texts: Problem in selection of state variables of inverted pendulum

texts:
I was reading about controller design from the book Control System Design, An Introduction by Bernard Friedland.
In one of the examples of controller design for an inverted pendulum, the author considered two state variables (e.g. angular position and velocity) as shown in the figure.

But to my knowledge for controller design, we have to select minimum number of independent state variables and then connect the gains via feedback to input of motor.
So in my understanding, there should be only one gain (that is connected to gain via feedback to input of motor) because system is a pendulum of some mass so we have only one energy storing element (e.g. mass of pendulum) so we need only one state variable to design controller.
So why does the author take two state variables instead of one for controller design?


texts:
I have been working on QTouch Implementation for ATmega32 Micro controller.
I have taken reference from here. I'm facing issue with grounding Problem.
For debugging process I am displaying the result of ADC channel on UART terminal. I have used 125Khz ADC Prescalper and AVCC as REF voltage with 0.1uf cap  on AREF pin.

When my ATmega16 is connected to My laptop with AVR USB programer and USB-TTL converter, Result varies from 400-550 on terminal without touch. when touch is perform it goes upto 580-620. I have code to blink LED when it touched (i.e. ADC value goes upto 580+). It blinks when touched an stay off when no touch.

but when I give external supply voltage from an adapter and remove USB programmer and TTL-USB converter, it starts blinking without touch.

When I have measured voltage of VCC in first case (i.e. Without adapter), it is ~4.56V. When I connect external Adapter VCC is ~4.95V.

when I have connected external adapter with the ATmega16 (~4.95 VCC), and USB-TTL for debugging(USB AVR Programmer disconnected). when there is no touch ,ADC Valu goes up to 528. when It touched , ADC value goes to 530+.

I have again code to blink LED when it touched(i.e. ADC value goes up to 531+). it works but when I remove USB-TTL from ATmega16, LED blinks without touching capacitor sensor.

It is grounding issue clearly. but how to get it solved? I have put 1M Rs sense resistor between ATmega ADC0 and Capsense.
here is a schematic of circuit I used.

here 0.1uf on power rail is not shown but it is exists on board.
I have a development board with take 12V and used LM7805 for 5V regulator.
I have used 5V 3A supply directly on VCC-GND of Atmega16, though same result.
I am not getting where the problem is?
I am seeking a direction please throw light on my path.

Wait for Positive response. :)
tanks in advance


texts: I have a dependent current source which depends on external pressure given by quadratic equation. Is it possible to simulate it in LTspice and see the graph between voltage or current and pressure?


texts: Schematic for common buck/boost converter designs

texts:
Does anybody know the schematics of these common LM2596 buck converter with current adjustment and buck-boost converters from ebay?

I know I can easily buy it cheap but I like making my own modules for education purposes and also find it fun to make it myself. I basically aim to replicate these modules, learn how they work and see if I can improve them in anyway if possible.

Link: Buck converter

Link: Buck-boost converter

Link: Boost-buck converter


texts: What does the value "Z" in the function table for this inverter stand for?

texts:
I came across a simple hex inverter IC with the truth table having "z" as an output state for a low (L) input.
So what does Z stand for here? Does it mean a toggle or partial state?
The other variant of this IC which does not use open drain outputs has the usual Function table of an inverter.

Function table(usual):

Input|output
L    |   H
H    |   L

Function table(with open drain):

Input|output
L    |   Z
H    |   L

The device description is as :

  "The device contains six independent inverters. These devices perform the Boolean function Y = A. The open-drain outputs require pull up resistors to perform correctly, and can be connected to other open-drain outputs to implement active-low wired-OR or active-high wired-AND functions"


texts: What heuristics are there (if any) to know how close a circuit is to a function?

texts:
I'm working on an AI project for circuit minimization.

I'm trying to think of a heuristic to tell me how close a certain circuit is to representing a certain function.

For example, if I need to implement a XOR function, than a circuit consisting of a single OR gate will be closer to representing the XOR in comparison to a circuit consisting of a single AND gate (because all is missing is a single NOT gate).

Are there any such heuristics in order to sense how "close" a circuit is to the final circuit?

We have tried scoring the circuits by counting the number of correct outputs according to the truth table, but this fails. For example, if we have a circuit that for every input outputs the negation of the correct output, then its "score" would be 0 according to this heuristic, but in fact it is very close to the final design, and all that is missing is to not the output.

Thanks


texts:
Is there a theoretical performance limit for Lithium Ion batteries? I'd like to compare energy density of Petroleum Products based upon what limits can be obtained from stored energy in Lithium Ion.
I'm thinking something analogous to the Rankine Cycle for Steam Engines.


texts: Why is my NAND not working with a load attached to it?

texts: I am designing a simple circuit where I want to use the output of one NAND as the input to a NOT gate. I have implemented both the gates using CMOS (NOT with 2 MOSFETs and NAND with 4 MOSFETs). Both of my gates are working fine separately. But when I combine them and give a square wave as an input the output is very weird. I am new to this and am just trying to figure out things. Can anyone please tell me what am I doing wrong?


texts: Hi I am doing a home project to make a simple calculator. I plan on using a encoder for the number and arithmetic inputs and I want to display it on an LCD. I plan on having a 16:4 encoder where 0 to 9 would be my numbers and 10 to 14 would be +, -, *, /, and =, respectively, The problem is I am unsure of how to get the LCD to take this binary numbers and display the corresponding character. I have been trying to google binary to ASCii converter/decoder and search it on texas instruments but to no avail. Is there a specific why to do this? Thanks


texts: Orientation of Loop Antenna (receiving mode)

texts:
I have done some measurements through a loop antenna similar to that shown in the following picture (all the informations included do not refer to my antenna, it is a picture used only to show its geometry):

My professor has told me that this antenna was sensitive to the electric field orthogonal to the surface of the loop.

So I have the following questions:

is this true for any loop antenna? Or does it depend on the specific model I use?
how can I understand which is the direction of electric field which is "catched" by an antenna? I thought to use the radiation pattern, but then I thought that it refers to how it catches power, while I want some informations about the electric field.


texts: Bi-directional electronic switch for external circuitry

texts:
I am in the process of designing a PCB that is powered by a 10V / 1mA supply from a fandeck (incorporating EC/DC fan motors).

One of the functionalities include having continuity between 2 pins on the PCB  (Volt free contacts), which are connected to an external controller (Master). Since the supply can only supply 1mA, I am using 2 n-channel Mosfets for their high input resistance. However, I don't know how to switch them since they're connected to an external circuitry with different voltage references (grouds), and the mosfet switching works around the gate to source voltage (Vgs(Threshold)).

One idea I had was to connect the Mosfet sources together and put a 1nF cap to ground so the voltage from the MCU would be with reference to both sources of the mosfets.

I also saw the attached picture in an application note from Texas Instruments (Application Report SLVA948–December2017), But I don't have any prior experience with charg pumps and am a little bit worried regarding their current draw and I also don't know the voltages that master controller might exert to check continuity so i don't know how higher the voltage should be when fed into the gates.

One other thing that comes to mind is just connecting one of the contacts to ground (PCB ground), However I am not certain this would work either.

I am already familiar with gate drive design so that is not an issue. Is there a better way of doing this with less current draw?
any help would be highly appreciated.

Many thanks in advance for your time.


texts:
I have a buck regulator (say the TPS82085) which I would like to use to regulate a 5V supply to various values ranging from 1.2V to 3.3V. It seems that a DAC is a good way to do it (I initially thought of using a resistor network since I only need to adjust it in 300mV steps but then realized I was just building a large, crappy and expensive 3-bit DAC). This is the feedback circuit I envision:

simulate this circuit – Schematic created using CircuitLab

My goal is to make it so that if I set the DAC to 0V, then I would have a 3.3V output, and if I set the DAC to 3.3V (its maximum value as it will be supplied by a 3.3V rail) then I would have a 1.2V output. The point is to make sure the downstream voltage cannot exceed 3.3V (or go below 1.2V) should the DAC be misconfigured by software. Also it gives my DAC maximum resolution.

From what I know, regulators with a feedback pin try to adjust Vout until the voltage at the feedback pin is equal to some reference voltage inside the device. For this regulator, the reference voltage is 0.8V.

By applying Kirchhoff's laws to the circuit, the voltage at the FB pin can be found to be given by

$$V_{FB} = \frac{R_2 R_3 V_\mathrm{out} + R_1 R_3 V_\mathrm{DAC}}{R_2 R_3 + R_1 R_2 + R_1 R_3}$$

So if the regulator works to force that to 0.8V, the steady-state operation of the regulator obeys

$$V_\mathrm{out} = 0.8V \left [ 1 + \frac{R_1}{R_3} + \frac{R_1}{R_2} \right ] - \frac{R_1}{R_2} V_\mathrm{DAC}$$

If I add the constraints that Vdac = 0V implies Vout = 3.3V and Vdac = 3.3V implies Vout = 1.2V then one can solve the resulting system of equations to find that the solutions are of the form

$$R_2 = 1.571429 \cdot R_1$$
$$R_3 = 0.401826 \cdot R_1$$

So for instance R1 = 100K, R2 = ~157K, R3 = ~40K would achieve the intended effect, as would any multiple of those values.

My question therefore is, is this a standard way to use a DAC to adjust regulator output voltage, and are those the calculations I should be making to find correct resistor values? Or are there additional factors that I should be taking into account? (other than resistor tolerances and Vref min/max values of course)

Maybe it's a good idea to account for the DAC output becoming high-impedance somehow? (Vout = 2.8V in this eventuality)


texts:
I have a question. Is it a good way to measuring 4-20mA with differential ADC?
Assume that we have a ADC with 2 single ended inputs or 1 differential input. Input A+ is the first input and input A- is the last input. If we connect a 4-20mA sensor to A+ and a resistor between A+ and GND so we get a pressure drop just to convert mA to Voltage.
Then on A- we do voltage dividing so we get the same input voltage as the sensor gives us at 4mA. Assume that we get 0.2V at 4mA from the sensor. When A+ and A- have 0.2V, then our ADC value is 0. When we have 20mA from the sensor, then our ADC shows maximum value.
Is this a good strategy?
Or should I use single ended ADC instead and accept that my ADC value will be a little bit higher because 4mA causes voltage input? So instead of the start ADC value will be 0, then we have e.g about 500 ADC value at start.


texts: Point of contact with a capacitor plate & rolled design?

texts:
With a simple parallel plate design for a capacitor, does point of contact(to the external circuit) matter?

I imagine any point(a - e) would yield the same feature in storing/discharging charge. However, I'm curious if there is an optimal point of contact relative to to it's performance.

In addition, if I were to wrap these two plates parallel to one another to conserve some space, if I had the point of contact at (a) and wrapped the ends such that point(e) meets the point of contact(a) with a gap in-between would it function as normally?


texts: Phase noise reduction in LC oscillator with a high-loss capacitor

texts:
I`ve got a capacitive vibration probe whose base capacitance may vary from 4 to 10 pF due to manufacturing/installation tolerances, whereas vibrations it detects can only alter its capacitance in sub-pF range.

