texts: On-board st-link programmer on F411 Discovery board cannot connect

texts:
Backstory:
I have STM32F411E-DISCO board which has on-board st-link which i used before without problems (also programming external stm's). Today i tried to program STM32F103C8T6 with SWD connector (CN2) on Discovery board without success.

Problem:
After that i put jumpers (CN3) back to connect with STM32F411 and it refused to connect with error "STLink USB communication error"  in ST-LINK Utility which never happend before (for F4).

What i checked:
I've already checked diodes D3 and D1 voltages and seems correct, LEDs LD2 and LD1 are bright red. Programing ic seems not damaged because despite of getting  little warm after while (but not really hot), ST-Link Utility returns its serial number and firmware version but fails to detect stm32 target.

Im bit confused because it looks like programmer is fine but still fails to connect any stm32. What should i check to identify source of error and possibly to fix it?

Edit 1: After some digging i found trace.log, it confirms detection of st-link and after second try to connect gives some usb error.

Edit 2:
After more extensive search i found out that when st-link tries to connect, SWDIO actually works but nothing is sent because SWCLK is always pulled low, and do not send any clock "pulses". Im guessing that my ST-Link SWCLK pin is burned and is hard pulled low.
Also checked target and it seems ok, another ST-Link connects to it just fine.
Last question, is it possible that anything else could be burned instead of pin?
 Because im looking in schematics (page 29) and i do not see anything bringing me hope.


texts: Current Regulation in LED Driver and PFC Circuit

texts:
Datasheet: http://diodes.com/datasheets/AL6562.pdf

I am trying to understand how this IC works block by block and I am confused about over-voltage protection in the error amplifier - specifically how it will work when I'm regulating current and not voltage. Unfortunately, the datasheet does not specifically talk about current regulation and instead talks about voltage regulation when it comes to the error amplifier, naturally fed by a voltage divider.

If you look at the linked schematic, R4 is the input to the error amplifier. From the schematic, I think it is easy to see that this there to regulate the current. My output current is 50 mA and the error amplifier's reference is 2.5 V, therefore R4 should be 50 Ohms.

The datasheet talks about over-voltage protection (OVP) in this section (Page 10). It states that for OVP, the IC monitors the current into the COMP pin and if it exceeds 40 uA, it will trigger the OVP. As 40 uA is the current threshold, this is used to set the voltage threshold via the voltage divider like so: dV/40uA = R
My question is, if I am using the IC to regulate current and not voltage how would OVP behave?


texts:
I've been asked to use the ideal diode model on the circuit below to determine the values of I and V.

To determine which diodes were on or off, I considered each possible case:

D1 and D2 are both off. This can't be the case because when both diodes are off, they each have positive voltages applied to them which would indicate that they should both be on. This contradicts the original assumption.
If D1 and D2 are both on, I get that V = 0V and I = -0.25mA.
If D1 is on and D2 is off, a positive voltage is applied to D2 meaning that it should actually be on.
If D1 is off and D2 is on, I get V = -1V and I = 0A.

Which one's correct? Case 2 or case 4?


texts: Characteristics of built-in Zener protection on FET gates

texts:
A lot of SOT-23 FET gates have built-in back-to-back Zener diodes to source, presumably to protect against over-voltage. However, the datasheets typically say nothing about the characteristics of these diodes. The gate leakage current will be much higher in FET's that have this structure (compared to those that don't), but otherwise the datasheets are silent about it.

One example: Diodes, Inc. p/n DMP10H4D2S-7.

http://www.diodes.com/_files/datasheets/DMP10H4D2S.pdf

I am designing a circuit where I am installing external back-to-back Zener diodes to protect the FET gate under certain conditions. But I am curious if I really need them or not. It seems to me that if I limit the current sufficiently, the built-in Zeners should protect the gate.

If anybody has any thoughts on this topic, I would be very eager to hear them. I mean, the obvious thing to do is just add the external protection to be safe. But I still want to know if anyone has any insight on the built-in protection.


texts: Injecting UUIDs into ROM during production

texts:
I'm brand new to electronics and was wondering if someone could explain to me how individual MCU/MPU-powered electronics units can be assigned unique identities on the factory line.

For instance, lets say a particular device is being built. This device has an MCU/MPU (still don't fully understand their difference) that has a CPU, ROM to hold a binary/RTOS and RAM for running that binary at runtime. A control program is flashed to the ROM at some point during production.

Say this device has the need to be given a UUID that can be read from memory when the control program starts up. Obviously, each device needs a different (unique) ID. And so I would imagine that the MCU would undergo two different phases during its production build: an initial flashing of the control program to ROM, followed by a second flashing that "appends" (without overwriting, that is) a device-specific UUID to a specific address in ROM. The control program would then be hardcoded to look for the value (UUID) stored at this address at startup.

Am I on track here, or is there a more efficient/different/standard way of accomplishing such a task? And I guess I would generalize it beyond a UUID and ask the same question of any situation where all units share a binary (the control program) but then also have their own unique information that must be present in ROM at startup.


texts:
My situation is as follows, I have a robot that has 4 motor controllers attached to an arduino that has a xbee series 1 connected. Xbee has its default settings except baudrate which is set to 57600. My communication with the arduino is one way from pc to arduino sending 5 bytes every 40 milliseconds (one byte for command 4 bytes for 4 pwms). All calculations are done on the pc, all arduino does is read these bytes and apply pwm values to pins. Robot is never more than 10 meters away from the transmitter, nothing in between.

What I am seeing is sometimes even though I'm sending a motor commands the solenoid on the robot triggers I'm guessing some packets got lost and the next byte on the stream is equal to a solenoid command.

What I am trying to do is something like UDP where I can just send commands and any command that is send while arduino is processing to be discarded basically every-time I read a command from xbee I would like to get the newest command send from the pc? Is there a way to achieve this?


texts: Level-Shifter, a resistor i dont understand

texts:
I got a lot of help in understanding this circuit in a previous post.

I just don't understand the choice of R3 or why it is even there exactly.

EDIT: I just read my question and realized I give no context at all.
This is supposed to be a levelshifter from 3.3V to 5V the Output requires near 5V for High and near 0V for Low.

Why is R3 1koHm?
Is it to limit the current to the output although I though a digital input has negligible current draw? Or is it just cause I need something to create a voltage drop and i don't care about the current anymore? Or is 5mA just a standard for digital signals?

simulate this circuit – Schematic created using CircuitLab

Thank you guys alot


texts:
I would like to ask for some help regarding a stepper motor I would like to use. I need 1 deg step and as I have seen there is no such stepper. Could you advise me as an amateur the way i could bring this down from 1.8 or bring t up from 0.9 .
What is easier and less complex?

Thank you,

John


texts: how to tag and find objects using wireless technology

texts:
I am not sure if this is the right forum for this question, If not please help me move it to the right place :)

Question: I have 10-20 items like tables / books in a room and I want to put a small self powered chip on them (solar / battery) that i can use to track their position from another room (say 100-150 ft away), Is there any such module out there that i can use.

Like for instance say bluetooth / IR, I can have a tiny bluetooth / IR module attached to them and use my phone / Laptop to track / ping them. (bluetooth is for data transfer, all i want is like a homing beacon that just points its location)

If pointing location is a problem then it should just buzz it / turn an alarm when i try to locate it...

The key focus points are:

1) Size (smaller the better)

2) Power requirement (if can be powered by a button cell that can last say 6 months)

3) Cost (cheaper the better)

Thanks.


texts:
I'm using 555 timer in astable mode. I've used Multisim to generate it ant this is what I've got:

I'm little confised by the 100 ohms Rl resistor. Do I need it there ? If I do, why ? I've tried with and without it, and it works for me both ways ... I'm using the 555 to drive another CMOS IC input.

Thanks


texts: Best practice: Should I charge a battery while also pulling load?

texts:
I have an off-grid solar panel setup. The solar panels send current to an MPPT charge controller. The charge controller controls current to a lead acid battery. On these same battery terminals I have wires leading to my load, an inverter and then AC compressor/motor.

I’m most concerned about the absorption charge phase, when it dumps most of the current into the battery at an elevated voltage. My controller operates in the absorption phase for 3 hours. It then drops into the float stage sending current at a lower voltage.

Should I avoid pulling load from the battery during the absorption stage so that the battery receives all of the current during this crucial phase?  I worry if the load is also pulling current during this time that the battery will enter the float stage not having fully recharged.

My goal is to maximize long term battery capacity, through shallow discharges and daily (full) recharges.

# Update

Some people raised some very good questions/comments.  I'll add some more details here to give a fuller picture.  And yes, because this is an off-grid solar setup, the variability of the weather/elemeents make it hard to say with certainty that there will be enough sunlight to complete the absorption phase uninterrupted.

Here's a
diagram
of my setup.
I have 2 100W solar panels (200W total) wired in series.
I have 2 55Ah AGM batteries wired in parallel.
I use this charge controller
I use this inverter
I use this compressor for pond aeration in 10ft of water.

On sunny days I’ve measure the voltage from the combined solar panels totaling 45V. The absorption phase charges the battery at 14.8V. The float phase is at 13.7V.

From my calculations I can only run the compressor for 4-5 hours before depleting the batteries to 70% of their capacity, which is the lower limit I’d like to sustain.  I was seeing if I could maybe cheat and run it a little longer once the sun came up. From some of the answers it seems like that may put the battery at risk of not fully being recharged daily.  I’m not sure it’s worth the risk


texts:
Here the situation.
I have 2 fans controlled by 1 PWM signal. Works perfectly like that.

Now, I want to trick one to be always 40% ahead of the other (and mechanically, have a minimum speed of 40%).

so for instance :

PWM signal is 20% : Fan 1 goes at 20% of the speed, Fan 2 goes at 60% of the speed
PWM signal is 40% : Fan 1 goes at 40% of the speed, Fan 2 goes at 80% of the speed
PWM signal is 60% : Fan 1 goes at 60% of the speed, Fan 2 goes at full speed
PWM signal is 80% : Fan 1 goes at 80% of the speed, Fan 2 goes at full speed

Any idea of a circuitry that could modify the PWM signal for my fan 2?

