texts: Increase gain of electret microphone amplifier powered by aircraft radio?

texts:
I am trying to build an amplifier to allow a cheap electret boom microphone to be used with an aircraft radio, but am unsure how to increase the gain to a usable level.

I derived the attached design from experimentally trying this Circuit to make an electret microphone simulate a carbon microphone and Andy AKA's electret microphone amplifier design, neither of which had sufficient output when tested in the aircraft, and experimenting with schematic changes and component values in LTSPICE.

The attached design works though the output is lower than required when using a normal voice, but when speaking very loudly the output level matches the output level of commercially available aviation headsets and the signal is still very clear and intelligible.  This tells me this amplifier can easily drive the aircraft radio's input but lacks sufficient gain to be driven by this microphone.

My previous attempt used a single 2N3904 (measured hFE = 110) and had the same problem of low output.  Replacing the 2N3904 with an MPSA13 darlington (hFE = 5000) had no noticeable effect on the amplifier gain.  I don't know enough about this stuff to understand why. How can I increase the amplifier gain without adding another transistor stage before the MPSA13?  Cost isn't a factor but component count is as this amplifier will need to be made much smaller, and it seems absurd to require another stage when the MPSA13's gain is already so high.  What am I missing?

I don't have access to an oscilloscope to measure actual signal levels and can only test each design in the aircraft, so there's a lot of guesswork involved.  Any help will be greatly appreciated.

@Olin Lathrop - I simulated your amplifier design in LTSPICE (see image)


texts: Pulse frequency modulation mode in buck converter MAX15062

texts:
I am modelling MAX15062 DC-DC buck converter using datasheet in PSpice, initially i worked on control loop. This buck converter has two modes PWM and PFM mode. With MODE pin unconnected works on PFM mode which changes its frequency and prevents inductor current from reaching negative at light load condition.
How does it enter, sustain and exit this mode.
I ran a load step analysis for MAX15062 testcase schematic designed from Maxim integrated website- downloaded the schematic and ran in EEsim (simulator).

Here Vin=24V and Vout=5V
Load current is varied from 300mA to 10mA

This is kept in PFM mode, where it dosent allowes inductor current to go negative by keeping highside FET and lowside FET off for some time.

It also skips some of the pulses and again recovers back and allows some pulses.

In light load condition max current is limited to 150mA.

I am sharing some screenshots of LX (Inductor node switching), Vout , IL(Inductor current),and schematic of the test case.

Datasheet of MAX15062

Reference for PFM mode


texts: Induction motor: T-Slip Characteristics look weird

texts:
I was recently doing a first-course lab on Induction Motors.
We were asked to plot the torque-slip characteristics of a 4-pole 3 phase induction motor (3.7kW).

I just analyzed the data I plotted from the wattmeter readings (connected as shown below) and the rpm measured using a tachometer.

Here's the T-slip data I plotted on my spreadsheet.

Data points were obtained by gradually loading a mechanically coupled DC generator.

I don't think my plot looks anything like the t-slip diagrams from my lectures and even Google Images.

Can someone who knows what's going on explain it to me?


texts: What is the equivalent of a buck converter for AC voltage?

texts:
A have researched and found that a buck converter is used for stepping down voltage in DC applications.

However, my application uses AC current. I have christmas lights that plug into the wall and I wanted to remove some bulbs. Now I am using a resistor, but I don't want the resistor because it is hot so I considered stepping down the voltage to achieve this without the device getting hot.

So how can I step down voltage on an AC application? Essentially, this would be the equivalent of a buck converter which is used for DC applications.


texts: How to know the part number that I want?

texts:
I am new to electronics. But I got to know how to make circuit and make it work. Problem I am facing, I need to know the part number based on my requirement.

Suppose if I want to buy an AND gate which works at 9 Volts, then what is the part number for it? How can I find the part numbers that I want? Can I find it on the internet?

It might be silly question for many of you... unfortunately it is bothering me a lot how to know the part number...


texts: How to tap out video signal from a computer or a TV

texts:
I am designing a TV transmitter as given in the link below:

http://www.electronicshub.org/tv-transmitter-circuit/

My question is, where from do I give the video input? For the audio input, I can simply connect an audio jack to the audio out pin of the motherboard. What do I do about the video? Video output from the motherboard is  trough the VGA pin. How do I tap out the video signal from the computer and feed it to this circuit? Please provide any simple technique.


texts: In an isolation transformer, to what is the electrostatic shield winding attached?

texts:
In the following diagram of an isolation transformer,

found on Wikipedia here for the diagram and also here for the definition of Isolation Transformer, there is a special winding in between the primary and the secondary described by "Single layer winding used as electrostatic shield", that I assume channels electrostatic discharge (ESD) away from the secondary.  It must be connected to something, but what?  Is it grounded to the body of the transformer?  Obviously, whatever it is connected to cannot defeat the isolation function of the isolation transformer.  And can the "winding" be just a strap?  Or is its isolation also magnetic in nature, or have a filtering aspect to it?


texts: Transmission line model VS lumped parameters models

texts:
Both the lumped parameters models vs transmission line models use RLC components for modelling.
This is where I am confused and cannot see the difference between the two.


texts: How to calulate mosfet response time with load?

texts:
I would like to calculate the response time of a PMOS circuit and of the circuit

Could you tell me how to do it?

I'm using this transitor.
https://www.infineon.com/dgdl/Infineon-IRFR6215-DS-v01_02-EN.pdf?fileId=5546d462533600a40153563595592114

I tried to use the rise time of the PMOS to find it can switch (and i don't know if that's the good way), but I don't now the results with the load. CL en RL.
I assume CL at t=0ms is equal to 0V. I tried to use dv/dt, but I failed
VIN1 = 28V.
VCMD is a command

Thanks.

edit: I made a mistake. The Zener is also connected to the source. Sorry


texts: Is plugging a wrist strap in enough to prevent ESD?

texts:
I've been told by a few people that if you plug in a PC and switch off its power supply that it is enough to prevent ESD.

But I was taught differently. I was taught that it's more about difference in potential rather than grounding. The way I was taught was that everything must be unplugged, placed on a matt with a grounding strap for the matt and the installer.

If a person follows method 1 will it still cause ESD damage?


texts: nanoPower comparator driving MOSFET not providing expected output

texts:
I built the following circuit to charge a large capacitor from a low power source before switching the load:

simulate this circuit – Schematic created using CircuitLab

MAX9064, MCH3484, MCH3383.

The MAX9064 has an internal REF of 0.2V and the resistor network should be triggering it on at 1.5V and off at 1.1V.

I think I may have messed up with the MOSFETs, as they are both Power MOSFETs? In any case, the circuit doesn't work properly. I get 0.5V at Vout with C1 removed. With C1 in place it charges way too slowly, but I'm still seeing a slowing rising mV value at Vout instead of 0V like it should be.

I'm thinking that either 1) I've used the Power MOSFETs incorrectly or 2) There just isn't enough current for it to function (but these are all super low current devices so it should?)

If it is the Power MOSFETs, is there a way I can make them work in this circuit or do I need to get different ones?

Note: I'm using the MAX9064 which has push-pull output. At 1.8V it is supposed to supply Vcc - 0.15 to 0.23. So it's output at the switch on voltage should be around 1.3V. M1 only requires a drive of 0.9V which it should be supplying.


texts: Switch for low voltage, high current Shape Memory wire

texts:
I need a switch to allow current to pass through a wire to Joule heat it. This is a nickel-titanium wire (Shape Memory Alloy, SMA) which has been programmed to bend into a particular shape when heated. Unfortunately, this SMA wire is fairly large and rather low resistance (~0.6 ohm), so to heat it properly I am using about 3 amps but only 2 volts.

I would like to be able to turn the current on and off with a control signal as needed to maintain a desired temperature. Transistor solutions seem to be either too low current or too high VDS (> 5 V).

I have stumbled onto possibly two solutions, using PWM with an H-bridge, or using a buck converter, but I am having a hard time understanding why one would be better than the other or if they would even work.


texts: Using two pressure sensors with same address over I2C

texts: I'm a novice programmer and I have recently purchased the SparkFun Pressure Sensor Breakout - MS5803-14BA and used it to take pressure readings quiet easily with the sample code provided and an arduino uno. However, I actually need to hook up two pressure sensors to the arduino and get two pressure readings for measuring the pressures inside a pressurised vessel. Does anybody know how I could extend the current example code provided to give two pressure readings?


texts: Using a single MOSFET to switch current direction

texts:
I am currently using a 30N06L MOSFET in order to control a DC engine from an Arduino using this circuit:

The problem is that this way I cannot change the direction of the engine.

Is there a way to also be able to change the direction of the engine (e.g change the direction of the current), using another MOSFET? We have only 2 mosfets, and do not have any special drivers..

Maybe it is possible to connect another similar circuit (in parallel to this one), with the voltage switching legs in the second mosfet, and then by controlling that mosfet turning the engine in the other direction?

Thanks.


texts: How to switch a Bluetooth module with a P-Channel MOSFET high-side switch?

texts:
I am looking for a high side switch to turn a Bluetooth module off when not in use.
The module uses 100mA at most and runs on 3.3V.
I am using a ATMega328 to talk to the module and it runs at 5V.

How can I use a P-MOSFET in a high-side switch circuit to switch these low current levels using 5V logic?

Lacking the ability to add an answer:

Would this work, perhaps?

simulate this circuit – Schematic created using CircuitLab


texts: Simple digital circuit schematic question

texts:
Below you'll find the schematic for a circuit I have to build and analyze tomorrow for a lab.

simulate this circuit – Schematic created using CircuitLab

(Note that the blocks I've shown labeled "+5V" are not accurately drawn; the symbol my instructor uses is a triangle, but I couldn't seem to find it in the editor.)

Firstly, will I require three separate +5V supplies to build the circuit I've shown? In the lab we use a rack-mount power supply, so my guess is that one would be acceptable since a voltage source (ideally) should output the same voltage regardless of the circuit it's hooked up to. Is this logic correct? Not seeing a physically connecting loop in a schematic always throws me off.

Secondly, are the grounds going to the same place? How does one tell? Towards the end of last semester in the lab we built some circuits with floating (also called virtual I believe) ground, and I never got a full understanding of the idea itself.


texts:
Is the conductive thread non toxic?

Safe to wear up against your skin for extended periods of time?


texts: After research, how should I go about creating a bluetooth peripheral?

texts:
My goal is to create a very simple (1 input, 1 output, both high / low states) bluetooth peripheral to be worn on the wrist to connect to an android phone running Lollipop. I have the following requirements:

Use either the bluetooth 4.0 or 4.1 standard
As low power consumption as possible
Small form factor (worn on the wrist)
Low cost - this is partly as a challenge for myself to find the lowest possible cost to achieve this

With the above in mind, I have come up with the following options:

Use an integrated arduino / bluetooth module (e.g. Blend Micro). This should be easy to do, but falls down on the form factor and cost
Use a serial bluetooth module (e.g. Tinysine's) with a simple programmable chip, such as the PICAXE. This is cheap and has a low form factor, but after researching some of the available bluetooth module options, the datasheets appear to be extremely unhelpful and out of date
Use a programmable propriety bluetooth module (e.g. Rayson BTM-840B). This should be the smallest and lowest cost, but upon research I am not too sure how to actually purchase any of the supposed options, or actually load my own code on them.

