texts: EMI Filter - DC DC Converter No Differential Mode Filter Outlined

texts:
I am currently looking at installing a DC-DC Converter. https://www.xppower.com/Portals/0/pdfs/SF_QSB300.pdf

The datasheet outlines a recommended EMI filter as so:

My question is as the datasheet clearly outlines a common mode choke/filter, is it assuming I understand that the filter is not complete? I have heard to this being done in datasheets before, and also at the top of the second page in the section on notes it states (after asterisk) "Output Ripple and Noise measured with 10 µF tantalum and 1 µF ceramic capacitor across output". In which case should the final filter design look something more like this (ignore fuse and MOV as obvious)?

2nd image taken from https://www.mouser.com/datasheet/2/670/pybe30-din-1525731.pdf

If so why in this second image are the capacitors connected to the output lines as opposed to the chassis of the converter (CY1 and CY2)? Thank you for your time.


texts: 4-position touch dimmer - waveforms unexpected, but functional. need suggestions for soft switching

texts:
I have a 4-position touch dimmer that is fed with 120VAC line voltage and outputs one of four 120VAC waveforms.  The output waveform is input to an electronic transformer labeled to permit "dimmed input."  The electronic transformer outputs 12VAC that powers several 20-watt halogen lights.  There is a small wire on the 4-position dimmer that serves as the contact point for dimming.  These are commercial grade components and the set up functions without issue.

What is my problem, then?  I am interested in soft-switching these lights with some sort of microcontroller and it's unclear how I would use the single-wire capacitive lead emerging from the touch dimmer with a microcontroller when there is no common ground connection.  I may be making more of a project of this than is necessary, but I am sufficiently confused. I looked at other similar Stack Exchange posts, but most are starting de novo.

More interestingly, I am very intrigued by the three dimmed waveforms that are output from the touch dimmer.  I had expected a little leakage in the "off" position (got that), but a triac-y looking waveform for the middle two waveforms and a mostly sinusoidal waveform for the "full on" final position.

The waveforms surprised me, most notably that the max voltage of the third position, 124V, is higher than the voltage of the forth, "full on", position 104V (also the V value of position 1).  Visually, I can see a more area under the curve in the forth position, but I don't understand the lower voltage.

Input waveform

position 1 -- "off position"

position 2

position 3

position 4 -- "max position"

Second set of pics.


texts: FIR filter output result Interpretation While input is taken from ADC161S626: 16 bit

texts:
I have implemented a 20 order FIR Low pass filter, 1000 HZ cutoff frequency on Sparten - 6 FPGA. First I calculate the coefficients in Matlab, Then I directly put them in vhdl code. Here are my coefficients.
H(0) <= to_signed(26,16); --10000HZ cutoff
H(1) <= to_signed(67,16);
H(2) <= to_signed(169,16);
H(3) <= to_signed(369,16);
H(4) <= to_signed(686,16);
H(5) <= to_signed(1111,16);
H(6) <= to_signed(1606,16);
H(7) <= to_signed(2108,16);
H(8) <= to_signed(2542,16);
H(9) <= to_signed(2836,16);
H(10) <= to_signed(2940,16);
H(11) <= to_signed(2836,16);
H(12) <= to_signed(2542,16);
H(13) <= to_signed(2108,16);
H(14) <= to_signed(1606,16);
H(15) <= to_signed(1111,16);
H(16) <= to_signed(686,16);
H(17) <= to_signed(369,16);
H(18) <= to_signed(169,16);
H(19) <= to_signed(67,16);
H(20) <= to_signed(26,16);

Now Actually I am taking an torque feedback Input from some sensor, The torque is converted in voltage. The voltage is digitize into 16 bit format.The filtered value, output of the filter is in 32 bit format.
Here is the snapshot of Teraterm. How do I convert the these values to voltages ? enter image description here

Thanks.
Edited:
On Page number 16 of this document they have given the conversions:
Now They have discussed about +IN, -IN, Vref. I would like to give my voltages here which I can measure on the adc pins using a multimeter:

Now ADC datasheet part:

Now the Digitized displayed values:

All of the above three image are recent. so How to relate the voltages at pins and the digitized value of voltage on the MISO pin, which I displayed on real term.
finally how to understand that what value of filter output represent what voltage ?
What is the effect of applying FIR filter here ?
Did it do something good or not ?..
In matlab simulations It definitely does some good & removes the peaks, but I am not able to understand in the implementation.
Thanks
please someone.


texts: Partially Collapse Telescoping Antenna to Change Effective Length

texts:
I recently purchased a cheap RTL-SDR kit to experiment with SDRs and different frequency bands. This kit came with 23cm and 100cm telescoping antennas. I now wish to use the 100cm antenna to pick up NOAA APT signals at 137 MHz. Many sites with instructions for a V-Dipole antenna for this purpose indicate that a 53cm half-wave antenna works well.

Is there something special about telescoping antennas such that they only work when fully extended, or can I partially retract the 100cm antennas to 53cm to get the proper length for NOAA APT reception?

[I also posted this question on Amateur Radio Stack Exchange but it's still in beta so I want to make sure I get some answers :)]


texts: When should we use \$V_L=V\$ when we prove \$P^1_{LOSS}=2P^3_{LOSS}\$.?

texts:
The book said when the transmission power and wire resistance of both one phase and three phase are the same,the power loss for one phase system is equal to two times power loss for three phase ,that is ,\$P^1_{LOSS}=2P^3_{LOSS}\$.

\$P^1_{LOSS}=\$ power loss for one phase system

\$P^3_{LOSS}=\$ power loss for three phase system

However,when i try to prove this relation ,i found that we will regard line voltage as the voltage in the one phase system.I mean

In this proof,i will replace \$\frac{P}{Vcos\theta }\$ with \$x\$, As we can see,

if we regard phase voltage,\$V_P\$, as the voltage when i am calculating the power loss,that is

  \$V_P=V\$,i will have

\$P^1_{LOSS}=2x\$,and \$P^3_{LOSS}=\frac{1}{3}x\$,so it will become \$P^1_{LOSS}=6P^3_{LOSS}\$.

if we regard line voltage,\$V_L\$, as the voltage when i am calculating the power loss,that is

  \$V_L=V\$,i will have

\$P^1_{LOSS}=2x\$,and \$P^3_{LOSS}=x\$,so it will become \$P^1_{LOSS}=2P^3_{LOSS}\$.

This means we should assume \$V_L=V\$ when we are trying to prove \$P^1_{LOSS}=2P^3_{LOSS}\$,but why?why should we assume \$V_L=V\$,not \$V_P=V\$?The reason i think we should use \$V_P=V\$ is that when use \$P=IV=\frac{V^2}{R}=I^2R\$ ,this \$ V\$ should be the voltage of a resistance,this means it should be phase voltage in the three phase system


texts: How to estimate the linearity of this servo from its datasheet

texts:
What parameters indicate to what extent the steps are evenly distributed over a rotation?
Is there such a parameter which indicates that kind of linearity of a servo motor?

--to be updated--


texts:
What's the difference between >> and >>> in Verilog/SystemVerilog?

I know that == tests for only 1 and 0 while === tests for 1,0,X,Z. So how is that similar to the shift operator?


texts: I am looking for guidance of wireless communication between Ubuntu (code written in C/C++) with an Android device. Since the desired range is about 1 mile (~1.5 km), I assume that XBee Pro would be a proper option. Please kindly provide me some suggestions and examples about C/C++ & Java codes and hardware connection. Thanks.


texts:
i want to switch an electromagnet with a 2N2222 & TIP3055
switching should be triggered by a coil passing a magnet as optcal would be to slow
can anybody assist or give us some advice. we don't get it working


texts: What does "Bypass capacitors on both sides of the package" mean?

texts:
I am beginning my first electronics project, which is a PCB that holds a 3.3V flash, and interfaces it with a 5V system for reading and writing.

The model of flash I am attempting to integrate is the S29GL032N, its datasheet is here: http://www.cypress.com/file/202426/download

I am designing the schematic, and reading the best practices document provided by Cypress: http://www.cypress.com/file/323161/download

However there are two points which are confusing to me. It notes that it wants two of two different types of bypass capacitors, located "near each side of the package".

I understand how to place a single bypass cap in a circuit. I also understand how to place two differing types of bypass caps (for example, a 1uF and an 0.1uF cap) to a single Vcc pin. I also understand bypass caps ideally need to have as short a lead as possible to a via which goes to the other side of the PCB into a ground well.

But what I don't understand is the application guidelines clearly state to place two bypass caps of the same capacitance onto a single Vcc pin. It then recommends to place another two caps of a different capacitance to the same pin, seemingly recommending four capacitors to a single Vcc pin. All models in the range only have a single Vcc pin (some models have between one and two Vio pins, but not the one I am attempting to integrate).

If this recommendation makes sense, how would I place two on each side of the package, when there is only one VCC pin?
Is it supposed to look like the picture attached below?
Is there a special reason why two capacitors of the same type are needed for power filtering, and not just one?

Thanks all for your time and help!

Edit: clarity and specifying which chip exactly I am trying to integrate, with a link to its datasheet.


texts: How to calculate the size of ground plane we need to use in a PCB (printed circuit board) design

texts:
I searched about the ground plane and found out the ground plane is a good solution to reduce noise and get a seamless ground.

How do I calculate the size of the ground plane for a PCB?
When and where don't we need a ground plane? (Actually the ground plane is destructive.)


texts: Push pull output stage max output voltage

texts:
Spent a day trying to understand the maximum and minimum output voltage of the basic circuits as shown in this figure
The problem is that I have come across different expressions for the output voltage for these circuits.
My analysis:
Comparing only the high side voltages, or maximum voltage swings in both cases
The circuit on the left: Common source configuration, supposed to have a "rail to rail" swing, which according to me means that the output voltage swings from vdd to ground. Some literatures disagree. Me too. The maximum output voltage for PMOS to remain in saturation is \$ Vdd-Vo>=Vsg - |Vtp| \$ and hence \$ Vo=<Vdd-Vsg + |Vtp| \$. This is not rail to rail. Solving it further, \$ Vo=<Vdd-(Vdd-Vi) + |Vtp| \$ and hence \$ Vo=<Vi + |Vtp| \$. What does this even mean?
The circuit on the right: Source follower configuration, gain is one. The maximum output voltage for NMOS to remain in saturation is \$ Vdd-Vo>=Vgs - Vtn \$ and hence \$ Vo=<Vdd-Vgs+Vtn \$. The same expression as above!!
What am I doing wrong here?
EDIT:
The circuit to the left, if Vo is rail to rail then the PMOS will enter triode region and current sourcing ability will drop drastically, so again how is it rail to rail!


texts: Possible to fry a circuit with a power supply under its current requirement?

texts:
I recently had someone explain to me that he was told he fried a laptop's hard disk by putting it in an external drive enclosure that was not rated to supply sufficient current. (Apparently the disk nominally needed 1000 mA and the power supply was only rated for 500 mA.)

