texts: Sending identification signal with IR or RF

texts:
Is there any way to build a device capable of sending an ID signal with IR or RF?

For example, imagine I want my TV to know whose remote is being used (assuming everyone has a different remote).

I thought about assigning a different frequency to each "user", but if we had one million users, that method would me impossible.

My second idea was to send a second signal via WiFi, which based on GPS location would know if I'm close enough to the TV to use the IR signal too.

The TV example is only an idea, not the purpose I'm seeking.

Thank you for your time.

Gabriel.


texts: Help with demonstrating the meaning of this information

texts:
Regarding the following information about open drain and push pull configurations:

The advantage of the push-pull output is the higher speed, because the
line is driven both ways. With the pull up the line can only rise as
fast as the RC time constant allows. The R is the pull up, the C is
the parasitic capacitance, including the pin capacitance and the board
capacitance.
The push-pull can typically source more current. With the open-drain the current is limited by the R and R cannot be made very
small, because the lower transistor has to sink that current when the
output is low; that means higher power consumption.
However, the open-drain allows you to short several outputs together, with a common pull up. This is called an wired-OR
connection. Now you can drive the output low with any of the IO pins.
To drive it high all outputs have to be high. This is advantageous in
some situations, because it eliminates the external gates that would
otherwise be required.

I'm stuck with understanding two parts above:
1-) "With the open-drain the current is limited by the R and R cannot be made very small" What is meant by that?
2-) Regarding  wired-OR: "This is advantageous in some situations, because it eliminates the external gates that would otherwise be required." Why would external gates required in push-pull case
Can these be explained by using circuit diagrams?


texts: Is it safe to build a floatable speaker?

texts:
I'm thinking of building a floatable speaker to float along beside me in a lake or a small river while tubing.  I've got some speakers and the following 12V amp:

DROK Amplify Module Audio Component Amplifier,TDA7297 (TDA7297 15W+15W)

and I was thinking of using a power bank capable of 12v output to power it, such as this:

XTPower MP-10000 External Battery Pack with 10000mAh using dual USB 5V and DC 9V / 12V 2A output

I was thinking of putting this all in a waterproof pelican box, drilling holes for the speakers, and putting a thin plastic membrane over the speaker cone to prevent water getting in, and throwing in a silica gel packet to absorb moisture.  The speaker cones would also be covered by a metal mesh to protect the plastic membrane, and they would be silicone-sealed to the waterproof box.  I'd have this floating along with me in a small river or a lake.  Theoretically, no water will get in.  So my questions are:

If water does get in, is it going to harm anyone in the water?  I can accept damage to the hardware, but I want it to be safe.
I know lithium batteries don't mix well with water,  and I think that's what is inside of power banks.  I've seen waterproof power banks, but the only ones I can find can only put out 5V.  Is there a better and safer power source?
Is this totally unsafe?


texts: Sigma-Delta ADC with variable reference DAC

texts:
Is it possible to create ADC with variable range by having variable reference for 1-bit DAC in sigma-delta A/D converter.
Here is simplified sigma-delta A/D converter with variable reference for 1-bit DAC:


texts: Parallel connection of DC DC Converters with different output to charge the battery

texts:
Generally, in connecting power supplies parallel one can follow current control or droop control rather than voltage control to regulate the output of a dc dc converter. If the output of both the converters are connected together.
As shown in the figure
Then we can implement those current controlling methods mentioned above.
What if the converters had different output.
The figure shows with different output
What kind of strategy do we use here current or voltage.
I am thinking that the converter output terminals are not connected together and there is no need to see how much current flows through each converter and voltage controlled mode will be used. Is this correct or wrong?
Mostly the dc dc converter evaluation boards available in the market control their output voltage using potentiometer, resistor trimming, I2C programmable. What kind of strategy should be used to control with Microcontroller using voltage divider, current amplifiers, ADC, PWM generation. There is I2C but the complexity of the coding will be increased. I am not much into coding. For suppose as shown in the figure both the converters are given 36V input and charge the batteries connected to each conveeter output. How can I control the charging here digitally?


texts: Why do I need to "ground" my guitar pickup to the guitar bridge

texts: When wiring my guitar pickup, I connected the ground wire to the ground of the output jack. After hooking that up, I would hear a hum unless I soldered a wire from the metal bridge of the guitar (where the strings enter the guitar body) to the same ground of the output jack. Why did I need to connect the bridge to ground?


texts: I am confused by the "substrate height" and "trace thickness" when I am calculating my microstrip width on here . From manufacturer, I got Does the "out layer copper thickness" refer to "trace thickness" and "inner layer copper thickness" refer to "substrate height"? The board is FR4 with thickness is 0.8mm. I am trying to get 50 ohm impedance. Thank you!


texts: electronic switch (like MOSFET, but without diode?)

texts:
An n-channel MOSFET is an inexpensive way to connect and disconnect circuits to 0V.  But if I have a fixed voltage (in this case, 2.5V) and want to connect  fixed resistances of higher or lower voltage, the diode in the MOSFET will interfere?

There are analog switches, but they are expensive by comparison.  I am looking for the equivalent of an inexpensive MOSFET that is 1Mohm when the gate is 0V, 0.5ohm or less when the gate is 5V (or 10V) above the reference voltage, but I want to handle voltages both higher and lower than the reference voltage.

The power in the circuit is tiny, in the milliwatt range, so dissipation is not an issue.

Is there any such device?

Here is an op amp circuit.  It will allow variable gain depending on the whether the gates of M1 and M2 are high or low.  This works when the resistors are connected to ground, and it should work when the resistors are connected to 2.5V as shown, as long as Vin is higher than 2.5V.  I would like to know what to do if Vin is less than 2.5V.


texts:
I'm using an LM386 for voice amplification. The transmitter transmits the signal from the tank circuit on the correct frequency but without voice.
I'm a beginner and a hobbyist and I'm still trying to understand the process.

I tried using a power supply from 3,3 V up to 9V and it made no diffetence.
When I touch the microphone the signal modulates a bit.
The circuit is tested currently on a breadboard and soldered on a perfboard.
I have an SDR, an osciloscope and a signal generator.

Perf board:


texts:
I'm looking for a DAC in order to convert a digital signal of 8 bits into an analog signal of 0 to 5 volts with an ideal precision of 1 LSB. It is the first time that I look for a DAC and I'm not an expert in electronics and therefore I have some related questions:

What is the simplest circuit configuration to achieve this precision using for instance this DAC and what is gain adjustment?
Why do we need to add an ampli op at the output of the DAC? And how do you choose it?
Can I set my DAC in write mode all the time if I keep the input bits at the correct level?


texts:
I'm trying to build a smps for a capstone project and am having trouble with the pwm portion of the circuit. When I'm simulating the buck portion it works with 18V dc-400kHZ-43% duty cycle. Now that I think about building the smps I don't know how I'm going to do the pwm. I've looked into gate drivers but don't know where to get the 18v supply. I'm assuming what the input voltage is the output is the same for a gate driver? I'm not trying to get an external power supply to power the gate driver. I was looking into using a microcontroller to do the pwm but it only outputs 5v. I've seen a logic level mosfet and was wondering if I could use this in my circuit and have the microcontroller hooked up to the gate?https://www.sparkfun.com/products/10213

Here's my simulation. I appreciate all the help.


texts: Why is the voltage drop across this 1 ohm resistor being neglected in this practice problem? (Thevenin's Theorem)

texts:
We are given the following circuit and told to calculate the equivalent voltage of everything to the left of the a and b terminals:

It omits the load resistor and lays the circuit out as such for mesh analysis:

It claims that voltage across terminals a and b, the voltage we are looking for, is the same as the potential in between the 4 ohm and 1 ohm resistor. Shouldn't that 1 ohm resistor cause the potential to change a little?


texts:
Looking for some clarification on the proper wiring of an AC/DC optocoupler (HCPL3700, datasheet) when working with 120vac.

From what i read online it looks like a need a resistor on the hot side and a capacitor across the DC inputs. Most of the diagrams i see online specify a 47k ohm resistor on both the hot and neutral side, per the datasheet if i'm reading it right the opto can only handle about 5v on the AC input, but i don't believe that a 47k ohm resistor will drop 120vac to 5vac, it should only drop to 60vac of both resistors are the same. So my question is am i reading the datasheet wrong or am i interpreting the circuit examples i see incorrectly?


texts: Arduino + Ethernet Shield hangs after some time

texts:
I am using an arduino to retrieve some data from a web application. The problem is that after some time it starts to hang.

For testing I used the default EthernetClient sketch and modified it a bit that every few secounds there is send a request to the server to get the information. For testing I don't do anything with the data I get so it does only send the request and retrieve the data.

For testing I use a Arduino Mega 2560  + Ethernet Shield and a Arduino Ethernet board, I experience the problem on both. It runs from 30 minutes up to one day then the whole board freezes. The boards doesn't get hot or anything else.

At first it seams to work but after some undefined time it starts to hang, does anyone have an idea what could cause this? Is there a bug on the arduino or the W5100 Ethernet chip?

Would you try to fix this issue or switch to a Raspberry Pi? Using the watchdog timer is no option because it doen't work on the Mega without changing the bootloader.

UPDATE (Added my loop code, there are no memory issues, I testet that before):

void loop()
{
  if (client.available()) {
    char c = client.read();
    Serial.print(c);
  }

  if (!client.connected()) {
    Serial.println();
    Serial.println("disconnecting.");
    client.stop();

    delay(2000);

    if (client.connect(server, 80)) {
      Serial.println("connected");
      client.println("GET / HTTP/1.0");
      client.println();
    }
  }
}

This is all it does, in the setup there is the default initialization code from the Ethernet demo sketch.

UPDATE 2

Testing with Arduino Mega + WiFi Shield hangs too.

Testing with EtherMega 2560 from freetronics is now running 2 days without any problems I will continue this for min. one week. My only problem with this bord is the price. It's around 100$.


texts: Any qualitative analysis saying RC snubber required or not for High current Buck converters

texts:
I have a design where i am using TPS53355 from TI to generate 0.9V @ 15A from 12V(10V-14V).
For this design, i want to know whether RC Snubber required or not?

as far as i know,

Generally in High current converters inductor will store lot of energy = (1/2)*L*i^2.

If there is a gap between upper MOSFET(Control MOSFET) Off and Lower MOSFET(Sync MOSFET) ON, whole energy stored in inductor will be collapsed suddenly, can develope large spike on LL pin of V = L* di/dt.

