texts: Using the .step command to step a parameter of a transistor model in LTspice

texts:
I read this document and I want to step the β parameter of a transistor for the below circuit(to see it bigger please left-click on the image below):

Here is the model of the transistor and BF is the β:

  .model MyBJT NPN(IS=1E-14 VAF=100 BF=100 IKF=0.3 XTB=1.5 BR=3
  CJC=8E-12 CJE=25E-12 TR=100E-9 TF=400E-12 ITF=1 VTF=2 XTF=3 RB=10
  RC=.3 RE=.2 Vceo=30 Icrating=800m mfg=NXP)

Then in the above line I change BF to {BF}

And step BF as follows:

  .step param BF 10 500 50

and then

  .tran 1

But I'm not getting many plots just one.

Am I doing something wrong? Is it even possible what I'm trying to do? Is there a way?


texts:
Something odd is happening in a h-bridge design I've made.

Schematic:

The part numbers in the picture are wrong, sorry. The n-channel mosfets (the bottom 3) are all 2N7002Ps, and the P-channel mosfets are BSS84CTs. Both have >40v rating, and are logic level. Also, the +5v tag is wrong, it's just a generic rail that I'm injecting power in from.

The bottom n-ch mosfet's gate runs down to an I/O on a microcontroller (to act like an enable), and the two main gate wires go to an inverter, so that neither of them are active at the same time, and so I can control this h-bridge using only 2 pins. This driver is just running a small ultrasonic transducer, so there's not much load at all.

Everything works well at 3.3v on the +5v. The transducer is powered normally, everything "functions within acceptable parameters" as Data would say. There is no heat emitted from any of the mosfets. Unfortunately, I need a higher voltage for my application. As soon as I put the voltage to 12v (still half of what I need), all the mosfets loose their smoke and glow quite nicely for a few seconds. Also, they invariably short their gates to +24v, which also seems to toast my $12 ARM micro on the board.

Any assistance to why the heck this is happening would be greatly appreciated.


texts: Can a bird, previously at earth potential, get electrocuted by landing on a powerline at high-enough voltage due to the initial "equalization charge"?

texts:
At the voltage levels of typical overhead transmission lines in the US, a bird can land on one and be just fine (as long as it doesn't do something like spread its wings and touch a tree or something else at lower electric potential).

However, what about a hypothetical powerline at much higher voltage (as in tens of megavolts). Could landing on such a powerline fatally-shock the bird even though it does not complete a circuit for sustained current? (Assume that the distance is long enough that electrical arc'ing is impossible.)

NOTE: My understanding of what happens when a bird flies from an earth object to a powerline (please correct me if I'm wrong) is that - upon contacting the wire - its electric potential changes from earth-potential to the powerline's potential. In order for this to happen, there is an initial transfer of electrical energy (i.e. flow of charge i.e. current) from the powerline to the bird which "equalizes" their electric potential, which happens nearly instantaneously. If this is correct, then my question can be restated more generally as "Can an 'equalization charge' such as this result in a fatal shock, if the potential difference that it's equalizing is high enough?"


texts: PCB Ground Plane and Redundant Connections to Common Ground

texts:
This is a question borne of sheer ignorance, but I'm not sure if it's a good or bad thing.

I'm designing a PCB (1) that will connect to another PCB (2).  The latter has all of the power, ground, IO connections, etc.  The one I'm designing is sort of a daughterboard that will offload some of the connections.  Currently, I'm running 34 wires to the daughterboard, two of which are GND.  Because I have a ground plane, if both of these GND wires are connected to ground pins on PCB(2), assuming a common ground plane there, are there any benefits?  Are there downsides?

I did this for two reasons:

Redundancy
Ensure tolerance of all grounded devices

But thinking it through, I'm concerned about:

Creating a ground loop
Possibly different potentials due to trace length (minimal, the whole PCB(1) is roughly 4cm x 4cm)

So - should I change my design to not contain two ground wires back to PCB(2)?  I won't be mad about freeing up another wire, for sure.

Update with additional information:

This is for a 3D printer, moving connections from the main boards to a daughterboard in the tool side.

The main electronics are a Duet Wifi board and a Duex 5 board. These boards are both wired to separate +24v connections from the PSU, but the ground is daisy chained (PSU -> Duex5 -> DuetWifi) to ensure a common ground and no variance in potential.  Both boards have a variety of connectors (fans, sensors, etc) that include a ground pin.  I don't want to carry a ground wire for each of them to the daughter board as it adds unnecessary weight and eats wires that could be used for other signals.

The plan is/was to use to ground wires (one from each of the two main boards) to wire a common ground plane on the daughterboard that anything which needs grounding wires into.

My thought was that there's both redundancy and that connecting to the ground plane on each of the two main boards, whose ground planes are directly connected as well, would help to ensure potential across all devices connected to any of the three boards.


texts: How do we get output like that with full wave precision rectifier?

texts:
First of all look at my circuit.

If we assume a sinusoidal signal as input Vin then the signals V01 and V02 should be like the signals shown in the picture. From the two signal how can we get the V0 like that?

Another question is that why we take the value of resistances (marked with red pen in the picture) R/2 and R?

Actually I can't understand the full operation of the circuit. Can anyone help me?


texts: How to measure RPM from vehicle tires? Wheel Speed Sensor

texts:
I'm looking for a Wheel Speed Sensor to use it with a Raspberry Pi project to measure RPMs from a vehicle tires, however, I can only found sensor devices that I can't use with vehicle tires, they are for smaller purposes.

There are several ways to do it:

Hall Effect
Reed Switch
IR Sensor

I've found some sensors from companies but they are builded for specific devices from them.

I hope to receive some help from you guys! Thanks


texts: Help on translating 5V rotary signal output to interface with lathe's cnc controller!

texts:
I have a hall sensor (OH137 - open collector) as an index signal on my lathe’s spindle. I have the sensor pulled high by a 1k resistor and can’t change it because they’re both glued in epoxy.

This sensor works normally with 5V, from a 12V supply inside the lathe, separated from the CNC controller (Gecko G540) supply. This 12v lathe's supply powers also the lathe’s tachometer, which I suspect accepts a variety of different signals (as long they're max 5V) on it's input.

So I made an optoisolated circuit (an n channel mosfet 2N7000 and a 4N25 opto) to detect the 5v-0v change from the index sensor and had the output of the optocoupler wired in one input of my CNC controller, that sinks it's own 12V to it's own GND. (Separated from the lathe's).

So far so good, it works and the RPM is the same shown in the tachometer and in PC software Mach3’s RPM DRO. (that get's the RPM signal from the cnc controller input), so my circuit works nicely when using as input the signal from the hall sensor.

I then bought a rotary encoder, that needs 5V also, and has A,B, and index outputs. I plan to add the encoder channels to my system. The encoder is this one, and it doesn't have open collector logic, it has 5V TTL squarewave outputs:

https://www.usdigital.com/products/e...ental/shaft/H5

Attached  goes it's electrical specs

I duplicated my optoisolated circuit to have as input the index (Z) or the A signal from the encoder and wired the output of the optocoupler to another input of the cnc controller

I can'make it work on my circuit. As the mosfet is never turned on or off, so the output of the optocoupler never changes.

I even tried to replace the 2n7000 mosfet with a 2n2222 transistor and a 1k resistor between its base and the output of the encoder, still with no success.

If I wire the encoder directly to the lathe's tachometer it works. As I rotate it, the RPM (in the tachometer only) changes. So I suspect the tachometer inputs accepts different types of signals. But I can't pass it's signal to my cnc controller through my circuit.

My knowledge in electronics is basic, so, anyone could help me with my circuit? What am I doing wrong? Is the signal from the encoder different to be used with my optocoupler circuit? Should I add something to my circuit? Or change it? I’d like it to remain optoisolated...

My circuit is also attached.

I believe I would need to convert a TTL logic to an open collector logic? If it's true, is it simple to be done?


texts: How could I make a 1kW fan heater consume less electricity?

texts:
My fan heater has only two settings, 1kW and 2kW.
But what if I wanted it to consume only 200W per hour ? Could I find a device to put in between to supply less electricity, how would I do that?


texts:
I'm trying to figure out how to determine the VGS of the H-bridge (M5) in theory. D1 is a 3.3V zener diode. Since the PNP is off in this case, shouldn't the gate voltage of the PMOS be 20.7V and VGS will be -3.3V? I'm getting around -4.3V on the physical PCB. I can't really simulate this circuit as there's no available spice model for the zener diode I selected.
I'm thinking the 32.4kohm resistor is playing a part in the gate voltage as well but I can't really figure it out.
So my question is how do we calculate the gate voltage in this case?
Thank you.
Datasheets:
Q1 PNP - https://www.onsemi.com/pub/Collateral/MBT3906DW1T1-D.PDF
D1 Zener - https://www.mouser.com/datasheet/2/258/MMSZ4678-MMSZ4716(SOD-123)-V1-1626417.pdf
M5 H-bridge - https://www.diodes.com/assets/Datasheets/DMHC4035LSD.pdf
M4 - NMOS - https://media.digikey.com/pdf/Data%20Sheets/Toshiba%20PDFs/SSM6N7002KFU.pdf


texts: Can I use a battery bank to make a spot welder?

texts: I saw in a lot of youtube videos people using capacitors connected in parallel to make use of the current for a spot welder for battery tabs, I was checking my cemetery box last night and found a lot (like 60) Li ion 18650C4 batteries, they are rated for 2200mA and 4.2V nominal, I think that's a lot, if I put 60 of them in parallel, now, I'm worried for the stress I would be imposing on the bank, perhaps a low resistance high wattage lamp would alleviate the near zero resistance at the end? or is this a no no, don't do it project? I can also use them for other things, like a battery powered mini car for my kids, but what I need right now is a spot welder for fixing laptop batteries in my computer shop at the end of the world :) , I have no trouble charging them and I have been using batteries for a long time charging and discharging them with a constant current charger and limited voltage power supply, plus a temperature sensor, just in case.


texts: Inside a library of common functions (Instruction Set ----> High Level Program) is there information of how many clock cycles they use?

texts:
I am a Mathematical Person. So thinking from that perspective.

To make my question slightly more concrete. I was thinking of controlling a hobby servo through a Uart serial data stream.

I am inventing numbers for the purpose of communicating the idea.

CONTEXT:

Suppose a servo needs to be refreshed at 100 Hz and needs a resolution of 1 degree.

So this implies that the serial communications needs to send DATA (101101000) 9 bits wide. (I realize there is overhead KEEPING IT SIMPLE ATM).
@ 100Hz. Therefore 900 bits per second transfer rate.

Given that a servo is controlled by a PWM signal. And In the case of an arduino with 16Mhz clock.

That serial transfer will consume a percentage of the Time, leaving the remainder to produce the PWM signal for controlling the servo.

