uses @ 20msec
BLE             0                 20ma                 201 uses @ 50msec
Processor    100uA                130ma                all the time

processor is 3v input
Battery should last 15days

Since rechargeables have approx. 80% capacity end of life and 80% capacity at -20oC.

Therefore take Estimated battery as 60% of its rated value.

I am abit stuck in how I would calculate the estimated battery size in mAh, since the duty cycle is not given.
The duty cycle fomrula im am using is:
duty cycle% = (Ton/(Ton+Toff)) *100

duty c=  (200*20e-3 + 201*50e-3)/ ((200*20e-3 + 201*50e-3)+86400secs) *100

I'm getting a value of 0.46% which I'm not sure is right.


texts:
I know that fly by DMA controllers (such as Intel 8257) are basically rewiring the circuit and arbitrating the flow of data.

On the other hand the flow through ones keep some of the data into its internal buffer (such as the one in STM32F4 controller).

I wonder which of these techniques for implementing a DMA controller is better, why and which is used nowadays?

In my opinion it is better to just rewire the circuit and control how the data flows directly on the bus, even though if the DMA controller is faster in transferring the data it would be better to first buffer the data and then send it.


texts: joule heating - transmitting power at higher voltages reduces resistive loss?

texts:
electrical engineering hopeful here.

Can someone explain with math how transmitting power at higher voltages reduces resistive loss?

I know Joule's Law

Power  is proportional to (I^2)*R

lets say we have two identical direct current power lines - 1000 feet and resistance is 2 ohms.

One wire will run at 1,000 volts, and the other 10,000 volts. if both have a load of 500 watts, how can it be shown that the higher voltage line with experience less heating loss?

my botched attempt to solve this - I know half of every step i make is probably wrong:

wire 1: 1,000v
load = 500w, so 500w/1000v = .5a = appliance amps
1000v/.5a = 2,000 ohms
2000 + 2 = 2002 ohm serial resistance.
1000v/2002r = .49a circuit amps (less current

wire 2: 10,000v
load = 500w, so 500w/10,000v = .05 ohms = appliance 2 resistance.
.05 + 2 = 2.05 ohm serial circuit resistance.
10,000/2.05 ohm = 4878a * 10,000v = 48,780,000 watts


texts: How to test if a capacitor is good if my DMM farad's range is less than the capacitor's

texts:
So I found out that my DMM maximum reading is 100uF (Though its price is twice the ones that reads upto 100mF, mostly because its 8 years old). It doesn't have manual range for capacitance measurement, it's auto range (From 50nF to 100uF).

Now I have capacitors (that I need to check) their values starts from 100uF : 470uF. When I tested a new capacitor (100uF 16v) it showed me 0.18nF, when I tested a used capacitor (470uF 450v) it showed me 0.18nF too.

How can I tell if they're good using other DMM tests?

P.S: None of them are bulging, still they could be bad, that's why I need to check their readings.


texts: How can I convert the output from a momentary switch to a pulse on push and a pulse on release?

texts:
The title pretty much says it all.

I have an idea to try out involving a op-amp differentiator circuit and a diode bridge, but I am flying blind.

Also I am trying to accomplish this without a micro-controller.


texts:
We have got a 20W led ,RGB from a good seller in China.

I have a few questions regarding the led (see the attached image)

Is there a data sheet to this Leds? something generic ?
How can you know where are the RGB pins, and the voltage pins ?
I tried to understand how are the control lines are working, and i was thinking that like any other led strip the control lines are only connects the RGB lines to ground, with a high current N-CHANNEL FET .

The seller told me this :

R:14-17V       G:21-24V         B:21-24V
 R：1150mA-1400mA   G：800-950mA  B：800-950mA

Is it means that the control lines are with these voltages ??

Please see the attached image.
thanks very much.


texts: Use PSU as replace for broken source +12Vdc 3.33A?

texts:
I need 12Vdc 3.33A source power for Silicon Graphics 1600sw display, I have two ATX computer power supply. Is it possible to use these PSU as replace for broken 12Vdc 3.33A adapter ?
UPDATE: I connected the 12v 35w halogen lamp for provide a small load to +12 VDC(Yellow) and Ground(Black), then I turn on the PSU by shorting the PS-ON#(Green) and Ground(Black), DCV show about 11,43 V, so I connected the monitor and it works!


texts: Does an Input Resistor Negatively Impact the Transient Response of a Linear Regulator?

texts:
To minimize regulator power dissipation in cases with a large input/output voltage differential, many linear regulator application notes suggest adding an input resistor to dissipate some power external to the regulator.  An example from the LT3083 datasheet is shown below, where Rs is the added input resistor.

