texts: Transfer Function Identification from Impulse Response

texts:
I'm working on a system involving a stepper motor that is used for moving a carriage back and forth in a linear motion. I have recorded the response (i.e. carriage position vs. time) corresponding to a single motor step. This, I believe, is what one would call the impulse response of the system:

In order to simulate the response to several consecutive steps, and to develop speed control strategies, I'm looking for a way to convert this time-domain impulse response into a frequency-domain (Laplace) transfer function of the form num(s) / den(s), if possible using open-source tools like Scilab or Python. What's a pragmatic way to do that?


texts: Average Power of load conected to an Ideal Transformer

texts: Where does the 1/2 come from in the power equation?


texts:
I'm working in a project, which will show an arithmetic result as a 7-segment,

I know how to do a one digit 7- segment on logisim,

but this makes the result limited from 0 to 9, and my project highest number can be 999,

so, what is the way to create the three 7-segments and connecting them together to make them like

"hundreds    tens    ones"

any idea, hints?


texts: Getting weird characters in hyper-terminal on serial connection of PC and Atmega-16

texts:
I have a Atmega-16 based board, connected via Max232 to pins 2,3,5 of a db-9 connector. The connector connects to a PC.
I am getting weird characters on hyper-terminal instead of normal "Hello World" for the serial test program. I have set both baud rate in Atmega-16 as well as hyper terminal to be 4800.
I am not getting any faults. Please help.
Thank you!
Edit: I am using this kit : http://roboshop.nextsapiens.com/index.php?route=product/product&product_id=55
The Serial pins of the Atmega16 are routed through a max232 to db-9, the circuit is same as this one:

The settings on terminal are:
Data bits: 8
Stop bits: 1
Parity: none
Baud rate: 4800
The bascom code is:
$regfile = "m16def.dat"
$crystal = 2000000
$baud = 9600
Config Lcd = 16 * 2
Config Lcdpin = Pin

Cls

Cursor Off

Dim A As String * 1
Do
  A = Waitkey()
  Print A
  Cls
  Lcd A
Loop

End

The problem can further be viewed as: http://i.stack.imgur.com/dmnJo.png
The images showing the characters(10) i am receiving are:

and the corresponding hex code that i am reciving is:


texts: How to calculate current in this circuit?

texts:
update:

How do I calculate current in this circuit if switch close at t=0 and the circuit initial conditions are \$IL1(0)=2A\$?


texts: Calculate electric field from wire with AC current through

texts:
Here an experiment picture

The wire(with some resistance) connected to 220 V 60 Hz AC voltage source. The peak current through wire is 0,3 A
How to calculate mean, or at least peak electric field strength value at some point from wire?
I have the next plan:

Consider the dynamics (of current, em wave, etc.) as a series of statics.
Find magnetic induction value, using Bio-Savant formula for few currents value.
Considering, that I know how fast current(and hence magnetic field) changes (half period is 1/60/2 seconds), I can calculate the $$\dfrac{dB}{dt}$$
From first Maxwell's equation get rot E
Hope that, having rot E value, the actual E value can be funded, because my vector algebra is bad..

Is my plan good? How to calculate electric field near wire with AC current throught  ?


texts: LM2596 based buck design doesn't deliver power and heats up

texts:
Disclaimer: I don't have an electrical engineering background, just a hobbyist.

I'm trying to build a buck circuit to power an ESP-2866 and neopixel LEDs for a project. I'm using the fixed 5V version. The LEDs are powered from 5V and there's a 3.3V linear converter downstream that delivers power to the micro. I've followed the datasheet parameters and also simulated the circuit with TI's Webench. But I can't get it to work. I get no output from the LM2596 and both the IC and the inductor get extremely hot. The parameters used are:

Input: 10V nominal (12V max, 9V min)
Output: 3A max (but this is just peak, the LEDs are off most of the time)

This is my schematic:

And this is the layout of my PCB (top and bottom):

Summariezed BOM (all recommended by Webench design):

L1: Coilcraft MSS1210 AEC-Q200 33 uH 20 % 5.9 A
C_IN1: 16volts 39uF ESR 27mohm
U5: LM2596SX-5.0/NOPB
D_REG: 200V 10A 900mV @ 10A DPAK Schottky
C_OUT1: 4.7uF ±10% 10V 1400 mΩ @ 100kHz -55℃ ~ +125℃ CASE-A_1206 Tantalum
U4 and C8 are the 3.3V linear converter and it's input filter cap.

(Side question: does it make any sense to have a filter cap after an output filter cap? And should I isolate the buck with a diode here?)

I've tried to have thick traces and keep them short. The LM2596 ICs, the caps and coils were from Mouser. I've tried replacing them in case I fried them soldering or testing, but nothing. I even tried a different LM2596, one from XLSEMI in case I got a batch of bad ones and still no dice.

I don't have any shorts (that I've been able to find). Pin 1 recieves 12V fine (12.3 in fact, a bit high but within tollerance?), but the output on pin 4 is 0.3V. I don't know what else to test or if it's just an error in my layout.

I'd appreciate any pointers or help.


texts: What can be the consequences of charging a lead-acid battery with an excessive voltage?

texts:
In my field-operating device I use a simple PWM step-down to charge a 6V 3.9Ah lead-acid battery from a 5W solar cell with a voltage of 7.2V. Unfortunately the DC regulator got damaged today and the battery is charged at 8.6V, that is 1.1V above the limits specified by the battery manufacturer. At the sunny days the charging time is approx. 8h.
I have no access to the device, I cannot fix it right now.

My question is: what can happen to the battery, can it explode, set on fire?

I use three 1.3Ah batteries connected in parallel.


texts:
My question was simply. If a meter of wire has impedance of 1 uH. What is the impedance of a meter of bus bar?

yesterday:

To make it simpler.

The longer the leads of SPDs (Surge Protector Device) to load, the larger the inductance and larger the let through voltage at the load.

I'm trying to understand (or compute) what would happen when the leads are not just wires but they pass through the bus bar or terminal lugs. Remember in whole house SPD, you install it at one of the breaker load side especially at the top breaker near the main breaker (reason is to make the shunt shorter for lower inductance and lower let thru voltage). What if (for sake of discussion), it was installed far from the top breaker or in the bottom breaker. The path or equivalent lead length would be like longer and would pass through the bus bar cooper. Would this increase the inductance?

Or imagine the whole house SPD unit leads are not made of wires but composed of bus bar cooper (or imagine you just replace the wires with bus bar cooper). How would it behave?

Playing with this online inductance calculator. I tried bigger diameter wire. The inductance actually decrease. Why does it decrease for bigger diameter wire? Does it mean for bus bar, the inductance induced is actually lesser than passing through wire of similar length or even when it pass through terminal lugs?

http://chemandy.com/calculators/roun...calculator.htm

Original:

Consider the following SPD connected to the panel:

Below the main breaker are lead terminals (shown in green) connecting directly to a 240v-120v step down autotransformer powering the Siemens GFCI breakers 120v circuitry directly (I don't have neutral in the building to avail of natural 120v).

If the SPD wires from outside the enclosure at left passes through the top left breakers load side passing through the bus bar. What is the impedance compared to if the wires would be connected to the transformer leads (shown in green) at the terminals directly?

According to the reference below. For high-frequency currents, impedance per unit length of wire is about 1 uH/m.
How about when it passes through a bus bar? What is the impedance and how is the length or area determined?

https://www.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/content/live/FAQS/277000/FA277471/en_US/Surge%20protection%20devices%20SPD.pdf


texts: Is over-volting a motor just a little bit likely to affect its lifespan?

texts: So, I have a DC marine water pump. It's typically rated for "12v" lead acid batteries, so it should be designed for around 13.5v. I am going to be pwming it and monitoring the current, with a base voltage of around 15.5v. Is this likely to significantly affect the lifespan of the motor?


texts:
What is the point of the body terminal in a MOSFET?

If we assume Vsource=0 and Vdrain>0 then we will have a linearly changing voltage from drain to source. Then if Vgate>0, depending on the difference between Vgate and the voltage on each point in the MOSFET below the gate, we might, or might not, have an inversion channel.

So what is the actual purpose of the body being connected to source? Why don't we simply let it float? I know that if the body voltage is different than the source voltage, the threshold voltage will change, but what if the body terminal is left to float?


texts: Modifying a digital LED thermometer kit to drive larger 4" 7-segment LEDs?

texts:
I'm interested in building an LED digital thermometer with 3 or 4 large 4"/100mm 7-segment LED display digits (for example, Kingbright SA40-19EWA).  There are plenty of kits available which come with smaller LEDs (e.g Conrad, Canakit).  My question is, what's the likelihood of success attempting to use any of these kits to drive larger LEDs instead of the ones they're supplied with/designed to work with?  And if it seems infeasible, would I be better off starting off from an Arduino-based thermometer design instead?  (Although my initial reaction is that an Arduino would be overkill.)  Any other pointers/advice welcome.

The main issue to overcome would seem to be that the large LEDs typically need 7-8V, while 2V is more typical for smaller ones (but maybe some kits are amenable to suitable modification by, say, changing a few resistor values).  Of course there's also other things to worry about such as common cathode/common anode and the mechanics of replacing the original PCB-mounted displays with wires to the bigger digit components which might influence choice.


texts: SPI- Mutiple Slave Configuration - MISO line conflict

texts:
I am using SPI in my design with Single master three slaves ,Using chip select i will enable two slaves at a time.
Is this correct , if no please let me know why ?


texts:
I'm trying to get VGA working on my Altera DE0 board using Verilog, but haven't had much luck. It has the same pins as a normal VGA interface except red, green, and blue are all 4 bits each. Here is the logic I've been trying to use to get a solid color to display:

module solid_color (clk, vga_h_sync, vga_v_sync, R, G, B);

input clk;
output vga_h_sync;
output vga_v_sync;
output [3:0] R;
output [3:0] G;
output [3:0] B;

reg [9:0] CounterX;
reg [8:0] CounterY;
wire CounterXmaxed = (CounterX==767);

always @(posedge clk)
if(CounterXmaxed)
  CounterX <= 0;
else
  CounterX <= CounterX + 1;

always @(posedge clk)
if(CounterXmaxed)
    CounterY <= CounterY + 1;

reg vga_HS, vga_VS;
always @(posedge clk)
begin
  vga_HS <= (CounterX[9:4]==0);   // active for 16 clocks
  vga_VS <= (CounterY==0);   // active for 768 clocks
end

assign vga_h_sync = ~vga_HS;
assign vga_v_sync = ~vga_VS;

assign R = 15;
assign G = 15;
assign B = 15;

endmodule

When I try running it, I just get a message on the monitor saying that this display mode is not supported.

