texts: How to determine relative position using accelerometer and gyro data

texts:
I am designing a robot, and need to track the distance and direction of the robot motion, Nothing in 3D, I only need x,y and angle in x y plane.

My question :

Is it possible to use gyro and accelerometer with kalman filtering or any other methods to
track this? (I do not have motor encoders)

My constraints : I do not have space to include a gps (due to power requirements)
 or motor encoders (due to motor support)


texts: Is there any purpose to source degeneration in a Common Source amplifier with acurrent mirror biasing

texts:
Say you have a cute Common Source amplifier and you have biased it through an NMOS Current Mirror connected to the source.

The current mirror sets \$I_D\$ to a fixed value and consequently, \$V_{GS}\$, meaning the circuit is more stable and won't suffer from \$V_{GS}\$ variations.
Another way to do so is by using a a source degeneration resistor which regulates \$V_{GS}\$ albeit not as well as the current mirror method.
What about combining both? Does that make a difference? Would the circuit be more stable? Is \$R_{SS}\$ redundant at this point?
I've seen the methods presented separately in a few books but I can't find examples of what I did anywhere.
Speaking of redundancy, I've read that \$R_G\$ is there to protect the MOSFET from parasitic currents and more. Is \$R_G\$ even needed in a simulation circuit? Does it serve any other job other than providing protection?
Thank you!


texts: LVDS-SPI bridge, asic or FPGA, and what FPGA

texts:
I'm going to develop a camera utilizing the NanEye 2D image sensor. This has LVDS interface. I'm using a MCU for data processing that does not have LVDS interface, but it  has SPI and I2C. Therefore I was thinking of using a FPGA for a bridge from LVDS-SPI. I want the camera to be battery-powered, so power consumption is a key element in the choice of FPGA to use.

I was wondering if some might have some inputs to what FPGA to use, eventually if it would be wiser to use ASIC. I'm considering using the Microsemi Igloo Nano, the Lattice Mach03 and the Lattice iCE40.


texts: Can't transmit UART signal from Circuit Playground Express to Raspberry Pi witth 433MHz rf link kit

texts:
I'm a noob on electronics and I've been trying to send data from a Circuit Playground Express to a Raspberry Pi with a 433MHz rf link kit.
I followed a Rasperry Pi tutorial with the rpi_rf.py library and worked well. Later tried rewriting the library to include Circuit Playground Express libraries for digital output instead of the Rpi GPIO, however, although I have made various tests to prove the existence of the data, the receiver is not finding any signal from the transmitter.
Is it possible that the Circuit Playground Express is just not capable of doing this? Or am I just not trying the right way?
Thanks in advance.


texts: calculate thermal conductivity for thermal paste

texts:
I'm trying to calculate the thermal paste joint between my pcb and the heatsink

I found in the manufacturers datasheet is has a thermal conductivity of 1.6W/mK ( Watt / meter kelvin ).

Whilst all other data I have for the heatsink is in °C/W. So I could do some reshuffling of the parameters to get (meter Kelvin / Watts) but I am still stuck with this length parameter..

I was thinking in the direction that the paste covers an area. But an area is m^2... So that doesn't remove the dependency on the length parameter...

Added background info: I'm making a big high power LED light. The backside of the PCB will be one plane that has thermal vias to the front side of each lumiled. The dimesions of my pcb are rather large 50cm x 50cm
Regarding the thickness of the paste layer, i suppose not very thick as the pcb will be bolted to the heatsink... or should I foresee some space between the 2 layers?

Can anyone push my mind in the correct direction?


texts:
simulate this circuit – Schematic created using CircuitLab

  What is the smallest value of C that will ensure that the 3dB frequency is not greater than 100Hz?

That is the question from the book but my question is not that exactly.

I am trying to find the cutoff frequency which is of course a step toward the solution and I have the transfer function:

$$\frac{sC_1R_2}{sC_1(R_1+R_2)+1}$$

now somehow the book goes straight from the transfer function to

$$\omega_0 = \frac{1}{C_1(R_1+R_2)}$$

I am having trouble understanding how we found \$\omega_0\$.


texts: How can electrons flow through superconductive material

texts: I am a little confused. Metals has enormous number of free electrons but low carrier mobility. It means that electrons are moving slowly but large amount simultaneously. Lets say you pass current through wire and measure voltage diference on it. Then if you divide this voltage by wire length you get electric field. It will be small because voltage drop is small but it will be right amount for moving your current. And now lets cool down a wire for temperature near 0K. The metal will become superconductive. So you can't measure voltage difference because the resistance is 0 ohm, hence you have zero electric field so how can electrons flow through?


texts: How is the propagation delay of a logic gate affected by the amount of inputs (fan in)?

texts:
I was trying to find out what parameters affects propagation delay and how.
When trying to discover if somehow the propagation delay could increase with the increment in the amount of inputs in a gate, I found this paragraph in section 5.7.1 of INTRODUCTION TO DIGITAL SYSTEMS by Mouhammed Ferdjallah:

  "The fan-in is the number of inputs of a logic gate. For examples, a two-input AND gate has a fan-in of 2 and a three-input NAND gate has a fan-in of 3. (...) If the number of inputs is increased, the parasitic capacitance and thus the propagation delay is increased and the noise margin is lowered. Normally, the propagation delay increases as a quadratic function of the fan-in."

I'm trying to:

Find other sources that confirm that the number of inputs in a logic gate increases its propagation delay following a quadratic function.
Understand why do the parasitic capacitance increase. In a CMOS NAND gate, no matter how many inputs you have, each input drives only two transistors, one PMOS and one NMOS (in the book this section is just after the "CMOS Logic Networks" section).


texts: How to bias MOSFET for finding S-Parameter simulation?

texts:
I wanted to use a BSIM4 model of NMOS in my circuit. I got the correct dc biasing point, certain VDS,VGS and IC. But I am having issues measuring S-parameter data for MOSFET amplifiers. I simulated circuits in BJT and it works fine. Is there any generic circuit for MOSFET? I am not sure where to put up the DC block and RF feed with proper biasing in MOSFET (NMOS)so that S-parameter data could be measured. I ended up with the circuit shown below, it has invalid data for S-paramters if measured. Any suggestion/correction in the circuitry will be very much helpful.

I am getting the S21 (dB) is below, which is invalid:

My bias points are VDS=0.5V, VGS=0.8V, IDS=45.48uA and supply VDD=1.2V. Hence I got RDS(which is R1)=15.39kohms.


texts: built in charge controllers take amps they need?

texts:
Many devices have built in charge controllers that stop charging when battery is at 100%.  I read several places that you can charge devices with the manufacturers recommended voltage and that higher amperage sources will not hurt as the device will take what it needs. True?

Given this, why do portable lithium battery packs (for example a 240WH Lithium pack I know charges at around 40Watts) recommend charging sources be of a limited Wattage? For example if the battery pack has a 12v 3a charge port, any reason I can't plug in a 12v 19a source?  Same question regarding a 12v 3a fan, any reason I can't plug in a 12v 9a source?

UPDATE:  Part of the reason why I am asking is that I am trying to find a way to charge a 240 WH Lithium power pack with a 200w 18v 11a (max/ideal) solar panel without using another battery.  I thought If I just stepped down 18v to 12v with a dc-dc regulator that would be good enough.  The manufacture just keeps saying, no more than 100w solar panel.

I guess I need clarity on these NOOB questions:

**(1) Why does the amperage of the power source matter if batteries have a high amperage capacity
      (2) How do charge cables limit amperage  and can this be directly implemented from a solar panel?      (3) is there difference in the way battery sources and solar panel sources make available or push power?

I know this is not a typical solar setup.. i'm just looking to leverage a big panel during solar hours without a battery bank
These are the products:

My Solar panel is 200w 18v 11a.  CHAFON 200Wh Portable Generator Power Station Rechargeable  (but want to consider other like Jackery 240).  MaxxAir 4401K 4 speed 12v 4a fan. Alpicool C15 12/24v 50watt Freezer. Nextrox DC/DC Converter Regulator 24V Step Down To 12V 20A

Trying to find a way to run and charge these ONLY during solar hours directly (without tying my battery and trusting Low Voltage Disconnects).  The freezer supports 12v and 24v.  One person at Chafon said no more than 22v, another said no more than 100w input.

I read the duplicate question/answers and it only seems to confirm my suspicion that more amperage availble in the source should not hurt my devices.. but I am still puzzled why manufactures state a limit the input wattage?  I understand the Just do what the manufactures says to do and that would be safe I guess but also really complicates the solar panel setup.

**

**UPDATE: Thank you for comments. somebody on another forum confirmed the Chafon 200wh BATTERY PACK could charge directly from a 12v battery which of course has a lot more watts than the recommended unless fused . For my own understanding and to rephrase the question, what's the difference between power from a 12v battery vs power from a 200 watt (18v 11a) solar panel that has been reduced to 12v.  Is the issue that a solar panel is pushing/forcing power where as a battery is offering stable/waiting power ?  And how does this apply to a 12v device wanting to charge at 40watts vs a fan that operates at 40watts **


texts:
For my project I need voltage of 2 li-ion batteries in series. For charging them I would use this charger (one for each battery):

Could I connect those two chargers (with one battery on each charger) in series and plug them on 9/12V adapter? Or should I use 5V voltage regulator on each charger?

Another possibility would be to use 7.4V charger like this one.

I would use two identical batteries so I think batteries couldn't get unbalanced.

EDIT:

Could I use protection board in second link and a 8.4V adapter like this one?

Would 9V adapter be ok?


texts: get the failed step name from KIKUSUI TOS9200/TOS9201

texts:
I'm using the KIKUSUI TOS9200/TOS9201 HIPOT tester, by setting a program number.
If a step in the program fails, I use the MON command get the step monitor values.
The information I need is in the step NAME. How can I get the failed step name?


texts:
I'm designing a PCB for charging single-cell Li-ion batteries via USB. Hereby, charging via USB from a computer and from a wall adapter should be supported. As a charger IC, I consider using the following part:
https://www.ti.com/lit/ds/symlink/bq25606.pdf?HQS=dis-mous-null-mousermode-dsf-pf-null-wwe&DCM=yes&ref_url=https%3A%2F%2Feu.mouser.com%2F&distId=26
The charger IC automatically detects via the D+ / D- singals which kind of wall adapter is connected or if a computer is connected and limits the charging current accordingly. The screenshot below shows the different cases.

I wonder why the case of USB100 (a limit of 100 mA) is missing. I thought old USB ports from computers may only be able to supply 100 mA. Wouldn't it pose a risk using this charger IC if one would connect it to a USB port than can only supply 100 mA?


texts: Is it possible to carry RS232 signals over a USB cable?

texts: Is it possible to carry RS232 signals (115200 baud rate) over a USB cable? I don't want to use FTDI's RS232-USB converters. I just want to carry TXD, RXD and GND signals over a USB cable. Are my signals affected from external noise badly?


texts:
Let's consider this device I have built: It is essentially a power supply for a 24V DC motor. The power supply is switched on and off according to a proper control signal (which drives a relay) which is not important at the moment since it has always been put to ON while the device was working.