I'm having trouble imagining the chain of events that would result in that letting out some component's magic smoke.

Seems to me that if the drive tried to draw too much current, the power supply's output voltage would sag.

Are there any common modes where an undercurrent results in a fried circuit? My imagination isn't sufficient to come up with any.


texts:
DL 1021
Induction motor with three-phase stator winding and squirrel cage buried
in the rotor.
Technical features:

Power: 1.1 kW
Voltage: 220 / 380 V Δ/Y
Current: 4.3 / 2.5 A Δ/Y
Speed: 2870 rpm, 50 Hz

my question is what does it means for voltage i.e 220/380 V Δ/Y. i did not get the idea Δ/Y(is that starting method or what?


texts: HSPICE create a voltage source in top level and instantiate it in a .subckt

texts:
I am fairly new to HSPICE and I am investigating someone else's testbench and I am trying to track down where is the vsource generator used in the .lstb analysis in this testbench.
I am a bit shorthanded in providing a bigger picture of the problem, but I was hoping just clarifying the used syntax would help me out a lot actually.
So, to narrow it down, I am curious to find the net location where stability analysis was performed.
In the whole testbench file there is only one .lstb call-up, luckily, and there is also only one VV0 mentioned in the file.

VV0 imirrsrc[1] vss dc='p_vload'

.lstb mode=single vsource=XREFGEN.XLOOPBRK.vv0

'p_vload' is undefined throughout the testbench file.
Judging from the way vsource was defined in .lstb it means vv0 is instantiated inside the XLOOPBRK? That is the way to interpret the syntax XREFGEN.XLOOPBRK.vv0 ?
If that is the correct case, I am unsure of how it is declared in the first line then just as VV0 imirrsrc[1] vss dc='p_vload'?
Is this doable?
Or is the correct syntax:

.param p_vload=someValue $assuming p_vload is desired to be defined
XREFGEN.XLOOPBRK.VV0 imirrsrc[1] vss dc='p_vload'
.lstb mode=single vsource=XREFGEN.XLOOPBRK.vv0

I know reading through someone else's work is always cumbersome, but I need help to sort my thoughts on this one...Am I reading into this correctly?

EDIT: I am not sure if I should delete the original text, but here's what I wanted to add so far:
I made my testcases to confirm my rights and wrongs here and I couldn't replicate my question, so my current answer is: NO you can't create a voltage source this way and use it in a subcircuit moreover, you are probably seeing incomplete stuff, and you need the p_vload defined at some point.
It made me realize my question is not good enough.
So, can you create a voltage source in your testbench/toplevel, and then instantiate it (wire it) in a subcircuit right there in your toplevel testbench?
I couldn't do it in my testcases (it failed), but maybe I am missing some syntax knowledge again.
So, is something like this possible:
# toplevel testbench, assuming nodes in MySubckt2 are 2 and 0
xMySubckt.xMySubckt2.V1 2 0 dc=5V

.dc xMySubckt.xMySubckt2.V1 0 5 0.25


texts:
I'm trying to create a project to measure a resitance using electronics and a MCU ADC, and i'm having serious doubts about it and i could use some advices. My first two contrains are that the measure of the resistance as to be done using an AC source and my circuit is powered with a unipolar voltage source. (3.3V)

To create  an AC voltage source i will be using the MCU's PWM (at 100kHz or could be less) and a RC Differentiator Circuit.
This AC signal feeds the WheatStone bridge and the variable resistor,Rprobe, varies between 1 and 100 ohms.
To measure the voltage differential I'm connecting an Instrumentation Amplifier(AD623). My first question is here, since is an AC signal, i will have to power the Amplifier with a Bi-Polar voltage, i heard the i could do it with a charge pump, is it this the best solution?

And about the output of Amplifier, since i want to measure this voltage with an MCU ADC, should i rectify its output using an full-wave rectifier or should i add a DC bias through the Vref pin in the AD623?

Here it is a sketch of my circuit.

I'm looking for all kind of advices and corrections. Any question please ask. Thank you very much.


texts: Why does FZT653 a SMT BJT device have 2 collectors?

texts: The FZT653 in SOT223 package has 3 normal terminals at the bottom, collector, emitter, base. However, it also has a collector on the top. Why is this so? Which is the real collector.


texts:
S.C. test on a transformer gives us the series winding resistances and leakage reactances referred to the same side of the transformer.

My thinking:
Winding resistances, RP and RS do not depend on the current flowing through the windings, they are constants (I think they can be measured more easily by a multimeter).

The leakage reactances, jXP  and jXS are too independent of the current.

Question: So if none of these parameters depend on the winding currents, where does the necessity of passing rated currents through the windings, come into being?


texts: Solar Charge Controller with SMPS Power Supply

texts:
Hi,

I want to charge a 2-Cell Li-ion battery (7.4 V) using CN3722 Solar Charge controller and a SMPS power supply (instead of using solar supply). I have designed my circuit to charge with maximum 1A current. The MPPT voltage is set at 17.5V and the battery float volatage is set at 8.4V.

Thus, through SMPS, I am providing 12V, 1.5A power input to the circuit. In this case, the battery float voltage is found to be 8.4V. but, when i connect my battery to charge it, the circuit is consuming at the rate of 2A by lowering by supply voltage to 10V.

When I increase my SMPS supply current to 2.5A with voltage at 12V and connects the battery to charge it, again my circuit is drawing more than 3A by lowering my supply voltage to 9V.

So, What should be the reason of this problem? Is it due to the fact that I am providing a SMPS supply to CN3722 which is a  solar charge controller. Is it possible to charge a battery through a solar charge controller by providing SMPS power supply?


texts: ESD Protection Diode: I/O Protection on VBUS Line instead?

texts:
I'm looking at a few 4 channel ESD diodes for my USB circuit, specifically the ESD0524P and the PESD2ETH-X. For my circuit, I only need 2 channels, D+, D-, and a channel for VBUS.
Looking at these two diodes, the PES has a Zener for the VBUS line, while the ESD0524P does not. However, I initially connected VBUS to one of the ESD0524P I/O lines which are just normal TVS. Thinking about it now, I feel like this might be wrong.
Can I connect the VBUS lines to the I/O channels of a normal TVS or is this the completely wrong approach? In using either chip, my VBUS line would be connected in parallel to the ESD diode.


texts: This picture is taken from this answer. As far as I know, the bandwidth is the range of frequencies at which the gain does not go below 70.7% of its maximum gain. As we can see the author said when gain is 100 the "bandwidth" is 10,000. How? the graph simply says at frequency 10,000 Hz the gain would be 100, that's all. It does not mean from 0-10,000 Hz the amplifier is going to attain at least 70.7% of it's maximum gain (that flat line gain). So does it mean the the author want to mean "frequency" instead of BW? If no, then what is the actual definition of BW?


texts: Mixed digital/analog rails and level-shifting components best practices

texts:
I am designing a board with a ±2.5V analog domain and a 3.3V digital domain where space is at a premium. Digital and analog grounds only connect at a single point near the supplies. As such I am using/choosing among a few components that have integrated level shifting so as to directly interface with the 3.3V digital domain. Some of the choices are:

ADG788 analog switch
DAC8552 D/A converter
DAC8565 D/A converter

This is a low-noise design where analog signals in the 1µV range will be measured. The main A/D converters do have separate analog and digital supply connections and their Nyquist frequency is 1MHz. This problem particularly applies to the analog switches, but it is much less of a concern for the D/As as either of these will serve auxiliary purposes and will be AC-coupled into the signal paths.

However the 0.8V that the 3.3V rail is above the analog rail introduces problems, as it will bias the protection diodes on some of these components. The same can be said for digital return currents if I connect some of these component ground terminals to the analog ground.

My intended path of action is to:

Connect all (very slow) digital signals to the switches through 10kΩ resistors, thus limiting the current through the ESD protection diodes into the analog supply to <80µA. (The stated maximum for the switch is ~20mA, power consumption in the analog rail is >10mA) With the 0.1µF bypass capacitor these will form a ~200Hz lowpass filter.
Possibly add ferrites to the +2.5 supply rail to the analog switches (after the bypass capacitor) to further reduce any noise injection into the analog supply.
Use digital ground and supply for the D/As. With possibly some filtering of their output.

Does this plan of action seem reasonable?

Is there anything I am not considering?


texts: Solid state relay (optocoupled triac) is extraordinarily hot when on

texts:
I am using the following part: 3-32VDC input to 240VAC max 40A, KD20C40AX, that is connected to an Arduino Uno that drives a 5V control signal to the opto.  The application, (output/triac side), is simply turning on and off a water heater that is running at 240VAC nominal current draw of 18A.  The problem is that when the relay is in the on-state, drawing the 18A, the relay quickly rises to over 200degF in some places.  See the following photo, the orange color is the temperature measured on the side of the relay, in degreesF, and the reddish line is the current in Amps.

What I would like to know is what about this configuration is abnormal?  Is the 5V input signal too low and resulting in a semi-on, high resistance state?  Any recommendations for a less dissipating option?


texts: Custom bootloader passing control to application code in STM32

texts:
I am trying to understand that if for STM32F405 MCU a custom bootloader is used on the MCU then each of the two projects for the custom bootloader and the application code will have their own 'startup.s" files.

What I understand is that both of the two binaries, ie the bootloader and the application code, they both reside at different locations in the flash.

Now when the custom bootloader will exit and return the control then the control should pass-on to the startup code of the application code. But I don't know how it actually happens. Does the two binary programs resides at contiguous locations so that after the bootloader finishes the next instruction is that of the startup code?

Or they are at different locations and somehow the start address of startup of application code is saved as jump address at the end of the bootloader binary?