This is adapted from http://www.fpga4fun.com/PongGame.html. However, this version claims to be designed for 640x480 displays whereas my monitor is 1280x1024. Is this the issue? If so, how would I adapt this to fit the increased monitor size? (the clock I'm using is 50 MHz)

EDIT: I added in a clock divider module as follows to change the initial clock signal to 25 MHz:

module divide_clock_by_two(in_clk, out_clk);

input in_clk;
output out_clk;
reg out_clk;

always @(posedge in_clk)
out_clk <= ~out_clk;

endmodule

However, the monitor now just shows a black screen, no message about an incorrect mode.


texts: Mechanical connectors for flexible PCBs?

texts:
Does anyone have a good solution for a mechanical connector for flexible printed PCB, like those used for strips of common-cathode RGB LEDs?

(You can cut the strip across any of the solder pads and scrape back the silicon insulation)

"Just solder" isn't the answer I want to hear (neither is "get better at soldering") as a) I need to do lots of these joins which need to be b) mechanically sound and ideally c) field-repairable, in quite a tough field (on the playa at Burning Man.) The joints need to be mechanically sound as I plan to sew about 30 x 50cm strips into a garment.

Ideally I'd like some kind of screw-terminal. But I don't know what to ask for and can't find one on my own.

Another idea I've come up with is taking 90° header pins and pushing/piercing/drilling little holes for them through the printed track and soldering those in (a much easier task—I've found component-through-hole soldering orders of magnitude easier than wire-to-pad soldering; tracks lift and it's hard to get everything to bloody stay still.) Anyone think this might work and/or tried it?


texts: Why am I seeing voltage spikes on the output of an LM2596?

texts:
I have been working on building a DC/DC converter for an ESP32 using an LM2596.
With a few prototypes out in the wild I'm seeing them reboot randomly.
Having the circuit back on my desk with a scope I'm seeing the output of the LM2596 spike more then I would expect. I have designed the circuit within specifications for the LM2596 with an assumed current draw of between 500mA to 1A.The scope readings were done without the ESP32 connected.

As you can see, with a desktop power supply I'm seeing spikes of up to 3.74V and as low as 3.0V. It seems like this could be causing the issue with the ESP32 as I'm aware that they can be sensitive to input voltage.
I assume my design is causing the issue as when I use an off the shelf LM2596 power board like this one, I'm seeing a much smoother output

I'm considering adding an LC filter to the output of the LM2596 but I'm trying to understand why my design would be causing this much noise in the output from the regulator.

What could I change to address this issue and where is my understanding gone wrong?
Would an LC filter fix the problem or is there a design flaw with the regulator circuit as is?

The board layout looks like this, I omitted the other components in the schematic as I didn't feel it was relevant.


texts:
I need to design a clamp circuit in order to clamp the ringing voltage of a square wave. Therefore, I am planning to use the circuit given below. This circuit belongs to TI however, I couldn't get any reply so far. Could someone please briefly explain me how does the circuit given below operate?

Kind regards,

Mert.


texts: Why do faulty headphones make MP3s sound low bitrate when I touch the wire?

texts:
I have a pair of headphones which came with my phone. They're the standard type that comes with a mobile phone - TRSS 3.5mm jack with an inline microphone.

I was listening to Spotify on my phone. I must have yanked the cable too hard one time and now I only get intermittent sound through the headphones, so I have to move the cable with my finger until I get sound again, so I guess there's a weak contact on one of the wires (as it affects both L and R, I'm guessing the ground)

One thing I'm curious about though - when the wire is in a 'bad' position, the sound doesn't cut out entirely. Instead, the MP3 sounds suddenly as if it is playing at a very low bitrate (horrible MP3 artifacting, barely discernible vocals in songs etc). How is it doing this? I was under the impression that if it's an analog signal, the sound will either play, or it won't, or it will crackle. Instead, it sounds as if something has been digitally adjusted to play at a lower bitrate. Is this something to do with MP3 encoding? And if so, how come I can't hear the low bitrate sounds when the headphones are working correctly?


texts: Missing pins of 16F887 in Proteus 8 schematic

texts: In schematic of Proteus 8, why pin number 11, 12, 31, 32 of PIC16F887 are missing?


texts: Noise power of attenuator-amplifier cascade

texts:
Lets say we have matched circuit that consists of attenuator and amplifier in cascade and that this circuit is subjected to a noise from an outer source whose effective temperature is T. Find attenuation and noise factor of the attenuator.

We know that noise power is given as  Pn=kTB, where k=1.38*10^-23 J/K, T is a temperature and B is bandwidth of given circuit. Now, i found expression that says that noise power of attenuator is

P=kTB=kTBGa + kTaBGa, where Ga is gain of attenuator and Ta is temperature of attenuator, where first part on RHS is power due to noise from an outer source and second part on RHS is noise created inside of attenuator.

I have no clue how this can be true because, based on LHS we could conclude that all we need to determine noise power of attenuator is the temperature of outer noise and bandwidth of attenuator? Can anyone clarify this to me? Any help appreciated!

EDIT:

This is the block diagram i got along with this example:


texts:
I hooked up a Nodemcu module to my 8 channel relay.

The relay.

Excuse the horrible drawing, I didnt find the module in Fritzing. The jumper present in the image is of course not connected in my setup.

Edit and here is a link providing information why I am hesitant to connect the nodemcu GND to the relay:
https://forum.arduino.cc/index.php?topic=440327.0

With the Channels switched on, the relay makes a sound, some kind of soft cracking maybe (continuously). I do not mean the clicking sound when the channels are switched on. If I connect my Arduino Uno clone or my Raspberry Pi in the same manner, the sound is not there.

The relay module is active low.

So, I'm new to electronics, I figured there has to be some distortion. I read about bypass capacitors.

I would put a 1 µF capacitor (or so, I would need to find out what a suitable value may be) where the blue C denotes it, between GND of the MCU and its VCC.

Could this be a correct approach? I'm kind of unsure because the noise would be on the GND rail, not the VCC.

Any other ideas what may cause this behaviour?

Edit

Here are the measurements suggested by  Tony Stewart. EE since '75

+-----+--------+--------+---------+
| PIN |   DC   |   AC   | CURRENT |
+-----+--------+--------+---------+
| D1  | 1.1 mV | 0.01 V | -       |
| D5  | 1.1 mV | 0.01 V | 0.03 mA |
| VCC | 3.29 V | 0.04 V | 0.01 mA |
+-----+--------+--------+---------+

Measurements taken directly from the nodemcu, no relay connected, states set to ON, so the Pins should be low.

Measurement again, with Relay connected, noise was present.

+-----+-----------------+-----------+----------+
| Pin |       DC        |    AC     | Current  |
+-----+-----------------+-----------+----------+
| D1  | -3.4 to 0.09 mV | 8.8-9.3 V | -0.05 mA |
+-----+-----------------+-----------+----------+

simulate this circuit – Schematic created using CircuitLab


texts: Is there any chip that measures the amplitudes of voice bands simultaneously?

texts: Is there any existing chip that can take 20Hz~20KHz signal as input and outputs the amplitude of each frequency band? For example, divide the 20Hz~20KHz range into few bands (20~1K, 1K~2K,...) and outputs all the power/amplitude of each band simultaneously?


texts:
I would like to control an LED with audio signal, but the problem is, that output signal is only 150mVpp (with 150mVpp positive offset). In my understanding, it needs to be higher than 0.6V to get the transistor running, therefore I am not sure what to use instead. Do I maybe need an opamp in the middle? Any tips?

simulate this circuit – Schematic created using CircuitLab


texts: History question - why are logic levels inverted between TTL and RS232?

texts:
I'm just looking for a historical answer as to why TTL and RS232 don't transition logically in the same directions. The signals are the same, but basically level-shifted and inverted.
Was there a technological reason behind this, was it a mistake, or was there hardware that inverted that was cheap and easy to come by to drive the outputs for RS232 communication?
Thank you for helping to satisfy a curious question.


texts: What is the most common type of accelerometers in today's smartphones?

texts:
I know there are 6 different types of sensors for measuring acceleration:

Capacitive
Piezoelectric
Piezoresistive
Hall Effect
Magnetoresistive
Heat transfer-based

I have trouble finding a source that can help me find out what kind of accelerometer that is being used in today's smartphones.

I think it is piezoelectric according to source, but its not a good one. Is there any better source that can confirm this in a more statistical or official manner?

Many thanks for any help!


texts:
I've seen a few stripboards laying around that have no copper tracks. After looking online I can see that you can indeed buy these but I can't seem to find why or how to use them.

How can you use it if there's no tracks to solder too?


texts:
I am currently learning about telecommunications but I have some concept issues.

Firstly, does it matter if I am using cosine or sine in the equation? I understand that they are basically the same thing but there is a phase shift difference between them. Should I account for that phase shift?

For instance if I am making a computer program (matlab) that is going to generate an amplitude modulated signal, should I use cosine or sine?

My equation for the program is as follows:

output = amplitude * (1 + depth * cos(2 * pi * modu * (i / exp_rate)));

Where:

modu is the modulating frequency
exp_rate is the carrier frequency
i is the ith pulse
depth is the depth I want in the modulated frequency

Is it correct?

Note: I am trying to apply amplitude modulation to a train of biphasic pulses. So in the end it should be a train of biphasic pulses going up and down periodically. The amplitude of the ith pulse will follow the modulation waveform and there is no carrier term.


texts: Difference series resonant and LLC DC/DC converter

texts:
What is the exact difference between a series LC resonant converter and an LLC converter. From a topological perspective, they seem to be exactly the same. I believe that for an LLC, also the magnetizing inductance participates in the resonanance phenomenon but I am not certain. Does this only occur when the magnetizing inductance is small compared to the leakage inductance of the converter? Like a factor 10 instead of a factor 100?

Besides, does this difference impact the control of both converters?

Thanks in advance


texts: how to decide which passive component to use

texts:
i am not new to electronics and know the functions of a lot of basic components , but the problems arises when i have to use then because i dont know how to use them , when should i use a 1 ohm resistor or a 1M ohm resistor , 1 picofarad capacitor or a 1 farad capacitor , 1 Henry inductor or 1 microhenry inductor , even when do i use them , i cant design circuits on my own because of lack of this kind of knowledge , what should  i do , get a good book , or there is a page good enough to clear all my doubts , or an expert ca explain me here in the answers ps : im a student in high school.
i have example for problems i face , lets say there is a circuit where several resistors are used , but why do i use the specific resistors , i have a wild guess to match the voltage lower than the maxmimum voltage of the component , like to protect the ic , or bjt , am i correct


texts: Arduino, RGB LED, BlinkM MaxM controller

texts:
I'm a student from QUT doing interaction design this semester (you've probably heard from a few of us over the past few months). Anyway I just order the 25 diffused RGB Leds if that rings a bell for you.