Let's focus on the final part of the circuit, with the motor, the fuse of 10A and the transistor BUV20.
The motor should require an average current of 8A at 24V and BUV20 can provide 50A. BUV20 is cooled through a fan (shown at left in the picture) and a metal heatsink (with thermal paste.) The motor's nominal voltage is 24V, but I have inserted a potentiometer in order to decide its value (generally I will use a voltage between 17-20 V since I do not need its maximum speed.)
The device was working at these values of voltage, then it suddenly started to rotate at an exaggerated speed. Then, the 10A fuse stopped it after some seconds. (Maybe since it is a delay fuse.)
After this event, I checked the fuse of 10A and it is broken. Then I have measured the collector - emitter resistance of BUV20, and I have seen it is 0.
So, my opinion is that BUV20 has broken while it was working, and its collector and emitter terminals shorted. So, 27Vpeak were provided to the motor, which started to run at exaggerated speed.
What might be the cause of this transistor problem? I may change it with another BUV20, but I think its accident may not be casual, and there may be a design problem. So, what may be the cause of collector and emitter short while the transistor is working? A motor spike, a transistor defect etc. Do you have any advice?
UPDATE:

Under your great advises, I have done the following modifications in my circuit (in red), with also other additional elements I have put by myself:

A 100nF CAPACITOR on the biasing network of BDX53C, to avoid fast variations of the biasing voltage when moving the potentiometer.

The original delayed fuse of 10A has been replaced by an INSTANT FUSE OF 10A. This because the delayed fuse has burnt only after some seconds, and that time has been enough to break the transistor.

A REVERSE DIODE has been put in parallel to Base-Emitter Junction of the BUV20.

A ZENER DIODE OF 24V, 5W has been put in parallel to the motor. This is not a complete protection, but follows this logic: if BUV20 breaks and collector and emitter become shortened (as happened the last time), the zener diode puts on the motor only 24V, and not potentially 27Vpeak of the collector voltage. This zener will not survive a lot in this condition, but it gives time to the other protection systems for activating (note that 24V is the maximum voltage of my motor, so in this time the motor will be safe).

A COMPARATOR which detects a short between collector and emitter of BUV20 due to its break.I have designed the resistors so that, if the emitter voltage will be over 23V (it should not happen in my operation conditions), the comparator output will become low and a digital logic (precisely, an arduino system) will switch off the relay that supplies the BDX53C.

What do you think about these measurements? Should I modify them or insert other protections?
My main aims are, in decreasing order of priority:

protecting the motor
protecting the BUV20
protecting other elements


texts:
I'm a beginner at PCB design.
We've subcontracted routing for a PCB; it contains mixed analog and digital signals and it's a 4-layer PCB with an inner split GND plane (Signal - GND - VCC - Signal).
They delivered it to us and I've got some questions about how they designed the GND, because it's not what I'm used to seeing. For example:

Inside zone "1" :

I don't really understand why they put tracks rather than make a copper pour? Is it a good practice to minimize crosstalk and have a better return path?
Don't know why there are two GND vias lost between the 2V5 and 3V3 pins, just linked to the inner plane (no copper pour at top nor bottom).

Inside zone "2" :

Again, I don't understand why they made two different copper pours for capacitors and a bigger one at the bottom, just linked to the bottom and inner layers. Is it better than just making one big copper pour with the 2 GND pads of the capacitors?

Is thier anything wrong with my pcb?


texts:
Hi,

What is the Part number of this component?

Top mark : S0 N

Analog Devices

Do you have any idea?

Thank you.


texts: STM32F429I Discovery board - unable to do printf() redirection using SWV/ITM

texts:
I am an STM32 newcomer. I recently got an STM32F429 Discovery dev board which I have been playing around with. Currently I'm trying to figure out how to use the debugging functions of this M4 Cortex, specifically the SWV ones.

I used STM32CubeMX standalone to generate a project for Atollic TrueStudio and then modified the main.c files infinite loop as follows to blink an LED on and off every 2 seconds and to printf a message to the console.

  while (1)
  {
     HAL_GPIO_TogglePin(GPIOG,GPIO_PIN_13);
     HAL_Delay(2000);
     printf("hello");
  }

When I run debug it programs the board perfectly. I see the LED blink on and off. I followed the steps in this article which explains how to setup printf redirect to the console by generating a syscalls.c file and making some changes to the int _write function in that file. I am however struggling to get this to work. When I step through my code and get to that printf("hello") line it just skips over it like it doesn't exist and there is nothing printed to the SWV console.

Below is a picture of my debug settings and the modified version of int _write which resides in my syscalls.c file.

int _write(int32_t file, uint8_t *ptr, int32_t len)
{
   int i=0;
     for(i=0 ; i<len ; i++)
       ITM_SendChar((*ptr++));
     return len;

   errno = ENOSYS;
   return -1;
}

Is it possible I've missed something in the setup when using CubeMX? I followed Atollics recommended setup for printf redirect exactly but nothing shows up in the SWV console.


texts: How to connect two circuits into on light bulb with a switch in each

texts:
I am not an expert. but I have two circuits, each on is 220v and both have a switch. I want to connect the two circuits into one light bulb. what I have to follow or need to know, To make this happens?

if any one of the switch turned on, the bulb goes on. and doesn't goes off, until all switches is off.

UPDATE

THIS DIGARM IS JUST FOR CLARIFICATION NOT FOR ACTUALLY USE.

I did this to clarify what I mean. what I need to adjust to make this happen. I don't mind major editing.

simulate this circuit – Schematic created using CircuitLab


texts: How to get USB-mouse output from capacitive touch panel?

texts:
I have this 7" capacitive touch panel overlay that I want to attach to my Raspberry Pi 4B.
I don't know what kind of data comes out of that FPC cable, or even what its pinout is. Is there a well-known standard?
How can I convert the signal from the touch panel to mouse-like signals (attached as USB device)?
I found out that AR1100 (Adafruit's) works well for resistive touch screens, but I am not sure that IC will work here.
Searching for capacitive controller doesn't yield good results. I only get touch button controllers i.e. like many in Cypress CY8C* series and not a controller for real touch screen panel. I don't even know what search term to use.
Please advise.


texts: Is it possible to predict the operating state of a power system (using MATLAB) if I have calculated the voltages at all nodes by state estimation?

texts:
If I have calculated all the node voltages by state estimation, is it possible to predict which operating state my system is at? By operating state, I mean any of the following:

In addition to being able to say which operating state my system is at currently, I want my code to be able to say if there is a risk of heading towards an emergency or 'in extremis' state. I know my question should've been clearer, but I don't know enough at the moment. It would be great if someone could suggest an algorithm and the data I would need to execute the algorithm.


texts: How does PCB traces length effects parasitic capacitance on the board

texts: How does length of trace effects parasitic properties of the PCB board?  Is it longer the length, higher the parasitic?


texts: Setting up data prior to a rising edge - what's best practice?

texts:
I'm a newbie, playing around with a very simple single port block RAM (on an FPGA actually).

Its 'read'-timing is standard stuff -

i) An address on the RAM input gets latched on a first rising clock edge (call this edge 'one').

ii) Data stored at this address then appears on the ram output on the next rising edge ('two')

Now, obviously for step 'i' I need to make sure my address is set up and stable before (and for a hold-time after) rising edge 'one'.

My simple question is: what is normal practice for when to do this?

I could set up the address a full rising edge (edge 'zero') before its needed for latching at edge 'one' - but somehow this feels inefficient as it seems I'm taking at least 3 rising edges to get data out of my RAM.

Alternatively I could set up my addresses on the falling edge of clock, immediately prior to it being needed at rising edge 'one'. But I've read that using both rising and falling clocks in designs is also not an entirely typical approach.

What's best? Have I misunderstood something basic?


texts: What's the dual of Faraday's law of induction?

texts:
Faraday's law of induction tells us that if we subject a coil to a changing magnetic field, a voltage will be found across the coil.

Duality suggests something similar should exist for capacitors: if they are subjected to a changing electric field, a current will be found.

Does this phenomenon exist? What's it called? Is there a simple experimental apparatus one might construct to observe it?


texts: How do loose connections cause overheating, arcing and start a fires?

texts:
I am confused as to how a conductor can became overheated when it's connection to the circuit is unintentionally loosened.

A loose connection will cause the resistance to increase and decrease the current. Why does the temperature increase if the current decreases? Is my understanding wrong?

I have a hypothesis that is it because of the reduction in the contacting surface area that causes a potential difference at the surface. Since there is a voltage drop across the contacting surface it will seem like a load to the power source and will consume power. Which means that it will transform electrical energy to heat energy. Am I right?

I understand why an arc is produced at the moment when a connection is opened. It is because of the ionization of air particle by the large electric-field when the resistance is not high enough to break the circuit. My question is whether this arc will produce heat or not? If yes, then why? Is it because of the ionization process itself? How does this process take place?

I am weak in atomic theory, can anyone explain to me the energy flow when ionization occurs?


texts: Is it possible that the line frequency can change along the distribution network?

texts:
We use single-phase 220-230V~/50Hz here in Turkey. The line frequency may vary ±5%.
One of my colleagues told me that he measured the line frequency in a factory (probably a customer's factory that we sold electricity meters) as 70Hz.
I have nearly basic knowledge of electricity generators and distribution networks, but I think most of them could have identical (or nearly identical) specifications/properties. I know the line voltage can jump up to 240V or even 250V. But, how can the line frequency change? What can cause this?


texts: What kind of components in a computer power supply can explode loudly?

texts:
Today I heard a loud bang that tripped the circuit breaker in my server room. It must have been really loud because I could hear it 2 rooms away through 2 heavy doors and it was like a firecracker going off right next to me.

Long story short, it narrowed it down to one PSU from one of the computers. It smelled like burnt rubber and was really hot even after ~40 mins of being turned off when I finally got to testing it. All the rest of the tech was thankfully fine.

Its an old server PSU, like 10+ years old so not really surprised it blew up. Its a 800W unit made by HP but I couldn't find any model identification on it.

The weird thing is, I opened it up to really make sure this is the thing that failed but on the inside, it looks totally fine. Tested the fuse - all good, all the caps look good, no charring anywhere. After around 10 mins of looking inside the burning smell had faded away too. Still though, its the only thing that won't turn on. I got the rest of the computer it was attached to back up and running with a replacement PSU.

At this point I'm just curious - what could possibly create such a bang and not leave a trace afterwards?


texts: Which is the best way to ground the top layer copper pour on a PCB?

texts:
I'm currently designing my first PCB, and having done some reading, I understand that the copper pour on the top layer should be grounded as it otherwise just creates a giant antenna.

What would be the best way to connect it to the ground plane on a 4 layer board? Is a simple via enough, or would that be too small (or would multiple vias be required)?


texts: Is there a difference between a tempco resistor and a thermistor?

texts: That is, other than just the nomenclature.


texts: A question on precise resistor measurement for current loops

texts:
For a current outputting device I’m using a data acquisition board which can only measure voltages.