Are there other options that I have not considered? With regards to the third option, what accessible products are there available for this specific purpose, and how can I program them? I am very open to more 'difficult' programming environments, but I am not sure where to even start with this particular scope.


texts: I want to understand how does this 2-transistor circuit work. It is used in a schematic for increasing the current rating at the discrete output stage. This does not look like a standard darlington configuration. Is there any specific benefit of this 2-transistor circuit over a standard darlington pair? Can we remove 'R2' from the circuit? It looks like not doing any useful work. Also what can be the benefit of 'C1' capacitor?


texts:
I am currently trying to make an LED music visualizer that goes to music and attaches to my headphones. The ideal solution would be to have the LEDs run from the audio circuit from a smartphone (with a battery I would charge adding extra power), but I have also considered drilling a hole through my over-the-ear headphones for a small mic. So far, I haven't had that much luck, but I stumbled upon this circuit diagram:

This seems to solve some of my problems but I can't figure out whether it analyzes each frequency or if all the LEDs would bounce at once. My main question, though, is how I would use this and my heap homes at the same time. Should I use a splitter to get two audio signals? Is there a way I could add more power and connect the headphones through this circuit to still hear music? Any help is greatly appreciated.


texts: ASK modulator using transistor not working properly at high frequencies

texts:
I am trying to make a simple ASK modulator circuit using an npn transistor. It works acceptably at lower frequencies. However at higher frequencies, it doesn't work properly. The amplitude of output wave when supposed to be 0, is nowhere near to 0. PFB the images showing the circuit and the simulation diagram-

The software used is multisim on a windows machine.

Blue is the carrier wave of 27MHz
The red digital wave is 150 khz that is to be ask modulated.
Another red wave is the output wave whose amplitude is clearly non zero for the negative cycles of the digital wave.

Both the input signal's are 3V at peak levels.

Additionally, output wave's +ve amplitude is as much as carrier but not the -ve one.

I don't have much of domain knowledge in this field. I tried searching, but most of the text is out of my understandable levels. Kindly help me achieve the desired output.

EDIT 1-

Modified the digital signal to range from 0 - 3V. The waveform produced is like -

EDIT 2 -

As per Peter's suggestion, biased the carrier wave to range from 0-6 V. PFB the waveform. It's much better, but still not the ideal as shown in the texts.


texts: Why do we use alternating current and not direct current for mains power plugs within a house?

texts:
I understand that for transporting electric energy it makes way more sense to have AC. But within my house, I don't think that argument holds any more.

Devices I use (roughly ordered by power consumption):

Stove / oven: Isn't connected to the usual power plugs anyway, but a "high power" one
Washing Machine: max 900 W
Micro Wave: 800 W
Hand mixer: 450 W (I was quite surprised by that)
Fridge+Freezer: max 110 W
Laptop (usually 50 Watt, max 90 Watt)
Smartphone: 15 W?
electrical shaver: < 10 W
LED lights: 3 W
alarm clock: ?
Charging USB 2/3 devices

I've just seen that the car charger cable for my Notebook is WAY smaller than the one for the usual power plug. Looking at the power supply unit of my laptop, I see that it outputs direct current.

Seeing this huge difference in the size of the charger unit (and the price as well), I wonder why the usual power socket does not provide DC, but AC. What are the advantages within a house to use AC? Why wouldn't it be a good idea to have DC power plugs (e.g. as in cars)? (I've also heard that solar pannels provide DC).


texts: What is this device and what does it do?

texts:
I have this device here and I do not know what it is or what it is used for. I literally found it on the ground of a store parking lot.
I've attempted to research the item and I think it is a tool used for debugging. I also have not a clue what debugging is in even a slight sense.
Some characteristics:

It has 2 connectors

One connector is a standard android jack
The other is a 20 pin jack

It has 1 button

Any info on this device is appreciated.


texts: Issues with designing ground plane for switching relays in high noise environment

texts:
I am designing a PC Controlled 8 channel Relay using AVR microcontroller.

Here, the relays are on the right side of the board and are controlled by the AVR micro on the left side.

The eight TTL outputs from AVR are connected to a high current darlington pair IC like ULN2003A.

I may use either USB or RS485 interface to connect the board with PC.

Each relay is rated up to 7 A AC switching and there are eight of them. The relays are used to control AC electrical equipment.

PCB is double layered FR4 material.

The green layers in the below image represents the ground plane. The AVR microcontroller section has ground plane on both sides.

I want the circuit to work reliably in a high noise environment without resetting the AVR micro.

Both Micro and relay drivers are powered by a single 12 V DC adapter. 12 V DC to 12 V relays and 5 V to micro through a linear regulator.

Now my questions are:

Should I keep the ULN2003 close to the relays, so that the length of
the high current traces going to the relay remains short and make the
TTL 5V lines to the ULN2003 long or vice versa? Which is better?
Do I have to extend the Microcontroller ground plane under the TTL 5 V
lines going towards ULN2003 as shown in the above image also or
should I leave them without a ground plane (under the TTL 5 V lines
only)?
Do I have to provide a ground plane under ULN2003A IC and the relay DC contacts?

Other Suggestions about proper ground designs are welcome.


texts: How current run in conductor by electrons

texts: When we connect neutral to ground, why doesn't an electron deficiency occur in the conducting power lines. I know current in a conductor is made up of flowing electrons but when this current is flowing into ground, then the electrons in that conductor must be flowing into the ground as well.  Why doesn't this result in a depletion of electrons in the electrical grid?


texts:
I am trying to measure current thru load from 1 mA to 10 A at 1 mA accuracy. I am using a 10 mΩ current shunt. I was also thinking of doing a low-side measurement (since input voltages can get to 100 V). I basically want to measure DC currents or pulsed currents as high as I can get. I've read thru numerous documents and became out more baffled than I was before, ADC really is a complex subject (or maybe its just me :-P).

So basically I need 14-bit ADC but since those are rather rare I decided to look for a 16-bit and found ADS1148 which is a 16-bit 2 kSPS \$\Delta\Sigma\$ ADC.

With 10 mΩ and 1 mA going thru it I get 10 μV across the current shunt resistor. Or 10 μV/mA.

With an external reference of 2.048 V, I get \$ \frac{2\times2.048}{2^{16}}= \small 62.5 \mu V\$ of resolution, I could further use a x16 amplifier and thus get 3.9 μV of resolution or 390 μA.

Analog input voltage range is +-Vref (thats why 2*Vref), so if I have Vref+ connected to 2.048 V and Vref- to 0 V I can read voltages in +-2.048 V range? Or will those values below Vref- read as 0x00?
Since this particular ADC has internal PGA can I connect its inputs directly across current shunt and set gain to something like 16 V/V? Or is it better practice to connect differential amplifier across current shunt amplify the signal and then measure its voltage via ADC (in this case I only need single-ended ADC?)? (the diff amp will still be present tho since I already need it for something else)
62.5*16=160 μV seems rather low to me, is this in the range of "normal" noise floor? Will I really get 16-bits of accuracy from this? (I am highly skeptical of this) But if I connect a differential amplifier across the current shunt I am also amplifying this noise (or am I not because of high CMRR)? If not how can I calculate what CMRR I need to achieve 16-bit accuracy?
At page 15 in the datasheet there are noise and ENOB tables. But refeering to MAXIM definitions ENOB is in this case really Noise-Free Resolution? Following from this, at PGA gain of 1 (using external differential amplifier) and 640SAS I can expect 15.4bits of noise-free resolution or \$\frac{2\times2.048}{2^{15.4}}= \small 94.7 \mu V\$ or 9.47 mA or accounting for x16 amplification about 592 μA of resolution?

I apologize in advance if this is too long of a question, but I've just not been able to understand these concepts on my own.


texts: Eagle is refusing to tie ground pads of SMD components to the ground plane

texts:
So, long story short, I copied Eagle's standard RCL library to prune it down to the SMD essentials and to verify the packages.  I removed the old library entirely, so it's not even loaded anymore, and loaded mine and replaced all relevant components in my schematic with a new version from my library.

Now, when I updated the schematic and told it to do a library update, it updates my board.  That's fine.  However, when I run a ratsnest, it unties the ground pads from the ground plane.  What used to be 3 "prongs" from the pad tied to ground from the ground plane is now a single "prong that isn't even fully attached.  Also, the ground plane will no longer run between the pads like it would before on the top side...  and it puts a hole in the ground plane on the other side of the board.

I'm completely baffled on what would cause this.  It's happening consistently with the packages I've modified.  The only things I've changed are: updated pad sizes, moved the outline of the actual part to the Dimension layer, and added a courtyard in both tKeepout and in tPlace.  I tried removing the courtyard lines from tPlace/tKeepout to no avail.

Here's a picture of what Eagle is doing:

Please help.  I'm so friggin' baffled. :(


texts: STM32F407 Discovery CAN Bus RX interrupt doesn't fire

texts:
I am designing a CAN Bus with two STM32F4 Discovery boards. I use transceivers SN65HVD234 from Texas Instruments. I configured the Discovery with CubeMX and used CubeIDE. I am using the HAL library.
I use the User button to fire an EXTI interrupt, that calls HAL_CAN_AddTxMessage() and writes on the bus.
Transmitting data works, but not receiving. Only receiving in loopback mode works for a board that self-transmits.
The hardware is working very well (confirmed with scope ) and I saw various people having the same problem on other boards, like in this discussion. As I didn't really understand the solution, here is the configuration of my filter :
CAN_FilterTypeDef  sFilterConfig;
/*## Configure the CAN Filter ###########################################*/
 sFilterConfig.FilterBank = 1; // config seen in [STM32F4 ref manual][2] p1089
 sFilterConfig.FilterMode = CAN_FILTERMODE_IDMASK;
 sFilterConfig.FilterScale = CAN_FILTERSCALE_32BIT;
 sFilterConfig.FilterIdHigh = 0x0000;
 sFilterConfig.FilterIdLow = 0x0000;
 sFilterConfig.FilterMaskIdHigh = 0x0000;
 sFilterConfig.FilterMaskIdLow = 0x0000;
 sFilterConfig.FilterFIFOAssignment = CAN_RX_FIFO0;
 sFilterConfig.FilterActivation = ENABLE;
 sFilterConfig.SlaveStartFilterBank = 2;

 if (HAL_CAN_ConfigFilter(&hcan1, &sFilterConfig) != HAL_OK)
 {
     /* Filter configuration Error */
     Error_Handler();
 }

I tried to apply a config seen in the STM32F4 ref manual p1089, but I can't see any way to configure the filter number...
What did I do wrong? I think it could help other people because my design is very classic, using one CAN in normal mode.


texts: Boost converter, once enabled, can't be disabled

texts:
I'm attempting to interface a TPS61235P boost converter to an Arduino Pro Mini (3.3V Vcc), and while I can get it to turn on, I can't for the life of me get it to turn back off.