Now onto my project, Im basically building a 450mm3 white perspex cube that changes colour based on sound. On the inside of the cube I intend to build a smaller 5 sided cube structure from circuit borad and attach 4 RGB leds to each side of the inner cube at the corners to maximise the dispersion. I am using Arduino to attach a microphone to read the audio, and i then intend to connect the RGB leds to the pwm. However from what i have found out from my lecturer Gavin Sade, the leds will draw too much power as there will be 20 all up.

His solution was to use the BlinkM MaxM controller chip and connect my own circuit of 20 RGB leds and power according with something like a 5Volt 2am p power supply. I have little money to spend on this project unfortunately and from the looks of it this would be the cheapest way to go as I have already got my Arduino, RGB leds and microphone ready to go.. just need to work out a circuit to control that many leds.

http://www.littlebirdelectronics.com/products/Triple-Output-LED-RGB-Diffused-25pcs.html that is the rgb leds that im using. Ill be using 20 of them in my cube, utilising each colour it that makes any difference. I need to work out the power supply also to maximise the brightness potential of these lights. Also need to know how to set up correct resistors for this setup.


texts: Switching USB connections between two devices?

texts:
I currently have plans to convert a keyboard to bluetooth using a bluefruit module, but I would also like to have a switch to make it wired if I ever want to plug it in.

The bluefruit module is being powered through a USB battery bank and the keyboard's USB connection is connected to the bluefruit's USB passthrough for power and the PS2 data pins. I want to be able to use a switch to cut the data connection (and maybe the power connection?) between the keyboard and the bluefruit and then directly bypass it to the USB connection leading up to the battery bank's charge port.

I'm fairly new to this kind of stuff, but my understanding is that I can't use a transistor because they're not bi-directional, and that there might be some other complications involved with electronically switching data lines due to the way USB devices initially report to the computer, but there are devices that do this kind of thing like the Plugable USB switch, so it has to be possible in one way or another.


texts: Simple AC to DC converter: upper limit for the capacitance of filter capacitor?

texts:
By 'simple AC to DC converter' I mean the familiar circuit shown in the figure below, where the capacitor C reduces the ripple.

A sufficiently large capacitor can be used in order to reduce the ripple voltage to any desired level. But in The Art of Electronics the authors state that this approach has some disadvantages, one of which is

  The very short interval of current flow during each cycle (only very near the top of the sinusoidal waveform) produces more \$I^2 R\$ heating.

I don't understand what is meant by this extract. Does \$R\$ here denote the resistance of the load? What is meant by 'the very short interval of current flow during each cycle'? Does a bigger capacitor cause more wasted energy?


texts:
Basic question that I'm surprised I can't find the answer.  I'm more marketing than micro-engineering  :)

If the processor says is rated to 120 Mhz and the board uses a 12Mhz crystal, is the hardware limited to 12Mhz?  Or it can still operate at 120 Mhz?  Somewhere in between?  Depends on the firmware?

Reason:  The product is exactly as above and I'm writing up the spec sheet for customers.  So am I being dishonest if I say it is powered by a 120Mhz micro in this situation? Or that is perfectly true if the firmware guys make it so?

edit:  The processor is STMicro F205 Cortex M3.  They market it as "120Mhz" but then the datasheet says to use a "4 to 26 MHz crystal oscillator", which our people chose a 12Mhz.


texts: Is it possible to place an SMD crystal on opposite side and connect it through vias?

texts:
To avoid to use very small and expensive crystals I'd like to use a bigger one and place it to opposide side of PCB to save space.

My question is:
Is it possible to place an SMD oscillator on opposite side and connect it through vias?

In my case I've a 4 layer PCB. I'd like to know if this will harm or affect crystal signal quality and if it's used/unused practice.

Here's an example image:

EDIT:
In this example and in my question I refer to a crystal (no oscillator). I've not placed capacitors to have a more clear example. EPSON TSX-3225 38.4000MF10Z-AS3 is a device that I'd like to use.


texts: Is there a DC-DC converter topology that can output positive and negative?

texts:
E.g. Is there a converter topology that can take a 12v input and convert it to -12 to +12v output with respect to GND?

For the record I'd really prefer something that doesn't use rare magnetics.

I could do it using a Buck converter and an H-Bridge on the output, but I'd really prefer a minimum cost/parts count solution.

EDIT: Following some great low-power suggestions, I'm actually looking at converting about 100 to 200 watts. It doesn't need isolation or both a positive and negative rail at the same time, just an output that can be adjusted from -12 to +12 volts. Regarding "rare" magnetics, some topologies use tapped inductors that have two windings of different gauges that often need to be customised specifically for each application. I'd prefer a solution that uses normal inductors or something that can be sourced fairly generically.


texts:
I'm trying to use TI's LMR16006 Simple Switcher Buck Converter to regulate 48V down to 5V on my circuit.

I used TI's WebBench tool to calculate component values for their reference design, and had a board fabricated according to the design:

I hand-soldered a prototype of the board, and was able to get it working after some finicky hand-soldering.  I had some trouble, but assumed that it was just due to poorly soldered joints (since I was hand-soldering a bunch of small parts for the prototype).

Then I had 10 boards professionally made, and I'm finding that they don't function at all.  V_out (across C6) is 1.26 V, and I'm expecting to see 5V!

I checked a couple of obvious things on the nonfunctioning boards:

I checked connectivity across the board to see if there were any bad joints and/or if anything was wired incorrectly, but that doesn't seem to be the issue.
The bootstrap capacitor (C4) needs to have a voltage of at least 3V; in both of my boards (working and not working), the voltage is around 6-7 volts.
I was concerned that perhaps the SHDN pin was being pulled low, but on both boards the value is hovering around 5V, which should be high enough to ensure that the regulator itself isn't shut down.

After looking at them on  scope, it looks like the on the working board, the SW pin is switching at the correct frequency (~700 kHz), while on the non-working board, the frequency is MUCH slower (~150 kHz).

I'm trying to figure out why the converter's not working as expected, but I'm honestly not sure what to investigate next.  Any suggestions for how to proceed troubleshooting would be super helpful.

Edit: Board design uploaded below.


texts: Combined temperature coefficient of LM741 and trimmer pot for null offset

texts:
I want to use a 10k trimmer pot with a 250ppm/°C tempco for offsetting input offset voltage of an LM741 op-amp.

Cermet potentiometer temperature coefficients partially answers my question. And the following goes into great detail about why null offset op-amps are rare nowadays: Modern opamps with null offset.

But I'm asking here, now, to clarify a few things:

how to calculate maximum combined temperature coefficient and drift, given specs of an LM741 and the trimmer pot.
why "you can expect 10-20:1 improvement if you draw negligible current from the wipe"
why "the best approach is to first minimize the adjustment range", and how this might be done. (Is this by "shunt[ing] a cermet pot element with a low tempco resistor? And how would that look in the LM741 application?)

(I prefer using components I'm familiar with, and while I could find one with low VIO offset, it's hard finding one which is as cheap and versatile enough in the ways a 741 is).


texts: BLE emission when disconnected and waiting connection

texts:
I'm working on a toy device that goes into an airplane. It is using a BLE device and yet my knowledge about is a quite limited.
If I understood correctly, usually in protocols: the device advertise, the central connects and communicate. But if a disconnection happens (for instance my phone goes into flight mode), is it possible to be sure that the device doesn't send any data?(no advertising)
And more important: since I've been connected once, can my device just passively wait some incoming data to reconnect ? (the landing is done, my phone is active again. Thus I want to reconnect to my device without pushing any button)
I couldn't find any flowchart explaining this situation. Maybe that are silly questions but I cannot find the answer clearly.
Thanks a lot!


texts: Audible difference between "audio grade" capacitors in the same range?

texts:
The following is a list of prices for some capacitors sold by Mundorf, a massively audiophile-approved component company. Each capacitor is within the same product range ("EVO"), and apart from some differences in max voltage and tolerance (450VDC ~ 1000VDC, 3% ~ 2% tolerance) are all 1µF polypropylene film types designed for use in power decoupling/filtering stages in audio circuits.

1µF Mundorf Polypropylene Film Caps:

╔════════════════════════════════╦═════════════╗
║ Series                         ║ Price       ║
╠════════════════════════════════╬═════════════╣
║ EVO                            ║ €3.50       ║
║ EVO OIL                        ║ €7.99       ║
║ EVO Silver.Gold OIL            ║ €25.90      ║
║ EVO Supreme Silver.Gold OIL    ║ €69.90      ║
╚════════════════════════════════╩═════════════╝

I have little doubt that in a blind ABX listening test there probably isn't a single person on the planet who could consistently differentiate the pricier caps with greater than 50:50 accuracy, and that realistically what is being paid for is some combination of bragging rights and capacitor packaging sexiness (phwoar, look at that black and red one).

I know questions have been asked about whether different types of audiophile caps are anything but snake oil, but specifically my questions are:

Given a single capacitance rating, would it even be physically possible for the human ear to hear the difference between the capacitors within a single "audiophile" capacitor range, as the Mundorf EVO range above? (e.g. swapping the standard "EVO" out for an "EVO Silver.Gold OIL")
Would the difference in audio output even be instrument-measurable, and if so, what metric would constitute an "improvement" in quality? Lower THD? Lower ripple? Increase in pixie dust?


texts: How to edit dimensions for PCB layout in proteus

texts:
I need a relay like this in proteus

http://www.sanyourelay.ca/public/products/pdf/DI1U-K.pdf

the DI1U-P type.

unfortunately all the relay i found are not of the same size.

please help me on how to change measurements in the package.


texts: What is the easiest way I can power multiple dc motors at the same time?

texts:
(inexperienced) I found some 250-500w dc motors that I plan to control with some digital PWM controllers. Only problem I'm running into is that all the dc power supplies I find upon searching are hundreds of dollars, and extremely big and bulky.

I don't have this kind of money. Isn't there some way I can power these motors with a normal DC power supply within the rating limit, such as the ones used to power laptops? Surely there are cheap hobbyist DC power supplies rated for under 1000w? You know, ones that don't weigh 40 lbs?


texts: 555 Timer astable mode, capacitor discharges only through R2, why?

texts:
I'm pretty new to electonics so please bear with me...

I'm looking at a standard 555 timer astable circuit. When the capacitor is discharing, I am having trouble understanding why it discharges only through resistor R2 instead of both R2 and R1.

If I think about the conventional flow of electricity. I imagine a positive charge (I know they don't really move and its electrons that move) going from V+ through R1 to the point just before R2, shown by the red line. As the cap discharges the same positive charge moves off the positive plate towards the same point, through R2.