MAIN QUESTION:

How do I in general find "given the Library nature of programming languages" the number of low level instructions used for particular function or routine. So I can see If I have enough time to fit in in this case. The PWM signal between data transfer.


texts: How should I connect the audio ground and shield wires in a Cat5 cable for analog audio?

texts:
I would like to carry 3x balanced  line level (not mic level) signals to another part of my living room and I found that the cable space in the skirting boards would not allow 3x balanced cables (XLR connectors at the ends).

I think I can safely carry the (analog) signals using an unmodified Cat5 cable using custom converters at the ends, each twisted pair of the cable carrying a balanced signal.

How should I handle the remaining twisted pair? I think I don't have high frequency interferences in the room, but I want to ensure the best protection against ground loops and 50 Hz interferences.

Should I use both wires for signal ground and ignore the shielding of the XLR connectors? this would allow me to use cheaper plastic XLR connectors. Should I rather use one wire for the shield (connected to the metallic XLR connectors, at one side only of the cable) and one wire for signal ground? Or should I use a STP Cat5 and use both wires for signal ground, and connect the cable shield to the metallic XLR connectors at one side only?

I guess that stranded vs solid copper wires make no difference.

Related but not same: Analog Audio Signal over dedicated Ethernet/Twisted Pair Cable

Edit: it is worth mentioning that the source device is the same one for all 3x signals, therefore the signal ground of the sources is actually the same.


texts:
I have a 100k ohms potentiometer. My problem is that I have a control stick that goes from left to right representing a very small angle - corresponding to 618 ohms of the potentiometer's range. So within the first 618 ohms, I want to reach the value of 5V.
What electronics should I add to achieve this result, please?

Update
Implementing Spehro's suggestion - will this be suitable, knowing that the max value will be reached at 61mV?

Below is Math's solution:

Which of the two solutions is the best, please?


texts: How to implement SWD lines on Type A to C USB cable

texts:
I would like to add a sink only Type C port to my project (non-PD power only, no data) but would like to include 6 lines for debug purposes (SWDIO, SWDCLK, UART lines, and nRST).

I was wondering what lines would be safe to use for this (if any)? Could I use the Tx +/- (top and bottom, 4 pins total) lines plus the SBU lines? It doesn't have to be symmetrical for me, I can mark my debug cable.

That also brings up another question, if I plug an A to C cable into my computer, will using the SS Tx lines for SWD on my UFP result in any enumeration error for USB? Reading USB 3.x SS enumeration, it sounded like the Host would first poll the Rx lines for a RC time sink, if nothing is found, move on to USB2.0. What happens to the peripheral Tx lines if USB3.0 enumeration fails?

Thanks!


texts: How do thermal tapes transfer heat despite their low thermal conductivity?

texts:
I found myself needing to attach small heatsinks to Mosfets and CC power regulators. Also some high-power diodes.

Today I have learnt that thermal compounds, even best in the market, are dozens of times less conductive than aluminium or copper.

I understand thermal compound is used only to cover microscopic cracks.

But what about thermal adhesive tapes?

My question is:

Using a thermal tape, I might completely cover the surface between the heat source and the heat sink in order to join them together.

If thermal tape is 100 times less conductive than aluminium, how do they manage to do their job and transfer the heat even at high power applications?


texts:
I'm a very beginner in electronics. I'm trying to make a system which transmits a tank chemical level to a distant system.

Remote system is an Arduino.

For the tank unit I have 4 float switches. Whenever one is triggered (close/open) I need to transmit this to remote system. For that I'd like to use an NRF24.

But my question is, will it possible using an Attiny85? I mean 4 switches and wireless communication.


texts:
If I have a 48v 20Ah 1000w lithium ion battery, how long could it continually run a 48v 33Amp 2000w motor?

Also, how big of a battery would I need to have it run for 45mins at least?


texts:
I am confused when searching for a user's manual for Nokia5110 LCD. I've found User manual ET LCD5110 with
This has the same pins with different placement; therefore I don't know whether I have found the relevant user's manual.
My own LCD is the following:


texts: Can someone help me to identify this VISHAY IC? Tips on how to do this are also welcome :). I could not find anything by searching with the numbers on top of the IC. The IC is used in a MKS 649B Pressure Controller.


texts: What are the different types of digital signals

texts: In a digital logic class I was taught that a digital signal is one whose y-component, voltage, is discretized but whose time domain is continuous. In a signal processing class, we worked with digital signals that may have 8 bits of discrete voltage values, but were also discretized along the time domain as they were samples of speech. Are both of these signals true digital signals?


texts: Bridge rectifier filter capacitor remove

texts: My question is very simple. What components should be removed from the following circuit diagram for this circuit to work only on DC voltage? I'm sure that the bridge rectifier should be removed further than that I do not know.


texts: Need a non-volatile memory IC with near unlimited read/write operations capability

texts:
I need a memory solution which is going to be used to keep track of an accumulated count on a micro-controller based project.

By accumulated count, I mean to say that the micro-controller uses this memory location to keep count of the occurrence of an event. The count needs to be preserved during power outages, hence the need for NON-VOLATILE memory.

Also the occurrence of the count increment event is frequent hence there will be a lot of writes to the memory hence my hesitation to use EEPROM.

The preferred communication interface will be I2C, but other alternatives are welcome.

Off the top of my head, I envision an SRAM low-power volatile memory IC with the option of being powered by a backup battery like a coin cell on power-downs.


texts: Why doesn't shoot-through occur on totem-pole structure?

texts:
I'm designing a totem-pole by BJTs in order to drive a MOSFET. I studied on several online examples and built up my circuit according to what I understood from them. However, there is a detail which got stuck in my mind. I would like to know why doesn't shoot-through occur in this circuit during the transition time of the clock pulse (e.g.; when \$V_{clk} \tilde= 6V\$)? In other words, why doesn't the two BJTs become turned on at the same time during the transition?

simulate this circuit – Schematic created using CircuitLab

Simulation result:

(Vtp and Vgs overlap.)


texts: Obtaining GPS Pseudoranges from Code Phase

texts:
After the tracking process in a Software GPS receiver, I need to compute the pseudoranges between the receiver and the satellite (without having in mind the clock corrections). In the tracking process I obtain the Code Phase in chips for each satellite, which actually is the "pseudorange". So I compute it as:

Code_Phase/1023(chips/msec)*1E-3(msec)*3E8(speed light)

Where I obtain a certain value in meters. For example:

92.57/1023*1E-3*299792458 = 2.71E4 m

Am I computing the pseudorange correctly? or Am I forgetting something important? Since I compare this method with other I know it's correct, and both pseudoranges are quite different (for example in the given example, by this other method I obtain 2.17E7 m).


texts:
This is one of two bridge rectifiers recovered from a failed LED lamp.

I've seen the 'backwards R' before but don't know what it means/identifies. The other logo on the left is one I've never seen before. Can anyone identify/explain either of these? Thanks.


texts: I'm trying to power a 12v 5rpm DC motor using a 2ch relay board and some 18650s. I am also using a MT3608 boost converter and a TP4056 to make the whole thing rechargeable. I'm having trouble that when the direction of the motor is changed too quickly it causes the whole circuit to shutdown until I reconnect power. I believe it is something being triggered on the charging board, because when that is removed there is no issues. My questions is there a way I can circumvent this problem. I would imagine there is a much more efficient way to do this (and if there is please let me know), but this was just a small project I was working on with stuff I had laying around. Any help would be greatly appreciated!


texts: Can we use a capacitor with battery to fast charge it?

texts:
Consider this. Many capacitors connected in parallel to an input line, those capacitors are in series connected to battery. Whenever we need to charge, we plug in adapter that charges the capacitors. Since all are in parallel, they charge soon, since being capacitors, can charge faster too. All these capacitors can be connected to a battery in series, so one capacitor when gets depleted, the charge flows from the next capacitor, the capacitor nearest to the battery is fully charged and keeps charging the battery slowly. Will this work??
Ps: the idea is to make fast charging work by using capacitors to hold temporary charge and use it to charge the battery.
So battery can be connected in series  with capacitors to achieve this?


texts: Double wall AC socket with load on one side and power supply

texts:
I have on AC socket a load wire on the right side.
I want to connect a power supply with separated load and neutral inputs.
How to handle the case when a plug will be put on the top, next on the bottom of a socket? The load wire will change the place and the power supply will be damaged?
Power supply
https://www.meanwell.com/webapp/product/search.aspx?prod=LRS-350
Sockets:

Plug:


texts: Finding a diode's operation point (Q-point)

texts:
I'm struggling with what should be a fairly simple excercise, I have to determine the diode's Q-point using the load line method given the diode's characteristic curve, however if you look at the wikipedia entry, you would see that the method is described for a circuit consisting of a voltage source, a resistor and the diode connected in series.

So far I've used Thevenin's theorem to obtain a circuit for the load line analysis, the values of the equivalent circuit that I found are:

\$ V_{th} = 3.36 v \$

\$ R_{th} = 66.95 \Omega \$

But, if you look closely on the characteristic curve you'll see that the load line's cut-off point (3.36, 0) is NOT in the graph. So maybe my mistake is in finding the equivalent circuit or maybe that's not the correct way to approach the problem, so I wonder if the load line is calculated from the circuit or if it is chosen and then calculations are performed on the selected values.

Any help is truly apreciated.


texts: Power supply for a 3.3v portable device based on dsPIC33FJ128GP804

texts:
I have been building a portable device which has as its main components a dsPIC33FJ128GP804 and a graphical liquid crystal display, which is working fine.

The PIC voltage range is specified at 3.0v to 3.6v, and an absolute max of 4.0v. The LCD has a very similar voltage range.

While operating, the device uses about 60mA of current and when in sleep mode, both the PIC and LCD can drop their current consumption down to a few micro amps.  I was hoping to not need a power switch and just put the device in sleep mode when no buttons have been pressed for a few minutes.

I have been experimenting with different ways of powering the device, initially hoping that I could power it from 2 AA batteries.  However it doesn't take long for the battery voltage to drop to a point where the PIC becomes unstable.

I added a surface mount 3.3v regulator (AMS 1117) and tried running the device from 3 AA batteries, but now in sleep mode the current consumption has risen to 3mA which is not ideal.

I experimented removing the regulator and using a few 1N4001 diodes to drop the 4.5v to under 4.0v, but I am not too convinced with the reliability of the results.

I was wondering if anyone could suggest a better way of powering this device to get a good battery life and a still be able to use sleep mode?


texts: Can I use crystal + driver(op-amp) to generate waveform

texts:
Now I need to design a high frequency generator(about 2MHz). Can I just use a 2MHz crystal + low offset current op-amp to produce a +-15V,10mA square wave signal?