I currently have a 1M resistor pulling it down, and a 10k resistor to an output on the Arduino.

Before driving the pin high, the converter is (correctly) disabled. When I make the pin go high, it turns on just fine.  But when I turn the pin low, figuring it'd pull it to ground combined with the 1M resistor, the converter stays on.  On top of that, my code indicates the OUTPUT pin state is high as well, despite me setting it low (I have an OLED display on the Arduino).

The enable pin stays at 5.15V constant, despite originally only supplying it with 3.3V. Its almost like it feeds itself, because not even the Arduino can drive it low, I must ground it with a wire and then it stays low, even after disconnecting the jumper wire.

If I disconnect the enable pin from the Arduino, the output pin switches as it should to low.  It reads high again the moment I plug it back onto the enable pin of the converter.

Even with jumpering resistors to the enable pin, the only way I can get this thing to turn off is to jumper it to ground with a wire, no resistors.

What's going wrong?

simulate this circuit – Schematic created using CircuitLab


texts: How to design mutual inductor in proteus for wireless charging?

texts: While designing the wireless charger, i've designed the circuitry in proteus. And it begins with the use of the dc voltage, then the oscillator and finally the transmitter circuitry and the receiver circuit.The problem arises how to design the mutual inductance between the transmitter and receiver circuit in the proteus.I can't find out the right component for it in proteus. What might be a way to accomplish it?


texts: Need to get more analog inputs Arduino Uno

texts:
Im making BattleShip on the Arduino:

2 x grid ((10x10 push buttons) +  (10x10 led 5mm))
2 x grid ((10x10 reed switches) + (10x10 led 5mm))

I made a 10x10 grid of push buttons by setting 10 buttons in a row with resistors on each button. By putting it on 5 Volts, each button give an other value of volt to Arduino when pushed.

In this case I got 10 cables from 1 x 10x10 button grid. total 4 grid (40 cables with analog input)

now my question is how to hook up those analog input wires to the Arduino UNO. Can you help me out here? Thanks

/e

im using 1 analog pin to hook up 10 buttons (in code 5 buttons).

Code:

for (int i = 0; i < 10; i++){

  if      ((voltage[i] >= 0.35) && (voltage[i] <= 0.50) && (gameStatus[i][0] == 0)){ gameStatus[i][0] = 2;}
  else if ((voltage[i] >= 0.35) && (voltage[i] <= 0.50) && (gameStatus[i][0] == 1)){ gameStatus[i][0] = 3;}
  else if ((voltage[i] >= 1.40) && (voltage[i] <= 1.60) && (gameStatus[i][1] == 0)){ gameStatus[i][1] = 2;}
  else if ((voltage[i] >= 1.40) && (voltage[i] <= 1.60) && (gameStatus[i][1] == 1)){ gameStatus[i][1] = 3;}
  else if ((voltage[i] >= 2.40) && (voltage[i] <= 2.55) && (gameStatus[i][2] == 0)){ gameStatus[i][2] = 2;}
  else if ((voltage[i] >= 2.40) && (voltage[i] <= 2.55) && (gameStatus[i][2] == 1)){ gameStatus[i][2] = 3;}
  else if ((voltage[i] >= 3.65) && (voltage[i] <= 3.80) && (gameStatus[i][3] == 0)){ gameStatus[i][3] = 2;}
  else if ((voltage[i] >= 3.65) && (voltage[i] <= 3.80) && (gameStatus[i][3] == 1)){ gameStatus[i][3] = 3;}
  else if ((voltage[i] >= 4.30) && (voltage[i] <= 4.60) && (gameStatus[i][4] == 0)){ gameStatus[i][4] = 2;}
  else if ((voltage[i] >= 4.30) && (voltage[i] <= 4.60) && (gameStatus[i][4] == 1)){ gameStatus[i][4] = 3;}
}


texts: Using the same power source for microcontroller (arduino) and rest of the circuit?

texts:
I have an Arduino, it controls a 6V DC motor and 12V DC solenoid (which only really needs 7V for what its doing).

Originally I wanted to use 1 rechargeable 7V battery (or 9 or whatever the closest I can get) to power all three of these.

But I've been seeing recommendations from people to use separate power supplies for Arduino and the rest of the circuit, otherwise they describe a lot of "noise" when the motor and solenoid suddenly engage. (not sure what is meant by "noise")

So is there a way to accomplish my task with one 7 - 12V power supply??


texts: ATMega644PA possibly bricked by setting fuses with avrdude

texts:
I have been programming an ATMega644PA with avr-gcc and avrdude on linux for a little while with no problems. Well until I decided to change some fuses. I had been using the option for avrdude -p ATMEGA644P for programming the chip even though the chip is ATMega644PA.

After reading the data sheet (and reading the fuses on the chip) I did the following

avrdude -v -c avrispmkII -p ATMEGA644P -P usb -U lfuse:w:0x63:m

The chip would no longer communicate. I realized after that the problem may have been that I set the bits for external clock rather than crystal oscillator but even with using an ATTiny to generate a 1MHz signal to the proper pin on my Mega644, I still get nothing.

Any ideas as to why the chip is unresponsive? Could it be that using avrdude's definition for the P version of the chip rather than the PA version is the cause?

And finally, What can I do to rescue my chip? Ive heard that it may be possible with High voltage programming or JTAG. Would I be able to do that with an STK500?


texts:
In my project i am using an ultrasonic transducer. The transducer has a high Q-factor so that it's zero input transient responses decay rate is quite low and i am suffering from that because the transient is interfering with the reflected signal.

Here is the circuit that i am using, C0 L1 R1 and C1 accounts for the transducer

It has the response

where green is Vin and red is Vout

In a linear time invariant circuit,

\$
\frac{d}{dx} \overline{x}(t) =\overline{\overline{A}} \overline{x}(t)  +  \overline{b} v_{s}(t)
\$
where
 \$
v_{s}
 \$
is the source and
 \$
\overline{x}
 \$
is the state vector then we have,

\$
\overline{x}(t)  =  e^{ \overline{\overline{A}}t} \overline{x}(0) +  \int_0^te^{ \overline{\overline{A}}(t -  \tau) } \overline{b} v_{s}( \tau )d \tau
 \$

, i wonder if for any input
 \$
v_{s1}(t), v_{s1}(t)= 0~~ for~~t > t_{1}
 \$
there exists a function
 \$
v_{s2}(t), ~~v_{s2}(t) \neq 0~~ for ~~t_{1}\leq t\leq t_{2}
 \$
such that
 \$
    \left\{
\begin{array}{ll}
      v_{s}(t) = v_{s1}(t) & t\leq t_{1} \\
      v_{s}(t) = v_{s2}(t) & t_{1}\leq t\leq t_{2} \\
      0 & o.w. \\
\end{array}
\right.
 \$
 \$
,\overline{x}(t_{2}) = 0
 \$

That is to say, i want to apply a signal right after the original signal so that the latter will suppress the transient created by the first. I have found analytical solution for
\$
v_{s2}(t)
 \$
if
 \$
\overline{b}
 \$
is an eigenvector of
 \$
\overline{\overline{A}}
 \$
but i am seeking a general solution. Here is an example i found with trial and error:

Where the green signal is the input and the red signal is the response of a high Q bandpass filter
the signal is a 250Hz pulse with 5 cycles.
if we apply a 1 kHz for 2 cycles at 22ms we have,

Observe that the transient response is immediatelly suppressed

I would be glad if you propose a method to find a
\$
v_{s2}(t)
 \$
preferably a square one.


texts:
When designing a voltage doubler at RF frequencies...

Should you pick Capacitor values that makes C1 and C2 impedance 50 ohms ?


texts:
Solving transistor circuits is becoming very confusing. Is there a model for every topology? For example, I do not quite understand this answer:

I thought \$I_{E}\$ and \$I_{C}\$ were almost equal so why is it that when you divide \$V_{CC}\$ with both \$R_{E}\$ and \$R_{C}\$ you get different values? Also why don't we use the \$V_{S}\$ to find \$I_{B}\$ then later find \$I_{C}\$. Doesn't the \$I_{E}\$ value depend on the \$R_{C}\$. Where is someone supposed to start when solving transistor circuits?


texts:
I've had an idea of using LiFePO4 battery as replacement for car battery, since 4 of those in series make nominal 12.8V which is very close to standard 12V voltage. And depending on the cell we can parallel some to get required starting current. Since LiFePO4 have much longer life then Lead-Acid, such battery should last much longer.

But there comes few problems:

Charging voltage. Since most alternators produce around 14V volts when charging it should be fine with LiFePO4 battery since maximum voltage for those is 3.6V which gives us little headroom up to 14.4V (4*3.6V=14.4V). Individual cell balancing can be done with simple dissipative BMS which dumps excessive charge to resistor. But we don't have possibility to disconnect alternator when battery is charged, so here is first Question: is it OK to hold LiFePO4 battery at floating charge with voltage which is close to maximum battery voltage?  Or this will significantly decrease battery life?
Charging current. Some LiFePO4 cells can be configured so they can easily take all charge current produced by alternator. (assuming 70A output and 3 parallel 40152S cells) So second question: Can it overload alternator or modern alternators are smart enough to lower voltage to avoid being overloaded?
No over discharge protection. Currently have no idea how to deal with it besides not letting it to discharge completely.


texts: How Does A USB (non-PD) device modify the current it draws from a charger?

texts:
I understand at a basic level that a USB DCP simply advertises that it is a DCP, and then basically puts 5V on Vbus, and then the battery can go to town.

With that in mind this is really a 2 part question:

How does a battery limit it’s current to the 1.5A specified by the USB BC 1.2 spec? Take the example of a charger capable of outputting 2A, advertising as a DCP. Assuming the device being charged is compliant with the spec, how does it limit the current draw to 1.5A given there is no communication between the two devices? Does it modulate some sort of load switch? Does it even limit in the first place?
Are USB portable devices responsible for implementing the typical lithium ion battery Constant-Current/Constant-Voltage charge cycle? If so, does it taper the current by some method described in (1)? Or perhaps it relies on the increasing impedance of the battery as it becomes more fully charged? Perhaps it doesn’t implement a CC/CV charge cycle at all?

I appreciate any feedback on this. It seems like the answer should be fairly straightforward, but it’s been bugging me for a couple days.

Thanks!


texts: Which MPLAB-X version supports Pickit 2?

texts:
I got myself a Microchip Pickit-2 Programmer from a local store. I installed MPLAB release v2.26 from Microchip's website.