So here comes my first question. At this point the positive charges would repel, so should one "win" and be able to continue its journey to pin 7, or would both somehow find their way to pin 7?

If they can both find their way to pin 7 regardless of which had the higher potential energy then I think I get it.

But, even if that is true, if I think of real current flow (green lines), electrons moving towards the positive terminal of the source, I run into difficulties. Electrons presumably leave the -ve plate of the cap and run through pin 1 and out of pin 7 to the juntion between R1 and R2. But then why shouldn't the electron pass through R1 rather than R2?

Can someone enlighten me?


texts: How does changing the inductance, capacitance and load in a buck or boost converter affect the circuit?

texts:
Before anyone calls me out, yes I am asking electronics related questions due to homework but honestly I am able to answer some of them. There are just some that I need StackExchange insights. For others, they are admittedly things that I don't know or cannot search easily.
My electronics professor is currently teaching DC-to-DC converters. He decided to drop us some theoretical homework and just postpone the experiment. He gave us some questions. This is one of those that I need more insight on.

Reference: https://www.electrical4u.com/buck-boost-converter/
I don't have quite a good grasp yet on the topic but I do know that buck converter causes a step down in the output voltage while boost converter causes a step up in the output voltage.
I would like to know how changing values in the inductor, capacitor or load can affect in particular other parameters such as output voltage and probably how they affect the circuit in general.
By the way, you guys can refer to this Stack Exchange link as it talks about changing load in a buck or boost converter and how it affects the output voltage. Why does voltage change with load in buck/boost converters?. You can use it when explaining if you think part of your answer might end up being a lengthy explanation of something that is there.
Why does voltage change with load in buck/boost converters?
I've also referred to that link because I have a separate question which asks "How does the duty cycle and input voltage in a buck or boost converter affect the circuit?" and I did refer to the formula relating input voltage, duty cycle and output voltage and mention how it only applies for continuous conduction mode. After that question comes the one mentioned in this topic which focuses on the inductance, capacitance and load instead.
Edit: Here is a more accurate basic buck topology.


texts: Not being able to enable PWM using the HAL TIM library on stm32f0

texts:
The goal is to use the PWM feature of stm32 HAL TIM libraries to light up 4 leds on pins 0, 1, 4 and 5

I have generated the following code using CubeMX:

void MX_TIM3_Init(void)
{
  TIM_ClockConfigTypeDef sClockSourceConfig;
  TIM_MasterConfigTypeDef sMasterConfig;
  TIM_OC_InitTypeDef sConfigOC;

  htim3.Instance = TIM3;
  htim3.Init.Prescaler = 32;
  htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim3.Init.Period = 1000;
  htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  HAL_TIM_Base_Init(&htim3);

  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
  HAL_TIM_ConfigClockSource(&htim3, &sClockSourceConfig);

  HAL_TIM_PWM_Init(&htim3);

  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  HAL_TIMEx_MasterConfigSynchronization(&htim3, &sMasterConfig);

  sConfigOC.OCMode = TIM_OCMODE_PWM1;
  sConfigOC.Pulse = 500;
  sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
  sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
  HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_1);

  HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_2);

  HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_3);

  HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_4);

  HAL_TIM_MspPostInit(&htim3);
}

This initiates the timer.

void HAL_TIM_MspPostInit(TIM_HandleTypeDef* htim)
{
  GPIO_InitTypeDef GPIO_InitStruct;
  if(htim->Instance==TIM3)
  {
  /* USER CODE BEGIN TIM3_MspPostInit 0 */

  /* USER CODE END TIM3_MspPostInit 0 */

    /**TIM3 GPIO Configuration
    PB0     ------> TIM3_CH3
    PB1     ------> TIM3_CH4
    PB4     ------> TIM3_CH1
    PB5     ------> TIM3_CH2
    */
    GPIO_InitStruct.Pin = GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_4|GPIO_PIN_5;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_LOW;
    GPIO_InitStruct.Alternate = GPIO_AF1_TIM3;
    HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

  /* USER CODE BEGIN TIM3_MspPostInit 1 */

  /* USER CODE END TIM3_MspPostInit 1 */
  }
}

This initiates the GPIO pins for PWM.

Also the clock is enabled in the HAL_TIM_Base_MspInit callback function using __TIM3_CLK_ENABLE().

In the main.c file I have added the following code after all initializations, to start the base timer and PWM:

HAL_TIM_Base_Start(&htim3);
HAL_TIM_PWM_Start(&htim3,TIM_CHANNEL_ALL);

Now after running this code on the stm32f070cb the LEDs do not light up at least slightly.

I have tried changing the compare values CCRx. Also the GPIO pins work since I can use HAL_GPIO_WritePin to turn on the LEDs.
Besides that I found out that the counter is actually running between 0 and 1000 using the __HAL_TIM_GetCounter macro. It just seems that the LEDs are not reacting to the compare values.

Did someone have a similar problem or have some hints to go from here?


texts: What happened to Depletion region when biasing is Off after applying reverse biasing?

texts:
I was studying Diodes and I came across the information that when the diode is reversed biased the depletion region is increased. Now the depletion region is composed of neutral atoms that are combined and some layer is formed that further halts the movements of electrons and holes.
When the diode is forward biased the depletion region is shrinked and when the diode is reversed biased the depletion region is widened as more neutral atoms are created near the layer. This is perfectly understandable why this phenomena happened. The next thing is the diode required some voltage in order for the electrons to cross the depletion region after biasing. This voltage is 0.7 volts or nearly 1 volts in case of silicon. When the depletion region is widened obviously more voltage is required by electrons to cross the depletion region.

So my question is that when the biasing is off (Electric source) what happened to the depletion region after reverse biasing which cause the depletion region to be widened, will it come back to the normal where it was initially and why and by which mechanism it will come back, or if it was not suppose to come back to the normal then it means that voltage required to cross the depletion region will be changed depending upon the thickness ?

Most electronics book (Which I studied) mentioned the phenomena of forward and reversed biased and mention their change on the deplition region but didnt mention that when the biasing is off after applying the reverse or forward biasing then what would happened.


texts:
So, i'm trying to communicate with a heat sensor using SPI with a chipkit pic uno32.

I connected Pin 10 (SS), Pin 11 (DIN), Pin 12 (DOUT), and Pin 13 (CLK) on the Uno32 board to the sensor

SS-Chip Select
DIN - Data Input
DOUT - Data Output
CLK - Clock

int i;
    IEC0CLR=0xFFFFFFFF; // disable all interrupts

SPI1CON=0; //desliga SPI

SPI1BUF=0; //limpa buffer

SPI1BRG=0x1; // use FPB/4 clock frequency

SPI1STATCLR=0x40; //limpa bit SPIROV

SPI1CONSET=0x0520; // 16 BITS | FALLING EDGE | Master Mode

SPI1CONSET=0x8000; //liga SPI

SPI1BUF=0x10; // transmit an A characte
while(SPI1STAT & BUSY)
{
    write_str("A receber\n\r");
}
printf("%d\n\r",SPI1BUF);

The printf and write_str function works and sends data trough serial port (UART).
So when i put something in the buffer its supposed to transmit that data and receive the data from the sensor, in this case the temperature (value with 10 bits). However i always get the value 0 (which corresponds to 0 degress celcius which is incorrect).

Need help,

Thanks


texts: common emitter amplifier output distortion

texts:
why the output of the Amplifier is distorted?

the input from the function generator is 1 Vp
the amplifier is baised at collector voltage of 4.5 V
the frequency of the input signal is 1 khz
the cutoff frequency of the input RC is 31.8 hz
gain is about 1.2

i should get ~1.2v distortionless output


texts:
From what I know so far (might be wrong), The ideal or  unity power factor means that all the energy is consumed by resistive components and are converted to heat, light, etc. In this case apparent power and real power are equal.

On the other hand, if reactive power exist in the system we have stored energy that is not used. That is why  power factor correction is used to get rid of the reactive power (stored power that just sit there and do nothing).The power factor correction introduces other storage unit so that they would provide current back and forth between the storage elements and hence less current is drawn from the power supply.

My question is if this statement that I conclude from the correction of the power factor is correct: "By correcting the power factor less energy is used in the circuit and hence less current is entering the circuit.This would result in  less power loss since current has decreased"

If this statement is not true, then what is the point of power correction?


texts: Is a buffer needed to measure the output of a power supply using an ADC?

texts:
I know from searching that it is good practice to buffer the input of an ADC input signal with say a unity gain Op-Amp, but the discussion is always based on the input being some sort of sensor that has low current/high output impedance and the buffer is used to match the sensor output with the load of the ADC.

Is a buffer still needed/recommended if the input to the ADC is a strong signal like the output of a system DC Power Supply running through a voltage divider to adjust the voltage down to a range the ADC can work with?

For example, my product has a 24VDC 3Amp switcher supply that powers the entire system, including the micro-controller. I want to to monitor the Power Supply voltage level by feeding it into the ADC of the micro. I will use a voltage divider to get the max voltage down to 3V but is it still a good idea to feed that voltage to op-amp to buffer it?

Thanks for any and all advice.

Thanks for everyone's feedback. The ADC will be part of either an STM32 M3 or NXP Coldfire microcontroller. Due to the voltage divider I will simply play it safe and buffer it.


texts: Voltage Controlled Butterworth Hi-Pass Filter using a Transconductance Op Amp?

texts:
In the Texas Instruments datasheets for the LM13700 Transconductance Op Amp (as well as the earlier National Semiconductor versions) there's been an application note showing a voltage-controlled 2 Pole Butterworth low pass filter (in the TI datasheet this is shown in Figure 34 on page 15):

I'm using that filter but would like a symmetrical high pass filter (likely using the same RC values as the low pass). I basically need a balanced pair of voltage-controlled low and high pass filters.

Does anyone know either of an existing schematic (in a book or online) or otherwise how I'd design an equivalent voltage-controlled 2-Pole Butterworth high pass filter? I've tried diagramming it and can't figure out, apart from the obvious bit of connecting the output of the first stage to the second, where the feedback is between stages. This is complicated by the fact that the high pass filter (Figure 33) uses the juncture between the output and buffer input (pins 5 and 7) as the source input:

I suppose the easiest way to approach this would be to ask: what changes would I make to the existing low-pass filter (Figure 34) to make it high-pass? This would seem straightforward were it not for my own limitations. [Oh, and apologies by way of explanation: I'm not an engineer but likewise not exactly new to analog circuitry, but I am to use of transconductance op amps.]

If it's any help, this is for audio range frequencies with a +-9VDC supply.