Since the resistor causes the regulator input voltage vary with load current, the output transient response of the regulator could be affected. In general (i.e. for all linear regulators, not the one pictured as an example of an input resistor on a regualtor), assuming that the resistor is sized to meet the regulator dropout requirements at maximum load, does adding an input resistor negatively impact the output transient response of a regulator?  At what point, if any, does the impact become significant?


texts: There is an electrical component called voltage release, and shunt trip release . what are those and what do they do?


texts: How would I go about measuring an analog signal that has both positive and negative voltages on an arduino analog pin at a high sampling rate?

texts:
I have a signal that fluctuates between -70mV and 50mV. How would I get the arduino mega to read this on an analog pin at a high sampling rate? Ultimately I am trying to graph the data in real time so it looks like this.

I have looked at the question posted earlier on EESE about reading positive/negative voltages and it gives info on a slow moving signal that ranged from -55V to 55V. I doubt this solution would apply to my situation though (attenuating signal with two resistors  and then offsetting the range by using an op-amp summing circuit).


texts: Pulsed DC, kA range inductive transient protection method

texts:
I would like to design a transient protection solution for HVDC_pulse_unit.

HVDC voltage = 3500V , current > 40kA.
Events:
D1 flyback diode survives(50kA surge forward current).
MOVs section did not trigger (1200j, Varistor voltage = 5400V).
D4 12x low power serial diodes (300mA, 16kV each) rated 192kV burned.
EDIT:D4 is placed wrongly on the circuit. It protects the rectifier bridge of the charger inside the pulse unit. It was mentioned to acknowledge the magnitude of the voltage spike. Please ignore it.

Possible solutions:
Op1 - Using  RC Snubber method for 3kA pulses (picture below), R C values where computed. The problem is voltage rating for C1. If D4, rated at 192kV  failed how would a snubber capacitor survive?

or

Op2 - Would "normal" 1500W peak power TVS diodes survive until the varistors start to conduct?  A small inductor in series with the TVS diode in order to limit the current rate of change?

Are the two solutions viable? If so, which one is better? I have no formal schooling in electronics, so all kind of errors might plague this post. Thank you.

EDIT:
I did a few tests (below 10kA) using TVS, 10 bidirectional  1.5KE400CA in series. Breakdown voltage 400V per diode. Still got 8kV voltage spikes (picture below, x100000 attenuation)


texts: How to decrease capacitance of PIN photodiode

texts:
I am using PIN photodiode BPW34 (1).

I am then using an opamp (LM324) (2) to amplify and get an output voltage from the current source generated through the photodiode.

Following is the circuit I am using to realise this.

Following is the output I am getting at particular frequencies. I am actually giving square wave input light signal to photodiode.Following image is the output we got from the digital oscilloscope(Left-400kHz,Right-2kHz).

I also tried changing parameters for Cf in the diagram and also putting direct square wave voltage source(Left image) instead of photodiode with equivalent resistance.

Following is the output I got.

After all the experimentations, I feel that frequency response is sluggish(Right image) due to RC limitations of the circuits and that too due to capacitance of photodiode.

Someone please suggest me something for the same. I have read a lot of documents related to the same but couldn't find anything that is concrete.


texts: Analogy to explain why an antenna must be (in order) size of wavelength

texts:
An antenna has to be sized on the order of the wavelength because we want waves to form. Waves mean, very roughly speaking, different "state" (current, voltage, water level, ...) at different locations at different times.

This means that the structure must be long enough such that the signal propagation is visible. If the signal would propagate infinitely fast, it would change as a function of time only but not as a function of location. No wave forms.

Alternatively, the signal propagation speed must be slow.

I am looking for a good analogy to explain the latter (reducing propagation speed reduces required structure size) to a non-technical person. I was thinking about a swimming pool and the comparing it to one with oil. However, I do not see how I would convince someone to imagine creating a 1m wave in a 1cm pool ;-)

I expect this question will generate a lot of answers. I emphasize that I am only interested in completely non-technical (and not necessarily perfect) layman analogies. Available videos or animations would make it even much better.


texts: Does it matter if power is applied only instantaneously?

texts: If I build a railgun and apply say, 1 million watts, to the circuit to try to power a projectile forward through electromotive force, will it really matter if that 1 million watts of power is applied for just an instantaneous time say, 1 picosecond? Will that massive amount of power even going to matter to produce any significant work, assuming nothing will get welded in place as result?


texts: Triacs Turn off time - can it be faster?

texts:
I am making a phase controller to adjust speed of an AC motor. I use BT139-600E triac to switch AC voltage and MOC3052M optocoupler without zero-cross to turn triac on. It works fine, even without noise back to AC line, because I added two LC-filters.