However, in this version of MPLAB, it is not detecting my Pickit-2. Hovering over the "Tools" field of MPLAB window indeed reveals that Pickit-2 is not supported, as shown in the attached screen-shot.

I want to ask which version of MPLAB supports Pickit 2? Or, does MPLAB even support it? Should I go for some other software?

FYI, I am running this on Linux.


texts: Can an isolation amplifier be used to block common mode noises and capacitive coupling?

texts:
A single-ended earth grounded data acquisition board have some channels fixed inputs as transducers. But when I connected extra channels as any of force transducer amplifiers, this causes standard deviation increase and some 50Hz noise in fixed channels and in the force transducer themselves as well. I already checked couldn't find any ground loop since the sources' DC grounds are not earth grounded.

But when I disconnect the force transducers the noise disappears and standard deviation decreases dramatically which is good. I notice that the force transducers have 78V common mode voltage which is a ghost voltage due to parasitic capacitance.

Im trapped because if I earth the DC supply of the force transducers I get rid of the common mode voltage but then this creates ground loops. But even I hook up the force transducer channel the noise comes back even though its earth is not grounded.

I was thinking to use an isolation amplifier at the end of each force transducer channel but that would require a lot of amplifiers.´

The force amplifier system with many cables shares the same ground and possibly corrupting the ground when hooked up to the daq because it is single ended(?)

Can an isolation amplifier be used to block common mode noises and capacitive coupling from the DC supply?


texts: Metal-oxide film resistors and power applications

texts:
I am currently studying The Art of Electronics, third edition, by Horowitz and Hill. Appendix C.4 Resistor types says the following:

For power applications you usually use wirewound resistors, either in an air-cooled ceramic package or a conduction-cooled (“Dale-type”) metal package. High-value resistors (\$>10 \ \text{M} \Omega \$, say) are usually of metal-oxide construction (e.g., Ohmite “Mini-Mox” or “Super Mox,” or  Vishay RNX-series). Film resistors are not tolerant of high peak power; for such applications use something like ceramic or carbon composition, or other styles specified for peak-power use.

In researching this, I encountered this page, which says the following:

Metal-oxide film resistors are fixed form, axial resistors.  They are made of ceramic rod that is coated with a thin film of metal oxides, such as tin oxide. Metal oxide film resistors must not be confused with metal oxide varistors, made of zinc oxide or silicon carbide.

So the textbook says that, for power applications, resistors of metal-oxide construction are suitable, and that film resistors are unsuitable because they are not tolerant of high peak power. But the website seems to imply that metal-oxide resistors are (thin-)film resistors. Maybe I'm misinterpreting the authors, but the part that says "high-value resistors (\$>10 \ \text{M} \Omega \$, say) are usually of metal-oxide construction" seems to be implying that they are used for the aforementioned "power applications" in the previous sentence, no? How do I reconcile what these two sources are saying?
I would greatly appreciate it if people would please take the time to clarify this.


texts: What is the role of DE input of ADV7511 HDMI video controller?

texts:
I need to understand the data, DE, VSYNC, HSYNC and CLK inputs of ADV7511 video controller. I need them to program FPGA card (Xilinx Kintex KCU116) that has this video chip. FPGA manual says it uses ADV7511 to provide 1080P 60 Hz, YCbCr 4:2:2 encoding via 18-bit input data mapping.

The 18 bit data bus looks more or less clear, VSYNC and HSYNC most likely mark end of the frame and end of the row, and CLK is for the clock, hopefully one tick per pixel. Please correct me if these assumptions are wrong.

What is the DE signal for? Can I leave it maybe unconnected? I have looked into various documents on the product website, but seems that the signals are not properly described. The FPGA board manual does not explain much either.

There is another question about ADV7511 but it is different and looks way too broad to be answered.


texts: Stepper motor power supply causing large ripple

texts:
I currently am rebuilding a machine that uses 3 large 24V stepper motors, running at 1A per phase.

The machines' original transformer has a 10V and 28V output, and I have tried limiting the 28V output to 24V, with varying degrees of success.

Below is the current design for powering the motors (the 6A load is the maximum power draw)

  Ninja edit - The IGNOREME resistor changes the regulator to a 24V regulator (originally 15V)

Simulating the circuit, at 1A load gives a ripple of about 3V, but at 6A it gives up to 14V ripple. (With or without the regulator part)

I recently did read on a different website that large stepper motors can handle up to 35V before you need to worry about power considerations, but we don't have replacement motors, but the forum didn't have many replies, and a few of them contradicted the main post. (https://forum.arduino.cc/index.php?topic=462832.0)

I am asking for ideas of reducing the ripple further, and if the regulator circuit is unneeded.

Thanks for your time.


texts: Why backlight an LCD display with AMOLED? Can IPS terminology apply to AMOLED?

texts:
I've been reading about IPS LCD and LED/OLED display technology in general, and am a bit confused about the following product:

HP Spectre x360 2-in-1 Laptop: 15.6" 4K, i7-8705G, 16GB DDR4, 512 SSD, Vega M GL

In the specs it says:

15.6" diagonal 4K IPS anti-glare micro-edge AMOLED-backlit (3840 x 2160)

What actually is this?

Based on reading the wikipedia articles on IPS and AMOLED I have two ideas:
 1. That they are backlighting an IPS LCD screen with AMOLED.
 2. That they are using the IPS terminology to refer to the active matrix part of the OLED.

As for hypothesis (1) Why would you do this though? Isn't the point of the the AMOLED that the OLED is managed by pixel addressing with an active matrix? What benefit do you get from mixing the two technologies in the same screen?

As for hypothesis (2), I see an enormous number of articles arguing for AMOLED or IPS being better technologies, so could they be marketing this as a hybrid so that buyers say "this has both!". Since AMOLED stands for active matrix OLED and IPS is technically an active matrix, could it be that HP or Samsung is using the term to describe the thin film transistor matrix that addresses the OLEDs. Am I overthinking this?

What actually is going on with this product?


texts:
If I wound 2 solenoids with current in opposite direction (wound into each other like in the 1st photo) will I cancel the magnetic field ? Or did I made it stronger ?

Is it better having a twister pair cables, with current in opposite direction?
Or is it better to have 2 solenoid wound in opposite direction?
Which one gives the lower emf to nearby components (the best emf cancelling effect) ?

Thank you.

(I run the wires with 9VAC 2A psu)

EDIT : Clarifications : In the green wire I have -4.5V and in the red I have +4.5V. The current flow in different directions. The cables feed a load. The green wire is the current return path (conventional).


texts:
I have the electricity meter pictured.

When I attach various devices I get readings (amps, volts, watts) that are proportional. Expected values are a few percentage points off from the readings.

For example an ethernet switch with a pair of servers on standby: 0.865A, 121.2V, 97.4W versus an expected 104.8W, which represents a 7% difference compared to the midpoint.

A pair of servers on standby gives worse results. 0.291A, 121.9V, 25.6W. The wattage is compared to an expected 35.5W which represents a 32% difference compared to the midpoint.

When I attach a 22 inch LCD monitor I get readings of 0.478A, 120.9V, and 36.7W. Note that I*E = 57.8W and P/I = 76V and P/E = 0.3A. The expected wattage represents a 45% difference compared to the midpoint. These results are worse yet.

The label on the monitor says 100V-240V 50/60Hz 1.5A.

Why would the meter produce such readings?


texts:
I'm new to Cortex M4 and programming on a microcontroller. I'm still learning the basics.

I'm using this board (stm32f411re), here is the reference manual.

I am trying to make an interrupt on the press of a button (the user button which is connected to the "PC13" port (pin 2)). First, I'm trying to initialize the button so when I click it, it will fire one exception.

Here is my code :

void button_init(void)
{
    <======== PART THAT I'M TRYING TO UNDERSTAND ========>

    // Enable GPIOC clock because BUTTON is connected to GPIOC
    RCC->AHB1ENR |= 0x04; // (page 114)

    // Configure the mode
    GPIOC->MODER &= ~0x3; // GPIO port mode register (page 153)
    GPIOC->PUPDR  &= ~0x3; // GPIO port pull-up/pull-down register (page 156)

    <======== PART THAT I'M TRYING TO UNDERSTAND ========>

    //System configuration controller clock enable (page 118)
    RCC->APB2ENR |= 0x00004000;

    SYSCFG->EXTICR[3] |= (0x02 << 4); // (page 139)

    //configure the interrupt for exti 13 line
    // EXTI->IMR |= (0x01 << 13)// enable interrupt on EXTI 13
    EXTI->IMR |= 0x01;
    // EXTI->RTSR |= 0X01;
    // EXTI->FTSR |= (0X01 << 13) // sensitive to falling edge
    EXTI->FTSR |= 0X01;

    //nvic configuration
    NVIC->IP[EXTI15_10_IRQn] = 0x00;
    NVIC_EnableIRQ(EXTI15_10_IRQn); // EXTI15_10_IRQn must be 40.. please confirm
}

Here are my questions :

Am I right with this calculation ~0x3 = ~(0000 0011) = 1111 1100 ?

So when I do GPIOC->MODER &= ~0x3;, am I setting the first to bits of this register to 00 (input mode)?

Should I set other two bits of this register ? How can I know wich two bits of this register are linked with my button ?

Same questions with GPIOC->PUPDR  &= ~0x3;

Finally, I want to enable a clock so I do RCC->APB2ENR |= 0x00004000; : 0x00004000 = 0100 0000 0000 0000 => I set the 16th bit of this register which is "TIM9 clock enable". Is that what we want to do ? Why TIM9 and not TIM10 or TIM11 ?

Thank you very much!


texts: Cleaning up 4.8V and 10.8V DC power affected by spark ignition system

texts:
I am developing an autonomous heli drone, powered by a petrol engine. Servos and radio receiver use power from a nominal 4.8V NiMH battery pack.  Autopilot takes power from a nominal 10.8V NiMH battery pack. (These battery packs with full charge are typically 5.3 -5.5V and 11.7-12.0V)

Petrol engine ignition system is magneto. The low voltage coil produces +/- 150V, this is fed to the high voltage coil connected to the spark plug.  When engine is running, electrical noise is present on the airframe, and measurement of the power to the servos and autopilot shows voltage spikes of up to 500mV.  This adversely affects the flight electronics.

Ideally, I would like to prevent the ignition system from affecting the other aircraft systems, but  cannot find anything on the web regarding suppression of the low voltage side of the magneto ignition.  I have tried suppression of the high voltage side using additional resistance in the form of a 5K resistance plug cap - this did not significantly change the noise being induced elsewhere. This makes me suspect the low voltage side.

If I cannot eliminate the source of the noise, then as an alternative I need to clean up both power supplies, using some type of regulation/stabilization immediately upstream of the flight electronics.