If not, what would be the problems in my idea? And what structure I should use to generate such signal?(+-15V,10mA output, the actual value is not matter if not higher than +-18V; and the frequency is 2MHz, about 10% accuracy, and the rising and falling time are around 5% of the signal period time)


texts: Bypass caps under BGA: Should I isolate vias from planes?

texts:
I'm placing bypass capacitors underneath a BGA package. In some cases the caps cannot land directly on the vias-in-pad ("VIP"), so I'll need short traces from the VIPs to the caps:

In this example image, the cap is 0201 (0603 metric) and the BGA has 0.4mm spacing. The VIPs are 6-mil (0.15mm) holes filled with conductive material. In the actual design, I'll have wider connections between the VIPs and the capacitor than shown here.

However, this causes the following problem: The BGA balls are connected to the power/ground planes through the inductance of the VIPs, and then there is additional inductance (the other half of the VIPs) between the planes and the cap on the other side. My concern is that the capacitor won't actually accomplish much, since any noise will hit the planes first and will be partially isolated from the capacitor.

A possible solution is to run the VIPs through the PCB without having them contact the power planes, then to the caps, and place an additional set of VIPs (to the power planes) on the capacitor pads. But then I've really increased my loop area, which I obviously don't want to do.

Are these valid concerns? What are the best practices here?


texts: Whats the difference between bode plot linear and cartesian?

texts:
As in title, Whats the difference between bode plot linear and cartesian in LTspice? In both cases i get V(f) but the values differ. Which plot will give me values of voltage at given frequency that will actually appear if i measure it with multimeter?

:EDIT

Thanks for the responses. The final answer is:
Bode gives us [voltage]*e^(-i[angle]) while cartesian
gives sqrt[(Re)^2+(Im)^2].
Answering my question, voltage that will appear on the multimeter can be directly taken from [voltage] of bode plot


texts: Leaky integrator from Switched capacitor integrator?

texts: I have seen leaky integrator circuit using a capacitor and resistor in parallel between inverting terminal and the output of an op-amp. But I was wondering if it is possible to make a leaky integrator using switched capacitance integrator.


texts: What's the correct way to safely splice into a wire meant for mains voltage

texts:
I want to use a relay to control some 230VAC equipment, by doing so i want to toggle the live wire.

Is there a standard/safe method to do this in terms of the components to use, or is it a matter of cutting into the outer sleeve, then cutting the live wire, and inserting them into some screw in terminals like this which then connect to the relay?

Edit: Of course the wire will be not live when I'm working on it.


texts: Problem with wide voltage range CC sinking

texts:
I want to sink ~10 mA of constant current at wide range of voltages even lower voltages like 10 mV, below circuit suggested to me in one of my older questions:

simulate this circuit – Schematic created using CircuitLab

The problem is when input voltage is zero, output will became negative (link to simulator):

Making another path for the current to flow solves the problem to some degree but the output is still negative (link to simulator):

How can I prevent the output from getting negative?


texts:
I want to read high voltages, around 150VDC, using a ESP32.

I plan to put this as an input into the ESP32 ADC pin. But of course, i shouldn't have voltage that high on the input of a ESP32.

In ESP32 datasheet tells that ADC max input is 3.3 V with 12-bit resolution (0-4095). So, i just need to scale it down from 0-150 to 0-3.3 VDC.

So,  i use simple voltage divider to achieve this.

Vout = (R2 / (R1+R2))  * Vin

if i want to scale it down about 1:45, then:
R2 = 1kΩ
R1 = 44kΩ

My question is,

Is this going to work?
How is the accuracy and stability?
Is it safe (when something wrong, not gonna break my ESP)?

Thanks in advance!


texts:
i'm trying to get my head round two intermingling factors relating primarily to an rc low pass filter and bypass capacitors for providing a low impedance path for high frequency AC signals, essentially filtering them out.

I was initially confused by the need of a resistor within an RC filter. But the following picture explains how the input port matches the output port. (Actually taken from another stackexchange question)

But then looking at bypass capacitors:

I understand these can provide voltage if it dips, but i have not found a reasonable explanation as to why an rc filter requires the resistor but a bypass capacitor can take out high frequency signals without one? Essentially filtering, low pass filtering?


texts: Can I make a peak voltage indicator with a small number of components?

texts:
I have a switchmode power supply that rectifies the main voltage with a full bridge rectifier and smoothes it with electrolytic capacitors. Assuming a 115 volt AC power supply, this gives a peak voltage of 162.64 volts DC on the electrolytic capacitors. We can call this +VDC

If the mains voltage drops under load, I would like to have a light that turns off on the display. This serves as a visual indicator that the mains supply has unacceptable voltage drop. This is common if you are in an older home or at the end of a long extension cord.

The first circuit I imagined is a 1N4007 connected to a tiny capacitor. This voltage source is connected to the base of a NPN transistor via a potentiometer and resistor. By adjusting the potentiometer, I can cause base-emitter current to rise as the +VDC crosses some voltage level. This would turn on the NPN transistor. The collector of the transistor would be connected to a LED and resistor fed from +5 VDC supply. The 5 volt supply would need to share a common ground with +VDC.

The above circuit would light once the base-emitter breaks down. The issue is the hysteresis on this would be enormous. Even if +VDC dropped significantly the NPN transistor would stay on enough to light the LED. I know I can use a resistor across the base-emitter to lower the hysteresis (and also gain). But I don't know if the solution would work well enough.


texts: In I2C bus protocol What is role for Combination of Pullup resistor and Slave device pin Capacitance? Because any one of the slave address send by master through bus the resistor and actual slave device pin capacitance look like RC circuit (time constant). Could you please explain when its play role?


texts: Impossible looking solder points on NRF24L01+ module

texts:
I cannot even fit two dupont connectors side by side.
I am really quite uninitiated in electronics, being a software developer.
Is this an industry standard or some sort of way to connect this?
It's the first time I've encountered so small gaps.


texts: AVR 1.1V Internal ADC Reference Over-Voltage

texts:
If I use the internal 1.1V reference for the ADC, and my Analog input exceeds 1.1V, lets say 2.5V, is that harmful to my microcontroller? Or will ADC value simply clip (to 0x3FF) at 1.1V?

For convenience, I am including an excerpt block diagram from the ATMega328 datasheet.


texts: Is there any GPIO expander with galvanic isolation? I browsed a lot and couldnt find any GPIO expander with isolation.Thanks in advacne


texts: what pipeline ADC power consumption when scaling

texts:
In a system of 10bit pipeline which consists o 1.5bit pipeline sections and the last section is a 4bit flash ADC.
The first stage of pipeline consumes 20mW,the next stages where "scaled" to keep a constant KTC noise.
ALso the input capacitance of Flash was scaled also.
I need to know ,what is the power consumed by all pipeline amplifer stages after "scaling"?
We have a 10bit system so 6bits are 1.5bits and 4bits of flash,So we have 6 stages of 1.5bit pipeline one after the other.
Each 1.5 bit stage has X2 amplifier so by using the expression bellow in order to keep the same KTC
1st stage C
2nd stage 0.5C
3rd stage 0.25C
4th stage 0.125C
So what is the link between the capacitances and the power they consume?
What is the link between the sampling frequency and consumed power of the amplifiers in pipe line?
The closest thing i thought was the GBW=gm/C definition but i dont know how to link the GBW definition to consumed Power.
Basicly its a question about power consumption of an amplifier based on its capacitance.
Thanks.


texts: Are there sites to build circuits online using equipment such as Fluke 45 Digital Multimeter,  GW-Instek GFG-8216A function generator, Agilent E3620A power supply and Tektronix TDS1002B oscilloscope rather than a breadboard? This would be a useful tool to prepare for circuit labs using similar equipment.


texts:
I am assembling a board for a wireless charger based on this evaluation module (see here)
I own a preheat bed, a hot air gun and a quality soldering iron.
I am afraid that after soldering the chip and all its accessories, I have burned it.
I took the chance at verifying every input of the chip (using a microscope and oscilloscope) to determine if I have the correct values.
Here's a diagram:

The red question marks are outputs that should show some voltage, but show 0.
The green checkmarks or x are valid inputs or the part is not needed.
I made sure all the inputs were correct, but I get nothing for output. I should see some PWM signal through PWM_A and PWM_B and also LED_A, LED_B, and LED_C
I also checked the stability of the 3.3V line, and it sits within 10mV

I used the following technique to solder the chip:

I applied solder paste to the chip
Placed the board on top of the preheating bed and turned the device to heat up to 280 celsius
I applied some flux and then I started using the hot air tool at 360 degrees for about 20 seconds
When the chip looked stable on the board, I turned off the heat bed and waited for it to cool.
Finally, I used a soldering iron at 370 (with a wide tip) to remove excess solder

Do you have any thoughts on this? Did I kill it?.
Later Edit:
Photos of the chip itself from three different angles so you have an idea:

To me it looks fairly well soldered. I took the pictures using my 1500x microscope (the same one I used to test the pins themselves with the oscilloscope)
Another argument here would be that I tried to "feel the resistance" of the lead with the tip of the oscilloscope probe and the visible lead tears formed between the pads and the chip pins were there.
Still, any idea?
Later Edit 2:

Photo of the chip in PCB design


texts: Help wanted with Vacuum Fluorescent Display (VFD)

texts:
In a box with old components I found a 16 character, 19-segments Futaba VFD:

I would like to use it for "something" but I haven't the foggiest how to drive such a display. Even the filament is an unknown factor to me. The device dates at least from the early '90s. I guess at that time there were drivers for it, but I don't know if this kind of displays is still being designed-in. So, information about a driver would be nice, as would some schematic about the whole (i.e. what voltage does the filament require with respect to the driver voltages?)


texts: Upload firmware to many controller ICs at once

texts:
I have some 100 Atmega328 IC boards. I want to upload firmware in all of them at one go and I have the final firmware code. Is there any method by which this can be done?
I was reading somewhere that it is called firmware loading, but not the process.


texts: How much DC voltage is needed to brake a 3 triphasic motor?

texts: What would the nominal parameters of the bridge rectifier and the transformer be?


texts:
I just want to know the correct way to calculate \$Z_{in}\$ in this network. It's very simple but I think I might be doing something wrong. Is it ok to calculate the impedance over one line and get \$Z_{in,1}\$ and the same way for \$Z_{in,2}\$?. That way we get the same on both of them so \$Z_{in}\$ should then be just the half of \$Z_{in,1}\$ because they are in parallel.