In our case, L=0.47uH, Imax = 15A, energy stored in inductor  will be = 0.5*0.47uH*15*15 = 53uJ.

I am not sure in the case of TPS53355, whether any delay between Control MOSFET OFF to SYNC MOSFET ON and the rise and fall times of MOSFET driving circuitry.

if Control MOSFET turnOFF time is approx 50ns.

then V = 0.47uH * 15A/50nSec = 141V. then this much voltage(141-12) has to be withstand by internal MOSFET for the duration where Control MOSFET is OFF and before Sync MOSFET turns ON.
Generally Internal MOSFET's will not have higher breakdown voltages due to their space constraints. How we can be sure that internal MOSFET will not damage for this spike.

in the datasheet of TPS53355, i didn't find these details regarding timings of Turn ON and OFF,But the recommended circuits have Snubber placed in.

There is  "Dead time" between Control MOSFET oFF to Sync MOSFET ON to reduce any shoot through. any details regarding this also helpful.

**One more question is,
In one of the literature,
i read that due to parasitic effects of inductor and capacitor we will have spikes at the switching node (here LL), But i thought because of sudden change in current, voltage spikes will occur at the switching node, am i correct* .*


texts: How to drive the gate of a MOSFET with a PWM like signal

texts: I'M trying to use MOSFET as a driver for my 10W LED with 12V supply. This LED will be used as a transmitter with signal coming from Arduino nano. I'm using IRFZ44N MOSFET with a Vgs(min)=2V and Vgs(max)=4V.  The problem is whenever I give the transmitting signal to gate of the MOSFET it doesnt turn ON to the fullest. The voltage drop across LED would be 6V and across Vds its 6V. When I checked the drop across Vgs the DMM reads only 2V. As of what I read the DMM averages the value for such signals but that should mean the drop across Vgs is aprox. 5v and hence turning on the MOSFET but it doesnt turn ON. Therefore, I tried giving the blink program's 1 second ON and 1 second OFF signal to the gate. What I noticed was the MOSFET turned ON completely with very less Vds and max. voltage drop across the LED but the same isn't true for higher frequency. I would like to know how to drive the mosfet with very high frequency like PWM.


texts: What would prevent me from copying pads (or other components) in Altium?

texts:
I'm attempting to copy and paste several components from one Altium PCB to another. I would like to copy and paste all the components all at once, because they are mounting hardware for another PCB, and their relative layout is crucial.

My problem is that when I select and copy all the components (a header, an outline, and 5 mounting holes/pads), only the outline and header are copied over, not the mounting holes. I've already unlocked all the components, thinking that might've been preventing it, but that didn't help. I've also already closed and rebooted Altium several times.

Any suggestions?


texts: Why don't you ever see a "anything" over (cable type)?

texts:
Possibly an obvious answer, and I'm new to electronics.

You can easily find converters that convert a specific type of signal to another cable to be decompressed on the other end (example, a VGA over coax converter).

In essence, these devices take an analog (or sometimes digital) signal, convert them to a compressed digital signal, send them down a cable with less wires than the input signal had, and then decompress and output as the original signal (at least close enough to the original signal to be acceptable).

Could you make such a converter where it accepts any signal (up to a limited # of wires), be it composite video, analog audio, digital HDMI, or any signal you can imagine, without the device knowing the specific implementation details?

It'd (virtually) be a set of analog to digital converters & compressors on one end, and then digital to analog converters & decompressors on the other.

Would it simply be prohibitively expensive? Or would this not be possible?


texts: PN532 not responding using SPI when issuing antenna-related command

texts:
I've bought a PN532 v1.3 breakout board, to which I communicate in SPI.

I can ask it its firmware number, to which it answers D5 03 32 01 06 07 (PN532 V1.6), which is correct.
It can ask it general status, to which it answers D5 05 00 00 00 80, which sounds correct too.

But when I'm trying to use a antenna-related command, it justs freeze here.

For instance, InListPassiveTarget (4A) or InAutoPoll (60) just freeze, meaning the command cannot even be sent correctly.

What I am doing exactly:

Writing command on the SPI bus
Waiting for READY status on SPI
Getting an ACK frame (00 00 FF 00 FF 00)
Waiting for READY status again. This is where it fails when issing a 4A or 60 command. The status never become ready.

Here is the user manual for the chip I'm using: http://www.nxp.com/documents/user_manual/141520.pdf

I don't understand what am I exaply doing wrong.


texts: Determining voltage and current in a circuit

texts:
The question asks to determine V_x and I_y.

I tried to find it by using KVL in to lower LHS mesh and KCL in the middle node. But, my final value is a contradictory statement(such as I_x equal all real numbers). Any help would be appreciated.

Using KCL in the central node, the current that passes through the 10 ohm resistor is -5-0.1V_x+y(where y is the current that goes through V_x/20 ohms resistor). Then I used KVL in lower LHS mesh, so -50-10(-5-0.1V_x+y)-V_x=0 As you can see V_x cancel and 10y=0 is left. However V_x=20y.


texts: Two questions about testing with HDL designer

texts:
I hope it's okay to ask about specific programs here.

I have successfully created a test bench with HDL designer, and I use Modelsim to simulate. By pressing the Modelsim icon and selecting "through components" I can simulate my design.
My question is about changing small things about my test bench. If I for example change a bit of a signal (be it in the test bench code or one of my design blocks), is there a faster way to update my simulation other than pressing the icon mentioned above (in HDL designer) again and waiting for Modelsim to update?
My current design is synthesized using Precision. After that, my design is programmed into the FPGA using Quartus.
After finishing simulation I would like to test my design using Quartus signalTap, but I have two problems with that:

a. I can not see my state machine states, so I cannot know which state i'm in.

b. When trying to insert some nodes into SignalTap and then programming the FPGA I get an error saying some signals I inserted are missing source.

I assume both problems (a and b) can be solved by using some preserve attribute (as the Precision synthesizer is probably "killing" those signals), but how can I use this attribute if I'm using the graphical tool to create state machines?

If this isn't the solution, then what is?

Thank you!


texts: How to choose a DC-DC Converter for a motor with inrush current? (Theory)

texts:
I am wondering how to choose a DC-DC converter for a motor.

This is a theoretical question for understanding.

For example, if I have a converter that can output 5V with a maximum current of 1A. Assume the input voltage was 24V and the converter can have  a max input voltage of 40V

If the motor, requires 5V and has a rated current of 0.2A, then assuming for a thumb rule, the inrush current was 10x the rated current so 2A). This converter would not be suitable, would it?

Hence how do you select a DC-DC converter for driving motors with the inrush current?

I am currently doing a project that involves a lot of components (can't show the circuit, unfortunately) and so multiple motors, etc but I was unsure on how to choose the DC-DC converter to supply the motors.


texts: Can a linear regulator in shutdown mode have the output in parallel with a switching regulator

texts:
I am trying to design an efficient battery powered circuit using a 3.3V microcontroller (NXP LPC1343). One of the requirements is that the microcontroller periodically read a value from an ADC and based on this, power up the rest of the system to perform some operations. The total power of the system is around 400mA, and the battery is a single cell lithium-ion rated for 850mAh. Therefore, it is desirable to use a switching power supply for maximum efficiency (TI TPS63061).

The software on the micro can be configured to power down the core, leaving only a WDT, which periodically wakes up the rest of the micro to perform the ADC read (while leaving the rest of the system powered down). However, the standby current for the micro is very low, on the order of uA, which from my understanding is too low for the switching regulator to operate (although I could not find a minimum load spec in the datasheet). Also, the input quiescent current for the TPS63061 is up to 60uA, which is much higher than my micro in sleep mode (~2uA), so in either case it is undesirable to leave the switcher powered on. Therefore, my idea is to have a linear low-dropout regulator provide standby power for micro. The micro can then power up the switching regulator once it decides that the rest of the system needs to be powered up.

My question is how to handle this switch-over phase. The LDOs which I looked at have reverse current protection and may be put into standby/shutdown mode. Is this sufficient to not destroy the LDO when the switcher starts working?


texts: How to improve resolution and presicion of sensor reading?

texts:
I'm trying to measure temperature with an arduino uno and a LM335 temperature sensor.
The LM335 can provide differences in temperature between -40C to 100 with a resolution of 10mV. I read the sensor with the (onboard) AVR ADC which is 10-bit.

I use the following conversion to get Celsius from the Kelvin scale that the sensor provides:

\$ ( \frac{M_s * V}{1024.0f} * \frac{1}{0.01f} ) - 273.15f\$ where \$M_s\$ is the measured sample and \$V\$ is the Voltage of my power supply.

I use the "uncalibrated" method of measurement. (currently I don't care about the calibration procedure)

My question is how to improve the measurement perhaps to three decimal points? Is this possible with this sensor and ADC? Can I make multiple measurements perhaps with 2-3 units of sensors with different resistances or with a single unit connected with a multiplexer to different resistance networks so to get a better resolution?
What is the common procedures in cases like this?

EDIT: I would further appreciate if the answers include some information about the difference between accuracy, precision and resolution.

For an example as I understand calibration of the sensor module would affect the accuracy of it. i.e. How close are the sensor readings to the "real" quantities but not its precision. My question was aimed at first to improve the "precision" (how close are the readings to the average value of readings). I said that I don't care right now about the calibration scheme because i 'm not really interested if the temperature is 28.4 and I read in my measurement 29.4. I care if the temperature rises 0.1 C to be able to read it (so if i improve the precision of the readings then I will calibrate the sensor to get better accuracy). Sorry for my poor explanation and English.


texts: 120vac to 180vdc @ 300ma, non-isolated current-limited

texts:
What topology should I use if I'm wanting to obtain CC/CV -- 300ma / 180Vdc from a 120Vac input, where mains isolation isn't a concern?  My application will tolerate slight overcurrent (maybe to 600ma) at lower voltages (90vdc), and will tolerate slight overvoltage (to 200v) if the current tapers below 300ma once exceeding 180V.

I'm hoping it can be as simple as a ballasted voltage doubler or something along those lines.  The BOM for a single piece would ideally be below $20.  I do not care at all about efficiency, only low BOM cost and "relative" robustness.


texts:
I am trying to create a PWM signal using a POT from 555 Timer to control speed of a 5V DC motor. I have a development board with a C8051F020 microcontroller, a 100K POT and an LCD display. The requirement is to generate PWM signals externally so that the microcontroller is free to do other things that needs to be done for the project. I need to use the DAC from the microcontroller to drive the 555 Timer.