Thanks very much for any assistance.


texts:
I would like to know to know why UART errors occur, and when one should check for such errors. There is a post on here that asks about handling individual errors, such as overrun, parity, etc... I am clear on why data overrun happens, why parity error happens, but I would like to know what is the root cause. My question is more focused on why these errors could occur (physical reasons), and when one should do make error checking a factor for their application.

So far my program seems to work great (with no error checking), but I know that noise can mess things up. How could I simulate conditions that could cause the UART Rx/Tx ports to fail?


texts: HOMEWORK: Need assistance inputing Mesh Analysis complex equations into TI89

texts:
Good Afternoon,
I am having calculator difficulties in regards to inputing my mesh equations into my TI-89. The answer I am receiving is not the answer that was presented in the solution provided by my TA. I also double checked that my mode was in degrees.
I uploaded the original solution and problem. The second link is to an image of my matrix.
Thank you!
Edit: Working link to my matrix: https://imgur.com/5j0g3Ce


texts: Why do MOFET need so many contact windows?

texts:
I don't understand these sentences from Razavi's book, Design of CMOS Integrated Analog Circuit,

'the gate polysilicon and the source and drian terminals are typically tied to metal(aluminum) that serve as interconnects with low resistance and capacitance. To accomplish this, one more "contact window" must be opened in each reigon, filled with metal, and connected to the upper metal wires'.

Does this mean that one and more "contact window" could lead to low resistance and capacitance, if it is, how could it be?


texts: When I have series circuit with 3 light bubbles the voltage in second should be less than in first and the voltage in third should be less than in second. Conventional current flow is from positive to negative while electron flow is from negative to positive. Which light bulb will get the lowest voltage - the one closest to negative charge of battery or the one closest to positive charge of battery? (correct me if my reasoning is wrong)


texts: What are the extra lines on this farfield plot?

texts: This is a plot from CST microwave studios of the farfield beam pattern of an antenna. I'm having trouble understanding why the plot isn't single-valued (2nd red circle) and also why there are blue lines. Any help would be much appreciated


texts: how to apply frequency-dependent attenuation to a signal

texts:
Let's suppose a signal like this:

the frequency domain plot of such a signal is:

Now, What I intend to do is to apply a frequency-dependent correction to the signal.
For example, the attenuation rate at 40 MHz is 2.2dB while at 50 MHz it is 2.5 dB.
Is it alright if I apply the correction to the magnitude value in each desired frequency in the frequency domain and then use the inverse Fourier to achieve the modified time-domain plot of the signal?


texts: Interfacing barcode scanner with arduino using RS232

texts:
I want to connect a barcode scanner with Arduino. I used MAX232 to convert the levels. I have taken only 3 pins: 2(RX), 3(TX) and 5(GND) from the DB9 cable and given them to pins of MAX232 as shown in the figure:

This is the code written in Arduino:

#include <SoftwareSerial.h>
SoftwareSerial mySerial(6, 7); // RX, TX

void setup()
{
  Serial.begin(9600);
  pinMode(6,INPUT);
  pinMode(7,OUTPUT);
  mySerial.begin(9600);
}

void loop()
{
    if (mySerial.available())
    Serial.println(mySerial.read());
}

When I move the TX pin on DB9, I get readings like 255, 240, 189, etc., i.e. random numbers. However, when I scan the barcode, I am not getting any output.
I also checked the output of TX pins on an oscilloscope, which showed symmetric waves for a very short amount of time. Again, when the pin 12 of MAX232 (TTL output) was connected to the oscilloscope, no reading was observed.


texts: Result of constant current through DC motor under different loads

texts:
I've done some research on brushless DC motor and have a few questions what would happen when a constant current is sent to a DC motor.

From my understanding, the current is directly related to the torque that the motor supplies, while the voltage would relate to the RPM.  My question is, what would happen when you try to keep the current supplied constant, regardless of the load/rpm.

For example, let's say you have a weight attached to the shaft of the motor, like in this picture:

You set current to be sent to the motor so that the torque applied is 10 in-lbs without any load.   In this scenario, this current doesn't change.  You attach a weight to the end of the pulley.  What happens when the torque from the weight/load is 5, 10, and 15 in-lbs.

I assume, in the 5 in-lb scenario,  the motor pull the weight up, at 10 in-lbs the motor would stall, and at 15 in-lbs, the weight would drop and it would actually be acting as a generator.

Now, I'm obviously ignoring the voltage and back-emf in this scenario.  How would they play a role?  Without any voltage, there won't be any current running through it, so there's no torque applied.  But beyond that, would the voltage only affect the acceleration?

Sorry if this question has already been answered, but most of what I found related to a constant NET torque, not a constant applied torque from the generator.


texts: How to get the MSB into a logic gate which will check if a number is negative or not?

texts:
I need to create a logic gate which will find out whether a number is negative or not.

The input is 8 bits and the output is 1 bit, and if the input is 1 (i.e. negative number) then the output should also be 1, but if the input is 0, then the output should also be 0, so it kinda works like a NOT gate without the inverter.

I've read about the MSB and how it works and that I'd need to feed it in to the input but I'm not entirely sure how to write it. I'm going to be testing this on a HDL, so I'll need to write it a bit like:

Not(in=in[1], out=out[1];

and so on.

Any ideas?


texts:
I've found an article about memory distortion issues in audio analog amplifiers. Available for free here.

The author uses in the last configuration a CFP differential input with a cascode of FET controlled by the input and the feedback.

I want to use the same method on the Voltage Amplifier Stage (VAS), to provide constant power:

I used a CFP Vas with a cascoded MOSFET. Is this possibile? Is this good? Is the principle of memory distortion correct? Does what I'm doing make sense?


texts:
I'm doing up a Steadicam that takes power from a V mount battery and feeds it via a socket at the top to the camera and other devices and a socket at the bottom to the monitor and such.
  I've done all the work but have realised the the V mount puts out 14.5V and some of the kit wants 12V and could be a bit sensitive about the difference. I checked the battery and fully charged it puts out 15.5V and I'm draining it now to see if these is much difference when it's almost empty.
  So I need to open up the battery bracket I built and put something in there to regulate it to 12V. There's not too much room so I'm looking for something small, to be specific more flat than boxy.

So I've been a bit unclear, On a 12V regulated battery plate a 190Wh battery lasts about 3 hours when it's all rigged up.

As for the unregulated power out of my new plate it's at between 11-15.5V depending how full the battery is. Sorry for the confusion.

Any ideas or advice?


texts: Calculating the transresistance in a multistage voltage-shunt(shunt-shunt) feedback amplifier

texts:
I've been trying to analyze the following circuit using whatever books and resources I have to hand:

simulate this circuit – Schematic created using CircuitLab

I've identified the topology as a voltage-shunt feedback amplifier (is this correct?)  It looks as if the voltage is sampled at the output and the feedback current is subtracted (anti-phase) from the source, therefore voltage-shunt.

Any examples I've seen for this type of topology are either the collector feedback single stage amp or and classic inverting op-amp circuit.  But, I haven't come across any multi-stage examples on which to base my analysis.

Applying the usual rules (short Vo to find input, short Vi to find output) to find the circuit to calculate the open loop gain for this topology, I get the following:

simulate this circuit

Using AC analysis for each stage, I calculate the trans-resistance for stage 2 (Rm2) as 27k, given by:

Note: I've used certain sensible (I think) simplifications here.

$$Rm2 = \frac{Vo}{Ib2}=hFe\cdot R5=(100)(270)=27k$$

and the trans-resistance of stage 1 as:

$$Rm1=\frac{Vo1}{Is}=\frac{-Ic1\cdot RL}{Is}=\frac{-Ic1}{Ib1}\cdot\frac{Ib1}{Is}\cdot RL=hFe\cdot \frac{Ib1}{Is}\cdot RL = -73k\\\\
where RL = hFe\cdot R5 \parallel R1 = 27k \parallel 820 = 795\\\\
and Ib1 = \frac{Is\cdot Ri}{Ri + hFe\cdot re} where Ri=R2\parallel R3\parallel R5$$

I'm not sure I've gone about this the right way, but it seems that multiplying the two trans-resistance values is not the way to go (like you'd do for multi-stage voltage-series amps).

So, my question is: how do I proceed to get the open-loop trans-resistance in this (or any) multi-stage voltage-shunt configuration?

UPDATE: Thinking about it, I could use the same method as with a current-shunt feedback amplifier and express:

$$\frac{Vo}{Is}=\frac{Ib1}{Is}\cdot \frac{Ic1}{Ib1}\cdot \frac{Ib2}{Ic1}\cdot \frac{Vo}{Ib2}\\\\
=\frac{Ib1}{Is}\cdot hFe\cdot \frac{Ib2}{Ic1}\cdot \frac{Vo}{Ib2}
$$

but I'm just not sure.


texts: I'm looking at a datasheet for a digital circuit and it specifies that the typical input hysteresis is 100 mV. What does this mean exactly?


texts:
I've looked at articles detailing I2C level shifting and referencing the below figure I have a question.

If the gates of the FETs were driven by 2.5V and everything else remained the same, would the level shifting still work?

I would think a low from the 3.3V side would propagate but a low from the 5V would not get through.

At what low-side voltage or gate voltage would this circuit not work?

thanks


texts: Battery for reliable field sensor with low temperature conditions

texts:
I'm designing a frost alarm for farmers. The basic idea is that the farmer puts a sensor somewhere in his field. This sensor reports the temperature every 10 minutes to a base station with a wireless link. When a temperature near 0 degree Celsius is detected an alarm will sound and the farmer can save his crops from the frost.

This sensor needs to be very reliable and work at least 6 months without intervention. (So a low self discharge battery is required.) I'm thinking about using a low power AVR microcontroller and a HopeRF RFM12BP 500mW (max) wireless module.

What is the best battery (technology) for this sensor? Most batteries perform badly under low temperatures like -10 degrees celcius. My sensor should still work under such condition. I prefer a rechargeable battery, size and weight are not very important.

This is what I already found about battery performance at low temperatures:

NiMH: Very poor
NiCd: ??
VRLA (sealed lead-acid) ??
Li-ion: Poor
Li-Po: Better
LiFePO4: ??


texts:
Can someone please explain how the Arduino bootloader works? I'm not looking for a high level answer here, I've read the code and I get the gist of it. I've also read through this other post (I had even been one of the responders to it).

There's a bunch of protocol interaction that happens between the Arduino IDE and the bootloader code, ultimately resulting in a number of inline assembly instructions that self-program the flash with the program being transmitted over the serial interface.

What I'm not clear on is on line 270:

void (*app_start)(void) = 0x0000;

...which I recognize as the declaration, and initialization to NULL, of a function pointer. There are subsequent calls to app_start in places where the bootloader is intended to delegate to execution of the user-loaded code.

