texts: Loss of pressure during sound propagation

texts:
I try to understand some things about acoustics and seems that I haven't understood many things.
Suppose that the sound pressure at mouth is p_lips and the sound pressure at a microphone that is located at a distance L from mouth is P_mic. Is there any way to compute P_lips, supposing that I know the rest two?
Does anyone know a relevant equation?


texts: Power rating of dual output isolated DC/DC converter

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I would like to use an isolated DC/DC converter SIP to generate 19 V from a 12 V input voltage for a gate drive application with approximately 1.2 W output power required. The isolation voltage should be 5.2 kV.
Looking at the Murata's DCDC catalog there seems to be no obvious solution. Choosing a slightly higher output voltage and using an additional linear regulator would be an option. For example, the MEJ2D1212SC could be used to generate +-12 V to generate 24 V essentially. However, this will cause quite some additional (possibly unnecessary) power dissipation in the linear regulator.
The actual question is regarding the MGJ2D121505SC with output voltages of +15 V and -5 V. Using this as a 20 V supply would be favorable. However, the specified output currents are relatively low compared to the 2 W power specification as can be seen here:

Is the power rating just a general approximation and the output currents are the meaningful data? When using this as a 20 V source, would I be limited to the 40 mA of "Output Current 2"?


texts: I want to find the period of a signal. On searching on the net, I found that the power spectrum density (PSD) can give an estimate of period, by finding the highest peak in the spectrum. However, there are many methods to estimate PSD. Some of the methods include welch, bartlett and periodogram. I am confused on which one to use to estimate the PSD. I also found that periodogram has good frequency resolution but is a bad estimator of PSD. Which among the above mentioned methods provides a balance between frequency resolution and estimate of PSD?


texts:
I'm using the MCP3421 to read voltages from thermocouples on battery power.

I would like to get this working over USB but I think the low common-mode range of the ADC could be problem so I am thinking about isolating the ADC from the USB micro.

It seems like the ISO1540 i2c isolator could isolate data so I would need an isolated way to power the ADC.

What are my options to supply an isolated few milliamps for the ADC and what impact would these have on the common-mode range?

Ideally I would like the solution to be as small and low cost as possible!


texts:
"Switching circuit"  is a concept opposed to logic circuits. Both are used for implementing digital circuits.
The first link says

From 1934 to 1936, NEC engineer Akira Nakashima published a series of papers showing that the two-valued Boolean algebra, which he discovered independently, can describe the operation of switching circuits.24 His work was later cited and elaborated on in Claude Shannon's seminal 1938 paper "A Symbolic Analysis of Relay and Switching Circuits".[4] The principles of Boolean algebra are applied to switches, providing mathematical tools for analysis and synthesis of any switching system.

The second link says

Electronic logic gates differ significantly from their relay-and-switch equivalents. They are much faster, consume much less power, and are much smaller (all by a factor of a million or more in most cases). Also, there is a fundamental structural difference. The switch circuit creates a continuous metallic path for current to flow (in either direction) between its input and its output. The semiconductor logic gate, on the other hand, acts as a high-gain voltage amplifier, which sinks a tiny current at its input and produces a low-impedance voltage at its output. It is not possible for current to flow between the output and the input of a semiconductor logic gate.

"Circuit switching" is a concept opposed to packet switching. Both are used in telecommunication and computer networks.
Are the two groups of concepts related?

Are "switching circuit" and "circuit switching" related?

Are "logic circuit" and "packet switching" related?

Is switching circuit  used for digital circuits, not analog circuits?
Is switching circuit  replaced by logic circuits, or does it have usages that is not replaceable by logic circuits?
Thanks.


texts: I have a 5v(coil) dpdt relay. Running it with 9v is safe or not? How can i reduce the voltage from 9v to 5v ? How much resistor i need ?(i do no want to use voltage regulator pls)


texts:
While researching 5G, I came across massive MIMO. Thing is to understand massive MIMO, I need to understand MIMO, which I am somewhat confused about.

First thing I'm confused about is the spatial multiplexing. I understand the base station can send two signals with the same frequency at the same time in multiple different directions and they won't interfere because they take different paths, but how do they not interfere when they reach the mobile? For instance, if my phone has two antennas, my phone is pretty small so how won't the signal interfere?

Under that question is another question. I read some stuff about signal vectors being orthogonal and such, but I have no idea what that means. What are the vectors? How are they orthogonal? Also don't understand the matrix \$H\$ or \$H^{-1}\$ is that's used to compute the CSI using pilot signals, very confused about all the equations I see.

Finally I'm kind of confused as to how the capacity is increased in MU-MIMO. Let's say I have 2 antennas at the base station and two users. Let's say transmitting each bit takes 1 millisecond. If I have 8 bits to transmit to each user, then using MIMO it will take me 4 milliseconds to transmit the data to user 1 (since each antenna sends 4 bits) and 4 milliseconds to transmit the data to user 2, so a total of 8 milliseconds. On the other hand, if I dedicated 1 antenna for user 1 and 1 antenna for user 2, it would still take me 8 milliseconds to transmit the data for both, and that's better because user 2 doesn't have to wait... so where is the increase?

Do you guys know any books or articles that explain massive MIMO comprehensively but also very easy to understand? Most of the stuff I read is very confusing. I'm only an undergrad ECE student, I have a hard time making sense of academic papers published about this topic.

Hope this is the right site to post these questions. Sorry if anything is not clear, I'll try to clear things up, and thanks in advance.


texts: LM3915 Circuit how to adjust input level?

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I have used the circuit diagram that is on page 2 of this datasheet and it works pretty much. I am getting the signal off the output of my computer which has been cut and then feed into my circuit and to the Logitech speakers I run my sound through.

I was wondering how and where would I introduce a part to change the sensitivity of the circuit. To make circuit light up more LED's with a lower signal level and vice-versa?

I'm also not sure that voltage of is the V+ that is I connect to the LEDs (top right of the diagram) is meant to be? I have connected it to 5V which is powering the whole circuit - do I need to place a resistor there to bring the voltage down for the LEDs?


texts: Can i use a PWM HHO Controller to control Brushless DC Motor?

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Hi im a electronics newbie.
The part im talking about is

DC 10-50v 12V 24V 48V 3000W 60A amps DC Motor Speed Control PWM HHO Controller

here is the link

My question is can this type of part be used to control brushless DC motors ?

Edit. Motor Specifications

24V, 320W, Brushless


texts:
I have two options to select system clock:

INTOSC
FOSC

I want to use the internal clock at 8/16 Mhz.

Which one should I select and what is the difference between FOSC and INTOSC?


texts:
I was checking RS485 signals with an oscilloscope and saw some waveforms which look distorted (see right side of image PIC1).

See schematic for test points TP1, TP2.

Setup

Probe 1:- TP2 and GND
Probe 2:- TP1 to GND
Oscilloscope Earth terminal was disconnected.

Channel Setting

Ch1 :- RS485+ (TP2)  Red Color
Ch2 :- RS485- (TP1) Yellow color
Math Ch2-Ch1 =  Green Color

Oscilloscope trace images

PIC1 : is the waveform when RS485 communication active and other device is connected.
PIC2 :- expanded view (zoom) of right side part of waveform PIC1
PIC3 :- expanded view (zoom) of left side part of waveform PIC1

Questions

Why is the amplitude changed on half of the waveform?
Has anyone seen this before?
Why does this only happen when the other RS485 device is connected at the opposite end?


texts:
This circuit controls the rate at which M1 switches on using the current mirror consisting of Q1 and Q2. A digital pot is used to control the current through Q2. The circuit works great in simulation, and it works semi-great on a breadboard.

The circuit yields a rising slew rate in the range of .3V/us to about .05V/us. Ideally I would like it to be able to switch at .7V/us.

The 3.3V is coming from a Raspberry Pi, however I have also tested it using a lab power supply. I am using the lab power supply for 12V VCC.

I have two questions:

How can I increase the rising slew rate of this circuit? I thought possibly using a logic level MOSFET would make it switch faster but it didn't help much.
Using a resistance range of 100-1000 ohms on R2 results in roughly the same slew rate. What could be causing this? I thought the Raspberry pi just couldn't supply enough current for the lower resistances, but the lab power supply gave the same results.

Any help with this would be greatly appreciated.

Here are the components I'm using:

M1: https://www.mouser.com/datasheet/2/196/Infineon-I80P03P4L_04-DS-v01_01-en-1225645.pdf

R2: http://ww1.microchip.com/downloads/en/DeviceDoc/22060b.pdf

I'm using generic 2n2222 npns for Q1 and Q2.


texts: Transformer vs. motor soft start devices

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I like to drive an older, large CNC machine on a smaller power outlet. The machine is made to work by one 32A three phase outlet, but it is servo-driven and only demands a fraction of the maximum current if driven softly or with light loads.

However, the large non-switching power supply will trigger the circuit breakers on a 16A circuit.

So I like to add an soft start device. There are special devices meant for "transformers", but they are hard to get. What is the difference to an ordinary soft-start for motors? Would such a device allow to start the transformer without triggering the breakers too?


texts:
I am experimenting with different TTL components and am having a lot of trouble with the 74160 decade counter. I don't know if it's my inexperience or if I'm dealing with a malfunctioning IC, but the IC isn't doing what it's supposed to, and it heats up pretty darn fast (I always check for heating once I power up)

After some testing, I noted that all I have to do is connect the GND to ground and the +5V pin to 5V and it starts heating up fast. If I add a resistor connecting to ground, it doesn't heat up, but it heats up once I connect the remaining pins (as it stands, pins 7 and 8 are grounded, 9 and 16 are in +5). As soon as I power it up, all the outpins turn HIGH.

So here is what I'm wondering:

Do I ever need a resistor once a TTL datasheet tells me to connect such and such pins to ground or to +5V or can I connect them directly?
Can I conclude that my 74160 is short-circuited/malfunctioning?
Is there anything else I might be doing wrong?


texts: Is it possible to replace this radar gun handle wiring with a battery?

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I have a radar gun and the detachable handle needs to be directly plugged into a car cigarette outlet in order to work. This is quite troublesome as I always need an outlet and a cigarette socket to wall outlet converter for it to work. Today I measured some voltages and took apart the handle.

The voltage I measured at the end of the handle was 7.6 Volts (where the red arrow is). The input to the handle is a standard 12 VDC. Looking at the manual for the radar gun, it appears peak operating needs are 7.6 Volts and 0.66 amps. I am wondering if anyone would know what is going on within the handle itself. If I took out everything, could I in theory replace all the wiring with a battery and solder it onto where the red arrow points to?
For reference, the entire radar gun and handle looks like:


texts: What is the best tool to hold small printed circuit board?