Scenario: The ADC on the micro reads the value from the POT (present on the Dev board). The DAC converts it to an analog value which can be used by the 555 Timer. I cannot directly connect the pot to the Timer.

My understanding is that the ADC and DAC do not have to be physically connected together on the board. Instead the digital values sampled from the ADC can be used by the DAC through software, am I right? So my question: is it possible to connect the DAC of the microcontroller to the input (pin 7) of a 555 Timer with a level converter from 3.3V (DAC) to 5V (Timer) in between?

EDIT 4th Feb 2014

I am using LM741 OPAMP as a comparator. The Timer is configured in an astable mode. For prototyping purpose, the DAC from the microcontroller is replaced with a 100K potentiometer. Since the DAC is supposed to be the reference voltage to the comparator, I found that the LED would always light up (although very dim) because of the capacitor C1 voltage goes from 1/3*Vcc to 2/3*Vcc which is why the LED was dim because the lowest voltage was 1/3*Vcc = 1/3*5 = 1.67V. So I switched the terminals for the comparator and now the reference voltage is C1 (capacitor voltage) as shown in the schematic below. My questions:
1) Is it alright to replace DAC with a potentiometer to represent DAC voltage as the voltage from the POT?
2). Is it wrong to switch the terminals around? I tested it with inverted terminals and the LED completely switched off and glows bright when the DAC voltage (POT) is turned high up. Also tested with the motor. When the DAC is the reference voltage (pin 3 of LM741) then the motor starts up slow and cannot be stopped although the POT is all the way down. And when connected as shown in the schematic, then the motor is stopped in the beginning.


texts: why Boost converter output voltage decreases at high power?

texts:
I am implementing non-isolated Boost Converter, capable of handling a power of 1Kw and output voltage is to be maintained at 400V at an input voltage of 120V . At smaller load current (around 2.5 Amp input, 0.8Amp output current) the output voltage across the capacitor stabilizes and it attains a stable value with a small ripple. But as I increase the load current (4.5 Amp input, 1.43Amp output current) the output voltage across the capacitor starts discharging fastly and never attains a stable voltage level. I am using two 3300uF capacitors rated at 350V each, connected in series at the output. I don't understand why the capacitor discharges as load current is increased?

the schematic for boost converter is attached here .


texts:
I am ordering the stencils and I do not know if I shuld order .12 o .1 ones. There are some TQFP64 ISs and 0603 passive elements. I'd like to avoid bridges.

Thank you
Peter


texts: In a simulator, outputing +/-5V peak AC through bridge rectifier then opamp buffer gives 5V DC output... software error or does this really happen?

texts:
In a circuit simulator I'm using it shows that if I run an AC voltage through a bridge rectifier and output that to a op amp buffer, the voltage at the input of the opamp (and hence the output) is the peak AC voltage I set on the source. Is this a software error or does this happen in real circuits? If so... why? If I understand correctly the AC source should always have a neutral terminal and the other terminal oscillates between +ve and -ve voltage...

Here is a permalink to the design in the circuit simulator if you want to check it out in action: it animates the voltage and current flow in real time. Circuit Simulator Permalink

Thank you in advance!


texts: Replacing incandescent bulbs with LEDs, unexpected behavior

texts:
I have an over-the-stove microwave/hood vent combo with 2 adjustable-brightness lights.  The lights appear to be 12V lamps with a G4-style connector, and they burn out too often. I decided to go with LED to reduce the maintenance.

I bought 12V LED lights with the G4 style base and replaced the bulbs.

They didn't work.  They turned on, but the brightness was nowhere near my expectations.  I tried reversing the polarity with no difference in result.

I figured that the power to the light sockets must be AC, or the LED's did not support different levels of voltages (I got them cheap from China).  So, credit card in hand, I went looking for LEDs that could handle AC and were dimmable.  I found some, ordered them, and received them.

I tested it out after I replaced the first bulb.  Eureka!  The bulb was bright, and dimmed properly.  All done.  So I replaced the second bulb.

All of a sudden, both bulbs no longer work: very dim, not dimming, just like my first LED experience.  I experimented:

1 LED installed, 1 incandescent: bright, dimmable light
2 LED lights installed: dim, barely visible
1 LED installed, other socket empty: dim, barely visible
2 incandescents installed: bright, dimmable

I'm trying to figure out how the sockets could be wired that would give me this result, and what I can do about it.


texts: Can a transformer run on low voltage ac?

texts: Can a 0.5 VAC power supply be stepped up to a higher voltage with a transformer?


texts: What is this connector name used on the NordicTrack RW200?

texts:
I need this exact connector, but I can't find it. It's used on the NordicTrack RW200. The female is about 8 x 10 x 20 millimetres.
I looked at : https://helpful.knobs-dials.com/index.php/Common_plugs_and_connectors


texts: Transfer function of two RC circuits connected together

texts:
I need to find the transfer function of two RC circuits connected together.

This is the schematic:

Here is how I tried solving it, using maple, the two equations for nodal tensions are found at (1) as the solve({eq1, eq2}) parameters:

eq1 is the sum of currents at node A, eq2 is the sum of currents at node B.

Well my problem is that I get a result at (3) that is not the answer from the solutions booklet (which is at (4)).

I am quite rusty into solving circuits, could anyone take the time to explain me how to get to the correct answer? I must find the transfer function \$ G(s) = Y_{2}(s)/U_{1}(s) \$. \$ u_{1}(t) \$ is a voltage excitation, and \$ u_{2}(t) \$ is the same voltage as \$ V_{C_{1}}(t) \$.

Thanks!

P.S. If anyone could tell me what I did wrong in nodal analysis it would be great.


texts: I have a range of heating elements with different power ratings (i.e. different resistances). Is there a way for my microcontroller to detect what power they are so I can use the microcontroller and a Triac to modulate the power to a specific power?


texts: How can I combine two different voltages & have it power on together with only one switch?

texts:
I don't know much about electricity, calling all experienced electricians out there!
My goal is to merge the max 6V small water pump to my air conditioner. I'm trying to connect a small submarine pump with my air standard 115V window conditioner. I need a solution on how to properly and safely get this to work.
Essentially I want to power on the air conditioner and also have the small water pump power on automatically. I don't want to damage anything or cause a fire, so please let me know what I can do to get this to work.
P.S. If there are important steps required, please list them in laymen's terms.
Thank you!
Below here are links to the small water pump and air conditioner:
https://www.ebay.com/itm/DC-3V-5V-6V-small-Micro-Submersible-Mini-Water-Pump-Fish-Tank-Fountain-Aquarium-/254406810014
https://www.bestbuy.com/site/ge-700-sq-ft-14000-btu-smart-window-air-conditioner-white/6390678.p?skuId=6390678


texts: Why don't *small* electric cars use small cheap hobby motors?

texts:
The automotive blogger Jason Torchinsky recently bought an inexpensive electric car, a Changli Nemeca, whose motor he describes as being powered by five car batteries and producing 1.1 horsepower (820 watts). He says it's like what you'd find in a washing machine, although it's DC not 120 V AC.  It's about as big as a 1 quart food container.  Online, similar motors cost about USD 100.
(Yes, this is much smaller than what's in a Tesla or Volt or Leaf.)
But motors of the same power (output watts, not "kV") for hobby radio-control cars and aircraft are about a quarter the cost, and a quarter the linear size (so 1/64th the volume and mass).
What theoretical or practical concerns stop such smaller cheaper motors from being used in larger applications like golf carts and household appliances?  Power is power;  something like a belt drive can trade off speed against torque.


texts:
I'm building a small server, and I was planning to add a smaller disk to perform backups. The problem, here, is that ideally the smaller disk should be turned on just when performing the backups and then shut down when the backup is completed.

Since the motherboard supports SATA hotplug, I was planning to just put some high power MOS (in fact they are more complex switches, but let us consider it just a PMOS) in series with both the 12V and the 5V rails going to that HDD. This way it should turn off.

Now, is there any problem with this approach? I mean, the data cable will be always attached, and I'm just removing the power. Can this cause problems?

The disk is a 3.5" HDD (7200rpm)


texts: I have an electrolyzer that works with car battery (12 volts DC) and draws current around 15 amps. I have a digital multimeter that can measure 10 amps at most. So how can I measure the current? Maybe I should use a resistance to measure its voltage but I can't think of a resistance that would tolerate 15 amps.


texts: Single board computer draws 0.22 amps: How to calculate how long a 2400 mAH 3s Lipo will provide power?

texts: I've got a Raspberry Pi 3 single board computer that I'd like use for remote data collection using lithium polymer (Lipo) batteries as the power source. When recording data, my multimeter shows that I am pulling about 0.220 amps. Battery is a 3s 2400 mAH Lipo. What is the calculation for determining how long this battery will power my set-up? Thanks in advance...


texts: How do I remove unnecessary fills in an EAGLE polygon?

texts: There are a lot of resistors and diodes on the board, where the polygon passes like this. How can I get rid of it?


texts: Problem feeding an ESP8266 and RGB 12V led strip from single source

texts:
I have an issue while was trying to feed an ESP8266 nodemcu v3 lolin and a RBG 12V led strip from the same source. When I try to use the same source, I am unable to access this ESP8266 webpage, as well as use the button to turn this strip on and off, but it shows that is receiving power as well as the RGB led strip. I am using a power supply of 12V 5A.
This is the schematic:

What I have done:

If I disconnect the 12V feed sent to that led strip, I am able to use that ESP8266 without problem.
If I feed that ESP8266 from my computer, without using Vin from the DC DC converter, and leave the rest of all the connections, I am able to use that ESP and control the led strip as expected.
If I feed that strip directly without using the DC DC converter input pins, and feed this ESP with USB, it works also has expected.