Surely, somehow app_start needs to get a non-NULL value at some point for this to all come together. I'm not seeing that in the bootloader code... is it magically linked by the program that gets loaded by the bootloader? I presume that main of the bootloader is the entry point into software after a reset of the chip.

Wrapped up in the 70 or so lines of assembly must be the secret decoder ring that tells the main program where app_start really is? Or perhaps it's some implicit knowlege being taken advantage of by the Arduino IDE? All I know is that if someone doesn't change app_start to point somewhere other than 0, the bootloader code would just spin on itself forever... so what's the trick?

On a separate note, would it be possible for the bootloader code to rely on interrupts or is that a no-no?

Edit

I'm interested in trying to port the bootloader to an Tiny AVR (specifically the ATTiny44A) that doesn't have separate memory space for boot loader code. As it becomes apparent to me that the bootloader code relies on certain fuse settings and chip support, I guess what I'm really interested in knowing is what does it take to port the bootloader to a chip that doesn't have those fuses and hardware support (but still has self-programming capability)?

I was thinking I could use the implementation of AVR307 to use the USI as a half-duplex UART (uses Timer0 interrupt, and pin-change interrupt). Can anyone offer guidance on how to go about writing/porting the bootloader code for a chip that doesn't have hardware support for bootloaders?

I presume I would put my bootloader code at the normal location for address main (e.g. 0x029e or wherever the compiler puts main). I would then make it so that 'address' in the bootloader code added an offset that put me just past the end of main, and have 'app_start' set to that address. Am I thinking about this correctly or am I totally missing something? Thanks!

EDIT 2

FWIW, I found a documented process for how to load Arduino sketches onto a ATTiny85, which is where I was originally going with this question... pretty neat I think


texts: Why do battery chargers work on even numbers of batteries?

texts:
I have some battery chargers for AA rechargeable batteries. They are differnt make and models by different vendors, but have the following in common:
Both have four charging slots, and both can only charge in pairs, i.e., they charge well if I put batteries in slots 1&2, or 3&4, or 1&2&3&4.

What is the technical reason behind this? Why can't these devices charge only one slot or other combinations? (Also: Could these cause problems when I add a full or semi-full batterie just in order to turn a singleton into a pair and charge a single empty battery?)


texts: LM317 adjustable constant current source - Why is the voltage between Output and Adj pins is not always 1.25V?

texts:
I am trying to create an adjustable constant current circuit using LM317 to drive LEDs of different colors.

More specifically, I want the brightness of the LEDs to be the same, therefore, the current flowing through them will be different for different colors. I searched online and found this circuit, which outputs a current between 125-400 mA.

I want the current to be between 1-3 mA, so I played around with the resistance values of R1, R2 and R3 (potentiometer.) When I tried certain resistance values (R1 = 10k, R2 = 2k and R3 = 50k), I found that the voltage between the output and adjustment pins is not always 1.25 V. Why is this so? Are there limits to which resistance values we have to use in order to maintain a potential difference of 1.25 V across the output and adjustment pins?

(P.S. I am supplying 9V into the LM317.)


texts:
I have the radiation pattern for a dipole antenna with working frequency of 11 GHz, it looks like figure 1. I wanted to create an array antenna consisting of 2 elements with that same individual radiation pattern and a spacing of 0.75*wavelength, it should look something like figure 2.
My doubt is, how do I create the antenna pattern for the array, with the single element radiation pattern? In other words, how do I create figure 2 using figure 1?

Figure 1

Figure 2


texts:
This is probably a very easy question, but I've been trying for several weeks now to create a simple circuit that "fades in" some LEDs using only discrete components like resistors, capacitors, inductors, (photo) diodes, transistors, and a voltage source.

  Using only discrete parts (no ICs), how do I "fade in" a few LEDs over the course of a second or two?

I've managed to create the opposite, the "fade away":

+Volts connected to "RC" and then to "PL" and then to ground in series
RC is a resistor and capacitor in parallel
PL is roughly some leds in parallel: PL1 and PL2 in parallel
PL1 is a LED and resistor in series
PL2 is three LEDs and resistor, all in series

When powered up (at +6V with the RC using 1K ohm and 2200uF) all LEDs immediately light (no fade in at all), but over 2 seconds the triple LED (PL2) fades to black.

I can of course make this using an Arduino and the PWM output pins to make intricate fade in and fade out patterns, but the circuit is to demonstrate using a simple transistor to switch a system on, and if I'm using a microcontroller to drive that system, I might as well have the transistor trigger my laptop to play a youtube video.


texts: Calculating cutoff frequency of RCL circuit

texts:
Given is this circuit:

I know that:

$$G(j\omega)=\frac{\frac{1}{j\omega C}}{j\omega L+\frac{1}{j\omega C}+R}$$

But how do I calculate from this my cutoff frequency?


texts: A robust way to supply power to a solenoid

texts:
Solenoids typically heat up very quickly and it seems a few seconds of power supply is already adequate. Does anyone know of a robust/established way for supplying just a few seconds of power to a 12V/1A solenoid? How about cap discharge?

Thanks

EDIT 1 The solenoid pushes and pulls a lock for my rabbit house, so continuous operation isn't needed. In fact, my solenoid needs a fair bit of cooling time.

EDIT 2 My current plan is to drive it with 8051 and a transistor, but I'm open to alternatives. I could get the 8051 to give the pulses, but I fear that my code is buggy and frying my rabbits as a result. So I was hoping to come up with a relatively fail-safe method.

The solenoid is spring loaded, so that the pin retracts when the solenoid is engaged (spring is compressed) and releases when it's not (spring is released). With this motion, I'm planning to get it to unblock and block the gate (thus, a lock).

The rabbits will be locked up at night.


texts: I am wondering if I have the right idea. I need to connect my computer to my servers serial port for some debugging, I have no other computers that have serial ports but I have FTDI serial boards for programming some arduinos. If I connect the pins of the FTDI board to a DB-9 connector and Cross the Tx<->Rx will that work?


texts: How to set the sheet size in Altium Designer?

texts:
A few days ago I started to learn Altium Designer 17 and immediately stumbled upon some strange behavior. I created my first component and decided to see how it will look on paper. So I added this component to a schematic sheet, set the sheet size to A4 (look at the screenshot below), tried to print it, and... got not what I expected.

I began to look for the causes and noticed that the sheet on my screen has the wrong proportions! Approximately 0.66 instead of 0.707 for A4. When I ticked "Use Custom Style" and set all the sizes manually, the problem was solved. Okay, that's good, but why the standard style called A4 doesn't work? I tried to do the same thing in Altium 18 and got the same result.

It is interesting that in the "Tools->Schematic Preferences" dialog you can set the default sheet size. If you set this size to A4, the parameter called "Drawing Area" becomes equal to 292x193mm, which gives us this weird 0.66 ratio. So... This is not a bug. But what is it?

To make it more clear I made a screenshot. Here is my schematic sheet. In the document settings, the size of the sheet is set to A4 (see the first picture in my question). According to the standard, A4 has 0.707 height/width ratio, but neither A/B nor D/C equal to 0.707!


texts: Simulation of voltage sensitivity of ideal detector diode circuit

texts:
Application note 969 derives the voltage sensitivity at zero bias of a detector diode:
\$
\gamma = \frac{V_o}{P_{\rm in}} = \frac{0.52}{I_s(1+\omega^2 C_{j0}^2 R_S R_V)} \cdot \frac{R_L}{R_V+R_L},
\$
where \$\omega\$ is the input frequency in rad, \$C_{j0}\$ the junction capacitance, \$R_V=\frac{nV_{th}}{I_s}=\frac{0.028}{I_s}\$ the nonlinear junction resistance and \$R_L\$ the load.
Their argument is made with small signal circuit approximations.
However, I want to "see" this by using an actual .diode element and sweeping over multiple Is values as in 1 (for example, via tran simulation).
I use this simple LTspice simulation which sweeps over the same range of Is as in 1:

As can be seen, I measure the output voltage and input power into the diode and then plot gamma1=Vout/Pin. gamma0 is the formula from above 1. If I set \$R_L=\infty\$ and \$C_{j0}=0\$, I get great matching results beween gamma0=0.52/Is and gamma1:

Note that I have to add some load to the output; I add a capacitor (although not explicitely described in 1). The caveat is I need to wait with until the signal has settled.
However, once I set \$C_{j0}\neq 0\$ or \$R_L\$, I no longer get a match. I tried various ranges of \$C_{j0}, R_L, C_L\$ and ensure the output voltage settles. For example, for \$C_{j0}=0.1\rm{pF}\$, I get:

What am I doing wrong?


texts: Voltage between two terminals of an open circuit which's connected in series with a current source

texts:
simulate this circuit – Schematic created using CircuitLab

What will be the voltage between nodes A & B?

My guess is that the voltage between nodes A & B should be increasing forever as the current source,I will keep on pumping charges to node A & due to increasing charge voltage will keep on rising.

Am I right?If not why?

Will the answer remain same if there's a voltage source at the terminal of current source,other than A?

Thanks for reading a question as silly as this.

If someone can suggest a source(book,site etc) where more such questions may be found,that would be great.


texts: How can a used alkaline cell rate at 1.9 volts?

texts:
Today I replaced the battery of four alkaline AAA cells in an LED bicycle lamp, which was connected in two parallel series of two cells**. The four old cells were installed new from the same pack and (unsurprisingly) look identical. The brand is Kodak Xtralife, and they are labelled as alkaline AAA LR03 1.5V. Their expiry date is marked as 09-2020.

I checked the voltage of the old cells: three measured at close to 1.32 V; but the fourth one was over 1.9 (sic) V. I tested the cells repeatedly, using three different makes of electronic multimeter, along with a new alkaline cell for comparison, which measured at 1.560, 1.570, and 1.576 volts on the three meters—absolutely normal figures as I would have expected from numerous such measurements in the past. The three meters were self-consistent in repeated measurements, with the low-reading meter reporting about 11 mV below the middle-reading meter, which in turn read below the high-reading meter, although in the latter case the differences between the two meters changed according to whether the measured voltage was 1.3 or 1.6 volts: respectively 2 and 6 millivolts.

While the three meters all reported initially above 1.9 volts for the fourth cell, I am finding that, with repeated measurements, the voltage is dropping on this cell, and it is now 1.879, 1.893, and 1.898 volts according to them.

New alkaline cells always test at about 1.57 V, the voltage declining with use. So how can a used cell test at 1.9 volts?

**This turned out to be wrong: the cells were actually in a single series of four.


texts: Charging a QC 3.0 USB-C Thunderbolt specced laptop via generic 15V charger

texts:
I have a USB-C PD & QC3.0 device. It takes 20V @ 2.25A (45W), or 15V@3A to charge.