Will it make a difference in the way it is actually implemented if I use Keil or GCC compiler?


texts: Receive signal from transmitter with PIC

texts:
I have been trying to build a simple wireless setup using the parts enumerated in this post, except I am using a 16f88 pic. Like the poster in the forum I am able to send things from the PIC to the arduino, but unfortunately like the poster I am unable to receive signals from the arduino to the PIC. I have tried what he has done and I have made modifications as well, but I am still incapable of sending and receiving correctly. Right now my goal is to make a LED blink when the PIC gets a 1 from the arduino. I am relatively confident in how it is wired, but how would I make it so I can get good data?
EDIT: When running a program on the arduino to send a 1 every two seconds and a program on the pic to blink when there is a 1, it will flash sporadically and not follow any order. My guess is noise, but I doubt it considering how well the PIC to arduino program worked.


texts: If I had a battery that is 50ah at 30V, what would I have to do to increase the current rating to 150ah, while maintaining the same voltage?


texts: What frequency range is acceptable for a speaker in an audio amplifier

texts: I am building an audio amplifier using a lm386 amplifier with a 12 volt supply driven from a headphone jack.  I am looking for a speaker that will work well in this setup.  Currently I am using a small speaker and their is a lot of distortion in the sound.  I am looking at a speaker that is rated for 1 watt and has a frequency range of 180Hz ~ 10kHz.  I was not sure if this would be good enough for a good sound quality when playing music.  Please tell me if this would work with my setup.  Here is the link to the speaker I am looking at http://www.digikey.com/product-detail/en/GF0771/GF0771-ND/304442


texts: How to extract complex permittivity from a CV measurement?

texts:
I can choose from the following measurements:

Z, theta (impedance and phase angle)
R + jX (resistance and reactance)
Cp-Gp (parallel capacitance and conductance)
Cs-Rs (series capacitance and conductance)
Cp-D (parallel capacitance and dissipation factor)
Cs-D (series capacitance and dissipation factor)

Assuming I have such data for a range of frequencies, how do I extract the complex permittivity?


texts: Is it possible to create a PLL purely in digital design, if so how?

texts:
Provided that we want to reduce jitter on an a periodic input signal (square wave between 0 and Vcc) which is only in some 100 of KHz range, one possibility is to create a system purely using RTL code that shall monitor this signal and generate an output signal of almost same frequency but reduced jitter.
The input signal would be oversampled to determine frequency and an output signal shall be generated from it. Jitter shall cause the measured input signal frequency to change between successive cycles. However, the output signal frequency shall not be changed in such large steps.
Is there a weakness in this approach except that it can only work with input signals of a rather low frequency range than the system clock?


texts: Setting stm32f4 SystemCoreClock to 100MHz but can't get it (only get 57.6MHz)

texts:
I am triying to change the stm32f407 systeme core clock to be 100MHz. To do this I need to set the source of the PLL to be HSE, and configure the PLL coefficient so as to get the right value of SYSCLK.

Here a screenshot of the stmcube that chows the right values of pll M, N, P, Q.

Here is my function

    void rcc_clk_config() // function to configure the rc clk for running on HSE : sysclk at 100MHZ
{
   RCC_PLLConfig(RCC_PLLSource_HSE, 4, 200, 4, 4);//sysclck to 100mhz , systick to 12.5 mhz

       RCC_HCLKConfig(RCC_SYSCLK_Div1);

        RCC_PCLK1Config(RCC_HCLK_Div4);

       RCC_PCLK2Config(RCC_HCLK_Div2);

       do{
          RCC_HSEConfig(RCC_HSE_ON);;

           }

          while(RCC_GetFlagStatus(RCC_FLAG_HSERDY)!=SET);

        do{
                 RCC_PLLCmd(ENABLE);

           }

          while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY)!=SET);
         RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
         SystemCoreClockUpdate();

}

In the debug session I get SystemCoreClock = 57.600.000.

Edit: it works now, here is the new code

{
    RCC_DeInit();
    do{
       RCC_HSEConfig(RCC_HSE_ON);
      }
     while (!RCC_WaitForHSEStartUp());
     RCC_PLLConfig(RCC_PLLSource_HSE, 4, 200, 4, 4);//100MHZ

    do{
       RCC_PLLCmd(ENABLE);
      }

   while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY)!=SET);
   RCC_HCLKConfig(RCC_SYSCLK_Div1);
   RCC_PCLK1Config(RCC_HCLK_Div4);
   RCC_PCLK2Config(RCC_HCLK_Div2);

  RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
  SystemCoreClockUpdate();
}


texts: Incorporating RTOS into a simple sensor interfacing project for learning purpose

texts:
I am trying to switch to embedded from a software test role, and been working on learning about STM32, and almost finishing up writing drivers for I2C which I used for interfacing with a sensor.
I have looked at a lot of job descriptions and most of them do find having an understanding of RTOS essential and I'm wondering if I can incorporate in my existing simple project in any way. One approach I thought of was maybe have two threads with one reading values off the sensor while the other displaying on the screen. Not sure if RTOS is really essential for this specific use-case but just a thought.

Any ideas are appreciated


texts: Arc observing while connecting battery to charge controller

texts:
I have a solar system as shown below diagram.

When I am trying to connect the battery terminals to charge controller, immediately a spark/arc is observing. Does this because of some capacitor getting charged inside the MPPT charge controller? Should I use a fuse between battery and charge controller?


texts:
I have a short question.

I have to read this text regarding the 555 IC:

LINK

As you can see, there is the following sentence:

"Even at 5V, the 555 will easily drive LED's and small relays."

Can someone explain to me what exactly does this mean? Like...

Why is is true?
Why is it important?

Thank you!


texts: Will a dual car charger that shows a maximum output of 2000mA produce a 2.1A current?

texts: I have a dual car charger that states input is 12-24VDC and Output is maximum of 2000mA, but it is supposed to have one port charge at 1A and other port charge at 2.1A. Is the 2.1A output possible with 2000mA or does it have to be 2100mA to produce and output of 2.1A?


texts: Costs of Conductive Silicone/Rubber Keypad vs. Mechanical Switches?

texts:
I am toying around with some new mechanical design ideas.  One thing I've never looked at it is the rubber keypads with the conductive "pucks" underneath.  I've always used mechanical switches, or overmolded silicone buttons onto the finished enclosure for waterproofing.

Example of the conductive rubber keypads: http://www.rubber-keypad.com/Conductive-Keypad-pd6229345.html

I take it the manufacturer gives you a footprint that matches the conductive "puck", and the footprint goes to GND so when the puck hits, your logic line goes low.

Does anyone have any experience implementing these? Are there any gotchas or things to watch out for?

Any experience on the cost side?


texts: Running several lower-voltage items from a higher-voltage supply

texts:
We're running an exhibition that uses lots of 1.5V battery LED torches, which will be on for long periods, and their high-brightness means that using batteries is problematic (continual replacement). I'd like to use a PSU to power them, but don't want to have multiple supplies (or at least, I want to minimise the number of supplies used).

Is there an IC/circuit that can take as input, say, a 12V high-current dc supply, and present as output multiple independent 1.5V sources (each drawing approx 0.7A)?

I can't simply chain the torches I've been given in series, because each one has integral circuitry to run in full/dim/flashing mode according to button pressses, and in series they get very confused...

I even considered buying in my own high-brightness LEDs instead, but the torches (with lenses off) produce very sharp images -- they're being used to project shadow patterns in a gallery -- and so far I haven't been able to find a workable substitute.
(It's bad enough, incidentally, trying to find a high-current 1.5V supply!)

I searched for similar questions, but none seemed to match exactly what I was looking for.


texts: The power coefficient of wind turbine (ratio between useful mechanical power and the total wind power) varies when the tip-speed ratio varies. I know also that we tend to keep constant the power coefficient in tip-speed values of 8-10 (on average, considering a 3 blades turbine) wherein we reach the maximum power and later we tend to decrease Cp when the wind power becomes too high in order to keep constant the power (pitch control for example). My question is: how we keep constant the power coefficient Cp for tip-speed ratio of 8-10? Is this done with converters? And is this done with a MPPT algorithm? (MPPT is the maximum power point tracking). If yes, is it possible to keep constant Cp also with pitch control or active stall?


texts: how to change the structure of the schemetic components in altium designer

texts:
I downloaded a library for microchip PIC18F in altium designer. The schematic component for PIC18F2455 is show in the figure (left).

But what I want is the component looks like - right part of the figure. How to change the structure of the schematic component?


texts: Transfer Function Of Multiple Feedback Bandpass Filter

texts:
I am trying to figure out the transfer function for this bandpass filter (images below).
I am sorry for badly drawn circuit. The operational amplifier is an ideal op amp.

I'd like to know if I correctly analyzed the circuit. I don't think so because when I try to simplify the transfer function into bandpass filter transfer function, something seems to be off.


texts: Coupling between a cable and the main power line: how to measure it?

texts:
I'm wondering what's the simplest way to find the value of capacitive coupling between a cable and the main power line (230Vrms @50Hz, I'm in Europe) to use  afterwards in some SPICE simulations. I know that this kind of value depends strictly to the environment and the context, but this is not the point. In my case, I have two boards connected with some cables on which flow analog signals. On one side (the first board), the cable is connected to the output of an Opamp and on the other side (the second board) is connected to the input of another Opamp configured as buffer. The grounds and the power supplies are the same on both the boards. On the web I found this model for the cable (the component values are indicative)

where the PWR node represents the main power line, C3 and C4 the coupling with the cable and R3 his resistance. To find the capacitance values, I thought to use an oscilloscope and simply connect the probe to the cable under test, keeping this floating in the other end. In this way, if I know the input impedance of the oscilloscope I could find the capacitance. I made a drawing to explain the concept (hope it's clear)

I make two measure: the first with only the probe and I see on the scope the 50Hz interference which is about some mV peak-to-peak (Vo in the drawing); then I make the second with the cable connected to the probe and I obtain a greater interference of some hundreds of mV (Vt in the drawing). With these two measurements I can find Zc.

But now came my doubts:

Is my method good for the cable's model I found? I think no, since the measurement are made on a floating cable which has a high impedance (oscilloscope) on one end and a 'open' on the other. In the real life my cable is connected to an opamp input (high impedance, ok) but the other end is connected to an opamp output (low impedance). Is my thinking correct?
Maybe the most important question: is the model above correct?

What do you think? If you have any suggestions to find (approximately, of course) this coupling value, they are welcome.


texts: What is the use of the capacitor in this relay circuit?

texts:
In the schematic below there is a relay coil driven by a 24V DC battery. In parallel to the coil there is a flyback diode and also a ceramic capacitor.

What is the purpose of the capacitor in this circuit?


texts: Push-Pull driver for low side mosfet -- is it a good idea?

texts:
I want to build an H-bridge to control a 36V dc motor (or possibly 48V but lets stick to 36V for now)

The electronics that will control the H-Bridge (logic, etc) will run from a 12V very-small-like-really-really-low-current source, and I have a bit of a problem regarding the driving of the low-side (switching) mosfets.