I do not need it to be perfectly accurate on the percentage,even if the added value fluctuates between beginning of the scale and end of the scale, that would be OK.


texts:
I have a reset bridge in VHDL which is based on a multi-FF synchronizer chain as depicted below. This reset bridge is used in various instances throughout my design.
I want to properly constrain the path to the asynchronous clear port.

Constraint:
set_max_delay -to [get_pins -hierarchical *i_reset_bridge*|s_rst_sync_FF[*]|ACLR] 10.000

Quartus tells me that it cannot find any matching pins:
Argument <to> is an empty collection

Any hint on how to get my sdc running?


texts:
I'm using a Microchip PIC18 and I need to use matrices in my code. I know DSPIC do have matrix libraries, that simplifies the implementation.
Does anybody know whether any is available also for the 18 family (my present PIC18 embeds an hw multiplier)?

Thank you all!


texts: How often are inductors used in electronics

texts:
I am a relative beginner at using electronics, and am tight on money for my first load of electronics that I am going to buy.

I was wondering if I should get some inductors now or wait for a bit later when I need them.

In other words: Are inductors used frequently enough to warrant buying a couple in advance?

Also, important to note: I live in a rural area, and the nearest RadioShack is at least a 45-70 min drive away, and I do not have legal access to a car (I’m under 16), so I would have to wait on delivery from Amazon or Adafuit.

Thanks for any help! Have a good day!

P.S. I have no projects in the near future that will likely need an inductor.


texts: Is my oscilloscope affecting my tuning circuit?

texts:
I am building an AM Radio and I have constructed a tuner circuit. See below.

simulate this circuit – Schematic created using CircuitLab

However, I cannot use this circuit, because even though in my calculations it works, I am not able to see the signal for the 570kHz band when it's connected to the oscilloscope. The 570kHz band will only show up if I drop my inductance down to about 250 uH. To me, this doesn't make sense and so I'm trying to track down the culprit.

After finding the band 570kHz, I measured the capcitor and found that my capacitor was set to about 234 pF.

Thinking this was odd, I put my LCR meter to the inputs of the oscilloscope and found that it has an inductance that fluctuates from 1000mH to 2000mH.

Is my oscilloscope affecting my tuning circuit, or is there parasitic capacitance somewhere in my circuit that is affecting it?

I want to be able to use the circuit I've described here so I can get a better band pass filter (I want high L and low C).

Details:
- the oscilloscope I'm using is an Iwatsu SS-5702 oscilloscope -- quite an old model
- my inductor is hand made and measure to be 1960uH
- my antenna is just a piece of wire
- I'm using a spring board to connect the parts


texts: How to connect a second battery to my UPS?

texts: I have a UPS, its battery seem to be dying. Earlier it was giving a backup of 30 min, now it has come down to 10 min with the same load. I purchased a battery of the same capacity 12V 7amp, I was thinking of connecting this one with a 2-way switch, so I can use both batteries by switching it when one gets discharged. Is this a right thing to do, will it create a problem?


texts: The effects on torque/slip when changing speed?

texts: I know that the number of poles altering frequency and voltage changes the speed but I don't know how either alters the torque or slip.


texts: What are the rules for combining transistors to form digital circuits?

texts:
I just read Harris/Harris - Digital Design and Computer Architecture and in it they described how AND/OR/etc gates are made out of transistors. I read the book for fun (I'm not an EE person, my experience with circuit analysis is minimal) so while I can understand how their circuits work to make the specified gate, I'd like to be able to make my own as an exercise.

In my mind I picture that a NOT gate should be as simple as the input connected to the gate and the output connected to the drain of a P type transistor. It "defaults" to on and when voltage goes up on the gate it cuts off the voltage in the drain. But the book illustrates both a P and N type in series, with the input connected to both gates, and with the output between the drain of the P and the source of the N. So that makes me think that there are some rules about what the gate, source, and drain can be connected to in order to have a working transistor.

So is there any general/simple set of rules for beginners on how to connect transistors into working combinational logic units? I'd like to do this as an activity with someone who knows almost nothing about circuit design (no knowledge of KVL/KCL etc) and as I won't be designing any actual circuits I'd rather avoid studying hard on circuit analysis. Can it be boiled down into a list of rules that I could explain to, say, my grandmother?


texts: Difference between a constant DC and PWM

texts:
I was wondering what would you get on subtracting a 12V (From 0 to 12V) PWM (50% duty cycle), from a 12V constant DC source?

I am sorry, english is not my first language. I mean that if from an arduino or a comparator, we connect the output pwm to a motor, and other side of the motor to a 12V source, then what kind of voltage drop can we expect across the resistor.


texts: My dad is working on a power supply device and happen to come across a MOSFET,  I apologize but I do not have much knowledge of electronics, which is labelled IRF150M. He knows the voltage and current rating of IRF150N which is 100V and 42A - as far as I remember. He does not understand English so he asked me to search the internet, but I could not find any datasheet related to IRF150M. Although, from a little guessing I told him that its voltage rating will also be 100V and current 38A to 42A, but he said that its voltage cannot be 100V based on a test he did. Can anyone tell me the voltage and current rating of IRF150M?


texts:
I have a question regarding simplifying a circuit of a function below that has 5 logic gates in original.

f = (A + B) * (C + D) + (A + B) * (C + D)' + C

= (A + B) * ((C + D) + (C + D)') + C

= (A + B) * 1 + C Complement

= (A + B) + C

Now, I have reduced to 2 logic gates from 5. But, here, am I allowed to change (A + B) + C to A + B + C, so that I can reduce number of gates (i.e., 1 logic gate) even more? If I am allowed, is there a name for this process (what kind of law is this)?

Thank you in advance.


texts:
How do I measure ampacity of conductive tape? I  want to replace a wired battery to equipment connection with copper adhesive tape because I need a very low profile on the connection.

The maximum current will be 200mA, max voltage 14V. Would standard copper adhesive tape be capable of carrying this current? Length of connection will be 4cm, width of copper tape track will be 1cm.

Like this one for example: https://ie.farnell.com/3m/1181-12mm/foil-shielding-tape-adhesive/dp/1653450?st=copper%20foil%20tape


texts: What causes the voltage drop in a realistic voltage source when the load current increases?

texts:
The realistic(practical) voltage source is modeled as an ideal voltage source plus a series resistor R in the above figure. In an ideal voltage source whatever the current load is the voltage would remain the same.

Apparently in a practical voltage source when the load current increases the imaginary series resistor will cause a higher voltage drop.

I think the wire resistance between the source and the load is not the issue here, since we are talking about the voltage change accross the power-supply terminals.

My question is then: What is this series resistor in a power-supply? What causes it to exist? Is that the change in Thevenin equivalent resistor?


texts: How does relative permittivity decrease with frequency while capacitance doesn't?

texts: As I understand, capacitance is $$\frac{\varepsilon A}{d}$$ where ε is the absolute permittivity. If the capacitor's dimensions are kept constant, then a change in ε with frequency should mean a change in capacitance (?). So why do they say capacitance isn't affected by frequency (but rather capacitive reactance)?


texts:
I'm still really new to electronics. I'm trying to get used to reading PCBs and what not. I just got a new multimeter and I wanted to test it out so I was using the continuity test on the board's copper traces. But what's really weird is it was saying that a point on the trace isn't connected to another point on the same trace. To clear up what I'm trying to say, here's a pic:

The multimeter's continuity test says the connection between A and B is open. I also measured resistance and it said it was infinite. To be sure it wasn't the multimeter I tested it on the below strips of solder and the continuity test said it was connected as it should.

So am I completely misunderstanding how these PCBs are made? Is there some kind of coating on the top of the traces that I can't see?

Thanks a lot,
mikfig


texts: Electric fence charging of peripheral devices

texts: My game electric fence is split into various sections in order to create redundancy.  Is there any design that I can charge a battery along the fence line from the joules generated from the line but not lose too much of the current in the fence line itself ?  These batteries will  either power lights or cameras or sensors to enhance my security.  It doesn’t need to be a commercial product; I am willing to experiment and build a prototype.


texts: Arduino RFID reader and pin current sourcing

texts:
I'm thinking about building the DIY RFID reader described here http://playground.arduino.cc/Main/DIYRFIDReader, with an arduino uno.

For the LC filter, I have a 330uH inductor at home (and I'm using a 4.7nF capacitor for C1 instead of the 7nF shown on the schematic, to get at 125khz resonant frequency) and also I'm using 1N4148 diodes instead of 1N914 (I couldn't find them on stock at the local electronics shop).

I did the simulation of the circuit in LT Spice (schematic is quite similar to what the original author has) and it shows we that the current draw from the arduino pin D9 goes up to 400 mA, from what I know the AVR can't source more than 50 mA per pin.

Here's the LTSpice circuit:

And the simulation result:

My question is: what will happen in reality when building the circuit, will the pin source less current than the simulation and it will simply work or I run the risk of damaging the pin by attempting to source that much current (perhaps not instant damage, but long term) ?

If there is risk for damaging the pin, what solutions do I have to prevent it? Would a simple current limiting resistor do?

Would it be better to use a push-pull configuration like the one below ?


texts: Measure resistance value between all nodes in a 3x3 resistor grid

texts:
I have a Schematic like that:

(except the power supply is an Arduino Uno with a voltage divider to measure resistance between any pair of ABC and 123, except C3 of course)

How can I get the resistance between all nodes (the resistance of every single resistor) in the grid, when I only measure between ABC and 123? All resistors are unknown.


texts: I want to put my led strip in my PC and control it with Arduino or ESP. Since led strip has 60 leds it's going to draw ~3.5 amps. I'm asking if anything would happen if I connect led strip to 20 amps molex cable of my PSU? I am already writing my code, and this is the only thing that I'm interested in. Thanks!


texts:
For some reason low voltage, high quality audio interconnects seem to be made of 3 wires braided together, when normal low voltage audio wires are two wires surrounded by a grounding sleeve.