Ok, just to clarify, the overlapping lines are lines that go from the impedance \$Z_1\$ and form two parallel transmission lines so on both sides we have transmission lines with length \$ \frac{\lambda}{4} \$ (quarter wave transformer) with a line impedance of \$ Z_{L}\$. How can i calculate \$ Z_{in}\$ correctly in this problem.


texts: Can I produce a square wave(basically a clock) from a USB port on my Laptop? If yes how?

texts:
Can I produce a square wave(basically a clock) from a USB port on my Laptop?
  If yes how ?
Briefly explaining, I am using ad9834 in a project and this chip needs a clock  of any frequency ranging from 1MHz to 75MHz. This project is powered by USB ports of a Laptop. So i want to generate a clock.
Also I am using ATXmega 128A3u(on a board, which has 16MHz crystal oscillator) to control the above said chip. So, is there any code to  access this clock?


texts: What are the possible disadvantages of using this PNP transistor?

texts:
I read this application note  from Fairchild Semiconductors, and was wondering about what the possible disadvantages could be if a PNP transistor is used to bypass the Miller current as shown in the application note.
Would the increase of stray loop inductance be a possible problem since a PNP transistor will need some space to be put on the board, and that means the gate driver IC would be a bit further away from the main IGBT or MOSFET?
EDIT 1:-
This is the part from the document I was asking about:-


texts:
Can any one tell me what I would need to replace this yellow disc.  I have another board that this part has burned up, and I need to find a replacement.  The manufacturer is Buss, however I cannot find any information with the numbers printed on it.  The following is printed on the side:
Buss
M131
EL

I have also included a picture
Thanks in advance for your help


texts: I have a mosfet controlling power to a heater. I send pulses (akin to pwm) to tell the mosfet to turn on and send current to the heater. The pulses are coming from a Beagle Bone Black. The process on the controller takes the feedback from a thermistor and sets the output pin that's connected to the mosfet high, when necessary. If the program halts or freezes with the pin set to high for more than 10 seconds, then the equipment will catch fire. What kind of circuit can I use to limit the length of the high pulse to only 1.5 seconds? It is expected that the pin will transition from high to low in less than 1.5 seconds (henceforth reffered to as the limit time) but can make multiple transitions (low to high to high to low) many times per second. The frequency could be as high as 250hz.


texts: How to open a components' schematic symbol for editing quickly in Altium

texts:
Let's say I have a component in my schematic in Altium. I can see the schematic library it came from and its Design Item ID. However to edit it, I need to open the schematic library and look for the schematic symbol manually.
In the "Components" panel I can click on any component and select "edit", however I still need to manually select the library it is in, find the component and then right click on it to access this menu.
Is there a faster way to jump to the schematic symbol in the library directly through a component that is in a schematic?


texts:
I cannot find any information on this I can understand, is this even the right place to post this question?

Asking in regards to the evaluation of different designs


texts: Could someone point me in the right direction. What I'm doing here is I took the insides from a cheap Bluetooth speaker and I would like to rewire it to an headphone jack (male). I have the cable ready and it has a red, white a copper wires (3 of them). That's where I run into trouble. The Bluetooth speaker that I'm using was a 2.1 channel. I'm not sure how to rewire a total of six wires onto only two. My guess is that I could just ignore the bass channel and focus on the L&R. Any help would be appreciated.


texts: Current/milliamp rating of adapter versus device requirement

texts:
Possible Duplicate:
  Choosing power supply, how to get the voltage and current ratings?

My DC adapter for a cordless mike has broken It' ratings are:

Input 230-240V ~ 50Hz 30mA
Output 20V 250mA

Living in a country where it is not always possible to get the things we want, we often have to improvise.

I have an old laptop adapter - input 100-240V 50-60Hz
Output 19V 1.58A  (not mA!)

Can I use this to supply the power to the control box for my mike?

Thanks very much

Pieter


texts: Can modems be used to communicate with RC Submarines?

texts:
With reference to this video"R/C Sub, Scratch-built From Sewer Pipe" when the sub went to deep it lost the signal to the RC receiver.

Question: Since water transfers sound better than radio waves would it be possible to connect two 33.3kb/s modems via a water medium?

The thinking is that the modems will be connected to hydrophones that will sit in the water and in the sub. They will negotiate a link at start-up and maintain that link (full duplex). The some simple uC will interoperate the digital data into actionable commands.


texts: What are the ways to allow/prevent a car engine from starting up?

texts:
Assume that I do not want to replace a factory Engine Control Unit (ECU) with a custom ECU.

What are the other possible intercept points that I can use to allow/prevent a car from starting up? I only want to allow/prevent starting up.

I can think of possibly connecting the car battery through a relay and turning the relay on/off. Any other good ways to do it?


texts: PC monitor flickers/resets when washer motor switches on or off

texts:
My room is next to our laundry and I've recently got a new PC monitor. I've noticed each time the motor in the washing machine is switched on or off, my monitor flickers/resets. The monitor is 32" but it isn't that power hungry (~40 W). The washing machine is a top loader. The monitor flickers/resets only when the motor is switched on/off and not when it's running. The dryer does it too. Lamps and lights don't dim though. My old monitor is fine too. I've tried turning on a kettle in the laundry and that has no effect.

Does anyone know what might be causing this? Is it EMI interference or is it voltage drop?


texts: Switching between two power supplies with a P channel Mosfet, Is VGS or VDS a problem?

texts:
So I am using the following circuit to switch between VIN 0-30v and USBVIN 5v.

I thought I found the ideal solution until I realised the FET in the schematic only has a max VGS of 8V. But I don't fully understand how the max ratings work in a situation like this because when VIN is supplied both the Source and the Gate will be the same voltage.

Also the Vds is only 20v as above the Fet isn't being used in a normal application so I'm not sure if this will cause a problem?

So my question is will the circuit be ok along with the FDN340P or do I need to swap it out with a FET with a max VGS and VDS of at least 30v?


texts:
I am wanting to monitor my household's power from the single phase 3 line input I have coming into the house.

I have 2 CT clamps to put over each of the "hot" legs to measure the current, and then I was going to measure the voltage using an AC-AC adapter (to step down the voltage and isolate from the mains) in order to correctly determine the power.

My question is - shouldn't I actually be using two AC-AC adapters, one for each side of the fuse box?  Although I guess if they are out by 180 degrees in relation to one another, then I can just determine the voltage through one AC-AC adapter and use the 180 degree fact to calculate what is on the other hot leg?  Is there a problem with this approach?


texts: Unable to start calculating this voltage divider

texts:
I'm trying to solve all kinds of voltage dividers for an upcomming exam, but I'm stuck in this one. I've solved it in LTSpice, but I cannot solve it on paper.

LTSpice showed me, that the Ux=3V, but closest to that, I got to 3.333V (which I got from a voltage divider equation Ux = (5V*2000)/(1000+2000)).

I need just a "kick" for the start on how to start solving dividers as this one.


texts: I am a 3rd Engineering students who is preparing for analog/Mixed Signal design job. I want to do a project regarding PLLs. Which PLL should I choose to make.? There are different types of PLL architecture available namely Analog/Linear PLL, DPLL and ADPLL. Which PLL is the best for me to start with?


texts: My question is about how dangerous a momentary amount of current is vs the duration.  Like is there a reasonably consistent relationship between current duration through the body and relative danger?  I.e. 1 amp for 1 second vs 0.01 amps for 100 seconds.  I imagine that's a bit complex to determine, but otherwise is there a duration for which a normally deadly amperage would shock someone but not cause a heart attack?  I read an article about research into a possible electric weapon that would shock someone on the scale of nanoseconds to stun them without risking killing them.


texts:
I'm designing a circuit to process an signal from an Rogowski coil. As the voltage is the differential of the measured current, we have to integrate the voltage to provide a representation of current.

My question is; with the RC integrator, is it as simple as ramming a capacitor on in the feedback of a inverting amplifier? As the RC integrator naturally acts as a high pass filter, do I just select the gain resistors I need and then select the capacitors value depending on what the -3dB cut-off I want? What considerations need to be made to provide the best output signal possible?


texts:
In short, I want to create a flat laser plane that knows where it's being penetrated.

If flat distance lasers do not exist, what other options do? I considered using several regular distance lasers to make a "web" and accomplish the same goal like this:

but the regular lasers might be too bulky. I'm not sure if optical sensors are appropriate or accurate enough.

What is an alternative sensor or technology that may apply to this problem?


texts: What is the difference between MCU and TTL screens?

texts:
I'm trying to build a HDMI decoder board for a 4in 480x800 IPS display. I found an HDMI decoder board on adafruit(https://www.adafruit.com/product/2218) which says it works for most 40pin TTL displays.

The display I'm intending to use has 51 pins and says it has an RGB/MCU interface.

I'm trying to look at the schematic and see if I can modify it and make a board that accepts the additional pins of my display but I'm not sure what the difference is between MCU and TTL?

I know the chip used on the adafruit decoder board (TFP401) supports both screens since I have an off-the-shelf 4in IPS display that uses that same chip.

Here is the datasheet of the display I plan to use: https://www.scribd.com/document/383775532/4in-IPS-display


texts: How to use MOSFET as an active load resistor?

texts:
In the Albert Malvino's "Electronic Principle" book, an active load switch is done by using a MOSFET as an active resistor by connecting the gate to drain(two-terminal device)(figure a)

Two terminal MOSFET act as a pretty big resistor (15V/3mA=5kohm, 10V/1.6mA=6.25kohm and etc.).(figure C ) BUT when I tried to plot in proteus the same graph using a 2n7000 EMOSFET:

The current is too big, thus the resulting resistance is too low that's why it cannot act as a resistor to properly saturate my circuit. (5V/280mA=18ohm, 10V/1.65A=6ohm, 15V/3.6A=4ohm) RESISTANCE TOO LOW!!!

My circuit diagram is just the same as figure a. Why does the 2n7000 cannot act as an active load in my simulation? Or are there only a specific MOSFET that can act as an active resistor?


texts: What cable standard is needed for UL94V-0 device

texts:
I'm designing a device that has UL94V-0 rated plastic parts. So far so good. But there are also a number of cables inside the enclosure and cables use different ratings..

What would match UL94V-0 in terms of flammability? FT-1? FT-4? VW-1?

update
On more research it appears CSA FT4 is unreasonable as it's for long building runs so most likely candidates are CSA FT1, UL VW-1 and IEC 332-1.

If someone's really interested, here's comparison of the various standards:
http://www.lappusa.com/Cableatt-Flame.htm

And what goes on in IEC60332 tests:
http://www.leoni-industrial-projects.com/fileadmin/bu/ip/pdf_-_technische_Infos/BRANDTST_ENGL_2008.pdf

Finally, a post from 1999 about this very subject:
https://www.mail-archive.com/emc-pstc@listserv.ieee.org/msg10570.html

Even more cable burning info:
http://www.caledonian-cables.net/product/Technical%20Lib/Fire%20Performance%20Testing.htm#U

And the obligatory video:
https://www.youtube.com/watch?v=Z__CfyGQ4IU


texts:
In this circuit we have a LM339 comparator which compares input signal with respect to the threshold value which is 4 volts.

This is the output of the transient analysis.

If the input signal is above 4 volts, the comparator produces a logical "1" at the output.
Let's say we would like to make a battery charge controller circuit using this circuit.
If the battery voltage reaches upper threshold (4 volts in this case), we would like to cut off the charging voltage.
There might be many ways to achieve this but the first thing that comes to my mind was to use a circuit element with a memory.
So, I decided to use this SR latch.

