texts:
I am interfacing two RS422 devices but failing to do so. I started to monitor my device signals and fell into confusion. Please help me understand a few things.
I am attaching snap 01 of my device (LTC2872) data on TX+ line measured with respect to GND.

Snap02 of Standard RS422 to USB Converter data on TX+ measured with respect to ground.

Question 01. From LTC2872 Snap01 I get data as per theoretical concept. With data appearing in Snap02, why are there extra bits appearing here? Data length should be 1.04ms at 9600 8N1.

Question 02. Why are the voltage levels of both devices different? How do I match this level?

P.S: Differential Signal (A-B)

Differential Signal measured A w.r.t B


texts: Colpitts Oscillator, hard time finding values to use

texts:
I am having a hard time trying to find a logical way to find values for capacitors and inductor to build this circuit (colpitts oscillator)
I read this great tutorial
and I have simulated the circuit and its works just fine. Now I would like to build it with components I have.
I have a lot of capacitors too many values to name but I do not happen to have the values used in the example on the website. So I ask is there a way to manipulate the formulas or something that is not catching my eye as far as choosing capacitor and inductor values?

I know that:
Xc1 + Xc2 = XL

So in my mind I think ok let me choose two caps and from there figure out what
inductor I need, but in order to that i need a resonant frequency to derive my capacitive reactance values, but i cannot do that without my inductance value. So i have 3 unknowns capacitor values, inductor value and resonant frequency value. With the catch that Xc1 +Xc2 = Xl @ resonant freq. To make it even more fun the feed back given by C1/C2 cannot be too big or too small.


texts: I am new to the world of electronic repair. I have connected several wires to this board and have been successful in getting the paths across the crack to connect. Is there an easy way to trace out the wire paths? I have been following the lighter green path, connecting the wires across the crack. Again, I have been successful at getting it to work just curious if there is any information on following the circuit without a schematic. Thanks!


texts: I measured ph-ph voltage (l1-l2) equals 100 v, (l1-l3) & (l2-l3) equals 55 v. However, when I measured ph_n equals 55 v for the 3 phases. I tried to measure earthing but all neutral points all well earthed.


texts: KiCad PCBNew Change or Customize Color of Rats Nest

texts: Is there a way to change the color of the rats nest that PCBNew uses?  Ideally I'd like to be able to set the color of a specified net; specifically the GND net.


texts: Nodal Analysis: Resistor in front of Node A

texts:
In this section from a circuit, Va has two voltages going to it, but also has a resistor going to it as well.

Most nodal analyses I've seen look like this. So Va is very easy to find. The resistor in the way of the voltage confuses me. What would you do, given the situation.

This is the full circuit


texts:
I am looking for a way to counteract an active servo or stepper motor.

In more detail:
I want to translate the movement of a controllable motor to a linear rod movement.
This rod goes up and down continuously up to a certain threshold.
The user should then be able to push the moving rod down to establish a new - lower - threshold. Also the user should be able to pull the moving rod in order to establish a new - higher - threshold.

I read you can use a servo both as input and as output but not on the same time. Is there any motor that can do this? So it should actually let go upward movements when a certain push force is applied to the rod.

I would really like to use as little components as possible since the final installation should be a multiplication of this a quite a small space.

Thanks in advance for thinking with me!


texts: Are carry flags set even when we discard the carry in an arithmetic logic unit?

texts:
Currently I am learning simple binary math for a microprocessors course and have a trivial question on signed addition in 2's complement notation.
My professor mentioned that when we substract two numbers (to be precise, addition with a negative number) a carry is generated which is not an error and which can be discarded. Some examples with 8-bit signed numbers could be as:
   1111 1111 (-1)       0010 1000 (+40)
+  1111 1110 (-2)     + 1110 1100 (-20)
------------------    ------------------
 1 1111 1101 (-3)     1 0001 0100 (+20)
 ^carry discarded     ^carry discarded

Now, a carry is generated, but it does not indicate an error as without it the result is correct and we discard it. My question is, how the arithmetic logic unit handles this, knowing that binary adders don't know about signed/unsigned numbers. And if we take a look at a simple Full Adder circuit, the carry generated from the most significant bit is directly transferred, so the carry flag should be set if there is a carry.
But then how does it work when we need to discard the carry? Wouldn't it cause problems in consecutive arithmetic operations where an operation's carry-out becomes the other's carry-in?


texts: How much Should a Diode Read on a Multi Meter?

texts:
I'm trying to self learn all this stuff as I am a programmer not a engineer by trade So any help will be great.

I have a Samsung TV Model : UA46B7000WF

The Problem is that the TV blew a fuse which i then replaced and then that fuse blew to, so I decided to check the diode on the power board (Image Below) so One Diode Read 465 and One Read 467 so here are the things I am wondering:

Has the diode shorted? I was watching a couple of Youtube videos and it said that it should be between 500 and above and other places 400 and below so I am not sure if it has shorted or not
Is there some sort of chart available that I can use and learn to check what each diode, register, capacitor should read on a Multi Meter? I am trying to learn and understand any good learning resources will be great

Thanks


texts: When are you required to use {} braces around an expression, and when can you optionally use braces? I realise that this is simulator-specific, and different simulators seem to have different requirements. I think that the original 'correct' answer would have been that only parameter names, or alternatively expressions which include a parameter name, should have braces around them, but I'm not sure, and any sim-specific replies would be useful.


texts: Twoport T-Network - Why does the voltage increase?

texts:
I am new to electrical engineering and currently struggling to understand following network:

Activating both current sources and using arbitrary values for the currents and for the resistors i get a higher voltage for U_1 and U_2 in comparison to when i only activate one current source.
It just isn't intuitive for me. I imagine to water pumps; why should one pump increase the pressure of the other pump and vice versa?


texts: How do I Drive High Side MOSFET in High Voltage Low Power DC-AC Unipolar Converter?

texts:
I'm working on a simple dual stage piezoelectric driver consisting of a DC-DC flyback converter (programmable from 50V to 250V) and a DC-AC half-bridge unipolar inverter.  The flyback converter is working great!..But I'm having trouble with the DC-AC stage.
The DC-AC stage takes the high voltage DC generated by the flyback converter, and creates an arbitrary high voltage (0v to Vboost) at V_out when Q_high (increases voltage) and Q_low (decreases voltage) are pulsed on/off.  Using a voltage divider for V_out feedback, I compare the output voltage to my desired reference waveform in my processor's memory and generate the necessary pulses to create the arbitrary waveform (Square, Triangle, Sinusoid, sawtooth etc.).
Currently Q_high gate is being driven by my MCU at 5V, which is obviously not high enough to produce the Vgs needed to keep the transistor on as Vout rises.
I've started reading up on gate drivers, and bootstrap circuits.  The IRS20752LPBF Gate Driver grabbed my attention, but I'm concerned this device won't work when my load V_out voltage changes as a function of time.
So my question for everyone: what is a good method for controlling the high side MOSFET, given V_out is an AC (unipolar) waveform?  And can I just use a gate driver in this application?
My Assumptions:  I don't need a bootstrap circuit to control Q_high, since I am fine with keeping V_out 5V or more below V_boost.  Second, I can't pull Q_high up to V_boost when I want to turn it on, and GND when off, since that will violate the maximum Vgs ratings; I need to be more clever and drive the gate with either V_out (off), or Vout + Vth (on).


texts: Crosstalk from RX to TX line on the RS-232 side of MAX3232C

texts:
We have a product which is using a MAX3232C for interfacing to a PC. Its RS-232 RX line is tied to the MAX3232's R1IN pin and its TX line to T1OUT:

The problem we are having appears to be some kind of crosstalk between the RX and TX lines.

This scope image is showing exactly the same bit stream received on RX (yellow) coming out of TX (green), but with a little distortion and a smaller amplitude (the TX bit stream following the "crosstalk packet" is just the expected answer packet from the device).

The baud rate is rather low (9600 bps), so we wouldn't expect to see that due to PCB design issues. To rule out a PCB problem, we exchanged the MAX3232C from Texas Instruments for a pin-compatible device from ST Microelectronics, an ST3232C, and the problem vanished:

That said, has anyone ever experienced a similar problem with MAX3232? Can anyone imagine other possible causes for the problem other than a faulty I.C.? Just for the record, we observed the same problem with other units also using MAX3232C devices.


texts:
I am using a FTDI's UM232H usb-i2c adapter to communicate with MAX6615 temperature monitor device and DLVR pressure sensor. I developed a I2C routine to talk to these above mentioned devices. I can able to communicate successfully with max6615 device. But i couldn't be able to communicate with DLVR sensor. The DLVR sensor doesn't acknowledge. I also tried different clock speed. But no luck. Surprising part is , i can able to communicate with the same DLVR sensor using Aardvark adapter. Now i am confused , if it is a SW  or HW issue. The code that i developed works with other i2c device but not with DLVR sensor(which proves the code is good).On the other hand, I can able to read from DLVR sensor through aardvark. (so i guess HW is good too).
The slave address i used is 0x28 as mentioned in the data sheet.

Any idea how to debug this issue?


texts: How to select a gate driver for a 100% duty cycle MOSFET switch

texts: I am designing circuit with a high-side N-channel MOSFET switch. The switch will be operated at 100% duty cycle. I decided to use a high-side gate driver since they have internal circuitry to boost the gate drive voltage to the required levels. My first prototype used a IRS10752LPBF but I quickly discovered that the "bootstrap" configuration could not operate at 100% duty cycle. I am redesigning and looking for a gate driver appropriate for this application. What sort of gate driver must I select to operate at 100% duty cycle?


texts: Connecting RGB led to the output of the op amp with resistor

texts: I want to connect RGB led to the output of the LM741 op amp.Do I need to use BJT ? If I don't .Can op-amp  provide enough current to RGB? Secondly ,Can I connect 3 pin of the RGB to the output without buffer?


texts: How does this iPhone app measure the power flowing through an AC appliance cord?

texts:
My electric utility released an iPhone app called "DTE Insight" which (among other things) measures the amount of power flowing through an appliance's power cord by asking you to hold the cord against a specific part of the iPhone at a specific angle. I tested this app against the measurements from my Kill-a-Watt, and the app seems remarkably accurate to the point where I don't really understand how it works.

I understand that current flowing through a conductor creates a magnetic field around the conductor, and I imagine that this app is using the phone's magnetic field sensor to try to measure the magnetic field caused by the current flowing through the cable, then multiplying the calculated current by an assumed voltage of 115 or 120 or whatever in order to estimate power.

What confuses me is that household appliance cables contain two current-carrying conductors. Wouldn't the opposing magnetic fields from the two conductors interfere with and almost completely cancel out their respective fields out in the area around the cable? The app does ask whether the cord being tested is a two- or three-pronged cord, and whether the cord is round or flat. Can anybody explain to me how this might work?