I obviously can't run them on my 12V power supply, so I have to use the 36V supply which of course is too much for my mosfets! (maximum Vgs is about 20 volts or so)

What I have come up with is this:

I want to know if such an idea will work, and if that's the case, which of the two pull-down resistors you would prefer? (A or B)

I know that adding the B resistor will cause the upper (NPN) transistor to always be in forward active mode and thus always dissipate power, whereas by adding the A resistor the upper transistor will be in cutoff once the gate capacitance of the mosfet will be fully charged.

For some reason I would feel better if the pull-down was attached directly to the mosfet but maybe I am just paranoid...


texts:
I have a two-wire Pt100 element and a 5V ADC and want to measure the temperature. I have made a wheatstone bridge like below and connected it to an instrumentation amp. No matter the resistance of the Pt100 the output is always ~0.3V. Knowing little about electronics, I suspect this is because the negative terminal is clipped as the op amp is trying to bring it below 0V.

One solution would be to use -5V instead of 0V as Vs-, however I do not have -5V available.

How do you use an instrumentation op amp in such a scenario?

simulate this circuit – Schematic created using CircuitLab


texts: What type of capacitor is the one shown in the schematics as NP?


texts:
I tried to make H-bridge by TIP 122 transistor.
I used 9V for a VCC. I used push button to control H-bridge, and it's fine.
Then I used Arduino 2560 with two digital pins for driving H-bridge. But the output voltage was only 5V. And also, I tried with VCC= 15V, output still be 5V.

Could you please give me an advice?


texts: Put a resistor in series between amp and speaker

texts:
I use a PAM8403 class-D amplifier module (~ 2$ on ebay), which is very good, and stereo.

The output volume is too loud. If I lower the amp's input volume (via software), then obvisouly the output volume is lowered, but there's a noise buzz.
That's why I would like to lower the output volume rather than the input volume.

I noticed randomly that putting a 10k resistor in series between OUT+ and loudspeaker's input makes the volume lower.

It works, I am quite happy with that. But:

1) Is it a good practice? Why does it work?

2) This 10k resistor seems (by ear) to make something like -20dB volume reduction.
Is there a formula to find R for -10dB reduction?

Here is how it looks like:

simulate this circuit – Schematic created using CircuitLab

PS: I don't know my earphones's impedance but I can say it's standard earphones shipped with my Samsung phone.


texts: I'm learning the basics of UART and its features. When I look at published state diagrams for UART then it looks like a Mealy machine. Is it a Mealy machine or did I misunderstand? My understanding is that UART is a FSM type Mealy.


texts:
I'm working on a control system for my school's tropical greenhouse based on the Arduino. It'll just do basic logging things, along with allowing someone to selectively water sections of the greenhouse.

Since I'm not doing a touchscreen (due to dirt and water concerns), I'm thinking of sticking an XBee onto the board (or using a Jeenode) and allowing people to connect to a server stack running on the Arduino to control the system.

Is it feasible to use an XBee as an access point? Is there an easier way to do the interface where I wouldn't have to replace it every few months? Keep in mind that I'm trying to keep costs down, as I'm funding this personally as a high school student.


texts: When i go through a diode datasheet, i saw that the device's package is MCPH3 and bellow that i found SC-70 (JEITA), SOT-323 (JEDEC). Can anyone help me to find out the details about MCPH3. Thank you.


texts:
Let me preface: This is my first post on this exchange, so I will try to provide as much context as possible. If some details are lacking, or I've left this question overcooked, I apologize.

So, I am building a prop for an upcoming convention on the east coast, and part of it involves lighting. I've tried to reduce and streamline the amount of soldering and the like I will have to do, as I am on a budget of time and attempts, so this might seem a bit unconventional: I am making some light-up vacuum tubes with LEDs, and I was going to use the same method outlined here: http://www.instructables.com/id/Glowing-Steampunk-Flash-Drive/

The end result will be the same, however there will be four in total, and they will be powered by a bus-powered USB hub connected to a 16,500mAh battery, which is intended for charging smartphones, tablets, and other devices of the sort.

I wanted to use this warm white surface-mount LED right here: http://www.digikey.com/product-detail/en/lumileds/MXA8-PW35-0000/1416-1094-6-ND/4031757

I believe I can mostly understand the relevance of each field on its little data sheet, but I need to be pretty much certain on a proper resistance.

So the question is, what resistor should I use for it? The Battery has two outputs, both 5 Volts, but one has a 1 Amp output, and the other is 2 Amps. The test current for the LED is 100 mA, and the maximum is 200 mA, with a forward voltage of 3.05 Volts. If I were to use a 22 ohm resistor, would that be proper for achieving ~roughly~ test voltage? Also, would the test voltage be particularly bright? If not, would it be smarter to order two sets of resistors, one for the maximum and one for the test? It has been a long time since I've done even basic electronics.

I just want to make sure I'm understanding this information correctly, and if I'm not, I would greatly appreciate a knowledge smackdown by someone who does. Thanks in advance!


texts: Difference between using large vs small test resistance to check internal DMM/scope resistance

texts:
For my intro lab to my Analog Electric Circuits class, one of the analysis questions is to calculate the internal resistances of the digital voltmeter and the oscilloscope, using the equation

The same applies for the resistance of the scope, just replace \$R_{dmm}\$ with \$R_{scope}\$.
The built circuit looks like this:

with \$V_{in}\$ = voltage \$V(A-A')\$, and \$V_{out}\$ = voltage across \$R_2\$, \$V(B-B')\$.
I ran the same experiment with two different resistors: a pair of 4.7K and a pair of 3.3M resistors on separate trials.
My instructor told me that the internal resistance of the scope is ~1M, and the DMM to be ~10M.
When I run the calculation with 3.3M resistor, I get almost exactly the theoretical values (\$R_{dmm}\$ = 10.19M, \$R_{scope}\$ = 1.004M). However, with the 4.7K I get extremely off values (about 3.3M and -230K).
Here's my raw matlab calculation for the both (sorry for the mess).
%% With 3.3M

vaa=10.088; vbb=4.336;
r1=3.33e6; r2=3.33e6;

rdmm=(vbb*r1*r2)/((vaa*r2)-(vbb*(r1+r2)))

vaas=10.1; vbbs=1.9;
r1=3.33e6; r2=r1;

rscope=(vbbs*r1*r2)/((vaas*r2)-(vbbs*(r1+r2)))

%% With 4.7k

vaa=10.095; vbb=5.044;
r1=4.67e3; r2=4.67e3;

rdmm=(vbb*r1*r2)/((vaa*r2)-(vbb*(r1+r2)))

vaas=10.1; vbbs=5.1;
r1=4.67e3; r2=r1;

rscope=(vbbs*r1*r2)/((vaas*r2)-(vbbs*(r1+r2)))

This lab is due tonight midnight so I'm probably going to just use the calculation with the 3.3M since it returns the right values, but I'm still just curious as to why this is happening (God forbid it's a calculation mistake but I just can't figure it out.) I know that a smaller resistor is better to get accurate voltage values, since the internal resistance will be so high all the current will flow through the test resistor; but in this case, calculating the internal resistance was better with higher resistors.


texts: Why does my electret microphone amplifying and filtering circuit output so much noise?

texts:
Background information
I'm currently designing an input conditioning circuit that amplifies and filters an electret microphone signal in preparation for the signal to be processed by an ADC (analogue to digital converter) and written to an SD card from a micro controller.
The ADC has a dynamic range of 0-5V so I've amplified the signal to an amplitude of 2.5V with a DC offset of 2.5V. The sampling rate of the ADC is 15.625kHz and so I've designed the low pass filter to have 48dB attenuation (8 bit dynamic range) for a frequency of ~7.8kHz and a cutoff frequency of ~4kHz.
As a result of the design considerations above, my circuit consists of an inverting amplifier with a voltage gain ratio of ~6.2 and a 6th order Chebyshev filter with a gain of ~12.
I am using LM6484 op-amps with a 5V supply. The 5V supply is sourced from any device with a USB port, generally a computer USB port is used to power this circuit.
A schematic of the circuit is shown below:

A schematic of the microphone setup:

The 1.5k ohm resistor was specified within the microphone datasheet.
The AC voltage source is used to model the output of the microphone, the 30mV output amplitude was measured with an oscilloscope.
The 1uF capacitor was to remove the bias found when measuring the output of the microphone (2.6V).
The voltage divider into the unity gain follower at the top left of the schematic creates the 2.5V required to bias the signal.
My Issue
Noise. After making a recording I can hear my voice however there is a loud constant humming/ buzzing noise. Sample recording:
instaud.io/Xhu

What I've Tried
I've attempted inserting multiple decoupling/ bypass capacitors at each amplifier IC, before and after long power leads and periodically along power rails on my breadboard.
I've also tried placing an RC low pass filter at the output of my inverting amplifier to cut off any high frequency noise generated by the op amp.
None of my attempts at mitigating the noise has worked or made an impact that is audible in the recording.
My Question
Are there any obvious flaws in my design that could be causing or adding to the noise generated by my circuit?
Could the noise simply be a result of the circuit being built on a breadboard and possibly faulty connections?


texts: Is there any advantage to use a PLL with unitary frequency gain?

texts:
I am not a very experienced firmware developer, so I came across this doubt when I was reading the datasheet of a microcontroller:

In my application, I will use a crystal to generate a clock signal of 26 MHz, the same frequency I want in my system's clock bus. Reading the section that explain about the PLL module, I found the table below:

In the first line, it is shown a use case where the output frequency is the same as the input frequency.

So, my question is: Is there any advantage to make use of a PLL module with frequency gain equals to one, as my source clock is already in the desired frequency?


texts: How do I enable the internal 32MHz clock on an XMEGA avr in assembly?

texts:
This is the C code that I currently use to enable the 32MHz clock:

CCP = CCP_IOREG_gc;
OSC.CTRL = OSC_RC32MEN_bm;
while(!(OSC.STATUS & OSC_RC32MRDY_bm));
CCP = CCP_IOREG_gc;
CLK.CTRL = CLK_SCLKSEL_RC32M_gc;

But this code needs to be compiled with some form of optimization enabled (-Os is suggested). Is there a way to do this in assembly without optimizations enabled?


texts: Why do lights get brighter when I turn on the hair dryer?

texts:
Intuitively, the hair dryer sucks power out of the wires, causing a voltage drop, causing the lights to dim.  But the opposite happens: the lights get brighter.  These are LED bulbs.  It is the heating element that does this, not the motor (running the motor with no heat has no effect on the bulbs).  The lights are on a dimmer circuit.

What causes this effect?  I am assuming it has something to do with the LED power regulator or the dimmer, but am curious to know the details.


texts:
I'm a new student to electrical and electronics engineering. I've been given the following calculations regarding an A.C. circuit with resistors and a capacitor in series, and I'm not sure if I've answered correctly. Any help is much appreciated!