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To solder a small PCB I need something that can hold it very tightly, so I can touch it and it won't move.

I tried a lot of tools. First I used this third hand with magnifying glass below. But it can damage the board and is not so good for my things.

Then I tried this PCB cell phone circuit board repair holder kit". Didn't work either.

But the best tool I tried was this PCB holder (sorry, but I can't find an equivalent product in a website writen in English).

This last one is ok, but it's tricky for a very small PCB. Besides, it is a little weak. It moves if I make a little more pressure on it.

Another tool I tried to use was this small bench vise, but it is not so good to hold a PCB.

Any more ideas? Is there any specific tool to hold a small PCB?


texts: In an open circuit, are capacitors still in "series"

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In the picture below, there are two capacitors right next to each other in an open circuit (ie the wire with V2 written above it does not go to ground). Assume that each capacitor had been previously 'charged' up so that they have different amounts of charge on them (each was charged in a different circuit). Then, in the scenario below, would the capacitors be "in series"? I'm asking because I made the assumption that the charge on both capacitors would be the same (I thought they were in series) and I got the problem wrong (the solution did not make the assumption that the charges would be the same).

So, essentially, what I'm asking is when can we assume two capacitors are in series and why are they not in series in the image below? Also bonus question if anyone can answer: the solution said that no charge would leave either of the capacitors. Why is this so? If one capacitor has an excess of electrons (like the left plate of C2) why don't they migrate to a capacitor with a deficiency of electrons (like the right plate of C1).


texts: Why doe the sequence 16*[10,6,5,9] work for a bipolar stepper motor?

texts:
I programmed a bipolar stepper motor (Step Angle: 1.8 degrees) connected to the computer via a velleman K8055 usb board and coding in MATLAB. I thought the sequence for full step drive was [12, 6, 3, 9], but it didn't work so I tired the sequence [10,6,5,9] which I found when I googled and it worked.

The site didn't give an explanation it jut gave me the sequence.


texts: Wall supply transition to a 2nd wall supply

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A device has various supply rails, but they are all derived from one 9V wall supply via switcher and linears.  What kind of issues can occur if the device is unplugged from one wall supply and then plugged in another, within seconds?

Are the grounds of the two equivalent or can weird reverse biasing happen momentarily; especially if the ground or power terminal of the 2nd supply doesn't connect simultaneously?

Is there some terminology that I am missing that could help in searches?


texts: Questions regarding using an HDMI cable to transmit SPI, I2C, and UART serial data?

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I'm currently working on a design in which I need to transmit serial data over 3 different serial channels. I won't be transmitting data far (1" - 1') but I didn't want to use plain wires. Instead, I thought it may be useful to implement the standard HDMI connector and cable to transmit this data. However, I have a few questions.

1) Are HDMI cables designed for only transmitting data on specific conductors? It appears that some of conductors are 'paired'. I assume I would just need to be cautious on what conductors I place the signals? My serial data will be transmitted much slower than most audio/video data streaming that HDMI is typically used for.

2) I'm going for a compact design, I've thus considered using micro HDMI for the small form factor. Besides the form factor, are there any other differences between micro and standard HDMI connectors/cables?

3) Where are we at with regard to the life time of HDMI cables? I'm trying to create a device that will last a long time. Is HDMI/Mini HDMI/Micro HDMI on there way out any time soon? I know they've been around for close to a decade now, are there any other rising standards that I should be considering?

Thanks!


texts:
I'm quite beginner in electronics.

So, to begin with, I wanted to make a simple (?) ultrasonic rangefinder, based on microcontroller. So I had a few questions for experienced in electronics:

What would be the best environment for development - breadboard, or something else ?
What would be best to use: sender and receiver as one unit (example: BPU-1640TOAH12) or a separate units for sending and receiving: Velleman MA40A5S (send) and MA40A5R (receive). If it matters, I would like to measure a distance up to 5 meters.
What is a typical power supply source for such a circuitry ? At least in development. Batteries ? Or something else ? What parameter (voltage, current) would affect the output signal strength ? Do I need to have some advanced op-amp chains (or some other amplification elements) ?
What microcontroller should I be using ? Should be very cheap and simple(= without extra unutilized features). What would you recommend ?
What about using "Proteus" ? Should I trust this program ? Is it any good ?

P.S I'm NOT interested in Arduino.


texts: Can I cut up a proprietary barrel connector cord and make a USB power cord with it?

texts:
I have a Yaesu VX-8DR radio, and its power input is a barrel connector. In the age of smartphones, where basically every single device I have uses a USB cable to charge at up to 2.4 amps, I'd like to make a USB cable to power this device as well. I have a small case I pack around with a charger and assortment of USB cables, and I'd like to just add one more USB-to-power-barrel cable to it, rather than two additional discreet proprietary car charger and wall charger units.

(Or buy one; I don't know the barrel connector size, though, and I don't have calipers, and I don't see it listed anywhere in the manual. Although this answer to another question I found here seems to indicate exactly what connector I may have, if Yaesu followed this standard. The plug does have the yellow insulating ring as mentioned in that answer.)

The Yaesu car charger output current is 2A, and the included wall charger output current is 1A, both at 5V like all my USB devices. This means I should be able to use my existing USB car charger that outputs 5V/2A and my existing USB charging hub at home, right?

To clarify, I want a full-size USB connector on the end where there is currently an integrated wall-wart or an integrated car power plug. The barrel connector will stay on the radio end of the cable, I just need to feed it from USB instead of feeding it from an integrated plug.

Can I literally just chop off the integrated cord that runs out of the car charger and solder a full-size USB connector to the end and call it good?

Secondarily, the radio treats any connection on this power port as "attached external DC power", and increases the output wattage on the 1.25m band from 1.5W to 5W until the external power is removed. If I connect this new USB connector to a battery (such as one used to recharge a dying cell phone) is there any possible problem with this increased output wattage connected to a battery instead of to an actual continuous DC power source?


texts: KSZ8863MLL issue - suggestions on resolving

texts:
I have a NXP K64 cpu connected to a KSZ8863MLL (two port Ethernet switch) operating in MII mode.

I built 10 boards -- 9 work.

The board that does not work properly behaves as follows (testing using JTAG)

When K64 is in reset - KSZ8863MLL operates (network leds and activity leds active).

In the K64's EMAC code setup, the K64 pins are mapped into MII mode.

When K64 pin MMI0_TXD2 is set to MMI mode - the pin goes from a floating input (3.3v on scope) to GND as the pin becomes an output.

At the conclusion of executing THAT pin's related instruction - all LEDS on the KSZ8863MLL go out and the device becomes inactive.

Programming all other MMI related pins on the K64 have expected results.

I have looked at the board under an inspection microscope and found no trace/solder issues.

I have scoped adjacent PCB traces to see if an internal PCB layer may have shorted traces (PCB is 4 layer) -- no change to adjacent traces found when pin goes from input to output.

I have placed a break point after the instruction to make sure other code was not executing and to isolate the KSZ8863MLL behavior to just that single instruction.

I've narrowed it to that single pin - going from input (pin at 3.3v) to output (pin a GND) that causes the KSZ8863MLL to stop operating.

I'm lost as were to look/proceed further.  As stated earlier -- 9 other boards work perfectly which suggest the issue is related to parts/assembly of this specific board.

The KSZ8863MLL appears to be OK since it shows activity as long as the K644 has not set that pin's mode to MMI.

The 3 other related TX pins (TX0, TX1, TX3) all go from 3.3v to GND when their mode is switched to MMI.

Any insight or suggestions?


texts: Failure of LEDs in the wet -- what's going on at the semiconductor level?

texts:
Recently I've come across two very different LEDs that have failed due to a soaking, but with interesting and almost identical failure behaviour.  I'd like  to understand what's going on inside.

Once dried both emit, but not as expected.  At a reasonably high current (i.e. close to their maximum rating) they give a steady light which by eye is indistiguishable from normal behaviour.  At lower drive currents the output is less than normal and flickers. The (apparent) Vf, fluctuates. At still lower currents, but enough to normal give clear emission, there's nothing.

The first is a 365 nm 1.2 W from LED Engin used in an aqueous photocatalysis by undergrads who presumably got it wet.  This is run off a bench supply so I can test it more thoroughly. The second is a red 5050 single emitter in a rear bike light that got soaked in a storm.  Failure is only apparent when on standlight mode (running with a lower drive current than if moving, powered by a 1F 5.5V capacitor that I initially blamed). A thorough  drying made no visible difference (in fact dried, rinsed in DI water, dried, baked in a 100°C oven for an hour, tested at every stage).

This is mainly out of curiosity; I've got some background in semiconductor failure but nothing like this.  The failure mode seems interesting in the way it manifests at low current by higher currents seem fine.


texts:
I found this tool in a toolkit which I had lying around.
I am not sure what this is as I didn't purchase this kit.
The kit, in addition, had a ratchet screwdriver, bits and some tweezers and a precision pickup claw tool.


texts:
I have a project where I want to interface with a keyboard matrix / scanner (this is a PCB from a consumer electronics device). There's already an implementation that uses some analog muxes for this, but I'd like to change this to an MT8809 8x8 crosspoint switch: https://www.microsemi.com/product-directory/analog-cross-point-switches/4916-mt8809
That is, the MT8809 will be used to connect/disconnect the rows and columns of the matrix scanner to simulate keypresses.
The MT8809 runs at 4.5-12v, so I'd connect it to a 5v rail, but the device I'm interfacing to runs at about 3v. Are there any concerns here? Do I need to clip the voltage?


texts: How to control a 12V solenoid valve with a mosfet?

texts:
I'm trying to control a 12V DC solenoid valve through a MOSFET (BS170), which receives its control signal (5V) from an Arduino microcontroller.
This is the basic schematic:

When I test the MOSFET, putting a LED with a 1.5k ohm resistor as Load (see picture), it works fine and I can control the 12V current with the 5V signal, without problem.

But then I connect my solenoid valve instead of the LED. It works for a few seconds, then it stops working and the MOSFET ends up permanently conducting current, regardless the state of the 5V control pin.

The MOSFET is permanently damaged, because when I connect the LED again, it doesn't work anymore.