To translate the currents to voltages I use similar to the following shunt resistor:
http://docs-europe.electrocomponents.com/webdocs/13ec/0900766b813ecc53.pdf

These types of ultra-high precisions are used for 4-20mA current loops. In the data sheet the tolerance is mentioned as ± 0.005%. It means I can trust that this resistor R is such that 499.975 < R < 500.025 ohm.

So far so good… To prove and document the resistor’s resistance value, I’m using a calibrated current test device which has a certificate for 4mA and 20mA nominal currents. According to the certificate of this current regulator device, for 4mA mode the calibration institute measured 4.0055mA ; and for 20mA mode measured 20.0072mA.

I apply current across the resistor with this trusted current tester at 4.0055mA and 20.0072mA and I read voltages as 0.990V and 4.995V in order with the data acquisition board. This means I obtain resistances as 247.12930 ohm and 249.67509 ohm.

The data sheet of the ultra-high resistor claims its tolerance is ± 0.005%. It means R is such that  499.975 < R < 500.025 ohm but I’m measuring 247.12930 ohm and 249.67509 ohm at different currents which are both less than the data sheet claim.

The current tester claims the uncertainty is ±0.00040mA at 4mA mode and ±0.0035mA at 20mA mode.

Either the regulator is not regulating well or the data sheet is wrong. But both the current regulator and resistor have certificates. Should I trust the resistor data sheet or calculated resistor value from my measurements?


texts:
I am designing a PCB with analog signals for the first time, and I would really appreciate any feedback on my layout and routing.

The circuit is a light-meter, consisting of a photodiode connected to a transimpedance amplifier which connects to an ADC.

I simulated the transimpedance amplifier and put it on a breadboard, and it worked, but I am nervous about moving to a PCB. I based my layout on a TI reference design (http://www.ti.com/lit/ug/tidu535/tidu535.pdf), with a keepout on the top and bottom planes. I tried to make the amplifier output as close to the ADC pin (pin 16) as possible, and I tried to set up pin 18 as the single ground connection to my analog corner. Can you think of anything I could do differently?

The top layer of the transimpedance/analog section:

The bottom layer of the transimpedance/analog section:

The relevant portion of the schematic:

Note: my transimpedance amplifier seems to be stable without a feedback capacitor. I think it's because my op-amp has a GBWP of just 6kHz and my large-area photodiode has a capacitance of 1nF. It has worked in simulation and on a breadboard and has a stable output with feedback capacitors between 0-100pF.

Edit: added links to the datasheets.


texts: How to supply a negative voltage from a simple battery or psu?

texts: I am using an op amp (741). I need to supply its pin 4 with -5 volts using a power supply unit from a computer or from a simple battery. How am I going to do that?


texts: Is it possible to write to serial terminal program via JTAG interface?

texts: I have a CC430F5137 wireless development kit from Texas Instruments that I program via a JTAG interface, MSP-FET430UIF. On the computer side, the JTAG interface is connected to a USB port. Is it possible, for debugging purposes, to write to a serial terminal program via the JTAG interface?


texts: MIDI Output circuit not being recognised by MIDI devices

texts:
I'm trying to make a MIDI Out circuit from the Sparkfun web page (https://learn.sparkfun.com/tutorials/midi-tutorial/all). My MicroController is a 3v3 device but I'm using two Not Gates as used in the sparkfun circuit, which are powered by a 5V rail.
Because I'm having difficulty with the generated output I created a MIDI input circuit to measure the voltages in an Oscilloscope. I'm not actually powering the MIDI input circuit I'm just using the standard input resistance, 220 Ohms, a diode and Optocoupler so that I can measure what's happening.
So that's my two circuits, my problem is that my MIDI Output circuit is not being recognised by either of my synths. I decided that I must be transmitting the wrong signal, hence my test MIDI Input circuit to measure voltages.
So for comparison I plugged a MIDI Controller Keyboard into my MIDI Input circuit and measured the resulting voltages, when I pressed a key. As a second example I used a Sequencer with a MIDI Output and send a Note On message to my MIDI Input circuit and measure that on the scope. Finally I tried the SparcFun circuit with two Not gates which I'd created. All three look exactly the same to me, well there are differences in the third byte, the attack parameter of the note on message.
So the tree waveforms I'm getting MIDI Controller, MIDI Sequencer and My MIDI Output based on SparcFun circuit:

So looking at those three outputs I'm struggling to understand why my output isn't being accepted or recognised by my MIDI Devices. The only thing I can think is that I'm not pushing enough current, but I'm powering my circuit off a bench top power supply pushing 9Volts into a 7805 Linear 5V which is creating the 5V Rail. In all cases the voltage is measured across the 220Ohm resistor in series with the input of an Optocoupler, so the Voltage drop across the input Optocoupler should be the same in three cases so the current through the 220 Ohm resistor should be the same in all three cases.
Be very grateful for any assistance or pointers, as to what's going on.


texts:
I'm not able to obtain an adapter from local markets for vga to composite video output. Found a circuit [VGA to composite circuit. Does it work?] that claims to work. I didn't had a vga cable so  I inserted jumpers into the port and created the circuit in breadboard then to rca composite cable. I found flickering screen when connected to tv but not a greyscale output of my screen, it doesn't detect source.

Why didn't it work? Is it because I must use vga cable instead of jumpers? How to make it work? I also found active adapters that takes external power source.[https://www.amazon.com/StarTech-com-Resolution-Composite-S-Video-Converter/dp/B001NXDQEK] Do I need one of them?

(I have an old crt samsung tv that has video, audio & rf input ports only that I want to use as a external display for my laptop
whose lcd screen is damaged.)


texts: Do you always need a GPIO expansion chip when using i2c?

texts:
SUMMARY:

I'm trying to learn the basics of understanding how to wire up a simple circuit using the i2c. I'm wanting to build just a simple project involving an LED and a push button with my raspberry pi. From what I understand the "pi" already is i2c capable and i2c isn't a piece of hardware it's just a protocol from what I understand.

However, I thought initially all I had to do was wire up the push button and LED to the SDA and SCL pins on the pinouts of the "pi" and I would be good. But apparently I need an expansion chip or some similar device that provides instruction and registering for devices like the LED and PushButton.

QUESTION_1:

Do I need a GPIO expansion chip to connect to my "pi" before I can start hooking up devices using the i2c functionality?

I already ordered a 579-MCP3008-I/P and a 579-MCP23017-E/SP in case I have to. I'm unsure on what the I/P or E/SP means but I was told the MCP3008 and the MCP23017 were good ones to get.

QUESTION_2:

From my research here and through examining the circuit diagram below I thought the (SLAVE) devices were my LED and Push Button and then my (MASTER) device was my "pi". I going to assume that my pi is my MASTER device but my SLAVE device would be considered my expansion chip NOT the LED or PushButton.

Therefore, my LED and Push Button isn't a slave or a master device it's just an extension of the SLAVE DEVICE being the expansion chip. Do I have this right.

I drew out my conclusion of what i'm understanding. Forgive my drawing as I know it's not to scale. Can someone critique me on whether or not i'm understanding this setup and terminology when it comes to slave and master.


texts:
I'm looking at the following two d-type flip flops to create a toggle for the EN pin on another IC.
I was going to feed Q back into D with an inverter such that it is toggled when clocked ( would this need a delay to not violate the hold time on D?)
https://assets.nexperia.com/documents/data-sheet/74AHC_AHCT1G79.pdf
https://assets.nexperia.com/documents/data-sheet/74LVC1G175.pdf
My question is what the default state is when these power on. There is no mention in the datasheets. The second has a reset line so presumably I could have an RC delay on that so that VCC is fully risen before the reset goes high - but I am not sure if this is necessary, and in any case the first does not have a reset line, so does it expect/require an initial clock pulse to put it in a known state.
On a side question, as these are edge triggered, will it matter if the clock stays high for a long (1-2s) duration?
If there is a better (cheap) option to do this that would also be great.


texts: Since the z-transform of the zero order hold is 1, why bother including it in analysis or simulation?

texts:
The \$z\$-transform of the zero order hold is 1. So why should it even be considered in the discrete time analysis or simulation of discrete time control systems?

$$Z\left(\frac{1-e^{-sT}}s\right)=\frac{z}{z-1}-z^{-1}\frac{z}{z-1}=1$$


texts: Infinite loop on microcontroller vs modern CPU

texts:
On a microcontroller (more specifically, on an Arduino Uno board using the ATmega 328P microcontroller) I would normally use an infinite loop to check for inputs etc (in Arduino land, this is normally the loop() function). If I leave this function blank however, it doesn't cause any problems.

On a desktop / laptop with an Intel i7 CPU etc if I ran a similar infinite loop (with nothing to do, or very little to do) it would pin the CPU at ~100% and generally spin up the fans etc ( a delay could be added to prevent this for example).

Why is this seemingly ok on a microcontroller but not usually wanted on a microprocessor? Am I right in thinking that the ATmega is in fact running at 100%, and that because it is so low powered it doesn't cause any obvious heat problems?


texts: Can anyone solve with this circuit the problem is with resistor in series with diode?

texts:
Can anyone solve this problem ??
I want vout analysis

The output is in green ?
Why the capacitor voltage is -10 from vout to node above vin ?? In first negative cycle the current will move anticlock wise so it was supposed that capacitor has +ve 10 charge from right while in reality havent been ?


texts: Step Generator Reset Circuit Alternatives

texts:
I'm working (slowly) on a project to build a curve tracer based largely on the Heathkit original (Heathkit Catelogue - IT-1121) and I've come up against an issue in the step generating circuit.

The issue is with the step reset logic which produces a spike at the end of the selected sequence of steps.  It took me a while to twig what the issue was, but the basis of the design is that the reset circuit "sees" the next step before the reset is triggered.  The consequence of this is that the smallest spike of the n+1 step is produced at the output.

Clearly I can't have these spikes messing up my DUT base/gate signal and I'm assuming this issue existed in the original. To my annoyance, I missed this at the breadboard stage (I did notice the spikes, but I put it down to stray inductance).  Right now I'm thinking I should re-build the section completely, most likely using a microprocessor.  But, before I (reluctantly) abandon this board, can anyone suggest an alteration that would remove the spikes?  One thought I had was to reset using the NOR gate pulses - so instead of looking at the output, I count the input pulses and reset on the rising edge (given that the counter IC increments on the falling edge).

Note: careful observers will notice that I've altered the reset circuit slightly to avoid having to use the (impossible to obtain 7M5 POT), but I'm pretty sure the update retains the original idea.


texts: How can I convert from 12v serial to 5v serial?

texts:
I am attempting to recreate the project detailed here: http://amiga.robsmithdev.co.uk/instructions .

The important part is that a USB FTDI adaptor with the CTS pin broken out is required, and that adaptor will be connected directly to an Arduino. Problem: I don't have such an adaptor. I do, however, have a normal hardware serial port on my computer.