To translate capacitance into voltage I`m using an LC oscillator, since the probe is so constructed that one of its sides must be grounded and also the circuit must be insensitive to EMI. As a consequence, RC oscillators and capacitance to digital converters cannot be used.

The problem is, I want to get as little phase noise as possible with a lossy probe. I`ve got decent results with Vackář and Lampkin topologies but I want to go further. I`ve found an active Q-enhancement technique for inductors (see here) but I need to enhance the Q of the capacitor, not the inductor.

I`ve also found out that coupled resonators can reduce phase noise (see here) but I seem to be unable to find any examples of practical oscillators with coupled LC resonators except for the microstrip ones. I`ve made an attempt to design an oscillator with coupled LC resonators using this technique but it turned out to require relatively high value capacitors while I need to keep Δf/ΔC ratio as high as possible, so that didn`t work either.

Please help.


texts: How to change the frequency for Motor 50 to 60HZ operation

texts:
Dears,

We received a 50 Hz 5.5KW 220V Motor, How to change this to operate in 60HZ.


texts: FT232h ACBUS 8/9 not working as TX&RXLED# in MPSSE mode

texts:
I use an FT232H in MPSSE mode and tried to use ACBUS8 and/or ACBUS9 as TX&RXLED# output.
I populated the EEPROM and programmed pins ACBUS8 and ACBUS9 as TX&RXLED# output.

As long as I use the chip in serial mode, ACBUS8 and ACBUS9 works as TX&RXLED# outputs as described in data sheet.

Unfortunately when software switches FT232H to MPSSE mode, ACBUS8 and/or ACBUS9 will not work any longer as TX&RXLED# output.

Any ideas how to use ACBUS8 and/or ACBUS9 in MPSSE mode as TX&RXLED# outputs?

Btw. in MPSSE mode the ACBUS8 and ACBUS9 pins can't be used as GPIO.


texts: USB OTG port in slave mode, possible to use USB-A ports in host mode simultaneously?

texts:
I have been researching USB OTG for a little while and was not able to find an answer to my question. I'm seeking for the conditions, if it's even possible, under which I can have one USB OTG port work in slave mode and at least one USB-A port act as host simultaneously. It is definitely not possible when the two ports are connected to the same USB Hub (e.g. like it is the case with a RPi Zero + Zero4U), but how about when the two ports are entirely separate? Here you can find a 'USB Map' of the Orange PI Plus2:

Could I use the USB OTG port, which originates from USB0, as slave port while, at the same time, using one of the Hub ports connected to USB1 in host mode?

Thank you in advance for your time and for sharing your experiences!


texts:
I need some help with the layout of a power supply. I botched the first two iterations as I do not have the necessary experience, and I would like to avoid another costly run.

For the sake of completeness, here is the previous (related) question:
Noise problem with buck/boost switching regulator

My device is powered by a Lithium-Ion battery, but needs an operating voltage of 3.3V. Thus, Vin = 2.7-4.2V, Vout = 3.3V. I decided to use a LTC3536 buck/boost switching regulator: http://cds.linear.com/docs/en/datasheet/3536fa.pdf

I basically used the reference implementation (page 1 of the datasheet) for a 1A/3.3V power supply. Here are the schematics:

There are three separate ground planes: PGND, coming from the battery and connecting to the LTC3536; GND, the signal ground which branches off from pin 3, and AGND, used for analog sensors etc which branches of from the GND plane.

This is the latest version of the 2-layer board. Red is top, blue is bottom layer. It's quite close to LT's demo board. I annotated the different ground planes, as well as VBATT and VCC.

Design considerations

I tried to adhere the recommendations that I found in the datasheet and the answers I got on the previous question. I use 3 different ground planes as described above, connected in a single point using a 0 Ohm resistor. I tried to use a star-like approach for routing VCC. AVCC is connected to VCC using a 0 Ohm resistor.

Questions

One of the problems with the previous design was that I connected the exposed pad of U3 using vias at the side of the chip. This required a lot of space. I now realized that LT added on their demo board the vias directly under the exposed pad. I didn't know that this is possible - do I need to do something special to these vias?
I am quite unsure regarding the placement of the ground planes. At the moment, the GND plane tees off from pin 2/3, and is connected to the AGND and PGND plane using a 0 Ohm resistor. Placement of this resistor is kind of random atm.
The whole circuit is switched using a MAX16054 soft power-on/off IC, which connects to SHDN of U3 (pin 10). The MAX16054 is connected to VBATT and GND (not PGND). Might this cause problems?

Any comments would be greatly appreciated!


texts: What to do with the excess of energy from a solar off grid system?

texts:
I have an off grid solar system and I'm playing with it with a Raspberry Pi and an Arduino.
I'm looking for an automatic usage of the 12V power produced when the battery is full. (The Arduino has a sensor for voltage and my Raspberry is ready to do activate/deactivate with relays.)
Here are some ideas I had :

Use a water pump to store water as potential energy 6 meters high and convert it later to power with a water turbine. (Seems really inefficient and too much investment into nothing.)

Use Peltier systems to convert electricity into water for later usage. (Dehumidifier) - Didn't try yet.

What do people do usually ?  I can't sell it back to the grid, I'm not connected to it.


texts: How do I change the frequency of an rf module?

texts:
I recently bought an AM radio transmitter/receiver from eBay.

It was only after I bought it, however, that I noticed that the frequency was 315/433 MHz. I live in the UK so only 433 MHz would be legal for my use. At the bottom of the eBay page it says that I can set the frequency. How do I go about doing so. Thanks in advance, I've never used radio communications before.


texts:
I tested for charging a mobile using SMPS, it charges the battery 10% percent in an hour. But when I connect the same mobile to the mobile charger it charges the battery 40% in an hour.

The SMPS input and output ratings are

IN  100 - 240V AC
    0.23A, 50-60Hz
OUT  5V DC /2000mA.

Charger input and output ratings are

IN  100 - 240V AC
     0.35A, 50-60Hz
OUT  5V DC /2000mA.

What is the reason for slow charging in SMPS..?

And Can I make fast charging using any additional circuits for SMPS?


texts: Determine the relative postion of a Chip to another one

texts:
For a project I want to have an unspecified amount of modules connected to each other. All of them will be controlled via a Controller. I would like to create a virtual map within the Controller, of the position of the modules relative to other ones. As you can the in the Image below, Chips 1-4 are connected  in a circle, which could obviously pose a problem, where signals are read multiple times and commands could run in a loop. Best case would be to get a X, Y Coordiante Map relative to the controller. (Chip1 = 0|1, Chip3 = 1|1 and so on...)
All of this will be done to mimic Nanoleaf RGB panels (Website and a Teardown), that create a Virtual Map of the Panels to play lighting scenes. I just can't figure out how I would be able to create such map and the teardown didn't went deep enough into that or I atleast was unable to understand it, but they made some findings like:

For the topology discovery, they use the EDGE pin. While VBUS is UART half-duplex broadcast, EDGE is a simple level signal, purely point-to-point used only doing discovery. As they walk down the tree structure to discover it, they basically turn on one EDGE pin on an unexplored branch of the tree, then through the VBUS ask whichever tile is seeing EDGE=1 to respond. From that, they get a unique tile ID (factory programmed I believe), then use this to assign a short ID to that tile, so they can talk to it later. Then they keep going.

But I wasn't able to make anything out of that, because my technical understanding of such circuits isn't too great.
My modules will be hexagonal (6 Ports) but this should work similar.


texts: How to get rid of voltage spikes in this supply voltage switcher circuit?

texts:
In my mainboard there are two main supply.
One is 12V and other one is 5V.

5V is always ON but there is a risk of 12V crashing and disappearing. So, I want something like this, when presence of 12V main supply always has to be 12V but when it is gone main supply must be 5V which is always ON. The crudial thing here is main supply must never be below 4.8V.

I used to get this done by this simple structure:

simulate this circuit – Schematic created using CircuitLab

But my client does not want that. Diodes get hot and there is a certain voltage drop. So I thought of this soltion:

It is doing its job but it can not prevent this annoying spikes:

You see, when both rising and falling of 12V, it leads a spike and it causes to voltage drop below 5V. I want to understand why does it happen? And is there any circuit that can do the job with high efficiency?


texts: When to use thermal relief and when not to

texts:
I'm working on a charger circuit which basically works as a buck-converter. I'm pouring my components with copper planes.

However as some of the components are connect to a large ground plane on bottom layer I suspect the best choice is to use thermal relief to ease soldering. However, should I do the same on the top SMD components?

I know there is pros and cons using thermal relief, but when should it be used and when not?

See below for the layout described above


texts: Determining parity or FEC (Forward Error Correction) requirements from percent error

texts:
I am very new to signal processing and my background is in physics. I would like to know if it is possible to determine the number of parity bits needs to theoretically get 100% transmission from a transmission channel with known percent error. Over a given transmission 25-30% of the transmission is incorrect.  This 25-30% represent the symbol error rate.  I am using a 8 level amplitude modulation scheme.

Is it possible to know with say a Reed-Solomon technique how many parity bits I would need to add to each block to move in the neighborhood of 100%?

I am processing my signal using MATLAB right now.  I am not sure if the EE stack exchange is the proper location for this.  If it is off topic I will close the question but I thought you all might have some knowledge in this area.

EDIT

I have been asking around and reading more and it looks like I could over come a great deal of error by using a RS code with a msg of 3 symbols and 6 parity symbols.  Is this correct?


texts:
I am trying to program a PIC32mx110F016B with a PICkit 3 with the "Power target circuit from Pickit3" enabled at 3.25V.

When I am trying to program this small code

#ifdef __XC32
#include <xc.h>          /* Defines special funciton registers, CP0 regs  */
#endif

#include <plib.h>           /* Include to use PIC32 peripheral libraries           */
#include <stdint.h>         /* For uint32_t definition                        */
#include <stdbool.h>        /* For true/false definition                      */

#include "system.h"         /* System funct/params, like osc/periph config    */
#include "user.h"           /* User funct/params, such as InitApp             */
#pragma config   FNOSC = FRC
#pragma config   FPBDIV = DIV_1 // Peripheral Clock divisor

int32_t main(void)
{
while(1)
{
}
}

it gives me this error message:

Target detected

Unable to connect to the target device.
Failed to get Device ID

This is the schematic I have done


texts: Unable to understand Drone's LiPo battery capacity loss

texts:
I have ruined a 3S LiPo 5400 mAh and I am unable to understand the reason. This is directly related to my earlier question which was about same battery.

I bought a new balance charger and put the battery on Balance charge on 3.5 Amps. When the battery was fully charged I checked its voltage with a Uni-T voltmeter and each cell was showing 4.3V when the charger was showing 4.2.