Any suggestions?


texts: How do I make my electrical enclosure waterproof, what type of connectors I use?

texts:
We are designing this meter which will monitor house hold consumption. The problem that I am facing right now for days and weeks now, how do I make the meter water proof. I have tried everything but could not find an exact solution.

I tried looked for already made enclosure box that we can  use they are a bit expensive as we need bigger enclosure (>240mm) + I dont know who the whole can be air tight when we passing electrical wire through it.

We are also exploring molding option but I dont know what exactly I need. For do I place conducting strips in the mould already which will be my connection point from inside and outside? Or do I drill holes in it and later cover it with some special connectors. Any help is appreciated.

I cam across these types of enclosure (highlighting the joint), should I be  using something similar. How do they provide water proofing. What is recommended technique to create water and dust proof isolation for a meter?

Included is my meter design where I need help regarding water proofing.


texts:
I am looking into designing a data converter that must provide data from a Scale (usually referred to as an indicator) to a very old PLC that only accepts data in BCD.

The current device that does this is failing and is no longer available (for quite some time now).

BCD isn't the problem, but rather the current device outputs the BCD in TTL to a 50 pin connector. The 50 pins include 6 digits worth of BCD digits along with a Gate signal for each digit and three inputs to the BCD source. (see inputs on pins 37, 39, and 50).

Schematics are of course not available of the current device while those for PLC inputs can be found, but only 'examples'.

Question:
Does anyone have experience with a PLC "and" BCD inputs such that you can tell me that the BCD data is "loaded" when one of the inputs to the source of the BCD data (pins 37, 39, or 50) is asserted?

Elaborating on the question:
The BCD data is presented in a parallel fashion via the 50 pin connector. I do not have physical access to the current (failing) hardware. (it is 450 miles away. If I did I wouldn't be asking this question.)

In order for me to provide the data to the PLC per the 50 pin data cable I need to know if (again when dealing with BCD data) the PLC asserts one or more of the signals I mentioned (pins 37, 39, or 50) to "latch in" the data. I would imagine that (or something) is used to sync when the PLC "reads" the data in.

This is going to be an "old timers" type of question, this system was installed in 1981.

Thanks!


texts: My third hand damages wires insulation because it's holding them too tight. Any tips how to avoid this?


texts:
I know I have got a trivial question but I can't find a proper explanation on the internet. In the image below I know that the formula for the cutoff frequency is f = 1/(2*PI*(R1//R2)*C).
One way to get the above formula is to find parallel impedance of R2 and C1. Then apply a voltage divider formula for R1 and R2//C1 and then we can derive the cutoff frequency.
But I was wondering is there a better way to get this formula by finding
the equivalent resistance of R1 and R2 first and then substituting this equivalent resistance into simple RC filter formula? Is there any method that would allow me to calculate the equivalent resistnce  of R1 and R2 first and then use standard RC filter formula? Thanks in advance


texts: What does the plus (+) mean in a voltage source symbol?

texts:
Does the plus in voltage source symbol represent the highest potential end or does it represent the positive end?

Is that answer true for IEEE and IEC and NEC?

It may seem trivial for those who know but I did my research and did not find the answer.

UPDATE:

My question arises due to the fact that there is electron flow (the real one when electrons are the charge carriers) and convention flow (the adapted one to avoid thinking "negatively" twice).

If the plus means the positive end, then electrons are moving into that end in electron flow, since electrons will go from the negative end to the positive one.

If the plus means the highest potential end, then electrons are moving out of that end in electron flow, since electrons will go from high potential to low potential.


texts: Can I use a voltage divider for shifing logic levels?

texts:
I'm trying to drive a 3.3V IC from an Arduino which has 5V logic pins, so I need to shift that 5V down. There's no data from the 3.3V device to the Arduino so I don't need to shift back up.

Can I use a voltage divider to do this? My concern is that since the device is not a passive component (it's an ST7735 LCD driver), its effective resistance is not constant (right? As the transistors and whatnot in the IC switch, the overall resistance/current will change?) and so the voltage "output" from the divider will change.

That is, in this picture:

R2 is not constant and so Vout may vary.

Since Sparkfun's logic level converter uses a voltage divider for down-shift, I suspect that this is fine, but I don't understand why.

(This is my first electronics project. I would usually just use Sparkfun's LLC but I'm in a country where it's not so easy to buy electronics from America!)

I should clarify that I'm not using this 3.3V to drive the LCD itself (I think). The breakout has a separate VCC pin, which I'm connecting to a 3.3V supply which the Arduino provides. It's just the logic pins I want to shift.


texts:
I want to make one of those circuits
using an old PNP germanium transistor (2SB175)
what values of resistors should I chose and which circuit is good ? , if the circuits are bad, is there any better arc generator (hv) circuit using this transistor (2SB175) ?

Could anyone please help me.
Thanks


texts: Is using a wire rated the same as its circuit's fuse OK?

texts:
I want to add a kill switch on the fuel pump relay in my car, which includes extending a line connected to a 15A fuse.
I bought some 15A auto wire, but on reflection I'm not 100% sure if that's right. Since the wire is rated the same as the fuse, is there a chance it will melt instead of/at the same time as the fuse in the event of an overload, or am I overthinking it?


texts:
I'm a bit confused about the resolution of a potentiometer as a voltage divider.

What's the relation between voltage and number of turns in a pot?

For example In below circuit:

What the resolution of the multi-turn potentiometer would be if we increase/decrease the 5V?
Assuming it's a 10 turn pot, to calculate each turn we should divide that 5V to 10,000?
Does adding gain to the op amp will reduce the resolution of the pot even more? is there anyway to compensate for that?

simulate this circuit – Schematic created using CircuitLab


texts: What type of relay/switch device am I looking for?

texts:
I want to control a 24V primary device based on a digital signal from a secondary device.
The secondary device emits a periodic pulse when I want the primary device to be ON and no periodic pulse is present when I want the primary device to be off.
I assume I need some type of relay, but I don't want the relay to turn ON & OFF with every pulse...I just want the relay to activate when the pulse is detected and remain active until the pulsing stops.
(I'm hoping to buy the pre-built switching device online, but I don't know what this type of switching system is called?)


texts: Difference between zero-drift and auto-zero op amps?

texts:
I am in the process of choosing an op amp for a DAC output buffer. To me, choosing an op amp with the least voltage offset seems like the best choice, naturally leading me to look at zero-drift and auto-zero op amps.

On Digikey, there are three options: zero-drift, zero-drift (chopper) and auto-zero. I understand that the second one is just a kind of zero-drift op amp, but what is the difference (or are they the same) between zero-drift and auto-zero? To my knowledge, both include a method of compensating for offset voltage.

Googling the question leads to results that only mention that zero-drift and auto-zero op amps are the same (usually "zero-drift(auto-zero) op amps...") but offer to explanation as to how they are the same, or any differences.

Can anyone shed some light on this for me?


texts:
I am troubleshooting a servo motor that is running while the brake is on when it shouldn't be. I have traced the control circuit for the brake as far back as made sense to. The brake is on a Panasonic motor and should be just an inductor - when 24V is applied the brake turns off, so it is used on a Z-axis to have a brake in case of power failure so a robot arm doesn't fall.

[![

simulate this circuit – Schematic created using CircuitLab

][1]][1]

When I test the voltage on the connector that goes to the brake it has 24V until I connect the brake, then it shows 0V. I know that at constant current an inductor won't have a voltage drop across it but I thought that was only for ideal inductors - mine has ~90ohms resistance. The brake also doesn't actuate from the control circuit but if I hook up a 24VDC power supply to it it works to turn the brake off.

I am wondering what could be causing this and if it is something in the circuit controlling the brake. The brake is controlled by a PhotoMOS, http://www.mouser.com/ds/2/316/semi_eng_gu1a_aqv21_s-850760-932955.pdf

I've attached a drawing of the schematic and a simulation circuit just for testing (the sim circuit doesn't have the same components as the original) - and the simulation worked as expected, giving voltage across the inductor when the opto was conducting but none when it wasn't.

I would appreciate any help or advice


texts: What could be the reason for chip capacitor failure due to silicone potting?

texts:
Is silicone potting of PCB board beneficial or risky?

What could be the best material for encapsulating a power supply board?

I used 2 part mixed silicone potting compound for encapsulating a microcontroller based (ASIC based, too) power supply, and one of the chip capacitors on the board failed within few hours of regression of device.

Reason is still unknown, looking for some valuable suggestion.


texts: Oscillator circuit based on a SAW delay line

texts:
I was hoping someone may be able to point me in the right direction for a oscillator circuit that depends on a SAW delay line for control of the frequency.

The SAW central frequency is 20 MHz, for information, and it seems some characterisation of these devices are better performed in frequency, and I've read about oscillator circuits used for these purposes.
I would like to get an idea of the setup necessary and happening within it.

Any help, advice or pointing to resources would be appreciated.


texts: Why microstripline is compulsory to generate high frequency signal in the range of 2 Ghz or more

texts:
I would like to understand why the UHF (Ultra High Frequency) band in the range of 1 Ghz or more like 2.4 Ghz or 2.6 Ghz require microstripline to generate such signal frequency?

Is there any alternative that we can use that is readily available without microstripline?


texts: How to charge a 48V battery (12V battery * 4 in series connection) with a 12V charger?

texts:
I found a question about charging the battery with a 12 volt charger. However I’m confused as to do this?

First method, unhooking and charging each battery individually?
But wouldn’t I be just shorting a battery out if I tried charging one at a time while they are still wired in series.
Would charging the whole series only yield a 12 volt charge on the series? I was thinking of just buying a proper 48 volt charger

Charge 48V battery bank with 12V.


texts: Help with my H-bridge circuit using MOSFET

texts:
I had a problem with making H-bridge to drive 32V 6A Motor

voltage control is 12V

input: IN1/IN2

whenever i tried to test it the Amp goes up in the 32V motor power "it becomes short circuit"

if you need more information let me know thanks.


texts: How can a switch that is in parallel with a lamp affect the lamp?

texts:
I've come across a faulty kiln (pottery oven) and since the wiring diagram seemed simple enough I decided to try to find the fault myself. However I'm dumbstruck by a strange behavior of a lamp.

The oven is a powered by three phase power (but only use two phases, as evident in the diagram.) The two heating elements are controlled by a digital controller (the box to the right in the diagram) with a 7-pin connector. The controller has a switch that breaks the power (the L1 line) to the controller itself.

Looking at this diagram, it seems obvious to me that the lamp should light up whenever you connect the oven to the power outlet (given that the fuse "F0" is intact of course, which it is.) I mean, the lamp is in parallell with the controller so the voltage across it should be constant. However, in reality the lamp behaves like this:

When the controller is disconnected, the lamp only flickers very dimly.
When the controller is connected, and the switch is closed, the lamp lights up at full power. When the switch is open, the lamp is off completely.