From what I understand, there is nothing stopping me from using this serial port in place of the specced FTDI adaptor, aside from the differing serial signal levels (my computer is likely to have +/-12v, whereas the Arduino is expecting +/-5v.)

So, how can I convert the signal level while maintaining signal integrity at a high serial baudrate (2mbaud is required)?


texts: Brownout (low voltage) Detection on msp430F2274

texts:
I work on a Texas Instruments msp430f2274 with a battery. I want to know, when the supply voltage is low.
I found information about a "Supply Voltage Supervisor" but apparently it is not present in all devices of the msp430x2xx family. My controller has a brownout detection circuit and this triggers a POR (Power on Reset).
Now to the problem. I don't know how to use this POR signal or the BOR circuit. How do I detect low voltage on my controller and trigger specific events to save my data.


texts:
I'm planning to build a pwm driven H bridge. I have all set up, flyback diodes, pull up and down resistors on high and low on bridge's side, decoupling capacitors and so on, but I only have TIP122 Darlington BJT available at my university. I know I need a big base current to charge base capacitance as fast as possible to allow faster PWM frequencies. Unlike some FET's, it doesn't have "fast switching" written on its datasheet. But besides that, the datasheet lacks the "ON base input resistance" and the input capacitance, only output capacitance.

How can I say for sure that this BJT doesn't suits me? I'm planning using 100Hz for pwm


texts: Searching for a programmable microcontroller (USB & LED dimming)

texts:
My apologies for the lack of given information or my knowledge in this subject. I haven't done much electronic-related before (I know how to use basic IC's such as the 555's, 4017's, etc), but I've never worked with any microcontrollers before.

I'm basically searching for a (cheap/well-priced) programmable microcontroller which can connect to a computer through USB and be controlled via a Visual Basic (preferably) application and control the brightness of at least 7 different LEDs at the same time. I have no idea where to go looking for one that'd suit my needs, nor do I know what specifications it needs (other than what I've said).

As for programming it, I'm unsure of what I'd need to install the program onto it (some sort of device?), but any programming language is fine - I've been writing software for over 3 years, it shouldn't be a problem.

I'd also rather do it this way than buy a cheap Arduino clone so I can learn from this and have a project to do (despite not knowing much, electronics is a hobby of mine). I should probably also mention that I've been searching around for over 2 hours now, but not come across anything conclusive.

Any responses would be greatly appreciated, thank you :)


texts: Does adding the input signals change the behaviour of an amplifier?

texts:
I have these 3 signals, they differ by 300 Hz each. When I use any of these signals as input to a class B amplifier, I get the desired current amplification. The thing is, I have to input all these 3 signals at the same time to the speaker(my load). My plan to do it to use an adding op-Amp configuration. However, I wonder will the amplifier work properly or will there be any problems?
Also, what are the chances that I suffer from momentary excess voltages on
the load, an 8 ohms speaker in fact, which may result in damage to the speaker?
Thanks in advance.
edit : I don't know does it affect the question but I think I have to add that, actually at any time instant only two of the three signals will be active, and one of them will be lower in amplitude relative the other one.


texts: how to combine SPI input with websocket in nodemcu python

texts:
nodemcu is a very common device ,and i am really struggling for a long time with sending over wifi input spi data with python.
I google many times this sort of combination and tryind to assemble the code.Is there a good manual which could show how exactly to broardcast over socket SPI data?
Thanks.
from machine import Pin,SPI
import network
import usocket as socket
ap_if = network.WLAN(network.AP_IF)
ssid = 'sensor_net'
password = '123456789'
ap_if.active(True)
ap_if.config(essid=ssid, password=password)
s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
s.bind(('',80))
s.listen(5)
spi=SPI(1, baudrate=1000000, polarity=0, phase=0)
while True:
    spi.write(b'1234')
    conn, addre=s.accept()
    request='

The temperature is:
'
    request2=str(12.7)
    response='gyhkjgku'
    conn.send('HTTP/1.1 200 OK\n')
    conn.send('Content-type: text/html\n')
    conn.send('Connection: close\n\n')
    conn.sendall(request)
    conn.sendall(request2)
    conn.close()
    spi.write(b'1234')


texts:
I need to put an LED strip (ws2812) which uses 18watt per meters at 5V.
I intend to use 1 meter but the power supply is 10 meters away.

I can't use bigger wire than awg20 which I know will cause big voltage drop.
I thought about mounting multiple leds in parallel but it would need a tone of wires which is quite expensive.

Could I use something like a supercapacitor to help with the voltage drop?


texts: Calculate U(t) when capacitor C1 charges C2 via a resistor R

texts:
simulate this circuit – Schematic created using CircuitLab

The switch SW1 is activated at t=10s and charge from C1 is transferred to C2.
The power supply charges continuously with 1kV 1mA.

How can I calculate the voltage U(t) at C2?

What I have tried so far:

If there was no C1, I could write U2(t) = V1 * (1-exp(-t/((R1+R2)*C2))
My strategy was to start with
Q=CU
=> U2(t) = Q2(t) / C2
Say the current from C1 to C2 is Ia and
the current from the supply to C2 is Ib
Q2(t) =Ia *t + Ib * t
now I got stuck. What is next?
U1(t) =  Q1(t) / C1
Q1(t) = Q_recharged - Q_transferred_to_C2


texts: Hall effect sensor operational distance from magnet

texts:
I want to use a this hall effect sensor to detect the presence of magnet.  I'm pretty sure I understand how to use the hall effect sensor, but I'm not sure how to calculate the distance the sensor can detect a magnet of a given Gauss.  I'm not even sure that the Gauss rating is relevant to the question.

The Output On rating is listed as 35G and the Output Off is listed as 25G.  If I use a magnet like this one (13,200 Gauss), can it be detected up to 6 inches (15 cm) away?

I found an online calculator to use but it appears to calculate the rating between two magnets and not a magnet and a sensor.


texts: Source/Sink on 74AHCT2G125DC not driving WS2712bs

texts:
Per advice in this post I am using a 74AHCT2G125DC (datasheet) to drive a Neopixel/WS2812b strip's data pin from a 3.3v MCU. The MCU is driving A1, and the addressable LEDs are chained from Y1. VCC on the high side is 5V and the ground is shared.

I'm seeing numerous communication errors and flickers on the LEDs although there is no voltage sag on the 5V rail. Oscilloscope probing the input side of the 74AHCT2G125DC buffer shows a clean signal between 0-3.3v. Probing the output side shows a much noisier signal ranging from 1.2-5.0V. It never reaches the ground which I suspect is causing some of the issues.

What is the best explanation and how do I fix this? My current theory is that somehow driving down the LED chip's pin to GND must sink more than the current limit of the driver (8mA, if I read it correctly.) Or am I misunderstanding that a driver of this sort can feed a digital signal out to a device like a WS2812b? Is there any explanation for why on a low signal, the output doesn't fall to zero?

Note: The reason for using a tri-state driver is so I can shift the digital out to a high-impedance state during circuit shutdown preventing an observed current backflow to the MCU when the strip is unpowered.


texts: Capacitance via 555 timer & resonance. Sources and possible cure?

texts:
I apologise in advance if this topic has already been discussed here. I am no EE and have have no choice but to ask experts to move my project forward.

I am developing a capacitive sensor via a simple RC circuit to read the capacitance of an epee/foil tip. This is done via a 555 Timer running in monostable mode (Figure.1). The circuit uses DC power at approx. 4.7V from the 5V output pin of an Arduino MKR1000.
The expected capacitance of the sensor is small: 50 - 110 pF.
I am using a 240K resistor as the RC time constant. T = RC is approx. 22uS as measured with scope and ties with calculations.
When the weapon is not connected (switch open), the output of the 555 is stable and almost constant (reading approx. 70pF in 18uS). No resonance is observed at any sample frequency.
When the weapon is connected (epee/foil described as C1 in the circuit),  resonance for certain sampling frequencies is observed.

for high sampling frequencies (500uS per cycle, Figure 2.), capacitance oscillates, but stays "stable".
At lower sampling frequencies (above 1500uS per cycle, figure 3.), significant resonance can be observed and I am hitting harmonics at specific frequencies (2750uS/cycle, 3350uS/cycle, etc.).

I am also experiencing significant resonance when noise has been injected in the system. Figure 4. shows capacitance obtained from the sensor after the tip of the weapon has been depressed on the opponent's lamé (i.e. a conductive metal jacket). Figures 5 to 9, show the capacitance read by the circuit under various sampling frequencies. High frequencies seem immune to resonance while lower ones feature significant distorsions.
The circuit is in development (i.e. breadboard) mode and lines to the weapon system (denoted C1 in Figure 1, i.e. the connection sockets, 120cm twin-line wire connecting the circuit to the weapon and weapon blade) may constitute a source of significant Inductive Reactance, or at the very least parasitic Resistance.

So, my questions:

Q1- Since the circuit is a simple "class 1" RC (no inductor), what is the probable origin of the circuit reactance? (During my attempts to locate the origin of signal oscillation, I discovered that the main source is the body wire. Could a wire act as a coil and generate back emf voltage during the 555 phases?)

Q2- How can I reduce (eliminate?) resonance by making adjustments to my circuit? (i.e. other than simply avoiding resonance by way of "selecting" a sampling frequency which suits).

Q3- I understand that resonance is in part due to an amount of energy (or "noise") oscillating in the circuit which is not being converted. (Is this correct?) Is it possible to control noise in a circuit electronically?

Q4- Finally, how can I establish a frequency response function to identify the most significant resonant frequencies from the sampling of output capacitance (raw signal) only? (I realise this question is more of the signal processing kind, but I am asking here just in case someone has a ref. to share).

If you require more info/data, just ask, I'll do my best to provide it.

Figure 1.

simulate this circuit – Schematic created using CircuitLab

Figure 2.

Figure 3.

Figure 4.

Figures 5-9.


texts: Interfaces with differential pairs during PCB Design

texts:
I was wondering where I could find a list of interface which require differential pair or particular design rules ?

I know for example that USB require different pair routing. I identify them because their line are called D+ / D-.

However in another application I have a speaker and a mic which also have - and +, does this make them also a differential pair ?


texts:
I found this cable in a box of old bits. It is 4 wire and has test clips on one end and a barrel type plug on the other.

I am trying to find out what the plug is called and I hope to locate a corresponding socket.

The plug is about 40mm long and 9mm wide at the upper conductor.

The other end:


texts: What is this UP 4B2 smd chip in dfn8 case?

texts: Acts probably as a driver to power the motor. There a two of this kind on the board. One burned, the train drives only in one direction.


texts:
I'm not experienced in electronics and I need your help.

I have the circuit represented here, my intention is to put a dc motor working (in my case a water pump), using an Arduino Uno as a switch.

My water pump needs an input of 6 to 12 volts, 1.5 to 4 watts, but using this circuit I only have a voltage at my pump of 2.78 volts.

My battery is 9.6 volts, and I was expecting some voltage drop, but not that many.