Question:

For the circuit shown below calculate the:
i) Reactance of capacitor C1.
ii) Impedance of the circuit using a phasor diagram.
iii) Power dissipation for resistor R2.

Circuit:

simulate this circuit – Schematic created using CircuitLab

My answers:

i) \$X_C = \frac {1} {(2\pi \cdot 50Hz \cdot 1.5\cdot10^{-5}F)} = 212.2Ω\$

ii) \$Z = \sqrt {(150\Omega)^2 + (212.2\Omega)^2} = 259.9\Omega\$

iii) \$I = \frac {1V} {(150\Omega + 212.2\Omega)} \approx 0.00276A = 2.76mA\$

\$P = I^2 R = (2.76mA)^2 \cdot 50\Omega = 0.14W\$

What do you think? Thanks.


texts:
In shown schematic, I would like to know by any chance or cause if Zener D9 will get damaged. If yes what are all possibilities?

FSK signal consist of 3Hz and 6Hz signal all together.


texts: output impedance without small signal model

texts:
For the mosfet in the figure below, we have:

1. routd = rds(1+gm*rs)
2. routs = (1/gm)*(1 + rd/rds)

Actually, it is not difficult to derive these formulas. However, is there an intuitive way to get this without drawing small signal model?


texts: A question related to "quadrature carrier multiplexing"

texts:
While studying 'Qaudrature carrier multiplexing', I came across these statements in my text material:

"Precisely varying the phase of a high-frequency carrier sine wave in a hardware circuit according to an input message signal is difficult. A hardware signal modulator that manipulates the amplitude and phase of a carrier sine wave is expensive and difficult to design and build, and, as it turns out, not as flexible as a circuit that uses I and Q waveforms."

  Thus practical hardware design concerns make I and Q data the better choice. This way we can avoid manipulating the phase of an RF carrier directly.

Why manipulating the phase directly is not a good choice?


texts:
What's the difference between this two methods of "tap switching"? do they work the same?

simulate this circuit – Schematic created using CircuitLab


texts: Can badly tuned Feedforward still decrease following error

texts:
Let's say we're trying to control the speed of a motor to 20 revs/sec, and we know that our controller output for that speed is approximately 5. We currently have a Proportional controller to drive the motor to our 20 revs/sec setpoint, with some steady state error.

If we included Feedforward, but tuned it poorly, such that it outputs 2 instead of 5, will the following error still be less than it would have been with only the Proportional controller?

I would think that for Feedforward to reduce the following error, the output would need to be able to drive the motor closer to the setpoint than the Proportional controller could do by itself. Is this the case?


texts: Fpga Crossing signals between related clock domains

texts:
I have an fpga design with two clocks, one is 54MHz and the other is a divide-by-4 clock of the 54MHz, this is 13.5MHz clock.

The 13.5MHz clock is generated by dividing the 54MHz clock in vhdl, and feeding it through an internal clock buffer with high fan out. The fpga I work on don't have PLLs.

Do I have to worry about metastability when signals are crossing the related clock domains?


texts:
I have a question about this circuit, using Zener diode as a protection for mosfet. I've found some related topics but didn't found any circuit which uses the same configuration.

Can anyone suggest me that, Is this the correct approach?

The gate voltage is +10V maximum, 0V minimum and VPP1 and VNN1 are +100V and -100V respectively.
Zener voltage for the diode is 15V.


texts: Determining equivalent resistance to find the cutoff frequency

texts:
I am designing a low noise circuit for a precision application and require a stable voltage supplied to the circuit. I have determined that the MAX6250 voltage reference best suits my circuit. A snippet of my schematic can be seen below:

I have added the output bypass capacitor to filter some high frequency noise and would like to know the theoretical cutoff frequency of the low pass filter created by C4. Am I correct in thinking that the equivalent resistance for the LPF is ~0.01Ohm, due to the output impedance of the MAX6250 at low frequencies? Or is the output impedance irrelavent and the resistance is (1k+R_in+500)||R_in, where R_in is the input resistance of the LT1007 (in the giga-ohm range).


texts: Looking for right component in my simple diagram

texts:
I am not electical engineer therefore stumbled upon this simple issue. In need to activate a 120VAC 1HP motor from sprinkler timer that has 4 individual channels providing 24VAC up to 400mA voltage each. When each individual channel being activated in sequence it needs to energize the motor as well.

I used 1A 30V diode for each channel to prevent current backflow.
To activate the motor I thought using relay but most of them at coil have input 24VAC 110mA or below. If I apply 350mA it will burn out the relay coil.
Please see my diagram. Would appreciate if you can give me simple and working design to my application along parts that I can use.

Thank you for your help!!!

simulate this circuit – Schematic created using CircuitLab


texts:
CLA.v
`timescale 1ns / 1ps

module CLA(//CARRY LOOK AHEAD ADDER
    input clk,
    input rst,
    input [3:0] A,
    input [3:0] B,
    output [3:0] seg_an,
    output [7:0] seg_cat
    );

    wire [3:0] S;
    wire [3:0] P;
    wire [3:0] G;
    wire Cin;
    wire [4:0] C;

    bitslice dig0(
        .A(A[0]),
        .B(B[0]),
        .Cin(Cin),
        .S(S[0]),
        .P(P[0]),
        .G(G[0])
    );

    bitslice dig1(
        .A(A[1]),
        .B(B[1]),
        .Cin(Cin),
        .S(S[1]),
        .P(P[1]),
        .G(G[1])
    );

    bitslice dig2(
        .A(A[2]),
        .B(B[2]),
        .Cin(Cin),
        .S(S[2]),
        .P(P[2]),
        .G(G[2])
    );

    bitslice dig3(
        .A(A[3]),
        .B(B[3]),
        .Cin(Cin),
        .S(S[3]),
        .P(P[3]),
        .G(G[3])
    );

    CPGN adder(
        .G(G),
        .P(P),
        .Cin(Cin),
        .C(C)
        );

    wire clkl;
    wire Y;
    wire [3:0] I;
    wire [3:0] out;

    clk_divider clockboi(
        .clk(clk),
        .rst(rst),
        .clk_div(clk1)
        );

    flippyfloppoty two_bit(
        .clk(clk1),
        .Y(Y),
        .seg_an(seg_an)
        );

     mux input_mux(
        .Sel(Y),
        .Sum(S),
        .Cout(C),
        .I(I)
        );

    sevenseg light(
        .I(I),
        .seg_cat(seg_cat)
        );

endmodule

bitslice.v
`timescale 1ns / 1ps

module bitslice(
    input A,
    input B,
    input Cin,
    output S,
    output G,
    output P
    );

    assign S = A ^ B ^ Cin;
    assign G = A & B;
    assign P = A | B;
endmodule

mux.v
`timescale 1ns / 1ps

module mux(
    input Sel,
    input [4:0] Cout,
    input [3:0] Sum,
    output [3:0] I
);

   assign I = Sel ? {3'b0, Cout} : Sum;

endmodule

I'm working on this code for a while and I keep running into issues with the summation part. Allow me to elaborate:

When I perform addition such as X + X, where X is any number/bit, the result is reversed. So for example, 1(0001) + 1 = 20, 2+2 = 40, etc.

My other problem is that some of the math is off. I'm trying to figure out where I went wrong, but can't tell what's wrong with the code and I can't seem to find the issue.

Any ideas would be great, please. Thank you!
Additionally, I'm working on a device where A and B refer to switches.


texts: Calculating Values of ADC for Phototransistor on Digital Pin

texts:
I would like to read a phototransistor from a digital GPIO pin on Raspberry Pi or Arduino microcontroller. Phototransistors are analog devices and to read the value properly I know that I will need an ADC. There are many ADC that would do this for me just fine; however, I am looking for the most cost effective solution. This when I came across this reflectance sensor from Pololu. Here you can see the following schematic (along with some additional details):

This schematic allows you to interact with this sensor on a digital pin of a microcontroller. I would like to modify this circuit to fit my application of just a phototransistor. My question comes into play of how to calculate my necessary values for the resistor and capacitor. If anyone could give me some direction of where to start that would great!
If anyone has any additional questions I would be happy to provide additional information.
Based off some questions I received here is what I am thinking the circuit will look like:

Since it is not a reflectance sensor I can just remove the diode and current limiting resistor. Now comes the question on how to calculate the proper values for R1 and C1. I plan on using the TEPT5600 phototransistor.
The other question was the environment the sensors would be located in. The sensor would be placed in an area that would be relatively dark experience a minimum Lux of around 1 to 5 and maximum of around 300.


texts:
I'm trying to use an L298N and an Arduino UNO R3 to drive a bipolar stepper motor.

To simplify things, I'm just trying to get a 12v output from either output-1 or output-2 of the l298 (then I can write up the 2nd h-bridge in the l298 the same way and be able to drive both motor coils).

I'm only getting ~130mv from output-1 and 140mv from output-2 (measured between the power supply ground wire and output-1/output-2). The motor is a 12v motor, but I've been able to drive it with an l293 which provides only 6v.

I am getting 5v on the logic supply voltage pin and ~4v on the enable pin (using analogWrite(3, 200) - tried with the enable pin connected to either the analog pin 3 or the digital pin 3 (labeled pwm)).

I have measured supply voltage to be 11.85v (12v power supply).
I have followed the wiring/code from here and here (using same arduino code, but they got it to work, and I can't).

I have tried connecting the Current Sensing A pin to the power supply ground as suggested on the 2nd web page.

I have double checked that I have wired it up the same way. I've tried everything on both web pages and the few other pages I can find about building a circuit with an l298n and an arduino and I'm out of ideas about what to try next.

Is there anything I can do?

Here's a picture of what I built:


texts: I have a single phase 230 volt motor.  I am getting 230 volts (115 at each terminal marked with the red line in the image below).  The motor is not drawing any amperage at all and is making no noise at all. The centrifugal switch looks okay. Can it be the start capacitor?  I was under the impression that if the start capacitor was bad it would still pull amperage.  What can I test next to help determine why the voltage is not ultimately getting to the the windings?


texts: running modbus using cat-5e structured cable plant

texts:
We're looking to install some temperature/humidity monitoring in an existing facility. Installing new cabling would be very expensive because of the nature of the plant. Using the existing cat-5e structured cabling would cost nothing. The product of interest  is the Teracom TCW210-TH plus TSH300 Modbus modules, if anyone is interested.

I have a few questions concerning the viability of running Modbus (RS485) over a cat-5e UTP cable plant. I'm unfamiliar with these technologies. With Google I've found somewhat contradictory statements like "not guaranteed above 30m but known to work over much greater distances", and elsewhere references to ~200m being where Modbus over cat5e becomes flaky. Anyone have experience on this front?