Data

I did some tests using the app and my Kill-a-Watt to measure power draw of the same loads. I did five trials of each of the four loads using the app. The loads were:

Assorted computing equipment sharing a power strip
An electric fan on low
An electric fan on medium
An electric fan on high

The results are as follows:

Compute Load:

Kill-a-Watt: 632 W, 757 VA

App: 678 W, 667 W, 623 W, 662 W, 644 W

Fan on Low:

Kill-a-Watt: 56 W, 57 VA

App: 75 W, 75 W, 75 W, 75 W, 77 W

Fan on Medium:

Kill-a-Watt: 75 W, 75 VA

App: 103 W, 101 W, 98 W, 100 W, 97 W

Fan on High:

Kill-a-Watt: 97 W, 102 VA

App: 132 W, 129 W, 131 W, 128 W, 131 W

Reproducibility

If you want to try this yourself, you have to select "Tools" and then "Take a Power Scan" from the main menu of the app.


texts: Verilog - Using 'define' to declare a constant created by a 'parameter'

texts:
Pardon the wordiness of the question's title. How would you accomplish the following. I have this parameter:

parameter BUS_SIZE = 16;

And I want to use it later in the code to declare some constants. Currently, I am doing this:

someReg <= 16'h8F;

The hardcoded 16'h8F means that the code is not flexible, and defeats the purpose of the parameter.

What is the proper way to declare this constant? This is what I've come up with, but I'm not sure it would work or if there is something more elegant available:

`define dBUS_SIZE BUS_SIZE
...
someReg <= `dBUS_SIZE'h8F;


texts:
Hello I have a question regarding the operating characteristics of 3 phase AC voltage controllers, the images describe the relation in between Van and (VAC,VAB,VBC)

The last image shows the resulting waveform when the respective thyristors are conducting (on), however i am confused as to why there is a voltage of zero when 2,3 and 5,6 are on.

I drew in green what i would expect the waveform to look like at that stage.

If anybody with experience in power electronics could explain this, it would be greatly appreciated.

thanks


texts: API portability for ARM Cortex (Xilinx Zynq 7000) with PowerPC (Xilinx Virtex 4)

texts:
Are the APIs(or tools) used by "PowerPC Hard Macro" to integrate with Virtex 4 similar in the case of ARM Cortex with Artix 7(in Zynq)?

Ideally it would seem so since Xilinx would keep it that way for usability, but I wanted to be sure.


texts: Calculating MOSFET gate current with \$Q_\text{total} = I_\text{gate} \cdot t\$

texts:
Hi I am using the MOSFET IRFP4368. I want to use the equation
$$
Q_\text{total} = I_\text{gate} \cdot t
$$
to calculate the required gate current of my MOSFET driver. I have my total \$Q_\text{total}\$ from the data sheet. I am not sure what \$t\$ would be in this instance. Is it the \$t_\text{rise}\$ given in the data sheet? Or something else?


texts: Check content of EEPROM during run-time like Visual Studio

texts:
In Visual Studio, when we try to read memory location, we add breakpoints and run step by step to see what is getting read or written to a memory location.
Is there a similar way, we can do it in MPLAB v8.85 IDE with PICkit3 to read PIC16f685.

Basically, I have a code for this PIC which reads as well as writes data to EEPROM. However, to see what data is getting read or written I am trying to see it work step by step so that I can know what data is read. Can anyone help me with this?


texts: How find the optimal frequency of a high frequency transformer

texts:
I have disassembled a "Chinese" power inverter, I found a High-Frequency Transformer, with no label on it.

I would like to make an inverter using this transformer to generate the High voltage to feed into a full bridge to make a pure/modified sine wave inverter.
I "I reversed engineered" the inverter, I found that the transformer was driven in the following way(using center tapped transformer instead of a full bridge):

The question is, how I can calculate the best/optimal switching frequency for this HF transformer, assuming I can measure its resistance and inductance?

I need to know where the core saturates and then apply the reverse of V=4.44*N1*f*Bmax?

How the switching frequency will impact the performance(voltage ripple, idle current, losses)?

How PWM modes(Center aligned vs edge aligned ) will impact performances, assuming that both MOSFETs will be driven with the same duty cycle(regulated by a PID / PD loop on output voltage), but 90 degrees apart?

And I need to put flyback diodes in parallel with the n-MOS?

Thanks in advance.


texts: Proof for Peak Time for an Underdamped Second-Order System

texts:
I've been attempting to prove the taught result that:
$$T_p=\frac{\pi}{\omega_n\sqrt{1-\zeta^2}}\textrm{.}$$

From the time-domain form of an underdamped response, we have
$$c(t)=K_1e^{-\sigma_dt}\cos(\omega_dt-\phi)\textrm{.}$$
In an attempt to find maxima, the first derivative has been found as
$$\frac{dc(t)}{dt}=K_1\left(-\sigma_de^{-\sigma_dt}\cos(\omega_dt-\phi)-\omega_de^{-\sigma_dt}\sin(\omega_dt-\phi)\right)\textrm{.}$$
From here, assuming \$K_1\textrm{, }e^{-\sigma_dt}\ne0\$, the maxima are found at
$$\omega_d\sin(\omega_dt-\phi)+\sigma_d\cos(\omega_dt-\phi)=0\textrm{.}$$
Re-arranging for \$t\$, we find
$$t=\frac{-\tan^{-1}\left(\frac{\sigma_d}{\omega_d}\right)+\phi +n\pi}{\omega_d}\textrm{.}$$
The denominator clearly aligns with the taught result, as the damped frequency is related as such to the natural frequency. However, I do not see how the numerator aligns to \$\pi\$. Where does the \$\tan\$ term go? I'm aware that we're hunting for the first peak, so it makes sense for \$n=0/1\$? Any help would be appreciated.


texts: How would magnetic wire (not magnet wire) affect the inductance of a coil?

texts:
Suppose that magnetic wire with resistivity similar to copper but with non-negligible permeability existed.  What effect would magnetic wire have on the coil inductance versus a copper coil of the same size/construction?

This is of course a purely academic exercise, since such a material does not exist, though it could perhaps exist for plated wire at high frequencies, due to the skin effect.

EDIT:

I guess it's not entirely academic.   isdi pointed out that "high permeability wire" actually exists.

According to this:

  Mu Metal Wire is used in the production of inductors and electrical transformers. It has one of the highest magnetic permeability ratings of any metal or alloy, making it an industry standard in applications where metals with high magnetic permeability are needed.


texts: Equipment to measure strong constant (in time) and slowly changing electric fields

texts:
I would like to measure the electric field in the vicinity of an object of interest. I would like to have decent spatial resolution (i.e. be able to pinpoint a measurement to a point in space within an inch or so). The electric field might be (time) constant, or it might be changing slowly (up to several kHz). If the same piece of equipment can't handle both, I will be completely satisfied if it is able to measure constant field. It doesn't have to be too sensitive - the fields I expect are on the order of kV/m. I've been searching the internet for a piece of equipment to do this, but without much luck. Here are a few things I found:

I found this straightforward application in a book but I can't seem to find any equipment employing this idea.
I could use a sensitive electrometer to measure induced charge on an antenna, which should be proportional to the electric field. I'm not sure how well it will cope with changing field.
An electric field mill, which is a similar idea to the electrometer, but the ones I saw were quite bulky, intended for atmospheric measurements.

What would you recommend?


texts: 4 bit even odd parity checker/generator using logic gates only

texts:
Hi i am working on my digital electronics project 4-bit even odd parity generator and checker this is my circuit.how do i implement this on breadboard and what am i missing here except the vcc and where to place the led's to show even odd.
Thanks


texts: MAT01 Matched NPN Transistors - Substrate bias voltage

texts:
I am working on a logarithmic amplifier based around the MAT01GHZ matched pair.

In the datasheet, a note states:
The collector to base and collector to emitter leakage currents can be reduced by a factor of 2 to 10 times by connecting the substrate (package) to a potential that is lower than either collector voltage.

Since I am operating from a ± 5V supply, is it advisable to directly connect the substrate (via a case connection) to -5VDC, or should I supply a smaller magnitude negative voltage, for example by connecting the substrate to the emitters? One collector sits at a virtual ground point and the other is a few hundred mV above ground.

The MAT01 does not have integral protection diodes, unlike other transistor arrays, such as the MAT02, MAT12, CA3046. For the latter, the substrate is usually connected to the most negative point of the circuit, but I'm worried I might cause damage and mismatching, as I'm unaware of the structural relationship between the transistors and the substrate.

Thanks!


texts:
I want to control the power supply of a sensor with a microcontroller, so I can turn it off when it isn't being used.  My goal is to minimize power consumption on a battery-powered device.

Both the microcontroller and sensor are running on 3.3 V.

Can I use a single MOSFET directly driven by the controller?  Or is there a better method?

atmega328p micro controller and GY 61 accelerometer sensor are used.


texts: Mistakenly performed continuity test when power is on

texts:
I forgot to turn off the power of system before I did some continuity test using a multimeter.

Basically an +-V dual supply was powering a transducer. Transducer was outputting very small offset like 100mV and had almost 8k output impedance so I'm not worried about that much.

But I also did continuity test between V+ and V-; V+ and GND; V- and GND ect.

When I each time heard continuity sound I noticed that I forgot to turn off the power. So I turned off and did the same test.

But many hours later I was afraid if I did damage the power supply.

What happens if nodes +15V and -15V or + for instance is checked with continuity of a multimeter when the power is on? I know that would be short if it were a wire but is there possibility power supply is not damaged?


texts: STM32 DAC triangle generator flat bottom

texts:
I'm trying to create a triangle signal with DAC via DMA (STM32F407VG DISC1 board). My template array is fine, I've checked it with a plot. But I have some strange flat area on the bottom I've stuck on. I've tried to pull it up to avoid touch of the bottom but it doesn't work. What could be wrong? Here is all related parts of my code:
// DAC VAWE BLOCK
uint32_t signal_val[SIGNAL_TEMPLATE_SIZE];
uint32_t signal_ampl=1240; // 2v
uint32_t signal_freq=450;
uint32_t signal_type = 1; // triangle

void calcsin ()
{
    for (int i=0; i<SIGNAL_TEMPLATE_SIZE; i++)
    {
        signal_val[i] = ((sin(i*2*PI/SIGNAL_TEMPLATE_SIZE) + 1)*signal_ampl) +5;
    }
}
void calctriangle()
{
    for (int i=0; i<(float)SIGNAL_TEMPLATE_SIZE/2; i++)
    {
        signal_val[i] = (i/((float)SIGNAL_TEMPLATE_SIZE/2.0f))*signal_ampl*2 +5;
    }
    int j=(float)SIGNAL_TEMPLATE_SIZE/2;
    for (int i=(float)SIGNAL_TEMPLATE_SIZE/2; i<SIGNAL_TEMPLATE_SIZE; i++)
    {
        float b = (j/((float)SIGNAL_TEMPLATE_SIZE/2.0f))*signal_ampl*2;
        signal_val[i] = (uint32_t)(b) +5; //+5 anywhere to up wave just a little and prevent it's corruption on bottom
        --j;
    }
}

  if (signal_type==1)
      calctriangle();
  else
      calcsin();

 HAL_DAC_Start_DMA(&hdac, DAC1_CHANNEL_1, signal_val, SIGNAL_TEMPLATE_SIZE, DAC_ALIGN_12B_R);


texts: How to use LM56 to switch on/off a 2kW heater

texts:
I have an oil heater at 220V/2000W so lets say 10A. I was thinking of creating a circuit to switch the oil heater on/off with a LM56 (http://www.ti.com/product/lm56). Is it possible using a relay or optocuplor? I don't have experience with high-power devices.