When I connect the output of comparator to the input of the SR latch I get this result.

As you'd see from the transient analysis result. When we make set logical "1", Q output does not become logical "1"
Should I invert the set signal and give it to reset input?
Any ideas would be apreciated. Thanks.
Update :
After reading the comments I've made some changes in the circuit.
I used TLV301 instead of LM339. I've fixed the orientation of the Q1 transistor.

You may found the transient analysis results when set is not connected to BJT circuit.
If the input voltage is over 4.2 volts comparator produces logical "0" and if it is under 3 volts it produces logical "1" again.

If I connect comparators set output to the input of the SR latch I get this result. As you'd see output of comparator scaled to about 1 volts.

These are the Q and Q_bar output of the SR latch.


texts:
I am building an antenna with aluminum elements.

Is there any easy way to solder copper wire to the aluminum? I do not need a very strong connection, just a good electrical connection so I can then apply glue etc.

I tried sanding the aluminum and applying cooking oil, but that didn't seem to work. I will try motor oil later, but I don't think that will be any different.

The aluminum is a 1/4 inch rod.

I got it to work on aluminum foil, but it won't work on the rod for some reason?

Would something like this work?


texts: Maximum output voltage from photo sensor to detect high intensity pulse of light

texts:
I'm trying to work with the OPL550 photologic sensor http://optekinc.com/datasheets/opl560.pdf (Sense a pulse of light around 8kW/m^2 in intensity and around 100us in duration to trigger data acquisition.)

I believe I'm using the OPL550 totem-pole output. I'm reading all three transistors to be switches. If switch 1 is on, 2 will be on and 3 off. Thus Vout=Vcc. If switch 1 is off, 2 will be off and 3 on, Vout=GND.
It says that the maximum input voltage is 10V, but the maximum voltage output is 35V. Looking at the circuit, I think that max output is always limited to Vcc. Applying 3.3v and 1mA source causes a voltage drop of around 2V from my DC power supply.
Can someone point out if I'm wrong in my analysis, and perhaps what is going on? Thanks.


texts:
Are there IR diodes out there? I do not need a reverse-bias IR receiver, I need the opposite (which I think will just result in a simple diode). Basically: When the sensor "sees" IR light I would like it to NOT allow current through.
The reason I need something like this is because I would like to hook them up in parallel. This way the instant one of the diodes stop "seeing" IR light I can get a +5v (1) on my DAQ otherwise GRN (0).
Let me know if I'm going about this the totally wrong way.


texts: Calculate Charge time of capacitor with current limiting power supply

texts:
If I have a 10VDC supply current limited to 1AMP to charge a capacitor through a 1 ohm resistor, what will happen and how long does it take to charge? I need a capacitor that can "eat" this power for 2ms.

1A*1ohm = 1VDC

When I don't have a capacitor connected, the voltage out of the supply reads 1V, because the resistance is only 1 ohm. But when I add the capacitor, the voltage accross it reads 10VDC. I know that the capacitor builds up in voltage as time passes. Is this voltage buildup linear with a constant current source?

Given a certain Capacitance, how do I calculate the voltage at any time T?

If I use a resistor higher than 10 ohms, will my current drop below 1A? Does the resistor still have the same operation at ALL resistances under 1 ohm?

(yes the current regulator shown here is set for 1.25A) That's what I'm designing for.

I expect a 3-4V drop across my current regulator+resistor.
What happens if my load is only 2.2 ohms? Will the gate of the MOSFET still reach ~6-7V?
I'm wanting to delay voltage to the MOSFET gate reaching 5V by more than 2ms.


texts: How to connect two PCB under the angle less than 90 degrees using stable connection (e.g. soldering)?


texts:
I was reading out a book and it said to prove that
\$y(t) = sin (t)  x(t-2)\$
is time variant, so far of all the inputs I have tried, as well as the general input of giving a shift of T, the system seems to be time invariant.


texts:
I bought this claw (it came with no instructions):

It has 2 wires only. By default the claw is open. When I power it, it closes.

With 5V it barely moves, with 12V it closes but the strength is too weak. I guess I need even more power? or AMPS? Or do I need to handle this in another way with a regulator? Voltage regulator? I'm sorry I lack of experience with this part. I usually do my projects with a Raspberry Pi but never had something that takes more than 5V.


texts:
I've made a small 6V DC motor, hand would field and armature coils, and a 1/2" copper pipe commutator with copper wire 'brushes'  The design came from an old book. 'Electrical Things Boys Like to Make'.  Problem is arcing between the brushes and commutator is erroding the commutator and the friction slows the motor down and increases current draw.  At higher speeds the ammeter reads only 0.5 amps but as it slows, it increases to about 1.6 amps.  Seemes a lot for a 6V lantern battery.

Any thoughts?  This is a great hobby but I'm not a designer...


texts: What is LT3748 Sense Resistor Power Dissipation?

texts:
I am using LT3748 for Flyback converter design. In datasheet (https://www.analog.com/media/en/technical-documentation/data-sheets/3748fb.pdf), given formula for Rsns value (pg 21) is Rsns=100mV/Ilim, Ilim being the desired maximum output current. Instructions for Rsns selection are given on pg17.

For 2A max output current, Rsns should be 100mV/2A = 0.05R. My problem is that I can't figure out what is the min power rating I need for resistor (I have 330mW power rated resistors that I would like to use).


texts: How do I go from arduino breadboard to creating a real device

texts:
My first arduino project, I have made a headlight sensor that will activate an outside light when car headlights hit it.  I know I could go buy one, but where is the fun in that?

Now I would like to make a "real" one to mount outside my  house so I can reuse my arduino.

I really have no idea where or how to start.  I have had a look but can't find any info on this...I am sure someone here will be able to suggest something.


texts: Control voltage required to turn on the LED through an NPN

texts:
simulate this circuit – Schematic created using CircuitLab

For this circuit, I am trying to figure out the value of \$V_1\$ DC which will turn on the LED, D1.
Since the forward voltage drop of the LED is 1.8V,

$$
I_{R_3} = \frac{5-1.8}{220} = 14.5\ mA
$$

To find the required \$V_1\$, I would use the gain of the transistor to find \$I_{b}\$, where \$I_b = I_c \beta_f\$. Then,

$$
V_1 = R_1 I_b + 0.7\ V
$$

(Am I right in ignoring \$R_2\$, since it is just connected to ground?)

The problem is that the gain of the transistor is not given. Is there another way to work out the value of \$V_1\$ required to turn on the LED, without using the gain of the transistor? Any help would be much appreciated.


texts: Measuring power consumption of a design ranging uW to tenths of mW

texts:
I want to measure the power consumed by my design ranging from uW to tenths of mW. Power values I wish could be recorded digitally so that I can use them for analysis later. May be another form is also fine. But I don't intend to write them down.

The design has about three levels of power consumption. Deep Sleep, Processing and Transmission.

The reason I want to do this is because I want to analyze my own design and get to see if I can further its power efficiency. Another reason is I want to include the same in the conference paper I wish to publish later.

There is only one power input for the whole design. working voltage is 3.3V. Current bursts range from 2A (ms range) to uA (minutes range). One cycle includes Acquisition, Processing and Transmission which takes about 1.5 minutes.


texts: Parameters of induction motor from p.u to actual value

texts:
What would be the actual value of stator resistance and inductance of this motor in ohms, not in p.u?
Can someone give me a valid formula for calculating it? I get the "p.u" idea but I'm not sure what is "nominal value" of resistance for a motor and if the same value is used to calculate "p.u" for both resistance and reactance. Thanks in advance


texts:
In a list of ICs, along with the familiar package names such as QFN32, LQFP48, etc., I've seen a few ICs to be listed as DIE for the package size. I've never seen that description before as an IC package size, and Wikipedia does not list it either.

What can it be?

I assume it's some kind of chip-scale package, but it does not reveal the silicon size or any other properties, like number of pins, etc.


texts: How to find current drain out of a connected USB device?

texts: I am in the process of creating a tester for production for a custom USB programming device made by my company. In this tester, I am connecting the custom USB device to our computer, and I am not sure if there may be some current drain on the device, in which I will have to supply with an additional power supply. How do I find this out?


texts: Why does a resistor need to be on the anode of an LED?

texts:
Please be kind, I am an electronics nub.  This is in reference to getting an LED to emit photons.

From what I read (Getting Started in Electronics - Forrest Mims III and Make: Electronics) electrons flow from the more negative side to the more positive side.

In an example experiment (involving a primary dry cell, a SPDT switch, a resistor and an LED) it states that the resistor MUST be connected to the anode of the LED.  In my mind, if the electrons flow from negative to positive, wouldn't the electron flow run through the LED before the resistor; thereby making the resistor pointless?


texts: Achieving MPPT of a solar panel with LM2596

texts:
im having some trouble with DC converters in a solar system.
I have a solar panel of 21V (Voc) and 1.33 (Isc).
I have studied that with a DC buck converter with input regulation (Feedback loop taken from the input) would result in a fixed output and equal to the MPP.

The thing is that i have a LM2596 adjustable regulator , and i was thinking about soldering the resistor divider taken from the output of the original topology, and take the input as a source.
Could I get the MPP voltage and current?
If yes, how could i calculate?

I attach the datasheet from Texas.
http://www.ti.com/lit/ds/symlink/lm2596.pdf

Original Topology from Texas
\

Edit: The objetive is to charge a battery pack of 3 Li-Ion cells efficiently, firstly mppt step is where my doubts are.


texts:
why common emitter configuration is used more than common base configuration of transistor for amplification purpose?
 when common base configuration provides more stability than of common emitter configuration


texts: Is the meshed metal cage connected to the earth terminal in these embedded power supplies?

texts:
The SMPS below has screw terminal mains entry as line, earth and neutral:

Is its meshed metal cage in general connected to the earth terminal internally? I could check it if I had one but at the moment I don't have such power supply next to me. I also don't see any indication in the datasheets.


texts: Why does smartphone GPS find its position much faster than a GPS module?

texts: When I'm using the arduino GPS module it usually takes a couple of minutes for it to start sending data. And it seems that it's usually the case with all GPS modules since they need to "listen" to the satellites for some time. However whenever I use my phones internal GPS it find its position in a matter of seconds. Why is that?


texts: I'm running a simple program on an ATtiny26l but if i disconnect my AVRISP MK2 programmer it stops working completely. I'm supplying 5.4v to both VCC and AVCC pins (chcecked voltage).If i reconnect the avrisp it starts working again, and it also doesn't work if the programmer is not powered. Reseting the MCU or power doesn't help it simply refuses to work without an active programmer.


texts: Systematic high frequency error in TF measurements

texts:
Full disclosure, I've asked a very similar question before which didn't have much success as it was too specific. However I want to try again by restricting the scope of the question.