Firstly, is it likely to work reliably with a total bus length of around 120 meters? I'm aware that Cat-5e characteristic impedance is 100 ohms, whereas RS485 is spec'ed for 120ohm STP cable.

Secondly, does RS485 reject interference between twisted pairs in a single cable, in much the same way that BaseT Ethernet does?  In which case, could I construct the ModBus daisy-chain using "Y" adapters plugged in to a single wall socket, with the signal coming in on one pair and going out on another? (And similarly in the wiring cabinet). You can certainly run two 10BaseT or even 100BaseT Ethernet links down a single cat5e cable in this way.

The alternative  would be to use an Ethernet connection into each room in the facility and ModBus purely for linking modules within that room. The drawback  is that the data would then be spread out over several Ethernet devices, rather than all conveniently aggregated in one place. The TCW-210 appears to do almost everything we want in its own firmware and web interface, so saving us on programming costs and time.


texts: Schematic notation for decoupling capacitor?

texts:
I'm wondering where this capacitor should be placed. Is it a decoupling capacitor? There are two supply rails on this particular op-amp, so I'm assuming that this indicates I need to put one between each rail and ground. Any insight would be appreciated!

Edit: the data sheet can be found here http://www.intersil.com/content/dam/Intersil/documents/ca31/ca3130.pdf


texts: TL494/TL594 measure current with grounded load

texts: Multiple examples of current limiting with TL494/TL594 suggest to use current sensing resistor between load(-) and GND. But I want load to be grounded. Can current sense resistor be placed above load(+)? Can I use external Rail-to-rail OpAmp this way to measure load current and then use it for TL494 feedback loop?


texts: Effect of wall location for guided wave attenuation

texts:
Pardon my ignorance here if this has already been answered. I'm not fully familiar with the English terminology here so my searches came up empty. If there is any keyword I’m missing or I’m not using correctly, please inform me.

I see several examples of guided wave attenuation for holes in metal boxes to increase the attenuation to/from inside to/from outside of high frequencies. I need to create a fairly large hole here which will most likely cause EMC issues, but not larger than that a small tube could mitigate the problem. Other solutions could exist here as well, but I would still like to understand more about guided wave attenuation.

What would happen if half the length (d/2) of the tube would protrude on the outside and half (d/2) on the inside, instead of all online examples I can find where it's a flush panel on one side and the entire length (d) sticking out on the other?


texts: Safely wiring AA batteries for consumer Arduino product

texts:
How do I safely wire AA batteries to improve an Arduino-like device lifetime?
Discussion here in the Forum [1] and the Battery University [2] suggests that using parallel AA batteries could be dangerous for consumer products due to someone inadvertently using cells that are not well matched. Moreover, it is not clear from the forum discussion (see @Matt. B comments) if series AA batteries do or do not improve an Arduino-like device lifetime. Hence, my questions are:

Is there a way to safely wire parallel batteries thus avoiding misuses?
Does series AA batteries also improve device lifetime even though this configuration does not increase the overall capacity?

Thanks.


texts: Is a stepper motor the best option - if not what

texts:
I have a project where I want to have a 3-400kg mass rotate around its axis.
Based on my calculations, I am looking for a hold torque of approx 100-120Nm

I have considered having a worm drive involved, but the requirement to rotate one way, hold or immediately rotate the other way makes me think that the process will be sloppy with a worm drive in it.

Anyone know where I can find a stepper motor that can achieve my goal, or can you suggest an alternative process.

For the record, this is what I am trying to build

https://youtu.be/wAI02_B6WpY

Thanks


texts:
I salvaged some 470uF 400V electrolytic capacitors from a junk yard. They look like

Why would a PCB contain 2 such capacitors on a board? A motor starter?

Are there any other uses of these capcitors? Say, making a filtered power for audio?


texts: Determining which power supply is connected to our circuit?

texts:
I am designing a small dongle that will have features either enabled or disabled as a function of the supply voltage. I want the device to be low-power and run, for the most part, off a 3V coin-cell battery. However, I am provisioning the design such that the bus may be powered by one of three sources: the 3V coin cell, 4.5V external battery pack, or VUSB.

The motivation for requiring that we know which source is powering the bus is that, to increase operating lifetime, certain features (like seven-segment indication) should be disabled if we are not using one of the two higher-power options (VUSB, or external 4.5V). So, the real problem to solve is how to determine if the 3V coin cell is selected, otherwise we can assume the supplement features can be enabled.

My first thought was to include a difference amplifier in the design. The implementation would have one op-amp input on the bus and the other on the 3V coin-cell rail. Although this should work, it would add a few extra dollars to the overall design cost which, of course, I would like to avoid if possible.

Another options could be something with an on-board ADC by using the 3V as the Analog Reference (AREF). But things begin to overcomplicate at this point and we begin to create unnecessary restrictions on the use-cases of the device (like always requiring the 3V cell be present).

Any suggestions?


texts:
I'm copying the recommended circuit (the 'Higher Performance' one, actually) from the LM1971 audio attenuator datasheet but there are audible (loud) pops on the output.

I'm using OPA227s for all op-amps -- one shared VREF buffer and one output buffer for each channel -- and a regulated 12V supply.  These op-amps have a very low input bias (+/-2.5nA) and high input impedance (10^7Ω), which should prevent these pops according to the datasheet:

  Attenuation level changes cause changes in the output impedance of a μPot. Output impedance changes in the presence of a large input bias current for a buffer/amplifier will cause a DC shift to occur. Neglecting amplifier gains and speaker sensitivities, the audibility of a DC shift is dependent upon the output impedance change times the required input bias current. As an example, a 5kΩ impedance change times a 1μA bias current results in a 5mV DC shift; a level that is barely audible without any music material in the system.

I'm only stepping 1dB at a time, as the datasheet also suggests.  Does anyone see where I'm going wrong, or where else these pops could be coming from?

EDIT: I believe what I'm experiencing is zipper noise, which is prevalent in discrete volume-changing circuits such as this.  Analog devices provides a zipper noise reduction circuit in a few of their digital potentiometer datasheets which seems to only allow the step change to occur when the signal is low enough:

Unfortunately I can't fit this on my PCB but I'll give it a try sometime to see if that fixes things.


texts: stabilized symmetric power supply from battery

texts:
I'm making ECG device and for that I need a dual power supply.

I decided to use 3 x 9V batteries and below there is my scheme:

unfortunately I encountered a problem. I created that power supply using that scheme but after connecting to the output small computer fan, the RPM (and voltage) gradually decreased and finally stopped rotating. construction was hot but after a couple of sec it started to work again but with the same result. where is the problem ? virtual ground ? maybe I should make scheme with 4x 9V batteries ? like this :

greetings


texts:
For a 9VAC-supply, I want an indicator that it's turned on so I hooked up a 1k-resistor and a yellow LED (3mm) in series, parallell over the 9V-source.

The LED lights up in yellow, but it's slowly changing to bright orange over time. While Fluke-ing it under operation it says 3.5V. I think that's a bit high since a loose LED shows 2.3V in diode-measurement on my Fluke.

My guess here is that the LED got too much current and got damaged, hence the bright - and wrong - color. 9VAC is roughly 13V û, meaning 1k gives 13mA through it. Datasheet says "ok up to 20mA, recommended 10-15mA".

Was 1k too low, or what caused the LED to burn?


texts: How to make a DC to DC step up with multiple isolated outputs?

texts:
I want to design a DC to DC step converter with multiple isolated outputs.
I need ten outputs (isolated) positive and GND.

Vin: 8 V DC from LiPo battery.
Number of isolated outputs: 10
Vout: 50 V, 10 mV ripple max.
Iout: 50 mA per output

Is this possible?

EDITED
need to control each isolated output individually from 0-50V using an MCU


texts: How long will my circuit run normally if its battery level reduces?

texts: I am using a 3.7V battery for my circuit. What will happen when the battery level reduces to 3V, 2.5V, etc? Won't some of my components stop working at these low voltages?


texts: What's the difference between virtual circuit switching and circuit switching?

texts:
Circuit switching's packets take the same route as virtual circuit switching's do.

So, how do I distinguish between virtual circuit switching and circuit switching?


texts: Obtaining Plant Input data from System Identification (PID)

texts:
I'm trying to obtain a mathematical model from a physical plant using MATLAB. Using the system identification tool you need the plant input and output data. I'm struggling to match the theory to my practical example.

My plant is a balance beam with a rotor on each end. The plant output is the angle of tilt of the beam, and the input is the motor/s (actuator) command.

What would qualify as a step input on the plant so I can perform System ID? Would it be a step command of X voltage applied to one motor? Would it need to be applied to both motors? Do the units of plant input and output have to match?

Increasing the voltage on one motor would very quickly tilt the beam one way until it's physically constrained by how far it can go. I have concerns about the time it would take to reach that point being sufficient for system analysis.


texts: How should crane remote control diagram be connected?

texts:
could someone please explain diagram for the crane remote control.

What does it means power1 and power2 and drawn coil? What does coil represents?

Also there should be control for up and down (some kind of relay) but in the diagram they are all connected.

If anyone can make sense out of this please help out.

It was from the document: https://fccid.io/JI9-F21-2S-033/User-Manual/User-Manual-1755896.pdf


texts: MOSFET activates every time when ESP32 is restarted

texts:
I am using ESP32 (GPIO-13) and RFP30N06LE to control my load (Motor). Everything works fine until i restart/reset the board, Motor starts irrespective of state (ON/OFF). I tried adding pull-down but it did not work. I want motor to stay LOW/OFF whenever board is Restarted/Reset.

Please refer bellow image for circuit connections.


texts: How does using UART reduce noise when doing wireless communication?

texts:
I am in the process of designing something that needs to do wireless communication across about 6 inches and control a servo. Since I do not have line of sight I am using some really cheap RF chips.

I am a noob at wireless so I threw some stuff together to just see what happens. I hooked up the RF transmitter to a pin on the PIC and wrote to it and then hooked up the RF receiver output to a servo and tried to move it around. This did not work but now I am trying to understand why. It works fine with no wireless comm.

After doing some reading I think it's because there is lots of interference. So I think the fix is to use some data transfer protocol like UART and read it on another PIC and then output to a servo. From what I read this allows me to distinguish my data from the noise. My question is, how does UART allow me to do this? I understand that UART is a way to convert parallel data to serial data with start and stop bits and then to turn it back into parallel to be used on the receiving end but how does this give me the ability to ignore noise? How are the start and stop bits distinguished from the noise?

Is there a way to just use some capacitors for filtering to avoid having any processing on the receiving end? It would be really nice if I could have just a simple circuit on the receiving end with receiver, filters and the servo without any PIC.