Can someone explain me how to get some 6+ volts on my pump?

R220 - 220Ω
R10k - 1000Ω
T1 - 2N2222 A331
D1 - IN4007 KED
BAT9.6v - 8x 1.2V AA batteries
M1 - DC water pump JT-160 6-12V 1.5-4W

Edit:
The 10k resistor is actually a 1k Resistor


texts: Why would somebody be bothered to set Clock Polarity and Clock Phase for an SPI Master? Is this about the compatibility for Slave device? Is this somehow helping something? Why does it matter if the data is transferred on Rising Edge or Falling Edge ?


texts: I'm trying to write an electrical engineering paper about different I/O on mobile phones. The inputs, such as the camera, microphone, accelerometer, GPS, can be considered sensors. What's the equivalent word for the outputs, such as display, speakers, vibration, etc? I thought it might be haptic, but haptics are only for outputs involving touch.


texts:
I am trying to debounce a switch that controls the gate of a mosfet.
Will the circuit below work, or do I need to re-arrange some of the parts?
*The circle thing should have been drawn as a mosfet.


texts:
I'm trying to understand the effects of polygon pour fills when high speed line transitions might occur. Consider the fabricated case example below:

In this example the tracks (colored in light blue) were set as much apart as possible on the left of the board, but they had to be taken closer together to fit through the big pad holes. The red fill is the ground polygon pour. Notice that this is a fabricated example that has many other problems unrelated to my question.

For the sake of the argument, all lines are single ended (like UART, SPI, I²C, etc.) and may have transition times of 1~3 ns. There is a continuous ground plane below (0.3mm distance) but my question is specifically about the ground pour on the top.

In case C the polygon pour was able to penetrate to a place with enough room to place a second via connection, so the ground trace is properly conencted to the plane below. However, in cases A, B, D and E the pour made as far as it could with no space to place for vias, leaving GND "fingers".

What I'd like to know, disregarding other routing considerations, is whether "fingers" A, B, D and E should be removed or perhaps they contribute to reducing crosstalk between the tracks. I'm concerned that ground noise could make those "fingers" good antennas and produce unwanted EMI. But at the same time I'm reluctant to remove them for the possible crosstalk benefit they may have.

EDIT

For a diferent case example, consider this picture:

Fan-out from each IC imposes a reality where many of these fingers are unavoidable, except if we get rid of the GND pour entirely on that section. Is the latter the proper thing to do? Is the GND pour beneficial or rather innocuous as long as it is a GND fill?


texts:
Hi being a invoice I am not able to figure out what is the chip attached to motor

I got it from a non working toy. Is it a simple dc motor? Are the chip contain just resistor named as mc1, mc2? Or can I remove the chip and use it directly?

Does it looks like a 3 volt? I got it from fisher price toy.

Any help is appreciated. I don't want to take any risks as this is the  only motor I found to play this weekend.

Update:

It looks like it has magnet in it so can I somehow use it as a dynamo?

Update:
It is attached to the below PCB but not sure why main IC does not have any information on top of it and toy was powered by 6 aaa cells so 9 volt I think


texts: How to tell if chips overheat while soldering

texts: I am new to soldering and I am afraid that I am getting some of my chips too hot. I'm sure this will be less of an issue when I get more experience. I also ordered some DIP sockets but they won't arrive for a few months. In the mean time is there any way I can tell if I have damaged my chips? I am afraid that I won't by able to tell if I have made a mistake in the circuit on the protoboard or the chip is just damaged and malfunctioning. Generally speaking, can you destroy a chip with heat before it gets too hot to touch? I know datasheets list maximum temperatures but it seems like the temperature inside could get much hotter than the temperature you can feel on the outside.


texts:
The assembly house has a P&P machine (Yamaha i-pulse M4S) and the export file is from Altium.
All components are read from the machine fine except an LCC gsm module MG323-b which has a particular think that i'll try to explain:

As you see at the modules' guide Pin4 (marked A) has different dimensions from all the others. It is rounded while all others are square.

However on my PCB design I didn't use different footprint for that pin.

Do you think that this may cause the problem of the pick&place machine?
And if yes can you think of any solution of that problem ?

Best regards!


texts: How to automate Instantiation of modules in Verilog? (permutation)

texts:
Consider this file tb_sr_latch.v:

`include "sr_latch.v"

module tb_sr_latch;
        reg [4:0] t_in;
        wire out;

        sr_latch M1(t_in[4], t_in[3], t_in[2], t_in[1], t_in[0], out);

        initial begin
                $dumpfile("tb_sr_latch.vcd");
                $dumpvars(0);
                t_in = 5'b00000;
                repeat(32) begin
                        #1 t_in <= t_in + 5'b00001;
                end
        end
endmodule

there is a module instantiation which its name is M1, there can be other instantiation of this module to consider all possibilities and create all possible signals: for example for a module with 5 inputs it is possible to have 2^5 possibilities with (5! == 120) permutation ( because signals order matter) like:

 sr_latch M1(t_in[4], t_in[3], t_in[2], t_in[1], t_in[0], out);
 sr_latch M2(t_in[3], t_in[4], t_in[2], t_in[0], t_in[1], out);
 sr_latch M3(t_in[2], t_in[3], t_in[0], t_in[4], t_in[1], out);
  ...
  ...
  ...
 sr_latch M32(t_in[0], t_in[1], t_in[2], t_in[3], t_in[4], out);

Now my question is, is there any more pretty and automating way to do it?


texts: What are the challenges of designing high Q digital filters?

texts:
I am not familiar with digital filters and digital signal processing.
I do know that implementing an analog filter with a high quality factor is not practical, because (please correct me if I'm wrong) we are limited by the Q of active components in the circuit, and tuning a high Q filter is difficult. (Any other significant reasons?) We don't have these problems in the digital domain, do we? Is there a reason we would want to avoid high Q digital filters?


texts: What transistor to use when building a simple MCU controlled LED blinking circuit?

texts:
This is my conceptual schema to use a PIC12 to control the blinking of 3 LEDs with different blinking patterns. I have a few questions that would like to ask.

Is this circuit going to work?
What kind of resistors should I use?
What kind of transistors should I use?
Do I need capacitors or any other components?

simulate this circuit – Schematic created using CircuitLab


texts:
I'm building a 4-channel 0-10v power supply for controlling a set of dimmable Meanwell LED drivers.  I'm basing my design off this circuit:

I simply repeated the same circuit four times on the same perfboard.  Three of the channels work mostly as expected, outputting 0-9v without load.  The forth channel on the other hand is outputting 11-15v.  I'm driving the supply with a 12v wall wort.

I've double checked the resistance across all of the resistors, everything matches up exactly with the working channels.  I'm pretty much at the limit of my electronic knowledge, any hints at what to even check next would be helpful.

Here are some pictures of the mess that I have created:

The black & yellow leads go to the potentiometers. The corner pins marked black/red are the input +/-.  The pins sticking out between the caps is the output.


texts: Will my wires have current stability issues?

texts:
first post here.

I'm currently making a set custom sleeved/crimped cables for my computer's modular power supply, and my crimper isn't very good, so for extra security, I've soldered all the crimps, using flux so that they flow properly. They are male-and-female type connectors, and carry high current (~5A) 12V DC, as well as some slightly lower current 3.3V and 5V DC.

After soldering, I proceeded to clean them in ethanol/alcohol, however I'm pretty sure they still have a thin layer of flux in them since it's hard to clean inside the female connectors.

I've done testing with a multimeter by first inserting a male connector, then measuring resistance and diode checks from the inserted male connector to the other end of the wire, and they check out (~0.003 ohms, the same as an un-crimped wire, the resistance is probably caused by the multimeter probes anyways, I've checked the probe-to-probe resistance to be the same).

Now for my question: If my resistances check out, and Diode check passes, will I experience unstable current under high loads? (e.g 8 Wires for a 150W graphics card)

Thanks!


texts: Negative differential to instrumentation amplifier causing problems

texts:
I am using a pair of strain gauges to make a weight scale. The strain gauges are the three-wire type that you can by on Amazon or Sparkfun. The strain gauges form a full wheatstone bridge, whose differential output voltage varies from -6mV to around 10mV. I'd like to amplify this signal and then sample with an ADC. But my board does not have a negative voltage supply.

How can I shift the differential voltage so that it starts out non-negative, and remains positive for the rest of its swing. In other words, make the differential output from the wheatstone bridge go from 0mV to 16mV?

For reference, this is the circuit I am using, from the INA332 datasheet.


texts:
I have a home built radio which can take a voltage range of 2.2V to 3.6V.
I wish to use a Lion battery that is 3.87 volts when fully charged.
Can I sensibly reduce the voltage to 3.6 simply?
I have been told this can be done with a diode.


texts: Why is my MSGEQ7 circuit giving Arduino analog readings that are so high?

texts:
I have built the following circuit based on a proven MSGEQ7 based circuit design, which comes from the datasheet and elsewhere on the internet. I have built and coded to this circuit previously, with a 5V power supply, no problem.

The audio input is a sparkfun electret microphone breakout board with onboard op-amp-based amplification circuit. This too, I have successfully used on a previous project hooked up to the MSGEQ7. It worked fine there, but at that time I used an Arduino 3.3v pin to power this (here both the MIC BoB and the MSGEQ7 are on 3.3V rails).

The only difference between this circuit and the last one I built (that I can tell anyway) is the fact that I'm now running both MSGEQ7 and the BOB off a 3.3V rail.

The circuit "kinda" works, but the analog readings do not seem calibrated properly.

Here is a sample of the the output I'm getting:

RAW EQ      392 406 630 803 842 973 886
RAW EQ      341 818 936 1022    1022    1022    1021
RAW EQ      590 812 950 860 1023    1023    1021
RAW EQ      550 894 1022    1022    1023    1022    1020
RAW EQ      561 926 953 1023    1023    1022    1006
RAW EQ      565 805 918 966 1022    1023    1013
RAW EQ      525 835 1013    999 1023    1023    1022
RAW EQ      611 862 884 1015    1022    1023    1012
RAW EQ      541 794 802 849 1023    1023    1012
RAW EQ      449 759 993 928 1023    1022    1002
RAW EQ      400 858 1006    1013    1023    1022    1015
RAW EQ      460 876 934 1023    1022    1023    1013
RAW EQ      617 845 869 976 1023    1022    1022
RAW EQ      729 814 981 1023    1023    1022    1015

As you can see the last 3/4 bands are all pretty much maxing out!