Too much current? But when I add a resistor before the valve, it doesn't operate anymore...
Maybe I need a heavier MOSFET/transistor?


texts:
I have a clock with a 50% duty cycle, driving a 3-bit ripple counter.
When Q2 is high, external lines such as address are stable. I want to generate a short read pulse between 50% and 75% of the Q2 signal to latch in data from external RAM / ROM.
Below is what I am using in LogiSim. But if I remember back to my digital electronics days (1980!), I can get a glitch between when the counter (Q2, Q1, and Q0) changes state, which might trigger a spurious RdPulse.
Is there a race hazard (e.g., when the counter changes from 111 to 000)? And if so, how can I avoid it?


texts: Current source - Achieving a defined settling time with variable load resistance

texts:
I'm trying to build a voltage-controlled current source which is supposed to work with a wide range of load resistances. Currently the plan is to use an NPN transisitor as voltage follower to do the heavy lifting, and control the current with an op amp:

simulate this circuit – Schematic created using CircuitLab

The load resistance RLoad does not change quickly (< 1 Hz), but can vary over a huge range (10 Ohm - 10k Ohm).

Since Q1 is a voltage follower, the op amp output voltage basically controls the high voltage on the load. Since the highest current I need is 50mA, the low voltage on the load is at most ~1.5V.

Now, this feedback loop for the op amp has some delay, which can cause the circuit to oscillate. The capacitor C1 is supposed to prevent this by adding lowpass behaviour.

This all works pretty well, but there is a catch: When I change the desired current by changing V_in, I want the controller to closely approach the new current in 1ms or less. However, the speed at which C1 is charged / discharged depends on RLoad with this circuit, so a large RLoad causes the output to settle very slowly.

This is because C1 is charged over R2, with a current that only depends on the difference between the actual shunt current and the desired shunt current. With a high RLoad, the op amp needs to output a higher voltage, so it needs to charge C1 to a higher voltage, which takes more time.

How can I modify this circuit so that the settling time becomes independend of the load resistance?


texts: Buffer amplifier used in medical implant hearing aids

texts:
I am new here, so if I am posting in the wrong area, please let me know.

Recently at the university I've had a guest lecturer, that works at Cochlear developing medical implant for the hearing impaired. This guest lecturer mentioned and drew an example diagram of a buffer amplifier with a 10V rail to ground supply with an input voltage between 1-10V, which would mean an ideal output of 1-10V since its a buffer. He also mentioned about additional voltages added with Vin such that if Vin = 1V(min), an additional 0.5V would be added to it hence Vin = 1.5v... or Vin of 10V(max) = 10V + 0.5V = 10.5V ranging between 1.5V-10.5V!? Unfortunately I was unable to ask after the lecture and he was very brief with it. But this has been bugging me, since I don't have any idea, why this would be useful, to have additional voltage at the input in that kind of implementation?


texts:
I need to draw a circuit taking a number on 4 bits that will return 1 only if that number is divisible by 3.

My initial steps were to draw a truth table from which I got a Boolean expression that cannot be simplified.
I then drawn a Karnaugh Map, same result.
It seems as though such Boolean expression would be really annoying to draw as is, I'm pretty sure they're an easier way.

My second thought was to use 4 "1 bit adder" in series, outputting the alternating sums; the last sum must be 0 in order to be divisible by 3.  How would that work exactly? Would I need to carry the result of the addition even though it is pretty irrelevant to the whole circuit?


texts: TCP/IP stack library for ST microcontroller

texts:
I'm looking for a free function library, that implements TCP/IP stack for STM32F103CBT7 (Cortex M3) microcontroller. The datasheet of this controller is following:
http://www.farnell.com/datasheets/1730126.pdf

I have been looking for this library for a long time. I found some librarys, but they are not free. Could someone recommend me a free one? The hardware won't be used for commercial purposes.


texts: How to use the full 10-bit PWM resolution (PIC18F2xk22)?

texts:
Hi I am trying to use the full 10-bit PWM resolution for my project, and there is a problem as the duty cycle of the PWM will not set to zero when I rotate the POT to the zero position, here is my code in brief..
  CCPR5L= ADRESH;
  CCP5CONbits.DC5B1=(ADRESL>>7) & 1;
  CCP5CONbits.DC5B0=(ADRESL>>6) & 1;

I have basically Left adjusted the ADC so that the most significant bits are stored in ADRESH and the 2-LSB are stored in ADRESL. I have tried to copy the 2 LSB bits of ADRESL in to CCP5CON bits (as stated in the datasheet), however it will not set to 0, but if remove :
  CCP5CONbits.DC5B1=(ADRESL>>7) & 1;
  CCP5CONbits.DC5B0=(ADRESL>>6) & 1;

and set the bits in
CCP5CONbits.DC5B=0b00;

to zero PWM works just fine and 0 duty cycle is achieved, but only with 8 bit resolution. Any Ideas on how I could solve this problem ??


texts: Do induction motor stators and rotors have star or delta winding configurations?

texts: For induction motors, which type of connection, star or delta, is used in the stator winding and the rotor winding and why?


texts: Finding timestamps of CAN messages received by a microcontroller

texts:
The microcontroller kit (STM32F4 discovery kit) which I am using has CAN and USB support. I want to program my microcontroller so that each time when a CAN message is received, it is transmitted via USB to the host PC. I also need to see the time at which each CAN message was received. In the host PC I can see this information.

How do I find the time information about the CAN message received, that is, at what time was each CAN message received?

I already have a method which I will explain here. I need your suggestion regarding my idea or you may suggest a new method.

My method: Run a timer inside the microcontroller. Each time a CAN message is received, the value present in timer is stored and the timer is reset. The stored timer value along with the CAN message information is transfered via USB to the host machine.

Here each timer increment might be equivalent to 1 millisecond or 1 microsecond depending on the timer configuration. The microcontroller will be always sending the time difference between two CAN messages.

I am also planning to use another counter which would increment for each timer overflow. Sometimes a CAN message might only arrive after two seconds (or even some other time). In that case the timer can overflow. Each time when a timer has finished, the counter will be incremented. This happens until next CAN message arrives. This counter value will be also transmitted to the host PC.

How is my above method? Is there any better idea?


texts:
If i have a generator with a reactive component and resistive component are these in series of parallel?

and

When considering the impedance of a transmission line, should the impedance from the generator  be added in series?

Best regards
Danny J


texts: When I can't short CS to ground using only one SPI device?

texts:
Last time I was writing an easy program for some old processor to interface with MCP3004 (Microchip's ADC with SPI interface). Processor had no hardware SPI implementation so I had to write it on my own.

To my surprise program didn't work until I changed the code to toggle CS down-up-down with some delay each time I am communicating with ADC.
Always before I was sure that ChipSelect can and even should (to reduce amount of used pins) be physically shorted to ground when I use only one device.

Is there any explanation why that time it didn't worked: when I can't short CS to the ground when I am using only one SPI device?


texts: Is there any color sensor that reads R,G,B and Clear channel values in parallel?

texts:
Currently, I'm using a color sensor TCS3200 it has 8x8 photodiode array, of which 16 are RED filtered, 16 are Green filtered,16 are Blue and 16 are clear. I can read one color channel at a time i.e. if I'm reading RED I cannot read other three channel i.e. Green, Blue, and Clear of the above-given sensor. The sensor I'm looking for is that reads all 4 channels in parallel. I looked at some CMOS camera sensor modules like OV7670 but it does not run faster than 30fps and I don't need that kind of resolution either.
For my application, I need the sensor to be able to read values at a minimum rate of 120 fps.
So I wanna know is there any sensor that achieves parallel RGBC channel reading.
Note- My application is color sensing, not imaging


texts: Controlling a 4.2V LED (LCD backlight) with a microcontroller

texts:
I have a PQC1602K-SYL alphanumeric LCD display with a backlight LED. I would like to drive the LED using a microcontroller pin. How can I achieve that?

What I have tried

According to the data sheet, the LED requires 4.2 V and 100 mA.

My circuit works on 5 V, therefore I need to drop the voltage to 4.2 V. Using Ohm's law I have calculated that I need a 8 Ohm resistor, assuming 100 mA go through the LED. If I connect the LED directly to the supply, like in the following circuit, the LED turns on at full brightness. I measured the current that goes through the LED and I get about 85 mA. I am not sure why it is not closer to the specified 100 mA, though.

simulate this circuit – Schematic created using CircuitLab

I can't substitute the power supply with the microcontroller's output pin because the 100 mA (or 85 mA ??) are more than the pin can supply, therefore I need some kind of buffer. I believe that a common solution is to use a transistor using a connection simmilar to the circuit below. However, my knowledge of transistors is very limited and rusty. I have tried to calculate the values of the resistors using Kirchoff's laws but I could not reach any meaningful solution. I then tried experimentally with some NPN transistor I had lying around and I managed to reach the desired voltage by completely removing the resistors, but I only get 30 mA through.

simulate this circuit

Please help me learn how to find the solution to this problem.


texts: Swapping positive and negative traces of an LVDS oscillator

texts: Can I swap the positive and negative traces of an LVDS oscillator (Si series of silicon labs) when connecting to clock pins of an FPGA? If no, what about adding series capacitors and using AC coupling technique?


texts: Pull-up resistor power rating on signal wire in automotive?

texts:
I have a 1k pull-up resistor on an input line of a microcontroller on an automotive part.

The signal is coming from another product in the vehicle which is meant to deliver 12V.  In this case one might think that the current will be 12mA through the pull-up and hence the power will 144mW so maybe a power rating of 250mW would be appropriate for the resistor.

However, in automotive, there can be very large transients and if the signal becomes noisy or the other product which communicates with our device has a defective or badly designed filter (over which I have not control), it's possible there could be some large transients on the signal line.

  Independent studies by the Society of Automotive Engineers (SAE) have
  shown that voltage spikes from 25V to 125V can easily be generated
   [ref], and they may last anywhere from 40ms to 400ms. The internal
  resistance of an alternator is mainly a function of the alternator
  rotational speed and excitation current. This resistance is typically
  between 0.5Ω and 4Ω (Figure 2).

Does anyone know if the power rating of pull-up resistors in automotive systems are typically rated higher than normal?


texts: Testing cellphone speakers out of circuit

texts: What is the best low cost way to test a cellphone speaker out of circuit at the test bench level?


texts: BQ29700: Problem with the battery protection

texts:
this is my first post here!

I have a problem with a custom board I made.

The problem is when I plug the battery nothing happens, no voltage flow, but if I touch the VBAT- with GND of my PCB for a instant, the voltage is OK all the time, the current flow and the battery works properly.