Thanks!


texts: FT232RL USB to serial : 5V or 3.3V set by jumper

texts:
I've just bought a cheap FT232RL USB To serial adapter (EAN: 0680004529143). It does not come with a manual and the short description simply mention:

USB power supply, can choose 5V or 3.3V ,set by jumper.

However starring at it I cannot see anything that would looks like a jumper. Here is the view from the top:

And here is the view from the bottom:

Anyone has a schematic of what needs to be done, and where is this 'jumper' ?


texts: From pulse height to number of electrons

texts:
Assume that there is a pulse on a scope with \$100\;mV\$ height, as shown in picture

This pulse is coming from a photomultiplier tube. How to determine the number of electrons from which this pulse is constructed?


texts: Intriguing obsolete(?) PCB manufacture techniques in this old MSX

texts:
Browsing Wikipedia (as one does), I have stumbled upon this picture of a circuit board¹:

Now, when you look at it, there are several things that stand out as  being interesting and different to today's commonly used PCB manufacturing techniques.

I don't have access to the board pictured, but here² are some more pictures of it. However I do recall seeing other circuit boards using these techniques; especially on lower-cost devices from the late 80s/early 90s and remote controls.

So, here is what I'd like to find more about:

Multiple soldermasks?

There seem to be at least two levels of soldermask. One of which is visible only around the vias, and the other opaque one covers and conceals stuff further.

What's the purpose of this second, very opaque layer?

To hinder reverse-engineering of the PCB layout. This however doesn't make that much sense to me, since the PCB pictured comes from an MSX computer, and AFAIK the MSX architecture was pretty much an open standard. Also, this additional opaque layer is absent on the bottom side.
Or is this not just an opaque soldermask, but that and another (rough) conductive layer over another (what you'd think of as traditional) soldermask; which would make some sense here too, perhaps for EMI shielding. Is this it? Another thing going for it is the large clearance around the vias.
Or is it something else entirely?

Blue vias

Don't the vias look interesting? How were those made? It seems that they did not use (now ubiquitous) plated through-holes manufacturing this board.

But what is this that they used instead and how were those made? Is this some sort of conductive epoxy?

The (relatively) large via size could be justified by it. It also seems like the material over the vias is rather concave with likely designed-in overlap over exposed copper around the hole. Were those filled-in one-by one?

Now, why did they use this method instead of the "modern" PTH? I suspect it must have been significantly cheaper for small enough number of holes. What would this method be called?

Searches for epoxy-filled vias do yield results, but of different-looking ones to this.

This is my first question here after all this time; I know however that having multiple sub-questions is sometimes frowned upon, but I hope this still counts as being reasonably related enough. Thank you for your answers.

I also hope some others find this as interesting, with the epoxy via technique perhaps finding another life in my homemade PCBs.

¹) Image taken from Wikipedia by Yaca2671. Wikimedia link

²) MSXinfo.net article on Panasonic FS-A1WX


texts: Combine DC voltages from solar panel and grid

texts:
I have a large number of DC-powered devices: most of them can operate off 8-23V. I currently run them off a mains 12V power supply. What is the most efficient way to power them off the solar panels when the sun is shining, and off the mains power supply at night or in bad weather.
I can custom design switch mode power supplies, with FETs to switch between solar and power supply: but would work any better than using two big diodes?


texts: Speed up or slow down motor of cassette recorder using a potentiometer

texts:
Background: There is a cassette recorder (RadioShack CTR-80A) and its owner would like to have the ability to speed up and slow down the motor to record  and play the sound in a distorted way. We've done a similar thing already to a Sanyo TRC-3460 voice recorder, but its diagram was easier to understand.
Question: Where in the following diagram one would put a potentiometer to achieve a distorted effect (slow down or speed up a bit) when recording or playing audio from a cassette? What value should that potentiometer have?

Also, could you please point me to the resource describing the symbols which are used for switches in this diagram (the ones with white and black triangles). I've search high and low and do not understand what they mean. Well, not well enough, anyway.


texts: How to choose correct inductor from calculated values for a TPS562219 stepdown

texts:
I'm trying to build a step down module with a TPS562219: http://www.ti.com/lit/ds/symlink/tps562219.pdf

On page 14 there is the reference design and on page 15 I can calculate the values Il p-p, Il peak and I LO(RMS). Therefore the datasheet shows an example for an 1.05V output:

Il Peak = 2.34A
I LO(RMS) = 2.01A

With that they recommend an inductor with a peak current rating of 5.5 A and an RMS current rating of 4.3 A. I don't understand why they choose such different values from that what they calculated.

In my case I need to get an 5V output for an 12V input. So my calculations give me the values

Il p-p = 0.95A
Il Peak = 2.477A
I LO(RMS) = 2.0189A

Which leads me nearly to the same thing. So I would choose the same inductor? If this is correct, then I don't understand why to calculate the values, if the result is always the same.

And just by the way: Are R2 und R3 in Table 2 (page 15) named correctly? Shouldn't it be R1 and R2?


texts: Over voltage and reverse polarity protection

texts:
I was trying to make an over voltage and reverse polarity protection circuit and create a PCB that I can easily use in some of my projects.
My level of electronics it's not so good, and that's why I'm here.
I thought one circuit, but as long as I know it's not so good:

simulate this circuit – Schematic created using CircuitLab
There's a bunch of circuits arround the internet that involves transistors, but I don't know which one I would pick (or even an IC, as it was discussed previously here, but I couldn't understand which configuration should I use).
Here's my requirements:

It should output around 5V (if the input it's too low it can output less voltage, but if it's greater it should be limited). I want to use it with 74LS ICs, so the input voltage should be 5V, but it can go from 4.75V to 5.25V. The current used it's, at most, 1.5A.
The input voltage can go from +40V to -40V.
I'm using a workbench power supply, so no need to over current protection (it's already integrated).
It should be as simple as possible (~5 components). I don't want to solder >25 components.
I don't care if something blow up. As long as the external circuit stays safe, it's OK for me.

Is there an IC or circuit that suits my needs?
Please go nice on me, this isn't my specialty. Thanks!


texts: What performance requirements are implied by the term "telecom applications"?

texts:
I've noticed the term telecom applications or just telecom in a few datasheets I've come across, and in the book I'm working through, the phrase "In high-speed dc-dc switchers for the telecom market ..." appears.

What kind of requirements does that term imply? Does that mean a device that appears in my mobile phone or perhaps a gigabit router? What's special about those applications in general that one might characterize a particular device or circuit as suitable for it?


texts:
So my problem is I want to build a wireless system with arduino and an RF module.
It is like this one:

But when I tested the module, with this site:

https://www.instructables.com/id/How-to-test-RF-transmitter-and-receiver-before-pro/

my LED is always on, even without transmitter...

What can possibly cause this?

Datasheet for my modules:
https://www.hestore.hu/prod_getfile.php?id=8203

Thanks for the replies


texts: Regarding Radio Frequency (RF) when a Receiver/Antenna Setup can receive DC - What Exactly Does that (DC) Mean?

texts:
I do not have a strong foundation in RF. I have been doing some research but I still do not properly grasp what it means if a receiver/antenna can do DC to X Hz. For example this Funcube Upconverter, http://www.ct1ffu.com/site/hf-converter.pdf, can do from DC to 1700 MHz.

When they say DC do they really mean 0.0 Hz? Or would it be more precise to say 1 MHz for example?

I ask because I am interested in purchasing or assembling an SDR that can do LF (~100kHz) as well as higher frequencies. Obviously there is a big difference between 100kHz and 1MHz and I am wondering what exactly it means when the range goes from DC up to some value.

Is it a hard-value or a vague/fuzzy value/term?

Out of further curiosity, if it's synonymous with 0.0 Hz by don't list a raw number like "0.0" instead of "DC" - is there some other significancy? Is it because it doesn't radiate (i.e. technically it's not RF) - it requires a conductor like a wire?


texts: How are timers adjusted in a micro-controller?

texts: In a 555 Timer the resistors and capacitors determine the frequency and the duration of the timer pulses. How is this actualized in case of a micro-controller timer?


texts: What type of encoder is this (optical, magnetic, inductive... etc)? and how does it operate?

texts:
I have found this circuit mounted to a DC motor. It is probably an encoder but I don't know how it works. I have looked everywhere but I could not find a similar encoder assuming that this is in fact one.
The circuit is placed on a motor casing in a way that does not allow it to rotate or move. The PCB part with green solder mask is facing away from the motor. A metallic disk with a magnetic ring on top of it is attached to the motor shaft facing the green mask and is allowed to rotate freely with the shaft.
The electronic components on the PCB are caps, resistors, dual operational amplifier (IC BA728) and a regular NPN transistor (C3311).
Can someone identify the type of this encoder? or better yet explain how it operates?

(I Modified the schematic again. Thanks, curd.)


texts:
so i have this  crude diy led driver that has 6*680uf 400V caps in the output (im driving a large matrix of leds in series with current limiting on the led side so my board is just feeding ~310-340v dc -depending on the input voltage - to the led matrix)
my problem is that when you cut the power leds with stay lit (very dim) for a long time ,
i was thinking of putting a relay at the output to drain the caps through some resistors but relays capable of switching 400v DC are very expensive  so my question is is there an easy way to drop charged caps voltage to under 30V then pass it to some resistors through the relay?
tl;dr : i want to drain a high capacity 400v cap using some resistors in parallel , to engage the drain circuit i want to use a standard 12Vdc relay (capable of switching max 30v dc) is there an easy way to drop the voltage going through the relay contacts to under 30v from 310-340v dc ?
note : i have the 12v supply to run the relay on board , cap will drain with NC contacts of the relay when power is cut 12v supply of the relay will cut as well therefore engaging NC contacts  ...


texts: Using an Agilent Power supply as an active load

texts:
I have an Aglient power supply Model number N5747A, and I want to use its current sinking ability to become an active load.

This is to test a DC/DC converter (5VDC Output), Gaia MGDS-35-H-C, I want to load the output of the DC/DC to 75% load.

Requirement of Electronic Load
I am using an active load because I need to vary the load from 1% to 100% in 15 steps. An active load will be smoother and more accurate.

According to the datasheet 75% load is around 5.25A. My idea is to hook up the Agilent power supply and set the current limit to 5.25A on the output of the DC/DC converter.

My question is, what kind of "fixed" resistance would I need, would it be just to protect the Agilent supply and DC/DC converter? I assume I would need some kind of power resistor.

The power supply will create a current loop and force the DC/DC converter to draw 75% of its maximum current. Am I correct in my understanding of this?