Battery was not hot, its temperature was being report as 25C and it did not puff at all.

I always try to take all the necessary precautions, and when I noticed that the battery is over-voltaged I immediately put it under some load (1/4th of normal) to drain the battery and reduce the voltage.

After some time it was within reasonable limits. This supposed overcharge remained for about 20 minutes.

Long story short, when i recharged the battery with another charger and then put the battery to use all the capacity was gone. 25 Minutes flight time was reduced to 5 minutes all in one day.

The internal resistance of cells as being reported by 2 chargers is not too high. 9mΩ  6mΩ and 5mΩ

I am wondering what happened? Is one time overcharge enough to ruin a perfectly normal battery? I know the battery is gone, but i want to learn from this so i can use the future ones better.

Everyone on internet keeps talking about low voltage but not really over voltage packs so i'm asking here.

This battery Never went under-voltage. Under load the cells at worst went to 3.6V

When I recharge the battery it reaches 12.6 Fine, and the charger reports as having provided 2700 mAh to it after starting at 11.1 V

What happened? Is the cause Lithium Plating? I want to learn lessons from this.

The numbers supposedly make sense, but the sudden discharge doesn't. As soon as you put the battery under load it instantly drops Voltage. on 1/3rd of the standard load it behaves like a perfectly fine battery.

The only other variable is that the temperatures have dropped recently due to winters. Now outdoor temperature is 11C and on last good flight it was around 25C


texts:
I am going through datasheet of TXKTPCSANF-32.000000. I require a clipped sine-wave TCXO with 1.8 Vpp maximum. However, the datasheet of the TCXO doesn't state the maximum Vpp. They have mentioned 0.8Vpp as minimum.

Find the screenshot of the datesheet below:

Am I missing something? Is there any standard to calculate max vpp of the TCXO? Or I assume it is the Vdd supplied to the TCXO?

EDIT:

We have part with 3.3V in stock. I am not sure if I can use the part with RF Front-end (SX1257). Is it possible that 3.3V variant of the TCXO may output less than 1.8 Vpp?


texts: Can the microcontroller program flash memory be used for storing user configuration?

texts: Many microcontrollers, e.g. PIC18F, have flash program memory: "The Flash program memory is readable and writable during normal operation". Does this mean I can store some user configurations in the program memory?


texts:
I was reading this sparkfun article to learn more about how transistors work, but I am confused by one of their diagrams. Here it is:

If there is no current flowing, why is there a 1.3V drop across the LED? I looked at the VI characteristic graph for LEDs and it should be 0v when I=0, which is the case here. I think I am missing something, can someone point out exactly what?

Thanks!


texts:
I saw the following circuit in an electronics exam. I think the feedback network consists of a transistor (M3) and a resistor (Rf) and the feedback type is current-current; Is this analysis correct?

I'm interested to know whether this feedback type has any applications in real life circuits.

simulate this circuit – Schematic created using CircuitLab

Edit: The first circuit had a mistake which now is corrected. I've drawn the initial circuit with 2 CS stages.


texts:
I have bought a 46ft power boat and it has a bow thruster installed, however the 24v motor has been removed and all of the other parts are missing, that is wiring , relays , control buttons etc.

The motor for the thruster is 24 v x 8000 watts vertical mount.  I don't know what the rpm of the motor is and I have not tried to run it either so I don't know if it is good or not.  I suspect it is u/s.

I have starting batteries that meet the specs for the motor but 8000 watts is 333 amps which is a massive draw on my batteries and requires a cable run of 10 meters (30 ft) from batteries to the thruster in the bow.

To buy all the missing gear presuming the motor is good will cost big time, you know what marine equipment costs are like.

I am thinking about replacing the existing motor with a 240v single phase motor with a reversing switch which will be much more cost effective and leave my start batteries unmolested. I have a 16kva single phase genset on board so power is not a problem.

So the question is what will the specs be for the replacement motor?

Will the wattage of the 240 motor be the same?

I calculate that would be a 8hp 240v electric motor. I have been talking to one of the bow thruster suppliers and they are not willing to help out with a conversion so am asking for some help here on getting the right 240v motor that will match the specs of the 24v motor.

Can anyone estimate the RPM of the 24v motor?

Can anyone foresee any problems with the concept?

Thanks.


texts: I want to understand this audio input to LED output simple circuit

texts:
I'm a newbie in electronics. I watched a youtube video that showed how to activate LEDs using a microphone. It's project #3 at https://youtu.be/zsJ61yJhWVU?t=115
The guy built the circuit on camera but did not explain its working. He did flash a circuit diagram (which I'm attaching here too).
I roughly get the point of this circuit but want to understand it completely.
a. I understand that two back-to-back amplifiers are needed to achieve good amplification. Correct?
b. I understand that capacitor is used at the base of the first transistor because audio input is not a DC (constant) signal but a time-varying analog signal. But why is it necessary? What will happen if we remove the capacitor at the input.
c. Why he has used two different transistors? (One is C945 and other is BC547)
d. If I build this circuit with two 2N3904, will it work ?
e. Why isn't there some resistance at the collector-to-emitter path of the second transistor (to me it looks like a short circuit and the transistor will be damaged).
f. Is there a way to build a circuit that converts audio input to LED output just like this circuit, but with even fewer components. (I want to start with simple and then understand why we need more components so that I can fully grasp the concept and practice).


texts: If an electronic device specifies an operating RANGE between 6~15 volt with 210mA current, can you use a 9 volt battery to power it?

texts:
I have a FrSKY QX7 digital telemetry radio system (radio transmitter) and on its' specification it says

Operating Voltage Range: 6~15V (2S, 3S Lips are acceptable)
Operating Current: 210mA maximum (both RF module and backlit are on)

The thing didn't ship with a battery and I'm just trying to use it for a drone simulator- so if this doesn't work, i have to wait for a battery to get here and that's not fun.
I have a 9v battery, cables, and the battery that will eventually plug into this has a 2 prong connector into the circuit board.
So if i take a 9 volt battery, add wires to it, connect those two wires to the two prongs right there... based on the above stated operating voltage range, will it... work without damaging the unit?
It's a temporary hack, I just don't know enough about electronics to determine how bad of an idea it is. Thoughts? Ideas? Other solutions? Resources that dumb people like me can understand?


texts:
I'm currently building a DC-DC step up circuit to step up 3V to 100V. I don't want to use transformer because i want to keep the circuit as small as possible. My thought is ... building a 30V-output circuit using MIC2250, then build a boost circuit to boost the voltage 3-4 times. The 30V output has been achieved, but the boost doesn't work. The diagram is as below.

I was thinking of repeating this circuit 2 to 3 times in order to step up the overall voltage 2-3 times. but it doesn't work.

My another design is to use IC solely. some ICs like LT3757 and LT3783 seem to fit my design, but I just don't find any suggested circuit to boost from 3V to 100V. I tried MCP1652 before by following the circuit in the datasheet. Although the datasheet clams that the circuit can step up the input to 100V, I just can't do it. The maximum I got was only 40V.(I emailed the technician from MCP...he asked me to find the solution on the internet myself...poor aftersale service...) the only suggested circuit from 5V to 350V in LT3757 requires transformer, but i just try to avoid transformer.

Can any body share you idea with me about the circuit stepping up from 3V to 100V? Iout = 0.1A will be good enough. slightly smaller will be acceptable too.


texts: Are the AND-OR and OR-AND forms of combinations exactly sum-of-products and product-of-sums?

texts:
Are "the AND-OR forms of combinations" and "sum-of-products"  exactly the same?
Are "the OR-AND forms of combinations" and "product-of-sums"  exactly the same?
In "the AND-OR and OR-AND forms of combinations", is single NOT gate  applied only to literals?
In "sum-of-products and product-of-sums", is single NOT gate applied only to literals?
Thanks.

The terminology comes from Mano's Digital Design:
The sum-of-products and product-of-sums are mentioned in Section 2.6    Canonical and Standard Forms in Chapter 2    Boolean Algebra and Logic Gates,

and are simplified   in Section 3.2    The Karnaugh Map Method   and  in Section 3.4    Product-of-Sums Simplification.
The AND-OR and OR-AND forms of combinations are mentioned in Section 3.7  Other Two-Level Implementations in Chapter 3    Gate-Level Minimization.

The types of gates most often found in integrated circuits are NAND and NOR gates.
For this reason, NAND and NOR logic implementations are the most important from
a practical point of view. Some (but not all) NAND or NOR gates allow the possibility
of a wire connection between the outputs of two gates to provide a specific logic func-
tion. This type of logic is called  wired logic.

and


texts:
I asked this question on StackOverflow and was told it was more suited to here...

I am getting started using the micro:bit and have just built the micro:bit piano mentioned here: https://www.youtube.com/watch?v=ulKq5To9dmA

I want to get my students to make it in school as a project but I have a few questions about how the circuit works.

The power-supply and earth are both taken off the micro:bit. The 3.3v passes through a 22mOhm resistance in the circuit on the video (and a 100kOhm resistance in my circuit). A wire is inserted between the resistance on the breadboard and the pin from the micro:bit . When this wire is connected to ground (the Piano key and Earth on the diagram), depending on which pin it interrupts, the micro:bit plays a sound.

The questions I have are:

In the code, the GPIO pins are set to a floating state at the start. Would it be safer to set the pins to 1 at the start or would this stop the circuit from working? I don’t know if there is a risk of a stray voltage damaging the board if the pins are in a floating state?

pins.setPull(DigitalPin.P8, PinPullMode.PullNone)
pins.setPull(DigitalPin.P12, PinPullMode.PullNone)
pins.setPull(DigitalPin.P13, PinPullMode.PullNone)
pins.setPull(DigitalPin.P14, PinPullMode.PullNone)
pins.setPull(DigitalPin.P15, PinPullMode.PullNone)
pins.setPull(DigitalPin.P16, PinPullMode.PullNone)

I don’t have a 22megaohm resistor so I used a 100 kilohm resistor, and a stick made of some insulated copper wire in place of my hands to connect the piano key to the ground. I know that you should not connect the 3.3 volt directly to ground on the micro:bit as it my damage it. Is a 100kilohm resistance enough to have between the 3.3 volt supply and the input pins or is there a risk this could also damage the micro:bit? It is putting 33 microamps into the pins.

Thanks for your help.


texts: What the R value to this operational amplifier isn't saturated?

texts:
In the following circuit, the three ideal operational amplifiers are polarized such that their saturation voltages are ± 20 VDC. The other components of the circuit are resistors, one of them being adjustable (the Rx).

What is the limit condition for adjusting Rx so that the output voltage does not saturate?

A) 3kΩ < Rx < 4 kΩ.
B) Rx > 5 kΩ.
C) Rx < 5 kΩ.
D) 4 kΩ < Rx < 5 kΩ.
E) Rx < 4 kΩ.