3.7 V battery Li-Ion 1 cell

Any idea are welcome!


texts: Audio volume levelling / AGC for spectrum analyser

texts:
I'm busy building a preamp, and want to include an LED-matrix spectrum analyser on the front panel (for aesthetics, not accuracy!)
I've set up a circuit that uses a couple of MSGEQ7 chips to analyse both channels of an input audio signal, feeding an Arduino with amplitude values for 7 frequency bands in near-realtime. This is then being number crunched, constrained and used to drive the LEDs in my matrix, and the results are awesome. So far so good.
However, the effectiveness of the spectrum display varies wildly depending on the input volume level, and even from song to song. If the input volume is too low there's barely any activity on the LEDS, and if the volume is too high then they're all on the time. There's a volume "sweet spot" where the display is ideal - the bands nicely dancing to the music - and as such I want to build a VCA / AGC / audio leveller circuit to normalise the incoming audio to a (somewhat) constant volume to drive the spectrum analyser, ensuring sexy visuals regardless of input volume or how the song was recorded.
I've got both the THAT 2162 IC as well as a couple of SA575 compandor ICs, both of which I believe can do the job.
However, in both cases I can't get my head around how to configure the chips to suit my needs:
THAT 2162:

...I'm not sure how to determine the values of the EC- terminals (pins 4 and 13), which I assume set the level at which the signal will be compressed/expanded.
SA575:

...likewise for the SA575, I assume the VREF terminal (pin 8) is also used to determine the target level, but again not sure how to calculate its value.
Questions:

In each case, how would I configure these ICs to accept a line-level audio input, and consistently normalise them to get an output signal that's (approximately) always the same volume?
Am I barking up the wrong tree, and if so is there a better way to do what I need?


texts: where can I find the symbol of BNC in LTspice

texts: I am working on LTspice and I need to put a BNC at the input of my amplifier. where can I find this symbol?


texts: Constant-current driving with LED Driver and Boost DC/DC converter

texts:
Novice here, sorry if I'm missing something obvious.

I'm trying to drive 4 strips of 6 low-power RGB LEDs each (APF3236LSEEZGKQBKC) on a 3.3V battery.
I have a 12-channel LED Driver (TLC6C5912) which seem perfect for the job.

However, voltage is an issue, as each green or blue channel could need up to about 20V depending on the brightness I settle for.
A DC/DC boost converter seems to be the way to go to get 20V bursts out of my little battery, but from what I know, I should drive LEDs by constant current, not constant voltage, in order to account for brightness variations and possible damage due to temperature rises.
I was thinking something like the TPS61096A.

Should I use something else than a DC/DC boost converter? Or add something to it to control the current?


texts:
This is my first question on this forum. I recently bought a used guitar amplifier and have the schematic. It's been almost 30 years since I worked in electronics but I thought maybe I could handle the circuit analysis of the power supply.
This amp runs off a typical 120Vac, the secondary voltage of the power transformer is 132Vac and the schematic shows the rectified DC voltage as 319Vdc. I've checked the test points shown on the schematic and the measured voltages are fairly close. My question is how does this rectifier achieve the 319 Vdc?


texts:
something about mesh analysis confuses me and I can't find an explainaton anywhere, as you can see on this picture (it's in French, but the schema and formulas should be enough to understand)

They bascially explain how mesh analysis works, and that's fine and all, I understand the formulas but then I get this exercise :

And as you can see they just put I2 = -2A. Why do we not care about the 12 and 3 resistances ? The exercise is basically the same as the image shown above and in that one we  take both R2 and R3 into account.

Is it because this time we have a current source ? Or because we are on the "edge" on the circuit ?

Thanks for reading and thanks in advance to those who will answer


texts:
I just started using the STM32 F401VC Discovery Evaluation board and I'm trying to get the maximum GPIO toggling frequency without assambler. So my tought process is following:

The code I was planning to use is:

#include "stm32f4xx_gpio.h"
#include "stm32f4xx_rcc.h"
#include "stm32f4xx.h"
#include "stm32f4xx_spi.h"

void initializeGreenLed(void){
    GPIO_InitTypeDef GPIO_InitStructure;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOD,&GPIO_InitStructure);
}

int main(void)
{
    //RCC_CFGR;
    initializeGreenLed();
    //initialiseSysTick();
    GPIO_SetBits(GPIOD,GPIO_Pin_12);
    while(1)
    {
        GPIO_ToggleBits(GPIOD,GPIO_Pin_12);
    }
}

The max pin toggle frequency I get is around 230 KHz. Since the MCU can be run at 84 MHz, I have a feeling, that it's possible to increase the max toggle frequency beyond 230 KHz.

So I tought that I need to change/modify the clock source for RCC_AHB1Periph_GPIOD in RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);. For that I used the STM32 F4 reference manual.  So my plan was to use PLLCLK as SYSCLK. The PLLCLK would be sourced from 8MHz HSE.

Browsing through YouTube, found a nice example:

#include "stm32f4xx_gpio.h"
#include "stm32f4xx_rcc.h"
#include "stm32f4xx.h"
#include "stm32f4xx_flash.h"

void initializeGreenLed(void){
    GPIO_InitTypeDef GPIO_InitStructure;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOD,&GPIO_InitStructure);
}

int main() {

//---------------------------down is clc stuff---------------------------

    RCC_DeInit();

    ErrorStatus Errsts;
    RCC_HSEConfig(RCC_HSE_ON);
    Errsts = RCC_WaitForHSEStartUp();

    if (Errsts == SUCCESS) {
        //external clc is ok
        RCC_PLLConfig(RCC_PLLSource_HSI, 8, 336, 2, 7);
        RCC_PLLCmd(ENABLE);
        RCC_GetFlagStatus(RCC_FLAG_PLLRDY == RESET);

        FLASH_SetLatency(FLASH_Latency_5);

        RCC_HCLKConfig(RCC_SYSCLK_Div1);
        RCC_PCLK1Config(RCC_HCLK_Div4);
        RCC_PCLK2Config(RCC_HCLK_Div2);

        RCC_SYSCLKConfig(RCC_SYSCLKSource_HSE);

        initializeGreenLed();
        while(1){
            GPIO_SetBits(GPIOD,GPIO_Pin_12);
                }

        }
    else {
        //External clc no ready

        while(1);
    }
}

But it doesn't work, as in it just stays in one state.

So I have two questions:

Why isn't my code working?
If my abovementioned strategy is incorrect, how to increase the toggle frequency beyond 230 KHz?


texts: Differences between TVS diode and Zener diodes, in diagrams and in practice?

texts:
I have been looking at circuit protection using TVS and Zener diodes.

I have seen the following symbols used to represent TVS diodes in circuit diagrams:

simulate this circuit – Schematic created using CircuitLab

I guess the first question is whether there is a meaningful difference between TVS and Zener diodes, and the answer seems to be, "Their characteristics are similar, but their design and test specs, and intended applications, are different:  Zeners are for specific and potentially continuous voltage regulation.  TVS diodes are less precise about voltage and designed rather to shunt (and survive) large power transients."

My impression so far is that of the symbols above:

Should be assumed to refer to a Zener diode (unless notes indicate otherwise).
Unambiguously indicates a TVS diode.
Unambiguously indicates a TVS diode.
Probably refers to a pair of Zener diodes, but could refer to a single TVS diode.

Are these reasonable assumptions?

I imagine that the only time one would consistently run into trouble is when using a TVS diode instead of a pair of Zener diodes.  E.g., using a TVS diode, with its imprecise breakdown voltage, when the circuit calls for a "waveform clipper" would produce terrible results.  On the other hand, using a Zener when a TVS was intended one would likely either never notice the difference if large power transients aren't part of routine operation, or else one would probably notice the difference quite quickly as the Zener was fried?

Or is the correct answer to this ambiguity simply, "Yes, they're ambiguous.  And until you're sure which diode to use you're not ready to build the circuit."


texts:
I'm really confused about how JFETs work. JFETS are usually significantly higher doped donor xor acceptor atoms.
My professor mentioned that MOSFETs usually have an oxide in between the the metal and semiconductor. One of the benefits of this oxide is that it prevents leakage (which I think it minority-carrier current correct?). Can someone explain why this is?
He then went on to say that suffers from leakage current. However if the JFET is so dominantly doped with one type(n or p), then this doesn't really matter, right? Can someone explain why I'm wrong please?
Any pointer to reference material is greatly appreciated as well!


texts: HDMI Cable interfering with mobile phone network

texts:
Just had a "spectrum engineering officer" from OFCOM (the UK's communications regulator) visit our office investigating alleged interference from our building with a local cell phone tower. After waving an aerial attached to what looked like a portable spectrum analyser around he decided that the HDMI cable feeding a set of four TVs was causing the problem.

This seems extremely unlikely to everyone in our office and we are wondering of their is any validity in his claim. We are a ground floor office in a modern concrete building and the phone tower is on the the opposite side of the street on the top of a multi-story car park (about 4 stories high).

Is it possible for a leaky HDMI to cause such interference?

(He did assure us that we haven't broken any regulations and that no action would be taken.)


texts: Altium Double Counting Unit Quantities in BOM?

texts:
I've got a schematic that has been through several revisions, and I noticed when generating my BOM that the most recent two revisions are now generating an error in Reports > Bill of Materials tool.  For some reason some components are being double counted.  Like a resistor that is only used once, is showing as a quantity of 2 in the generated BOM?

Has anyone ever run into this with Altium? The schematic two revisions ago, correctly counts the quantities but I evidently did something that upset Altium...


texts: Measuring current in independient circuits

texts:
I'm doing a project to monitor and control 5 separate air conditioner units in my house.

The AC Units run in 240V power (two 120V phases), each unit has its own breaker in the box.

I'm using five current transformers, as outlined here: http://openenergymonitor.org/emon/buildingblocks/ct-sensors-interface to detect the current flowing to the AC (<0.01 = off, between 0.03 and 0.8A just the fan, and 2A and up means full compressor running).

Everything mostly work, the only issue I have is that when I turn on a unit I get a current spike in another unit for a while, and that throw off my logs. I can confirm this reading with my clamp shell ammeter

I think this is because the cables are inducing current on each other (they all go through the same conduit).

Is there anything that I can do on the electrical side to get rid of this effect?


texts: A simple circuit to turn on door LED when someone visit me

texts:
I want a simple circuit do an alarm light that tell me someone visited me.
When someone visits me and in the case no one answer the door, I want to know that.

So I want a press button switch outside the door that will turn on a LED inside the house and will not turn off until I reset it inside the house.
How simple that can be done?