Below is a drawing for 100% load (7A) on the output of the DC/DC converter

Then the fixed resistance I chose was to maintain a safe operating voltage for the current sink. Example: 60V current source, to maintain 7A's of current through the loop a 4 Ohm resistor will operate the current source in the middle of its operating voltage range of around (28V - 5V )= 23V. If you chose an 8 Ohm resistor for example, then you'll be operating really close to the supply's limits (7A * 8 Ohms = 56V-5=51V). Also the fixed resistor limit in cause the supply goes to 0V (a dead short), so at least 5V/7A = 1 Ohm minimum (rounded up for safety) to put a fixed cap on the current that will flow.


texts: SIM800C - CME ERROR: 15 SIM wrong & CME ERROR: 10 SIM not inserted

texts:
I am making a GSM Tracker with SIM800C module. After deploying it into vehicles.. It works fine.. but after some days, it starts responding as CME ERROR: 15 SIM wrong for command AT+CPIN? & CME ERROR: 10 SIM not inserted for commands required to build TCP Connections. The Commands are written below.

  delay(100);
  myGsm.println("AT+CIPSHUT");
  delay(1000);
  printSerialData();

  myGsm.println("AT+CIPMUX=0");
  delay(2000);
  printSerialData();

also I checked the potential between SIM800C's SIMVCC & GND it was 1.8 V which is fine.
I am not able to understand the cause of the errors.I have attached the Schematic Of device.[![enter image description here][1]][1] somebody, please suggest the solution as it gets disconnected with the server in between the journey & tracker losts.

Edit:- Here are my Some Observations :-

On Soft resetting the Module i.e. by giving AT Command AT+CFUN=1,1, error resolves but I don't want to use this as this is a temporary solution. it starts giving the error again.
There is no effect of hard resetting the MCU.
The error resolves after reinserting the battery but this will not work as  I can't do this from server side.

Please, somebody, tell the cause of the problem so that I can take it as use-case in my development.


texts: Buffer exceeding ramsize do not produce error in avr-gcc

texts:
In my source code I have tried to allocate a huge buffer exceeding the RAMSIZE value (RAM of my component (ATmega324PB) is 2k).

volatile char buffer[4000];

This buffer is in bss section. What I understand is that both data and bss goes to RAM. So it is not possible to do that. But I have no error of avr-gcc (gcc version 5.4.0 (GCC)).

I checked RAMSIZE value in iom324pb.h, but it seems ok.

The error only occurs if I exceed 32767 bytes.

Why not having an error here with a 4000 bytes buffer ?

(NB: compilation and upload works, but not execution).


texts: LM2576 simulation not working at datasheet frequency

texts:
I'm designing a buck converter with TI's LM2576. This is the functional block diagram of the IC, extracted from the the official datasheet

Output node voltage will be a square wave, and inductor current will be a triangular wave. Both waveforms will have the same fundamental frequency, and I understand that this frequency should be equal to the 52 kHz of the internal oscillator used in the comparator.
However, when simulating in LTspice with the model provided by TI, I'm having output waveforms of approx 2 kHz fundamental frequency. Here is the circuit I'm simulating

I'm obtaining this output waveforms. With the readings of the cursors it's seen that the fundamental frequencies are around 2 kHz. A fourier analysis of the waveforms confirms this, and shows that at 52 kHz there is no signal energy, just noise.

Is there something wrong with the simulation? Or am I wrongly assuming that the fundamental frequency at the output is the oscillator frequency?
I need to know this frequency as it is needed for all the components value calculation. I found no application note or datasheet mentioning that these frequencies can be different.


texts:
New here and hoping you can help me out. I've been trying to work on a simple-ish PCB for a work project and need a hand. I'm trying to take one electrical input, and send it to 8 different outputs, once per charge, or once every n seconds. So it would follow one path, then once it is an open circuit, switch to the next and so on. Is such a thing possible?

The intended use is a pyrotechnics firing box. the idea is to take the firing wire (~3V charge,min 1.5V max 5V) and then send it to 1 - 8 firing locations. the firing program would send one firing signal and then after the pyro goes off, that particular firing location would not be a closed circuit anymore.
If we did one that was timed it would be 4,6,8,10,15,or 20 secs(variable if possible) Working on getting the current numbers, will update with it shortly

Amps - 250mA min, 1A max


texts: Choosing between internal oscillator and external crystal- ATXMega32E5

texts:
We are working with a modern microcontroller ATXMega32E5, from the ATMEL XMega family.

Our aim is to use the UART of the controller for effective communication, with the speed of about 9600 or 4800 baud rate. We tested the controller with the internal default 2Mhz clock frequency. UART is working well in both 9600 and 4800 baud rates.

As the controller is working fine, Is it really critical to use an external crystal for the system clock?

We just want to know, whether to use the internal calibrated RC oscillator or any external crystal. Please elaborate the explanation


texts: Li-ion battery maximum discharge current testing

texts: I been playing a lot with Li-ion batteries (NCR18650Bs to be exact) and I have a question regarding how to test their maximum capabilities and generate my own conclusions. If you take a look at this post or their datasheet (http://onvaping.com/battery-safety-and-ohms-law/)  they state that their max continous discharge is about 2C or 6.8Amps. This is fine and dandy but how can test this? I bought one of these (http://www.hobbyking.com/hobbyking/store/__5548__IMAX_B6_50W_5A_Charger_Discharger_1_6_Cells_GENUINE_.html) but it only discharges Li-ion batteries at 1C which is not what I need. Is there a charger like this one that discharges at higher Cs (2C, 3C or more)? If not, how could I approach these tests? Any help is appreciated. Thanks.


texts: Data rate 9600 bps given what is frequency?

texts:
It is said that 9600 bps is the data rate given and if each signal element represents 4 bits then what is frequency?

What I did since each signal element represents 4 bits then in a second (9600/4) 2400 signal elements per second gives a frequency of 2400 Hz.

How frequency is calculated when signal element represents more than 1 bit?


texts:
I am currently working on a little project where I would like to have a display which would have to support this format:

  00 00:00:00

This would have to be used outside on a motorcycle (motocross). Basically it would only be used in sunny weather or only when it's raining very little.
The display would have to be connected to a microcontroller with very little ports (Adafruit Trinket or some sort).
I was thinking about 7- and 8-segmented LED's which would result in a format:

  00 00.00.00

Which would be totally fine. I know there are also prebuilt arrays of these segmented LED's.

Now my question: Would this be the best way to have a clear visible display in the sun light which can withstand some bounces?
If so, how can I make sure that all ports needed (58 = 7+7+7+8+7+8+7+7), fit my few ports?
I have heard about some possibility to need lesser ports and put some component in between, but I have no clue what it is and how it works.

A little note: it should be as low as possible in price (but still be solid and strong);


texts:
I have one NTC thermister from which I want to send the output to two different controllers. Is this possible, or does it affect the accuracy?

To be more specific, my Land Rover has one NTC coolant temperature sender, which is connected to the Water Temperature gauge. I'm adding electric fans, so I also want to send the temperature to the fan controller. Can I simply tap the two wires and connect them to the fan controller without affecting accuracy?


texts:
I'm using jeenodes from jeelabs for capturing data such as temperature, light, humidity and motion. Now I am looking to capture gas and water consumption using reed switches (the meters produce x number of pulses per kWh. How do you suggest I achieve this?

The main questions are:

How should I store the pulse count locally? (EEPROM? I can't simply transmit every time a pulse occurs because some packets might get lost- there might be network outages etc)
How often should I transmit data?
How should I store the pule count centrally? (just the cumulative figure? which I then have to compare to the value at any given time to determine the consumption between 2 dates/times?)


texts: I've been considering using a NANDrive by SST in a new design, however I wasn't sure how complicated it would be to connect a PIC to the ATA interface on the NANDrive. I did a quick Google search and found a couple of forums with people who had done it, but I was wondering if anyone here had experience with it and could suggest a standard software library for PIC C18 that implements ATA.


texts: Replace/refresh 7 segment display of vintage 80's clock radio

texts:
Past two weeks working on this clock radio because I love the looks of it and it is also pretty rare (it must be restored in original condition or better). Fixed almost every non-working feature such as (touch-) knobs, backlight (replaced bulbs with warm-white LED's - awesome result), potentiometers, speaker, ground noise, dirt and dust, casing etc. Arrived in bad shape however after all the effort it turns out to be very promising.

Still one problem left to be perfect, most important part of a clock, the numeric 7 segment display. Very dim, checked the voltages and such, it is just old, aged, the reason why it is dim because it needs to be replaced.

However, unable to find a replacement and searching for another route. Display is a red LED Toshiba TLR4202 (noticed in the service manual of device). Don't know if it is possible to take the display apart and replace the LEDs with some new smd LEDs. Searched on this topic however cannot find anything/anyone done this before. To be sure don't screw up the display before trying because current one is only one I have. Cannot find either a display with same characteristics (same layout) and same size.

Another problem, each LED must fit the old school environment requirements, a LED can only consume 5mA (noticed in the limited datasheet of the display), the MK50366N (no datasheet found) display driver is a MOS IC (needs careful threatment experimenting with this).

Any suggestions what to do, to find a solution to this?

Model

Service manual (TLR4202)

Display layout (TLR4202)

Display Datasheet

This page is the only page available:


texts:
The early Power Mosfets were deemed to be fully enhanced with 10 VDC between gate and source. The gate source threshold voltage was defined for 1mA drain current and would be between 2 and 4 VDC. The gate source rating was 20VDC but the curves showed that there was nothing to be gained by going over 10VDC.

Then logic level Fets arrived for 5VDC systems and then lower to interface with modern logic. The old school analog term called transconductance kept increasing as the on resistance went down every generation.

These days transconductance is not talked about in my neck of the woods because people think it is not important for switching applications. High transconductance and low gate volts are bad for switching when it comes to parasitics and EMC.

Sure the logic level fets do have a place. Some of my best friends use logic level fets. I avoid them because I do not want bad switching.

My question is why cant they make a fet that had a much thicker oxide layer and was fully enhanced at say 20VDC, had a gate source rating of say 40VDC and had a gate source threshold of say 4 to 8 VDC ?

Is their any upper limit of attainable gate voltage rating? Sure the gate capacitance would come down but how would we go on total gate energy?


texts: Relationship of Induction Motor Frequencies

texts: I would like to know how the mechanical rotor frequency [Hz] can be obtained from the electrical stator frequency [Hz]? This is no homework! I have consulted several books as well as the web but could not find an exact relationship expressed as formula. I hope somebody can give advise.


texts:
I have opened a Multimeter (Model:DT830D) and I want to take the input that is fed to the LCD display and display it on my PC instead using the serial monitor of the arduino.

But I am confused about the pins which are responsible for sending the measurement values to the LCD display. Because once I find out which pins/circuit wires are responsible for sending for sending the data, I can very easily feed the same to arduino.


texts: Minimal requirements for a dedicated VNC client

texts:
On many occasions I've considered doing a small hobby project to design a minimal dedicated VNC client, in essence with a goal of a $2 cloud-based computer! (ok $2 is chosen completely arbitrarily).