I'm a college student, and I think I understand exactly how both of these methods can cut down on "internal" interference, but if I'm correct then the braided wire method wont do poop when it comes to helping block external magnetic field, which is why the grounding sleeve is great because it acts as a Faraday cage around the signal bearing wire.

Is there something that I don't understand about braided wire that is somehow magically better than protected wire for carrying an analogue voltage?

So I guess my question is: why does a cable that looks like this...

Cost more than a cable that looks like this...


texts: Quartus II - Can I include other files into a *.qsf file?

texts:
An Altera Quartus II project consists of one *.qpf and one or more *.qsf files. The qsf seems to be a TCL script like other EDA related settings and config files (e.g. xdc, sdc, ...).

Is is possible to include other TCL scripts into the qsf?

I don't like the idea of storing all design settings in one file (source files, pin assignments, ...). Like in ISE or Vivado, I would like to store e.g. pin assignments in seperate files and included them.

Excurse ISE:

ISE uses UCF files to store constraints for pins, placement and timings. It's possible to add multiple ucf files to one project. E.g. a GPIO.LED.ucf or a Clock.SystemClock.ucf.

Excurse Vivado :

Vivado stores constraints in xdc files (Xilinx Design Constraints - a Xilinx extended version of SDC files - Synopsys Design Constraints). XDC/SDC files are TCL scripts. Quartus also uses SDC files.


texts: Load cell amplification circuit operation

texts:
Here's the reference circuit for amplifying the signal from a load cell with precision OPAMPs as per the MAX44248 datasheet. Can this OPAMP circuitry be explained please. What's the relation between the difference of the two load cell terminals (Vcell) and the ADC differencial input (Vin+ - Vin-)?

Thanks!


texts: Difference between driver and transistor

texts:
I asked a question earlier question, "Is it safe to run Logic ICs at their maximum output current?" asking if it was safe to run logic ICs at their maximum current.

From what I understand, this is not a good idea and instead I should use some sort of 'driver' between my logic system and my displays.

After some searching I found the SN74HC244N however, this only has a maximum output current of 6mA at 5V (unless I'm reading the datasheet wrong). This doesn't seem very high to me for a 'driver' IC.

This got me thinking as to why I would want to use one of these chips as opposed to 8 transistors (which I assume could handle higher currents). Is it just ease of use that they are already in one small package or is there something I'm missing here?


texts:
It's been a while since I've touched electronics, so bear with me :)

Since I can not attach DTMF tones to an on-going phone call (https://stackoverflow.com/questions/16949867/unable-to-make-a-call-from-service), I had another idea.

If I modified a set of headphones (that have a microphone), would it be possible to directly output the speaker audio from an earpiece to the microphone and get decent results playing DTMF phones from the phone?

Android has a buit Tone Generator, so I can play DTMF tones to the sound output programmatically.

If I have to, I can fallback to SMS, but I'd have to have more logic in place for managing the 5% failure rates.

Any suggestions?


texts: Interference beetween on my board when shutting down a light on mains supply

texts:
My board is connected to mains supply throught a 220v/12v 15A adapter.
It features 4 stepper drivers L6476, USB / ftdi and ethernet connectivity (wiz850io), microcontroler
is stm32F4.
It's a 4 layers PCB : signal/ground, ground, power supplies, signal/ground.
12v is regulated to 5.5v by LDO and 5.5v to 3.3v by LDO too.
My workbench (so, nothing to do with the board), is lighted by some WS2812/arduino/220V->5v converter bundle.
When I switch off the lights of the bench (basic rocker switch), something happens on the board (reboot or crash).
Unfortunately the board is not at home now and I can't do any measurement for now.
But, I would like to know if it is a recurrent problem, if it is more likely to be something on the power supply or an EMI issue.


texts: I am trying to change the CAN cables alone to Cat 6 cables (which has 100 ohm characteristic impedance). The existing cable has 120 ohm impedance. By making this change to Cat 6 cables, I am trying to find out if there would be any issue with CAN signal integrity because the PCB transceivers remain the same with 120 ohm terminations in them.


texts:
I've been to a couple introductory Altium trainings and everything goes fine and dandy. This is the actual first board I am working on by myself. I've been learning so much just by doing stuff myself but there is something that I can't seem to quite understand.

Whenever I transfer my schematic to the PCB is is placed inside this reddish box, I believe it is a Room. All the examples I saw during training didn't do this. And if I move the components outside the box they turn green (DRC error maybe?)

Does anyone know what this means?


texts: Changing frequency of 555 timer with varicap or capacitor

texts:
I have created a 555 oscillator circuit where the output is set to have flashing LED light. Now I have a problem when I change the voltage of the potentiometer, the output frequency does not change. Here is the schematic of my circuit that I implemented in breadboard.

I used fixed ceramic capacitor of 10nF instead of varactor here for now. But If I change the capacitance and add 0.33uF, the flashing of LED doesn't change. Now LED only flashes with constant frequency. When I change potentiometer, I checked with multimeter that the voltage changes. I want to control the capacitance through the potentiometer so that the output frequency changes and LED flashing rate changes according to the changing of capacitance. Can anyone help me what is the problem here?

Components:
CMOS 555 timer
R1 = 1 kΩ, R2 = 4.7 kΩ, C1 = 10 µF and C2 = 0.01 µF
1 MΩ Potentiometer.


texts: What battery should I use to wire a 3V LED

texts: If I do not want to use any resistors, is there a battery that I can use to wire just 1 3V LED?


texts:
I have a circuit that draw 150 ma and i use 6V/4Ah dry cell to supply. Voltage regulator of this circuit needs minimum 8V so I use boost converter to draw the battery voltage to 8 volts.This converter works up to 2 volt.

 I would like to stop this module when battery goes below 4-5 volt. I tried this circuit with converter.

It worked but when i connect the converter to system the input voltage of the converter is decrease and converter is not work even battery at 6V. I would like to learn why this circuit not worked and what can i do to work this circuit for cut off the voltage under 4-5 volt.


texts:
I have the sequence: 0-3-1-2-3-1.
Making the table for this.
|Present state    | Next state | D1| D0 |
|  0    0         |  1   1     | 1 | 1  |
|  0    1         |  1   0     | 1 | 0  |
|  1    0         |  1   1     | 1 | 1  |
|  0    1         |  0   1     | 0 | 1  |
In kmap i get :
D0 = ~Q1 + Q0.
D1 = ~Q0 + ~Q1.
But, my sequence is incorrect when I set up the circuit. What was my mistake? Thank you in advance.
*I don't know if I was clear on the issue, but the image of the sequence


texts: Working Voltage for Basic/Reinforced Isolation (ACS712)

texts:
I'm planing to use current sense chip ACS712.
I don't understand some values in its datasheet, page 2 (Isolation Characteristics).

I understand "Dielectric Strength Test Voltage - 2100VAC" - that is isolation between pins 1-4 and 5-8. Pretty clear.
But what mean these values?

Working Voltage for Basic Isolation - 354 VDC
Working Voltage for Reinforced Isolation - 184 VDC

I'm planning to use it to measure current in mains (230Vac) and I'm really confused with those parameters.


texts:
I am having a really hard time finding anything on the internet involving DIY composite video.

I can find multitudes of "Adapter" projects like VGA to Composite, S-video to composite ect... but no "how to generate a simple analog video waveform that my tv can understand."

I want to eventually design a circuit that amplifies guitar input and "converts" it into a analog video signal.

I feel like this could be an interesting project that could help others understand how signals work. I first need to learn how composite video works and I need somewhere to start, Any thoughts?

Thank you.


texts: Vias without annular ring on internal layers, non-functional pads in a via

texts:
My PCB layout package (Altium) has an option to define the full stack of a via so one may have different sized annular rings on different layers.

I was wondering if it is considered "manufacturable" if a via has annular rings only on layers where it connects to other copper. On layers without connection (passthrough), may have no annular ring, just the plated hole. I understand this this is more of a question for a board house, but i was wondering what the general opinion on this is.

The motivation behind this question is that in very high density designs, it may be critical to have less clearance on an internal GND plane for example. The lack of the annular ring would be of great benefit as it would reduce the area the via needs to pass hough the internal GND plane.

Thanks in advance.


texts: Input/output for buck-boost converter controller implemented with FPGA

texts:
I am trying to implement a voltage controller for a buck-boost converter using FPGA. The control method I'm trying to use is in this paper:

www.engr.iupui.edu/~aizadian/index_files/Papers/C-28.pdf

The control diagram for the converter (plant) is below:

Plant and compensator equations from the paper:

The basic idea is that if the converter's transfer function is given by Gvd(s),
then the compensator's transfer function is given by G1(s) - Gvd(s)
so that in the result, which is their sum, the plant's transfer function (which is unstable and hard to compensate in series) is cancelled, leaving a conveniently stable transfer function.

As I plan to implement the parallel compensator within the FPGA, I think I can enter the feedback output voltage through an ADC, arrange the reference signal internally and output the control signal from Kp through a DAC.
My doubt is about the right addition block in the figure.I'm not sure about how to add the compensator's output to that of the converter.

A friend of mine suggested that the sum of plant and compensator outputs would be needed only as input to the feedback block and that the output quantity(here, voltage) would be simply the plant's output. I'm tempted to believe this is right, but it would certainly change the control diagram..