What is going on here, shouldn't the voltage across the lamp be constant?


texts:
My attempt:
I first converted the delta network into a wye network.
The 4 ohm and 2.69 ohm resistors are in series, that series equivalent is series with the 0.38 ohm and 0.54 ohm resistors. The 3 ohm and 2 ohm resistors are also in series. Finally the 8 ohm and 6 ohm resistor are parallel. Is there an easier way in which I could reduce the circuit keeping the 7 Ohm resistor? If I were to leave the delta network without performing any simplification on it, how can I go about solving this problem?


texts:
I'm trying to make an IR visible object tracking device.
Is there any way to convert visible machine vision camera to an IR vision camera
datasheet link:
https://wiki.dfrobot.com/HUSKYLENS_V1.0_SKU_SEN0305_SEN0336


texts: Arduino moisture sensor value decreasing for no reason

texts:
I'm not sure what happened but all of a suden the moisture sensor I bought is acting strange. When I place it in soil and measure the value once per second, it decreases in value pretty quickly about 3 points downwards every 5 seconds.

When I am holding the sensor in the air, it reads 1023. When I put it in water, it reads around 400. When I place it in soil, it starts at about 700 and then starts decreasing, meaning it is getting wetter. How can that be possible if I didn't water the soil? Something is happening with it.

EDIT: Upon just jiggling the wires that connect the moisture sensor to the arduino...the values jumped down about 50 points. Jiggling more makes it jump around more. Is that normal?


texts: Driving ULN2064 with 74HC595 for 12V motor loads

texts:
I've made a circuit with ( Arduino + 74HC595 + ULN2803 ) to drive 20 hobby motors using 12V 10A Supply.

Initially It Looks Good, But when i started running one motor,

Motor running too slowly and sometime not running
Voltage getting down to 1.2 V from 12 V
ULN2803 Heating Up
Even few channels damaged

I found that motor drawing more current, then i stacked TWO ULN2803s with NO use.

After some search i found ULN2064B comes with 1.5 A Per channel output.

Question : How can i drive ULN2064B with 74HC595 or similar ???

Expecting circuits, explanations As i'm not proficient in electronics.


texts: How can I build my own wireless charger for my cellphone?

texts:
I am designing a wireless charger for my cellphone, Where my Primary coil is energised with 1.5V and 0.3A, Where I have used a transistor to turn it on and off at a frequency of 1Mhz.
In the secondary coil I got a peak to peak voltage of 32V and Vavg of 0.8V, Which I later rectified using a resistor and capacitor in parallel and I achieved a Vavg of 5.8V and the current in Microamps.

Since the current was insufficient to charge my cellphone,How can i improve the current in secondary Coil.
Note: My primary coil had 40 turns
Secondary coil had 20 turns.

The distance between primary and secondary coil is less than 1cm

simulate this circuit – Schematic created using CircuitLab


texts: Why do electrons move faster than holes in a semiconductor?

texts:
When an electron leaves, then only a hole is created, and when another electron fills it, then only the hole moves, so in that way, both should conduct current at the same speed.  Yet I've been told that holes have higher mobility than electrons.
Please explain how that can be, I'm confused.


texts: A sensor which can measure the vibration of a material

texts: I am planning on making a musical instrument where I require the conversion of vibration of a material to voltage. The idea is to make a percussion instrument where I hit a plate made of a certain type of material. Based on the different areas on which I hit the plate, the vibrations will be different and after converting the vibrations to voltage, I will take the FFT of the signals to differentiate the different areas on which I hit the material and map it to produce a particular sound. I know that piezoelectric sensor is a material which converts pressure to voltage but I am not sure if it will be robust enough. Is there any alternative I can use?


texts: Why are delays required in verilog with combinational logic?

texts:
I have been getting into FPGA programming and Verilog and have been playing around in EDA playground for a bit creating some simple stuff. Often I need a clock so what I do is generate one on the testbench side using:

for (i = 0; i < 1000; i = i+1)
begin
    #10 clk = 1;
    #10 clk = 0;
end

Which works well. Problem is that if I remove the #10, it doesn't work. And I can't figure out why.
The reason I'd expect it to work if I remove the #10 statements is because if I am correct, = is blocking in Verilog. (Where <= is not) So to me, it would sound like it should generate a signal as fast as it can. But if I try it in EDA playground, no signals are generated at all. (The signal inspector would just be completely empty)

Does anyone know why?

Thanks!


texts:
I'm currently working with raspberry pi's that are going to be powered through an LED night light (its for being able to observe people working on experiments and giving light to the camera) and in the light itself it uses a 7 voltage supply - there is no LED in the light but instead using the power that would supply the LED to power the pi.

The raspberry pi uses 5 volts and in the light itself there is only a positive and negative cable. I really don't want to open up the power supply itself though.

I have looked into using a voltage regulator but the problem I find is it needs positive, negative and earth.
Is there anything I can use to bring down the voltage down to 5V without an earth?

Thank you

This is the lamp that we intend to use
inside where the lamp bit is there only exists a positive and negative cable. There is no earth.

Here is the power supply we are planning to use:

Edit We have decided to go for official raspberry pi switches.

Thank you for your help


texts:
An inductor is a device which adjusts its voltage to keep the same current flowing through. However, the current exponentially decays when there is no source any more. Similarly, a capacitor is a device which keeps the voltage across itself constant. However when charged, the voltage exponentially decays when a load is connected. THe building block of a buck convertor seems to be the L and C. However I am having a hard time understading how an LC circuit actually operates(in a buck). I understand that the capacitor is kind of a snubber capacitor to allow current to flow through and provide a path when the high side PMOS is turned on. However, that job could as well have been done by an resistor, given that Voltage mode control is being used. The only advantage I see to using a capacitor is the efficiency, since energy is not wasted. I applied a current step to my inductor in LTSPICE and this is what I got:

I understand that initially, the voltage at the left hand side of the inductor should actually try to become 0 to allow no current to pass(the initial state). However this doesnt seem to be the case. Can someone explain intuitvely what exactly is going on in the LC circuit. How should it be analyzed?


texts:
I am searching for process node data sheets. Specifically, I'm interested in TSMC's 16nm, 12nm, 10nm, 7nm nodes, as well as Samsung's 14nm, 10nm nodes. I did not find anything with Google.

How can I access process node data sheets?


texts: How to calculate and power supply multiple led strips

texts:
Months ago I bought 3 RGB led strip (1 meter, 60 leds) and now I want to use it on a project.
The specification said

DC5V
18W/m

I struggle with the power supply and the type of circuit I need for this, series vs parallel. If I choose series circuit :

3 * 5V = 15V
3*18W = 54W and then 54/15 =  3.6A

I found a laptop power supply with 15V and 4A, how can use it with my circuit ?
With parallel circuit :

5V
3.6A * 3 = 10.8A

What is the best solution to connect the 3 strips together ?


texts: What are design considerations for grounding an enclosed AC-to-DC converter?

texts:
Here I'm talking about a device that takes 100-240V AC in, and outputs 10-20V DC out. In terms of grounding, I'm referring to the grounding offered by a standard outlet (e.g., a NEMA-5-15R receptacle). In this space, many devices have a grounded (three prong) cable and many don't.

I'm particularly interested in say laptop power warts (AC-to-DC converters, which are generally always external to the device). The older laptops I had used two-prong ungrounded plugs. The two most recent laptops, however (one Mac, one Dell) have both used grounded plugs.  This is really annoying when traveling as many adapters and even outlets don't support the ground plug.

Adding to the confusion, it seems that the same transformer, for the same model laptop, comes with a two prong plug in other countries: my Dell has a detachable power cord, and I've an otherwise identical brick for the same laptop sold in another country with a different cord that omits the grounding plug.

In all cases, the AD-DC bricks are fully plastic with no exposed metal parts.

When designing such a device, what are the considerations that would cause a fully enclosed plastic line lump for something like a laptop have a grounding prong?


texts:
I'm a beginner in STM32F4 and I'm learning how to use the USB Virtual COM Port ("VCP") to transmit data from the microcontroller to a PC.

The virtual port is detected as "STMicroelectronics Virtual COM Port", and I use serial monitoring software to see the data received by the PC.

The PC is receiving all 0x00 no matter what I send in my code.

I called VCP_DataTx() function to send data.

Any ideas about what's wrong?

p.s. in my main() function, I only called USBD_Init() to initialize USB Device, is that enough? Did I miss anything that should be configured? I see someone say USART when talk about VCP, is there any relationship between them?

Thanks.

This is my main.cpp. I did nothing more but initialize USB device and send data.

#include "usbd_cdc_core.h"
#include "usbd_usr.h"
#include "usb_conf.h"
#include "usbd_desc.h"

#include "usbd_cdc_vcp.h"

USB_OTG_CORE_HANDLE    USB_OTG_dev;
uint8_t Buf[6] = "A";

int main(void)
{
  __IO uint32_t i = 0;

  USBD_Init(&USB_OTG_dev,
            USB_OTG_FS_CORE_ID,
            &USR_desc,
            &USBD_CDC_cb,
            &USR_cb);

    VCP_DataTx(Buf, 6);

  /* Main loop */
  while (1)
  {
      VCP_DataTx(Buf, 6);
      while (i < 0x77ffff)
      {
          i++;
      }
  }
}

In order to call VCP_DataTx() in main, I deleted static keyword in usbd_cdc_vcp.h and usbd_cdc.vcp.c

p.p.s. I didn't realize usbd_cdc_vcp.c is not in STM USB library. It comes from the VCP example in STM32_USB-Host-Device_Lib_V2.1.0, and the function VCP_DataTx() looks like:

uint16_t VCP_DataTx (uint8_t* Buf, uint32_t Len)
{
  if (linecoding.datatype == 7)
  {
    APP_Rx_Buffer[APP_Rx_ptr_in] = USART_ReceiveData(EVAL_COM1) & 0x7F;
  }
  else if (linecoding.datatype == 8)
  {
    APP_Rx_Buffer[APP_Rx_ptr_in] = USART_ReceiveData(EVAL_COM1);
  }

  APP_Rx_ptr_in++;

  /* To avoid buffer overflow */
  if(APP_Rx_ptr_in == APP_RX_DATA_SIZE)
  {
    APP_Rx_ptr_in = 0;
  }

  return USBD_OK;
}


texts:
I am going to build a low voltage and low power Modular Multilevel Converter (MMC) for research purposes. In each phase of MMC, there are two inductors where low frequency (50 Hz) currents pass through. On the other hand, I need inductors with few miliHenry inductace that can tolerate low frequency currents of a few amps (e.g. 5A).
I am having hard time finding such inductors on digikey or RS or Farnell. The only one that I've found is this common-mode choke, but I am not sure if it can be used as an inductor for the mentioned application or not.
Any ideas?


texts: Can I set thresholds for 74HC14N (6 NOT gates)? and use as schmitt trigger

texts:
I'm trying to convert sine-like wave from IR sensor(quadrature wheel encoder) into square one. Can I make it with 74HC14N(set some fancy RC configuration) or should I use op-amp configuration to be able to set thresholds?

here Y is 5 volts scaled to 1024(arduino). So it's around 0.4-3.4 volts.