Scenario

I'm performing measurements of a transfer function of a DAQ (NI USB-6251). I have placed 2 MΩ in series between the input and output of the DAQ:

simulate this circuit – Schematic created using CircuitLab

The output/input impedances in the above schematic come from the DAQ datasheet.

Due to the 100 pF at the input to the DAQ I expect to see a low pass filter with cutoff frequency at
$$
\frac{1}{2\pi (2\times 10^6)(100\times10^{-12})} = 795\ \text{Hz}
$$

Measured results

Fitting an RC model to the measurements I find the capacitance to be around 57 pF (1396 Hz 3 dB point). This then fits quite well to the measurements, up to about 10 kHz.

The question

Why at high frequencies do the measurements deviate from the model? Has anyone seen this behaviour before?

Edit

Below is the measurement with no R2, i.e. no 2 M resistor.  There still seems to be a deviation in amplitude and phase from the anticipated flat response. The amplitude response fits what is specified in the datasheet in Figure 2.

For reference, I'm using a sample rate of 1 MHz, am using a signal length of 1 second which is averaged 100 times.

Edit 2

I have updated my model: it now actually includes the 0.2 Ω output resistance, and now includes a parasitic capacitance across the resistor. Hand-tuning using the amplitude response, I found 650 fF to be a good fit, illustrated in the figure below. While the phase is over-compensated I am beginning to see that this is likely in higher-order parasitic effects as was mentioned by Daniel Turizo in my previous question. It does not look like it will be easy to get a perfect fit at higher frequencies, particularly because I am working on a breadboard...


texts: How does difference in loads affect current draw

texts:
This is a side question to 487370/limit-charging-current-to-a-smartphone. Hopefully it will clear the confusion in my head.

Say we start at 5.5V with a series resistor of 1 ohm, that will leave 5V for the phone and limit to 500mA. However if the phone tries to draw more the voltage will collapse, right? Why is that not happening with, say, LEDs? If you increase the resistance in series, the current decreases no matter how much current the LED wants?


texts: Battery charger/discharger using N mosfet only

texts:
I want to make a battery charger discharger with an arduino, to be able to plot graphs. And afaik N mosfets are better in terms of Ron and cheaper and easier to find. I have only N mosfets by the hand, so i decided to use only them, as a design restriction rule.

As a starting point i've opened a simple tutorial of charger, which offers following schematics:

Everything is transparent here: only one transistor, no magic with opening N-mos gate, and a 5V rail is constantly availble to Arduino.

However here are some drawbacks, that I dont know how to solve yet:

Major is that I totally stuck, trying to think of discharging circuit. I simply cannot short circuit 5V rail to the ground.
Minor is If 5V rail is disconnected from supply and charging is off there is no hope to start arduino from battery
Need to choose discharge current, I saw that variable CC-load is possible.

P-mos and changes to schematics could easily solve each. Is there a way to go for a design with N-mosfets only?

PS: Long ago, my math teacher used to say: "If it's impossible - why? If it's possible - how?", while posting an interesting task.


texts:
I would like to determine what is the worst case VCEsat at a certain collector current and a certain gate emmitter voltage of an IGBT. So I have to do a linear interpolation of the worst case output characteristics.

Here is the recommendation from the document above.

Nevertheless, I m not able to find the information of VCEsat(typ) and VCEsat(max) into the datasheet at the maximum temperature junction by supposing it is at the maximum temperature junction the disparity is maximal …

Here is the datasheet :

https://www.infineon.com/dgdl/Infineon-IGB20N60H3-DS-v02_03-en.pdf?fileId=db3a30432a40a650012a4677106a2b6d

Thank you very much !


texts: Constrain plane clearance from annular ring in Altium

texts:
I need to constrain a plane from shorting to the annular rings of a number of vias.

The dialog found at Rules and Constraints -> Design Rules -> Plane -> Power Plane Clearance  allows me to enforce a clearance from a via, but that clearance appears to be reckoned from the hole diameter and not from the diameter of the annular ring.

The following two screen shots show the effect of an adjustment to the Clearance parameter from 10 to 6; when clearance is set to 10, the actual clearance to the annular ring is only 5 mils:

But when clearance is decreased to 1, the plane nearly shorts against the annular ring with only 1 mil of clearance:

If every via shared the same annular ring diameter of 10 mils, for example, it would be possible to generate a single rule to give the desired clearance by simply adding 10 mils to the desired clearance.  However, some vias have larger hole diameters and annular rings; a rule that fit the smaller vias would short the plane against the larger vias, and a rule that fit the larger vias would leave larger clearances than desired around the small ones.

One way to accommodate varied via sizes would be to add all vias to a class based on their size, then add a compensated rule to target each class.  However, I'd like to avoid manually tagging thousands of objects into classes, and this work seems superfluous since Altium already knows the size of each object.

Is there a more succinct way to specify a uniform plane clearance from the annular ring of every via?


texts: design data storage using a simple MUX instead of a complicated SR latch

texts:
I was studying sequential circuits and I am at the very infant stages of the course. After studying the D flipflop I realized that the purpose was to let the data line change the output if clk=1 or keep the data same if clk=0. The circuit that is generally used is derived out of the SR latch which is a complex circuit using two feedbacks. Why cant I use a simple one feedback MUX circuit with the following boolean function?

Q(n+1)=Qn.C*+D.C

simulate this circuit – Schematic created using CircuitLab

The circuit diagram at the gate level would be as shown above, where D is the data line and C is the Clock. Am I being dumb somewhere??


texts: INA219 measure voltage of battery with RPi

texts:
simulate this circuit – Schematic created using CircuitLab

I want to measure voltage of 12V battery powering something by INA219 connected parallel to this battery and read it with RPi via I2C. Is this possible with INA219? Should I use something else for this? I tried to connect it like I imagine but I had to use 1K resistor between INA219 and battery and my reading then look like this:

Bus Voltage: 0.008 V
Bus Current: 12.305 mA
Power: 0.000 mW
Shunt voltage: 1.240 mV

This way Bus current looks exactly like my voltage provided on Vin

I tried connecting grounds from battery and RPi but there was no change.

Added schematic. Is it clearer now?


texts: Steps to hand draw Bode magnitude plot for a particular transfer function

texts:
Can anyone guide me through how to hand draw a correct Bode magnitude plot for

$$G(s) = \dfrac{48000}{s(s+0.1)(s+100)}$$

Don't even need phase plot, just need correct magnitude plot
As few calculation needed as possible, in other words, just use rules for poles and zeros (pole -> -20dB/Dec, zero -> +20dB/Dec) instead of calculating raw numbers

The MATLAB produced Bode plot can be seen here:


texts:
While working on a new design, we had to route Ethernet signals on our PCB. My colleague and I has some discussion on how we should handle the grounding around the Ethernet signals, and their return path.
The signals are routed from the PHY to the magnetics, travel some distance on the PCB, and exit through the Ethernet connector. Our discussion was for the part after the magnetics and up to the connector.
My colleague proposed that we shall add a proper ground plane under these signals, and pay attention to the return paths.
I, on the other hand, proposed that we don't need this, as the Ethernet signals are magnetically coupled, and essentially galvanically isolated. Its like having an unrelated cable just happening to be close to the PCB, without any actual electrical connection.
So, is it actually needed to have a return path for the Ethernet signals?


texts: Differences between Interrupts and sampling for hardware button?

texts:
I have a hardware button I connected to an interrupt, but my problem is it bounces a bit, making the button press unreliable. I think a good deal of these issues would be solved by sampling in the main loop, but that just feels technically wrong.

Are interrupts more appropriate for intra-circuit communication or are interrupts also appropriate for hardware switches? If so what debounce techniques can I use?

I've tried keeping a timer variable and checking it against current time, delays, and other techniques. It seems as if the bounces are just so fast it doesn't matter.


texts:
What can i do to minimize overshoot and undershoot when MOSFET switches on and off? (waveform taken using short ground spring probe, PCB is 2-layer) The rise and fall times should be less than 150ns.

Here is the picture without snubber (R1, C27)

I tried using snubber on mosfet drain (3.3R, 4.7nF). Overshoot is reduced but i don't like much longer risetime..

More about schematic: It acts like a function generator: You can control frequency and amplitude of pulses. Amplitude from DAC is mixed with square signal from MCU on MOSFET Q3 drain.When amplitude is about 2V overshoot is gone. It start appear only when amplitude decreases to less than a volt. In the pictures there is about 200mV of pulse.

Please suggest how to reduce overshoot and at the same time keep the edges fast (150-200ns). Thanks!


texts: Circuit protection problem driving high side MOSFET continuously

texts:
I need to drive a high side N-channel IGBT continuously.  The circuit is essentially a passthrough, and the only thing I want to do is turn this pass through line on or off (usually if not always on) using a MOSFET. The line is 500V and running around 20A.

Using an external power source of 15 volts to drive a FAN73711MX driver, will I still be looking at the Cboot discharging and causing disturbances in my power flow on the line, or will this work at a zero switching frequency.  If not what can be done?

Continued:
So I Have added a charge pump circuit to the design, as well i have switched from MOSFET to IGBT because it makes more sense.

At this high of a voltage I have not been able to find any other solutions to this problem.  Will this circuit work or is there another option that I should look into.

The power source is coming from an off the wall 15v supply, and the 500V lines are being stepped down from a PV array.


texts: FT2232H - FT245 Synchronous FIFO mode read timing

texts:
I'm trying to understand the read timing diagram of the FT2232H in FT245 Synchronous FIFO mode so that I can properly configure the state machine of the FPGA attached to it. Here's the datasheet page for the timing diagram (read timing upper half)

And the corresponding description.

This seems to indicate that the positive edge of CLKOUT sampling OE# low and RD# high reads the first data word from the RX buffer (assuming RXF# is low). In contrast, all subsequent data words are made available by sampling both OE# low and RD# low (also assuming RXF# is low).
Is this correct? Or, is the first word available after RD# is sampled low? Or, something else?
I feel fairly confident that the first option is right, but the read state machine does not work as expected so I'd like to be sure I didn't miss something here.
Can OE# be kept low if RXF# temporarily goes high, and then reads after RXF# returns low would follow RD# being sampled low?


texts: Best options for limiting input ringing with ceramic capacitors

texts:
Ceramic capacitors have this unfortunate property which can cause spikes in voltage when live batteries are connected to boards (hot-plugging), due to the inductance of the wires to the batteries and the very low inductance of the capacitors. It can create spikes of more than double the supply voltage.

On my first board which used entirely ceramic capacitors on the input, I read up on this in detail in the LT1933 datasheet (See page 14) and the recommendation was to use a 1 ohm series resistor, in a 1206 package, because it may dissipate up to 0.2W, and a 0.1µF cap directly on the input to reduce input ripple. However, I am now working on a project which has a 2A buck converter. That poor 1 ohm resistor, at a low input voltage, could be dissipating 4 watts! That is way too much.