For those not familiar with VNC, it is a system for sharing the graphical desktop of a remote machine with a local computing resource. There are VNC software clients for Windows, *nix, MAC, iOS, Android etc, etc. Of course there are other desktop sharing systems such as RDP, but lets just consider VNC as its simpler.

There are clearly the following main sub systems

1.Input - PS2 keyboard & mouse
2.Desktop frame decoding
3.Network communciations
4.Frame buffer / Display
I'm ignoring the transmission and decoding of audio, file transfer, printing, etc etc.

My question then is could a simple microcontroller board (e.g. PiC, AVR etc with PS2 connectors, ethernet port and VGA output) handle the throughput of a host desktop with a resolution of 1280x800 and a frame rate of 60 fps? If not, I fancy doing this with dedicated hardware on an FPGA (though I'm unsure how to handle the network traffic), possibly using open source IP from the likes of Opencores.org

Any thoughts would be appreciated! Hopefully my question is suitable for this area of stackexchange, I'm not sure if  superuser.com or servervault would have the experience with microcontrollers to provide insight. However I appreciate my question is slightly open ended. I'll try pad out the throughput spec requirements further when I get a chance.

thanks folks!


texts: Is it better to control an amplitude of audio signal or gain?

texts:
I'm creating simple headphones amplifier with an opamp (basic non-inverting config with RC high-pass on NI) and I wonder, what's better - to control an amplitude of input signal, or a gain of an opamp?

What are benefits from gain control over signal control or vice-versa?
Best regards!


texts: Instantiating Parameterized Modules in SystemVerilog

texts:
In SystemVerilog I would love to instantiate modules like

const int primeArray [11] = '{3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37};

logic clock, reset, increment;
logic [10:0] match;

generate
    genvar n;

    for (n = 0; n < 11; n++)
    begin
        PrimeCounter #(primeArray[n]) counter (.clock, .reset, .increment, .match(match[n]));
    end
endgenerate

Unfortunately primeArray[n] cannot be passed as a parameter, since apparently it is not truly constant. Is there a way to accomplish this? Or am I stuck instantiating

PrimeCounter #(3) counter0(.clock, .reset, .increment, .match(match[0]));
PrimeCounter #(5) counter1(.clock, .reset, .increment, .match(match[1]));
PrimeCounter #(7) counter2(.clock, .reset, .increment, .match(match[2]));
PrimeCounter #(11) counter3(.clock, .reset, .increment, .match(match[3]));
PrimeCounter #(13) counter4(.clock, .reset, .increment, .match(match[4]));
PrimeCounter #(17) counter5(.clock, .reset, .increment, .match(match[5]));
PrimeCounter #(19) counter6(.clock, .reset, .increment, .match(match[6]));
PrimeCounter #(23) counter7(.clock, .reset, .increment, .match(match[7]));
PrimeCounter #(29) counter8(.clock, .reset, .increment, .match(match[8]));
PrimeCounter #(31) counter9(.clock, .reset, .increment, .match(match[9]));
PrimeCounter #(37) counter10(.clock, .reset, .increment, .match(match[10]));

?


texts: What do you use to probe small circuits quickly?

texts:
I still haven't found a really good solution for grabbing tiny surface mount stuff.

Alligator clips are definitely way too big.
Mini-grabbers like this with the spring-loaded hook are an ok solution for bigger stuff, but no good for little surface mount components.  I can solder on little bits of wire and then mini-grab those, but it's tedious and time-consuming. And in my experience they tend to be broken more often than not:

I got some Tektronix KlipChips and some HP 5090-4356 clips on eBay.

The Tektronix clips are hard to open, because the plastic head tips to the side and jams instead of sliding down when you try to squeeze it. The HPs don't have that problem. The Tek pincers are made of wire, so they splay out sideways instead of grabbing well (and get permanently bent, making them jam on each other and not close completely, so connections to thin wires are intermittent).

The HP pincers are made of thin strips of metal, so they are more rigid in that direction. The wire pincers depend on the bendiness of the wire to overlap each other side-by-side (which doesn't work very well) while the HP pincers fold inside each other, with one a little shorter than the other. This seems to work better, but they get bent outward, and the tubes are plastic, so they get bent outwards by any angular stress and no longer close well.

The orientation of the pincers on the HP relative to your fingers is more natural.

These work on SOICs or bigger, but after they've become worn they don't stay on as well. They don't work for surface mount resistors (they just pop off if disturbed even a little) or smaller-pitch ICs.

And I've broken the retractable hook tip for oscilloscope probes by attaching it to a circuit and then letting go, and the weight of the bulky probe and wire put too much stress on the plastic tip and bend it.

Ideally I'd like something that can grip one side of a surface mount resistor, or a pin on a smaller pitch IC, not fall off, not produce any stress on anything, and not break easily.  Any advice, ideas, tips, tricks, ingenious alternatives, cheap Chinese knock-offs of better clips?

(Previously asked on xkcd forums and adafruit forums.)


texts: MOSFET and TVS Voltage requirements for 120V single phase AC circuit

texts:
I am designing a circuit that will gate single phase 120V AC through back-to-back N-channel MOSFETs connected as shown below.  When passing AC, one MOSFET is on and the body diode in the other is forward biased.  The active MOSFET changes for the positive and negative half cycles.  When blocking AC, both MOSFETs are off.

I am considering putting  transient voltage suppression across the drains on the MOSFETs to protect them from breakdown caused by high voltage spikes.  I would use 200V breakdown MOSFETs with a 150V breakdown TVS.

Is using a TVS across the MOSFETs a reasonable design decision?

Are the above component voltages reasonable for a 120V circuit?

Is there any reliability/survivability advantage to using MOSFETs with a drain-source breakdown voltage significantly higher than the TVS breakdown voltage, versus just slightly higher?


texts: Using UPS buzzer as a method of determining AC power

texts:
The only real UPS solution for me where I live is "RCT", a UPS manufactured by a local PC Hardware supplier.

It has a USB port, but I can't find any details about it. I've even contacted the manufacturer specialist via email, but He doesn't seem to like answering potential customers, so I'm hoping that I can get your opinion here.

I want to use the UPS (650VA) to power a Raspberry Pi (2). The Pi will be monitoring freezer temperatures and will email the owners if their temperatures rise above a certain preset value. However, this all means nothing if the Pi looses power because no-one knew that the power was out.

This now becomes a question of "How can I determine whether the AC-in on the UPS is being powered". I've been trying to think of a number of really cheap, yet elegant ways to accomplish this, and the one that I've decided on is, quite unusual and I'm wondering if it's a good idea.

The UPS comes with a standard piezo-buzzer. When the lights go out, the UPS goes into battery-mode and emits a loud beep every few seconds. So I was thinking of linking 2 GPIO ports on the PI to the buzzer in parallel and monitoring it for power. If it's "buzzing", then the power is out and everyone important gets an email letting them know that they need to start making a plan to fix whatever went wrong.

I could even take it a bit further and determine the frequency of the buzzer (not the pitch, but how often the buzzing happens), and when the buzzing is once every second, send another email letting everyone know that the UPS is on it's last legs. (0.2Hz = Battery mode, 1 Hz = very little time left).

Good idea? Bad idea? I look forward to hearing your input.

P.S. Another solution that someone had was to buy a cheap (network) switch and plug it into the Pi (and power it from the mains). The idea behind this would be that when thee power goes out, the network will drop. Fine, but I don't really want to go buy more unnecessary hardware if it can be avoided.

P.P.S I have a spare Raspberry Pi that I'll be using for this. I'm comfortable with Raspbian and it works for what I want to do.

P.P.P.S The UPS I want to get is very cheap. I don't want to make too much of an effort building a custom home-baked UPS system. And I'm not too concerned about the energy efficiency loss because of the DC-AC-DC conversion.

Unlike the question here, My question is whether the solution that I proposed is a feasible one.


texts:
I am fairly inexperienced with electrical engineering and usually just wing small things I.E. a current project.
Basically I have a project box, with a 12v arming switch with a red light in it. Currently I do not have the momentary switch installed but those parts will come in soon.
At the moment I only have the arming switch wired up. It is running off of 2 9v batteries, making the total voltage 18v.
Note I have little technical/book experience as far as understanding electrical work (I.E. do's and don'ts, I don't know the do's and don'ts so.
Basically my question after my ramble is what's happening inside the switch with more than enough volts to function? Is it bad? Is questionable?
I saw a post earlier saying that some devices can go over the voltage on said device a little with some exceptions to sensitive devices.
EDIT @Jyelton Thank you for your feedback. I have corrected the title to something more appropriate. If it isn't to your infinite liking, I can try a few more title ideas.
EDIT @Ignacio Vazquez-Abrams Thank you I will read it.
**EDIT Added photo.
EDIT Thank you Jyelton for pointing me in the right direction. I am not the brightest man. Title changed too "What happens if I supply 18V to a 12V lighted switch?"


texts:
I want to learn about good techniques on how to choose the suitable clock speed for the microcontroller for a project.

For example i want to create a device with a pic16f877 microcontroller that record voice and store it in the memory and then play it out. I don't want to process the signal in order to use a dsp. The audio will have the specs below:

a sampling ratio of 8Khz
16-bit word length
stereo

So if i record 1 minute of sound then i will need 1.8 mb of storage space.  The microcontroller also will connect to a DAC with an SPI serial port. My question is how i could figure out the suitable clock speed that i need. Does the DAC and the SPI protocol determine this speed or the sampling rate of the sound?


texts:
I am making a solar tracker using MG995 servo motors.  The problem I am facing is that as soon as I run the program the servo starts continuously rotating.  Can someone please help me to figure it out?

I am using an Arduino Uno and external power supply for 2 servos.