Anyway, I see oscillogram is not so good. As I see, it takes about 800µs to turn triac off. That's why it won't turn off at zero-cross, but about at ±80V. Is that because of the snubber RC-circuit?

So the question is:
Is there a way to make it turn off faster? Or maybe you can advise other specific triacs for this task? To play with snubber circuit?

I use the usual scheme to control triac with snubber RC and varistor.


texts:
Does anyone know if i can connect 2 FSR in series and then in parallel to a fixed resistor, creating a potential divider circuit.
Given the inaccuracies and low repeatability of force reading from one FSR, would connecting 2 FSRs in the above arrangement cause even more problems?


texts:
Assuming we have a transistor that can bear 400v 0.3A, is that means it can bear 30A if we used it for 4v only or it always withstand 0.3A?
(since P1 = P2 = 0.3 * 400 = 30 * 4)


texts: How to power a widget, while the li-ion battery is charging?

texts:
I am in need of a way to charge a 3.7V li-ion cell (probably an 18650 type) from a 4.5V - 20V input. That's not a problem, there are plenty of (switching) battery chargers around with that kind of operating range.

However, my difficulty now comes from the second requirement. The widget must be able to operate while charging drawing on average 250mA with 500mA peak load when the motors are operating.

Whilst in principle it sounds like all I need to do is draw current from the battery, this would interfere with the charging process, because the current measured would be different to what the battery is actually drawing. When in the constant-current stage (~90% of the charging process time) the current changing suddenly would alter the charge voltage. This probably wouldn't be too healthy for the battery. It's also likely to interfere with the C/10 cut-off.

What would be the best way to solve this problem?

I thought about using two ICs. One to charge the battery and a buck converter to run the electronics at ~4.5V, but this takes up space, and increases the cost of the widget, so I'd rather do it another way.


texts: MAX10 .pof file issue, quartus II and usb blaster

texts:
After a MAX10 board revision. When programming the MAX10 with .pof, the MAX10 board do not start when power-on or after .pof programming is completed. However, normal operation is achieved when programming .sof.

Some of the configuration pins are used as I/O, and appropriate check-boxes were set in "devices and pin options / general".

Now looking closer to the datasheets, it seems those check-box settings are ignored during power-on sequence. So it appears that many pins still requires specific pull-up/down at power-on. Some of them appear more critical than others because schematics found on google have different treatments for configuration pins.

The documentation is confusing me when it comes to the custom configuration pins, for example: in the max10_IO User Guide, it seems explicit nConfig, nStatus and Conf_done pins need to be pulled-up or driven high (vccio).

However, in "Intel MAX10 FPGA Device Family Pin Connection Guidelines", it is said that nStatus is driven low by the device during initialization.

In the example of nStatus , why would they recommend this pin to be pulled-up or driven to 1 if the device drives it low during initialization anyway.
In the example of nStatus , why would they recommend as alternate option to drive the pin high with external driver, this would result as a bus conflict if the pin is driven low during initialization.

Currently on our board:

nConfig(E7) : n/c
nStatus(C4) : i/o, tristated at boot
CONF_DONE(C5) : i/o, tristated at boot
CONFIG_SEL(D7) : n/c
JTAGEN(E5) : i/o, driven low or high at boot
TMS/TCK/TDI/TDO : n/c if no programmer connected

Then:

Based on the above. Any obvious mistake in our current board layout that would prevent the device to start at power-on?
Any other configuration pins not mentioned here that would be critical?

Some additional details:

This is a 8 layer PCB so unfortunately difficult to patch or probe.
It appears that some of the MAX10 i/o pins are pulled-up by the MAX10 itself after power-on.
We can program .SOF anytime using JTAG, MAX10 would immediately start.
Higher than usual power consumption, MAX10 is warm (never happen in normal operation).

Thank you very much.


texts: Explaining high voltage inverter principle (KIKUSUI COS5020 oscilloscope)

texts:
I'm trying to fix KIKUSUI COS5020 oscilloscope HV part. Here is the schematic part:

Failed parts were: transistor Q651, capacitor C655. At high temperature were resistor R657 and inductor L650 (both not damaged completely). I have replaced them, also U651. T651 seems to be ok - tested. But the schematic still doesn't work. Can someone explain the working principle of this inverter?