I also have a 15V 5A portable charger with a female 5.5mm x 2.5mm output port. I plan to connect the 5.5mm x 2.5mm female output port to the USB-C device via a 5.5mm x 2.5mm-to-USB-C-adapter.

I do not need the fast charge modes. I just want to know : will it charge my device? Will it break my device?

p/s (My portable charger also has other output modes - 12V, 9V, 19V & 5V, I've only used the 5V all this time, curious to try other modes)


texts: What are these "X"s / crosses on this schematic's wiring? Traces attached to the metal housing (ground)?

texts: Below is a section of the schematic for the RF modulator of a Nintendo NES-001 system. I am curious what these Xs are that I've boxed in red below. Looking at my own NES-001 and matching locations, I think these points are where the board's ground connection is soldered to the grounded metal housing. I've been unable to find anything regarding this specific symbol.


texts: Frequency-To-Voltage Convertor With LM2917

texts:
I'm trying to make a frequency-to-voltage converter by using LM2917.

Its datasheet is very old and it doesn't explain function of the IC well. It just gives several example circuits and a formula for the output voltage. I want to learn working principle and internal circuit of the IC, and function of externally connected components (especially C41).

An example circuit from the datasheet.

I understand that, the input opamp works as a comparator and converts the sinusoidal signal into digital pulses. The charge pump is charging a capacitor (which one?) at each pulse, so the output voltage level becomes somehow related to the pulse count in unit time. But how does this charge pump do this? All the capacitors and resistors are connected to ground; I'm very confused at this step. What is the function of the second opamp? It is drawn to be a comparator rather than a buffer. This is confusing too.

(Vcc = 12V)

I need a circuit which generates 1mV voltage per 1Hz frequency. I created a custom library for this IC and set up my own circuit as seen in the schematics above. How do I choose value of C41 (I put a random one for now)?


texts: Wiring illuminated momentary switch to breadboard

texts:
Software engineer fearlessly venturing into the deep, terrifying, murky waters of electronics here. And hoping everyone can take pitty on me (and be gentle) as I ask this simple question...

I'm looking to connect this momentary switch to a solderless breadboard but its datasheet seems to be a datasheet for a generic set of devices in the same family of switches that the manufacturer makes.

I'm just looking to understand what its wiring would look like. I have to assume (based on my heavily limited knowledge of electronics) that there are pins for: output signal (when the switch is pressed/closed), ground/GND and (because its illuminated) its internal LED...or would pressing the switch also trigger the internal LED to light up?

I guess my question is: is there information in its datasheet, or on the DigiKey page, that would tell me how to wire it up on a breadboard? Or is the datasheet junk? Or am I supposed to just have working knowledge with switches/electronics to begin with and the wiring of this device would be obvious to most EE folks? Thanks in advance!


texts: Can this double-pole double-throw switch be simplified for controlling a motor (skylight)

texts:
I'm considering retrofitting skylight motors but would like to know if I can use standard home switches to control it. I have not found examples of up, down and open switches (is this 3 pole, normally open?). I imagine this should be similar for blinds or any motor that steps in two directions (but not just fully open or fully closed like a garage door).

The skylight manual contains this diagram, first below.

The second I simplified because I don't understand the need for a double-pole, double throw where the Neutral disconnects when untouched. Any ideas why they would want that?

Finally the third diagram shows my idea to use two momentary switches which I believe should work. However would anyone be able to speculate if the motor is likely to have protection against both open and closed being pressed simultaneously? Am I overlooking anything else?

Update
The winning solution is: https://electronics.stackexchange.com/a/340685/169328

The local supplier of one brand, Topp, that operates at mains voltage supplied the following diagram with matches second circuit diagram 2(b).

This uses two common momentary switches. Note how 2 feeds into C of the second switch.


texts: Would having no power supply but a large input signal damage the amplifier?

texts: I am now learning about the power sequence of the circuit. And wonder that as every amplifier has its own limited input voltage (for example: ADA4004's input limit is V− < VIN < V+), would the amplifier be damaged if no power supply but a large signal (maybe +-2V) injected into the input pin of the amplifier?


texts: How to get a flat band frequency response with an inductive input

texts:
I have a primary inductor L1 connected to a voltage source with frequencies varying from 0.5MHz to 15MHz. This primary inductor induces a voltage across a secondary inductor via coupling and I want to investigate the response generated in L2.

So I am trying to amplify a voltage from an inductor using an op amp in non-inverting configuration (image1). Upon doing an AC sweep I find that there is resonant frequency peaking at 3.5MHz which is presumably due to L2 forming an LC tank with the input capacitance(2pf) of the LT1886 amp (image1).

Now this is a problem because I want a reasonably flat band frequency response from 0.5MHz to 15MHz, so I was wondering how can I achieve such a thing if possible?

Here's a few things I've tried:

Place a reasonably large resistor R3 in the non inverting input to decrease the quality factor of the LC tank which should smooth out the frequency response (image2). However looking at the frequency response (image2) the roll off after 3.5MHz is still unacceptable, because I want a flat band response upto 15MHz.
Move the resonant frequency further away by decreasing L2 and then adjusting R3 accordingly (image3). This worked out quite well however I'm afraid that if the inductance L2 is too low the coupling will be insignificant and so the final amplified voltage is dominated by the amplifier's noise due to low signal to noise ratio.

I was also wondering if looking into current sensing would be a better option instead of directly sensing the inductor's voltage?

Image 1:

Image 2:

Image 3:


texts:
I want to build a water sensor that disconnects the motor when:
1. tank is full
2. water in input pipe is missing.

I came up with the following schematics (haven't practiced much electronics in last 10 years :))

simulate this circuit – Schematic created using CircuitLab

Sensors
The sensors are just 2 wires (R1, R2).

R1 (priming water sensor) is the resistance of input water (let's say 2K when water present and 1M when water missing). This makes sure the motor is not running without water.
R2 (tank full sensor) is the resistance of second water sensor.

Seems to work but I see a residual current (few mA) in the relay. The relay makes contact at 15mA, but I think firm contact is at 25mA.

I need to know if the relay might oscillate. Do I need some kind of digital trigger to make sure the relay is either on or off, but not in the middle?


texts: HUGE capacitor recommended in datasheet for Audio Amp

texts:
I'm using the TPA3111 audio amplifier in a circuit of mine and I'm working on adding the appropriate capacitors.  However, on page 18/19 of the datasheet TI recommends to use a 220mF capacitor on the power line along with a 220uF capacitor on each of the PVcc pins.  Is this entirely necessary?  If you take a look at the evaluation board TI offers for this chip they don't do any of that.  The same goes for the application case in the datasheet.

I'm already using quite a few capacitors according to the sample application and eval board.  The largest so far are 100uF electrolytics and then there are bunch of smaller ceramic caps.  Any idea on what dangers I might have if I do not include the additional 220mF or 220uF caps?

Thanks.


texts:
What is the difference between power ground and digital ground ?
What I understand is that the pgnd is the path through which the supply current discharges. Now the DGND, is the ground reference to the digital signals. How are they eventually connected ? Via a star connection ?

Another thing. If INA MCU we have 4 gnd pins which or rather how many will act as a pgnd and how many is dgnd ? Is there some logic in this ?

For eg - a signal from a gpio in an MCU will have a small current. This will travel via the gpio track into the other end and then go into the ground via ,say a and pin of that chip. So, which gnd pin will it take to discharge into the gnd plane ?
If ,say that other ic is an ic with just 1 gnd pin, how can it be classed ? So, pgnd and dgnd are quite loosely used and can be interchanged. In fact many chips have just 1 ground pin. So that pin is a power ground or a digital ground ? The way I see it, it serves as both. So this is a disadvantage as well. Because any noise on the supply rail can cause a ground imbalance. Likewise with digital part can dump a lot of noise on ground.


texts: What is maximum and minimum current through zener diode?

texts:
For a simple electronic voltage regulator using Zener diode, I use the following circuit.

For deciding Rs and RL, I need to know Izmax and Izmin of the zener diode 1N4736A used.
From this data sheet,

There are different current specifications available.
Maximum working current is given as 133mA. Again test current at working voltage is 37 mA. Somewhere, I found if zener works continuously at maximum working current, it will get damaged.
Also, somewhere minimum zener current is taken as 10% of maximum zener current whereas somewhere it is taken as the knee current (1mA) at which zener impedance is tested.
Which is the correct choice?


texts:
Well I'm struggling today, maybe I'm putting too much thought into this.  I'm trying to design the proper virtual gnd circuit for my opamp filter.   In real life my output will be a DAC with a current source into a 75 Ohm resistor.  The resulting voltage will always be positive since the current source is always positive.

So anyway I wanted to do an AC simulation in spice to make sure my changes to make this filter a single supply would work.   I don't quite understand why the simulation only matches the dual supply one if I put a 2Vdc offset on the AC source, 1Vdc offset results in much more attenuation at high frequencies.

The other thing I struggle with is I don't even know if this is the right way to model my source.  I feel like putting this strong DC offset in the AC source is throwing off my understanding of the virtual gnd circuit.

I've been trying different things and went back read about how AC simulations work, but still feeling frustrated by not understanding everything here.

Does anyone have any insight on why it only works at 2V offest, and if there is a better way to model my input?

The opamp I'm using is the Analog devices AD8051


texts: Experimenting interference effects for different measurement systems

texts:
This is about for low level signals interference/noise being observed with single ended data acquisition inputs but not with diff inputs. Basically there are three data acquisition boards, where one of them is a single-ended USB board, the other one is a single-ended earth grounded PCI board(can be set for diff ended as well) and the third one is diff-ended USB board. All are monitored by a desktop PC. Sampling rate is set to 1kHz for all. And all boards have the same resolution.

When I couple a source to inputs of these boards normally if there is no interference and noise I don't get issues for DC signals like 5V DC.

But sometimes I observe noise issues with single ended PCI board so I wanted to investigate about these empirically.But for this I needed a source with interference. Luckily I guess I found one. A function generator signal is read differently by the boards depending on they are single or diff ended.

I use this function generator as source for input signals to the data-acquisition boards. I set it to 10mV pk-pk 3Hz sinusoidal with no offset. So a good measurement should measure a similar signal which should resemble a 10mV pk-pk 3Hz sinusoidal. I use both STP and BNC coaxial cables. In this example I will use BNC coaxial cables.

First I use the function generator with 3-prong power cord. The function generator's output signal ground is connected to the mains earth through the power cord just like in a scope.

So first I use it with 3-prong power cord. Then I measure with the PCI single-ended earth grounded board and here is what it measures:

Above you can see the offset error and distortion in the signal.