My attempt:

Consider \$V_{down}\$ and \$V_{up}\$ the voltage on Buffers inputs are \$\frac{40}{3}V\$ and \$\frac{20}{R_x + 1}V\$ respectively.

So the Summing Amplifier is:

$$V_{out} = -2k\left(\frac{\frac{20}{R_x+1}}{1k}+\frac{\frac{40}{3}}{2k}\right)$$

Consider that \$V_{out} \leq -20V\$ (I'm not for sure this statement)

$$-20 \geq -2k\left(\frac{\frac{20}{R_x+1}}{1k}+\frac{\frac{40}{3}}{2k}\right)\Rightarrow 10 \leq \frac{20}{Rx+1}+\frac{20}{3}\Rightarrow \frac{1}{Rx+1}+\frac{1}{3} \geq \frac{1}{2}\\
\frac{6}{Rx+1}+2 \geq 3\Rightarrow 6\geq R_x+1\Rightarrow R_x \leq 5k\Omega$$

I find the letter C) but the correct answer is letter B).

What did I miss?


texts: Homemade EVSE require UL/CSA/Other certification for insurance?

texts:
In general, would an insurance company require a homemade electric vehicle charger to be approved by some recognized agency such as CSA or UL? I am in Canada.
I have designed and built a few electric vehicle chargers that I would like to give to my friends and family as the cost is MUCH much less than an equivalent commercial charger.
My worry is that, since it's not certified, an insurance company would refuse to pay out in the event of a fire whether or not the charger was the cause.
At the scale I am producing these things (may never make more than 10 in my life) it's obviously ridiculous to think of paying the 50K+ for a certification.
Before you go telling me off for how dangerous this sounds, I'll have you know that I am perfectly qualified to design and build this type of device, I just don't have the means to certify it.


texts: Can a 9 volt battery through your bloodstream kill you?

texts:
I usually try to do some research before asking questions on this site, but everything I've found has been contradictory.

If I were to direct the positive and negative ends of a 9 volt battery through open wounds on either of my hands, allowing the electricity to travel through my bloodstream and presumably past my heart, would it kill me? What if I were able to let go as soon as I felt the shock?


texts: XS-3868 module stops noise for 5 seconds, how to make it longer

texts:
I've made a bluetooth audio receiver using XS-3868 module (using this diagram) and connected a TP4056 charger module and a lithium-ion battery too. Everything works fine.

When the charger module is powered (using its micro-usb port), there is no noise as long as something is being played. But when the music stops, the speakers become silent, then after exactly 5 seconds a merely loud noise starts. If another song is started the noise stops. Even if I change the volume on my phone, to which the module responds by a small beep sound, the noise stops again for another 5 seconds.

Of course there is no noise if the charger is not powered and the module is on battery.

I can somehow understand the reason for noise when charger is powered (although I don't know how to fix it, and any help would be great), but my main question here is:

If the XS-3868 can stop the noise, how can I tell it to keep doing the good job, and not give in to the noise? I could not find anything about this feature in XS-3868 properties, or how to prolong that 5 seconds.

Edit 1: I just found the same question here and tried adding the capacitor mentioned there. The noise got much louder! Somebody explained it this way: "The OVc3860 audio output is differential. So If You connect it to amplifier You should do this as differential input. In fact on AGND of OVC3860 is avarange 0.6 V." I have no clue what that means.

Edit 2: I tried adding the resistor according to this too. No difference.

Edit 3: I just found a curious bridge between pin 17 and 18 of the OVC3860. I don't know if it is intended or I should try removing it! Here is a photo:

.


texts:
I am trying to incorporate a TEC in a portable system.  The heat from the interior of the system needs to be transfered to the exterior where it can be dissipated freely into the environment. Now, I have developed a thermal management design where heat is conducted outside via sheets of copper and will be ultimately deposited into a fabricated "water heatsink" where temperature differential is mitigated by water's high specific heat capacity and additional surface area. The water heatsink is consisted of coppersheets forming a thin container filled with water. The system needs to be compact and lightweight and this system seems to provide heat mitigation capabilities and an increased surface area.

Attached is the visual illustration of the design. Is this viable?


texts:
I'm no engineer and hence the reason for posting... I'd like to make the smallest possible powered LED unit I can - that also has some sort of on/off switch included. I have a space limitation of about 5mm x 5mm (it's a cylindrical piece of plastic). I'd like to NOT have a protruding switch of any sort to turn it on/off. So, I was thinking of the possibility of using a magnetic switch or something.

Can anyone give me input/advice? I would think with all of the nano-tech that's starting to roll out, it should be feasible. I definitely know the LED wouldn't be the size issue, as I've received samples from KingBright that you can almost not even see on a counter top!


texts: Why does this AC-DC converter have Live and Neutral inputs specified?

texts:
I'm using this AC-DC converter (120VAC-5VDC) as a power source for an Arduino-based device.

https://www.digikey.com/product-detail/en/recom-power/RAC01-05SGA/945-3043-ND/6677085

The AC-DC converter has input pins labeled Neutral and Live. I'm wondering how essential it is to get the polarity right. A quick test showed no difference, and since the output 5VDC is totally isolated, it doesn't seem like it should be affected by the input polarity.

Does anyone know why these are labeled specifically, instead of just "AC in"?


texts: Finding the Thevenin Equivalent Resistance

texts:
In this problem I'm trying to find the Thevenin resistance in the circuit below:

simulate this circuit – Schematic created using CircuitLab

The first thing we do is remove all sources and the load resistor. So now we have the following circuit:

simulate this circuit

The part I'm stuck on is computing the total resistance between the load terminals a and b. If I remove R4, I can figure it out; R2, R7, and R8 all terminate at the ground node. We have R2 and R7 in parallel, which is in series with R5, which is in parallel with R8. Thinking of it this way, but then adding R4 into the mix, doesn't R4 begin and end at the same node?


texts: Arduino analog input value oscillating, why does the DMM work and arduino not so much

texts:
I am measuring voltage output from a device with 10 kohm output impedance with an arduino analog input pin. I see what I would expect with a multimeter, but with the arduino I get either garbage, or at best, oscillating measurements that average out to about what I would expect.
I know the impedance of the analog pins to be 100 Mohms, while on the DMM, it would be around 10 Mohms, so I wasn't expecting the Arduino to be useless while the DMM works fine.
I finally found that shorting the outputs with a capacitor gives me what I'm expecting, but don't really understand why. Resistors helped but I still saw oscillation, and I assumed, being an issue seemingly with impedance, that resistance mismatch was the culprit.


texts: I need help understanding the dynamics of this oscillator

texts:
I'm a beginner at circuits (I'm a high school student interested in electronics), and I'm currently working on a school project about a Magnetostriction Oscillator. The circuit construction is as follows, and I need some help understanding certain aspects of the same.

So from my understanding, the circuit working is as follows:

When the battery is attached a voltage V is supplied to the LC oscillator. Which induces an oscillating flux in the rod: A question I had is that since its a DC supply, won't the capacitor saturate after the time constant is completed, making the induced magnetic field constant (all current directed through L1)
The apparently oscillating magnetic field in the rod induces an EMF in L2 - which gets amplified through the BJT and gets fed back into the parallel LC oscillator (is this why it acts as an AC voltage allowing the parallel LC to oscillate??): I get the induced EMF (provided magnetic field is oscillating) - but don't get the amplification. Won't the induced emf/current get amplified and move towards the reference ground node instead of the LC oscillator?? If it does could you please explain why?
Any additional help on understanding how the LC circuit oscillates and how the transistor plays a role in the same would be much appreciated!

Thanks a lot!!


texts: LM386 amplifier buzz when not connected to signal

texts:
I've set up a simple LM386 amplifier on a breadboard according to the above schematic. When connected, the amplifier works like a charm driving a spare 8Ω speaker with impressively low (audible) noise.

On the input (pin 3) I'm connecting just the left channel of a 3.5mm audio jack.

When no source is connected to the jack and the power is switched on I get a significant buzz coming from the amplifier, which is worsened when a 3.5mm audio cable is plugged in. However, as soon as I connect the other end of the cable to a source (phone/MP3 player etc.) the buzz stops completely.

I assume this is a grounding issue and that I'm essentially making a big aerial the moment I connect an unterminated cable. This is inconvenient as there might well be times when the amplifier is switched on but a source isn't hooked up.

Question: Why does this happen, and how do I prevent noise/buzz when no source is connected to the input?


texts: Switch 15V source with a MOS by digital 0/5V (dc)

texts:
I'm trying to switch on and off some 15V devices from Arduino Uno digital ports (0/5V). Each port must control a group of resistive loads (lights) of a train model. There are about 10 groups of loads, and I'd like to keep simple the switching circuits. From now on I'll consider just a switching unit, a group of lights.

I want the power source (VDC) to lit my lights as much as possible when the digital port is high (5V) and let them off when it's low (0V).

My first attempt has been to use a common MOSFET, the 2N7000, with a pull-down resistor to force the lights to turn off and secure the transistor in case the load gets accidentally disconnected. R1 is high-valued compared to the load, so most of the current flows to the load, and the threshold Vgs of 2N7000 is around 2V; it looks like 5V should switch it on. I decided that each load would be composed up to 10 lights, 1'5k Ohm each, so that the 150 Ohm equivalent R would drain 100mA from VDC, below the 200mA maximum Id for the MOSFET. All grounds are common.

simulate this circuit – Schematic created using CircuitLab

So this was my short study. However, once in the field, the lights weren't that bright, and after doing some theoretical tests, I got around 3V at output node instead of the expected ~14V from power source (VDC - Vds_on)

After searching online, I found that this transistor may not be appropriate for this job, although I wouldn't consider it a "power electronics" job. I have to add that I don't need a high switching frequency; maybe about 100Hz for a software-ruled PWM fade-on/off effect, but nothing else.

Question time (most important first):

How can I get the 14V at output?
Is 2N7000 inappropriate (and why)? Which [family of] transistor could I use instead?
Do you think the circuit is alright? Could you recommend me some securing mechanism (current) for the Arduino side?

Thank you very much!


texts:
Working in an electronics lab, we do micro soldering and I came across the tool pictured. No Idea what it's is for. I'm guessing its some tool for holding or removing chips as you rework a PCB. I don't even know what to call it (forked flat plate tweezers?) so looking around got me a lot of cosmetic tweezers and normal component handling but I can't seem to find this shape.

Can anyone help?

It's not a major issue just a nice to know if someone else knows.


texts: How many concurrent senders can CDMA support for a code length of n?

texts: I understand how CDMA works (kind of). I'm just not sure how to go about figuring out how many orthogonal signals can be produced from a code length of a given number.


texts: Switching of RS485 differential line. Two sources, one output

texts:
I'm looking for a solution for my project.

I have two signal sources (primary source and secondary source) on the RS485 (A/B) differential line. When/if something goes wrong on the primary, then I switch over the button switches to the secondary source.