Thanks you!

Edit: The transmitter chip is FS1000A and the receiver is XY-MK-5V.


texts: How can I drop voltage from 20V to 12V at 3.5A?

texts:
Here's the problem: I carry around two devices, but at different power requirements - one at 20V/3.5A and the other at 12V/3.5A. I'd like to only carry around one power brick and just carry an adapter cord.

I've looked around everywhere for universal power supplies, but the only one I found that included both 12V and 20V was at 5A. I don't want to risk damaging my batttery at the higher amps.

So now I'm looking to an engineering solution. I have a basic understanding of electrical engineering, but I'm having a little trouble here figuring out what I'll need.

From my research, I believe I can use a 20V/3.5A power supply and a 12V step down voltage regulator. The problem is I can't find any voltage regulators at the correct amps - either too low at like 600 mA or way to high at 20A. Does anyone know where or how I can find the part I'll need?

I assume, using the pinout diagram, I can essentially just run the power from the 20V power supply thru the voltage regulator and come out with 12V. Am I missing anything?

And if anyone has a better solution, I'm all ears (or eyes).


texts: How to interpret microcontroller ADC module on datasheet? Datasheet syntax question

texts:
I am currently working an Atmel micro controller, the EVK1104S, which has the UC32 Data Sheet. We have actually planted this chip on a custom PCB and are in the process of writing more firmware.

Currently, I need to tell the ADC on the Micro Controller Unit(MCU) to sample at 8k samples / second. In reality this is for sampling a microphone. Either way, the documentation is quite unclear (from my perspective) and I was looking for some clarification.

I know that to change the sampling rate I need to change what is called the Mode Register, the register used to configure the ADC for use (pg 799 in the link above). This is the register which allows me to modify the ADCclock.

Example (from pg 799):

ADCClock = CLK_ADC / ( (PRESCAL+1) * 2 )

From what I gather, I will only need to change the PRESCAL to make the ADCClock operate at 8Khz. The problem is that PRESCAL is limited to 8 bits of resolution.

For example, if the controller is set at 12Mhz/x = 8Khz then x would need to be 1500. Because x is limited to 8 bits as I said before this would appear to be impossible, because the max is 255.

I feel that I am doing something wrong here, or not understanding what the datasheet wants me to. Can anyone confirm what I have just talked about or help direct me?

Basically, how can I specify the ADCclock to run at 8KHz if the PRESCAL is only an 8 bit value assuming the CPU is running at 12MHz?


texts: Circuit design and power management in an Arduino project with stepper motors and solonoids

texts:
I am working on a design for a Arduino driven project that controls a 1.7A stepper motor and 2 small solenoid valves. I am using a 12v power supply (Meanwell MDR-60-12) to power the stepper motor (though a TB6600 driver) and the solenoids (controlled by 2 channel solid state relay). I have been using the USB port both to power the Arduino (which supplies 5v power to the relay module) and to monitor the system through the serial port.

I am attaching a diagram of the circuit layout to clarify how I have put all of this together.

As a move forward to finalize this design I have a few questions:

1) Do I need to create a direct common ground between the 12V power supply and an Arduino ground pin?

2) Should I power the Arduino with a dedicated power supply rather than relying on a computer USB port?

3) Should I be including capacitors or diodes at any points in the circuit for added protection?

4) Is there anything else I am missing here?

Thank you - I appreciate any and all constructive feedback!


texts: Left and right circularly polarized antennas - which one to choose for reception-emission?

texts:
I've read that the spiral antenna is circularly polarized, either right or left circularly polarized, depending upon the construction.
I want one antenna be the emitter, and the second one be the receptor.
What should I choose: both antennas right (or left) polarized, or differently polarized?
EDIT: more precisely. I want to built 2 spiral antennas, each one looking to the other at a distance of 1m (that is, one in front of the other). The first antenna will emit at 1 GHz, and the second one will receive the signal. Should I build the two antennas exactly the same, or should I revert the chirality of one of the antennas?


texts: (When) does an SMPS use a push-pull converter to translate the voltage?

texts:
I'm reading up on SMPSs and related technology and have come across contradictory information, or so it seems to me.

Various sources on push-pull converters (for example, the English and German Wikipedia pages, but others, too) will tell you that they are good for transforming voltage efficiently when it comes to high powered applications with a couple of kW and more, and are thus used in SMPSs.

However, any overview on SMPSs I found gave me an AC / AC converter after an inverter / chopper, and then a rectifier after that, like in this picture from the English Wikipedia article:

What I don't seem to understand is why convert to AC for the voltage translation, when push-pull converters apparently are well suited for DC-DC conversion (which is what happens once the input has bene rectified)?

Am I missing something here? Is there different cases where you would use one or the other? Is there a technical advantage to doing the voltage conversion in either DC or AC?


texts:
Will an open loop op amp with negative phase margin oscillate?

I understand phase margin is defined in closed loop transfer function with equating denominator to zero . But will an insufficient phase margin show signs for open loop connected op amp?


texts: Alternative circuit for obsolete product

texts: i am looking alternative circuit or module the same as DTL35A-LC. It is a analog/voltage-controlled current sink module. Its output can reach up to 5 Amps that i really need. So can you suggest a circuit or module replaced to DTL35A-LC? here is the link for DTL35A-LC: http://datasheet.octopart.com/DTL35A-LC-Datel-datasheet-165902.pdf


texts: Class D power supply filtering for conducted emissions

texts:
I have recently designed an audio player that uses the TI TPA3112D1 power amplifier, and mostly based it on the reference design and schematic.  I find however, that the design is failing the conducted emissions test due to noise feeding back into the 24VDC supply.  This noise starts at 340khz with harmonics present proceeding up the freqency range. I assume this to be from the amplifier, as the noise is starts as soon as the amp is unmuted.  The noise is present regardless of audio level output of the amplifier.

I have tried adding different types and variations of bypass caps, which seems to have really no effect.  I also tried a 12uh inductor (AISC-1210HS-120K-T2) I had on hand on the positive supply input, which also made no noticeable difference.  The test house also tried a Steward LFB310190-000, which made little difference.

The PCB is a 6 layer board, the pictures below don't include layers 3 and 4, as there are no traces or planes close to the power and power amp circuit.

The power circuit uses a common mode choke, which probably doesn't target these low freqencies at all.

Googling this is largely ineffective, as most app notes are geared towards emi on the output side of a Class D amp. It may be I need low freqency filtering of some sort, but it isn't clear to me.

Power amp datasheet

My own lab results

Pre and Post 12 uH inductor, prior to common mode choke

24V + and -, with A-B, at output, through common mode choke(It would almost appear to amplify these signals!?)

Attempted fix 1

In this fix, I have cut the traces between the via and the sm caps, routing the supply through the cap leads.  This cap is a 470uf 35v electrolytic.  I have also double stacked 1nf and .1uf on each side.

L4 and L5 are part HI0805R800R-10

Original C12 and C64 100uf 50v are part UCD1H101MNL1GS
Changed to 470uf 35v EEU-FR1V471L

C29 and C13 1nf 50v are part C0402C102K5RACTU

C30 and C31 0.1uf 50v are part C0603C104K5RACTU

Results are no better, probably slightly worse.  The most noticeable difference is caused by touching output leads or speaker body, which causes these spikes/harmonics to approximately double in amplitude. This would seem to indicate that output filtering (L4 and L5) play a part in how this works.

Probe setup


texts:
What would be the max current an 0805 0Ohm 5% resistor can handle (5V-24V) ?

Thanks for your answer.


texts: How to recalculate connections/airwires from copied traces?

texts:
I am learning how to use Eagle, and am designing a breakout board. After routing the connections for the top of the IC, I duplicated and mirrored them for the bottom connections. How do I make Eagle recalculate its airwires and realise that the bottom ones are now resolved?

I tried autorouting it, but this was the result:


texts: Connect batteries with different voltage in series

texts:
simulate this circuit – Schematic created using CircuitLab

I have two 9V batteries connected together in series. I also have a battery connected in parallel with total voltage of 6V and 700mah. I now want to connect the two sets of battery together in series. Is it safe to do this?

Bat3, Bat4, Bat5, Bat6, Bat7 is the second set. I want to make a total voltage of 24 voltage that is why I want to connect this two sets of battery.


texts: the proper way to wire up multiple supply rails

texts:
I am making a hexcopter for a shool project that is going to be powered and controlled via an arduino project.
my current setup is as follows:

Where the linear regulators are the 6 speed controllers' 5v outputs, normally for radios and not motors, that I'm using to power the arduino, and c1 is a brown out capacitor.
**My Problem: **The regulators are slightly different voltages, and the highest output will feed into the lower outputs, which is terrible for the regulators.
I've came up with a solution:

the theory of operation is that if a regulator is (at most) 0.05V off, instead of forcing the linear regulator down to said voltage, this puts a 20 ohm resistance between the two, allowing for (at most) 2.5mA of backwards current. This will also smooth out the load between the regulators, while not impeding any load under 3 amps..

thoughts?

sugestions?


texts: Pitfalls in charging a supercapacitor from a small solar panel

texts:
I'm designing a circuit which occasionally requires small amounts of power (it's switched off most of the time). I want to use small solar panels to charge a supercapacitor, and the cap then serves as an energy reservoir in the absence of full sunlight.

I have already set up a basic circuit with a EDLC supercap (VINAtech, 100F, 3V), a small solar panel (3V, 270mA) and a 1N4001 diode. It seems to work fine, the supercap voltage appears to stabilise at around 2.85V with the panel pointed at the sun, full sunshine and the panels clean. Such ideal conditions will be rare though, the panel may be shaded most of the time. I know that an MPPT charger would be more efficient but I want this to stay as cheap and simple as possible.

simulate this circuit – Schematic created using CircuitLab

In this schematic, V1 is the solar panel, C1 is the SuperCap and U1 is a generic boost converter based on a CE8301A50T. I'm not sure about the final circuit yet, but there will certainly be a microcontroller (Atmega16A) and an HD44780-based LCD with LED backlight. SW1 will only be closed for a few minutes at a time (no more than 15 minutes), very few times a day (probably not at all for several days in a row).

Datasheets: Boost converter IC: https://www.mpja.com/download/ce830.pdf SuperCap: https://www.vina.co.kr/winko/data/product/SS_EDLC_VEC_3R0_107_QG.pdf Sorry, there is no datasheet for the solar panel.

I just want to know if there might be any pitfalls I might have missed. The circuit will operate outdoors, i.e. it will have to survive temperatures of -25°C (-13F) with no problems. Unfortunately, manufacturers don't seem to test the behaviour of their supercaps at low temperatures (as far as leakage current or change in capacitance goes) so I'm not sure if there might be issues. I don't think temperatures will rise above 50°C (122F) in the summer.