Here is the relevant Arduino code:

Init Routine

//initialise MSGEQ7 chip
void initMSGEQ7(int analog, int strobe, int reset)
{
#if defined DEBUG
    Serial.println("MSGEQ init");

    Serial.print("Analog Pin");
    Serial.println(analog);

    Serial.print("Strobbe Pin");
    Serial.println(strobe);

    Serial.print("Reset Pin");
    Serial.println(reset);

#endif
//set up MSGEQ7 pins
pinMode(analog, INPUT);
pinMode(strobe, OUTPUT);
pinMode(reset, OUTPUT);
analogReference(DEFAULT);

//turn off comms to MSGEQ7 to start with
digitalWrite(reset, LOW);
digitalWrite(strobe, HIGH);
//prep the MSGEQ7 to read in the frequency bands
digitalWrite(reset, HIGH);
digitalWrite(reset, LOW);
}

Reading code

//read the EQ
void readEQ(int strobe, int analog, int (&bands)[7])
{
#if defined DEBUG
    Serial.print("RAW EQ\t\t");
#endif

//read in the bands
for (int i = 0; i < 7; i++)
{
    digitalWrite(strobe, LOW);
    bands[i] = analogRead(analog);
    delay(5);
    #if defined DEBUG
        Serial.print(bands[i]);
        Serial.print("\t");
    #endif
    digitalWrite(strobe, HIGH);
}
#if defined DEBUG
    Serial.println();
#endif
}

The question: How do I make this give me readings in a better spread from 0 to 1023 via the Arduino's analog inputs.

I have rebuilt the circuit a number of times, using completely new components (passives, IC, cable and the BoB), the results are the same.

I also have an unregulated 3.7V rail (from a LIPO battery) which I could use -- the 3.3V regulated supply comes from an Arduino Pro Mini 8MHz 3.3V edition which takes in the unregulated 3.7V LIPO power supply.


texts:
I need a circuit that converts a 3.3V signal into a 24V signal. But I also need to be able to activate the 24V signal using a PCB switch. I can do it in two ways, using a diode OR or using a transistor OR, which one is better? They both look ok in the simulation.

Diode OR:

Transistor OR:

EDIT:

After @BruceAbbott comment I'm adding a third simpler option, just short circuit the first transistor Q1:

V(n002) is the control voltage of the SWCTRL switch.


texts: what is the component with the circle mark?

texts:
I am trying to build an IR sensor module for line following robots, and I used QTRX-MD-06A module as my reference. The principle and PCB photos are attached here.

However, the component with a circle mark that is beside 47K resistor on the PCB is something I never saw before. I don't think it is a zero ohm resistor, because if it is, it means the light emitting diode will be directly connected to +5V and GND without any current limiting resistor. It would burn the diode, wouldn't it?

Would anyone please let me know what it is? How does it relate to the current source symbol in the principle photo? Thanks in advance!

[Answer]

It turns out, there is a dedicated LED driver IC connected to the cathode of the light emitting LED. I guess this IC controls the LED current, and thus there is no need to use a current limiting resistor. So that component is indeed a zero ohm resistor.


texts: Variations in RFID USB Serial reader detection distance by connected device

texts:
I have a RFID reader that sends the TAG information over USB serial. I have had some troubles with it in a product where the detection success rate changes alot depending on what the USB RFID tag is connected to, even between devices of the same kind but larger variations in different types devices it is connected to. To name a few examples of the detection distances

-Connected to laptop PC: 5cm

-Connected to USB hub which is connected to PC: 4.5cm

-Connected to an embedded linux box: 3cm

-Connected to a display unit (which has an internal hub) which is connected to the linux box: 1.5cm

-Connected to a USB hub (same hub as PC case which had 4.5cm detection distance), which is connected to the display unit which is connected to the linux box: 1.7 cm.

These connection arrangements all result in various usb hub depths of 1-3, but there isnt a straight relationship here between hub depth or device and the detection distance. In all these cases the RFID reader was plugged to a USB extension cable and taped down to be measured in the same spot with a plastic ruler.

Is this a common phenomenon? Detection distance being so reliant on whats on the other end of the chord. There doesn't seem to be a strong correlation with a circuit/hardware issue. It feels like a software/system issue. There is some traffic on the hubs in the situations where the detection distance drops but you would think that the actual detection distance would be entirely dependent on the near surrounding of the RFID reader, not what device it is connected to 30cm away.


texts: Core stucks in blocking handler STM32F103C8T6 libopencm3

texts:
I have problem with my STM and the libopencm3. After the reset handler is called, there is immediately jump into blocking handler.

I suppose that the hard fault occurs.

Here is the call stack:

??@0x07fffd545
<signal handler called>@0xfffffff9
reset_handler@0x0800017a

And the linker script:

MEMORY
{
    rom (rx) : ORIGIN = 0x08000000, LENGTH = 64K
    ram (rwx) : ORIGIN = 0x20000000, LENGTH = 20K
}

/* Enforce emmition of the vector table. */
EXTERN (vector_table)

/* Define the entry point of the output file. */
ENTRY(reset_handler)

/* Define sections. */
SECTIONS
{
    .text : {
        *(.vectors) /* Vector table */
        *(.text*)   /* Program code */
        . = ALIGN(4);
        *(.rodata*) /* Read-only data */
        . = ALIGN(4);
    } >rom

    /* C++ Static constructors/destructors, also used for __attribute__
     * ((constructor)) and the likes */
    .preinit_array : {
        . = ALIGN(4);
        __preinit_array_start = .;
        KEEP (*(.preinit_array))
        __preinit_array_end = .;
    } >rom
    .init_array : {
        . = ALIGN(4);
        __init_array_start = .;
        KEEP (*(SORT(.init_array.*)))
        KEEP (*(.init_array))
        __init_array_end = .;
    } >rom
    .fini_array : {
        . = ALIGN(4);
        __fini_array_start = .;
        KEEP (*(.fini_array))
        KEEP (*(SORT(.fini_array.*)))
        __fini_array_end = .;
    } >rom

    /*
     * Another section used by C++ stuff, appears when using newlib with
     * 64bit (long long) printf support
     */
    .ARM.extab : {
        *(.ARM.extab*)
    } >rom
    .ARM.exidx : {
        __exidx_start = .;
        *(.ARM.exidx*)
        __exidx_end = .;
    } >rom

    . = ALIGN(4);
    _etext = .;

    .data : {
        _data = .;
        *(.data*)   /* Read-write initialized data */
        . = ALIGN(4);
        _edata = .;
    } >ram AT >rom
    _data_loadaddr = LOADADDR(.data);

    .bss : {
        *(.bss*)    /* Read-write zero initialized data */
        *(COMMON)
        . = ALIGN(4);
        _ebss = .;
    } >ram

    /*
     * The .eh_frame section appears to be used for C++ exception handling.
     * You may need to fix this if you're using C++.
     */
    /DISCARD/ : { *(.eh_frame) }

    . = ALIGN(4);
    end = .;
}

PROVIDE(_stack = ORIGIN(ram) + LENGTH(ram));

How can I debug what causes this error?


texts:
I am looking for an ADC for my project and there are a few features that I don't quite get. On TIs product selector. The default filters includes INL, SNR, SFDR. I assume they are important since but some of them have value some dont, so I assume its ADC-spefic (or maybe they did not just write it) not all ADC have them, being just initials makes it harder to search.

Here are others on which I need some advice:

Programable Gain Amplifier(PGA) - Assuming same sample speed, Which would be better a 16-bit ADC using internal gain or a 24-bit (or 32-bit) ADC that is using no gain. Gain also amplifies the noise but assuming the isolation is perfect, wouldn't the 16-bit with a gain of 2 or more be better to the 32-bit using no gain? Of course there is gain drift but at low gains it's not much.

Simultaneous or Multiplexed Sampling - Although this one is self explanatory, Isn't simultaneous sampling (for multiple channels) always better? Are there other notable reason why to choose multiplexed over simultaneous?

Here are 2 ADC that have very peculiar features about which I have no idea:

AC excitation (ADS1261)
50/60Hz notch (ADS1243)

Those two interest me because what I plan to use my circuit is to read voltages from a current transducer so that I can get the current consumption of a mains line.

Also what are all these gold for? are there really applications for it? gold, more gold


texts: Inductive Crankshaft Position Sensor Voltage Drop When Split Between Inputs

texts:
I'm working on a project with a vehicle using two engine control modules, which both need accurate crankshaft position signals to function. Adding a second sensor is not an option. The sensor is an inductive sensor producing a semi-sinusoidal waveform, NOT a Hall-Effect sensor.

The issue I have been seeing and have tested is that as the frequency of the inductor is increasing, i.e the vehicle RPM is increasing, the voltage applied to one of the modules is leveling off. I measured the sensor to produce a voltage of around 12VAC at ~7000rpm, however when split one of the connections measured at only 4VAC. The frequency measurements were correct for both computers, however I believe that they also use the applied voltage to determine engine speed.

I do not have any technical documentation for this sensor, as it hasn't been made public to my knowledge.

What are some possible solutions for this problem? I have considered using an opamp but am unsure how that would improve the situation.


texts: Why does current associated with a rectifier said to have both ac and dc components?

texts: Why does current associated with a rectifier said to have both ac and dc components. Also how are they combined?


texts:
Datasheet LTC4370

Background:  I want to use this chip to combine the power output of two 2.4A USB ports on a USB power bank I have. If this is possible it will output ~25W and w/ my dc-dc converter I should be able to charge my laptop using USB power banks. If possible in the future I may buy 2 chips more to combine 4 USB outputs.

I presume I will be using a design very similar to the typical application on the first page of the datasheet, but with the values listed in the 5V example on page 14. I might need to adjust the resistor on the range pin depending on how close the Vout on the USB ports will be.

Question: page 11 of the datasheet, MOSFET selection, the last paragraph's phrasing confuses me. I can't tell if it wants me to get a Rds(on) value as close to what the equation gives, or if that is a maximum value for Rds(on) and anything below should suffice. The given equation is ΔVIN(SH) = VFR(MAX) – 0.5IL • RDS(ON),

VFR(MAX) is the maximum forward regulation voltage (Vin-OUT)
Vin(sh) is the "sharing capture range"...not sure what that means
what IL is has proven elusive as well... wish I knew what these all were

I could always use a very similar MOSFET to the SUM85N03-06P in the typical application, and ignore the equation altogether but avoiding errors would be cool, and who doesn't like to learn?


texts:
its been a while since I did anything with mosfets and completely forgot how to do anything basic anymore with them. I was wondering if anyone can lead me back on the right path.

For the past week I tried finding examples of how to bias a common source configuration however, in almost every practice question I find they give you pretty much all the information such as ID, Kn, etc like here:

I would think that designing an amplifier ID (Drain Current) would be a variable that you would need to find through your design spec.

and when reading the IV-Characteristics curve I am totally lost. I get you want to pick a point in the saturation region so you can exercise your full voltage swings but how does one find the correct VGS and ID and VDS to do this?

Another question about the IV Curve. When you do find your specific point, and let say its at ID = 20mA and VGS = 5V, VDS = 10V does this mean the mosfet will provide 20mA and the drop across VDS will be 10V? or is the mosfet capable of allowing 20mA through the drain? If so is this constant across all voltage supplis and not invalidating ohms law?