Which electric component could I use for switching the differential line (other than a relay)?


texts:
I'm doing some research on what types of LCD displays can be used to filter and pass UV light for resin curing - specifically in the context of building a DIY 3D SLA printer.

The community commonly uses the Sharp LS055R1SX03 module. Looking through the datasheet, there doesn't seem to be any information pertaining to the characteristics of the device when passing UV wavelengths. Is there something special about this module that allows it to filter/pass UV wavelengths compared to other common LCD displays?


texts: What is this wire to board connector called?

texts:
I'm looking for the correct terminology of the connector in the pictures below, which, as far as I understand, serves to connect unstriped wires pretty easily to some form of socket. I encountered it in a washing machine. I tried googling and going through a distributor's online catalog, but I'm not getting far without the correct jargon.

The first two pictures show the connector opened up. The metal pieces serve as both connection pin for the socket and to pierce trough the protective layer of the wires which have to be pushed trough the top holes. I suspect that first the wires are pushed trough the holes, then the metal pins are placed, and finally the whole is closed.

The last two pictures show the connector when assembled.

Edit:
To further clarify the use of the connector. It is used on the thermostat / thermistor of the the dryer in the machine.


texts: How to improve emitter-follower efficiency?

texts:
I’m trying to wrap my head around the emitter follower.
I’m currently using it to simulate a ~12V AC coming from a intercom ringer (about 700Hz).

simulate this circuit – Schematic created using CircuitLab
My input is a function generator and I would like my output to drive quite a bit of current. Right now the best I could do is drive a few mA but in the process I’m setting my \$R_E\$ on fire.
Is there a way to improve the efficiency of this circuit? Or I’m better off using another buffer?


texts: Altium : How to design a width rule for a subset of a net?

texts:
On my current design, I want to set a width rule for some nets which provide power in order to get them fatter. I set a net class on the net,set a rule and it works pretty well.
Now, this net is also used as an input on a ADC pin of a microcontroler. The first thing is that I don't need a fat connector for this purpose, the second is that there's no way to connect a fat line to only one pin of the microcontroler.
Is there a way to exclude a part of the net class from the rule ? Or a specific rule but based on which information ?
Here are two screenshots for illustration purposes.


texts: I have converted a vw bus to 112 VDC electric drive (Tesla battery modules 22.5VDC X 5 ea). There is also a 12V system for lights and instruments. The BMS supports SPI and CAN. I have no experience with either of these protocols but I am using SPI for the BMS. I have also heard of Android Automotive. I want to add a Tesla style tablet display, cameras, and proximity sensors and have expandibility. What are the pros and cons of vehicle network protocols? Can you point me to examples to learn from?


texts: Trying to get a 32.768 kHz crystal to oscillate

texts:
I've spent quite a bit of time read up on oscillator circuits and trying to get this circuit to oscillate. I'm trying to build this oscillator for a clock but I won't be putting it into a RTC, so I only need the 32.768 kHz frequency as an output.

Rereading, I'm pretty sure I need 25 pF caps instead as I misinterpreted how load capacitance worked. Regardless, I've tried a few different cap values (which were not 25 pF) and have gotten nothing.

I've also tried swapping and removing the resistors to a number of values as well.

However, I don't know what else is wrong. Moreover, I want to simulate it in LTspice but I don't know how to get the motional parameters as I only know the motional resistance.

I've also tried building this circuit on a breadboard and I get nothing but a flat line on my oscilloscope.

The crystal I'm using is a CFS-206 HZFB and the datasheet is here:
http://cfd.citizen.co.jp/english/prod-tech/product/pdf/datasheet_TF/CFS-206_CFS-145_E.pdf

Thank you in advance for any help with this.


texts:
I'm using an ac coupled noise matching transformer to measure the voltage noise of a low ohmic sample as a function of bias current. The complete circuit is in an enshielded enclosure. When the transformer primary is fully floating (without R2), the circuit is quite susceptible to external noise. The circuit is shown below

simulate this circuit – Schematic created using CircuitLab

However when a high value resistor to ground (R2) is connected to the primary, the pickup drops significantly.

Why is that?


texts: Vacuum tube systems in apollo era space missions

texts:
I hope this is the right place to ask this. But my friend is just learning about electronics and just was given an old vacuum tube. Just because I'm curious, is there any technical information on the computer systems used for the apollo space missions? (Not a system diagram, just an overall summary). Specifically, I was just curious as to the number of vacuum tubes used in both the apollo spacecraft as well as the mission control computers.

I'd just like a high level description if possible. I'm an EE grad but I'm explaining transistors and digital electronic systems to my friend who's not an Engineer, but is a bio researcher.


texts: Is it safe to drive P-channel MOSFET gate directly from an MCU pin and 12V pull-up?

texts:
I was wondering how reliable it would be to drive a P-channel MOSFET directly from a micro-controller pin like this:

simulate this circuit – Schematic created using CircuitLab

When I want the FET to be ON I make the pin output low (connecting the gate to the ground).
When I want the FET to be OFF I make the pin input (high impedance), pulling the gate to 12V through R1.
The only problem I see is that when OFF, the MCU pin will "see" 12V through R1, but I am thinking it shouldn't really be a problem, since R1 is quite high and the impedance of the pin itself is much higher, so there shouldn't really be any danger for the pin. Or am I wrong?
Obviously, we're not talking high switching speeds here, just turning stuff on and off from an MCU.
I know it is usually done with a BJT or N-channel MOSFET acting as "gate driver" for the P-channel MOSFET. The question is, what will go wrong if I try to skip it?
I don't have a specific MCU in mind, could be an ATTiny monitoring the input voltage and deciding whether or not to pass it to the rest of the circuit or an ESP8266 turning stuff on and off over the internet and whatnot.


texts:
I want to measure weights with arduino. After the measurements, i want to analyze the weight data of the measured objects.Precision is not very important, but it should be work in the range of 10 to 100 kilograms.

Is there a force-sensing socket, weight-sensor or something similar for Arduino that i can use?


texts:
I'm making a small device that I want to power by the sata power connector/ATX PSU. It needs 5v and 12v power supply. This device will use standard 15pin SATA power male connector to get the power from the PSU. According to the specs I found here, there are 3 5v and 3 12v pins, some of them are longer and used for precharging. My question - is it ok in the device to shorten all 5v together to get more power, and also the same for 12v and ground? I suppose so because on all my PSUs there's just one wire comes to the SATA power connector for each voltage, but is it standard and stated somewhere in the specs?

Also, there are power disable and Staggered spinup/activity pins - can they just be ignored?

Thank you.


texts: The basic 6T structure used for storing data is same as one used in "Positive Feedback Differential Voltage Sense Amplifier", then how come while the data is stored in SRAM memory cell it doesn't get amplified?


texts:
Why is the frequency of the response same as that of the forcing function in a linear circuit?
What's the case when the circuit isn't linear?


texts: Voltages decreasing while using the 6 and half multimeter

texts:
I am using this this desktop Multimeter - 6 and half multimeter
Whenever I measure a voltage or current in the auto mode, the last three digits continues to decrease and keeps on decreasing till the fourth digit also decreases.
For example, if I measure a diode drop to be +0.805919V at time t=0, it goes from that value to +0.805900V... +0.805851V....+805230V........+0.804780.. and goes so on. This happens around 5minutes.
Why does this happen?
I am measuring at only +25degC


texts:
I have developed and built a tangentially tracking tone arm for playing LP vinyl records. Its carriage is driven by a 15 mm diameter stepping motor.
Mechanical design is easy for me, however, now I'm in need of a VCO to produce a square wave from 0.2 Hz to 27.0 Hz to drive the stepping motor driver which I bought from Sparkfun. I found a 555 timer based VCO on the internet that works but it does not give me the frequency spread mentioned above. The input to the VCO comes from the amplified output of a linear analog Hall Effect sensor.
Could someone help with the design of the required VCO?

Hello to all above who have responded to my question from 2013.
I am in shock because I was not aware that there had been any answers.
Thank you very much.

I have been improving the tone arm since 2013 to where the required servo has become much simpler. I will be asking questions about that in the next few days.

In 1984 I patented the idea of using a stepper motor to drive a tangential tone arm, and let me assure you that it worked flawlessly.

"Gearing" the tone arm to the rotation of the turn table platter will not work, because the grooves on an LP don't have the same pitch from groove to groove.

Sincerely,

Ralf


texts: Smartphone microphone frequency response, ADC and SNR

texts:
I'm trying to find on the web if there's an example of smartphone that records with low quality (which introduces lot of background noise) and an example of phone that records with good quality, maybe with the frequency response, snr and the characteristics of the ADC.

For now I have found not so much (especially on the ADC), all that I have found is old.

Can someone help me? Thanks in advance.


texts:
I need to be able to solder wires to the hidden pins of an smt ic. The ic is soldered directly to the pcb, and they are not visible. I need to access the PCM audio interface on a sim7500e, and the only way to do that would be for me to solder wires to the pcb, then resolder the sim7500e. Does anyone know how to do this? For reference, here is the prototyping module I am using.

Thank you for any help


texts: Understanding Power/Current/Voltage drawn by LED Strips

texts:
I am trying to create a LED lamp which will be powered up by a battery. Lets assume I want it to run the lamp for 1hr. My LED Strips operate at 12V with 19.2W/M. I am using around 1.7 Meters(198 LEDs) of LED strips.The strip uses L2835 Type SMD LEDs.

So the LOAD here will be operating at 12V with Power of 33W and a current of 2.75A will be required.
The battery I am using is 18650 with 3.7V and 3.3A

I attempted few of the approaches to calculate the load current and volt but could not understand what was happening exactly.

Approach 1

Connected a DC-DC step up buck converter(XL6009) with heat sink to the battery to boost the voltage to 12V
Measured the voltage/current with and w/o LOAD and the reading is as below

w/o LOAD Voltage across battery  is 3.57V
w/o LOAD buck conv o/p voltage tuned to 13.37V
there was no initial current drawn.

After connecting to the LOAD, the reading is as below
Voltage across battery reduced is 2.96V
current draw from battery to buck 1.43A
buck conv o/p voltage reduced to 9.4V
current draw from buck to load is 0.4A

Approach 2

I thought most of the current from battery is being utilized by buck conv to boost up the voltage from 3.5 to 12V so connected three 18650 battery in series and made it as input to buck.

Measured the voltage/current with and w/o LOAD and the reading is as below
w/o LOAD Voltage across battery is 10.58V
w/o LOAD buck conv o/p voltage tuned to 12.53V
there was no initial current drawn.