For a better understanding here it goes in pratice what I have:

Anyone knows what can be happening, and how to solve it?


texts: Can someone briefly explain what the use of this kit is?

texts: I have no idea what this kit would be used for. (Asking for a friend...)


texts:
I have to put a GPS antenna on a PCB layout, but not sure how to calculate a matching network, and how to check that it will work correctly.
I've chosen components with desired features (radiation diagram, amplification, and cost).
Actually, there are two or three networks, antenna - LNA - SAW - output.
But how do you choose the impedance matching components? For example antenna's and LNAs datasheets suggest different inductances. Do I have to put both inductances or choose one that fits?
SAW filter datasheet says that its input and output is 50 Ohm and nothing more. But here in this article Adding A GPS Chipset To Your Next Design Is Easy they use a capacitor after SAW.
This device in general is a small wearable GPS tracker - gsm+gps.
Components

Antenna

Amplifier

SAW filter

Is there some software for network calculation, or maybe some open-source ready schematics?


texts: For a Zener diode voltage regulator circuit: Why can't you place the resistor after the Zener diode?

texts:
This previous post is the closest thing to an answer I could find, but I don't quite understand why the load will still see the full voltage of the source and not the zener voltage. The contributor who answered stated that since the combination of zener and series resistor is in parallel with the load, the load will still see the full voltage of the source. What I'm having a hard time understanding is how the resistor placement affects the voltage seen by the load. Thank you in advance
EDIT: Here is the circuit in question (from the post I linked to)

EDIT 2: Okay, I'm slowly realizing my faults in asking a question without providing as much specific detail as possible. Here goes:
What I'm trying to do:
I have a bicycle hub dynamo that produces single phase AC voltage that can reach up to 60V peak (120V pk-pk) going about 55mph.
I'm trying to rectify and regulate the voltage down to 5V so I can charge a cellphone. For the most part I have the 5V regulation down (I'm using a DC-DC buck converter (TI's LM2596).
The issue I'm trying to resolve is during the rectification stage. I'm using a bridge rectifier and smoothing capacitor to rectify and smooth the voltage coming out of the dynamo. However, the smoothing capacitor I have is only rated at 35V so at those higher outputs of the dynamo (ie. above 35V peak), I'm assuming I would blow the smoothing capacitor up without a zener voltage regulator.
Here is a more accurate picture of my setup (I simulated the dynamo using a transformer at the input):

So in the picture, I have placed the series resistor correctly. My original question is: why can't I put the series resistor after the zener diode?
EDIT 3: For completeness here is the simulation for the incorrect schematic. The zener has 15V breakdown, but the output still sees the rectified ~30V of the source:


texts: Design of variable split rail power supply

texts:
I'm attempting to drive an array of piezo transducers and am struggling to find a good design capable of driving from around +-5V to +-30V at about 2A for my testing. There are about 12 sets of transducers that will need to operate independently and thus require their own driving circuitry. I am planning to use half H-bridges for this. Something like this image:

I've got access to a 0-30V, 10A supply, but most of the circuits I've come across for split rail designs are a bit underpowered and intended for fixed voltages such as this one:

I also looked at using something like an LM1370 (500kHz High Efficiency
6A Switching Regulator), but it seems as though it may underpowered too.

I apologise if this question is a bit open-ended, but if anyone has any advice on an reasonable solution for this, I'd be very grateful.

Thanks in advance for any help!


texts: How to power AC bike lights with batteries?

texts:
I have a more then decent set of lights on my bicycle link. They are currently powered by a dynohub in the front wheel of my bicycle. The dynohub has an output of 6V AC and the light has a AC/DC converter inside. I'm not looking to open up the casing and removing it!

Is it possible to power the lights with rechargeable batteries or 18650 accumulators that output DC? If so, how?

Thanks in advance!

UPDATE Thanks for all the replies!

I tried hooking up some batteries directly like your suggesting. They turned on, but the light of 2 AA batteries was still quite dim.

I got an old USB cable, cut one end off, put it in a small powerbank (1amp, 5v) and hooked those cables up to the light.

This gave me a better brightness, but after a few minutes the light turned off. The powerbank and lights are still working.

I'll contact the manufacturer for more info.


texts:
I am investigating using a triac instead of a relay to control 250V 10A devices.

However all the 600V 16A triacs come in TO-220 packages.

According to AS/NZS 3100 and AS/NZS 60335.1 I need at least 2mm creepage isolation between 250v circuits, but that is impossible with TO-220.

How do people build 10A circuits with these triacs?


texts: How is quality factor affected when combining inductors?

texts:
Lets say I have an inductor, L1 = 22 nH, with a quality factor (Q) of 50. I need an inductor of 44 nH, so I put two L1s in series. Will the Q of "the combined inductor" be 50?

What if I want half the inductance, and place two L1s in parallel?

Best regards
-paw


texts: If I have a regulated 5v supply how can I power a micro-usb b device?

texts:
Let's assume I have a good solid 5v supply and I want to power a device, like the Raspberry Pi, via a USB micro-b connector.

What is the easiest and/or best way to go about this? Can I just hook the power up to one of the USB pins on a breakout board or is there something more to it?


texts:
(Short disclaimer, I don't know much about electrical engineering other than what I have learned in physics in high school and the little I have learned from working with electrical engineers)

Is it common to have 2 amps running through a transistor (than can support it of course) or is there some sort of circuit design or something that would allow you to direct the current to where it needs to go and have a lesser current run through the transistor while still having the transistor in use?

I feel like 2 amps running through a single transistor is bad (idk if it is or not) so I just wanted to see if there was another way to do it... also save me money so I don't have to buy more expensive transistors


texts: Are FPGA Mezzanine Card (FMC) interfaces supposed to be compatible across different FPGA boards?

texts:
The FPGA Mezzanine Card is a connector intended for use with daughter boards that have high frequency components. Thus, if one was to use a 100MHz+ daughter board, it would require use of either FPGA Mezzanine Card interface or High Speed Mezzanine Card interface and using just normal pin headers would cause signal integrity issues as far as I am aware.

The FPGA Mezzanine Card is used in different FPGA boards that have FPGAs from different manufacturers. Are Input, Output and power pins supposed to be in the same places such that we can take a daughter board to be used with Intel FPGA board onto a Microsemi FPGA board without trouble? In order to do this, the FPGA Mezzanine Card pinout must have single ended, differential and power supply pins at the same locations.


texts: Beaglebone Black - Maximum current supplied by 1.8V analog rail (Pin P9_32)?

texts:
On the Beaglebone Black, what is the most current that the 1.8V analog rail (pin 32 on header P9) can supply?

I can't find it in the System Reference Manual. I would've expected to find it in section 6.1.9, "Power Rails".

I want to use it with a voltage divider to get a 0.9V source. I plan to use it like this:

With two 10k resistors and the op-amp buffer, the current should be 90 uA -- very small.


texts: How would I get a full range voltage reading from a pressure sensor?

texts:
I am making an application using the DIY Force Sensitive Resistor (FSR) taken from this instructable. The resistance of this sensor typycally ranges from 20kOhm when at rest to 9kOhm when pressed.

How would I convert these resistance values to a signal where 0v corresponds to the rest condition and 5v corresponds to the "pressed" condition so that I can read it with an Arduino?


texts: Peak detector is not working when voltage is changed

texts:
I am trying to design a peak detector in Multisim simulation tool. I have designed buffered peak detector to get peak voltage of sine signal. The designed circuit is working when signal voltage is constant, for example when signal voltage changes from 1V to 0.5V then it is giving 2V as peak detector output. The designed circuit as shown below.

In the above circuit I am using switch to change the voltage of sine wave from 1V to 0.5V. I am using one more switch to clip negative cycle of sine wave, then i am using buffered peak detector to get maximum voltage.

When i apply 1V sine wave it is working perfectly and giving peak voltage as DC. The problem is when I change signal voltage from 1V to 0.5V then also it is giving 1V as peak. ANy one suggest me what mistake i am doing. I want to design peak detector that will give max voltage even there is voltage variations.
I am trying to attach Multisim file but it is not possible for me. I don't know how to attach file so i have added image.


texts: Can I use a Dupont cable with a resistor soldered in the middle as a pullup resistor for I2C comms?

texts:
The short question: is there a difference between using (on a breadboard) a standard through-hole 10K pullup resistor, versus using a modded Dupont cable with a 10K pullup resistor soldered in the middle, when setting up an MCU and a peripheral using I2C? The modded Dupont cable does not work for my case.

Environment: breadboard, the Espressif ESP32 MCU as I2C Master using pin #21 as SCL and pin #17 as SDA (the internal "weak" +-4.7K pullups are enabled), a Melexis MLX90393 magnetic field sensor as I2C Slave on a Sparkfun breakout board (product https://www.sparkfun.com/products/14571; the 10K pullups on the Sparkfun breakout board are also enabled). See picture for the breadboard setup (focus on the pullup resistor).

The software works fine and I get 5 sensor readings per second if I wire a bare-bone 10K pullup resistor between the hole next to the MCU's SCL pin #21, and a hole on the 3.3V rail of the breadboard. This is standard procedure for I2C schemes in order to pull the I2C SCL high by default. Same for SDA.

However, I wanted to make wiring up things on the breadboard much easier and use a modded Dupont cable for the pullup. So I took a 30 centimeter Dupont wire, cut it in the middle, and soldered a standard 10K pullup resistor in between and put a shrink tube around it. If I measure the impedance between the 2 ends of the cable then it is +-10K Ohm.

So I plugged the modded Dupont cable besides the MCU's SCL pin #21 and the 3.3V rail of the breadboard (replacing the bare-bone resistor's of the previous configuration). Now the system does not work anymore* (the I2C communication fails).

What could be the (electrical?) reason for the failure? I do not have an oscilloscope but I do have a logic analyzer.

Thanks from a beginner.


texts:
I've been trying to get 2 input push-buttons working on my MSP430 FF529.

I've been successful with 1, but not the other, which leads me to think the one not working is broken, since I'm doing the exact same thing for both.

The two push-buttons on this board are attached to ports P1.1 and P2.1

I got P2.1 to work fine by doing:

P2DIR = 0x00;    //set as input
P2REN |= 0x02;   //enable pullup for p2.1

Now for Port 1, I also need an LED attached to P1.0 as output, so I have done:

P1DIR = 0x01;  //set p1.0 as output, and p1.1 as input
P1REN |= 0x02; //enable pullup for p1.1

So P2.1 is working perfectly fine.  The default value is HIGH, and I can see it switch to LOW when I press the button.  But this is not the case for P1.1.  The default value for this is LOW, and pressing the button has no effect.  Am I missing something obvious? Or something different about this port than the other port?

The parts I'm referring to are in green boxes.

MSP430 FF529


texts: Why does an op amp need to be powered before applying the input signal?

texts: I was taught that a power supply needs to be applied to an op amp before an input signal. I understand that doing that in the wrong order fries the chip, but why?


texts: How to wire this relay with a H/L (High/Low) jumper to Raspberry Pi?

texts:
I got this relay to make an IoT lamp but I can't decipher the labelling on it. There is no labelled GND, VCC, or JD-VDD just 'L' and 'H'. I wired 'IN' to an I/O pin, GND to GND, and the jumpered pin to the right to 5V (assuming it was VCC) and running the script still did not activate the relay.
Am I missing something? This relay looks a little different than the ones in other tutorials..


texts: How do I calculation to see if Thyristor complies with DO-160G indirect lightning protection

texts:
I have been working with TVS diode and found that the capacitance of tvs diode is large; therefore, I will not be able to use tvs diode.