DC at J-32 is about 18V as should be.

Q651 transistor voltages:
B 1,28V
C 17,6V
E 0,73V


texts:
For a new project I need to connect two boards via PCI express. For space reasons a custom cable assembly would be the best solution. But I'm not sure what is the best way to go here.

I've seen Riser-Cards with simple ribbon-cables. But when I think about
differential impedances etc. these solutions do not seem to be very promising.
I've thought about a 2-layer Flex-PCB with a solid ground-plane.
With some calculations I should be able to have the proper
impedances for the high speed signals.

Is there any suggested way to handle this?


texts:
I am pretty new to designing amplifiers, but I have been playing with LTSpice and came up with a schematic, however I am not sure how to reduce the THD of the circuit. For 1kHz, I get the following from SPICE
Fourier components of V(out)
DC component:-0.000101871

Harmonic    Frequency    Fourier    Normalized   Phase      Normalized
 Number       [Hz]      Component    Component  [degree]    Phase [deg]
    1        1.000e+3    2.324e+0    1.000e+0    -179.11°       0.00°
    2        2.000e+3    1.038e-2    4.466e-3      94.08°     273.19°
    3        3.000e+3    4.972e-2    2.139e-2      15.96°     195.07°
    4        4.000e+3    1.017e-3    4.373e-4    -130.22°      48.89°
    5        5.000e+3    1.840e-3    7.914e-4      50.93°     230.04°
    6        6.000e+3    1.001e-3    4.304e-4     174.94°     354.05°
    7        7.000e+3    4.204e-4    1.808e-4      53.16°     232.27°
    8        8.000e+3    6.834e-4    2.940e-4    -168.34°      10.78°
    9        9.000e+3    4.017e-3    1.728e-3      80.26°     259.38°
Total Harmonic Distortion: 2.194679%(2.214350%)

Could you provide me with some pointers on how to improve this? Thank you!


texts: Why are chip designers called "triangle pushers"?

texts: I heard chip designers being described as "triangle pushers," the idea being that somehow the logic on the chip was formulated by arranging triangles on the silicon in certain ways. How does this work? I don't understand how triangles can be arranged to create digital logic or why the shape of a triangle would be important.


texts:
I am using LCD EJ080NA TFT with LED back-light.

LM3410 is used as backlight driver.

Schematic as below:

But when I am testing it on hardware, I tried without load and with load.
Without load, IC got damaged since boost converter needs load otherwise capacitor gets charge continuously and don't get feedback path for discharge.

If I connect dummy load, R23 value will change as it decides load current. If someone test it without load ( without LCD TFT connector plugged in) each time it will damage LM3410 IC.

So what is the safest way to test and implement above circuit?

Thanks in advance.


texts: Here is a bad diagram of a project I’m working on. In a beginner to EE and this stuff. I have a laptop display connected to a controller board I got on eBay. It has a input of hdmi and a dc power jack 12v 2A. I want to convert it to usb c so I can power and transmit date from my laptop. Building a custom board is to hard for me. I’m thinking I can get a breakout board and wire the Vbus and GND and I think the CC1 or CC2 lines to another breakout board on the same pins, then plug the breakout board to a pre made power negotiator zy12pdn and power the controll board from that. For the video transmission I connect the data lines from breakout board to another breakout board on the same pins then use a usb c to hdmi adaptor to the board. The reason I’m using so many breakout boards is I can’t solder the wires to the usb c head.  Would this work? Assuming my laptop will give me the 24W will the protocol and the alt mode for usb work? If you can please provide and information about usb c and maybe after some research I could just make my own custom usb c receiver. Thanks


texts: How to derate a ceramic capacitor for DC bias

texts:
I understand that the capacitance of a ceramic cap is very dependent on the DC bias applied to the terminals.  At rated voltage, I've measured a decrease of up to 70%, and I've heard it can go higher.  That's two datapoints, one at zero voltage, and one approximate value at rated voltage.  For cases where the manufacturer doesn't make the derating curves available, I'd like to be able to estimate the derating required.

From a TDK app-note (app-video?  Do we have a name for these things, yet?), I grabbed this plot.  Smaller capacitance components suffer less capacitance change, higher voltage components suffer less capacitance change at the operating voltage, and (not shown) larger components suffer less capacitance change.