After connecting to the LOAD, the reading is as below
Voltage across battery  is 10.17V
current draw from battery to buck 2.43A
buck conv o/p voltage reduced to 12.47V
current draw from buck to load is 1.12A

Even in this case, there was a slight voltage drop.
After 10mins of continuous running, the buck converter heated up and it gave a output voltage of 1.5V

Approach 3

So the last approach I did was to connect the battery directly to my lamp and got the reading as below
w/o LOAD Voltage across battery is 10.58V, there was no initial current drawn.
After connecting to the LOAD, the reading is as below
Voltage across battery  is 10.58V
current draw from battery to load 0.7A

Questions

In Approach-1 -> Why did the voltage reduced? Is it because the LOAD needed more current and  not available ? But my Battery can sufficiently provide 3.3A against 2.75A which is required.
In Approach-2 -> The XL6009 is  60V 4A Switching  Buck-Boost converter, I would like understand why it got fried, when the load is drawing 1.12A?
In all the approaches -> As per the current calculation (I=W/V) which is will be drawn by the load (2.75A) is not been actually drawn, rather we could see lesser current been drawn at the Load? (Per multimeter readings)
Is it the problem with battery configuration. What would be the ideal suggestion with respect to battery source if i need to run the above load for 4 hours.

Kindly help me in the regard. Let me know if any other inputs are required


texts:
I need to configure the CAN module of a STM32F207 to the following different baud rates: 500 kbit/s, 600 kbit/s, 700 kbit/s, and 1 Mbit/s. For 500 kbit/s and 1 Mbit/s I am able to get exact integer values for the following registers.

Prescaler = 2 (CAN Controller's clocked @ 30 MHz)
BS1 Timequanta = 8
BS2 Timequanta = 6

But when I do the calculation for 600 kbit/s, I am not able to get integer values for the above mentioned registers.

Is it not possible to arrive at the exact register values for the baud rates 600 kbit/s, 700 kbit/s, etc.?


texts: Proper resistor(s) for limiting LED brightness

texts: I have an LED powered by a serial(Rs-232) port on my PVR. The light is connected to the DTR pin through a 1k\$\Omega\$ resistor. It is set up this way in accordance with the instructions for the software controlling the light.  However, I find the light to be too bright and am wondering what the best approach would be to dim the light's brightness. I am not overly experienced in the field of LEDs, resistors, and diodes, but I am assuming a larger resistor (or set of resistors) or diode would drop the current, reducing the brightness. I just do not know which size resistor(s) or diodes to use.  I cannot provide specifications for the LED itself, as it is a part from an old set-top box without documentation.


texts: Resources for learning how TFT works and how to drive it at the glass level?

texts:
I just scavenged an TFT display from a digital picture frame. Using the number on the back of the panel, I was able to locate and download the data sheet.

I read through the document hoping to drive it using rows and columns using a Microcontroller, but I am stumped by the terminology and concepts,

Other online and offline resources all discuss how to drive the display using a specialized, dedicated interface chip. Are there any resources that discuss how a TFT works and how to interface with it at the "glass root level"? I am assuming they all operate similarly and have similar hardware interfaces.


texts: How would I test the continuity of an anti-static wrist band?

texts:
I am looking to purchase some anti-static gear for when working on electronics(I'm assuming all electronics should be worked with on an anti-static pad, that's correctly grounded, correct?), and noticed in some reviews there are mention of not having "Continuity" in the strap they purchased.

One review mentions

  WARNING FOR PURCHASERS AND ALL BRANDS OF A COMPUTER ANTI-STATIC WRIST STRAP –
  Before beginning my PC build, and looking at this $400 motherboard, from a past experience, I decided to verify that the Rosewill ESD Anti-Static wrist Strap will actually work, by testing it with my Multi meter.
  The Results were stunning - THERE IS NO CONTINUITY (CONNECTION) FROM THE ALLIGATOR CLIP TO THE METAL PAD ON THE WRIST STRAP – THIS NO STATIC PROTECTION!

  So this brings a couple questions:
  1) Is the bad connection just on the wrist strap I just bought, or on a whole bunch.
  2) How many people buy any brand of anti-static wrist straps, put it on and think they are protected, then for their electrical part go bad thinking they were protected!!

  Worse yet, most everything Nowadays is cheap China Stuff (CCS) and it is really hard for a company to make sure China/Asian products have quality.

I had randomly learned about continuity(right before reading this review), from a video of a water damaged iphone.  The user used a multi-meter while connecting 1 side to something (couldn't see in the video), and would test both sides of the capacitor to see if it would beep.  If both sides beeped, it seemed to be a bad capacitor, but if only one side beeped, that means it was good.

So I'm curious about,

If the information presented in the video is true, and if so what exactly is going on there with the beeps and why it should only beep on one side?
What exactly am I trying to test, and where, on the anti-static wrist band?  The definition of continuity mentions "Continuous flow" so would I test the 2 ends, and multiple parts of the wire if something goes wrong, or...?

Any information about continuity testing, and any information about the subject in electronics, or some guidance to reading materials would be greatly appreciated, thanks.

EDIT:  Review was from https://www.amazon.com/Rosewill-Anti-Static-Components-RTK-002-Yellow/product-reviews/B004N8ZQKY/ref=cm_cr_dp_synop?ie=UTF8&reviewerType=all_reviews&showViewpoints=0&sortBy=recent#R2LY6BRSK3A4UN

The segment is from 26 mins or so on this video https://www.youtube.com/watch?v=plmElKA6qKM&list=PLtjsWVbfWwk6cIQEN4aWjIiaP4VgXYuB0&index=3

Sorry share isn't working so I cannot get it directly at the timestamp.


texts: Mosfet based constant current source, and the mosfet gets too hot

texts:
I have constant current source circuit as follow:

The mosfet chosen is: Fairchild Semiconductor FCH072N60F (Q1, Q2 are identical).

For anyone questioning the 500 Ohm gate resistance: I have to increase gate resistance to dampen MOSFET ringing (it gets pretty bad when Rg < 100).

My ultimate purpose is to generate a sinusoidal constant current (with Vpeak/2 DC offset) with this circuit. But for now, I use a 10V Vgs, 5A DC current for the sake of thermal analysis (input of the op amp is 5V DC). The phenomenon is the MOSFET is much hotter than the series resistance (R26). I think this suggests that Rds of the MOSFET are higher than 1 Ohm, which is not possible because the datasheet states that Rds = 0.06 Ohm to 0.07 ohm when Vgs = 10V.

I guess that the gate resistance Rg has something to do with this but changing Rg didn't help.


texts:
architecture RTL of design is

    signal input : integer range 0 to 16777216 := 0 ;
     ....

begin

    -- VHDL entity instantiations
    -- named association, instead of positional

    input_stage: ENTITY work.input_stage

        port map(
            ...
            input => input

        );

    filter: ENTITY work.filter

        port map (
            input => input,
--          ...

        );

end architecture RTL;

The error: value -2147483648 for input is out of range 0 to 16777216.

So it looks like I can't override the default value. Is that possible?


texts: What could be the intent of the designer who made this? As far as I understand, if Vcc = 35V, when MOSFET is ON, actuator_sense pin goes to zero. When the MOSFET is OFF, the resistance L1 and R25 are in parallel. So by resistor divider formula, we get a voltage across R27, or actuator_sense pin. I think the designer only wants to know if L1 is present or not? Right?


texts: Effect on current due to relative motion of load in homopolar generator

texts:
Description of figure -
A homopolar generator in which disc is rotating with constant angular frequency with respect to ground frame and a uniform steady magnetic field is present perpendicular to disc plane .
I wanted to understand what will be effect on current through load due to relative motion of load in two cases (below) for homopolar generator and in general any generator.
Question-
Is current through loadZ (figure)  same in following cases?
1.a brush is attached(fig) to circumstances of disc whose velocity (of brush not disc)with respect to ground frame is zero and then load is connected to a that brush and axel(center).
2.if load is  directly connected between axel(center) and circumference of disc without brush i.e load is also rotating with same velocity as disc.
I thought current should be same in both cases but I'm not sure because we mostly read in books only 1st case is mentioned almost in every book but not 2nd case.
hope  someone can help me !


texts: Unwanted oscillations and distortions in buck converter

texts:
I've tried today to design a very simple and crude 26V to ~12V buck converter. But after testing it in LTspice I've got some weird and unexplained oscillations and distortions. The oscillations produced on 'Q1E' then distorted the signal of the oscillator.

Here's the picture:

The green oscillations had a frequency of about 21MHz which it then "mirrored" to the base of Q1. Also the frequency of the 'OSC' had decreased from expected 640kHz to 410kHz and the duty cycle has increased.

If I increase L1 to about 100uH the oscillations are gone and the circuit works as expected. The 'OSC' and 'Q1E' frequency then becomes around 640kHz with a 50% duty cycle.

Why does this happen? The LC resonant frequency of L1 and C6 is only around 16kHz. Does L1 form a resonant circuit with some other capacitor (Q1-BE,D4)?

Is there a way to get rid of the oscillations without increasing L1 to much? I could add a resistor between 'Q1E' and L1 but that would defeat the whole purpose of buck converter.


texts: How to calculate the orientation of a IMU sensor?

texts:
With a BLE CPro sensor I'm trying to "build" a remote control for a smartphone game. How can I recognise the orientation (pref. grads) of the sensor if it is on the left or right without being affected by their gravity. i.e. in a shaken/moving environment?

My problem is that if I calculate the orientation using the accelerometer, every time the sensor is being shaken the gravity changes drastically which makes it difficult to know the current orientation.

This CPro sensor offers an example on how to calculate their quaternions. As an output it shows a cube graphic using OpenGL ES which follows the orientation/rotation of the sensor. Unfortunately I’m not quite understanding how can I get from the quaternions the orientation in grads…

//src https://github.com/mbientlab-projects/iOSSensorFusion/tree/master
- (void)performKalmanUpdate
{
    [self.estimator readAccel:self.accelData
                        rates:self.gyroData
                        field:self.magnetometerData];

    if (self.estimator.compassCalibrated && self.estimator.gyroCalibrated)
    {
        auto q = self.estimator.eskf->getState();
        auto g = self.estimator.eskf->getAPred();

        auto a = self.accelData;
        auto w = self.gyroData;

        auto mp = self.estimator.eskf->getMPred();
        auto m = self.estimator.eskf->getMMeas();

        _s->qvals[0] = q.a();
        _s->qvals[1] = q.b();
        _s->qvals[2] = q.c();
        _s->qvals[3] = q.d();

        //  calculate un-filtered angles
        float ay = -a.y;
        if (ay < -1.0f) {
            ay = -1.0f;
        } else if (ay > 1.0f) {
            ay = 1.0f;
        }
        _s->ang[1] = std::atan2(-a.x, -a.z);
        _s->ang[0] = std::asin(-ay);
        _s->ang[2] = std::atan2(m(1), m(0)); //  hack: using the filtered cos/theta to tilt-compensate here

        //  send transform to render view
        auto R = q.to_matrix();

        GLKMatrix4 trans = GLKMatrix4Identity;
        auto M = GLKMatrix4MakeAndTranspose(R(0,0), R(0,1), R(0,2), 0.0f,
                                            R(1,0), R(1,1), R(1,2), 0.0f,
                                            R(2,0), R(2,1), R(2,2), 0.0f,
                                            0.0f, 0.0f, 0.0f, 1.0f);

        trans = GLKMatrix4Multiply(trans, M);
        self.renderVC.cubeOrientation = trans;
    }
}


texts: How to amplify current and buffer voltage

texts:
I have a battery supplying 5V@500mAh and an LED (the load) which draws 1000mA@5V (twice the current the battery supplies per hour).