Thyristor, on the other hand, has low capacitance for high speed ethernet data. Unlike tvs diode which displays Power peak vs time chart (I could calculate using the chart), how do I calculate  for thyristor amperage at different waveform?


texts: What is the purpose of the thin wire at the top of power transmission lines?

texts: I know a power transmission line carries usually two sets of 3 phase conductors. But I have noticed a relatively thin wire at the center-top of the power transmission line. What is the purpose of this thin wire?


texts: Power line protection: overvoltage, ESD, voltage polarity

texts:
We are designing an industrial control board. The input voltage of the board is +12V, ground and -12V. Our previous design does not include any power protection and now I want to add over voltage and ESD protection, as well as voltage polarity protection.

Previous design

New design

Schottky diodes are added to prevent reverse voltage. Zener diodes are to prevent ESD, voltage transients and over voltages.

My questions

Could I have comments on the design?
Can this set up secure the system from all kinds of wrong voltage inputs?
What shall be the clamping voltage of the zener diode? Shall it be around +15V?


texts: What causes the necessity for a bias resistor for floating differential mode inputs?

texts:
Following excerpt from a text says Figure a and Figure b are equivalent:

But in practice when Figure b is used we are recommended to use a 10k or upto 100k resistor between the inverting terminal and the amplifier ground. Otherwise saturation is observed.

In practice Vin can be a battery or a transducer which is powered by a galvanically isolated power supply.

Regarding Figure b why does this issue happen in practice even though Vin is floating? Why such resistor necessary?


texts: Smartphone internal charging circuit type and efficiency

texts:
USB usually provides 5V (or even more, for example 9V with Qualcomm Quickcharge) and the phones contain a single li-ion cell with 3.5-4.3V, so there must be some dc-dc converter in between.

I wonder if it is typically a switching regulator and what efficency they provide in the smartphone environment?
After all, how much energy input is needed for a given nominal battery capacity?

I could not find concrete numbers on this, the more detailed power bank calculations only go to the 5V output and then assume the same current at the phone battery, like a simple linear regulator. Which seems to be pretty close in practice? Has nobody done any real mesurments so far?

Hints to battery managment IC datasheets from common smartphones are also appreciated.


texts:
we got this ripple filter circuit as shown in this figure.Input voltage

$$ V=v(1+\cos (\omega t)) $$

is fed to left input and then find output voltage. Now this problem confuses me. For instance I cannot figure out if they are parallel or series? And therefore I could not found impedance to find the output voltage. How do I proceeded in this problem?


texts: Problems driving pulse transformer with low-side MOSFET switch

texts:
I'm trying to produce a DC isolated output voltage of approximately 2.5V at 100mA from a ~55V DC supply.  The purpose is to charge individual cells in a lead-acid battery from the power of the battery as a whole (it's a 48V system, 2V cells).

I've been playing with a PoE pulse transformer (Coilcraft POE13F-25LB).
The idea is to control pulses in the primary via PWM.

I'm switching one side of the primary to GND via an N-channel MOSFTET (Fairchild FQP45N15V2) which is driven by a MOSFET driver (Microchip MCP1415).

I'm switching at 250KHz to match the design frequency of the transformer.

I'm not sure this is the correct way to drive the pulse transformer.  Here's a scope grab showing the pulse from the driver and the voltage on the MOSFET side of the transformer.
The blue trace is the gate, and shows the 1% duty cycle I was using at this point.  The yellow trace shows the voltage drop when the MOSFET turns on, and then when it closes the voltage climbs again and oscillates.
This second grab shows the same situation at a 40% duty cycle:

It's this oscillation when the MOSFET turns off that's causing problems.  Do I need to do something else to drive the transformer?


texts: Components with multiple possible values - how to designate on schematic?

texts:
Quite often it happens to me that values of resistors or capacitors don't play such a significant role. This is mainly the case with decoupling capacitors and e.g. LED series resistors. Often in decoupling caps their ESR and other characteristics are more important and I usually specify them globally as X7R/X5R. If I were designing more analog, this would not be as applicable, as in analog, component values/properties are much more strictly defined.

I, as a circuit designer, presumably have to be specific about the whole project so that the other people can take it and produce a working board. But this means that I put constrains on the purchasing department. If for some reason 4-resistor arrays of \$100\Omega\$ were not available, that could result in a delay, when the purchasing person reaches back to me with the issue.

Wouldn't it be fun, if the schematic defined more possible values for that component? For example it could say, that 80, 100, 120, 180 Ohms are all OK. Or simply define a range 80-180 Ohms.

But how to mark it on paper? Or more generally, is it worth it?

simulate this circuit – Schematic created using CircuitLab


texts:
I purchased a SD-based 4-channel mobile DVR on eBay that did not include the connector one would use to connect reverse lights, turn signals, and other inputs so the DVR can return a relevant camera view to an on-board monitor.

It is similar to a motherboard power connector, but the sockets are smaller and there are 16 pins instead of 20-24.  I had a similar unit where I was able to find a 14-pin PSU connector that got the job done, but even those sockets are too big.


texts: Power capacitor needed with high current LED

texts:
I'm designing a pcb which, among other things, with control several high current LED panels. These panels have the proper circuitry in them, so all I do, is give them 12v.

The maximum current one will draw, is 30A. I'm using a thick PCB with bus-bars. I am controlling the panels with a low side power mosfet. I am using a microcontroller for the logic, on the same power supply, dropped down to 5v.

My question is, do these panels need a power capacitor to avoid having the power rail saturated and reseting my mcu when they are immediately turned on? If so, is there a ballpark of what sizes should be used?

I have done pcb's with stepper motors and servos, and without a cap for each, they would reset the mcu. I used around a 470uF cap and it worked. I couldn't find anything online about the characteristics of LEDs and if they need caps like servos and the like.

Thanks


texts:
I am studying Digital Logic Circuit right now and I have question to ask. I have searched lot of places in order to find this answer, however due to my lack of searching ability I was not able to find any. So, I came here to ask this question here.
My question is that "Will SR Flip-flop made with NOR gates and NAND gates return the same results?"
I do know that if we make SR Latches with NOR gates (let's say that this latch is called A) and if we make SR Latches with NAND gates (let's say that this latch is called B), the result of A and B are quite different. As it is mentioned here: SR Flip-Flop: NOR or NAND?. Also I do get that the diagram notation between both A and B latches are quite different in circuit diagrams. (I do know the main difference between latches and Flip-flops)
However, I cannot find information about SR Flip-flop with the same question. Both NOR and NAND implementations are noted same in circuit diagrams.  (Searched Different implementations of JK flip flop here, but the answer made me quite confusing. Since the answer says that the circuit truth table is wrong.).
Since my major is CSE rather than electronics engineering, I do not know how to treat recursive circuits in Flip-flops and Latches. Meaning that I am unable to draw truth table and characteristic table myself.
So, I would like to ask,  "Will SR Flip-flop made with NOR gates and NAND gates return the same results?" and also in a similar manner, "Will JK Flip-flop made with NOR gates and NAND gates also return the same results?" (Since I was not able to find JK FF as well)
Since I am new here, if there are any wrong expressions please let me know. I will edit them as soon as possible.
Thanks.


texts:
I have been designing a PCB which includes an SD card connector. As I'm not a PCB designer expert, I was looking for a reference design when I came across with the circuit bellow, extracted from Texas Instruments

My question is about the purpose of the capacitor (C206, 0.1uF) tied between GND and MicroSD_earth (Chassis Ground). Other reference designs seldom includes that capacitor, and usually the chassis ground pins are tied directly to GND of the PCB or left floating. Whats the correct way to go and why? I'm really confused.

Hypothesis:

1) Tie SD connector metallic shield pins directly to the ground (PCB GND);

2) Tie them to the ground with a capacitor, like depicted in the figure shown above;

3) Left shielding pins floating.


texts:
I am looking to design a boost convertor for a high school project and after doing quite some research I have come up with the following design.

I am looking to double my voltage. (Input voltage will most probably be 9 volts)

The left part of the circuit is an astable multivibrator and the right part being the main circuit of the boost converter. I just wanted to know whether my circuit will actually work and the astable multivibrator will be successful in providing a switching frequency to short the circuit. I am no expert in electronics and could do with some help. Please mention the necessary changes I need to make if my circuit is glaringly wrong.


texts: Designing with AC'97 - why does it not have a (FIFO) buffer?

texts: The AC'97 codec seems to dominate the world of digital audio I/O but, what is weird is that it has neither interrupts nor buffers so that it is difficult to interface with a controller, which has other activities. The AC97 demands polling it periodically (44k times per second), checking for the time to communicate a next sample. This is not the usual way of communicating usually. Usually, CPU fills a buffer and is notified when the operation is complete or waits explicitly for the result if it has nothing else to do. Such "batch processing" is more efficient because, at first, sending bursts is more efficient that doing one item a time and, secondly, it reduces context switching n times, which also optimizes the computational resources accordingly. But, you need a FIFO for that. What is good in this, on sample at time, terrible design of AC97 and why does nobody care? I see that Xilinx fixes it with ML507 demo board (I see FIFOs in AC97 controller introduced there) but I have Digilent's V5 Genesys board whose controller does not provide any FIFO. So that Microblaze must communicate one sample every 1/44100 of a second. Is it efficient? How are you supposed to control it?


texts: Power supply Harmonics calculation using FFT

texts:
I am trying to calculate harmonics of power supply with using a FFT. My sampling rate is 400 samples/sec. This means 8 samples per cycle. I am not getting sensible answers and think that I am making a mistake as I am getting harmonics power more than my signal power.

The input of my FFT is

0
222
325
222
0
-222
-325
-222

at 2.5 ms spacing. The output of my FFT is:

0 Hz: 0 + 0j
50 Hz: 39.59798 - 1317.508801j
100 Hz: 0 + 0j
150 Hz: 39.59798 - 17.508801j
200 Hz: 0 + 0j
250 Hz: 39.59798 - 17.508801j
300 Hz: 0 + 0j
350 Hz: 39.59798 - 1317.508801j


texts: How to measure current without shorting/how to limit current?

texts:
Follow up of this question I asked. My DAQ can sink a maximum of 4mA. The instrument it is hooked up to doesn't have a data sheet or anything that tells me how much current the pins supply. How can I measure this without shorting?