Any thoughts?

Thanks!


texts:
Is it possible to solder the panel mounted DC connector shown in the image below on to a PCB? I was unable to find an Eagle library for the same. If it is not possible to solder on to a PCB, any ideas on how I could interface b/w a PCB and such a connector?

Thanks.


texts: 'Jump starting' Lite-eon Server Power Supply

texts:
I have a LITEON Server PSU which I would like to use for an electronics project. For the PSU to 'start up' I assume I need to connect a certain combination of the small pins (that can be seen on photo 2) together (similar to how one 'jump starts' an ATX PSU (example: https://forum.overclock3d.net/showthread.php?t=394).

The power supply specs:
Brand: LITEON
Model: Cisco Catalyst 3K-X 1100W AC Power Supply C3KX-PWR-1100WAC V02

I have tried finding what combination of pins I need to connect together to 'jump start' this PSU but have had no success in getting it to work thus far.

I have measured the voltages over the small pins relative to the two 'power' prongs/pins (the big contacts on the left and right side of the 16 small pins), the two 'power' pins have a voltage of 0V across them (since I have not yet managed to turn on the PSU). Some of the small pins have a voltage relative to the 'power prongs', I have measured all small pin's voltages relative to the left side 'power' pin(negative multimeter wire on left side power pin). The voltages are as follows:

I noticed 2 of the 16 power pins are shorter (these pins' location is marked in the image below):

Perhaps it is not a case of simply connecting two of the pins (or connecting 1 of the 16 pins with GND) but instead it might need a signal originating from the server chassis in order to turn on.. In that case I might be out of luck since I don't have the chassis, only the PSU unfortunately.
(it was suggested in the following link that a digital signal may be needed: https://www.techpowerup.com/forums/threads/how-to-turn-on-power-supply.147023/ (check post #16))

It was also suggested on the same page that there might be a way to open up and find a way to turn it on that way: "Personally I'd open it up and have a look at it. Chances are you can manually trip a relay or jumper a couple solder joints and get it to turn on" (post #7).

It was also suggested that if it were a matter of connecting 1 pin to ground to get it to start this might be a good method of doing it:
"Personally i would hook one end of a ~1k resistor to GND. Probe each wire with the other end. when u find PS-on it will turn on. " (post #16).
Is this a good way to do it, could this potentially damage the PSU?

I have added some photos of the internals but if more detailed photos are needed please let me know.
If any of my explanation is unclear/incomplete please let me know.

Any help will be greatly appreciated, thank you very much! :)


texts: DRV8830 motor controller -- drive is working but brake is not

texts:
DRV8830 datasheet (control register info around page 11).

I have gotten this chip to run a motor with the following code:

void drive(int speed) {
  // Write to the Fault Register to reset it
  Wire.beginTransmission(MOTORA_WRITE);
  Wire.write(FAULT_addr);
  Wire.write(0x80);
  Wire.endTransmission(true);

  // Write to the Control Register
  Wire.beginTransmission(MOTORA_WRITE);
  Wire.write(CONTROL_addr);
  byte regValue;
  regValue = (byte)abs(speed); // Find the byte abs value of the input
  if (regValue > 63) regValue = 63;
  regValue = regValue << 2; // Left shift to make room for bits 1:0
  if (speed < 0) regValue |= 0x01; // Set bits 1:0 based on sign of input.
  else regValue |= 0x02;
  Wire.write(regValue);
  Wire.endTransmission(true);

  delay(100);
}

These are the addresses:

#define MOTORA_WRITE 0x64
#define CONTROL_addr 0x00
#define FAULT_addr 0x01

Here is my code to brake the motor:

void brake() {
  // Write to the Fault Register to reset it
  Wire.beginTransmission(MOTORA_WRITE);
  Wire.write(FAULT_addr);
  Wire.write(0x80);
  Wire.endTransmission(true);

  // Write to the Control Register
  Wire.beginTransmission(MOTORA_WRITE);
  Wire.write(CONTROL_addr);
  byte regValue=(byte)255;//0b11111111 -- I also tried 0b11 but that didn't work either
  Wire.write(regValue);
  Wire.endTransmission(true);

  delay(100);
}

The code for driving the motor works as expected.   When I call brake, however, it does not brake, even though bits 1 and 0 of the control register are set to 1.

I am using an ESP8266 for anyone interested.


texts: voltage shifting from 3.3V to 1.65V with SN74LVC

texts:
I made a circuit to convert 3,3 V to 1,65 V JTAG signals with SN74LVC2G125 buffer. I am using this circuit to program and debug an RF430 chip with a MSP-FET430UIF. I did the same circuit as page 32 SLAU607C from Texas Instruments.
The signals from the debugger (SV2 on the schematic) are good. However the NRST_IN and TDO signals are not good on the SN74LVC2G125 ouput (IC6 on the schematic). Their voltage is 2.7 V whereas I expected 3.3 V signals. The other voltages are good (FET_VCC=3.3 V as expected ; TDO from the chip (pin 7 on IC6)  is 1.65V and RST/NMI=1.65 V as expected ; TCK, TMS and TDI on the SN74LVC2G125 ouput are 1.65 V signals). SN74LVC2G125 is powered with 1.65 V. I don't know where the issue comes from. Any suggestions ?
Thank you for your help,


texts:
There has been some disagreement lately on whether a diode follows Ohm's law or not:
Does a diode really follow Ohm's Law?

Specifically things like

  However, the truth is the resistance of a diode changes depending on the applied current and or voltages.

and

  Ohm's law specifically states that R remains constant. If you try to calculate R from V/I while looking at a diodes IV curve, you will see that as you increase the voltage, "R" will change.

also historically:
Why do LEDs not obey Ohm's law?

  [LEDs] do [follow Ohm's law] - they just do not have a "fixed" resistance

It seems that the main disagreement comes down to what the definition of "Ohm's Law" actually is. Since I was unable to find a question here addressing it, I decided to ask one.

Below are four definitions of Ohm's law taken from a variety of introductory sources on the material. I was unable to find any in more advanced texts, probably because it is so basic it isn't worth including. Therefore, my question: which of these is correct if any. If none, what is the correct general case definition of "Ohm's Law"?

  Ohm's law states that the voltage v across a resistor is directly proportional to the current i flowing through the resistor. Ohm defined the constant of proportionality for a resistor to be the resistance, R. (The resistance is a material property which can change if the internal or external conditions of the element are altered, e.g., if there are changes in the temperature.)

Charles K. Alexander "Fundamentals of Electric Circuits" 4th ed

  Ohm's law is an assertion that the current through a device is always directly proportional to the potential difference applied to the device. (This assertion is correct only in certain situations; still, for historical reasons, the term "law" is used.) The device of [...] which turns out to be a 1000 ohm resistor -- obeys Ohm's law. The device of [...] which is called a pn junction diode -- does not

Halliday & Resnick "Fundamentals of Physics Extended" 10th ed

  Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance,

Wikipedia

  A well known relationship that describes the relationship between Voltage and current through a device's resistance expressed mathematically as V= IR. This formula says that voltage across the device is equal to the current through the device multiplied by the resistance.

electronics.stackexchange.com ohm's law tag description


texts:
I'm a beginner with this type of electronics, but want to try this.

I have a CB radio with a 6-pin mic/controller. The pinout looks like this:

There is a DPDT switch in the mic that switches between receiving and transmitting. I sketched up this circuit with a few transistors and an external battery (3V), will this work to switch between those modes with a SPST button? It seems to work on the simulator but I'm not sure anymore and don't want to fry my radio.

falstad.com circuit

The RX and TX pins are marked with +12V and a series resistor to give the circuit some load but I don't actually know the internal wiring of that, I just need to connect RX and TX pins to ground.

Also, can I connect the Mic to be always connected (the upper pole on the first schematic, that disconnects the mic when only receiving)? That way I wouldn't have to drive that with transistors as well.

Bonus question: is there a way to wire this up so that I don't use any external power source?


texts:
I've recently been trying to figure out an LED driver circuit for my 32V, 0.7A CoB emitter.
I settled on the TPS40211, since it ticked all the boxed in terms of input voltage range, output, etc.

I followed the datasheet design process and also made use of WEBENCH to determine a lot of the component values. However, after more reading I found an application schematic on page 32 of the datasheet (figure 36) that demonstrated a way to drive almost exactly what I need (aside from the input voltage being a little off)

I noticed a few major changes in this topology from the previous straightforward Boost converter schematics. Surprisingly for a TI datasheet, it offered no explanation as to how the driver functioned and what purpose these changes served.

For example, what's the purpose of D2 in reverse bias to the ISNS pin? How does the PWM dimming work with D3, R15 and C14? R6, R23 and R13 also weren't on the other schematics. How is R23 and R13 worked out and what's "loop response injection" for?

I'm really pretty perplexed at this point, but the documentation seems almost too extensive in some areas and totally lacking in others...


texts:
I am looking at a schematic of an amplifier system featuring what I think is some kind of feedback / damping loop on the speakers woofer. I've attached the schematic showing the "damping resistor". I am wondering if someone who is able to read the diagram accurately could just describe how this system works and what its function is. I have highlighted the section i'd like to know about which starts from the negative terminal of the loudspeaker. The application is part of an active loudspeaker unit.

I believe the function might be an attempt reduce distortion?

Edit: now sorted out the schematic


texts: I am trying to make communication system, with serialzing-deserialzing and 8b-10b encding, decoding. Currently I am using the readily available core for 8b/10b encoding, which has a 8 bit input requirement. I want to accept a 32 bit input from the user as a packet. And then feed the 8b/10b encoder with this 32 bits divided into 4, 8 bit patterns, serialize it and send it. How should I take the 32 bit pattern and divide it in 4, 8 bit patterns, when the IP core input demands only 8 bits?


texts: What is the current before arriving a resistor and after leaving it in the wire?

texts:
Suppose we have a very simple circuit, with just a resistor between a wire connected to a power source. What's the actual value of current travelling the wire before and after the resistor? Is it different? Or is it the same across the wire, between the power source?

My guess is that it should be the same, since the resistor limits the current flow, thus create a "congestion" for the current that goes through it. This congestion also slows down the current before entering the resistor and lessen the overall electrons flow through the wire because the resistor is limiting the total amount of electrons that can pass the resistor. So even if the wire can carry more electrons, but the resistor is limiting it, the wire only supplies the amount of electrons allowed by the resistor and the amount of electrons actually on the wire are the same as the maximum go through the resistor. Is this correct?