Can someone explain how the this system should be implemented? Do I have to do something like give the compensator's output (from within FPGA) to a DAC and add that with the plant's output voltage, or is my friend's way more correct?


texts:
I just found a broken "laser projecting alarm clock". I took it apart, and am interested in only the laser projection arm. This consists of a laser diode (although I suspect that this is actually just a normal LED), a small LCD screen, and a plastic lens, which can be moved for focus. The LED has two wires. The LCD has 12 wires, which are connected  more or less directly to the unit's microcontroller (a couple appear to have a single capacitor or resistor in between). The IC has an enamel blob and no markings. LCD wires are marked C1, C1, C2, and then S1 to S9. The board appears to be mostly running at about 3V (batteries are all 3V or 3.7V, and it has a 3V DC input).

The laser projection arm looks like a useful device. Since it can project time, then I assume it has at least a 3.5 digit 7-segment display (18:88), but the unpowered LCD just looks semi-transparent and green, and I can't see any markings. I would like to be able to use it for other projects, but I'm not sure how it works, nor how to start figuring it out. I have looked for data sheets of LCDs, but haven't found anything similar. I have a Arduino Leonardo, and was thinking of using it to figure out how the LCD is controlled.

So, a few of questions: Is the c1-3, s1-9 pinout common? Is it likely that the 5V from the Arduino could damage the (presumably) 3V LCD? What might be a good way to probe the functionality of the LCD?


texts: Influence of NFB on the Gain of Amplifier

texts:
NFB is an acronym for negative feedback.

Lets say that we have an amplifier with three stages: input (differential) stage followed by voltage amplification stage and output power stage. And we have a NFB from output of the power stage back to the differential input stage of the amplifier.

Will the open-loop gain of an amplifier decrease as the portion of global NFB is increased?
Referring to the lower graph: With 100dB of gain, the amplifier has roll-off point of frequency at 500 Hz. If we would decrease the gain of the same amplifier, would we also increase the roll-off point of frequency to about 10k Hz (as marked with green line)?


texts: general electrical question (with regards to the LBO pin on the Adafruit boost 500 lipo board to a Raspberry Pi)

texts:
So I was getting ready to follow this suggestion Do bi-directional level converters connect either input directly to ground?

In order to pull the LBO pin to my GPIO on my RPi to shut down my Pi if my LIPO gets too low. This is the board I'm using.

https://learn.adafruit.com/adafruit-powerboost-500-plus-charger

According to the first link the addition of the resistor from the 3.3v  voltage of the pi should show the pi 3.3v. but for the life of me it seems that the Out in the diagram of the first answer whould be seeing 5v from the In listed on the same diagram.... am i correct and im about to put 5v into the GPIO pin of my pi or does it in fact work.... if so why??? i cant seem to find the answer though i may not be using the right terms when searching.


texts: How to hash map known values to smaller data width?

texts:
Story:
I have an input bus of 17b = 131 072 values. An output bus of 10b = 1024 values.
Among all the 131 072, only 20 000 values are used and known in advance.
I'd like to map all those 20 000 values to 1024 with the best distribution and the same probability of collisions.
From these 20 000 values, I know which input bits change the least and which ones change the most.

From Karnaugh, I can get an equation to detect if the input is part of these 20 000 values.
Knowing the probability of some bits, I can create custom hash with XOR on the least used bits.

I feel like it's reinventing the wheel.
Questions:

Is there any known way/algorithm/project?
Is truncating a known hash (hash-256? or other common hashes) still valid and give the same probability?

The hash must use add, sub, mult, logic gates and shifts only. To be synthesized in RTL.
Extra question (perfect hash)
Let's say my output is now 15b (32 768 values), all the 20k input values can fit inside.
I believe that represents a perfect hash. Is there a simple way of defining the function? Known algorithm?
As said, Karnaugh's table can help defining the exact equation but it will greatly depends on the association between input and output values.
Example:
Let's say I have 4 values coded on 5bits: 2,7,12,28.
My output is 2bits (4 values, enough to map the 4 input values)
Mapping:
0:2
1:7
2:12
3:28

and
0:28
1:2
2:7
3:12

results in a different equation.
Do I need to bruteforce to find the minimal hash?


texts:
On this board USB2 signals are routed using smooth lines instead of the usual 45° routing seen on the rest of the board. Does this offer advantages or is this even necessary? A theoretical advantage would be "less reflections", but is this real? Note: I'm not asking about equal length paths, which these aren't.

(One disadvantage I can think of is that not all EDA software let you draw traces this way.)

PS: I saw this on the to-be-announced Arduino Zero board.


texts: Frequency response of an input with a phase (steady state)

texts:
I know that, at steady state, the frequency response can be calculated relatively easily from the transfer function and the frequency of the input.

So if we have a system described by the transfer function \$ G(s) \$ then we have (again, at steady state):
$$
u(t) = u_0 \sin(\omega t) \\
Y(s) = G(s) \cdot U(s) \\
|G(j\omega)|=\frac{y_0}{u_0} \\
\angle G(j\omega) = \phi \\
\implies y(t)=|G(j\omega)|u_0 \sin(\omega t+\phi)\\
$$

I never saw anywhere any comments in the many text books I read about a signal with a phase as an input.

Say I have this \$ u(t) \$ (the excitation) instead of the sine with a zero phase:
$$
u(t)=u_0 \sin(\omega t + \theta)
$$

I wonder what will happen. Does the relationships mentioned above still hold true, or not. How can I calculate \$ \phi \$ and \$ y_0/u_0 \$ while accounting for the input phase \$ \theta \$?

I would have difficulty to believe the presence of \$ \theta \$ would not have any effect on the steady state output...


texts: Do i need to use capacitors with a 5v voltage regulator?

texts:
I am using a solar panel with a regular 12v charge controller but instead of using 12v batteries i am planning to use li-po batteries with a specific charger.
I know that the best way to step down  the voltage would be a buck converter but i already have a L7805 laying around. Do i need to use a capacitor at the output ? I have seen some circuits that used it and some that did not and both worked fine. If i do need one how do i determine which one suits the circuit? I am a newb to electronics. I see that capacitors have both voltage ratings and capacitance ratings. I figure that the voltage should be above the 12 volts the charge controller outputs as otherwise the capacitor would be blow up, right? Is the voltage of it relevant? How do i determine the right capacitance?


texts: Condition for negative Thevenin resistance

texts: Is there any particular condition or relation between the impedances and the dependent sources in a circuit by which the Thevenin resistance turns out to be negative?


texts:
I have alot of ATX powersupplyies, i'm planning to use those for some of my experiments... where the first will be a bench supply.

I will probably only need +3.3v +5v +12v.

From what i read an old powersupply which has more ampeeres on the 5v side needs at least 1A of minimum current.... so i will prolly need 10ohm 10W dummy load... but i will test first if it shuts down.

Anyway the question is about the POWER_GOOD / P.G. cable and the POWER_ON / PS-ON ...

The POWER_GOOD outputs HIGH wehen the powersupply's voltages are stabilized.
To turn the powersupply on i need to attach the POWER_ON to the ground.

Can i do something like the following to turn it on when everything is stable?

simulate this circuit – Schematic created using CircuitLab

Or is the POWER_GOOD only active after i ground the POWER_ON?

Another question that is less important...

There is also the +5v standby voltage. Those 5v are always on even if the power_on is not tied to the ground. Is that stable?? I could attach an attiny or whatever microcontrolller to turn on and off the powersupply, maybe wirelessly..and also a display that shows the various voltages. Most of the powersupplies i have say that the max output of the +5 VSB (standby voltage) is more than one amp.


texts:
"In terms of this picture of mapping addresses from the address space onto the actual memory locations, a 4-KB machine without virtual memory simply has a fixed mapping between the addresses 0 to 4095 and 4096 words of memory. An interesting question is: "What happens if a program branches to an address between 8192 and 12287 ?" On machine that lacks virtual memory the program would cause an error trap that would print a suitably rude message,for example : "Nonexistent memory referenced" and terminate the program."

From the above paragraph this is what i understand , this is a 12 bit addressing system as 2^12 is 4096 and each word forms 1 byte (since 4KB X 1024 = 4096 Bytes = 4096 Words) . But when the author says "What happens if a program branches to an address between 8192 and 12287 ?" I don't understand what does that mean.From where do the addresses 8192 till 12287 come up ?(doesn't the processor have a 12 bit addressing scheme ?) And what does the statement "On machine that lacks virtual memory the program would cause an error trap that would print a suitably rude message" mean ? What has virtual to do with this ?

I guess my interpretation is wrong.Whatever it may be please help me understand this.


texts: Help with coupled inductor using Partsim

texts:
I have created the following circuit in Partsim. When I run the DC Bias analysis, the circuit on the left side of the coupled inductor behaves as expected. However, I do not see any voltage appearing on the right side of the coupled inductor. Shouldn't this inductor induce the same voltage to the right side of the circuit?

I set the coupled inductor to have a "Coefficient of Coupling" of 1, an "Inductor 1 Value" of 1, and an "Inductor 2 Value" of 1.


texts:
Sometimes the power rating of a simple zener diode is not enough for some works, but their precious ability is needed.

What to do?

put two zeners in series? I heard that it will work in theory but in reality the break down voltages of the them will not be equal. so the mixture will not work as desired.

What is the solution?


texts: How to calculate a capacitor's discharge time?

texts:
How do i calculate a capacitor with a specific capacitance loaded with a specific resistance discharge time and reach a specific voltage?

So let's say i have a 22uF capacitor charged with 12 volts and loaded with a 500 ohm load, how many seconds does it take to reach the capacitor's voltage of 6 volts?


texts:
I am replacing a microscope lamp with a motorcycle LED headlight. The light is 20W, 9-85V DC; the driver built in and a complete black box to me. I power it with a 65W power supply (18.5V/3.5A). For as long as I have tested it (short), this seems to work well.