The datasheet also recommends using an aluminium electrolytic capacitor, I'm currently using this. However, it is pretty big and ideally, I would like to eliminate it from my board. Also, being an electrolytic makes it sensitive to environmental conditions a lot more than ceramics, and it reduces the lifespan of the device.

So, what are my options for limiting hot-plug spikes?


texts: Capacitance detection circuit in LTspice

texts: I have designed a circuit to detect ice in software LTSpice. When I did ac analysis, it shows the gain is constant from 10KHZ to 10MHZ. That means, I can detect ice during operationg the sensor with these frequencies range. However, ice can be only detected at low frequencies. i.e 1Khz. So I want to make my circuit to works from 500Hz to 10MHZ. So I need ac response as flat with same circuit by making small changes. Please find the photographs and help me how to do it?


texts:
I'm trying to build a high speed counter to measure the time delay between two radio waves . I'm thinking of using a MC100EP016A counter which works at a maximum frequency of 1.4 GHz but I cannot find out a clock IC as an input to this counter .

It requires an input high voltage of 2075 mV to 2420 mV and an input low voltage of 1355 mV to 1675 mV . this input range is much above the LVPECL output range most voltage controlled crystal oscillators provide and I cannot find a LVPECL to PECL converter at 1.4 ghz.

What can I do?

or are there any alternatives?

please help ...


texts: STM32 reading data from digimatic SPC and communication via I2C at the same time

texts:
I am working on an application running on STM32, which aims to read data from the digimatic spc protocol (mitutoyo device) and then send the data to the raspberry pi via the I2C bus. The Raspberry pi is the master on the I2C bus and the STM32 is the slave.
STM32 reads the data from the digimatic protocol in a cycle. I2C in STM32 operates over an interrupt. So when a request comes from raspberry in STM32, an interrupt is triggered and serviced immediately. The problem is that reading data from the digimatic is interrupted, so bad data is sent via I2C. As soon as the program returns to the place where it ended before the interruption, the reading is already in another phase and the reading of the data is completed with an error.
Has anyone solved a similar problem?
Here is the code to read the data
int main(void)
{
  HAL_Init();
  SystemClock_Config();

  MX_GPIO_Init();
  MX_I2C1_Init();
  MX_TIM2_Init();

  HAL_I2C_EnableListen_IT(&hi2c1);

  while (1)
  {
      //reading data
      RQST_LOW();
      HAL_Delay(5);
      RQST_HIGH();
      uint32_t timeout=200;

      time=0;
      TIM2->CNT=0;
      HAL_TIM_Base_Start_IT(&htim2);

      for(uint8_t i = 0; i < 13; i++ )
      {
          uint8_t k=0;
        for (uint8_t j = 0; j < 4; j++)
        {
          while(HAL_GPIO_ReadPin(DG_CLK_GPIO_Port,DG_CLK_Pin) == false && timeout>time)
          {
              time=(uint32_t)TIM2->CNT;
          }
          while( HAL_GPIO_ReadPin(DG_CLK_GPIO_Port,DG_CLK_Pin) == true && timeout>time)
          {
              time=(uint32_t)TIM2->CNT;
          }
          bitWrite(k, j, (HAL_GPIO_ReadPin(DG_DATA_GPIO_Port,DG_DATA_Pin) & 0x1));
        }
        rawdata[i] = k;
      }

      if(!(timeout>time))
      {
          aTxBuffer[0]=' ';
          aTxBuffer[1]=' ';
          aTxBuffer[2]=' ';
          aTxBuffer[3]=' ';
          aTxBuffer[4]=' ';
          aTxBuffer[5]=' ';
          aTxBuffer[6]=' ';
          aTxBuffer[7]=' ';
      }
      else
      {
          HAL_TIM_Base_Stop_IT(&htim2);
          char buf[7];
          for(int lp=0;lp<6;lp++)
          {
            buf[lp]=rawdata[lp+5]+'0';
          }
          uint64_t cur_value_int =atoi(buf);
          char buf_dec[2];
          buf_dec[0] = rawdata[11]+'0';
          decimal = atoi(buf_dec);
          float cur_value = (float)cur_value_int*(float)pow(10,-decimal);
          char buf_sign[2];
          buf_sign[0] = rawdata[4]+'0';
          int32_t temp = atoi(buf_sign);
          if(rawdata[4]==8)
          {
            cur_value = -cur_value;
          }
          char buf_unit[2];
          buf_unit[0] = rawdata[12]+'0';
          temp = atol(buf_unit);
          units = (bool)temp;
          RQST_LOW();
          HAL_Delay(50);
          float nearest = roundf(cur_value * 100) / 100;
          char array[8] = {0};
          sprintf(aTxBuffer, "%.2f", nearest);
      }
      HAL_Delay(300);
  }
}

Here is the I2C interrupt handler code
void HAL_I2C_AddrCallback(I2C_HandleTypeDef *hi2c, uint8_t TransferDirection, uint16_t AddrMatchCode)
{
  UNUSED(AddrMatchCode);

  if(hi2c->Instance==I2C1)
  {
      if(TransferDirection == TRANSFER_DIR_READ)
      {
          if(HAL_I2C_Slave_Seq_Receive_IT(&hi2c1, (uint8_t *)aRxBuffer, RXBUFFERSIZE, I2C_NEXT_FRAME)!=HAL_OK)
          {
              Error_Handler();
          }
      }
      else
      {
          HAL_I2C_Slave_Seq_Transmit_IT(&hi2c1, (uint8_t*)aTxBuffer, 8, I2C_LAST_FRAME);
      }
  }
}

void HAL_I2C_ListenCpltCallback(I2C_HandleTypeDef *hi2c)
{
    HAL_I2C_EnableListen_IT(&hi2c1); // Restart
}

void HAL_I2C_ErrorCallback(I2C_HandleTypeDef *I2cHandle)
{
  if (HAL_I2C_GetError(I2cHandle) != HAL_I2C_ERROR_AF)
  {
      Error_Handler();
  }
}

I will be happy for any advice


texts: Ground Plane for Flying Antennas (literally)

texts:
I am building a weather balloon sensor baord with a LORA 868 MHz radio module (RFM95x). The sensor will rise up to 30km and should transmit the full time.

I am using a PCB trace antenna with ground plane. For ground applications it is fine to have the antenna on the upper side of the board.

My question A is if I should flip the board upside down to get the ground plane out of the way and have a clear view to the basestation?

Question B is if I flip the antenna (rotate the board), what happens to the polarizastion? Do I have to consider this in the trace (or basestation antenna)? Is this type of PCB antenna the way to go, or should I use an external (dipole) antenna?

Thank you for the help!

868 MHz PCB antenna like this:


texts: High Voltage Active Rectification using Silicon Carbide MOSFET

texts:
This is a purely theoretical question, please forgive me if I am being stupid.

Synchronous rectification and secondary side control of DC/DC converters is very commonplace in low voltage, high current applications because the MOSFETs can have lower voltage drops than diodes, meaning efficiency isn't deteriorated during rectification of the AC voltage. In high voltage applications, the DC voltage can sufficiently handle the voltage drops of the diodes without effecting the efficiency significantly since the drops are relatively small. Furthermore, MOSFET ratings mean that they cannot be used in kV range output applications.

Theoretically, now that high voltage rated silicon carbide devices exist such as the 3.3kV CoolMOS, could there possibly be any benefit to using active rectification/synchronous rectification in high voltage, low current applications? Possibly adding extra control in the secondary side may lead to tighter voltage regulation, or the benefits of topologies such as the dual active bridge can be realized in HV applications where the usually wouldn't have been?

Or would it be much better to just stick to silicon carbide Schottky diodes in the HV full bridge rectifier/multiplier, or even just good old silicon devices?


texts: need to to substitute 2 car batteries needed for 48v test voltage (guessing ~3A)

texts:
I plan to use Lithium Ion source eventually but need 48v working voltage to bench test my project (incorporates a leaf blower). I have 2 good car batteries but need to safely substitute the other for at least 40v.

Possible options I am pondering:

The 6 or so old batteries hold ~8-10v but I don't know how long.
I have a 12v supply for a trailer home that used to work fine but now needs repair.
I have an assortment of power supplies from computers etc. Can I wire groups of them in parallel?


texts: How in the world does this prank pen work?

texts:
Help here would be greatly appreciated:
This question has been asked several times on this site and elsewhere, and it seems as if the posters became satisfied with inaccurate answers.

How on earth do the electric shock prank pens/bubble gum work?
I have no intention of shocking anybody or recreating this circuit, I am simply baffled by how it operates. I have verified that all purported explanations readily available online are inaccurate or incomplete.

The above image shows the only two components in the circuit. I do not know for a fact what the white component is, but I have to assume it is a high value capacitor.

The above image is a literal layout of the circuit. The 50k load is the user's hand. Both switches are closed upon pressing the button. The switch is before the capacitor. This is based on closely observing the circuit and is 100% accurate unless someone can prove otherwise. I tested this with varying capacitance and inductance values and was unable to induce a significant current in the load for more than dozens of miliseconds. When testing I moved the virtual switches from the ground to the positive wire. When I move the switch after the capacitor I can have a long lasting current through the load, but the voltage/current are very low.
Edit: It is beginning to appear as if the white piece (Shown as cap above) is an active component/IC. There may not even be a capacitor in this circuit.

What I know:
1. The device behaves as follows: When the pen is held and the button is pressed a mildly painful electric shock is felt. After about 3 seconds, the pain gradually decreases until it is not longer felt. Upon releasing and pressing again the full shock is felt once again, even if only released for the slightest moment. The button and grip are the electrodes.
2. It uses 4 1.5V button cells in series (with high internal resistance)
3. The shrink wrapped component is a tightly wound step up transformer. The   secondary uses extremely thin wire. It apparently is an autotransformer, as it has three leads and is wrapped around one ferrite column.

What I think I know:
1. I measured the frequency on the primary with a primitive oscilloscope. It was equal to a couple hundred hz, which is reasonable considering the pain of the shock.
2. If the frequency is ~200hz, the capacitor (if the white component is a cap) would have to be over 100uF non polarized. This may be possible as I have discovered high capacitance low voltage smd caps. The primary inductance would have to be several mH.
3. The turn ratio would (I believe) have to be at least 1:90. This surprised me because I read that most autotransformrs have a low ratio. I then encountered higher ratio custom ones (which is more reasonable if varying wire gauges are used).

What I want to know:
1. What the white component is. Is it merely a capacitor? Does it serve other functions?
2. How on earth does this circuit work. It seems so simple and then again I can't explain or emulate its behavior accurately in a simulator...