Best to make use of my existing rechargeable USB battery that is used for phones.


texts: Can you make a ripple counter count in Gray Code?

texts:
The Task:
I was given the task of designing a decade counter using J-K Flip-Flops. What I immediately thought of was whether I should make it Synchronous or Ripple. And here is where I started getting confused.
What I know:
Now, the main advantage (that I am aware of) of synchronous over ripple counters is that they are more reliable, as in they do not have propagation delays, which can make an output go from
0111 (7) --> 1111 (15) --> 1011 (11) --> 1001 (9) --> 1000 (8)    (transiently) otherwise, they are more complex to design and generally require more circuitry.
My Question:
So, can a ripple counter count in Gray Code? And would it solve this propagation delay problem? I thought this would make any propagation delay irrelevant, because, for example, a number would change from 0100 (7) to 1100 (8) without going through transient states no matter what delays are present in the circuit. This would, in turn, make the asynchronous counter the better choice.
I must also say that the clock's frequency is really low (1Hz), Will any of this matter in this case?


texts: Calculate charge time of a capacitor through a current limiting power supply?

texts: Is there a formula or a way to calculate Charge time of a capacitor given that it is charged by a current limiting power supply. This would lengthen the charge time but is there a way to calculate this due to the power supply limitations. Let's say that we are charging a 1uF Capacitor to 5,000VDC through 20kOhms of resistance in series.


texts: Current through heating element lower than resistance suggests

texts:
The fuser lamp (the heating element) in my laser printer broke from one of the ends. I measured the resistance of the, almost full length, wire which was 6 ohms. I tried to fix it by connecting the wire to the printer but the wire kept breaking after a couple seconds at the connection (it was exposed to air + mechanical stresses caused by my tinkering).

So, I decided to make my own heating element from nichrome, 7 ohms to be safe. Now comes the strange part: this 7 ohm element causes the fuse of the printer to burn almost instantly. Confused, I measured the current through and the voltage over the original broken element and they were 5A and 230V, I assume 50Hz AC, even though 6 ohms and 230V should give 40A (which, I know, is way too high with the 6.3A fuse).

I came up with two explanations:
1) I didn't measure the reactance of the original element (it's a coil).
2) The original element's resistance goes up a lot when it heats up (I don't know the material).
But neither of them seems to be significant enough to raise the impedance high enough.

So, my question is: What could cause the low current?


texts: RS485 Common Ground: Common Voltage or Common Wire or Both?

texts:
RS485 connection needs a common ground, but I am very fuzzy about how that works over longer distances and more complex systems.

When the transmitter and receiver are about 1000m apart, there will be a voltage drop so the receiver won't have the same voltage on the ground as the transmitter, will it?
Say if I power them separately and ensure a 5v ground on both ends, will that work?
Or if I run a higher voltage line and ground wire and then step it down to 5v for the receiver and transmitter, technically that will still be the common ground, or will it?
Finally, if there are a bunch of devices connected to that common ground, won't that interfere with the signal? If yes then should I have a separate dedicated ground just for the RS485 connection and another ground for everything else?


texts: Can I change the input voltage for this temperature-controlled fan circuit:?

texts:
Possible Duplicate:
  Can this temperature-controlled fan circuit be modified for different input voltage?

For the above temperature-controlled fan control circuit which is originally designed for 110V supply, is it possible to operate on 220V?

Also, since the main function of slowing the fan when it's cool and speeding it up when it's hot is done by NTC, why is PTC required? Also what's the purpose of cap and inductor?


texts:
Many IC's I've seen suggest decoupling capacitors across Vdd to Vss - this is sensible.

However some IC's for example the dsPIC33FJ128GP802 has THREE Vss pins and only two Vdd pins (AVdd and Vdd.) So would I put a decoupling capacitor on each Vdd pin, or from each Vdd pin to each Vss pin?


texts:
I want to find junk yards to get components, transformers etc.

When I search google, all I see is "we buy junk"

How can I find where the junk is like broken microwaves, tv's etc?

I live near Denver, CO


texts: How to find the output impedance of a two BJT small signal circuit?

texts:
Like for instance, the picture above. How to find the output impedance?

My thought was like draw the small signal circuit of them, then do the equivalent. But I am not sure if I need to short the current source of Q2 or not. I know that for Q1, I need to short the current source, cause Vbe for Q1 is zero. What should I do? Thank you.


texts:
I would like to create a circuit that takes in two pulse trains that exchanges output lines depending on which pulse comes first. Currently I am using an ON 7WB383 and switching the signal manually by setting the EX depending on whether A or B signal comes first. So if A comes first A->C and B->D. If B comes first then A->D and B->C. Is there easy way to have this done automatically or an alternate IC that will perform this function internally?

The pulses have a frequency of once per second and a width of about 100 microseconds.

Im using another IC after this to measure the time difference between two pulses but to do this the pulse coming out of C always has to be before D.


texts: Will this IGBT switch operate correctly?

texts:
I am working to design a static AC switch using an IGBT module. The idea is that the switch will protect an inductive load from an adverse voltage condition (such as excessive under or over voltage) and disconnect the load from the mains. For now, it will need to switch single-phase 120VAC, and the load will be 1kW or smaller.

The IGBT module I have selected is an Infineon FF300R12KT3_E module (https://www.infineon.com/cms/en/product/power/igbt/igbt-modules/ff300r12kt3_e/), which features dual common-emitter IGBTs. My schematic shows a standard optocoupler, but I am considering using an Infineon 1EDC60H12AHXUMA1 IGBT gate driver or similar (https://www.infineon.com/cms/en/product/power/gate-driver-ics/1edc60h12ah/). This will be powered from an isolated 20VDC power supply, and controlled via microcontroller. I have the IGBT modules but not the gate driver yet.

Does this design seem robust enough for my needs? The circuit is based off an older design design by International Rectifier (Now Infineon). I am not sure the resistor between the gates and emitter is necessary. Actually, I'm wondering if anything else could be done that might protect the gate regions against turn off oscillations. Any feedback would be much appreciated.


texts: How to select the best opamp for a constant current MOSFET driver

texts:
I'm trying to create a constant current LED driver. I have found and read information about the miller effect and came up with the schematic below.

What are the most important parameters for choosing the Opamp?
Is this the Slew Rate, Gain Bandwidth Product, or any of the other specifications?

I was looking at an Opamp and power it with ±15 Volt since the MOSFET has a maximum VGS of ±20 Volt.

UPDATE: I was thinking of a opamp like this one BA4580YFVM-MGTR

Frequency: 1-100 Hz
Pulse duration: 100-300 us
If: 1A during pulse

simulate this circuit – Schematic created using CircuitLab


texts: How to switch a 12V DC (3A) Motor with a 3.3V signal?

texts:
I was previously using a 2N2222A transistor with a small dc motor and it worked fine. As soon as I used it to control the 3A motor, The circuit stopped working.

Is there any way I could control the motor with 3.3v from a Node MCU?

(P.s. I did not use a diode in parallel with the motor, would that be the reason on frying my transistor?)

This is my first project and I'm very new to the world of electronics, any help would be amazing!


texts: An intuitive interpretation of Negative voltage

texts: This seems to be very basic but I am confused about it. I know ground is a point whose potential is zero. Now let's take a piece of wire , and mark a point A on that wire. I said , A has potential of -15 with respect to ground, what does that exactly mean? How can a voltage be lesser than zero? Any explanation in terms of electron? For example we define positive voltage as the force at which electrons ar being pushed in a particular point. Can we have an intuitive Idea about negative voltage using this force or electron concept?


texts:
I have an old electrolux standmixer which I use frequently. A couple of weeks ago I was making bread and the stand mixer were kneading the dough for around 20-25 min and then I turned it off to check the dough. After 10 seconds I tried to turn it back on but it wouldn't start. Since I am a student I cant really afford to buy a new one and since I have an interest in electronics I though I would try to fix it. I screwed the machine apart and there are three main components which are the switch, the circuit board and the motor. I tested the switch and motor and they're both working so the fault must be in the circuit board which is in the picture below.
The two leftmost pins in the top left corner are the pins for the motor and the third is the live wire coming from the switch. Ground is the one in the other corner. Here is another from the back
I tried following the paths on the circuit board and scetched up some of the main circuit which included the motor.

simulate this circuit – Schematic created using CircuitLab
So it's at this point i'm a out on deep water. I've only had a couple of electronics courses so I'm a bit unsure as to what the problem could be. The three arm thingy was a btb10-600b which is after a quick google search turned out to be a 10A triac. The "signal arm" on the triac is connected directly to to pin 16 on the U2010b phase control circuit which is the trigger output pin. I tried shorting the two current leading legs in the triac and the motor span, which leads me to think that either the triac or the U2010B is the problem.
I mainly thought the triac might be the problem due to overheating or something so I soldered on a btb16-600bw triac. I tried to compare the datasheets and they looked quite similar other than the 10 or 16 A rating so I gave it a shot but it still didn't work. I have ordered a U2010B-MY 16 pin which is coming in the mail soon.
So finally my questions:
1:
Does it sound probable that it's either the triac or the U2010b that are to blame or could it be e.g. one of the resistors or capacitors. My analogy is that the triac is a gate ant the U2010B controls the gate so if one of them doesn't work the gate wont open. But could it also be that if e.g. one of the capacitors were broken then the U2010B would never send the signal? Is it more likely that the U2010B is broken or the triac?
2:
I struggled with finding the correct part in close proximity to were I live, so I ordered the btb16-600bw instead of the btb10-600b and the U2010B-MY instead of the U2010B. They look quite similar in the datasheets but are the differences so noticable so it might not work even if I change out the defect part. e.g. like if the triac was fine did I screw something up by changing that part to a btb16-600bw?
3:
Also have anyone ever experienced electrical things working fine and the suddenly wont turn on again after prolonged use? What could be the reason for the broken component? If i fix it should I be careful with too heavy load to avoid heat or could it be something else than heat, like the fact that the machine is pretty old and that it could be just wear and tear of an old part?


texts: 50 ohm D-dot probe measured with 50 ohm scope

texts: I am attempting to measure the signal from a 50 ohm D-dot probe. The manufacturer says to use a 1M ohm scope but I only have a 50 ohm scope. How do I need to set up my tools correctly to receive an accurate measurement? Thank you.


texts: Failing to program Cyclone IV GX device via JTAG

texts:
I just got the aforementioned device and, upon writing a simple program (it compiles) and going into Programmer, when I try to program the device with the .sof file, I see is (Failed) and Quartus' Messages says

Error (209031): Device chain in Chain Description File does not match physical device chain -- expected 1 device(s) but found 2 device(s).