Now the original housing had a potentiometer to adjust the brightness of the lamp. Naively, I soldered that in serie with the headlight. For as long as it lasted it worked functionally well to reduce the light, but of course, within a minute, smoke, smell, and the potmeter even emitted red light (it had to endure 20W).

If I understand it well now, I am to reduce the output power fed to the light. Similar questions here suggest a FET is the way to go. What type of FET should I select here (and why?). I sketch below how I understand it now:

simulate this circuit – Schematic created using CircuitLab

Is this the idea? It doesn't need to be very precise as it is only a light dimmer.


texts:
I want to know, is there any website which offers the comparison of two ICs simultaneously.
I don't want to read the whole data sheets. I just want to find the list of differences between two IC's in the same page.
 For eg: Atmega 8 and Atmega 16.


texts: What is the easiest way to test if my oscilloscope works?

texts: I am currently making oscilloscope from my soundcard, which can measure the voltage of about 5V. What is the easiest way to know whether my scope works or not? I don't have access to low voltage AC sources. Can I use an electric motor/generator to generate some signal?


texts: Estimating current when voltage drops > voltage input

texts:
Let's say I have a circuit with a 5V battery and a 2V LED and a 100 ohm resistor. Ignoring certain properties of an LED, I can estimate the current by doing:

3V / 100 ohms ==> ~30 mA

However, what happens when I have 3 LEDs in the circuit? Using the above approach, I would get a current of zero (or an open circuit or whatever it would be called). But this isn't really the case, as shown in a simulator, where I get ~1 mA:

Does using the voltage-drop approach not work where there may be more drops than the input can support? If so, what would be an example of calculating the below circuit to get something 'close to' 1mA .


texts: Why Altium routes trace to the side of the pad?

texts:
I am curious, are there any reasons why Altium tends to route a trace to the side of a pad, instead of the top? The top looks more logical, since it will not disturb other traces in a SOIC for example.
I am including a picture for reference.

EDIT: I am not using Auto Route. It's the snap of the trace on the pad that bothers me.


texts: How can guitar pickups hot leads be wired in parallel without causing current problems?

texts:
I am looking up wiring diagrams for electric guitar pickups and noticing that the common method for combining two pickup signals is just to have a switch that can optionally have both the hot leads shorted together and routed to the volume potentiometer which then goes to the output

The pickups use a magnet and a vibrating metal string to generate an electrical signal. Sometimes guitars can combine multiple pickups using a switch that changes which pickup(s) get shorted together and routed to the volume potentiometer.

I understand the way to combine them in series, having the ground from one connect to the hot from another, and then the second one is grounded and thus when its hot generates voltage it artificially lifts up the "ground" reference for the first one so the total output that goes to the volume knob is the combined signals. This seems like a way to create a passive mixer signal without the need for an op-amp. Incidentally this is how humbuckers work in normal operation (non-coil-split mode) with their magnets being anti-aligned so it cancels noise.

What i don't understand is when they are in parallel, if each generates a different voltage and they are shorted together how does that not cause massive current problems. If the hot of the first is generating 1 volt and the second generates 2 volts and their hot leads are tied together wouldn't it cause massive current (since low resistance of copper wire) between the hot of the first and the hot of the second?

Someone please explain how shorting these together mixes the signals.


texts: How can I model and simulate a resonant inductive square spiral coil in MATLAB?

texts: I was wondering if it was possible to model and simulate my WPT system in MATLAB to determine if my analytical calculations are correct. I want to model my system in MATLAB as I have seen on MathWorks you can do this for a circular spiral coil. Any help will be greatly appreciated thanks.


texts: Relationship between Vds and Vgs- MOSFET

texts:
I've been experimenting around with a MOSFET and was measuring the \$V_{gs}\$ and \$V_{ds}\$ for a range of 0-5V. This is the plot I came up with:

Circuit schematic:

Now I'm trying to discern a relationship here but can't figure out what the constant value from 0-3.2V indicates. I've found 3.2 V to be the threshold voltage. Beyond the threshold voltage I see that Vds falls dramatically as Vgs increases until it levels off at about 3.8 V. Now I'm not very familiar with MOSFET's which is why I'm simply trying to get a qualitative view of this \$V_{ds}\$ and \$V_{gs}\$ plot. What happens before the threshold voltage? What happens after it?


texts: what is the default internal clock for pic16f1946?

texts:
While going through the data sheet, section 5.3.1 says: "Default system oscillator determined by FOSC bits in Configuration Word 1". How can find the value of this default clock, is it 8MHz or 31khz?

I am trying to generate a 10 msec delay and i am using 31khz in my calculations, but i think it is not right.

TMR0_Load_val * 4/Fosc = delay
TMR0_Load_val = 10msec * Fosc / 4
= 78.

Thank  you.


texts:
I have read that using a higher voltage motor would need less current to get the same power. I understand that P = IV and how that works. My question is if the 24 V motor would get half of the current, wouldn't it have half of the torque as well since they are directly proportional? In that case I don't understand how the 24 V would be advantageous at all.

Typically when people talk about motors a higher wattage motor is "better". I don't understand physically how more watts makes the motor "better". It just means it uses more energy per second which I guess would mean it is all converted into mechanical energy but not torque? I don't understand the relationship there.


texts: Can I use 12 V 7 Ah battery with 700 VA inverter?

texts:
I already have a 12 V 7 Ah battery. Now I am planning to buy an inverter which is 700 VA. Can I use that battery with this inverter? Will it be safe?

Regarding load, I will only use 2 CFL/LED/Tube lights.


texts: How can I reduce the PWM noise of a blower motor?

texts:
I've built a ventilation box which utilizes a blower motor from an old Subaru Impreza 1996, which I was gifted from a friendly mechanic.

The flow volume is amazing, but it's a bit too noisy and too powerful.
The motor draws about 20A peak on start, and then operates at 7A at 12V.

But when using PWM, the motor basically sounds like a screaming alien, no matter if the duty cycle is 90% or 10%. I'm using Arduino to send a pwm signal and an IRF3205 MOSFET.

I've tried a low frequency (using delay and delayMicroseconds, 10-1000 Hz), and high frequency (using 32bit and 8bit prescaler of Atmega328). It only changed the pitch of the sound, but it was still very audible. The least noisy was at the low frequency, but then the motor was unstable.

Should I use a capacitor or an inductor? (or both). I haven't worked with inductors before. And I imagine the capacitor won't do much good...

Video: https://youtu.be/kHZ0b0wFjaw

simulate this circuit – Schematic created using CircuitLab

Source code:

digitalWrite(pin11, LOW);
delayMicroseconds(50);
digitalWrite(pin11, HIGH);
delayMicroseconds(100);


texts: How do phone chargers have variable input voltage with constant output voltage?

texts:
My basic understanding is that a transformer can step down a voltage by the ratio of the primary and secondary windings, since this is a ratio the output is not constant.

Thus my question is, how are chargers like the apple phone charger (a Fly-back Switch mode power supply) able to take an input of 100v-240v ~ 50/60 Hz to create a constant 5v output?

Above is a supposed circuit diagram of the apple phone charger.

is this constant output voltage an effect of the flyback transformer? (i have little experience in AC to DC power supplies) Any help is appreciated.


texts: What causes periodic noise with LM386 amplifier

texts:
I am trying to use a LM386 to amplify an audio signal so that I can listen to it using a speaker. I am using the recommended circuit from the data sheet:

When I connect my audio source to the input, I am able to hear the sound in the speaker, but there is a low-frequency noise in the background. If I connect the input to the ground, that noise persists, which indicates that the noise does not come from the input.

Also, the circuit is powered by a 9V battery, which eliminates the power supply as a suspect.

Using an oscilloscope, I connected the (grounded) input to channel 1 and the output to channel 2. As can be seen in the picture below, there is a periodic spike with a frequency of about 15 Hz.

What could be causing this periodic signal?

I admit that it is likely that I made a mistake in my connections, but this is a rather simple circuit, and I already triple-checked every connection.


texts: relation between transmission line & circuit impedance

texts:
What is the relation between the impedance of lumped components and the characteristic impedance of transmission lines?

I have noticed that in some cases transmission lines are loaded with lumped components (e.g. for matching) and in some other cases they are loaded with other transmission lines (characteristic impedances).

I don't understand how the two impedances can be interchangeble, when for example, in circuit theory two series impedances are summed up, while in transmission lines only the reflection coefficent is considered.


texts: Equal voltage sources(different current capacities) opposing in series?

texts:
Given the following circuit:

simulate this circuit – Schematic created using CircuitLab

Assume V1 is capable of applying 10A to the circuit.

While as V2 is capable of applying 100A to the circuit

Would the total voltage in the circuit still be(0) due to them being in series and opposing one another?

Would it matter if "opposing" equal voltage source(like V1&V2) had different current capacities? At the end, they would ultimately cancel out?  Vs. Having them in series and opposing like so:

simulate this circuit

I know the second diagram is kind of odd, but it just shows the current capacities(i.e current sources) being different. With respect to equal voltages.


texts: How to charge lithium ion batteries - BMS (and) TP4056

texts:
I have this BMS module for 3 cell lithium ion battery protection. as this guy explain the BMS modules can charge the batteries but not ideally, so we need a separate charger module to fully charge the batteries.

TP4056 is what i'm gonna use as a charger module.

TP4056 is a one cell module and provides 4.2V output, while each cell connected to different parts of BMS module which requires different voltages from batteries in order to monitor over-charge/discharge.

Does TP4056 module conflict with the BMS?


texts: Big discrepancy between theoretical and actual power through my pulse generator

texts:
I am trying to acquire some skills about pulse generation, but that's not easy.
I've tried to derive the power dissipated by the input resistor in my pulse generator, but it turns out to be much lesser than the actual power (if I am correct).
Where is my mistake ?

The pulse generator is a simple relaxation avalanche transistor pulse generator.