Below is my code:

#include <Servo.h>
//defining Servos
 Servo servohori;
int servoh = 0;
int servohLimitHigh = 160;
int servohLimitLow = 20;

Servo servoverti;
int servov = 0;
int servovLimitHigh = 160;
int servovLimitLow = 20;
//Assigning LDRs
int ldrtopl = 2; //top left LDR green
int ldrtopr = 1; //top right LDR yellow
int ldrbotl = 3; // bottom left LDR blue
int ldrbotr = 0; // bottom right LDR orange

void setup ()
{
Serial.begin(9600);
servohori.attach(5);
servohori.write(0);
servoverti.attach(6);
servoverti.write(0);
delay(500);
}

void loop()
{
servoh = servohori.read();
servov = servoverti.read();
//capturing analog values of each LDR
int topl = analogRead(ldrtopl);
int topr = analogRead(ldrtopr);
int botl = analogRead(ldrbotl);
int botr = analogRead(ldrbotr);

// calculating average
int avgtop = (topl + topr) / 2; //average of top LDRs
int avgbot = (botl + botr) / 2; //average of bottom LDRs
int avgleft = (topl + botl) / 2; //average of left LDRs
int avgright = (topr + botr) / 2; //average of right LDRs
Serial.print("avgtop = ");
Serial.print(avgtop);
Serial.print("\n");
Serial.print("avgbot = ");
Serial.print(avgbot);
Serial.print("\n");
Serial.print("avgleft = ");
Serial.print(avgleft);
Serial.print("\n");
Serial.print("avgright = ");
Serial.print(avgright);
Serial.print("\n");
delay(500);

 if (avgtop < avgbot)
{
servoverti.write(servov +1);
if (servov > servovLimitHigh)
 {
  servov = servovLimitHigh;
 }
delay(10);
 }
else if (avgbot < avgtop)
{
servoverti.write(servov -1);
if (servov < servovLimitLow)
{
servov = servovLimitLow;
}
delay(10);
}
else
 {
servoverti.write(servov);
 }

if (avgleft > avgright)
{
servohori.write(servoh +1);
if (servoh > servohLimitHigh)
{
servoh = servohLimitHigh;
}
delay(10);
}
else if (avgright > avgleft)
{
servohori.write(servoh -1);
if (servoh < servohLimitLow)
 {
 servoh = servohLimitLow;
 }
delay(10);
 }
else
{
servohori.write(servoh);
}
delay(50);
}


texts:
Xilinx's official DisplayPort IP (seems to be from 3rd party) support HBR2(5.4Gbps) on 7-series and HBR3(8.1Gbps) only on UltraScale.
But GTX tranceivers on Kintex-7 already support 12.5Gbps, is there any physical reason (like physical signal formats) that HBR3 can't be supported by GTX tranceivers? If there is no such reason, then a more advanced (i.e. more parallelization with more resources) IP could get HBR3 on Kintex-7.
There is also the future DP2.0 which supports 10Gbps/13.5Gbps/20Gbps, it is possible to get 10Gbps on Kintex-7 and 13.5Gbps on Kintex UltraScale's GTH tranceivers if there is no physical reasons.
Note: only -2 devices are considered.


texts: Replacing Sukam fusion 3.5kva Mosfet IRF2807

texts:
The mosfets on my Sukam Fusion 3.5kva inverter have blown, I want to replace them.

they have what looks like the following written on them

IRF2807

RP526Y

I can find IRF2807 but not IRF2807 RP526Y, would I need to replace the blown ones with the exact same mosfet?

P.S -This is a home DIY so, I'm not well versed with electronics per se.


texts:
I have the following circuitry:
Battery Supply => Current Monitoring Circuitry => DC Motors

Battery Supply: 4AA NiMH batteries - 4*1.2V (1.5mAh * 4)

Current Monitoring Circuitry: Max 4378 chip (contains 4 current-sense op amps)

I have used the Max 4378 chip for monitoring the energy levels of low-power applications. But now I want to use it to measure the energy consumption of driving two motors. Unfortunately, the chip has a max current supply, Icc, of 2.2mA.

Is there a chip I can use for energy monitoring that doesn't get fried by high currents in the order of 1.5 - 2 Amps? or perhaps an alternate method?

Thank you.


texts: Torque RPM Characteristics of Single Phase Induction Motor within Maxwell's Equations

texts:
A single phase induction motor is constructed of a stator, which contains the stationary main winding, and a rotor, which is a conductive cage which rotates. The stationary main winding is a two pole coil.

The rotor is not a permanent magnet, and it is not connected to the AC supply voltage: it is a brushless motor. However, due to the AC current in the main winding of the stator, an oscillating magnetic field is created, which induces an EMF in the rotor bars, driving a current through the rotor. By Lorentz Force law, a force and thus torque is exerted on the rotor.
I am now attempting to compute the torque in terms of angular speed of the motor.

For low angular speeds this formula is at least qualitatively correct, it is expected that torque is linearly proportional to the angular speed of the rotor, but at the full load torque, the torque no longer varies linearly, but looks like the black line in the image (ignore the red and blue lines for now):

The cause of the torque no longer being linearly proportional to the speed is probably due to losses, and in the literature the rotor is modelled as a secondary winding of a transformer circuit, with the mechanical load on the shaft as resistance, and additional rotor reactance to model flux losses.
My analysis seems to miss out the zero torque near synchronous speed criterion. What phenomenon is responsible for this which I have not included?
My question is: within the context of Maxwell's Equations (physically), how can I calculate these losses using the geometry of the motor?


texts: Need help with eliminating LED-generated noise

texts:
I am very new to electronics, to electronics.SE.com and this is my very first project, so bear with me if my question misses some key-information (in such case, just leave a comment and I will try to add the missing bits).

I have built a device that control about 500 LED's over 106 different channels. Substantially the design is:

1 switched 24V 3A power supply
1 voltage regulator that outputs 5V
1 control board running an AVR ATmega168 (connected to the voltage regulator)
106 LED strings (connected to the 24V power rail)
7 TLC5940 (16 channels each) sink drivers for the LED strings (these sink the remaining of the 24V from the LED's, but their logic is powered from the 5V regulator).

Everything work-ish but I am experiencing heavy problems with noise that sometimes triggers an unexpected reset of my device.

Thanks to a friend that has a DSO, I have been able to investigate the matter and these are my findings...

The noise is on 5V power rail and it is quite big, the overall swing being 2.55V. The SPI channels are all relatively unaffected:

The noise seems to be generated by the LED's, not by the SPI transmitting data (there is no obvious correlation between any of the SPI channels and the noise). In this video (sorry, couldn't find a way to embed it here) you can see that the number of LED's that are ON influence the amplitude of the noise, while their intensity (controlled via PWM) influences the length of the noise "burst" [more details on the video description on youtube].

The frequency of the noise is ~8MHz, which is a frequency I don't use (at least not explicitly), given that my controller board runs at 16MHz and my SPI at 250KHz.

While doing my experiments, I realised that the the DSO picked up the noise even when only the ground terminal of the probe was connected. I interpret this as a sign that the noise is not due to an instability of the 5V feed, but to an oscillating potential of the ground level. Am I right?

Being totally new to electronics and lacking formal knowledge in the field I tried a number of solutions "from the Internet", admittedly without being 100% they made complete sense in my scenario. Amongst others I tried:

to build a low-pass filter using a 1Kohm resistor and a 100nF capacitor and place it on the 5V power rail, but the noise did not changed much in amplitude.
to decouple the 5V rail with a variety of different capacitors including some tantalum ones [various ratings] (no visible effect)
to decouple the ground line (made the DSO go bananas)
to ground the LED's, the TLC board and the DSO to different parts of my circuitry, including as "far back" as possible (i.e. connecting them with separate wires to the ground port of the 24V PSU to avoid ground loops)... but also in this case I had no luck.

It might well be that I did the above in the wrong way (i.e. that the solution is one of the above, but that I implemented it wrong) so - if you feel the solution is one of the above, don't hesitate to tell it, maybe giving me some direction on how to implement it "right".

Final note: because of the physical size of my project, I performed all the tests using only one of my TLC boards that I carefully removed from the rig and used some individual test LED's powered by a 5V source. However less accurate tests on the full rig shows that the behaviour in the "real thing" is consistent with the test readings.

Thanks in advance for your time and support!


texts: How can I safely charge 3 lithium 18650 batteries to use in one pack?

texts:
I'm working on a project to make my own super-bright bike taillight using an emergency flasher LED (something like this:)

The LED package requires a 12V input, but from what I've read from other people who've done this before, it will still work with as little as about 8V. It also uses a 12V momentary charge to switch flash patterns.

I'm planning to use 3 18650 lithium-ion batteries in series to power the light. Each battery is 3.7V, so I should get 11.1 V total, which will (supposedly) be sufficient. I'll put them in a 3-battery holder like this one:

This should be easy enough to set up, but I'm wondering how I should go about charging the batteries. I haven't been able to find 18650 chargers specifically designed for 3 batteries. I've found them for 1, 2, and 4 batteries only. My (limited) understanding of lithium batteries is that all batteries that will be used in a single device should be charged together so that the cells can be balanced, and that if this isn't done, it poses a fire risk. I'd like to avoid having a fire erupt between my legs while barreling down a hill at 30 mph.

Would it be safe to use three 1-battery 18650 chargers, if I charge them all for the same time? Do they actually need to be balanced at all, or am I misunderstanding something? If they do all need to be charged together for safety purposes, then is there any way for me wire it up to get 12V out of 2 or 4 batteries, which I would then be able to charge normally?


texts: How would this circuit work as a white noise generator?

texts:
Got it from an electronics magazine from 1979.

From what I gather, the first transistor's collector and emitter are wired together so it acts as a diode, and the thermal noise from the junction is supposed to be amplified by the two stage common emmiter. I don't really get why the noise would flow through the first capacitor and how would the transistors amplify it, as they seemingly draw all current in the base through the bias resistor and not from the previous stage.


texts: Placement of varistor with respect to fuse

texts:
My design includes a pretty standard AC/DC converter powered by mains for intended use at home. For overvoltage and overcurrent protection, I am planning to use a combination of varistor and fuse placed before the power converter.

I understand it is good practice to put the fuse before the varistor - in an overvoltage event, the varistor will draw a large current that may blow the fuse, protecting the rest of the circuit and even the upstream circuitry.

However, due to extremely tight layout, it is very hard to put the fuse before the varistor.

What risk am I running if I put the varistor before the fuse?

What if I put a second fuse in series with the varistor? Does it negate the varistor's protection of the downstream circuit?


texts:
I have a thermocouple with me which is custom made and its leads are very thin. It has a diameter of 0.19 mm and this has to be soldered to a chip (Max6675). This setup will be placed on a harsh environment. I am stumped on how to deal with the soldering of such thin leads which will withstand the environment.

It would be great if you guys could help me out here. I have added the picture of the thermocouple for reference. One thing is that the length of the leads are 10mm now and not 5mm.

Ther thermocouple will be embedded in an engine valve and the custom PCB will sit on top of the retainer.

So I am looking to connect the thermocouple leads to this PCB for measuring the temperature of the valve. Ofcourse this is the first prototype of this experiment and I will be trying this out in a customized rig and not in the engine itself.

I appreciate all the comments!


texts:
I have an opamp and would like to keep it in class A output. The rule of thumb is 1/2 of quiescent current should not be taken by the load. (to keep it in class A)

The load itself is a R feedback (inverting feedback) going to opamp negative and then a R going to ground

Since I know that no current can flow into opamp inputs (or rather very small) should I calculate this R (feedback) into total load ?


texts: ESP32 (WROOM32) consuming ~77 µA (much too high!) in deep sleep

texts:
I tried to reduce the current consumption of a ESP32 in deep sleep with the ULP enabled. However, the best I can achieve is about ~77 µA of current consumption. I'm using a very minimalistic carrier board (schematic) together with a WROOM32 ESP32-module, which has only 2 pull-up resistors for the 2 needed switches (RESET / GPIO0). I use an external 3.3V-linear regulator and I'm measuring the current that flows out of this regulator.
The program basically starts a ULP program, that has wakeup-period of 1 second set and then goes to deep sleep. The ULP program is 5 instructions long (no loops) and finally calls 'HALT'. So, the ULP should halt almost instantly and wait for the next RTC wakeup after 1 second.
What I've tried so far:

I tried to call rtc_gpio_isolate(GPIO_NUM_12); and rtc_gpio_isolate(GPIO_NUM_15); which did not resolve the issue.
Then I reduced the program to not start the ULP and instead use only RTC-Timer wakeup using esp_sleep_enable_timer_wakeup(1000000*600); before sending it to deep sleep. This did not change anything. So the ULP seemed not to be the issue...