And now I set up the same measurement with the single-ended USB board. Notice its ground is not earthed. And here I get the same problem:

There is offset error with significant distortion.

I noticed this distortion gets bigger with the cable length.

And finally here is the result from the diff-ended board's measurement:

Above there is almost no offset error and the noise does not distort the signal much. Looks like random noise. I also get similar measurement if I use the PCI board as diff ended input config.

And after all these I concluded diff-ended inputs are more immune to noise.

But then I used two-prong power cord for the function generator and the single-ended boards started to measure very accurate even a bit better than the diff-ended.

My questions are:

1-) I use cables around 15 meters up tp 50  meters. And seems to me like if there is no interference single ended is great. But when there is noise the dif-ended is better. In my case what could be the reason that using three-prong power cord for the function generator causes tis interference?

2-) How does this noise appears as offset and distortion in single-ended and does not appear at the diff.ended daq board?

3-) I want to show it to people to convince to use diff.ended board for better measurements. I was looking for long time a noisy interference scenario to test two systems single and diff ended but I failed to create interference. Can my setup be used to demonstrate the difference of these two systems(single vs diff ended)?

EDIT:

As I mentioned if I use 2-prong power cord(i.e no interference), I obtain the single-ended(blue) data even better than the diff-ended(red) case as below:


texts:
I have an Xmega chip I've been using for a year and had no problems with the PDI interface programming it with the Atmel-ICE debugger/programmer. The problem is I accidentally connected the cable to the "SAM" port instead of the "AVR" Port on the ICE. Now Atmel studio will not program the chip. I keep getting:

PDI enable failed. Debugger command Activate physical failed.
Unable to enter programming mode. Verify device selection, interface settings, target power, security bit, and connections to the target device.

Also, the AVR resets, so I think it is not seeing the PDI clock signal and taking the PDI as a standard reset now...

Why would Atmel make the SAM and AVR ports the same connector?? Could this have really blew out the PDI lines of my chip?

By the way, the chip still works, it is running the old code just fine, I just can't program it now.


texts: Automating simulation in cadence virtuso

texts:
I want to find out delay of a 16 bit adder designed in cadence virtuso icfb tool for a large number of input values and Vdd. I know how to simulate the design with a given input and find delays using delay function in waveform calculator. How can I do this analysis for a large number of inputs, say 1000?

Thanks in advance!!


texts: Do photons come out when electrons and holes recombine inside a forward biased diode?

texts:
When electrons fall to a lower level orbital they emit light/radiation at a particular frequency.

Is that the case for recombination?

My question came from this speech at the following part: https://youtu.be/Cdr89n_nf9Y?t=1639 which Im not sure I understood correct.

The lecturer gentleman in the video invented the point-contact transistor in 1947.


texts: What is the difference between LPDDR2-S2 vs S4?

texts:
Looking at page 18 of the JEDEC spec on LPDDR2

  LPDDR2-S2 also uses a double data rate architecture on the DQ pins to achieve high speed operation. The double data rate architecture is essentially a 2n prefetch architecture with an interface designed to transfer two data bits per DQ every clock cycle at the I/O pins. A single read or write access for the LPDDR2-S2 effectively consists of a single 2n-bit wide, one clock cycle data transfer at the internal SDRAM core and two corresponding n-bit wide, one-half- clock-cycle data transfers at the I/O pins.

  LPDDR2-S4 and LPDDR2-N also use a double data rate architecture on the
  DQ pins to achieve high speed operation. The double data rate
  architecture is essentially a 4n prefetch architecture with an
  interface designed to transfer two data bits per DQ every clock cycle
  at the I/O pins. A single read or write access for the LPDDR2-S4 and
  LPDDR2-N effectively consists of a single 4n-bit wide, one clock
  cycle data transfer at the internal SDRAM/NVM core and four
  corresponding n-bit wide, one-half-clock-cycle data transfers at the
  I/O pins.

I am trying to figure out the difference between S2 and S4. Does this mean with a 266MHz clock from the processor, S2 is only capable of transferring 533Mbps while S4 can transfer 1066Mbps at that same frequency?

EDIT:
I also found this on the wiki page about prefetch buffers.

    The prefetch buffer depth can also be thought of as the ratio between the core memory frequency and the IO frequency. In an 8n
    prefetch architecture (such as DDR3), the IOs will operate 8 times
    faster than the memory core (each memory access results in a burst of
    8 datawords on the IOs). Thus a 200 MHz memory core is combined with
    IOs that each operate eight times faster (1600 megabits per second).
    If the memory has 16 IOs, the total read bandwidth would be 200 MHz x
    8 datawords/access x 16 IOs = 25.6 gigabits per second (Gbit/s), or
    3.2 gigabytes per second (GB/s). Modules with multiple DRAM chips can provide correspondingly higher bandwidth.

  Each generation of SDRAM has a different prefetch buffer size:

  DDR SDRAM's prefetch buffer size is 2n (two datawords per memory
  access) DDR2 SDRAM's prefetch buffer size is 4n (four datawords per
  memory access)


texts: Frequency Modulation with same carrier and message signal of same frequency but different amplitude

texts: How is frequency deviation calculated for a FM wave? Suppose we have a same carrier and a sinusoidal message signal of frequency 5Hz and maximum amplitude of 5V and another sinusoidal message signal of frequency 5Hz but amplitude of 10V will frequency deviation be different or same in both case?


texts: What is the 14 pin IC that is associated with an ATMEL 312 24C02N IC?

texts: Does anyone know what the 14 pin IC in this picture is? This circuit drives an RGB LED strip with 24 LEDs. The 14 pin IC does not have anything printed on the case. I understand that not having the part number printed on the case makes it difficult to know what specific IC is used in this circuit, for this very reason, I am asking electronic engineers for help. Thank you for taking the time to help me with my question.


texts:
I am looking at many electronic forums and people always come up with different answers, so I would like to settle this question once and for all.

Does a twisted pair cable radiate more EM radiation than non-twisted pair? In the sense of generating EMI interference for nearby equipment and/or radiating the signal from inside the cable to a larger distance.

Let's just ignore shielding for a moment and focus on the twisted pair/non-twisted pair types, which setup radiates less EM radiation?

We know that the twisted pair cable shields the signal from outside interference, but does it shield other cables from its own generated interference? Is it vice versa?


texts: As we know ,in MOS differential amplifiers we have Rd mismatch and gm mismatch.These mismatches have effects on the differential amplifier.Which of the effects of these mismatches is more dominant in your opinion ?And why


texts: I don't know if this is the best place, but it seems the best out of the exchanges. How do you attach a plastic (or metal) gear to the little pole/nub that sticks out of a dc hobby motor? I have come up with 3 ideas: gluing, it doesn't seem like it would hold well; soldering, maybe but what about plastic gears; and making the hole on the gear slightly smaller so there is enough friction to hold it well, the most likely solution. Has anyone tried these or any other?


texts:
I need to build a VGA cable (assemble connectors to wire).
I need a male-male cable.
Is its wiring straight or cross? (should i connect 1-1,2-2,... or something else)

Thanks


texts: What is the difference between these resistors?

texts:
Take a look at these two different resistors:

 Fig.1 source

 Fig.2 source

The first one looks "normal" to me (the way resistors I've always bought in the past look..), but the second looks kind of odd. Both of these pictures are of 5% carbon film resistors.

What's the difference between them?


texts: How to program ATmega with fuses set to 32.768kHz clock?

texts:
I've been programming my ATmega328P's using USBasp programmer for a while. For my new project, I wanted to use 32.768kHz oscillator as an external clock, so I programmed the ATmega to appropriate fuses. Unfortunately, from this point on, I cannot communicate with the chip at all - avrdude tells me that target doesn't answer (rc=-1 error). After some research, I found some tips telling me to connect the oscillator (and capacitors) to chip's XTAL inputs, and then program the chip. I tried that, to no avail. Note that I also used avrdude's -B 2000 switch, that slows down the programming as much as possible - to 500Hz, so programming speed shouldn't be an issue.

In a desperate attempt to rescue chip, I tried Arduino as ISP, but the results were pretty much the same.

Questions:

How to rescue this particular ATmega? Is high voltage programmer the only way out of this? I don't have one, so other options are welcome.
For the future: how should I program slow clock fuses so that I avoid this problem? It doesn't make sense for me - if programmer doesn't work with such fuses, why is there such a fuse setting in the first place?


texts: Can 3.3V circuit power be used to power garage door opener that uses 3V CR2032 coin battery?

texts: I have a garage door opener normally powered by 3V CR2032 coin cell.  I want to power it from the 3.3V power rail of a circuit.  Can I use the 3.3V directly?  Will it damage the garage door opener?  Or must I bring it down to 3V with a resistor first?


texts:
What is the standard maximum copper thickness for minimum pitch size of a SMD component in a PCB?
For example, what will be the maximum copper thickness for a pitch of 0.65 mm? Or is there any standardized table for such comparison.


texts: How does the charging curve of a deep-cycle lead-acid battery change as it degrades?

texts:
I am designing a circuit inside a UPS that periodically tests how long the battery can power the load. It does this by breifly disconnecting the power from the UPS and extrapolating from the measured voltage over the battery.

How does the discharge curve change after the battery has begun to degrade and loose capacity?
Does the curve simply scale down linearly?


texts: When to use a Hall probe and when a fluxgate magnetometer to measure magnetic fields?

texts:
I am familiar with how the two methods work, but what applications are more suitable for one rather than the other?

I have seen this question but I don't think it covers my point.


texts: Reduce current in momentary latch toggle / source capacitors

texts:
I started on this thread:
Make a momentary switch control a toggle Tried all my own research before bothering the community with a question; hope I've done my due diligence.

I found this is one of the answers:

Which is from here

I have 4011s on hand so this is a great solution.

I built it in a simulator on Tinkercad

My parts list:
1   5V Regulator [LM7805],
1   9V Battery,
1   Quad NAND gate [74HC00] (I'll sub a 4011 in the final build),
2   100 kohm Resistor,
1   Red LED,
1   470 ohm Resistor [LED to ground],
1   Pushbutton,
1   1 uF Capacitor [left],
1   0.01 uF Capacitor [right],

Here is the diagram for the 74HC00:

It's a 5v circuit unless the capacitors are changing that so the chip should take it.

The problem that I'm having is that the circled connection is back-feeding 57.3mA when the pin is only rated for 25mA. This also puts the total current throughput at 63.3mA when the max is 50mA. On the diagram this connection is the output of the first [left] nand.

How can I correct my current problem? Sorry for the pun.

Can these be electrolytic capacitors? Because I'm having trouble finding ceramics in 1 uf and 0.01 uf.

Thanks a bunch