Here is a picture

Edit: the 50Ohm resistors visible in the picture are disconnected. Only the 50 Ohm of the atenuator plays a role here.
Here is my derivation of the dissipated power:

The oscillator is powered via a resistor \$R\$ (\$= R1+R2\$ in the schematic) charging a capacitor \$C\$ (\$C_1\$ in the schematic) and discharging via the transistor into the load resistance \$R_L\$ (=R4 in the schematic).

We can visualize the pulse with the oscilloscope.

We shall assume here that the pulse has roughly the shape
of a right angle triangle, whose right angle corner is at \$(0,0)\$.
Let \$V\$ be the height of the triangle (in Volts), and \$\sigma\$ its basis (in seconds).
So, the equation of the pulse shape is roughly
$$u(t) = V  - {V\over \sigma}t.$$

This gives the energy dissipated in \$R_L\$ by a single pulse:
$$
E = {1\over R_L}\int_0^\sigma u^2(t) dt = {1\over R_L} \bigg[ -{\sigma\over 3V}\bigg(V - {V\over \sigma} t\bigg)^3\bigg]_0^\sigma = {\sigma\over 3R_L}V^2
$$
(1/3 of the energy dissipated by a square wave, this makes sense).
Let us assume the frequency of the pulses is \$f\$, then the energy dissipated in \$R_L\$ in one second, which is also the mean power, is
$$
P_{mean} = fE = {f\sigma\over 3R_L}V^2.
$$

Now, we are interested in the evaluation of the capacitance \$C\$.
Let \$V_{av}\$ be the smallest input supply voltage such that the avalanche transistor oscillations occur.
The final voltage of the capacitor before its discharge into the transistor is aproximatively \$V_{av}\$, so
its energy is \$E_{cap} = CV_{av}^2/2\$. But
this energy is almost entirely transmitted by the pulse to the transistor and \$R_L\$,
so, neglecting the energy wasted by the transistor (that I've checked to remain cool),  it is equal to the energy  \$E\$ computed above. This leads to:
$$
C = {2\sigma\over 3R_L}{V^2\over V_{av}^2}.
$$

Finally, let us evaluate the power dissipated by the resistor \$R\$.
Recall that the energy wasted in a resistor charging a capacitance \$C\$ up to the supply voltage \$U\$ is \$CU^2/2\$ (the same as
the energy stored in the capacitor).
To a good approximation (since \$1/f\$ is much larger than \$\sigma\$), all the current flowing through \$R\$ is used to charge \$C\$.

So, with \$U = V_{av}\$, we have finally that the energy dissipated by \$R\$ in one second, or the mean power, is approximately
$$
P^R_{mean} = {1\over 2} f C V_{av}^2 = {f\sigma\over 3R_L}V^2 = P_{mean}.
$$
This is a curious result: the power dissipated by the input resistor is equal to the power dissipated by the load resistor.

If \$U > V_{av}\$, then we have
$$
P_{mean}^{R} = {f\sigma\over 3R_L}{U^2\over V_{av}^2} V^2 = {U^2\over V_{av}^2} P_{mean}.
$$

Application to my generator (see images above):

\$R_L = 50\ \Omega\$,

\$R = 41 +10 = 51\ k\Omega\$,

\$\sigma = 10\ ns\$,

\$\Delta = 40\ \mu s\$,

\$f = 1/\Delta = 25 \ kHz\$,

\$ V = 1.8\sqrt{1000} = 57\ V\$ (1.8V on oscilloscope, with atenuator 30db),

\$ V_{av} = 150\ V\$,

\$U = 160V\$

This gives
$$
P_{mean} = 5.4\ mW;
$$
$$
C = 19\ pF,
$$
$$
P_{mean}^{R} = 5.8 \ mW;
$$

But I've also measured
\$ I_{supply} = 0.6\ mA\$,

which gives
$$
P^R_{mean \ actual} = R I^2_{supply} \approx 18\ mW.
$$

This much more than the theoretical power.
Where is the mistake/erroneous assumption ?


texts:
I have a good understanding A-GPS functionality. I understand that assisted GPS is used to improve TTFF, works better indoors but costs more as you are using the mobile networks to determine the position.

Let's say you have a simple PCB with a GSM module and a GPS module. Both modules use an antenna.

Is it possible to fully do without the GPS module and the antenna and purely rely on the GSM module to determine the position using assisted GPS? By any chance is this what smartphones do? I understand that GSM antennas come in many different shapes and sizes, but are less affected by physical mass between the antenna and the mast. However, the GPS antenna needs a clear view of the sky in order to determine the position.

If my device is going to be used indoors mostly, would I not be better off completely scrapping GPS and just using the assisted GPS functionality of the GSM module?


texts: Is there a published standard for 'euro modules'?

texts:
Variously called 'Euro modules', 'Euromods', 'Euro modular', these are 'standard' sized units (1U, 2U, ..) that slot into face plates - e.g. a 1-gang face plate can take 2U; 2-gang fits 4U - that can then essentially have any data, power, switch, whatever, on the modular unit instead of having a custom faceplate for every imaginable combination (except the one you want of course!).

(Image from http://www.retrotouch.co.uk)
Is this just a de facto industry standard, manufacturers want to make modules to sell you even if a competitor made your faceplate, or is there an actual BS/IEC/something standard for them?
I haven't had any luck finding one. They're not even on Wikipedia (not to be confused with 'eurorack' or its 'euro modules' which seems to be much bigger and to do with musical synthesisers) that I can find - perhaps there's another/standard name for them that I don't know?


texts:
Given sinusoidal signal at the input, Find the transfer function for this circuit? Assume that the diodes are ideal.

0 is less than V_input<5.5 D1 is in forward region and D2 is OFF(b/c V_input-(-V_input)<11, the potential difference between anode and cathode of D2) Hence V_input=V_Output

V_input>5.5 D1 is in forward region and D2 is conducts in Zener region(b/c V_input-(-V_input)>11, the potential difference between anode and cathode of D2), V_output=??

The same happens for the lower half of input with the states of diodes reversing.

Question:

1)I think I have analyzed this circuit incorrectly, where did I go wrong?
2)What is the transfer function for this circuit?
3) is there a systematic procedure to find transfer function of such circuits?


texts:
This is for an RPM limiting device when the clutch pedal is at the floor. The device is active only when it has either a ground or 12V input active (clutch at floor situation). I would like a circuit that would allow this input to be allowed after an "arm" button has been pressed.

                __________________
Clutch down ___|                  |____________
                   ___
Arm button  ______|   |________________________
                   _______________
Output      ______|               |____________
                                     __________
Clutch up   ________________________|
                                     ___________
Reset       ________________________|

Figure 1. Timing diagram added by @Transistor for OP to edit.


texts:
n my application I've to generate HVDC(~700V) for firing of ultrasonic probes to generate RF signal. Here is the circuit diagram i'm using:

I'm generating two differential square wave(complemented) which will drive N channel MOSFET (RSS100N03) +5V is generated from battery through (LM1117-5 regulator )

EDITS:
Further Details:

Square wave is of frequency ~40-50kHz

U22 is NAND gate SN74LV00

can someone tell me how HVDC is getting generate  here, since as far as I know Transformer works on AC only?
What does RSS1000N03 do here?
Is there any other concept/circuit to generate HVDC from low DC?


texts: Could you program a microcontroller without a computer?

texts:
Let's say you had a rather simple and small microcontroller and had no interfacing, no computer, no debugger, compiler, or assembler. Could you write your code in assembly, convert it (manually) to machine code, and then apply power to the appropriate pins using a voltage source?

I understand you would need appropriate I/O and memory to really do anything, but if you were so inclined and had the time, could you do this? I guess, historically, how was this done when there was no computer/compiler/assembler to begin with? Feel free to link me to an outside resource. Thanks! :)


texts: AC voltage measurement with a microcontroller

texts:
I want to build a circuit that will eventually calculate power, power factor and thd for a light switch or a wall outlet. But I'm having some problems with the voltage measurement circuit.

simulate this circuit – Schematic created using CircuitLab

The effective voltage is 230 +-10V.

Do I need to use a transformer? As far as I understand the only
advantage I'm gaining from it is that it will protect me if I touch
the circuit before R1 (the circuit won't be accessible anyway).
What is the correct equation for C1?
Is there something I am missing?


texts:
This is a diagram for a flashing relay. Normally used for automotive, I'm curious if I can get it to work with my needs.

I want to be able to start and continue the flasher with a 12V output, and while that output is on, flash a light bulb with a separate 12V supply.

Is that possible with this style relay?


texts: What is the difference between a precision timer and LinCMOS timer?

texts:
I'm busy with a certain project that needs a 555 timer chip. But there are different kind of timer chips and I don't know what the differences are.
What are the differences between a precision timer and LinCMOS timer?
I see that the U_CC voltage range is different, but what does this mean for the generated pulses.


texts: Why I am seeing a spike of 9V on output and capacitor in 555 timer

texts:
I would like to have high voltage at output initially for a period of time, then low and high ... . But in the following circuit, I see spikes on output (green) and capacitor (blue) for a short period of time.

Can anyone explain?


texts: What is the ramp rate of a battery used on the grid?

texts:
For grid applications, I am looking for typical ramp rate of Li-ion batteries.  I am specifically interested in batteries used for frequency management.  So suppose I have a 1MW grid connected battery and the grid sees a disturbance in which there is loss of generation.  What kinds of maximum ramp rate can I expect from Li-ion battery in say one second?  Is it 30% of rated capacity per second?

Are there metrics like 0 to 99% rated capacity in N seconds?  What are typical values of N for Li-ion?


texts: Steady State Error of controlled loop system

texts:
I am trying to calculate the steady state error of the following system but unable to do it. I have used MATLAB and calculated the steady state error to be 0.1128 but don't understand the steps that I need to do to calculate this.

Please help.