ESP32 High Power Consumption in Deep Sleep Mode


texts: LTC3780 DC-DC 5-32V converter: suddenly fault and hot

texts:
I have planed to build a variable voltage DC power supply based on LTC3780 DC-DC 5-32V converter. I guess you are familiar with the converter, but I am attaching and image for illustration.

I used AC/DC adapter (12V, 4A) on input. Everything worked so I replaced default trimmers with potentiometers. It should have 500k pot on Vout set and 200K pot on current limit set. I tested it and quickly realized that I am getting just 13 V output at max (with 12V input). I did a stupid mistake - I switched the pots, so 500k was on current set and 200k on Vout set.

So I switched the potentiometers as the should be and everything worked fine, for a while... Then I saw green "OK" led is randomly blinking from bright to nearly off (which indicates high and low Vout). I disconnected input, connected it again and realized that red FAULT diode is on and LTC3780 IC is geting REALLY HOT.

I desoldered the potentiometers and replaced them back with original trimmers, just to be sure there is no additional fail with them. But nothing changed - FAULT is still on and IC gets hot in a second.

Is there anything I could inspect to identify the problem, or did I just fry the LTC3780 with using the wrong pots? I will be happy for every suggestion how to possibly fix it, as I already made nice wooden box for it... :(


texts: Understanding type III compensation network for Buck-Boost DC/DC converter

texts:
I'm trying to design a circuit based on Linear Technology's LTC3533 Buck-Boost DC/DC Converter for my own project.
One of the last things I have left to do is to calculate the feedback loop compensation network (datasheet page 14, I need the Vout to be 5 V, so I can't use the stock values from demonstration circuit that's designed for 3.3 V output).
I want to use the type III compensation due to its advantages described in the datasheet. I have calculated the most convenient feedback resistor divider values to be 620 kΩ and 200 kΩ, but I don't understand how this compensation network works and what to do next.
I have found two application notes (first, second) talking about these circuits, but I still can't get it.

What are the poles and zeros of the compensation?  I think they define how the internal op-amp gain curve looks, but:
why is this curve represented by frequencies and why would I want to change it with this compensator?

I know that Linear Technology has this tool called "LTpowerCAD" that presumably would let me calculate the component values for this compensation network easily, but the LTC3533 is not included there and even if it was I still wouldn't understand how this circuit works.


texts: I have little confusion regarding barrier potential (or built-in voltage) and cut-in voltage of diode. Are these are same or what is the difference between built-in voltage and cut-in voltage in diode?


texts: PWM controller to meet EMI/EMC regulations

texts:
I'm designing an application in which the current running into a load is controlled by PWM.
A microcontroller generates a PWM cycle at 20kHz and this signal is used to control a MOSFET which is directly connected to the load. The MOSFET operates at 5V gate logic, while the load absorbs 10A at 100% duty cycle, at 12V DC.
The microcontroller-to-MOSFET signal is carried by a shielded cable of circa 30 cm length, while the MOSFET is placed in direct proximity of the load.
Which is the best way to minimize the EMI in order to comply with electro-magnetic compatibility regulations?
It is important to focus on the microcontroller-to-MOSFET path, which is more likely to act as an antenna, or do I need to worry about the MOSFET-to-load, due to the high current involved?


texts: When does and when doesn't current flow to ground?

texts:
I was thinking about when current can and can't flow to ground. I came up with that current will only flow to ground when we have at least two grounds in the circuit, since then we have a complete circuit and current can flow. I can't however, think of why current will not flow to ground if we only have one ground in the circuit? I would say that it is because the we do not have a closed circuit through which current can flow. But, current, does not need a closed circuit to flow (like with a capacitor). So please can you explain why current does not flow to ground if we only have one ground (or if current does flow to ground if we have only one ground why)?

When I say ground I mean actually physically attached to the earth rather then a conductor (I say this because the earth has so many more electrons that a electrons flowing to/from it would have a negligible effect on the overall number of electrons in it) does this make a difference??

The following circuit is one where I think current should flow to and from ground (sorry for the poor diagram my computer is slow so I can't draw a proper one)


texts: charging an auto battery for a gate opener?

texts: Commercial gate opening systems use solar recharging systems frequently. My location is inappropriate for solar but is right next to a small stream. What properties of a mini hydro generation would be necessary to keep a car battery charged through a dozen cycles per day. ie, wattage, amperage?


texts: Am I calculating battery life expectancy correctly for this RF receiver?

texts:
I have this RF remote/receiver. Though the manual says battery life for the receiver is at least 12 months, I easily get 2 years of operation on a fresh set of batteries.  The receiver 4 uses AAA batteries, so that should be 6V at 1200 mAh. Assuming there are external factors like self-discharging, the battery life is further decreased by 15%.  I'm basing my calculations from this calculator.

Battery Life in years = Battery Capacity in mAh / Current in mAh / 24 / 365 * (1 -.85)

So based upon a 2 year life span (and assuming the .15 constant is correct) is it fair assume that the receiver is drawing on average around 58uA?

I realize I'm making some assumptions here, like the .15 constant.  And I'm fairly sure the receiver is operating in sleep mode and waking up, but I want to make sure I understand this before addressing those assumptions.


texts: What are the safety and device risks associated with not connecting the grounding prong on a 120V AC device?

texts:
For example, imagine a device that comes with a 3-prong (grounded) AC plug. What are the risks associated with, for example, plugging this device into a 2-prong extension cord which effectively disables the grounding as it leaves the grounding prong hanging in mid-air?

I'm interested in both safety risks and device risks.

By a safety risk, I mean a risk to people. E.g., without grounding a short-to-frame could leave externally accessible parts of a device hot with 120V AC.

I'm also interested in device risks. E.g., cases of electrical design where a device would not operate, would operate sub-optimally or with a shorter lifespan that if it were grounded.


texts: multiple power source and diode protection

texts:
I would like to power my DIY led aquarium light with dual power source and looking to protect the revers current in case both the power supply are switch on together. if i use simple diode, which specification should i use.

Both the power supply are 12v5amp, and the load is 15 led of 3 watt each hooked to 5 meannwell LDD700H (3led's to each driver) plus i have 2 12v PC fan's to keep the heatsink cool. i checked the current its around 3.18amp on full load.

As shown in the diagram, what diode should i be using.


texts: Need help with programming an NXTBee on a NXT Lego Mindstorm Robot

texts:
I am doing a project for work using the NXTBee NXT controlled by an arduino. But I'm a novice with programming. I am using ROBOTC and when I compile I am getting an error: Calling procedure 'nxtReadRawHS' with indirect levels mismatch. Parameter: 'unsigned ubyte* pData. Expression: 'incomingData'. Type: 'ubyte'. I know i need a .h library but when i try and put one in from another program it still is wrong. If anyone could help me please help. Thank you

Code starts here:

#pragma platform(NXT)

int power = 0; // Global variable for power.
int steer = 0; // Global variable for steering.
//int direc = 0; // Global variable for direciton.

void setupHighSpeedLink()
{
    // Initialize port S4 to “high speed” mode.
    nxtEnableHSPort();
    nxtSetHSBaudRate(9600);
    nxtHS_Mode = hsMsgModeMaster;
    return;
}

void ReadResponse()
{
    byte BytesRead[3]; // Array we’ll be reading into.
    nxtReadRawHS(BytesRead[0], 3); // Read the array.

    if(BytesRead[0] == '/') { // If we catch the null, read the next three things.
        power = BytesRead[1]-70; // -70 is left, 70 is right
        steer = BytesRead[2]-100; // -100 is Back, 100 is forward
        //direc = BytesRead[3]; // “0? is forward, “1? is reverse.
    }
}


texts:
Having no knowledge of electricals, I am interested in learning the applications of Nichrome.

I understand it has swg ratings. But what I am looking for is a formula that can calculate a particular thing if other certain inputs are provided.

Like the V = I/R triangle, is there a formula for Nichrome containing the following propreties:

Voltage, Amperage, Temperature of Nichrome, Length of Nichrome wire and Rating of Nichrome wire (swg) - I believe these are all the variables applicable, please correct me if I am wrong.

Example 1:
So for instance, if I input the Temperature of the Nichrome I want to achieve, say 50C celius, the length of the Nichrome wire to be 2 Inches and the 32 swg rating, using these, can the formula calculate the voltage and amperage requirements?

Example 2:
Using the inputs, voltage, amperage, length of wire and swg rating, can it calculate the temperature?

Thanks


texts: How to break multi digit number into separate digits in VHDL?

texts:
I found the method for c language.But I do not know how to perform this in VHDL.
Let a fixed point number (12 downto -19) like 3456.478396 I need break this number entirely into separate numbers 3456.478396 --> 3,  4, 5,  6,  (dot) ,  4,  7,  8,  3,  9,  6...  into 11 integer type variables.
How to perform this in VHDL?

signal example : sfixed(4 downto -4);
--'example' contains 9.75 then it is storage as "01001.1100".
--simply example ="10011100".
--10011100 --> integer 156

How to get back original 9.75 number from 156 to separate into single digits?

I USED,

library ieee;
library ieee_proposed;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use ieee_proposed.float_pkg.ALL;
use ieee_proposed.fixed_pkg.ALL;
use ieee_proposed.fixed_float_types.ALL;


texts: What tests for a defective IC may be done with only a multimeter?

texts:
Linked to an earlier post How do I test a circuit without an oscilloscope?

Background :
Inching forward from the previous post I started to do a simple 555 astable with super super long duration  pulse (>30m). An LED was connected which should have flipped state at the end of the pulse.

The LED remained dark; so I connected the LED to the 12V (with the connector on the LED still linked to the rest of the circuit - thoughtless ; I know) to confirm the LED was not defective.

Now the LED glows continuously even after the pulse duration. So I started to think about how to test the 555 now, or any other IC in the future given the only instrument at my disposal is an analogue multimeter

Question :
What tests can be conducted on an IC to determine whether it is defective using only a multimeter? Is it even possible to test an IC standalone without a test-circuit?


texts:
So I understand that the baxandall circuit is a tone control circuit, able to configure a bass and treble through RC filters.

The general understanding I have from it, is that the capacitance of the capacitor can vary resistance depending on the frequency from the equation f = 1/(2piXC).
By using this cutoff frequency you can determine resistors to put in the circuit and direct signal elsewhere.

Note: The circuit in the picture is not a final design, they just have varying values to experiment.

The questions are:

Even though the equation listed above is for a capacitor, RC filters usually have a resistor and a capacitor. I don't understand where the RC combination for low and high on this could be.
Assuming that bass is 200Hz and below and 2.5kHz and above is for treble, how could I change the values for these figures?
I understand that the op-amp is for gain however, is the gain configured by R3 and R2?
Without the op-amp the signal input and output is unchanged, why is that?
The signal output is out of phase by pi, do I need an inverter to correct this phase?