Source https://www.youtube.com/watch?v=weUrWSFJCgk TDK Tech Tube : DC Bias Effect on Multilayer Ceramic Capacitors (MLCC)

Is there a standard curve for this?  Something like how there's a standard capacitor discharge curve, for example.  I'd like to be able to fit to the datapoints and interpolate for an operating voltage somewhere below the rated voltage.  Are there other techniques, short of ordering the component and measuring, to estimate the capacitance at operating voltage?


texts: Significant noise observed on channels of TXB0108

texts:
We're working with a ADC chip test setup that uses the TXDB0108 to step up 1.8V data lines to 2.5V that are connected to Kintex7 FPGA.

The pin-out is as follows:

VCCA is 1.8V, while VCCB is on a 2.5V rail.There are series resistor (value 10 ohm) on each of the data lines on both sides of the level translator.

The sample rate of the ADC chip under test is 2.5MSPS. OE is pulled up to VCCA through a 10 K Ohm resistor. We have 0.1uF bypass capacitors on both supplies. The issue that we are currently facing is that whenever ADC starts conversion and the data is available on the lines we observe high frequency noise that gets coupled to the supply. When there is no data on the channels of the level translator we do not see this noise. To confirm if this noise is coming from the ADC or from the level translator we disconnected the chip board of ADC and supplied a square wave to one of the channels. The frequency of the signal was 2.5MHz and we observed the same noise pattern on the data lines and the supply.

In this image channel 1 is the 2.5MHz signal at the B side of the channel of the level translator and channel 2 is VCCA of the level translator which is 1.8V. We are observing oscillations in the signal.

The image below has channel 1 showing the A side of the channel of level translator which is the supplied 2.5MHz signal from a source and channel 2 showing the VCCB of the level translator which is 2.5V. The noise appears on both supplies as well.

As you can see there is significant noise that appears on the signal which is getting coupled to the DC supply.

Now we had previously installed 0.1uF bypass caps close to the level translator for proper operation but after observing this noise we soldered 10nF in addition to the 0.1uF caps. To our disappointment there was no improvement seen.

We need your help to remove this noise as this is reducing the SNR of the ADC chip. Please let us know if you need any more information. Urgent help would be appreciated.


texts: How appropriate are the open source licences currently in use for inclusion of HDL cores in a commercial product?

texts:
HDL IP cores targeted towards ASICs, FPGAs or both are often very useful for adding functionality to a project quickly. Commercially licences cores are available from many sources for a range of prices, but increasingly "open source" cores are becoming available which provide similar functionality.

The use of free and open source HDL cores is especially significant for FPGA-based hardware projects. The low initial hardware costs of FPGAs means that this is a market where development of custom cores for commonly used functions can have a large impact on the total cost of a project.

However, currently there are no open source licences specifically designed for licensing HDL cores and therefore a number of licences designed for other uses (primarily software and physical hardware design) are in use in practice. The use of these licences for HDL core seems to me to be questionable and I worry about including open source cores in commercial projects with current licensing arrangements.

My question is how appropriate are the open source licences currently in use for inclusion of HDL cores in a commercial product?

In particular,

is an HDL IP core applicable within the terms of the licence?
is commercial use allowable under the licence?
what attribution requirements are included?
is it certain that designs including the licensed cores are not required to be disclosed as 'derived works' etc?
is the licence used widely enough to be well recognised?

Some licences currently in use are:

LGPL (preferred on OpenCores)
[Modified] BSD licence
CERN Open Hardware Licence
TAPR Open Hardware Licence
Creative Commons licences
Solderpad Hardware Licence
Open Hardware Description Licence

There's a few discussions of this already online that I've looked at (see below), but I'm not sure any have come up with anything conclusive. Especially interesting is LGPL as it's used a lot in industry for software libraries and there's a large number of OpenCores cores available under the licence.

Of course I'm not expecting anyone to commit to a concrete legal opinion, but something better than "no one will find out anyway" or "the only way to be sure is to ask the author directly for permission" would be useful to me.

Previous references/discussions:

http://en.wikipedia.org/wiki/Open_source_hardware
http://opencores.org/forum,Other,0,4439
http://www.shareable.net/blog/how-to-choose-an-open-source-hardware-license
http://www.embecosm.com/2013/11/20/softcores-for-fpga-the-free-and-open-source-alternatives/
http://www.ladyada.net/library/openhardware/license.html

Best licences for Open Hardware was a similar question aimed at pure hardware, rather than HDL cores.