Help will be greatly appreciated, as this has kept me occupied for a long time.


texts:
So I found a VGA to composite passive converter circuit online, and was wondering if it would work, if the vga timings were modified to match the timing of composite.

Here is a relevant schematic:


texts:
Basically the LTC3603 seems to have internally shorted itself. I'm using a auto generated circuit, realised with Eagle CAD.

I'm trying to design a high current switching power supply with the Linear Technology's LTC3603. I used the companies software tools to create the required circuit and used Eagle CAD to create the circuit and ordered up a test PCB.

When I received the PCB I first buzzed it out to check that the circuit was as I expected it. Then I soldered on all the components and again buzzed it out to make sure that everything as connected and that their were NO shorts. With that all done I connected the circuit to a desktop power supply giving about 12V DC to the circuit.

My circuit didn't work at all. The switcher just seemed to connect the input 11.7 Volts straight to the output without out ever switching. I was only turning on power briefly and taking measurements and then turning off power. I didn't get any burning but after a few of these measurement operations the LTC3603 seems to have shorted itself Internally.

I'd happily post my eagle files for the test design but not sure where to do that. I'm just wondering if anybody would recognise or suggest why the device seems to have simply shorted itself out? Obviously even though the circuit was not switching, it was wrongly supplying 11.7V output from 11.7V Input. Maybe that left the mosfets on too long in the chip so maybe my question should be why it never switched?

Data sheet example circuit - replace with actual circuit when available.

LTC3603 data sheet here


texts: Calculate inductance for 3-phase double ckt line

texts:
I have attached the problem with the solution given in my workbook. I attempted the problem and ended up getting a different answer.
Is my solution wrong ?
Please help me to understand the problem.


texts:
I'm making a system that is going to heat water in a 25 liter tank to a given temperature and keep the water on this temperature with a precision of +/-0.5 °C. As I have done some research I have decided to control the heating element with a zero crossing solid state relay and control this relay with an Ardunio. The heating element is 230VAC, 3kW.

My question is, for how long can I run constant current through the heating element without overheating it? I mean, if I turn the hot plate on my stove on max, will it run constant current through the element or will this still be pulses and how to determine the pulse width and time between these pulses?


texts: How to connect the Arduino with Twitter via GSM/GPRS?

texts: I know there are tons of projects that use WIFI or simple LAN shields to send sensor data from the Arduino as Twitter messages. How could this work with a mobile phone connection? Are there libraries or handware layers that enable TCP via GSM or GPRS? If not with Twitter, could I email the data or send to other APIs which would be HTTP requests?


texts: UPDATED:How to do Band Pass Filter Analysis for the current circuit

texts:
For the following circuit i am having trouble finding the following respective cutoff frequencies as i am unsure on if i need to take in to account R3 for the high pass portion. Also for the low pass portion do i need to take into account R1 and R2 or not as i know what Vin1 will be?

R1 and R2 are used as a voltage divider as Vout1 has to be less than a certain voltage due to the use it entering an amp after.

Hence what are the formulas i need to use to calculate the cutoff frequencies for say 15Hz - 50kHz? Can i just do for the highpass fc=1/(2pi*(R1+R2)*C)
and for the lowpass portion fc=1/(2*pi*R3*C)? To find Vout1 can i just do Vin1*(R/(R+1/jwc))?

Also the high pass is used to block the dc bias from the input.

Also so are R1 and R2 in series? Then if they are what is R3 in terms of R1 and R2 (as in parallel OR series configuration)

UPDATED:
For this given example when i analyse it like the the first plot it gets the correct cutoff frequencies that i am expecting. The problem is that i dont get how to calculate the resistor values for when the voltage divider is used. As it can be seen when i tried, the cutoff frequencies are not what i want and are far off. Hence what equations do i use to calculate R1,R2 and R3 as i assume for the second plot all resistors matter for each filter.
First plot gets 20Hz and 15kHz for the -3db cutoff however the second plot is around 20Hz and 5kHz?

Thus how i calculated the lowpass resistor value is wrong and was wondering what formula is needed for fc for the lowpass.


texts:
simulate this circuit – Schematic created using CircuitLab

i've searched but can't find a definite answer, is it possible to use the standard resistor divider but with a Zener in the middle to offset a Feedback voltage required for a Buck regulator IC? I'm already aware of the high current and stable LM317/337 combo for a mid rail, this uses a 2.5v Zener middle to obtain +-1.25v respectively for each regulator
After studying some active Lithium balancing topologies, i see circuits using tiny buck regulators for balancing every pair of cells, being a Shed hobbyist, i'd like to build a bigger & cheaper version... a bit of research brought me to the Mini360 which uses MP2307 and a V-ref of 0.925/1.1v to cycle the inductor.... so following the LM317/337 model, if i use a 2v0 Zener (BZX55c) between a pair of carefully matched 1% 1.2k R's, this should shift the voltage by 1v (approx) from center and the current across the resistor divider calculated for 8.4-6.0v and enough Ma for the stable(ish) 2.0v drop (1.2-2Mah for the Zener according to the datasheet).... am i understanding this correctly or am i going about it the completely wrong way?  i'd dearly love to hear your Fb on this. ;) Pun intended, thank you for enduring my first post.


texts: 50 ohms output termination for a 50ohms load?

texts:
Would the voltage measured at the 50 ohms still be doubled to the reading on the function generator?
I am new to the concept, from what I know, the 50ohms function generator outputs double the voltage if it is connected to a oscilloscope that has high input impedance. If now we were to use the 50 ohms function generator for a 50 ohms load and then measure the voltage drop on the load, would the resulting voltage still be doubled?


texts: Best most efficient motor type to be used as a DC generator

texts:
I'm trying to design a system that requires a very light weight very efficient generator to be used from converting rotational motion into DC voltage(for say charging batteries)
As far as I know BLDC's are the most efficient and light weight to convert the other way around electrical power to rotational energy

What would be the best motor type to be used in this app in term of weight and conversion power?(AC, BLDC, brushed DC?)

Thanks for helping.


texts: Is there any way to combine data with power?

texts: Imagine I have a standard TTL data signal and want to transmit that data along the same wire that provides power for the receiving device. Is that possible?


texts:
I am doing a test project to test the STM32's sleep mode feature. The project involves two microcontrollers:

STM32F411 with a push button, which when pressed, sends data through SPI to an STM32F303 microcontroller. This microcontroller is also equipped with an LED indicating that it has send data through SPI.
STM32F303 which receives the data through an SPI interrupt and a blue LED that blinks once it receives the correct sequence of data

I have implemented the SPI Interrupt Send/Receive successfully, and also sleep modes on both microcontrollers successfully with the following code:
int main(){
   ...
   ...
   /* Suspend Tick increment to prevent wakeup by Systick interrupt */
   HAL_SuspendTick();
   /* Sleep immediately after every successful interrupt execution */
   HAL_PWR_EnableSleepOnExit();
   /* Request to enter SLEEP mode through WFI */
   HAL_PWR_EnterSLEEPMode(PWR_MAINREGULATOR_ON, PWR_SLEEPENTRY_WFI);
   /* Resume Tick interrupt if disabled prior to sleep entry */
   HAL_ResumeTick();

   while(1){
      ...
      ...
   }
}

With the above code, I have verified that whatever happens in the while loop does not execute because both microcontrollers will only wake up when an interrupt occurs and goes back to sleep through the HAL_PWR_EnableSleepOnExit() (without this, the while loop will execute and sleep mode only occurs once). Furthermore, on the STM32F411, I also verified that it was in sleep mode by checking the current consumption through the IDD ports.
I am attempting a different method of achieving the above by manually placing the STM32F411 to sleep inside an ISR and omitting HAL_PWR_EnableSleepOnExit() inside the main function so it does not automatically sleep after the interrupt execution.
int main(){
   ...
   /* Sleep once until next interrupt occurs */
   HAL_SuspendTick();
   HAL_PWR_EnterSLEEPMode(PWR_MAINREGULATOR_ON, PWR_SLEEPENTRY_WFI);
   HAL_ResumeTick();
   while(1){
      ...
   }
}

With the ISR for the STM32F411 being:
void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin){

   if(GPIO_Pin == PushButton_Pin){
      /* Send data over SPI, where data is in pTxBuff and the length of data is cTxLen */
      HAL_SPI_Transmit_IT(&hspi1, (uint8_t*)pTxBuff, cTxLen);

      /* Enter Sleep Mode after interrupt execution */
      HAL_SuspendTick();
      HAL_PWR_EnterSLEEPMode(PWR_MAINREGULATOR_ON, PWR_SLEEPENTRY_WFI);
      HAL_ResumeTick();
   }

}

The method above does not work (only works with the first press of the push button on the STM32F411). Any reason why that is the case? I am planning to do something like this on a larger project, where the microcontroller sleeps until an interrupt occurs, then the microcontroller processes data in a while loop, and then go back to sleep until the next interrupt occurs.
Any help would be appreciated. Thanks!


texts: Determine adequate speed of flyback diode for a relay

texts:
I have already looked at this question which looked like it would provide the answer:

How to choose a flyback diode for a relay?

But it didn't, so I also checked out these:

https://electronics.stackexchange.com/questions/ask
Flyback Diodes and Relays
https://electronics.stackexchange.com/questions/163104/what-are-important-parameters-for-a-flyback-diode
Suppression diode for relays in ULN2803A
https://electronics.stackexchange.com/questions/136896/pwm-and-flyback-diode-dependency

Which didn't either. So my question is:

When selecting a flyback diode for a relay, how can I determine whether the speed of the diode is adequate for the application?

I am not looking for diode suggestions, but rather:

What specifications in the datasheet for a diode I would need to look at
How I can calculate the required values from 1. , given whatever information is needed about the circuit that controls the relay coil, and the specs of the relay.

I presume it has to do with capacitances in the diode's datasheet among other things.

Thanks

Edit: to clarify, I don't mind if the relay takes some time to turn off. What I am concerned with is ensuring protection of the controlling circuitry from the spike the coil generates when current to it from the controlling circuitry ceases.


texts: Old cellphones versus new cellphones noise

texts: Why older cellphones cause impulse sounds in our loudspeakers, but new cellphones not? Why these impulse sounds can be heard in our soundspeakers?


texts:
Bode Plot

1) Why the gain plot |G(jw)| drops and then increases for conjugate zeroes ?

2) Why the gain plot |G(jw)| increases and then drops for conjugate poles ?

Nyqust Plot

3) For Figure 9-18(B), could anyone explain in a bit more details than the book as on how to obtain the following Nyquist plot pattern ?


texts: Texas Instruments Schmitt Trigger inputs

texts:
Hi I want to use the TPIC6C595 in some project.
Because my application needs to be very noise insensitive I am wondering whether the shift register uses Schmitt Trigger inputs for G, SRCK, RCK, CLR, SER IN.
But after looking at the datasheet I could not find any information about that.

How Texas Instruments marks the type of inputs?