Here is my analysis of the circuit.
Suppose a frequency of 1000Hz, and assume that there is a bass cut i.e X1 is max so 100K. (Using all values in circuit except the pots being 100k)

There are two routes the signal goes through.

Through R1 and R4.
From R1 goes to C2 as the reactance of the capacitor is 3386ohms (1/(2pi*47nF*1000Hz)) which is smaller than the 100k, this then goes to R3 to negative input of op amp.

This is the thought process I have with my analysis, which leads to the questions above. Obviously not all current goes through a single route, but because the resistances are smaller I'm saying that the signal passes through them instead.


texts: DC DC converter simulation time slow in lt spice

texts:
Usually I can 'finagle' DC to DC converter simulations into working in a timely manner, this one has me stumped. I have done the standard gmin/abstol/reltol/cshunt combination, set initial conditions and I still can't get it to simulate more than 3ms before it bogs down and goes to fs/s on simulation time.

How can I get a DC to DC converter to simulate in a timely (us/s simulation time) manner?


texts: OrCAD: Uniqueness/Scope of Net Aliases, Busses, and Net Groups, Hierarchical Ports, and Off-page Connectors

texts:
I am using Allegro/OrCAD Capture. I need some confirmation about the scope of some various types of nets in Allegro/OrCAD Capture, particularly with regards to hierarchical design and projects with multiple schematics, and with multiple pages under each schematic.

There is a distinction here between "schematics" and "pages". Multiple schematics can appear under the same project file. Multiple pages can appear under the same schematic. A schematic can be turned into a hierarchical block which can be placed into another schematic. A page cannot be turned into a hierarchical block, therefore a hierarchical blocks that is placed on a page within a schematic must come from another schematic, not a page within the same schematic.

I would like some things confirmed or answered.

Is a net alias unique only within the page it appears on? (i.e. the
same net alias on different pages will be treated as different nets)

Or is a net alias unique for the entire schematic under which it
appears? (i.e. the same net alias on different pages in the same
schematic are the same net)
Are off-page connectors only unique within the schematic they appear
under? (i.e. they can only connect between pages under the same
schematic, and the same off-page connector name used in two
different schematics are treated as being on different nets)

Or are off-page connectors unique to the entire project? (i.e. all
off-page connectors with the same name under the same project are
treated as the same net.) This possibility seems highly unlikely.
Are hierarchical ports are only unique under the schematic in which
they appear?
How far does the uniqueness of a bus Is it within a page? Or is it
everything under a schematic? Or is it everything in the project?

How far does the uniqueness of a netgroup name extend? Is it only
within a page? Or is it everything under a schematic? Or is it
everything in the project?


texts:
I am using STM32F030F4P6 when I call this Function my ADC starts successfully and I can read ADC value in ADC callback but my MCU hangs at this function line what is the problem? My code is generated by st32mcubemx and my IDE is IAR. I have a problem with this line. My program print "OK1" and ADC run successfully but my MCU doesn't print "OK2".
This is a part of my main code generated by cubeMX:

  /* USER CODE BEGIN 2 */
  uint8_t ret;
  printf("OK1!\r\n");
  ret = HAL_ADC_Start_IT(&hadc);
  if(ret != HAL_OK) printf("ERROR Start ADC\r\n");
  else printf("ADC start sucess!\r\n");
  printf("OK2!\r\n");
  /* USER CODE END 2 */

And this is my ADC init:

/* Includes ------------------------------------------------------------------*/
#include "adc.h"

/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

ADC_HandleTypeDef hadc;

/* ADC init function */
void MX_ADC_Init(void)
{
  ADC_ChannelConfTypeDef sConfig = {0};

  /** Configure the global features of the ADC (Clock, Resolution, Data Alignment and number of conversion)
  */
    hadc.Instance = ADC1;
hadc.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV1;
  hadc.Init.Resolution = ADC_RESOLUTION_12B;
  hadc.Init.DataAlign = ADC_DATAALIGN_RIGHT;
  hadc.Init.ScanConvMode = ADC_SCAN_DIRECTION_FORWARD;
  hadc.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
  hadc.Init.LowPowerAutoWait = DISABLE;
  hadc.Init.LowPowerAutoPowerOff = DISABLE;
  hadc.Init.ContinuousConvMode = ENABLE;
  hadc.Init.DiscontinuousConvMode = DISABLE;
  hadc.Init.ExternalTrigConv = ADC_SOFTWARE_START;
  hadc.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
  hadc.Init.DMAContinuousRequests = DISABLE;
  hadc.Init.Overrun = ADC_OVR_DATA_PRESERVED;
  if (HAL_ADC_Init(&hadc) != HAL_OK)
  {
    Error_Handler();
  }
  /** Configure for the selected ADC regular channel to be converted.
  */
  sConfig.Channel = ADC_CHANNEL_4;
  sConfig.Rank = ADC_RANK_CHANNEL_NUMBER;
  sConfig.SamplingTime = ADC_SAMPLETIME_239CYCLES_5;
  if (HAL_ADC_ConfigChannel(&hadc, &sConfig) != HAL_OK)
  {
    Error_Handler();
  }

}

void HAL_ADC_MspInit(ADC_HandleTypeDef* adcHandle)
{

  GPIO_InitTypeDef GPIO_InitStruct = {0};
  if(adcHandle->Instance==ADC1)
  {
  /* USER CODE BEGIN ADC1_MspInit 0 */

  /* USER CODE END ADC1_MspInit 0 */
    /* ADC1 clock enable */
    __HAL_RCC_ADC1_CLK_ENABLE();

    __HAL_RCC_GPIOA_CLK_ENABLE();
    /**ADC GPIO Configuration
    PA4     ------> ADC_IN4
    */
    GPIO_InitStruct.Pin = GPIO_PIN_4;
    GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

    /* ADC1 interrupt Init */
    HAL_NVIC_SetPriority(ADC1_IRQn, 0, 0);
    HAL_NVIC_EnableIRQ(ADC1_IRQn);
  /* USER CODE BEGIN ADC1_MspInit 1 */

  /* USER CODE END ADC1_MspInit 1 */
  }
}

void HAL_ADC_MspDeInit(ADC_HandleTypeDef* adcHandle)
{

  if(adcHandle->Instance==ADC1)
  {
  /* USER CODE BEGIN ADC1_MspDeInit 0 */

  /* USER CODE END ADC1_MspDeInit 0 */
    /* Peripheral clock disable */
    __HAL_RCC_ADC1_CLK_DISABLE();

    /**ADC GPIO Configuration
    PA4     ------> ADC_IN4
    */
    HAL_GPIO_DeInit(GPIOA, GPIO_PIN_4);

    /* ADC1 interrupt Deinit */
    HAL_NVIC_DisableIRQ(ADC1_IRQn);
  /* USER CODE BEGIN ADC1_MspDeInit 1 */

  /* USER CODE END ADC1_MspDeInit 1 */
  }
}

This is my adc callback:

void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc)
{
  if(hadc->Instance == ADC1)
  {
    adc_val = HAL_ADC_GetValue(hadc);
    Vin = adc_val*0.001;
    printf("ADC val:%d Vin:%f\r\n",adc_val,Vin);
  }
}

And this is my error callback:
At this, I receive ADC ERR:2 means HAL_ADC_ERROR_OVR
I am getting the ADC value in callback but this happen.

void HAL_ADC_ErrorCallback(ADC_HandleTypeDef *hadc)
{
  uint32_t adc_error;
  printf("ADC ERR:%d\r\n",hadc->ErrorCode);
}


texts:
I want to use a BC547 transistor to switch a MOSFET. The base-emitter side should be driven by a Raspberry Pi. The maximum output from the Pi is 3.3V, maximum current is 15mA but I would not like to have more than 6-8mA for safety reasons - output pins are connected directly to the ARM chip and I do not want to risk damaging it.
My problem is that I do not know how to calculate the base-emitter current.
The datasheet of the BC547 says that the base-emitter side is saturated at about \$V_{BE_{sat}}\$ =700mV, but I have no idea about the \$I_{BE}\$. I could measure it with a multimeter, but this question became a theoretical one for me.

How can I calculate the \$I_{BE}\$ for any \$V_{BE}\$ value and any datasheet?
Would it be wise to use a resistor to limit the base current?


texts: C-E leakage current, breakdown voltage in 2N2222A

texts:
I was trying to control the remote start circuit for a generator. The circuit operates on a 12V automotive battery, so it's around 13.5V. The circuit draws around 13mA. I grabbed a 2N2222A and wired up a simple circuit with the generator control inputs on the collector and emitter. With the base at ground, the generator fired up as soon as I connected it across C-E. I didn't expect this.
I went back to the bench and hooked up a 9V battery across the C-E and measured 165mA. Then I read the datasheet more carefully. The max C-E breakdown voltage rating is 40V, but that's at 10mA. I try some more experimentation. Add a 1.5K resistor in series with the 9V battery, for a max 6mA. Now the leakage across C-E is .3mA. Try a 510 ohm resistor (18mA) - leakage has jumped to about 6mA.
What in the datasheet should have warned me that this transistor was unsuitable for this application?
EDIT:
Forget all that about the generator - it's just a distraction where I was attempting to explain why I was trying this experiment.
Just look at this very simple circuit:

With a 1.5K resister, the meter shows about .3mA. With a 500 ohm resistor current jumps to about 6mA.
I tried this with a half dozen transistors from 3 different batches. One batch is claimed to be genuine Fairchild parts. All act pretty much the same.


texts: ±5V using Voltage regulator L7805 and L7905, from DC input

texts:
I am trying to get ±5V using voltage regulator L7805 and L7905.

The datasheet says to use AC source as input and transformer, but I am not really familiar with transformers, and I don't know if I can handle 110V AC as a source.

So I came across YouTube clip, creating ±5V with DC input.

Figure 1: Circuit Diagram

Then I also learned that size of capacitors are enough as long as they are more than what datasheet requires, from searching through StackExchange
How do I decide what capacitor to use in a circuit?

Figure 2: Datasheet from L78xx and L79xx

I choose 220uF, 50V. This was the biggest I have right now.

Figure 3: Test on breadboard and DC adaptor

I used DC 12V as an input.

I tested L7805 and L7905 individually, to check whether they are producing voltage +5V and -5V, respectively.

Figure 4: Individual regulator test

From voltmeter reading, I get that individual operation is fine.

Then I tried the whole circuit diagram (Figure 1), and I don't get the voltage properly.

Figure 5: Whole circuit test

As can be observed from Figure 5, L7905 produce voltage of -5, but L7805 doesn't.
I replaced L7805 with other L7805 to see if that L7805 was damaged, but it wasn't.

I searched more on Stack Exchange, and found one,
Incorrect Output From 7805
but it doesn't solve my problem.

Then I found an website, that suggests I need more input voltage.

I changed to DC adapter of 18.75V with 3.15A as an input, however, it doesn't solve my problem either.

Was it had to do with wrong(?) circuit diagram (Figure 1) from the very beginning?