Knowing that the pin has 5V, can I simply put a resistor in series from the pin to my DAQ's digital input pin to limit the current?


texts:
I should preface this by saying I'm a novice at all of this: I'm designing a system (using a stand-alone FPGA board combined with an ADC that offloads data to a GPU) that is supposed to look for high Q signals embedded in white noise. Currently, I'm at the very beginning of the testing stage, and I have a few fundamental questions about what I'm seeing at the output.
As a test of the system, I've injected a -27 dBm (~30mVpp), 420 MHz sine wave from a signal generator into the system. The signal is digitized by a 2 GS/s, 8-bit ADC (externally clocked) with a 20 dB front-end amplifier. I take 226 samples, do a DFT (of the same length), and compute the power spectrum. Below is the output. Note, that I have applied a Kaiser window to the data before taking the DFT.

There is an obvious peak at 420 MHz (along with a few spurs), but the amplitude is way down from expected (-7 dBm). Things start to look even stranger as I zoom in. Taking a 4 MHz span around the central peak produces the following:

This looks nothing like the nice smooth peak I expected. And zooming in even further makes this point clearer:

My questions are both fundamental:

I think I am seeing significant amounts of both phase noise and scalloping loss. Are these the right words or is it something else?
My peak is incredibly broad. I have checked on a commercial spectrum analyzer (with poorer resolution but over the same span) and do not find that the peak is anywhere near this broad. Could phase noise be causing this?

Big thanks for any insight you may have.
Edit
In response to a question about repeating taking data with a lower order Kaiser, I've done just that and attached the plot below. In this example, the window is still a Kaiser but with α = 1 (it was 14 before). The top subplot shows the span from 418-422 MHz. The bottom subplot is a zoom in from 419.5-420.5MHz. Looks like the scalloping is greatly diminished. That gives me a rabbit hole to jump down.

End of edit


texts: Do electrons go towards higher voltage or lower voltage?

texts:
Can someone clear this up for me once and for all? I feel like Thomas Edison really screwed me when he made everyone believe that current is movement of positive charges.
Do electrons go from high voltage to low voltage or from low voltage to high voltage?


texts:
Voltage gain of an amplifier is defined as

"magnitude of output voltage / magnitude of input voltage"

OR

"Vout(r.m.s)/Vin(r.m.s)"

OR

"change in output voltage/change in input voltage"

In the figure given below they say that the by using bypass capacitor C2 which is by passing R(E) increases the gain because now the input signal by passes R(E) and so the signal faces less resistance than if R(E) is not by passed.

But what i am not understanding is that when by pass capacitor is used then magnitude of the input signal is increased but at the same time magnitude of the out put signal will also increase.

And

If magnitude of input signal decreases then the magnitude of out put signal also decreases and as gain is the ratio of output to input signal so the gain will not remain constant whether R(E) is by passed or not ? as both output voltage and input voltage are increasing and decreasing simultaneously then how the voltage gain is increased by bypassing the R(E) ?


texts: Exam question: measure amplifier \$h_{oe}\$ using a signal generator and oscilloscope

texts:
I'm running through some old exam papers at the moment and one of the questions are:

The parameter \$h_{oe}\$ is needed to calculate the output impedance of an amplifier. Explain in detail how to measure the parameter \$h_{oe}\$ practically in totality from start to end by using a signal generator and oscilloscope.

I've founf a couple of examples showing how to meazure the output impedance of an amplifier using a signal generator and an osciloscope with a variable resistor such as this example at learnabout-electronics.

In my book they go through an equation where you can get \$h_{oe}=\frac{Z_oR_3}{R_3-Z_o}\$ (This is from a Bootstrapped common emitter ammplifier circuit.) So would you go through the process to find the output impedance abnd then plug the values into the equation above and calculate \$h_{oe}\$?

Update
\$Z_o\$ is the output impedance and \$R_3\$ is the resister between the \$Ecc\$ and the collector which is dynamically in parrallel with the \$R_L\$.


texts: Is either of the following circuits usable as a minimalist UPS?

texts:
I have been working on a NAS server, which I want to run on a Raspberry Pi 4, but I already got the SD card corrupted once by interrupting power to it when it wasn't shut down properly. I then thought that the same thing could happen in the case of a power outage so naturally I decided to make a UPS for it.
I have looked at several designs on the internet but they all seemed way too complicated for my purpose, so I started thinking how a minimalist UPS could be made and came up with two solutions.
Given, however, that I am only a hobbyist I thought it would be wise to ask someone with a deeper understandin of electronics about whether any of these circuits would function before even trying to build one of them. So here I am writing this post.

In this first one I want to use a two relay relay board (such as this) as a DPDT switch to switch between the power supply and the battery. The idea here is that when the power supply goes out it unpowers the coils in the relays and thus switches them to their NC state, where the battery is connected (the power supply is connected to the NO terminals.)
The capacitor is there to supply the Pi with power until the switching happens (I don't know how many miliseconds it takes so I went with a 1F cap, the largest one I currently have at hand.) This is intended to work with a li-ion cell, thus a step up converter (set to 5V) is used. I would probably add a fuse (5-7A) to the battery too, just in case something went wrong.
The battery charger is meant to be turned on manually, though I might decide to automate it later with the help of an Arduino, which would monitor the battery voltage, too.
Here my question is whether this would work in practice as well as it does in theory or not? Also is there need for a diode anywhere? Could the capacitor cause some nasty backfeeding issues when the supplies are switched?

Here the idea is that the power supply is set to the float voltage of the used lead-acid battery and a step-down converter brings its voltage down to 5V for the Pi. If the power is disconnected the battery should in theory just take its place. If I decided to use this one I would probably add an Arduino here too to monitor the battery voltage. Would this work in practice?
In fact would either of these two circuits work in practice? And if they did are they a good solution or should I be looking for a different, more complex one?


texts: Calculating the square root of 8-bit binary number

texts:
I was looking for a way to calculate the square root of a given 8-bit number using only digital combination or sequential logic. Is that possible?

One way may be to just use a look up table since I'm not considering fractional parts at all (so \$ \sqrt{10} \simeq 3\$) but there has to be a better way than this. Can someone point me to that?


texts: How does current flow in the short circuit? Aren't the two ends at the same potential?

texts:
How does the current  flow in the short circuit wire ?
Isn't potential difference necessary for existence of current?


texts:
I am using the as6c62256 ic sram, this is the datasheet: datasheet
I am trying to write 1000 words of 8 bit, and then read them from the sram
is it possible to connect a binary counter to the adress pins of this ic to read and write data?
Write mode: counter begin from 0, for every adress write a word, increment counter and the next word and so on, etc...
Reset counter to 0 to Begin Reading
Read mode: increment counter, read data the corresponding Word
Help is appreciated, thanks to all of you


texts:
I am facing the problem with the heat of transistor disturb sensor reading. Here the link refer problem
I am using BC548 transistor. It is a bit hot when operating because it disipates power around 400mW. Its temparature is around 50 degree celcius. It is inside a case with the rest of my circuit. So I want to reduce the heat of transistor.

My question is...

Is it going to help to reduce transistor heat if I install transistor with a heatsink? I am not sure because BC847 seems not to have thermal pad.
If install a heatsink helps, Is it still reduce the heat if I place the heatsink inside my case and near a tiny hole there.


texts: How to protect an op-amp against high inrush current following a high input voltage pulse?

texts:
I have a circuit where I'm amplifying the output of a piezo transducer with an op-amp. By taking some readings, i've found that the piezo can output fairly high voltages when struck hard (~20V), and so I want to protect the op-amp against high currents.

To that end I thought about including a resister in series with the op-amp's non-inverting input, but I'm unsure on a few things. Namely, my questions are:

What value to use for resistor (R1 below), and how to calculate it?
How much current will be flowing through the op-amp due to the high voltage spike?
What's the maximum current the op-amp can handle on the non-inverting input?

Below I've drawn up a simple schematic to represent my circuit - I've used a 1Ω resitor to represent the load, but in actuality the output signal will be fed into an op-amp comparator and then into a microcontroller subsequently:

simulate this circuit – Schematic created using CircuitLab

Thanks for your help!


texts: Communication between laptop and atmega2560 via two Xbee S2C

texts:
I want to send data to atmega 2560 from my laptop using two Xbee S2C.

The first Xbee , let's label it A , is to be interfaced with the laptop.
The second Xbee , let's label it B , is to be interfaced with the atmega 2560.

I want to know how to configure these Xbees to communicate with each other.
I am a beginner , I know only few things :

The Xbee A will be interfaced with the laptop using Xbee usb adapter , which will facilitate the UART communication between Laptop and Xbee A.
The Xbee B will be interfaced with the Atmega2560 by providing Xbee B with power and connecting Tx and Rx of the micro controller to that of Xbee B.These two will then communicate via UART.

I am also not clear that the controller's Tx and Rx pin will connect to Xbee B's Tx and Rx pin respectively or the other way around. Please guide.

Here's the code I am burning to Atmega 2560 , initially for turning a led on/off on PB6

#define F_CPU 14745600
#include<avr/io.h>
#include<avr/interrupt.h>
#include<util/delay.h>

unsigned char data; //to store received data from UDR1

//Function to initialize ports
void port_init()
{
DDRB = 0x40;

}

//Function To Initialize UART0
// desired baud rate:9600
// actual baud rate:9600 (error 0.0%)
// char size: 8 bit
// parity: Disabled
void uart0_init(void)
{
UCSR0B = 0x00; //disable while setting baud rate
UCSR0A = 0x00;
UCSR0C = 0x06;
// UBRR0L = 0x47; //11059200 Hz
UBRR0L = 0x5F; // 14745600 Hzset baud rate lo
UBRR0H = 0x00; //set baud rate hi
UCSR0B = 0x98;
}

ISR(_VECTOR(26))        // ISR for receive complete interrupt
{
data = UDR0;                //making copy of data from UDR0 in 'data'  variable

UDR0 = data;                //echo data back to PC

if(data == 0x37)
    PORTB = 0x00;
if(data == 0x39)
    PORTB = 0x40;

}

//Function To Initialize all The Devices
void init_devices()
{
cli(); //Clears the global interrupts
port_init();  //Initializes all the ports
uart0_init(); //Initailize UART0 for serial communiaction
sei();   //Enables the global interrupts
}

 //Main Function
 int main(void)
 {
 init_devices();
 while(1);
 }


texts: Can I replace this filtering network with a saw filter chip?

texts:
The above image is the Application Circuit from the A7105 radio transciever chip's data sheet.