Here is another example and what I need to get

Or if you know DIY guides for quadrature wheel encoder that solves this issue, can you please share with me?

Thanks in advance.


texts: Voltage in a circuit with variable resistance and diode in series?

texts:
I came across some examples to calculate the current in a circuit with diode and resistance in series. Consider the circuit below:

Current was calculated as follows:
I = (9 - 0.7)/R1
Does that mean that no matter what the resistance R1 is, the voltage drop across it is always 9 - 0.7 Volts? Or in other words, diodes decide the drop across a resistor by varying current through it unlike how in a circuit with only resistors, increasing value of resistance also increased the voltage drop across it?
Also, if the above assumption is true (i.e. taking higher resistance will lower the current value in the circuit but the drop across diode is 0.7v only), but doesn't that violate the V-I graph of a diode where at a specific voltage, a specific current valule should be there while we see different values of current for same value of voltage drop (0.7v)? (based on assumption)


texts: Low cost method for retrieving information from a microcontroller

texts:
I am in need of a device that can poll and record the temperature of an area automatically such that I can get the information on to my computer somehow.

I am thinking of buying an NTE7225 temperature sensor or something similar, and hooking it up to a cheap microcontroller.

Where I am stuck is how to store the information so that I can retrieve it later.

I would need to store the information for days, preferably indefinitely until removed, but as long as it is powered on would be the next best one.  The amount of data would be minimal, one temperature reading and timestamp every n minutes.

The accuracy of the data would preferably be as accurate as the sensor is reporting (but that may be naive).

The only two methods I can think of would be to:

Buy an SDCard port of some sort and write an SDCard driver to put the information on to the card
Use a USB port that exposes itself as a mass storage device with a file on it with the information in it.  This has the added downside of being volatile.

Are there any other good ways to do this?  I can probably do it with a plug computer or raspberry pi, but I’d like to see if I can do it more minimally.


texts: How would you know the voltage of a motor with no label?

texts:
I found a motor.
Unfortunately the label has been removed.
How would I know what voltage it operates on?

It has 2 wires.
It has an attached square thing on it.
It's either 12 volts, 110 volts, or 220 volts, because that is the only voltage we have in the factory.


texts: Odd Ground/Power(?) issue with Mixing Desk - alternate grounding?

texts:
I am a bit stumped with this one. Unfortunately there are a few variables involved, but I will do my best to ask an answerable question....

I just built a DIY synthesizer. It functions absolutely fine. This is the pcb design:

http://www.midibox.org/dokuwiki/lib/exe/fetch.php?media=mb-6582:mb-6582_base_pcb_r2_color.pdf

plugged into a small guitar amplifier, it functions normally, and the on/off switch functions to disconnect power from the synthesizer.

However, when I plug it into my mixing desk, any audio lead attached to it disables the on/off power switch and the synth is always powered up. The synth continues to work properly, I just cannot disconnect the power with on/off.

I had the idea that this is occurring because it is somehow providing an alternate ground (because I don't believe it can be supplying a voltage, especially not one that would not have destroyed the synthesizer) when the ground is disconnected by the on/off switch.

With that in mind, I put a Ground Lift "hum remover" in between the synth and mixing desk. Sure enough, this solves the issue and the on/off switch operates again.

The mixing desk itself is connected to an audio interface as both input and output, plus several other synthesizers, and a microphone.

is there something obvious causing this that I am missing? I am a bit stumped as to what is happening (I would assume an error in the assembly of the synth, but the issue does not exist with other inputs!)


texts: Switching a line of batteries with MOSFETs

texts: I want to build up a small batterybank made of modules. The modules should be separated and in series as shown in the image. Is it possible to switch the total 48V if the MOSFETs are only connected to the last module and have only the ground potential of the batterypack they are connected to?


texts: Is it okay to keep a USB charger plugged into the cigar lighter?

texts:
I have a USB micro charging adapter for my smartphone for my car. It is basically a cigar lighter plug that turns into a USB micro plug. When I don’t have my phone connected, and as such don’t want the adapter to draw any current, is it still safe to keep the adapter plugged in?

I’m wondering because most other AC adapters (i.e. those not for the car) usually keep drawing some current, even if no device is connected. Is that also the case for those car adapters? Should I rather unplug it whenever I don’t need it?


texts: Making an Ethernet Shield work with an Arduino Mega

texts:
customer question:

I have had no success with the ethernet & saw some fine print

  Please note that the current design of the ethernet shield is not compatible with the Arduino Mega http://arduino.cc/en/Main/ArduinoEthernetShield

Is that correct? Is there a workaround?


texts: Solder Pad and Stencil Mask Data Sheet - Confused

texts:
I am using Autodesk Eagle. Need to create a footprint for CREE LED XHBAWT which is in the XLAMP XH-B series.
I do not understand the Datasheet drawing of the footprint, attached.

Are the lower views rotated 90 deg from the upper views? If so that seems odd.
Why is there the horizontal gap on the stencil mask on the right, but not on the solder pad on the left?
What are the little "tabs" on the Solder pad drawing?
Do I need the Solder Pad drawing?  Don't I just use the Stencil Mask Drawing for my pads?


texts: How to reverse a 240 single phase 7.5 hp motor

texts:
Trying to use a WEG 240 Volt electric motor from a IR compressor to power a different compressor pump. The electric motor is wired for CW rotation and I need CCW. The motor has 2 Start Capacitors in series and 1 Run Capacitor. Looking inside the motor there are 4 wires coming off the windings but I am not sure if its possible to reverse the rotation. Can't figure out how to change the polarity on Starting Winding.

Thank You


texts: Multiplexing problem with Arduino, MAX7219 e BJT

texts:
I tested the circuit below with an Arduino UNO, a MAX7219 and BC338. The sketch in Arduino is a chaser, so the leds should turn on in sequence. It consist of 7 segment (A-G) and two Digit (0-1).

The problem is that when one segment is turned on (and only that led sould be), also the same segment on the other digit is turned on. The problem si showed in the image below.

I tried with pull-up resistor and other tests, but I don't know what's the problem. Thank you for your help.


texts: Does anybody know if usb super speed enumeration needs the low speed D+/D- lines?  I know in HS it first negotiates over low speed then chirps to get to HS mode.  However I saw an intel design where they only used the SS lines to connect to a device.  Reading the USB spec and then googling up some docs on USB 3.0 enumeration didn't really make it clear.


texts: For an ideal Capacitor, when is the current leading and when is the voltage leading by 90?

texts:
Say I have a purely restive load as a reference in parrallel with an ideal capacitive load. I know that the current through the capacitor is said to be leading by 90 degrees. Specifically though, what is it leading?
With the two loads (resisitve and capacitive) in parrallel with the power source, can we say that the voltage will be the same both in magnitude AND phase across both components? AKA Vsource = Vresistor = Vcapacitor.

I want to say: when in parrallel, the currents of the two components different and the voltage is the same. Likewise, in series, the voltages will be different and the currents will be different. Is this correct? Thanks!


texts:
Odd question. I have a rack of equipment that I would like to have a dedicated front panel switchable power... switch. Multiple switches on the front panel to turn off equipment individually. There’s tons of them out there. What I’m looking for is one that has multiple, maybe just 2, power inputs from the main UPS to the switch. I have one piece of equipment that at max rating would require a little over 10 amps, the front panel switch I’m looking at has a 15 amp max, with the other 4 pieces of equipment plugged in I will be pushing that 15amp threshold. Now all of this is based off of max power usage, but with the cost of the equipment, I don’t want to push it. Any suggestions? I don’t really want to have 2 switch buses, or UPS’s, if there nothing out there like this, I’ll probably just have the higher power device plugged into the UPS directly.
I’m not even sure if this question is worth it! As the UPS probably only has 1, 15 amp circuit for the entire UPS, as there is only 1 plug! Also considering all of this will be running on 1 15amp circuit with other devices plugged in at other outlets. Boy the more I think about this the more I better run a dedicated circuit! But I’m not there yet. Just seeing what is out there and what an actual professional might suggest. Thank you!! All of that brings me back around to my question though, is there a two input front panel switch like is linked below, that has 2 circuits/plugs?
Below is my the “high power”required equipment that I’m going to be using and the switch I’d like to purchase. Thanks to whoever picks this one up!
Switch
https://www.amazon.com/gp/aw/d/B00KFZ98YO/ref=psdcmw_10967801_t2_B00006B834
48 port POE switch 500W
https://dl.ubnt.com/datasheets/edgemax/EdgeSwitch_DS.pdf
UPS
https://www.amazon.com/gp/aw/d/B000DZRY9C/ref=ox_sc_act_image_4?smid=A2Q1LRYTXHYQ2K&psc=1


texts: 90 degree phase shift and frequency mixing

texts:
I intend to generate a sine wave of 14 MHz frequency ( without using LC based oscillators such as hartley or colpitt). However I only have at my disposal an op amp with GBP 3 MHz. So I plan to generate first a 500 KHz wave ( using Wien bridge oscillator probably) and step it up subsequently using mixers.

Firstly, is there a better alternative to generate 14 MHz( again not using LC based oscillators) ?

Also, I require the 14 MHz wave to be phase shifted by 90 degrees. Again due to lack of components, I can only use the same op amp and realize an integrator or differentiator for phase shift.

Now here is the important question :

Are phase shifting and Mixing commutative ?

That is, can I first phase shift the 500 KHz wave and then subsequently mix it to increase frequency to 14 MHz or do I have to first mix and then apply shift at last ( which obviously I cant) ?

If they are, then what other things do I need to consider in this operation ?


texts:
I know that in motional emf V=Blv where B,l,and v are perpendicular to each other. When one of them isn't, then there would be no emf. What formula supports this?(mathematical evidence)
Can anyone help?


texts: Connecting two LED stripts with individual power sources to one MOSFET

texts:
I have two LED strips (IKEA's Ledberg white), each with their own 24V power supply and I want to make them dimmable with an Arduino.

I was wondering if it is safe to connect both of them (their negative pins) to a single MOSFET? Or do I need two MOSFETs? I've tried and it works, but I'm not sure if it is OK. If it is, would I need any protection (diode?) to prevent current from flowing from one supply into the other? I'm assuming I wont need that because the LEDs would do that.

Also, assuming each strip consumes 44mA at 24V, how much current and voltage would pass trough the MOSFET?


texts: How to configure an analog filter(s) to maximally smooth out a 100 Hz PWM signal from a LED controller

texts:
I have an RGB LED controller which controls the brightness using a 100 Hz PWM, seemingly without any built-in smoothing at all. (recorded it with a soundcard, and those pulses are 100 percent rectangular. :)

I want the resulting voltage coming to LEDs to be as flat as possible, using a custom built filter/simple scheme, which should not be too expensive (otherwise it makes more sense to buy a better controller in the first place).