Thanks


texts: What limit the current of a Solar Panel system?

texts:
I've a two solar panels (CS6C-150P). And each produces:

8,3A (Imp)
18,1V (Vmp)
150W (Pmax)

Charge Controller: EP Solar - LandStar B - LS3024B

They are parallel connected, then produces a total current of 16,6A.

Let's assume that is midday with no clouds on the sky and my batteries have 75% of charge.

In these conditions I saw the panel producing only 11A, why?


texts:
I am trying to get the position and uncertainty of my LIDAR sensor inside a box. For position: x, y values in mm and angle in degree, for uncertainty: σx, σy values in mm and σθ in degree. I am using RaspberryPi with RPLIDAR A2 and programming with C++. I want to get the position of the LIDAR inside the parent box.

Update 1: I am getting data (distance and angle) from the LIDAR and plotting in Matlab. But I need to find the position of the LIDAR in the box. I don't need exactly codes, just steps through it can help me.

Update 2: Here's the plot from Matlab (this reading isn't from inside a box though). Currently the sensor is always at the center if I move it. I want to get the position of the sensor as the box is in a fixed position the thing moving is the sensor itself.


texts:
I'm doing this project called "High data rate logger".

The requirements for this project is to sample the 2 analog signals simultaneously.

2x channel 14-bit ADC
Store 60 MSps (mega samples per second), which is roughly 250 MBps sustained write speed
Storage medium must be able to accommodate 500 GB to 1 TB worth of data

Storage medium:

M.2 PCI-Express is the latest interface for SSDs (solid state drive). But I am not sure if I can interface an SSD to FPGA through PCIe 2.0 x4 (PCI express generation 2, with 4 lanes) Interface, because of its complications.

A host that can interface with the above cards:

Since I am not able to find a processor which has parallel LVDS input lines to be interfaced to ADC, I am thinking to proceed with an FPGA.

But at the other end I have to interface a storage medium like SSD,or SD cards, or NAND flash memory or any other possible solution.

There are many solutions for storage medium with required memory as well as speed. But the problem is interface. Some common memory interfaces are: PCI express, SATA III (6Gbps), SD card interface, etc.

Therefore I would request anybody to suggest which interface would be feasible, easier and better to interface using FPGA.

If an appropriate standard interface is selected, I could go ahead with selecting an FPGA and designing a data logger.


texts:
I came across on this design when I was searching on the internet for BJT switches.

The Ic current is considered less than the maximum allowed sink current of mcu's pin. I was thinking the concept is that when the GPIO would be at low level (0 Voltage, Base-Emitter = 3.3V) the transistor would be at its saturation region and the current would flow throught its channel. On contrast, when the GPIO pin is pulled high at 3.3V, due to biased base (Base-Emitter = 0V) the transistor would be forced off at cut-off region and no current would flow anymore.

The question here is: how much safe is this topology for an mcu?
How much better would I implement a similar concept like this?
I was looking for an active low switch.

I add some extra details


texts: Brokaw bandgap reference unexpected real world circuit results

texts:
I have simulated a Brokaw bandgap reference using NPN 2N2222A transistors with a ratio of 4:1, a TL081 opamp and a collector current of about 5 micro-ampere. The simulation  circuit is below with accurate resistor values. When I build this circuit, it does not act as it should. I double-checked my soldering is correct.

The circuit output adjusts between 1.60V and 21.4V as is adjusted between 0 and 4.7kOhm with a zero gain resistance ratio. As soon as there is a non-zero gain the output is 22V.

Can anyone with experience building one of these circuits explain why it does not work as expected? Is this the usual case or am I using wrong components potentially?

Update:

I followed some advice and redesigned the circuit with emitter resistors. The worked out to be quite large. The design simulation is in the image below:

The circuit works in simulation but not as well as a Zener diode with respect to change in both source and temperature.


texts: Can I use more diodes to reduce the voltage off a diode bridge?

texts:
I have a transformer labeled as providing 9Vac, 3.36 A.  It appears to provide 9.4 v ac according to my multimeter.

It runs through a diode bridge (WAB 040 diodes -- already fried the last version), and at the output, I'm getting 11.3 v (which is consistent with 9.4v AC^2 - 2 diodes).

I'd like to bring this down under 9.5 v.  Can I just attach two or three more diodes until the voltage is sufficiently low?

Obviously, each one is going to waste energy, but I'm not particularly concerned.


texts: How to calculate time interval between current and voltage waveforms

texts:
Is it basically, phase angle / angular frequency?

Also for a ac circuit with a single inductor is the phase angle going to be always 90degres, likewise with a circuit with a single capacitor?


texts: Is fast charging a Lithium-Ion battery from 0% to 30% better or worse for the battery health than fast charging at 30% to 70%?

texts:
According to this answer, fast charging is only recommended for the battery from 30% to 70% instead of 0% to 70%, while I thought that the emptier the battery is, the higher of a C rate it can handle.

So, is what he mentions in his answer correct?


texts: 6.2 V zener shows lower voltage (Multisim)

texts:
I have this circuit with a 1N4735A 6.2 V zener diode. I am trying to figure out why am I measuring 5.1 V across it. The circuit is a transformerless power supply with more or less 60 mA of maximum current.
I've read that insufficient current through the diode may be the problem but 56 mA should be enough according to the datasheet. Right now I am using a simulator but some time ago I had the same problem with a 12 V zener in an implemented circuit. I hope I am not making a silly mistake.
Thank you!

EDIT:
There is 11.2 V across C2, Zener's current is 55 mA and LED's current is 3.5 mA. I don't think the load is draining too much current. The original design uses a C1 = 470 nF. I made it bigger but the result is pretty much the same, lower voltage across the zener diode than expected


texts: Gradually increase DC voltage boost over time

texts:
I am trying to modify or create a circuit that would control boosting of voltage over time so that it would start at the regular voltage, not boosted, and end up at maximum boost, or some predefined value.

I currently have a boost converter that is controlled by a potentiometer, which is the usual design seen online, however, I'd like to get a digital control of the boost over time, to make the gain smooth and over long periods of time.

Initial thought was, of course, to use a digital potentiometer, because that's the natural digital replacement for potentiometer, as the name tells.

However after a couple of searches regarding digital potentiometers, it seems that they're used for much lower voltages, and I am trying to boost from 24v to about 32v, which is way out of range for most digital potentiometers.

However there is available also those rated for higher voltage, but the amp limitation is still pretty low, I myself don't fully understand the working principle of a boost converter, so am not sure whether the current draw from the output of the boost converter relates to the current going through the digital potentiometer.

The main problem to solve is to get a gradual increase from 24v to 32v controller digitally, by Arduino for example, and the question is whether or not the digital potentiometer is a viable solution, what is if there is a better solution for the given problem? and is the current limitation of the digital potentiometer related to the current passing through the boost converter?


texts: Cable tray width selection as per NEC 392

texts: I would like to ask if anyone know what is the meaning of the letter b used in the formula in the table 392.22 National electrical code 2017 article 392, pic (attached)


texts: Basics of high voltage DC motor driver with IGBT

texts:
I'm trying to drive 140V 4.5kW brushed DC pancake motor. I have to change motor speed and direction. All drive actions must be very smooth and sensitive.
I drew a simple 4 quadrant IGBT controlled driver schematic but I don't have enough experience with motor drivers and I need some advice for best way to drive this motor.

At the enterence, I will rectify AC voltage that comes from secondary side of transformer (not shown in schematic.  The primary side of the transformer is 3 phase 440VAC.
What is the proper AC voltage and phase number for this circuit?
My plan A is getting 1-phase 115VAC from secondary side and rectify it to ~160V DC. Is that proper?
I'm planning to use ~600V 30A IGBTs. Is that adequate?
I'm planning to get current value by Hall effect current sensor (ACS758) and motor speed from an absolute encoder. I will use STM32F7 mcu for closed loop calculations and generating PWM signals.
Is there any trick point? Is that the proper way?
I didn't use an inductor before motor.
Is it neccessary for any regulations?
I need expert advice about this driving DC motor issue.


texts: MAX6966 a suitable sink driver for nixie tubes?

texts:
I recieved some IN-14 nixie tubes for Christmas, and was hoping to implement them in a project i have been considering for some time. The details are unimportant, except that each nixie tube should have its own discrete pcb and driver.
After looking at ICs for some time I found the MAXIM 6966, a LED sink driver with some nifty features (though i would have preferred an I2C interface instead of SPI). It seems perfect for my project (driving a single nixie tube) for the following reasons:

Tiny 3x3mm QFN package
Exactly 10 outputs
Open-drain functionality (output pins either low or Hi-z)
PWM functionality on outputs

My problem is this... the datasheet says the outputs have up to 7V protection, but i'm not sure if that applies to both Hi-Z and Low output configurations, or just the Low output configuration. With an output set to Hi-Z, the corresponding pin is likely to be biased to a high voltage such as 170V... well above the 7V protection. So that is to say, if the 7V max condition also applies to the Hi-Z pin configuration then I cannot use it.

I hope it will work fine, but I suspect it isn't suitable. Could someone confirm my suspicion before I dismiss this otherwise fantastic IC?

Here is a link to the product page:
https://www.maximintegrated.com/en/products/interface/controllers-expanders/MAX6966.html

Thanks :)


texts: Is it possible to change Roving rn-171 WiFly module device configuration through SPI and not UART?

texts:
I am interfacing rn-171 WiFly module with PIC18F27J13 chip.
I want to save both USARTs available on the PIC for other purposes.

I am wondering whether I can just connect the Roving SPI pins to the PIC uc,
to bring or activate WiFly command mode by sending $$$ to WiFly over SPI without any need to connect UART pins.