I think I am beginning to understand the purpose of most of these components.

I suspect that the circled components are working as a band-pass filter (or at least, a high-pass filter) for the module's frequency, which is 2.4 ghz.

I have not yet tried to build this circuit, as it is rather complicated and requires a lot of tiny smd components (on a custom board). So far I have only worked with already made modules which use this chip.

My question is:

If I replace the circled components with a SMD "Saw Filter" component, as a band-pass filter for the 2.4 ghz ISM band, is it likely to work? Assume that I also provide a suitable antenna, either a chip or pcb antenna.


texts: Series to Parallel inductance conversion

texts:
Reviewing some material I thought I understood, but it turns out there's some subtlety I'm not getting.  The usual formula for calculating the Q of a non-ideal inductor is \$\frac{Xs}{Rs}\$, where Xs is the series reactance and Rs is the series resistance.  For a parallel circuit, it's the inverse,  \$\frac{Rp}{Xp}\$.  The two are related by the equation \$Rp = (Q^2 +1)Rs\$, where Q is the unloaded Q of the element.  Consider a non ideal parallel LC circuit.  You have an R and L in series, and this series combination is itself in parallel with a capacitor.  Using the above transformations, one can convert the series resistance into a value of parallel resistance, and then using the value of parallel resistance solve for a value of parallel inductance using the second formula above.

But then, what is the resonant frequency of the tuned circuit? Is it given by the original value of series inductance, or the new value of parallel inductance?  The texts I've read make the assumption that the reactance of the parallel inductance is the same as the series inductance, and working out the equations with the Laplace transform of the original circuit shows that the resonant frequency is solely determined by the value of the original capacitance and non-lossy inductance.  Indeed, it would hardly make sense to try to calculate a new resonant frequency based on this equivalent parallel inductance value, because the transformation is only valid at one frequency! So what's the significance of this new value of parallel inductance, then?  For low Qs it can be significantly larger than the original series value.  Does any of this make sense?


texts: Two signals alternately on the left and right of a frequency

texts:
I was listening to the WebSDR of Twente University, just outside the amateur band, and saw these signals. The x axis is frequency in kilohertz, the y axis is time, where the whole axis shown is about 15s.

It occurred to me that the two signals are alternately left and right of the line on 13,971kHz. Would that be a coincidence, or is this some kind of transmission technique? If the latter, how is it called and how does it work?

The line seems to be unrelated, it's still there although the signals are gone.


texts: Rogowski coil output resistance series or parallel

texts: Rogowski coil CWTUM03 (30 MHz) gives a 50 ohm resistance when I measured between its center pin and outer surface of BNC connector. When I measure any signal through a coax with 50 ohm selected on scope as input resistance, signal is attenuated to 50% which could only mean that there is a series resistance in rogowski probe as well. I could understand the parallel 50 ohm resistance at the output of rogowski before coax cable as a seperate terimation irrespective of what coax user connect, but why the series resistance??


texts: Are consumer systems able to measure nanosecond timings?

texts:
Following the theft of my brother's car (a modern Audi Q-something), I got interested in how contemporary cars are protected.

The authentication of the key to the car is dreadful (I work in information security and how certificates are handled is painful to read) but even if that part was done right, an amplification attack would be possible.

The idea is that someone triggers on the car a request for the key presence (by pulling the handle for instance) and that request is amplified so that it reaches the key which is in the nearby house. That way the car is tricked into believing that the key is close and the doors / ignition are unlocked).

The paper Are We Really Close? Verifying Proximity in Wireless Systems from 2016 explains the attack quite well. The basic approach to protection is to measure the time the signal traveled to compute the real distance.

Let's say that the appropriate range for a key to be "close" to the car is 0 to 1 meter. 2 meters and above is "away". This means that the electronics of the car needs to distinguish a round trip for a key close to the the car of

$$t_{close}=2 \times \frac{1}{3 \times 10^{8}} \approx 6 \text{ns}$$

from a "far away" one

$$t_{away}=2 \times \frac{2}{3 \times 10^{8}} \approx 12 \text{ns}$$

This is about 5 to 10 nanoseconds of difference minimum.

Is this a realistic timing for consumer devices? (consumer in the sense that they are mass produced in cars and need to be accurate within this timeframe)

The calculation is done in the car, so miniaturization and power does not matter.


texts:
I have problem with upload program Flash for my AT33UC3A3256 Atmel. that what comes up when im trying to read JTAG ID:

Unable to enter programming mode. The read device ID does not match
the selected device or any other supported devices.
Please verify device selection, interface settings, target power and
connections to the target device. Timestamp:  2021-01-25 13:16:57.523
Severity:     ERROR ComponentId:  20100 StatusCode:   131101 ModuleName:  TCF
(TCF command: Device:startSession failed.)
Unexpected JTAG ID 0x0ffffffe (expected 0x0202603f).

The JTAG pinout is 100% correct. I am using JTAGICE mkII. in .adtf file for my processor i have same
expected ID like this above:
 <property-group name="SIGNATURES">
          <property name="JTAGID" value="0x202603f"/>
        </property-group>

Somebody know what is happening?


texts: I'd like to make a GPS logger. I've got a GPS from Microsoft Streets and Trips. I read that it communicates at 4800 baud over RS232 at 3.3 or 5v. I've got an MSP430G2231 from the launchpad kit and I'm a bit fuzzy on how to talk RS232 to this thing. I also want to write to an SD card, preferably to a file so I can pull the data off with a computer. The raw NMEA strings are fine,  I can parse those on the computer. The more detail the better. Thanks.


texts:
does anyone know of a product that can be used for waterproofing electronics and exposed wireing that is suitable for submersion for potentially long periods?

More specifically I am looking for a way to coat either thermocouples or thermistors that may be mounted on small PC.boards or sometimes just soldered to the end of connecting wires.
 I need the said devises to measure water temperature with fairly fast response time but not be affected by the conductivity of the water.


texts: Switcher discontinuous mode - potential EMI problem

texts:
I need to design switching mode power supply with input voltage range of 25V-45V and output voltage 5V@2A.

Power supply must be ON while the system is in sleep mode(~1mA consumption). In that particular case switcher will be highly inefficient and will be working in dicontinuous mode. Since I need to pass both FCC and CE will that be a potential unresolvable problem? I have previous experience in designing BUCK converter but none of them had to go through certification.


texts:
I am working on designing a reaction wheel using a BLDC motor.
Ho w can I calculate the terminal inductance (in H) for a brushless DC motor with the following properties:
Brand name: Racerstar
Item name: AirA 2508 brushless motor
KV: 1200KV
Thread: CW
Configuration: 12N14P
Internal resistance: 72mΩ
Shaft diameter: 4mm
Motor dimensions: φ31.5*35mm
AWG: 20#200mm
Cable length: 200mm
Weight(Incl. cables): 50g
Weight(Excl. cables): 46g
No. of cell(Lipo): 4-6S
Idle current@10V(A): 0.9A
Max continuous power(W)180S: 802W
Max continuous current(A)180S: 34.7A


texts: Slayer Exciter Interfering With Voltage Measuremnet With Multimeter

texts:
I've built myself a slayer exciter and I am trying to measure the output voltage. I've created a coil with approximately 10 turns and soldered a bridge rectifier to the ends of the coil so I can measure DC. However, as I turn on the slayer exciter circuit, it messes around with the multimeter and reads the voltage as infinite. I've mitigated this problem a little bit by placing the multimeter out of the coil's "sight". However, the readings are still slightly bogus (maybe 1-3 volts).

How can I resolve this problem further?

Any help is appreciated.

Edit: I've come to the conclusion that this is a radiation problem and am looking for some ways to improve my situation. I've been informed about the option to buy a better multimeter, so any other fix would be nice.


texts: Can I use resistors/capacitors to delay when a circuit turns on?

texts: I switched some electronic candles to be powered by a power adapter instead of batteries but when I power them up I noticed they all now "flicker" (which is a feature) at the same rate probably because they all use the same circuit. With batteries this isn't a problem because you'd turn them on/off at different times but now they all turn on at the exact same time when I plug it in. Is there a cheap way to delay these at different rates, possible with simple passive components?


texts: Drain current of NMOS circuit is constantly changing on DMM

texts:
Hello I am working on a lab that pertains to the IV characteristics of n type MOSFETS.The lab calls for recording the value of the drain current while increasing VDS/VGS from 0 to 6 volts in steps of 1 volt.

I constructed this circuit

As I increase the voltage for VDS/VGS I am experience I weird issue with the Drain Current readings. It issue is that it is not very stable at all. The current is constantly changing. I took a video of it.

https://youtu.be/-LMfpRZQWVA

is there anything I can do with the circuit to fix this?


texts: Chip antenna PCB layouts and matching network

texts:
I am designing a PCB layout for NXP JN516x Wireless Microcontroller (http://www.nxp.com/docs/en/data-sheet/JN516X.pdf). Part of the design is the antenna, where I have to choose a 50ohm antenna. I decided to go with a chip antenna (https://www.digikey.com/product-detail/en/ethertronics-inc/1001312/939-1040-1-ND/4754415), since it has a small footprint. According to the NXP JN516X datasheet, There is a matching network for the antenna, as shown in the figure below (Page 89):

But I can see from the datasheet of the antenna itself, there is a recommended PCB Layout, where it is clear in the below figure that there is only two matching components, and the datasheet didn't even mention anything about the values or whether they are inductors or capacitors.

I don't have much experience with antenna design.
Which matching network should I use, the one in NXP datasheet or the one in the antenna datasheet?

Update:
I found the below statement on page 27 of the chip datasheet, it said that we need the three external components L1, L2 and C1, as they form a 50ohm resistive network. Does that mean I don't have to remove L1?

Thanks in advance.

What should I follow


texts: Basic Question on Finding Poles and Zeros

texts:
What are the zeros and poles of the following? They seem different based on how algebraic rearrangement is done:

$$
  X(z) = \frac{\left(\frac{1}{2}z^{-1}\right)^5}{1-\left(\frac{1}{2}z^{-1}\right)}
         = \frac{1}{(2z)^5-(2z)^4}
$$

Clearly \$\frac{1}{2}\$ is a pole based on either rearrangement. Is zero a pole as well?

Is there a general rule of thumb for how to do algebraic rearrangment to measure zeros and poles?


texts:
I'm experimenting with the 434 MHz RF Link transmitter (WRL-10534) from SparkFun. I'd like to determine the peak-to-peak voltage of the RF output, but I don't have access to an oscilloscope that can measure this signal. The datasheet for the transmitter says that the output power is 14dBm. The transmitter's supply voltage ranges from 1.5 ~ 12V so I assume the 14dBm spec is full power when operating with a 12V supply.