The way I think things are done are as so (Not having an RE/RS resistor
VS = 0):

Design Spec
P = 20W output
RL = 8ohm (Speaker load)

Use the power equation to see how much voltage I need at the output and that will determine my power supply.
Find the transfer function of the CS Amplifier then solve for RD to find my desire gain I need (However how do I find my Gm, and ro value?)
then I guess I have enough to find my ID? and from here I guess I iterate different values to where i want to be in the saturation region?


texts:
In my circuit, I have the L1 ~ L8 LED as indicator LEDs on the even number pins of my header. TEST rail is connected to a +5V rail which can be turn on or off depending whether I want the indicator LEDs to turn on or off (the problem described below exists in both configurations).  A ~ H are controlled by a microcontroller which grounds the pin when I want to turn an LED on. That part of the circuit works as I have checked that it does indeed short to ground when I pull the pin low in the program.
On the odd number pins on my header, I plan to attach some kind of output loads powered by a +15V rail that can supply higher current. Right now, I just have bright LEDs as load, but it ideally could be any other actuator.

The problem is that for some reasons, the current seems to be able to pass through the indicator LEDs and provide a path to the ground. As a result, there is always some voltage across an output LED which causes it to stay on all the time. The output LED would simply become brighter when the signal pin is pulled to the ground.

I tried removing the "Test LED". After doing that the output LEDs will still turn on dimly as long as one of the signal pins is pulled to ground.

Does anyone know why the indicator LEDs don't act like a normal diode? Is there something wrong with my design or something wrong with the particular LEDs that I bought??


texts:
I posted a question a while ago about a circuit to realize a voltage controlled phase.  I wasn't able to give a full discussion about why I was interested in the circuit at the time but I am in a position to do so now.

I have filed a provisional patent for "phase shifting commutation" with this abstract:

  The apparatus employs magnetoresistive sensors (28) to generate a sinusoid having a time-varying frequency commensurate with the angular rate of change of a motor’s rotating shaft (40).  The resultant signal is then fed to a mixture of fixed- and voltage-controlled phase shifting circuits (22, 64) (32) whose outputs are then amplified and fed to independently wired stator phases (56).  The apparatus also includes a rotary transformer (24, 36, 46, 60) whose current is generated by amplifying a frequency-shifted version of this shaft sinusoid.  The rotary transformer (24, 36, 46, 60) in turn supplies current to the rotor system’s electromagnet to generate a controllable magnetic on the rotor system despite the rotor system’s motion.

My former employer is investigating this methodology and has the right to use the technology but I am in control of the IP.  I am building a mini dynamometer chassis with BLDC motors and I want to build the circuitry to achieve this commutation technique so that I have something to demonstrate.

A voltage controlled phase shifting circuit seems entirely achievable as there are many available off the shelf that operate with center frequencies in the GHz range.  Also consider that this technology is key to phased-array systems.

So I am wondering if anyone can help me build this phase-shifting circuit or can recommend some solution that I don't know about.

Off-the-shelf phase shifting circuit
Detailed discussion of phase shifting circuits
Previous thread of discussion


texts: What does it mean for a "baseband" signal to be a signal near zero frequency range?

texts:
I'm trying to understand the intuition and math of "baseband." Wiki says it is a signal near zero frequency range. Don't all signals of any type need a frequency otherwise they are not a signal? By definition an electromagnetic wave has a frequency, so I thought.
The next mystery is that wiki says the signal is near the y axis. An example I read is "telephone signal." In what sense does a telephone signal jump up and down the y axis and at the same time is near zero in frequency?
My motivation here is to learn AM and the word "baseband" keeps appearing as I read so need to undertand the lingo of baseband first. One hurdle at a time.


texts: Correlation b/w output voltage frequency and angle theta for Conventional Space Vector PWM 3-Phase inverter drive

texts:
Im writing code for SP-PWM for a 3 phase voltage source inverter but since im
a bit naive to the topic I need some clarifications regarding some questions I have.
Lets cut to the point.
For 3-phase system, we can transform the 3 phase quantities it to a d-q frame via following transformation matrix.

Where Van,Vbn,Vcn are phase voltages for WYE connected load at Va-Vb-Vb lines of inverter legs as shown below.

Now, we need to rotate the voltage vector Vref in d-q frame.

I can compute the magnitude of Vref and time required by each mosfet to change its state. But there is some nomenclature im not familiar with, such as switching freqency term, given by Tz = 1/fz. We need switching freqency, lets say 900HZ, which will give us 1.11ms Tz, using this assumption we can compute T1,T2 and To.

My Questions:

Q) How does varying angle of Vref in d-p frame(lets say we increment angle by 10 degree in each sector) will affect my output voltage frequency ?

Q) How does varying switching freqency(please also define switching freqency in terms of this SVPWM) affects the voltage output freqency of the inverter ? Is there any relation b/w them ?

Q) What can I do produce a variable output voltage freqency ? (i.e how parameters will be varying in such case ? )


texts:
I'm looking for a CNC machine that can be used for different PCB manufacturing tasks such as:

Drilling PCBs (using a rotating head)
Pick and place (to assemble PCBs)
Soldering

This CNC does not have to be heavy-duty, I'm just looking for some decent accuracy to deal with SMD parts.

A while ago I found the Lumenlab Micro CNC which was modular and multi-function, but they seem to have stopped production.
The RepRap seems to be a 3D printer only, I don't think you can do anything else with it.
The Makerbot is another 3D printer.
The ShopBot Desktop is a multi-function CNC and lathe, but only for drilling/plotting/engraving.
The redFrog PnP machine is a low cost hobbyist Pick n Place machine that works for SMD parts. About the lowest cost machine you can find.
The OpenPnP project documents an incomplete Pick n Place design. But you must build it yourself, nothing to buy here.


texts: How do I find the current through a motor caused by a PWM signal?

texts:
To investigate the effects of changing the PWM frequency and inductance from a motor I want to model the current flowing through it.

First I calculate how the voltage signal going through the motor phase will look like. So far so good:

Now I want to find out what the current is caused by this voltage signal. For the motor I'm using the following is true:

$$U = R \cdot I + L \cdot \frac{dI}{dt} +\frac{RPM}{k_V}$$

There are two different situations:
PWM signal is high
$$U_{supply} -  k_V \cdot RPM = R \cdot I + L \cdot \frac{dI}{dt}$$
PWM signal is low:
$$-  \frac{RPM}{k_V} = R \cdot I + L \cdot \frac{dI}{dt}$$

Both equations have the same homogenous solution:

\begin{equation}
\begin{split}
R \cdot I + L \cdot \frac{dI}{dt} &= 0\\
L \cdot \frac{dI}{dt} & = -R \cdot I \\
\int L \cdot \frac{1}{I}\cdot dI &= - \int R \cdot dt \\
\end{split}
\end{equation}

By intergrating on both sides I get:
\begin{equation}
\begin{split}
L \cdot \log(I) + K_2 &= -R \cdot t + K_1 \\
\log(I)&= -\frac{R}{L} \cdot t + K_3 \\
I&= e^{-\frac{R}{L} \cdot t + K_3 }\\
I&= K \cdot e^{-\frac{R}{L} \cdot t}\\
\end{split}
\end{equation}
The derivative is:
$$ \frac{dI}{dt}= -\frac{R\cdot K}{L}\cdot e^{-\frac{R}{L} \cdot t} $$

I think I did something wrong in one of these steps since if I fill this in the situation of PWM being low I find:

\begin{equation}
\begin{split}
-  \frac{RPM}{k_V} &= R \cdot I + L \cdot \frac{dI}{dt}\\
- \frac{RPM}{k_V} &= R \cdot K \cdot e^{-\frac{R}{L} \cdot t} - L \cdot \frac{R\cdot K}{L}\cdot e^{-\frac{R}{L} \cdot t}\\
- \frac{RPM}{k_V} &= R \cdot K \cdot e^{-\frac{R}{L} \cdot t} - R\cdot K\cdot e^{-\frac{R}{L} \cdot t}\\
- \frac{RPM}{k_V} &= 0\\
\end{split}
\end{equation}

This is simply not true, what did I do wrong?


texts: Can I use PIR + HC-06 Bluetooth Module without arduino to send events to Android?

texts:
I want a PIR sensor to send a "something moved" event to Android.

Can I use a simple PIR + Bluetooth module to send such an event?
I was thinking that I could connect the PIR output (which goes 5V when movement is detected) to the TX of the bluetooth module, so that "something" would be sent to android (which has been paired before), which would read "something" from instream.read(buffer)

Would this work? Is it ok to just put +5V on the TX of the bluetooth module? I would say that it would send garbage, but I'm not interested in "what" is sent, just the event that something was sent...


texts: Can I extend a single twisted pair DSL line using a coaxial cable?

texts:
I'm in the process of setting up a DSL modem/wifi router, which should be connected to a phone line that uses a single twisted pair. However, the phone line enters my house in a slightly inconvenient location. I could run a phone cable to a better location, but my house already has coaxial cables running through it, that I'm not using otherwise.

Can I connect the phone line to the coaxial cable, and plug in my modem at the other end? They're both pairs of copper wires; or is there a reason this shouldn't work?


texts: The datasheet states that TPS2400 protects the load from an over-voltage, by disconnecting the load from the power supply (Q1 goes off), without blowing the fuse. Why is the fuse F2 here, if there will be no current flow at over-voltage or under-voltage condition?


texts: Wiring a 24-volt Swamp (Evaporative) Cooler for Control With Relays

texts:
I am attempting to build a raspberry pi controller for my MasterCool swamp cooler, which has a rather dumb controller. The cooler has the 24V low-voltage control kit (as opposed to 120V or 240V direct control) installed.

Today I was messing with the control wires after popping the thermostat off, and mistakenly jumpered some of the connections, blowing the fuse. I've ordered new fuses, but in the mean time, I'm not sure how to properly control the blower (high and low) as well as the water pad pump and drain pump. I have terminals in the cooler labeled FAN, PUMP, 24V, COM, and DRAIN. I've confirmed that I have about 24VAC between the 24V connection and COM. The other connections all seem to have 0 potential difference with ground.

Given that I want to avoid blowing more fuses and doing this wrong, how am I supposed to power the various components? Should I be jumpering them to the 24V line? Do I need resistors to limit current?

Thanks for reading, hope I've not messed up in some way, this is my first SE post.


texts: Instrumentation Amplifier - is it possible to have an output signal inverted, with respect to the supply voltage?

texts:
I'm doing some circuit design in order to translate a load cell input into the pedal input of a Logitech G27. What I want to achieve involves having a balanced state output as close to 5V from the amplifier as possible (the original pedal outputs 4.9V, using a potentiometer as a voltage divider to measure the travel), and at full load on the load cell have a lower voltage (original reads 1.4V at full load).

Circuit simulation: here. Sorry, I haven't translated it to CircuitLab, hopefully this will suffice. Based on a design from here, albeit the design there is using an INA122 (similar to the INA126, but with different internal resistances which alter the gain calculation).