The LEDs are going to be used for lighting, so the filter should be ready for pretty high power (~100W max).

How should I go about configuring such a filter? Should I use an RC or LC filter? Just one or a series of filters? How do I decide on the electronic properties of the elements (capacity, inductance, etc.)?

UPD: by "as flat as possible" I mean as close as a simple, cheap-ish filter system based on usual components is going to get me. A 99.99% flat line is NOT a requirement! Just a filter that will smooth it out as best it can.


texts: GPS antenna of a phone works even it is placed inside, but why its not working indoor

texts: Sounds blunder, but trying to figure out how. I have heard its best to have line of sight to sky for GPS receivers to work. But in phones it could be on back side or in the PCB itself (I guess). So how it is getting line of sight since there is obstructions which should be the LCD or the phone casing itself. Even its receiving. But its not working when we get into a room


texts: Power analysis using Synopsys Design Compiler

texts:
I am trying to generate power report using Synopsys DC compiler.

At first I have generated VCD file using Modelsim simulator, which I have converted to SAIF file using "vcd2saif" command.
Then I proceeded to analyze the power through DC compiler.

However, I am getting an warning " There are 1166 objects not found during annotation", and the combinational switching power is showing zero for my design.

What can be the error?

I believe the internal signals in the generated SAIF file from the MODELSIM does not match with the internal signals of the synthesized netlist. Do I have to perform postsynthesis simulation, but then how to link the design library file with MODELSIM.

Kindly guide in this regard.


texts:
I am automating my house using components like ESP8266, 220 to 5V converters, relays etc.

How big is the risk of a fire starting from a component malfunction and how can I mitigate this? What should contain my design in order to minimize this risk?

Is there a book or some documentation that I should read?


texts: Electromagnetic wave equation for GPS waves

texts:
Recently, I came across a source which stated the model of a GPS L1 wave was:

My question is, how was this equation derived?


texts:
I have a problem with a circuit and I couldn't figure it out why is this happening. This could be a silly mistake by me cause I'm not really an electronic expert. So after spending some days struggling with the circuit I decided to ask for help here.

I am using a 5V Arduino Pro Mini and a RFID Reader Module, RC522. Also, since the RC522 works with 3v3 power source and logic level, I used TXB0108, an 8-bit voltage level translator for the SPI communication between Arduino and the RC522. And as it's obvious, I needed a 3v3 to power up the RC522 and as a source for TXB0108. So I used a LF33CV.

Here is how I connected the parts:

However, it doesn't work. By working, I mean the entire functionality like setting an Arduino IO Pin to HIGH to light up a LED. But, I checked the voltage of different parts of the circuit using a multi-meter and everything seems to be normal.

The way that it works perfectly and I found it accidentally is to use another (and external) 3v3 source to power up the RC522. I connected a regulated 3.3 volts DC supply to the 3.3v pin on RC522 (first pin from right / power) and the ground the the circuit's ground.

Any Idea why is this happening? Why haven't it worked by the first circuit I explained?

Update:

Not working schematic (TOP) and working schematic (BOTTOM):


texts: How does PCIe switch handle Gen4 to Gen3?

texts:
I'm going to make a JBOD, the SATA HBA is 2X PCIe Gen3
and my new Mobo only support new PCIe Gen4 8x
I want to fully utilise a Gen4 8x to connect many 2x Gen3 HBAs, so I've found this Gen4 swich from microchip
28 Lanes model can use 8X Gen4 for upstream and 8 * 2x Gen3 downstream, my question is does PCIe switch in general or just this model design to bridge between different Gen(like Gen4 to Gen3) and the downstream 8 * 2x Gen3 can fully utilise the upstream 8x Gen4?
P.S My thinking is Gen4 = 2 * Gen3, so upstream and downstream are equal, so all the bandwidth should be utilised.


texts:
Modern CPUs today are commonly clocked in the 3-4 GHz range.  How fast can typical modern ASICs be clocked?

For example if I were building a commodity ASIC for something like a disk drive or network card, how fast could I clock that ASIC while still following the normal design flow from a foundry like TSMC?


texts: Reconciling V, A, iPF and kW for my air conditioner

texts:
On the energy meter installed by my utility company (a 1-year old digital Landis+Gyr), I noticed the following steady-state readings when my inverter air conditioner (with a variable speed compressor) was running and I am trying to figure out what could be happening
Voltage: 230V
Current: 2A
Power Factor: 1.0
Power: 315W.
Clearly the power reading is [happily] much less than expected - ordinarily I would expect power to be V times A times PF but that is not the case.
To ensure the energy meter was not defective (it's just a year old) I connected a 200W incandescent lamp and got 0.75A with 175W, which shows that the meter is correct to within a small margin of error. Can I conclude that the power shown by the energy meter is lower than VxAxPF for the AC is because the compressor is probably drawing pulses of current rather than a continuous 2Amps? (I am not conversant with the exact speed control mechanism of inverter ACs.) If so would it then imply that energy meters such as the Landis+Gyr are NOT designed to show true RMS currents?

Thanks - Ram


texts: How can I avoid voltage spikes when connecting/disconnecting a 12v battery?

texts:
I have a computer that runs on 12v from two parallel lead acid batteries. I need to be able to swap the battery banks for fresh ones every now and then without ever losing power to my equipment.

I can do this by replacing one battery at a time, that's no problem, however I'm curious about best practices when swapping large batteries that's powering sensitive equipment. Should I be worried about spikes when connecting the wires? Should I be using something like ferrite beads or diodes to protect my stuff?

Thanks


texts: How do you remove insulation from headphone wires?

texts: How do you remove insulation from headphone wires (these tiny) to prepare it for soldering?


texts: It is possible to use a 100W 12V solar panel directly to charge a laptop, using a buck converter for example?

texts:
I am planning to go off the grid due to the pandemia, to an isolated village. I am working remotely I am looking for a solar approach to power my laptop ACER A5 515. The charger is rated 40W.

I was considering using a 100 Watt panel, an inverter and the power charger. However I was wondering if its possible only adapt those 12 volts to 19 to use with my laptop. And which could be the best way to avoid damaging the electronics.

I think it should be a waste of power using an 100 watt panel from  the solar controller, then a 120 v inverter to connect the laptop charger.

I could use the laptop battery to store any excess energy (I only the laptop to be on by 9 hours at day)

Also I will need to have my phone connected as I will using the data tethering and a rechargeable usb light to use at night.

Thanks in advance for any ideas or suggestions.I am looking for an starting point to start constructing this setup


texts: Floating Nodes Error in Simulation in ORCAD PSPICE

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Does anyone have any insight as to what exactly is wrong with my circuit on Orcad/PSPICE?

My name is in the project name so I blurred it out for obvious reasons


texts: Any reason power supplies always use single sided PCB's?

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I am designing a PCB that has an onboard power supply switching module which requires filtering and protection on the input and output side. Its going to be a double sided PCB but I was wondering if the power supply section should be kept to a single layer. Just about every power supply I have seen always uses a single sided PCB.

The switching module is a 120VAC-24VDC. I am using a common mode choke, power factor correction cap, bypass caps, MOV, fuse and thermistor on the input side and filter cap, bypass cap and transient voltage suppressor diode on the output. I used a few topside traces to make everything fit neatly together. I imagine the single sided PSU's are solely for cost but is there anything I should be concerned about?


texts: PIC mcu gets programmed but doesn't get executed

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I am using 'pickit2' through Mplab to burn my code. Suddenly none of the codes (even blinking led) that I fuse through it gets executed.

I confirmed whether it writes the hex code properly using the 'Read Memory' feature. On comparison, I found no change in the hex.

I changed lot of IC's (16f/18f), I tried other boards too, but nothing worked.

What's going wrong with my setup? please help me to figure it out.


texts: Chamfer Geometry for GCPW and Microstrip

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I've seen various "recommended" chamfers for 90 degree grounded coplanar and microstrip traces. For example,   or .

Is there a "rule of thumb" for which type of chamber and which geometries work best for RF layout? For my case I'm interested in 3 to 12 GHz with a grounded coplanar waveguide conductor of 10 mils with 6.5 mil air gaps on a 6.6 mil thick Rogers 4350B substrate. But my case aside, are there rules of thumb that I can follow to ensure I have a constant 50 ohm impedance without resorting to 3D EM simulators like CST Microwave or HFSS?


texts: How to link ALU to registers, RAM and Clock?

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I've designed a basic 4-Bit ALU which computes A+B, A-B, B-A, and a few logic operations. I'm using a mux to determine which output appears at the multiplexer output. This is a basic start to a CPU as far as I understand.. where do I now go from here? How do I link it to the RAM (will be a small array of D-Type flip-flops) and the Clock? Which basic registers do I fundamentally need?

I'm a little confused as to how the components of the most utterly basic CPU components interface together and where/when/how the data travels.


texts: How do people prototype circuits without getting shocked?

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I am just getting into soldering, developing prototypes on perf boards and microcontrollers. The current for some can be as high as 2 A. I am trying to build a drone and the BEC for one ESC is 5 V and 3 A. This may sound stupid, but how do people not get electrocuted when soldering connections that carry this current. And I don't see insulation put directly on the soldered connections or on the circuit board either.
Especially when you look at prototyping in general, there are wires hanging out everywhere and likely more than 2 A coming out of the power source. At those soldered connections, shouldn't it be practically lethal to go near it? The wires insulate the paths, but the connections should be dangerous to touch, right?


texts: LTC3625 Not working as expected with LTSpice

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I am using LTspice with LTC3625.  Circuit A (1st Image) works well as expected. Circuit B introduces R2 a 25 Ohm current limiting resistor. Circuit B (2nd image failes to reach the required output voltage)  Only change is R2.

Can anyone please explain why ?


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I made a PWM Motor Controller with a Attiny45. I have a few questions regarding each section of my schematic. This design is for 40A/18V, so 720W. I know this is beyond my current skill and I take full responsibility for burning things, I try to be careful.
1. VCC / DC-DC Converter
I just took the recommended design and I hope everything is okay. If someone finds a error, let me know.
2. Battery Control
This is optional, ignore please.
3. Attiny IC
This also seems pretty straight forward, I hope I did not make any mistake.
4. Motor Control
Can I use the MCP1416T-E/OT with 5V PWM IN and 14-18V VCC together with two parallel NCE2030K MOSFETs? Is it even possible to use two MOSFETs parallel? I often see designs where there is a 100k resistor from gate to source. Is that necessary here?
Thank you for your help, I tried to keep the design simple.


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So I am currently trying to make an interactive mobile phone cover that communicates with a game on your phone. The inputs to the game will be push buttons on either side of the cover. What I am interested in knowing is: how can one measure the force that a button is pressed with? Or alternatively, how could some sort of force sensor be incorporated into or near the button(s)? It would be interesting to incorporate force into this mix as well, and use that as another input to the game.

Any ideas or suggestions will be appreciated