Furthermore, when I try to use the Board Test System that comes with the kit, I get

Java.lang.Exception: No USB Blaster detected.

even though I know 100% that I have the USB blaster driver installed, and have been using it with a different Cyclone II board.

I suspect there might be some sort of mismatch between the version of Quartus I have (13sp1) and the version of Quartus indicated by the development kit that comes with my device (12.1) but I cannot be sure.


texts: In RFID, are there tag modules that give the user a choice of different outputs?

texts:
I look for an RFID tag that gives you the option to 'choose the output'. For example, you want to choose an RFID-output from a list of X possible outputs using a multi-directional switch with X directions.

Does something like that exist? What resolutions of X are there available? How small can it be?

If not, how could you go about designing the thing? Just slide the antenna over the desired Chip from a number of X chips and do some debouncing? Or use just one chip but connect one out of its X inputs with a further circuit and a debounce?! (and what type of circuit?)

Furthermore, how does one tackle higher resolutions for X without making it bulky (as there is just not enough room to make it work with debouncing and different chips and the mechanics and all)?


texts: How can these two motors produce the same torque if their volt/amp ratings are different and their watts/RPM are the same

texts:
My rudimentary understanding of a DC brushed motor is speed is proportional to voltage and torque is proportional current. Therefore a 36 volt 500 watt motor should have a higher RPM rating and a lower torque rating than a 24 volt 500 watt motor which should have more torque but less RPMs.

However, the datasheet suggests that even though the current ratings vary between the two voltages (as expected), the speed and the torque are the same, implying that torque is a function of watts rather than current.
Question 1. How can the voltage / current be different and the speed / torque be the same?
Question 2 Practically speaking, will the 36 volt motor be preferable to purchase since I would get the same torque as the 24V motor but less current (and the heat this produces) going through my circuit?
I know I have misunderstood something.
All help appreciated.


texts: Switching a sensor in or out (between 2 microcontrollers)

texts:
I have some PT1000 RTD Temperature sensors between  -10deg and +120deg C.
in an existing application.
but the controller reading this is undocumented and now obsolete.

I want to be able to use the existing sensor in situ, but switch the sensor from the existing controller, so i can read it from my own microcontroller every 5 or 10 minutes.

the existing controller will tolerate the sensor being disconnected for up to 30 seconds before it alerts..and resets the alert once its reconnected.

so I could just use a relay to switch the pair of wires going to the sensor.
but the relay probably wont last long.

so is there a better method i can use to achieve the same effect.

for example,
Either
An electronic (rather than electro-mechanical) method of switching the sensor between the 2 controllers.

or alternatively
A method by where the sensor could be read by my microcontroller,
but the reading then 'spoofed' to the existing controller in some way.

the sensor in question is a PT1000 RTD based sensor which changes resistance by +3.91 Ohm for each increase of 1 Deg C.

thanks
Rich


texts: Execution of a piece of code in embedded

texts:
Can anyone explain to me step by step
What is the result of executing the code below:
DDRB = 0;
unsigned char temp;
temp = (PINB & (1 << 4)) >> 4;


texts: What is this go-no go function in some oscilloscopes and how can I use it?

texts:
I have seen some oscilloscopes with this option (go-no go function), but I don't know what it is.

I couldn't find anything about it in my searches.

What is it?


texts: How can I increase the overall gain on this circuit?

texts: This is a circuit from Nicholus Boscorelli's Stompbox Cookbook, page 194. The circuit introduces crossover distortion. i built it and it works fine. However it won't go past unity gain which wouldn't be a problem but as the potentiometer is turned to increase the distortion, the volume decreases. What can I change in the circuit to increase the gain?


texts: I have contacts that are so close together I'm either bridging them, or melting the neighboring one. What am I missing?


texts: PIC16F877 pin functions order in pin name

texts:
For example, one pin's name is RA2/AN2/VREF so I wondered what the order is of the functions on this pin. Are they the same or left to right or reverse?

Thank you for your answer.


texts:
in this code :
//at89s52 processor 16.000Mhz oscillator
#include<REG52.h>

sbit IN1 = P1^0;
sbit IN2 = P1^1;
sbit IN3 = P1^2;
sbit IN4 = P1^3;

sbit north = P0^0;
sbit south = P0^1;
sbit east = P0^2;
sbit west = P0^3;

sbit northE = P0^4;
sbit northW = P0^5;
sbit southE = P0^6;
sbit southW = P0^7;
sbit pump = P3^3;
 sbit led = P1^0;
void delay(int a)
{
    int i;
    for(i = 0; i<a;i++)
    {
TH0 = 0xFA;
        TL0 = 0xCA;
        TR0 = 1;
        while(TF0 == 1)
        {
            TF0 = 0;
            TR0 = 0;
        }
    }
}
        void SerialBegin()
        {
            TMOD = 0x21; // timer 0 mode 1 & timer 1 mode 2
            SCON = 0x50;
            TH1 = 0xF7;  //4800bit per second
            TR1 = 1;
        }
        void SerialLetter(char t)
        {
    SBUF = t;
            while(!TI);
            TI = 0;
            //send ASCII letter
        }
        void SerialPrint(char *q)
        {
            while(*q)
            {
                SerialLetter(*q++);
            }
        } //send entire string
        int SerialRead(void)
        {
            while(!RI);
            RI = 0;
            return(SBUF);
        } // value of reading Serial
        int dat;
        int count = 0;

        void main()
        {
            SerialBegin();
            SerialPrint("Made by Kiro Using AT89S52 \n");
            P1 = 0x00;
            P2 = 0x00;
            P0 = 0xFF;
            pump = 0x00;
IE = 0x81;
IT0 = 0;

            while(1)
            {
                dat = SerialRead();
                switch(dat)
                {
                    case 'F':
                    SerialPrint("Forward");
                    IN1 = 1;
                    IN2 = 0;
                    IN3 = 1;
                    IN4 = 0;
                    break;

                    case 'B':
                    SerialPrint("Backward");
                    IN1 = 0;
                    IN2 = 1;
                    IN3 = 0;
                    IN4 = 1;
                  break;

                    case 'R':
                    SerialPrint("Turning Right");
                    IN1 = 0;
                    IN2 = 0;
                    IN3 = 1;
                    IN4 = 0;
                  break;

                    case 'L':
                    SerialPrint("Turning Left");
                    IN1 = 1;
                    IN2 = 0;
                    IN3 = 0;
                    IN4 = 0;
                  break;

                    case 'S':
                    SerialPrint("Stopped");
                    IN1 = 0;
                    IN2 = 0;
                    IN3 = 0;
                    IN4 = 0;
          break;
}
}
}
        void ISR() interrupt 0
        {
            if(south == 1)
            {
                pump = 1;
            SerialPrint("*SR255G0B0*");
            delay(5);
                pump = 0;
                SerialPrint("*SR0G0B0*");
            }
            if(north == 1)
            {
                pump = 1;
            SerialPrint("*NR255G0B0*");
            delay(5);
                pump = 0;
                SerialPrint("*NR0G0B0*");
            }
            if(east == 1)
            {
                pump = 1;
            SerialPrint("*ER255G0B0*");
            delay(5);
                pump = 0;
                SerialPrint("*ER0G0B0*");
            }
        }

The pump is working properly in Proteus simulator

After uploading the code to the MCU , the pump didn't work like what happened in Proteus.

What should I do to make the pump work ?


texts:
So I figured I need an audio range function generator and was thinking of generating a square wave with a 555 and then using op-amps to integrate it into a triangle and sine. Since I happen to have some LM339s laying around and I was thinking, I could use these. All my searches yielded only talk about why you should not use opamps as comparators, but not the other way around.

So hence my question, what are the drawbacks of using a comparator with pull up resistor as an op-amp integrator? Should I just use 2 or 3 discrete 741s instead?

Also the design frequencies are low, some 40 to maybe a few kilo Hz, mainly for testing linearities and distortion of different circuits(I got tired of using the old computer's sound card method)


texts: Need help in understanding the working of battery level indicator


texts: Will the large gate current when turning on/off power mosfets with gate drivers cause problem to limited current power supply?

texts:
I have a idea using Arduino to control power mosfets(CSD18532). After considered some problems about wiring power mosfets directly to Arduino pin, like considerable slow switching time, I turned to using a gate driver IC(LM5114) between Arduino and the power mosfet. I think I could use the picture below taking from LM5114 datasheet page 10 to used as my schematic. The VDD on LM5114 will wire to Arduino's +5 volts power supply directly, while the PWM wiring to Arduino pin.

I learned from a TI's appnote that when turning on/off power mosfet, the gate current is considerably large(I roughly searched the internet, and got answers like 1 amp or so...). So my basic question is that will it be ok for a USB powered device like Arduino to power the gate driver IC's VDD through its +5 volts power supply directly? I know that USB port can only source 500mA...

With this question, I found TI's LM5114 Evaluation Board's schematic on page 8. Although I don't know the schematic clearly, I found that LM5114's VDD directly coming from a 50mA LDO. I used the equation from previous appnote(page 9):

So the IG is roughly: (5 - 1.4)/2 + 1.5 + 1 = 800mA. Will the relatively large gate current cause damage to the 50mA LDO(LP2982)?


texts: From what pitch should I consider ENIG finish

texts:
My design (4-layer, FR4, 1.6mm) has a couple of ICs with 0.5mm pitch pads and some LEDs with 0.4mm pitch pads, very small LEDs.
Should I consider ENIG (more expensive) or will HASL do the job?
I read that when doing BGA it is most important to have a board finish with ENIG but what is the pitch limit for QFN that HASL finish is good enough? Is there a difference when using leaded or non-leaded solder?

Thanks.


texts:
I´m making a small box that has to be completely sealed with no holes on them. On the inside of the box is a circuit board  which requires 9V DC plug and there is also a USB connection from the board. So basically, I have to lead a USB cable and a 9V DC plug out of the sealed box.

What is an efficient way to do that? Can I do combine the wiring somehow and lead them through a single hole on the box?

How is this generally done?


texts: Microcontroller signal multiplexing using transistors

texts:
I am working on a project which involves reading a 0-5V voltage measure (related to custom-made encoders made of slide potentiometers) to ADC on STM32F103. However, I have only one pin with ADC available. Anyway - i have 3 measurements which I would like to multiplex - and there comes the problem. The measures do not need to bo switched with high frequency, they will be switched only when needed to be read.

I was thinking about using NPN transistors, although I am not sure if I have used them correctly. Anyway - is it a good idea? Are there any other possibilities?