What I currently have is a straight amplifier circuit, using an INA126 IC. The load cell is a half-bridge model, with 1000 ohm resistance at no load on both sides. At max compression, the resistance changes to roughly 1002/998 ohm on respective arms. This resistance difference is converted using a Wheatstone bridge by the INA126 (represented in the simulation as a single op-amp, since the simulation only has singular op-amps; the INA126 is a two op-amp instrumentation amplifier with an external gain resistor, setting the gain to roughly 1000; and having internal feedback connections [datasheet]).

In terms of voltages available, I only have one 5V source, and no negative voltage supplies available.

Is it possible to reconfigure this circuit to output on a 5v-0v scale, rather than 0v-5v, without adding any more op-amps or ICs? Or will another rail-to-rail op-amp be required, purely to invert the voltage on this scale?


texts: What factors play into choosing type of MCB (Circuit Breaker) which is B16 vs C16 vs D16?

texts:
Found these discussions and Q&As online around this and am trying to determine how/ when one would decide to choose which way to go?

http://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=25220

Type B - trips between 3 and 5 time full load current

Type C - trips between 5 and 10 times full load current

Type D - trips between 10 and 20 times full load current

I will quote more information from the above thread as we begin to understand it more.

A simpler Q&A not as detailed assessment of factors as above discussion thread.

https://uk.answers.yahoo.com/question/index?qid=20130531054018AAVHMEw

Reference link mentioned in the answer:
http://www.electrical-installation.org/enwiki/Fundamental_characteristics_of_a_circuit-breaker#Short-circuit_relay_trip-current_setting_.28Im.29

Short-circuit relay trip-current setting (Im)

Short-circuit tripping relays (instantaneous or slightly time-delayed) are intended to trip the circuit-breaker rapidly on the occurrence of high values of fault current.

There is some insight on this question but its brief and specific and does not clarify or explain which to choose in other scenarios & why?

Working house main Control Miniature Circuit Breaker(25A) instead of transfuse (16A)?

Also will be sharing photos of existing ELCD/ MCB scenario at location for which the above fundamentals / factors need to be understood and then to arrive at a decision.


texts: Testing batteries by measuring their short circuit current, why it doesn't work?

texts:
I've experimented a little bit with some of my old, rechargeable batteries. (They "slept" around 5 years in a cabinet. I've long forgot their previous charged status.) What I did:

I've measured their voltage. It was okay, maybe a little bit lower as their nominal voltage.
I recharged them: I gave them around 12 hours in a battery charger. Unfortunately, this battery charger didn't give me any information, with the exception of a led showing, some type of charging actually happens.
I've measured their voltage again. This time, it was better.

Earlier I experienced that completely (or near completely) exhausted batteries give their nominal voltage measured by a multimeter, but it doesn't mean, that they could produce usable power on load.

My idea would be, that if measuring the voltage doesn't show anything about their power, maybe measuring their short circuit current would. Yes, I know it harms the battery, but I think, for the some seconds while I read the current on the display of my multimeter, it is practically negligible. And knowing the voltage, and their short circuit current will show, if they are really usable or not.

One of my friends (professional electric engineer) said, it is a bad idea, but he didn't explain clearly, why.

So, why is it a bad idea? How could I test a battery, if I have only a multimeter?

(P.s. they are NiMH batteries, if it matters.)


texts:
simulate this circuit – Schematic created using CircuitLab

My question is, because the delta primary in this case is connected A-C, rather than A-B, does this effect the direction of the 30 degree phase shift? I have read that if the primary is connected A-B then the primary phase is leading, and if it is connected A-C the primary phase is then lagging the secondary by 30 degrees. Can somebody please shed some light on this for me? I would like to know exactly what is shifting, leading or lagging, and why.
Thank you !


texts:
I am trying to derive the conversion from dBm to dB\$\mu\$V. So, please correct me If I am wrong.

\begin{align}
\textrm{dBm}
&= 10 \log_{10} \left( \frac{P}{1\textrm{mW}} \right) = 10 \log(P) + 30 \\
&= 10 \log_{10} \left( \frac{ V^2}{Z} \right) + 30\\
&= 10 \log_{10} \left( V^2 \right) - 10  \log_{10}(Z) + 30\\
&= 20 \log_{10} \left( V \right) - 10  \log_{10}(Z) + 30\\
&= 20 \log_{10} \left( \frac{V}{1\mu V} 10^{-6} \right) - 10  \log_{10}(Z) + 30\\
&= \underbrace{20 \log_{10} \left( \frac{V}{1\mu V} \right)}_{\textrm{dB}\mu V} + \underbrace{20\log_{10}\left( 10^{-6} \right)}_{-120} - 10  \log_{10}(Z) + 30\\
&= \textrm{dB}\mu V -120 - 10  \log_{10}(Z) + 30\\
&= \textrm{dB}\mu V -90 - 10  \log_{10}(Z) \\
\Leftrightarrow \\
\textrm{dB}\mu V &= \textrm{dBm} + 90 + 10  \log_{10}(Z)
\end{align}


texts: When the power of the kit 8085 trading kit is turn on, UP-85 is displayed. How is it possible something is displayed even before entering anything?


texts:
I designed a board and sent it to China to have the PCB made and parts assembled.

It contains an ARM CPU and a Micrel physical ethernet chip.

I used a FOX Oscillator FXO-HC536R-25 (25 MHz) to drive both the ARM and PHY.

The OSC stated output cap at 15 pF.  Both the ARM and PHY had 5-7 pF at the EXTAL inputs.

I could not connect JTAG to the CPU so started to see what issue might exist.

I'm using a 100 MHz 1 GSa/s Rigol scope to look at the OSC's output pin.

I get a sinewave with period of 6 ms.

Power, Enable, and Gnd voltages are all good at the OSC.

I considered the CPU and PHY might be loading the OSC's output so I cut the OSC output trace separating it from all other traces.

Same sinewave after removing it from the circuits it was driving.

I'm an old EE but mainly software the last 40 years.

Can anyone make a suggestion on how I should proceed from here?

To me it appears the FOX OSC is not running correctly -- what would cause that with no loading?

Is there some issue that can occur during assembly that could be causing the issue?  It is SMD with the pads under the OSC's can.

If you look at the actual pic of the board, you can see I cleaned the solder mask from the 3 traces to actually measure the voltages on the trace/pad of the OSC.  You can also see where I cut the trace just before the via to remove all loading from the OSC.

Scope probe X10.

Decoupling Cap C21 just below OSC

I acquired 10 prototypes.

I've tested all 10 and the same OSC behavior.

I did notice something.  When power was applied I get a 166 hz sinewave.  I turn off power and as the voltage decays, the output turns into a square wave, reduced amplitude but increased freq -- can't tell exact freq since it decays quickly.

I ordered some oscillators from Mouser -- be here next week.  I will update my status at that time.

UPDATE:

I called FOX this morning and spoke with a couple of very nice Engineers.

Turns out -- I was the problem!!!  I come off of my 3.3v regulator and derive 3 separate 3.3v power rails:  Digital, Ethernet Analog, and Audio Analog.  Each rail has a ferrite bead to isolate them.

25 mhz oscillator don't like ferrite beads in the power suppy.  The OSC requires about 20 ma to startup and the ferrite bead prevents this from occuring.

I removed the ferrite bead and replaced it with a jumper -- OSC works as it should now.

Thanks for comments.


texts:
In order to get an output of 100V-300v (for the ultrasound piezo drive ) from a 3.3V output of the microcontroller.
I have built the boost circuit according to this circuit:

But there is one point that I donnot quite understand- the +UB.
 I thought that it's the output, so I connect it to the oscilloscope, and I got the results as showed in the picture.

If +UB is the output, I can only have 10V as maximum as provided by Vcc.
Can you help me to find  the problem in my circuit ? Thanks!


texts: Determening the location of a ball contacting a surface

texts:
I'm a student currently working on a project. I have two objects, one of which is a plastic ball. The other is a rectangle which is being hit with said ball. My goal is to detect a position of a hit. The rectangle is about 5x5 cm. What would be the least intrusive way of sensing a position of a hit?

Perhaps I could use some kind of sensors on the rectangle to try and triangulate the position? Maybe put a small magnet on a ball (d=3cm) and with a help of small coils on the rectangle to calculate the position (could that work? or is it just stupid?) Small current would induce on each coil.
How about putting a thin metalic film on the ball and an array of small (+) pads and an array of detection pads (grounded via pulldown resistor)? Like a matrix.


texts: Opamp isolation resistor calculations for a capacitive load

texts:
I want to add a capacitive filter for pulse shaping to the output of a transimpedance amplifier using an OPA847.  Without the filter, the amplifier works great.  With the filter, I get some oscillation because the filter presents a ~40pF capacitance to the TIA output.

The OPA847 datasheet recommends using a series isolation resistor to separate the capacitive load from the feedback circuit:

They give recommended values for a 20 V/V gain, and further state:

  The criterion for setting the RS resistor is a maximum bandwidth, flat frequency response at the load. For the OPA847
  operating in a gain of +20, the frequency response at the
  output pin is very flat to begin with, allowing relatively small
  values of RS to be used for low capacitive loads. As the signal
  gain is increased, the unloaded phase margin also increases.
  Driving capacitive loads at higher gains requires lower RS
  values than those shown for a gain of +20.

This is indeed the case, if I use the recommended 30 ohms (for 20V/V) in my transimpedance amplifier, the oscillation is hardly damped.  I could just keep trying larger values until it works, but I'd like to understand how that value of 30 ohms is calculated, and how it would be calculated in the case of transimpedance amplifier which has transimpedance gain rather than voltage gain.  This is probably obvious, but I'm missing something.

Edit:  Here is a diagram of the the transimpedance amplifier and with a capacitive load:


texts:
What are the input resistances of the following biased amplifiers.
I know RG1||RG2 is the input resistance of the first one. But i can't understand how.
Is it RG+RD for the second one?


texts:
Is it mandatory to metallize the holes for the DIP package on a single-sided printed circuit board?

And is it necessary to metalize the holes for the jumpers if they are on the outside of the conductive pattern?

The document says that it is not recommended to make metallized holes on a single-sided printed circuit board.

The reason I choose to do this on a single-sided PCB is that I have already described everywhere that this is a single-sided printed circuit board in the documentation, to my work. Correspondence of documents will take a lot of time.


texts: Altera optimisation: "Stuck at GND due to stuck port data_in"

texts:
I am compiling Verilog code with the Quartus II compiler, and it seems that almost all my code is being optimised away. The "compilation report" says that many of my registers are being removed during synthesis because

  Stuck at GND due to stuck port data_in

or

  Stuck at GND due to stuck port clock_enable

What do those obscure messages mean? What is data_in and clock_enable? (They are certainly not some of my signals.)


texts: I am trying to find the collector's current of each transistor in order to find the transconductance gm of both, but I don't know how to relate the currents of them. There's any approach? Thanks


texts: Help identify SMD part - and why is the last letter rotated?

texts:
New to this. There're two parts in the image. I think one is a dual transistor and the other is a dual diode. But I couldn't pinpoint what they are.

And can someone explain why the last letter is rotated 90 degree?