I found some circuits that have NPN transistors only and other having Op-Amp and a MOSFET (for example How to design Current Amplifier circuit to amplify the signal current to 1A).

Can someone draw a circuit that can handle this boosting job?

And please in order to understand it more deeply, tell me why do I need an Op-Amp when using a MOSFET as an amplifier?


texts: Can this scheme be used to balance an unbalanced output transducer?

texts:
If we want to create fully differential and balanced outputs, and if we don’t have a single ended to differential ended converter/driver, can we use the following scheme neglecting the voltage divider DC errors?:

The idea is to create same common mode noise at HI and LO nodes. VCM is the source model for the common mode interference capacitively coupling to the lines. Vs is the desired signal source.

Since the device inside the green box  inherently does not have balanced outputs, can balancing be achieved by using a potentiometer R2 on the diagram?

Did anybody use this scheme before? Im wondering whether is a proper method.

In simulations the idea works but I don't know in practice would be issue:


texts:
For my Electronics II class, I designed a discrete BJT amplifier circuit including a VGain, Buffer, and Power stage.

I succeeded in meeting the specs, and the next step is to improve our design in one of a few specific ways. I chose to improve the power output of my circuit. My plan has been to build two amplifier channels and bridge them.

To do so, I have added an inverter and a second buffer stage to the second channel. Currently I have the circuit set up in CircuitLab, and it simulates satisfactorily. The circuit is attached, along with a plot of the output.

My question is two fold.

The first arises because when the channels weren't balanced, I was getting an ever increasing static voltage at the output. I want to be able to tie the output to ground if possible. I found that adding a 1H inductor could do so, but I don't want to add a 1H (LOL) inductor to the output. Is this circuit safe to build, will I see real results like my simulation, and is there any way I can tie my output to ground so the DC offset is 0V?

Two, do you have any recommendations to decrease distortion, or increase power?


texts:
I read in the datasheet of this PCB relay, that the relay has high switching reliability due to crown contacts.
What mean crown contacts ?


texts: Help identifying 1.25mm pin pitch, 15-pin connector (crimped)

texts:
Please help identifying this connector:

measured pin pitch: 1.25mm (17.5mm/14); may also be 1.27mm
15 pin (female), single row
crimp connectors
1.5mm width (thickness)

photos of the socket:


texts:
I am using TIM1 to drive a DMA channel which is sending bytes to GPIOF on an STM32F407. TIM1 is started by an OC channel on a different timer. In the DMA stream interrupt handler, I am attempting to stop TIM1 and also reset the counter by generating an Update event. For troubleshooting purposes I have configured an OC channel on TIM1 so I can confirm it is starting and stopping as expected.

It does appear to start and stop at the correct times when viewing the pin output using a logic analyzer, but when stepping through the interrupt handler in the debugger I see that the CEN bit is still set after clearing it. Also, TIM1->CNT continues to increment as I step through each line.

The interrupt handler is as follows:

void __attribute__((interrupt("IRQ"))) DMA2_Stream5_IRQHandler(void)
{
    // Clear interrupt flags
    do
    {
        DMA2->HIFCR = DMA_HIFCR_CTCIF5 | DMA_HIFCR_CHTIF5;
    }
    while(DMA2->HISR & DMA_HISR_TCIF5);

    // Stop TIM1, TIM5 will re-enable it
    //TIM1->CR1 &= (u16)~TIM_CR1_CEN;
    do
    {
        TIM1->CR1 &= (u16)~TIM_CR1_CEN;
    }
    while(TIM1->CR1 & TIM_CR1_CEN);
    TIM1->EGR = TIM_EventSource_Update;     // Trigger an Update to reset the counter

    // Re-enable DMA for next TIM5 event
    DMA2_Stream5->CR |= DMA_SxCR_EN;
}

The code does exit the loop which clears CEN, but afterwards viewing the TIM1 registers shows CEN is still set. How can I ensure the timer is really stopped and will start counting from 0 next time it is started?


texts: Do all Solid State Relays function as diodes?

texts: I just installed a solid state relay as the main power switch for a robot I'm working on.  The robot is controlled by a Windows 8 tablet and I thought it would be cool to use the tablet to turn the bot on and off.  Not long after I started using the relay I realized that the battery wasn't charging (the charger was installed after the relay).  Once I connected the charger directly to the battery it started charging - this means that the relay was acting as a large diode.  Is this an effect of all Solid State Relays?  If so, this could be a very large problem for some applications.


texts: Can I use a Ku band satellite dish for Wi-Fi?

texts:
Satellite TV works at 18-24Ghz and WiFi  at 2.4Ghz, will a T.V dish antenna work for WiFi?

Diameter of the dish is about 60-90cm


texts: Can you argue the current decrease along the two inductor pieces of a transformer using impedance?

texts:
I'm looking for a way to explain it other than using energy conservation/ power equal logic.

in this we derive the relation between current in each coil by equating powers and then using the ratio of voltages from faraday's law. Now, would there be any way to show the current change without Faraday law/ an intuitive perspective of it?


texts: Can a resistor mitigate a maximum input voltage limitation?

texts:
I have a microcontroller running at 5v and outputting a digital signal. This signal can be high, low or high-impedance (tristated).
This signal goes to an input pin on a target chip (the type of which is not known in advance), which may be running at 3.3v or at 5v. Therefore, I need some way to limit the "high" signal to the VCC of the target.
Ordinarily, I would use a level shifter, but they don't support tristate. I could use a tristate buffer, but that's a whole extra chip - not to mention the extra control pin.
Could I use a resistor?
I may be wrong, but I believe the "maximum input voltage" limitation on chips is due to current - often current through an internal protection diode. If I used a 10K resistor, surely so little current would flow into the input as to represent no danger to the target?
It did occur to me to use a resistor AND a diode to VCC, thus limiting the voltage to VCC+0.6v.....but might this cause issues with the tristating?
EDIT: Added diagram for resistor + diode. Would this work? Or would it cause issues with the tristating?

Only problem I can think of is, in the absence of target VCC, it will be supplied a 4.4V VCC from the signal. So I would need to avoid setting the signal high when the target didn't have power applied. Am I right?
EDIT: Clarification:
I think perhaps some of you are misunderstanding the question. The output signal (at 5V, 0V or floating) has to be safe (and a valid high/low/hi-z) for all 5V and 3.3V targets, which are likely to be microcontrollers. Will my resistor-and-diode solution work? Or, will just a 10K resistor work?


texts: Designing a low-cost, low-performance UHF RFID antenna 902 - 928 MHz

texts:
I use UHF RFID readers to read Gen2 RFID tags. Here's the reader I use but it could be any equivalent reader configured to run at 902 - 928 MHz. https://www.digikey.com/product-detail/en/thingmagic-a-jadak-brand/M6E-MICRO/1523-1004-ND/4842688

For a new project, I want to read tags under a 30 foot long bench (athletes have Gen2 tags on their ankles and I want to determine who is sitting at the bench). I only need a 2ft read range.

Off-the-shelf RFID antennas are so small that I would need a large number of them to cover a 30foot length of bench. I could probably do it with 16 antennas and two 8-port splitters it's pretty clunky and expensive though.

So my question is, could I create long, cheap antennas by fixing wires to a plastic backing, similar construction to an electric blanket. I imagine I'd need two wires running in parallel to one another, a specific distance apart and maybe some capacitors bridging the two wires. It would be ok if the antennas were quite inefficient as the reader I use is quite powerful and the range I need is quite small.

Not sure where to start on the design of the antenna though. I haven't been able to find designs for UHF RFID antennas yet.

really appreciate any guidance on this!


texts: At what point will I start having trouble with noise and parasitic capacitance/inductance when using standard 0.1in header pins? If I'm using an MCU capable of driving a 20MHz SPI bus, would it be reasonable to run a breakout board or Arduino shield at that speed? I will be using either the ST NUCLEO-F446RE or the NUCLEO-F303K8 development board.


texts:
If you try to obtain a voltage greater than the power rails of an op-amp, what will happen?

I am assuming that the output == the rail limiting it. Is that correct, or does it break the op-amp?


texts: Connecting led fairy lights together powered by ac mains

texts:
Iv a set of fairy lights, Rated Voltage 3v, 15mA, I would like to connect four sets together in series (12v 60ma).I can get uk ac/dc 12V 1A Power.
Question1 : Do i need to connect a resistor if so what one.
Question2 :Is 12 volts enough.
Any advice would be appreciated


texts: Logic Analyzer shows voltage change in analog but not digital

texts:
While using a logic analyzer with analog voltage to test Digital Output Pin voltages on an Arduino UNO, I am seeing the expected digital output and analog output (HIGHs and LOWs for digital and 5V to approx. 0V for Analog).

I'm using a Saleae logic 4 to test the digital output of an Arduino and an Arduino-compatible (Ruggeduino) for simple digital output. The Arduino seems to run my sketch just fine and the Saleae can read my output pin as both digital and analog. The moment, however, I drop the "Ruggeduino" in with the same sketch, my digital output seems to fail to work, and when I take another sample with the Saleae, my "Analog" voltage shows the highs and low voltages I'm expecting, but the "Digital" output is suspiciously blank.

Why would my logic analyzer show the expected digital and analog output when testing the Arduino Uno, but show a consistent "High" for digital output but both high and low voltages on the Analog output when testing the Ruggeduino?

Additional Information: Devices used:

Ruggeduino
Arduino UNO R3 from Arduino.cc
Saleae Logic 4

Edit: Not satisfied to just sit and wait for someone to answer, I did some more digging. Here's what I found out:

The logic appears "High" despite the change in voltage, looking as if it's stuck High
The Analog voltage of "Low" for the output pins appears to be 1.586V, which falls outside the range of TTL "LOW" (and most likely the cause of the "stuck" logic level)
This only happens when the pins are connected to the downstream input pins that should only be listening for digital output. Once you remove the downstream pins from the equation, the "LOW" voltage drops back down to just above 0V.