Can anyone suggest how I can determine the peak to peak voltage of the RF output?


texts: Capacitor voltage divider in quasi-DC circuit

texts:
In the below image, I show two circuits, both fed by 50Hz AC.

In the top circuit, it is possible to continuously draw current across the point marked in red.

Does that remain the case on the bottom circuit? If so, how does this work?

[EDIT] Also - would the voltages across both capacitors remain equal?


texts: I need help with determining voltage wave form of LM317

texts: Now I calculated Vout as being 5V, so is the Vout wave form the same as Vin?


texts: Is there a way to make an LED blink using a passive circuit?

texts:
I am trying to make a simple flashing LED toy to get a 5-year-old boy interested in electronics.

The LED should blink for the shortest time possible
Remain off for several seconds between flashes
The battery should last as long as possible
No transistors or integrated circuits

This post offers several circuits, but they all require transistors or ICs.* Surely, there is a way to make an LED flash intermittently without any ICs or transistors? Besides the compulsory timing resistor and capacitor, diodes are fine.

I made a novelty flashing light years ago, which used an NE-2 neon lamp, a capacitor, and a resistor. Powered by a couple of unobtanium 67.5 volt batteries, it would flash every ten seconds or so. It did that for many years, until the batteries were exhausted. When the capacitor across the lamp reached the lamp's ionizing voltage, the capacitor discharged until the next cycle.

Now, while LEDs certainly have different characteristics than a gas lamp, there should still be a way to make it flash like the neon lamp did using only passive devices (with the exception of some diodes). How can this be accomplished?

Are there any suitable tunnel diodes for this?

I couldn't find much information in a Google search.

From this webpage.

In my experience, LEDs glow with just a few mA.

* Only later can we introduce him to active devices. (Long story.)


texts:
Is there an open source version of the MOST protocol?

From the above link:

MOST (Media Oriented Systems Transport) is a high-speed multimedia network technology optimized by the automotive industry. It can be used for applications inside or outside the car.

The serial MOST bus uses a ring topology and synchronous data communication to transport audio, video, voice and data signals via plastic optical fiber (POF) (MOST25, MOST50, MOST150) or electrical conductor (MOST50) physical layers.

MOST technology is used in almost every car brand worldwide, including Audi, BMW, Hyundai, Jaguar, Land Rover, Mercedes-Benz, Porsche, Toyota, Volkswagen and Volvo.


texts: Generating high voltage (100V+) from 5V USB supply

texts:
I am using an USB port as a power supply. Is there a way I can take the weak 5V of a regular laptop USB and transform if to 100V+ while begin in the smallest package possible. I've heard of boost converters but they are usualy too big. I want something that has the size of like a normal USB key.

What I want to do is to charge up around 5 capacitors at 100+V and then discharge them later. Power efficiency not a concern for me.

It would be helpful to include a schematic of the circuit.


texts:
How do I estimate the output jitter of a clock tree consisting of a clock oscillator followed by a clock buffer?

The components have the following jitter characteristics:

The clock oscillator has a total jitter of J1 = 25.6 ps (peak-to-peak), consisting of 1.3 ps RMS of random jitter and 6.7 ps P-P of deterministic jitter
The clock buffer has an additive jitter of J2 = 350 fs RMS


texts: Trigger PTT on Baofeng UV-5R with Arduino

texts:
A current project of mine is to have the Arduino Uno play an audio file off an SD card module. The audio file would come out of the Arduino and into a Baofeng UV-5R handheld transceiver. The first thing that needs to happen is Arduino would trigger Push-To-Talk(PTT) on the radio and then input the audio. I will post the pinout diagram of the 3.5mm jack. My question is can I send in a normal audio file or should I convert the file to a mono low bit rate and/or Hz file.

This is my first post here, so if a drawing or anything is need please let me know.

Thanks for the help.


texts: System Grounding and Mixed Supply Grounding

texts:
I'm attempting to prototype this curve tracer (http://www.vintage-radio.info/download.php?id=224) mainly following the original design, but altering it to suit my own requirements (serial connection to PC instead of oscilloscope, etc).  I've been stung by grounding issues with measurement circuits before, so I thought I'd share this with the community first to avoid any major gaffes.

Here is a high-level component diagram showing my plan so far (click to expand).

Each component box represents a potential circuit board.  I'm planning to use a combination of stripboard and copper plane (Manhattan) for the boards.  The diagram is a bit of a mess, but essentially there is an effort to separate analog from digital, with separate supplies and a star ground.  I've tried to follow best practice regarding the mixed signal board containing the ADC, but I'm not sure I'm there yet and I have a specific question (see below).
The main issue I'm faced with is that some components like the step generator use both analog and digital supplies.  The step generator is composed of a pulse generator and a counter (both fed from the 5V digital supply) feeding an array of transistors having the analog supply across the CE junction.

Here's an snip of the step generator for reference:

So, my questions are:

1) Regarding components using both digital and analog supplies (like the step generator), what is the best practice approach to grounding?  It seems difficult in this case to avoid having the 5V TTL signal at the transistor base polluting the analog supply.

2) Regarding the mixed-signal ADC board.  Having done some research it seems the advice is to power the ADC using the analog supply.  Since the ADC requires a 5V supply, does this mean I'll need yet another regulator to create 5V from the +12V analog rail?


texts:
I need to know if there is a way to merge two or more polygon pours of the same type, in order to have only one. So two objects that become one. Is this possible?
Because anytime I need to redefine a polygon I do not want to start again if I only need to add and improve a little part of it.


texts: How does ohm's law for capacitors affect this scenario?

texts:
Ohm's law for capacitors is i = C dv/dt

simulate this circuit – Schematic created using CircuitLab

Clearly there's a zero change in voltage across C1 always, but since C1 is a capacitor, it can hold charge and the current is not zero.


texts: Is it okay to connect 2 lithium ion battery in parallel to a charger that can maintenance 4.2V? (more detail in post)

texts:
So I'm planning to make a charger that can charge multiple lithium batteries in parallel with hope to use recycled one. I fully understand that they are dangerous when you do it incorrectly, so I just want to make sure first.

My design involves the batteries have common ground and each of the positive has a MOSFET, each of which is controlled by an Arduino

simulate this circuit – Schematic created using CircuitLab

I can individually address the batteries by opening and closing the MOSFETs.
My question is how can I charge the batteries as quickly as possible. I can just charge one at a time and discharge 1 at a time, but that seems inefficient.

My plan is to charge all the battery individually until the voltage meter reach 4.2V (The battery voltage can be like 3.9 or 4.1, but the charger keeps it at 4.2). Once all of them allow the charger to stay at 4.2V, open up all of the gates and charge all the battery in parallel. This is the part that I'm unsure. Since the voltage of the charger will remain at 4.2V, this shouldn't be a problem right?

In case the charger got disconnect, all of the gates will close to isolate the battery. The Arduino will then read each of the voltage of the batteries by open the corresponding gates, finding batteries that are at 4.2V and open those gate to discharge. This would also won't cause a problem right?

Edit: I'm actually gonna use a shift register powered at the right voltage to control the MOSFET, I just simplified it with the Arduino


texts:
I need to control motion direction of linear actuator. It works off of 24V power supply, and if i switch polarity of supply it goes to opposite direction. The supply for actuator is simple DC with no PWM.

I try to switch power to actuator with this circuit:

Basically actuator has two terminals which connected (through SSR) to OUT_H and OUT_L. U4 is the simple inverter and U3, U5 gate drivers. The DIR signal goes from MCU and control direction of motion.
I assume that when the DIR = 0 i would have OUT_H = 24V and OUT_L = 0V, when DIR = 1 - OUT_H = 0V and OUT_L = 24V.

Is my assumption is right for this kind of application, or i'm missing something?


texts: DC motor as a generator: characteristics

texts:
I am using a DC motor as a generator for my small toy/experiment. The problem is that the motor/generator can not provide enough counter EMF or torque or whatever the correct word is. So the rotor on the other side just keeps spinning at too high RPMs. I would like to control the rpm of the rotor to do so I will change the motor. My question is what is the right characteristic to check while buying the new one. Power supply (Watt), the speed constant (RPM/V) , the supply voltage (V) and torque constant (mNm/A)

Clarification:

I am using it with a small wind turbine model. It is connected to a circuit where I can play with the resistance. I change the resistance and read the voltage output by that I get the power extracted. It is being extracted, so it should be connected correctly I guess. But the resistance range of 10 to 10000 Ohm at a constant incoming wind speed, the rpm of the rotor only changes from 5000 to 5200. surely The RPM goes higher with an increasing incoming wind speed but the change of rpm with same resistance range is very limited. so somehow the counter EMF is not enough need to buy a new motor?

Right now the characteristics of the motor I am using:

Maxon RE 10 Ø 10 mm,
Precious Metal Brushes,
0.75 Watt Values at nominal voltage
Supply voltage 12 V
No load speed 11500 RPM
No load current 5.37 mA
Nominal speed 2790 RPM
Nominal torque (max. continuous torque) 0.731 mNm
Nominal current (max. continuous current) 0.081 A
Stall torque 1.01 mNm
Starting current 0.106 A
Torque constant 9.55 mNm/A
Speed constant 1000 rpm/V
Speed / torque gradient 11900 rpm/mNm


texts:
I have a question from exam that I failed to solve:

I need to build a digital logic circuit that is receiving 4 bit number and return true if the number is 0, 7 or 14.
I have only one XOR gate (2 inputs), one NOR(3 inputs), one NAND(2 inputs) and one 3-to-8 decoder.

I think that question is unsolvable, I didn't find any combination that can do that.
Any idea how to solve it?


texts: Reduce noise in this op-amp buffer circuit

texts:
I am using this op-amp circuit to buffer voltage (0-5V) received from MCU.
Resistors at the output are used to limit the current controlling the solid-state relay. However, (Vin) coming from MCU is noisy and as a consequence (Vout).  This makes the operation of the SSR unstable. How can I reduce or avoid this noise. Vin is an on-off square signal of maximum pulse duration of 20ms, to switch the SSR on and off.

Edit:

A view of the PIC circuit is given below, Vin is taken from A0 pin.
Next, a view of the noisy Vin signal taken from Oscilloscope is shown.
And a zoomed view of this signal at the high-to-low change is also given.
I am sorry for combining all images in a one, because I am not able to attach more than two images in this question.