Thanks.


texts: Smallest circuit for Ultrasonic Mist Maker or humidifier

texts:
I am working on Ultrasonic Mist Maker or humidifier circuit, but does not found any good circuit.

As search on google that we have to make about frequency 1.6MHz to convert water into mist. using these type of piezoelectric transducer

i found some circuits like this one

But its very big circuit with many components used.
We require small size circuit with lowest possible components used.


texts: How to create continuously incrementing counter in structural modelling?

texts:
I made the below counter and stimulus/testbench and it works fine.

module half_adder(
    input in1,
    input in2,
    output sum,
    output carry
    );
 xor(sum,in1,in2);
 and(carry,in1,in2);
endmodule

module counter(
   input  [3:0] a,
    input  clk,
    input add,
    output [3:0] r
);
wire c0,c1,c2,c3;

half_adder h1(a[0],add,r[0],c0);
half_adder h2(a[1],c0,r[1],c1);
half_adder h3(a[2],c1,r[2],c2);
half_adder h4(a[3],c2,r[3],c3);

endmodule

module stimulus;
reg [3:0]value_i;
wire [3:0]value_o;
reg clk,reset,count_i,preset,timeout_o,add;

counter co1(value_i,clk,add,value_o);
initial
begin
value_i = 4'h0;
clk = 1;
reset=0;
add = 1;
end

always
#20 clk = !clk;
endmodule

Now I would like to increment continuously until 4'hF and stop. The logic is to perform a reduction AND on the value_o and update the add to be 1.

I have tried using a while loop like

while((&value_o)==0)
add = 1;

But Xilinx Vivado Simulation just gave value_o to be 1 always.

My next idea is to use a generate loop. Like

generate
if((&value_o)==0)
 counter co2(value_o,clk,1,value_o2);

But I do not know how to update value_i of co2 to be value_o of co1.And where should the generate loop be placed? I assume it should be in it's own? (if it makes sense). What other ways can I do this?


texts: Can a floating capacitor terminal be used to collect electrons?

texts:
I want to collect charge from an electron beam source. For that, I'm proposing to put a floating capacitor with its bottom terminal floating and directly exposed to the electron beam gun. The top terminal would be connected to a transconductance amplifier.
Do you think that it will work? What considerations or modifications would you suggest?


texts: What's the point of DMA in embedded CPU's?

texts: I was doing a project recently with the mbed (LPC1768), using the DAC to output various waves. I read parts of the datasheet, and it talked about how it had DMA for a lot of the peripherals. This seemed like it would be useful, but on further reading, I found that the DMA used the same data bus as the cpu (which I guess is normal). Does this mean that the CPU cant interact with any of the memories while the DAC is getting data? Also, since the DAC didn't have a buffer (as far as i could tell) and therefore has to DMA very often, whats the point of DMA? If the CPU can't do memory transactions, can it do anything?


texts: Digitally-Controlled Analog Processing for VGA Video Signal?

texts:
A few months ago, I replaced the dead fluorescent backlight of an LCD computer monitor with an 8-bit-per-channel RGB LED strip, and built a controller for it from an AVR microcontroller that talks to the same Raspberry Pi that drives the screen.  This allows me to dim the display from a shell script or a manual potentiometer or whatever.  So far so good.

Now that I've used it for a while in very low ambient light, I want to dim it even more, but the minimum setting for the LED strip is still too bright.  Even dithering barely-on yellow (RRGGBB = 020100) vs. off for adjacent "pixels" isn't enough, and using red-only (RRGGBB = 010000) is almost useless as it only shows that channel of a color image.

The monitor itself only accepts VGA, so I have an HDMI > VGA converter between it and the Pi.  And since I have that analog signal to work with, I eventually came up with this concept:

simulate this circuit – Schematic created using CircuitLab

All three colors operate together, so there are effectively 2 proportional controls and 1 binary control.  All managed by the AVR in addition to the backlight itself.
The sync's and other signals are wired straight through, unchanged.

I looked on DigiKey for digipots and voltage-controlled-amplifiers that would work for a ~62MHz analog signal (1920 x 1080 x 60Hz, alternating black and white), but didn't find anything even close.  (I didn't look for opamps yet; I'm pretty sure that those exist.)  I also thought about doing those functions in the Pi, before the HDMI > VGA converter, but decided that I'd rather like a hardware solution if possible.

Are there digipots or VCA's that can do that?
Or maybe a different circuit design or processing technique that I'm so far unaware of?
(a PWM chopper might be a challenge too: >10x signal freq with LPF gives >0.62GHz PWM)

Maybe a chip that I haven't found yet, that "just does this"?

Note: The schematic above is just a concept that would technically work with ideal parts.  It has some glaring omissions (like impedance matching), and is not a final design by any means.


texts: Can someone explain part of this wiring diagram to me?

texts:
In the 208/220v diagrams for 2 pole 3 wire outlets here(http://www.automationdirect.com/static/specs/wiringdevicesnemawiring.pdf) there have an arrow between the two wires that bring in 120v each and label the arrow 250 (or 208) volts. Are they just saying that there is 250v supplied total by these two legs, or that there is 250v between these legs?

I think it is saying that there is 250v supplied total, as I think there's 0v between the legs, unless the outlet is doing something like switching polarity?

Thus reason I am unsure is because the diagrams for 125v use the same arrow to show that there is a 125v difference between the hot wire and ground, so if they are not using the symbol in two different ways then the 250v diagram says that there is 250v between the two legs that have 125v each, which I don't see how that happens unless there is a built in Op amp or something...

Thanks.


texts: How to calculate the conduction losses diodes in each stage

texts: how I can calculate the power losses for each step in The voltage multiplier (3 steps). I work in low voltage and  power so some milliwatt losses are important in my system how I can calculate the power losses of the capacitors in each stage


texts: Using 250V PS2 Power Supply to power Raspberry Pi 3

texts:
I'm building a RetroPi Box from an old Playstation 2, and I'd love to recycle as much of the PS2 components as possible.

My PS2 (first generation model) has a power switch for its 250V built-in power supply. Since hooking this up to the Pi would fry it, I thought I'd simply plug a stripped USB charger in between the two.

My train of thought was that since European sockets also supply around 220-240V, the usb charger parts would take care of the Volt conversion for me.

Is that right? If not, do I require similar components as this answer suggests?

The raspberry pi requires around 4-5V to run properly with USB devices attached.


texts:
I'm using a smartphone.

When I turn off the cellular data or my mobile phone, I can still call and send SMS.
Does that mean in this case the mobile using GSM? How can I know if it is GSM or GPRS? And which technique is used TDMA or CDMA?

When I turn on the cellular data I see for examle 3G or 4G or LTE active.
In this case, does that mean GSM or GPRS is inactive and voice and SMS is also
sent via 3G or GSM is separately always active?


texts: What is the purpose /name of this CMOS gate configuration?

texts: I have tried search via google images, but it's not good at recognizing line drawings


texts: ESD - Is it safe to connect yourself to an electrical outlet?

texts:
Is it safe to connect yourself to an electrical outlet?

Either directly or indirectly.

I would prefer to not connect myself directly to an electrical outlet, via (as I've heard) attaching a wrist strap to the middle screw of an outlet.

Though I am wondering about connecting more indirectly.

I am building a computer, that has a fully painted case.  I have heard of a way to ground using the computer's power supply by:

Plug in power supply to wall outlet, turn power supply OFF, partially unscrew one of the four power supply screws (that hold it onto the computer case), then attach the anti-static wrist strap to the threads of the unscrewed screw.

Is that safe, in regards to indirectly connecting yourself to a wall outlet?

I would prefer a standalone ESD setup, that doesn't involve a wall outlet, however I have not yet heard of any ways to do so.

Thank you very much for helping with this.


texts:
I want to detect the impact of a ball against a table tennis racket.

I'm currently using Piezo discs tightly fixed in the racket wood.

However, in addition to correctly detect impact, the sensor also detects sudden accelerations in the racket. As an example, it is very common to make a fast movement backwards just before hitting the ball.

My approach is very naive: I'm reading the ADC as fast as possible and if the average of the last 10 measures reaches a threshold, I consider the impact detected. (I tried other numbers besides 10.)

Questions:

Is there a better sensor for this purpose?
If not, how can I differentiate (or filter out) sudden movements from ball impacts.


texts: How to compute dissipation of switching regulator considering the input?

texts:
I want to use a 5V 500mA to my circuit, also this will have a current spike for 1A. The input will be from 9V - 36V. I have reviewed the difference between the linear and switching regulator and obviously I should be using the switching regulator.
How suitable is this switching regulator for my application with a real 36V input?

https://www.digikey.com/products/en?keywords=OKI-78SR-5%2F1.5-W36-C

This is on its datasheet.

I know that switching has less power dissipation than linear, but how do you compute the power required, or power dissipation, power loss considering the input, ouput voltage and the output current on a switching regulator?

Will I able to use it on 36V input to have a really 5V, 1A output?


texts: If i had a good knowledge in Java programming and know some information about Microcontroller, Can i begin to learn embedded linux? if not, how can i start in this field?


texts: Electric grinder not working with my power inverter

texts:
I have these devices.

Sealed type car battery (35Ah)
1000W Power Inverter (Modified Sine Wave, Model:Suder)
2 Solar Panels (37V, 8.2Ampiers, 310W each)
Solar Charge controller(30A)

My Grinder is 230V, 620W device.

I use solar panels to charge my battery.

I did this:

Fully charged my battery using solar panels. Solar charge controller showed that battery is full in LCD display.
I connected my inverter to battery while charging with solar panels.
Plugged my grinder to inverter.
Turned on inverter power button. Inverter is working normally.
Turned on my grinder, Then grinder blade is slowly turned around and stoped. and also in my inverter, a red bulb named fault is lit. But battery level is still full.

What is the reason for that? I am bit confused because as i calculated, my grinder need only 2.69Ampiers. But battery already have 35Ah fully filled. And also grinder need only 620W and my Inverter outputs 1000W.

And also my inverter is works with CFL Bulbs, Cieling fans etc. without any problem. And also my grinder works normally with Normal government electricity line.