I don't currently have a screenshot handy to upload, but I can upload my sketch to show what I'm attempting to do:

void writeWiegand(String);
int outZeroPin = 6;
int outOnePin = 7;
int led = 13;

void setup() {
  pinMode(outZeroPin, OUTPUT);
  digitalWrite(outZeroPin, HIGH);
  pinMode(outOnePin, OUTPUT);
  digitalWrite(outOnePin, HIGH);
  Serial.begin(9600);
  delay(1000);

}

void loop() {
  String code = "0001001001100101100000001011010010";
  writeWiegand(code);
  delay(500);

}

void writeWiegand(String code) {
  for (int i = 0; i <= (code.length() - 1); i++) {

    if (code.charAt(i) == '0') {
      digitalWrite(outZeroPin, LOW);
      //delayMicroseconds(100);
      delay(100);
      digitalWrite(outZeroPin, HIGH);
      Serial.print(code.charAt(i));
    } else {
      digitalWrite(outOnePin, LOW);
      //delayMicroseconds(100);
      delay(100);
      digitalWrite(outOnePin, HIGH);
      Serial.print(code.charAt(i));
    }
    //delayMicroseconds(100);
    delay(100);
  }
  digitalWrite(led, LOW);
  Serial.println(" Output to Wiegand");
}

Edit 2: The downstream device is a proprietary Access Control Panel, and the input pins are pins  are for Wiegand communication with a card reader. Since it is proprietary, I'm not sure what I'm legally allowed to share. According to the manufacturer, the two input pins output 5V which the reader is supposed to Pull to ground to send information on either the "Zero" or "One" wire. The UNO R3 works fine for this task with the same code above. When pulling low with the Ruggeduino, there is still 1.586V left over, which I find confusing.


texts: How does a solar cell its relative thermal coefficient "alpha" expressed in 1/K relate to %/K?

texts:
Some times I see the relative thermal coefficient of solar cells Isc (called "alpha" or α) written as 1/K, other times as %/K.

I think that %/K can be seen as 0.01/K, but I am not sure.

Is it correct that 0.000555 1/K = 0.0555 %/K?

PS: absolute Isc,stc of the solar cell = 149.6 mA and I would like to output temperature compensated irradiance with formula:

G = (Isc,meas ÷ (1 + αIsc (Tcell-Tref))) × (Gref ÷ Isc,ref)

thus G = (Isc,meas ÷ (1 + αIsc (Tcell-25))) × (1000 ÷ 149.6)

I think that αIsc needs to be filled out here as 1/K (=%/K divided by 100) and not as %/K, otherwise the temperature correction seems too high.


texts: ARM Cortex reset button and debug interface (SWD)

texts:
I am designing a circuit using the EFM32ZG222 MCU (an ARM Cortex M0+) and I need to use the SWD interface (with a 10-pin Cortex Debug Connector) along with a reset button. I found a schematic that shows typical connections for the SWD interface:

The problem is that the pin named "RESETn" on the MCU is to be used both by the debug interface and a reset button. I am not sure that the debug interface can handle the discharge current from the 100 nF capacitor (see the schematic below).

I would like to know how use both a reset button and the debug interface at the same time.

Thanks in advance :-)


texts:
in fact i have several boards like Analog barrier, digital barrier, uart barrier and power control.
they are connected to together by RS485.
but some times when some of 485 don't work of the RX led remains on.
i don't know how solve this problem.
some times i have to change 485 ic  for five times.


texts:
If an op-amp or amplifier applies a gain to the input signal, does that mean it converts very low power signals into high power signals?

For example, a 741 op-amp has a gain of \$A_v = 10^5\$. That means it can convert a signal from a micro-volt range to a volt range.

Where does this power come from? How is this amplification possible? Doesn't it contradict basic laws of energy conservation?


texts: High Power LED Strobe making a Whining Noise when powered by a PWM signal

texts:
I am trying to control/fade a couple of High Power LEDs, these are basically 12V 18W LEDs inside a nice package.

I want to use an Arduino and a N-Channel MOSFET to adjust the brightness.

I tested the LEDs by directly driving them from a bench power supply and controlling the brightness by adjusting the voltage (between 0-12V) and it worked just fine.

I then moved on and used the N-Channel MOSFET to control the LEDs by setting an arduino PWM-pin to the Gate-pin. I am not at all an expert but I think that should do it and it indeed works.

Setting the PWM from the Arduino controls the MOSFETs Gate and adjusts the brightness but here is the strange thing that happens. The LEDs are constantly making a whining noise when I lower the PWM. Now the noise is actually not that bad but I am worried that the LEDs will eventually die out because something is certainly not right.

Any idea on what I am doing wrong? Please don't suggest that I should move on to other ways of driving these LEDs as I don't have access to much electronics.


texts:
I am currently dealing with current mirrors and came across the circuit shown below, a High-Swing Cascode Current Mirror. I read that this implementation, as the name suggests, has the advantage of a high voltage headroom, since the minimum potential at the drain terminal of M4 is:
$$
V_{D4\_min}=V_{DS4}+V_{DS2}=(V_{GS4}-V_{TH})+(V_{GS2}-V_{TH})
$$
So the drain potential at M4 only needs to be twice the overdrive voltage, in case of same transistor dimensions, in order to hold M2 and M4 in saturation. But cannot this be said for many other cascode current mirrors, since that behaviour simply occurs by "stacking" together two transistors (M2 and M4)? Additionally, why is there a connection from the gate of M1 to the drain of M3? I have a hard time understanding whats going on in this circuit, help is greatly appreciated.

EDIT:
A bias voltage source is setting the potential at the gate of M3/4. Sorry its not shown in the circuit.

EDIT 2: I just read that the mentioned bias voltage is implemented by a MOSFET in diode configuration, like here. For further discussion lets call it M5.


texts:
So i saw this schematics

i pretty much understood it all, the comparetors, the sensors, the variable resistors , but because i am a beginner i still dont understand some things.
1- why did he use a diode?
2- why did he use a capacitor?
3- why this 1 k resistor ( circled)
4-why all those crossed connections
5- why use  a power mosfet instead of a relay?


texts: Programming USB OTG PIC32 through USB in MPLAB

texts: I have a PIC32 that has USB OTG. How would I program it through a USB cable in MPLAB? Does it work out of the box of does it need additional software.


texts:
I want to build a variable gain amplifier.  My first thought was to build two feedback resistors and switch one or the other off with a MOSFET.  However, the MOSFETs have shunt diodes which are going to interfere.

There are thousands of MOSFETs on Avnet for example, and randomly selecting I see only models with the built-in shunt diodes.  Hoping someone can identify a keyword to pinpoint MOSFETs without diodes, or identify a different design that is better that what I am proposing.


texts: When do I include parasitic capacitances in a VLSI analysis?

texts: Each transistor in a current mirror I’m designing has internal capacitance (C_gs, C_gd, C_ds). Im trying to do an analysis by hand to find the transfer function, but I dont want to include all of the capacitors, because that would take so long to do. How do I know which to include?


texts:
I am currently trying to design a basic time delay circuit. The circuit's goal is to switch on a BLE beacon (requires 1.8V-3.6V at 1mA) for 3-5 seconds and then switch it off again. My first option was to use a 555 timer, however, due to the fact that the circuit is battery powered (coin cell CR2032) I require something which uses the least amount of power. I thus opted for an n-channel mosfet with a low-side transistor configuration.

Is this the best, most efficient manner in which I could build a delay circuit?
If not, what is and why is it more efficient?


texts: How do you reduce this simple system diagram for the sake of doing algebraic manipulation?

texts: My guess is that since H(s) is parallel with 1(s) we'd do A(H - 1)?  But this is my first diagram, so not sure.


texts: Using a FTDI to USB adapter with a raspberry pi and a roomba

texts: I'd like to control a Roomba 560 using its 8-pin mini din SCI port. I've seen other people do this successfully but I'm still unclear on how exactly to go about this. I was planning on using an USB to FTDI adapter, which is officially supported by the pi, and somehow wiring the pins to corresponding values. Would this cable work? And after getting it wired up, how would I control it?


texts: What is the purpose of solder mask expansion?

texts: I see recommendations of 2-4 mils for solder mask expansion.  But why is it necessary?


texts:
I'm currently re-designing a 12-layer pcb. The only thing I am still struggling with is the routing of the ethernet.

The layer stackup is as follows:

Top Layer
GND_1
MidLayer_1
PWR_1
MidLayer_2
GND_2
PWR_2
Midlayer_3
GND_3
Midlayer_4
PWR_3
Bottom Layer

I have read a lot of ethernet design guidelines which mostly stated that preferably the RJ45, Ethernet magnetics and Tx and Rx lines should have a ground keepout beneath them. Now here is my confusion I just read this paper: Ethernet Ground and it states

  When designing 4 layer boards, the ground plane should
  exist on layer 4, assuming the differential pair is routed on layer 1. On 2 layer boards, the ground
  plane can be located on layer 2, the adjacent layer to the TX and RX signal pairs. Under no
  circumstances should a ground plane exist under the magnetics, the RJ45 connector or in
  between the magnetics and RJ45 connector.

I find the part of "when designing 4 layer boards, the ground plane should exist on layer 4 (layers further away?)" and the "under no circumstances should a ground plane exist under the magnetics, the RJ45" very conflicting and would love some clarification.

TLDR Questions:

When following the rule of having a ground keepout around the ethernet, does this keepout have to be on all 12 layers. Or only the nearest adjacing layers?

PS: there are some related ethernet questions about layout, Stackexchange question but it doesn't completely satisfy the "why" part I am interested in and does not address the multilayer design.


texts: How to sense current being used by motors

texts:
I have an Arduino project that provides 12v power to run motors, etc...

I want to be able to measure the current (amps) that the motors are using (0 to 500ma). 12v comes from a battery, but that shouldn't matter. I just have a 12v circuit and I want to measure the current the motors are using (or 0 if they aren't using any).

I don't need a really accurate reading (+/- 30ma would be enough).

I can't use a premade sensor or shield.

I have read about using a shunt resistor and an op comparator (LM311), but I don't understand how I would do that, or if its even the current way to measure.


texts: AVR ATmega: can I trigger external interrupt by setting corresponding INTF flag bit?

texts:
I'm writing a C program for ATmega64A which has a INT0 ISR. This ISR should be executed in case of INT0 falling edge OR if the TIMER3 goes overflow.

To avoid doubling the code I'd like to trigger Int0 ISR in the Timer 3 overflow ISR.

Unfortunately there is no such information in the datasheet. At least in the INTF register description section:

Does anyone tries this? Or maybe someone knows this in theory?


texts: Turning on and off an output with just one button and a FlipFlop

texts: I am trying to make a circuit with the following characteristics: If I press the switch once and then immediately release the circuit activates the output and leaves it activated. If I press it again and release the button, it deactivates the output and leaves it disabled and so on. But in the circuit that I mounted (pictured below) the output is activated only while I hold the button pressed. Can anyone tell me what I might be missing?


texts: What type of method for producing White-Light LEDs is the most common?

texts:
There are two primary ways of producing white light-emitting diodes (WLEDs):

To use individual LEDs that emit three primary colors red, green, and blue and then mix all the colors to form white light.
To use a phosphor material to convert monochromatic light from a blue or UV LED to broad-spectrum white light, much in the same way a fluorescent light bulb works.

Which way is being used more in commercial applications, and why?