Can anyone tell me whats the wrong I got?


texts: In theory, is the position derived from accelerometer absolute?

texts: I recently found multiple research papers that say that in theory double integral of accelerometer data gives a position of the device. Does that refer to absolute position (like the one given by a GPS)? or for example starting position and then relative position to the starting position?Thank you for helping me clarify this.


texts: Control software for three phase induction motor

texts:
I have been writing a control software for field oriented control of three phase induction motor.
As far as the platform I have been using the FreeRTOS real time operating system. My plan is to
calculate the whole torque control loop in the interrupt service routine associated with
end of the A/D conversion interrupt which will be invoked regularly with 100 us period. Besides the
torque control loop the associated isr will be also responsible for implementation of software
oscilloscope. Operation of the software oscilloscope will be configurable in such a manner that
it will be possible to set how many samples are reserved for the pre-trigger, to set the trigger variable
and trigger condition (given variable greater than or less than the specified value).
My question is how to pass the oscilloscope configuration into the interrupt service routine (more precisely into the oscilloscope module which is invoked from the isr) in such a manner that it is ensured that in all cases the oscilloscope works with consistent configuration i.e. always new pre-trigger setting, new trigger variable and new trigger condition are used together (it is not allowed to use let´s say new pre-trigger setting, new trigger variable with old trigger condition).
My idea was to exploit disabling of the interrupts in case configuration of the oscilloscope will being
changed. But I have doubts regarding the negative impact on the torque control loop execution. Does anybody have better idea how to resolve that? Thanks in advance for any ideas.


texts:
I have a circuit which drives a latching selonoid valve(valve changes state for every 50ms pulse)

Below there is an easy go schematic of the circuit. Basically a 3.7V LiPo Battery supplies for 3.3V mcu regulator and a boost converter of 9V's (LM2623).

To switch the valve mcu enables the boost converter and waits for 10ms for stabile 9V. And then set drive pulses to valve driver.

When I connect the board to MSP430 Launchpad(debugger, vcc=3.5V) and in debug state; if I run the code, valve perfectly switches between state. In the switching time, voltage on coil only decreases to ~7V.

When I disconnect the debugger and run with only battery, code tries to swith the valve but, it not switches. And voltage on coil decreases till ~5v or so.

How can this extra voltage decrease can be compansated. There is already 100uF connected to valve driver supply.

simulate this circuit – Schematic created using CircuitLab


texts: Why doesn't an electric charge use up all its potential energy travelling from positive to negative terminal?

texts: When an electric charge flows from high potential (positive terminal of battery) to low potential (negative terminal of battery), why doesn't the charge use up all of its potential energy at the start to move to the negative terminal? Why is there still enough energy to power a light bulb? E.g. A ball which is lifted above the ground has potential energy and all the energy is converted to kinetic energy to move to the ground when released. Why isn't all the electric potential energy of the charge converted to energy to move to the negative terminal as well? Where does extra energy to power a light bulb come from?


texts:
There is a 12V (max 8A), voltage regulated power supply which is directly connected to a pure resistive lamp as shown in Figure1 below(sorry for primitive drawings):

I'm planning to monitor the power consumption of by a DAQ device. My DAQ can handle up to 10V so if I use a 1 ohm resistor in series(Rshunt) for the current's data acquisition(between a and b) and measure the voltage across the lamp(between b and c) I was thinking to log the power consumption since the power = I*V.

My question are:

1-)Is my setup fine? Would 1 ohm resistor handle that much current?

2-)If not what kind of device would you suggest which I can log the power?


texts: What does the 20-80A rating on an energy meter mean?

texts:
On the energy meter nameplate is a current rating 20-80A, which I can assume has something to do with max current.
I'm particularly interested in the "20" part, though. What does this rating mean? I don't want to assume that this 20 is the minimum current that the meter can measure because it really wouldn't make sense to me. Internet articles aren't really clear on this, so I'm hoping I can get clarity on the matter.


texts: How can I separate the sync signal from a composite video signal?

texts:
I have a small device (based on an AVR microprocessor) that outputs a Black & White composite PAL video signal, designed to be plugged into a TV. I also have an old Amstrad CTM644 monitor and want to know if the two can be connected together.

The Amstrad monitor has a six pin DIN input with the following pins

Pin No. Signal Name Description
1           R           Red analogue signal
2           G           Green analogue signal
3           B           Blue analogue signal
4           Sync        Composite Sync
5           GND         Common
6           LUM         Luminance

Since the image produced by the device is only black and white is it possible to build a very simple circuit to separate the luminance and sync, or is it more complex than this?


texts: Lower resistance resistor in place of a higher resistance one

texts: I drew this small circuit from a design a friend gave me to blink an LED, but I am missing a certain component. I am missing a 12KΩ resistor. Can I get away with a 10KΩ resistor in its place?


texts:
Ben Eater's 8-Bit Computer  project calls for 8 "4-bit D-type register". Is it ok to use the CMOS version, the CD4076BMTE4?http://bg-electronics.de/datenblaetter/Schaltkreise/CD4076B.pdf

I have heard that sometimes the voltage varies too much. The orignal design asks for the 74LS173. http://www.ti.com/lit/ds/symlink/sn54173.pdf

Also, can you use a bidirectional register, like the 74S194, and set it to go one way? http://www.ti.com/product/SN74LS194A

Lastly, can an 8 bit shift register IC, like the 74hc595, be used with four bits or does the chip require 8 bits to work properly?
http://www.ti.com/lit/ds/symlink/sn74hc595.pdf

Sorry, for asking so many questions at once.


texts:
I'm planning to use the AD623 in-amp for voltage-difference amplification in a project, but I'm having some issues with getting it to work as wanted.
Right now I'm actually just testing the in-amp so that I get to see how it works.
My voltage supply is 7V, my gain resistor is 220k and my input is 3.3V.
With this gain resistor I should get a gain of about 1.5, but my output is at 6.5V (gain = 2.) The output doesn't change even if I change the value of the resistor.
What am I doing wrong?


texts: control systems - state space representation using transfer functions

texts:
I am trying to manually get the state space representation of an RLC network. I often end up with a bunch of differential equations that I can't relate to each other. I think it would be easier to just get the transfer function between the output and the input for the system and then convert the transfer function to a state space. Can I always do this ? Using transfer functions always gives a different state space representation and I just want to make sure this is fine.

Here's my attempt at using a transfer function to get a state space representation:


texts: How to avoid input/output conflicts with a bus

texts:
How does a system bus work?

I don't understand how can a circuit avoid input/output issues with a bus. I included an image to better explain my thinking.

The circuit has 2 general purpose registers connected to a system bus. The left wires of each GP register is input and the right wires is output. Currently, the input is going inside the output, causing logisim to mark the wire red (error). What are the solutions to avoid this?

Here is the black-box for the registers.


texts: I have some 12 V motors, and the corresponding motors controlers like these here http://imgur.com/XBEww. Every other 12 V power supply I have seen is either very expensive or has extremely low amps, where even a $20 computer power supply will provide like 10 amps at 12 volts.  Is it possible to use a computer power supply to control some 12 V motors with my Arduino and these motor controlers?


texts: What is the purpose of this AND gate in an audio amplifier

texts:
I am analyzing the below audio amplifier circuit (from 4D Systems) and I am trying to figure out, what is the purpose of the positive AND gate (SN74LVC1G08) which connects to the audio input signal?

Audio input is PWM format.


texts:
the questions goes like this: model ideal diode (0.75V battery and 100 Ohms resistance)  and then calculate the average V0.
I know how to add the 0.75V but how can I add the resistance to the diode? just in series I suppose?


texts: Can I use snubber capacitors on smps output filter?

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I'm working on a full bridge dc-dc converter and I got only snubber capacitors and no time for ordering new ones.

I got 350V-5.7A output, fsw is 30kHz

Capacitor: https://alconelectronics.com/wp-content/uploads/2020/01/IGBT-Snubber-Capacitors-Datasheet-KP-6.pdf.pdf

1uf-1200V rated, 6 in parallel

can I use this one for output filter capacitor?


texts: Opamp isolation buffer behind phototransistor

texts:
Part of a PCB I designed looks like this:

Simple phototransistor with a resistor to measure the voltage over. More light => more voltage over the resistor.

However, the circuit behind the output doesn't like it when the impedance of it's input is too high. Lacking a better idea, I decided to try what effect an opamp as isolation buffer would have:

The opamp (LM358N) got hot and didn't perform as expected.

VDD is 3.3V, not even close to the maximum Vin the LM358 is rated for.

Did I cut a corner I shouldn't have cut or did I make a seriously stupid mistake here?

To avoid any confusion: the circuit without opamp works exactly as intended. Just not in combination with the next stage of the design.


texts: Controllability and observability from given transfer function

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Is it possible to determine whether system is uncontrollable or unobservable or both  from given transfer function in which there is pole zero cancellation?
for ex.transfer function like this
Or it impossible to determine it's controllability and observability from given transfer function until it is already defined in State space model?
As @AJN pointed out for more clarity I'm adding one more example


texts: Difference between analog signal and battery voltage

texts:
I want to find out if using an analogue sensor is feasible in my noisy environment by running some signal integrity tests before I buy it. Because I don`t have the sensor yet, I need to simulate its output. This can be assumed to be a constant DC voltage, since it will change very slowly. A reasonable value for this voltage is 2.25VDC.

My approach to model my sensor is to take a 9V battery and load it with four 220K ohm resistors in series. I will use the potential difference between the last resistor and ground (2.25V) to model my sensor`s analog output, and run my tests with it.

To make this more clear, an example of a test I will run is to use one ADC module to measure the voltage across the last resistor in the potential divider, and another ADC module to measure the voltage across the wires of the other end of a slip ring connected across that last resistor while it is rotating. Some more background to understand the application if you're curious is at this question.

My question is can an analogue signal be modeled by a battery? What is the theoretical difference between an analogue signal and the voltage across a battery`s terminals other than the source resistance?

Thanks for helping a beginner to signal processing!


texts:
I purchased a 12v Timer Relay that has no instructions but after messing around with it I have it somewhat programmed. My issue now is using the trigger inputs, the relay information states that the trigger type is "Short". What does this mean? I am trying to trigger the relay from a TEMT6000 light sensor https://www.sparkfun.com/products/8688, when the light goes off I want the relay to trigger. Right now the only way I can get the relay to trigger is to short the SIG and GND wires at the sensor.

I have figured out most of the timer and how it works. With the light on the voltage out of the sensor is 4.85 and with it off (as best as I can darken the room) 2.15v. However at 2.15v it doesn't trigger the relay, how do I pull the trigger lower?


texts: Digital Multimeter "Continuity test" only one single beep

texts: Well I have two electronic circuit, one is broken and the other is solid and working. While I am making Continuity test with Fluke Multimeter on working electronic circuit, the bip voice heared only once time. but broken part is giving continutiy bip voice. How can a digital multimeter give only once bip voice. what does it mean.