If so, what could be a reasonable simple schematic for the pins connection.
Thanks


texts: How can I raise a CMOS 1.8V output to 5V LVTTL input with a MOSFET?

texts:
simulate this circuit – Schematic created using CircuitLab

I'm trying to drive a 5V LVTTL UART input on a ATMega32u4 with a 1.8V CMOS ouput on a Telit UL865.  I'm using the NTE2987 enhancement mode MOSFET to do the conversion.  When I fully connect the circuit, the output signal doesn't change and the Telit resets every 15 seconds.  When I disconnect RX from the ATMega, I can see changes in the 5V signal, but there aren't ideal for logic levels.  See the pic from my scope.  Is this not the way to handle these translations?


texts:
I am interfacing DS1307 with PIC32MX795F512L using peripheral library. I am able to send data but not able to receive it.

Code:

#include <plib.h>

#define BAUDRATE    115200
#define Fsck        100000
#define BRG         ((FPB/2/Fsck)-2)

#define FCY     66000000L
#define FPB     (FCY/2)

#pragma config POSCMOD=HS, FNOSC=PRIPLL
#pragma config FPLLIDIV=DIV_3, FPLLMUL=MUL_18, FPLLODIV=DIV_1
#pragma config FPBDIV=DIV_2, FWDTEN=OFF
#pragma config FSOSCEN = OFF
#pragma config ICESEL = ICS_PGx2

int main(int argc, char** argv)
{

 OpenUART1( UART_EN | UART_NO_PAR_8BIT | UART_1STOPBIT  , UART_RX_ENABLE | UART_TX_ENABLE, (FPB/16/BAUDRATE)-1 );
putsUART1("START\n");
int res;

OpenI2C2(I2C_EN, 163); // I2C channel Configuration

StartI2C2();

IdleI2C2();
MasterWriteI2C2(0xD0);
Nop();
MasterWriteI2C2(0x01);
Nop();
MasterWriteI2C2(0b00010011);
Nop();
StopI2C2();

IdleI2C2();
StartI2C2();
IdleI2C2();
MasterWriteI2C2(0xD0);

Nop();
MasterWriteI2C2(0x01);
Nop();
StopI2C2();

RestartI2C2();
IdleI2C2();
MasterWriteI2C2(0xD1);
Nop();
MasterWriteI2C2(0x01);
IdleI2C2();
res = MasterReadI2C2();
Nop();
NotAckI2C2();
Nop();
StopI2C2();

 //converting to ASCII
unsigned char x,y,p1,p2;
x = res & 0x0F;
p1 = x | 0x30;
y = res & 0xF0;
y = y >> 4;
p2 = y | 0x30;

char value1[5] ;
char value2[5] ;
sprintf(value1,"%d",p1);
sprintf(value2,"%d",p2);
putsUART1(value1);
putsUART1(value2);
putsUART1("\n");

while(1)
{

}

return (EXIT_SUCCESS);
}

UART is working fine and there is no collision because the function MasterWriteI2C2() returns -1 if there is collision and returns 0 if there is no collision and data transmission is successful & I have received 0, that means data is being transmitted but I don't know why its not able to read back data. Please help.

EDIT:

I resolved the problem which I was facing and now I2C is working as I can see the received value in I2CRCV register is same which I am sending. But I need to send the value to UART for which I think I need to convert them to ASCII but after converting the values will change. Lets say I have set 13 value in seconds register then its value will change during conversion, then how can I set RTC value. I need to make a logic so that I can set the RTC value from UART.
Please help.!


texts: Web-based "snap-circuits" platform and course

texts: Looking for a web-based version of "Snap Circuits SC-300" with related courses/projects, and possibly even has some sort of skill/knowledge based leveling and reporting in between the courses/projects/topics.


texts:
If I have an 8-bit high-speed interface say at 1GHz talking to memory and I want to do interface testing, I can send patterns like AA/55/00/FF.
When I send a pattern like 55 i.e 01010101, every even bit sees a rise transition.
In the case of AA - 10101010, every odd bit sees a rise transition.
In short, I can exercise maximum toggle per bit to see rise/fall delay effects per bit using a pattern like A5 or 5A.
From an electrical perspective does the use of FF and 00 patterns give any additional benefit?


texts: The idea behind using a pull-up resistor

texts:
I want to understand the idea behind using a pull-up resistor.
While looking on the Internet, I came across the following description:

By using these two pull-up resistors, one for each input, when switch “A” or “B” is open (OFF), the input is effectively connected to the +5V supply rail via the pull-up resistor. The result is that as there is very little input current into the input of the logic gate, very little voltage is dropped across the pull-up resistor so nearly all the +5V supply voltage is applied to the input pin creating a HIGH, logic “1” condition.

Source: Electronics Tutorials - Pull-up Resistor Application
I assume the same logic is applied to all pull-up resistor applications.

Why is there very little input current into the input of a logic gate?
What guarantees that?
How do I make sure there is only a small voltage drop on the resistor?


texts: Trying to Fix my remote for my house Fan, is this component a fuse?

texts:
Decided I would try and fix the remote for this 3 speed fan I have a home since it is summer now. Here's the circuitry I'm dealing with here:

So here our are some notes:

There was some battery leakage when I opened it up, but I cleaned the battery contacts. Would this be harmful to say the ceramic resonator or capacitors?
I replaced the IR bulb with no luck (in the right orientation)
All contacts look good, nothing looks like it burned up

My next move was to replace what I think is a fuse below that NPN transitor. Can anyone confirm that little red thing is indeed a fuse? If so, I have a bunch of these standard green ones lying around that I could put in.

EDIT::  Here's the bottom:


texts: Is an EM vector sensor antenna for DoA at 900 MHz feasible?

texts:
I'm contemplating antenna array designs for an easy-to-setup beam forming receive SDR system for DoA (direction of arrival) at the ISM band (likely ~900 MHz). I saw the 3d vector antennas used for the AERO & VISTA cubesat project in 2019 for low frequency radio astronomy. It uses two crossed loop/dipoles and an orthogonal monopole to sample all 6 components. After the SDR takes in the signal, I would presumably need calculate the poynting vector to finally determine the direction of arrival for the signal. It needs to be real time as well.
Is this design something I could copy for 900 MHz. Change the dipole/loop and monopole lengths?


texts:
I am trying to test USB 2.0 Signal integrity (Eye Diagram). For doing that, USB IF Forum lets you download the EHCI HSETT Software from their website. However, I am not able to use it due to one persistent problem: No Host Controllers Found

Even though I have tried reinstalling the software, checking that I have the right 64-bit version and loaded the compliance driver manually(which keeps showing that it has errors in the device manager), I still get the same error. Can anyone help with getting this running?


texts: Grounding and AC Applications w/ Microchip ICD 3

texts:
I have been doing some simple stuff with PIC's, using a $12 cable from Sparkfun to program them. Wanting to do more advanced stuff, I bought an ICD 3 and with it came a warning about proper grounds with respect to AC powered applications.

I'm not entirely certain what you need to look out for when using an AC powered 12v supply on your target, be it a simple wall wart or a regulated linear power supply.

Can someone explain this more clearly than the Microchip documentation? The same warning also came with a USB logic analyzer and I would like to better understand this before I blow something up.


texts:
I have circuit to analyze like that

L = 5mH
Vs = 230V (RMS)
Iload = 10A Constant
Vda = 100V

I should calculate commutation(u) and triggering angle but not known both. I tried to find both by calculating avarage DC voltage with the formula is below:
$$ V_{ort} = \frac{A}{T}\left(cos(\alpha) + cos(u) - 2 \right) $$
But couldn't find because there are two undefined variable. I found a formula that is used for bridge rectifier which is designed by diodes and modified it but didn't work.
Which I found

$$ cos(\alpha) - cos(\alpha + u) = \frac{\omega*L_s*I_d}{V_{max}} $$
Which I modified
I tried to combine both formulas but didn't work again.
At last, I sent message teacher to get some trick and he said calculate the commutation losses, add the commutation losses to avarage DC voltage and calculate the triggering angle as there are no commutation. But I guess there is nothing to calculate the commutation losses.
What can I do for this problem ?


texts: Help understanding purpose of this schottky diode and resistors in MAXIM DS2777 typical configuration

texts:
I am looking to design a pack-side gauge/protection IC and so am looking at the MAXIM DS2777 IC (datasheet).

In their datasheet page 10 is the typical application circuit. I lack understanding with parts of the circuit and was hoping for someone to provide an explanation:

What is the purpose of the Schottky Diode on pin PLS?
What is the purposes of the 1k resistor on the PLS, as a resistor for a internal voltage divider?
What is the purpose of the 1k resistor on Vin2 and Vin1? I don't see what they do at all, the input resistance of these pins are 15Mohm so the 1k here won't really achieve anything (negligible impact to current flow and also very low voltage drop)
Whats the purpose of the 150ohm resistor on Vdd? That doesn't seem to be necessary either..

Thanks in advance!


texts:
I'm looking to find out what these parts are on a PLC controller.

Both are SOT-89 packages.

The AE P04 I suspect maybe something to do with a constant current circuit for +24vDC for a 4-20mA loop sensor therefore I think this could be a LDO regulator.

The BE P04 appears to be part of a 0-10vDC output.  Is this likely to be another LDO regulator used for constant current?


texts:
I'm trying to understand why this simple circuit below works the way does: As it gets darker over the photoresistor (RP) the LED gets brighter.

I'm trying to understand it by following the path the electricity takes through it (from - to +).

My theory is that when the room is bright, the electricity flows through the photoresistor and never actually gets to the transistor's emitter (so the LED stays off). When the room is dark, the photoresistor has near infinite resistance and thus the electricity is forced to go through the transistor (so the transistor is activated and the LED goes on).


texts:
I am trying to do boost converter with using mc34063 ic for my project. When I simulate the circuit on LTSpice with 3.7V input. I can get 5V output without any problem. However, when I change the input voltage to 4.2V (which is fully charged 3.7v 18650 lion battery voltage) I get 2.868V why this is happening? What is wrong? Is this a problem or not?
The whole circuit(red dotted area is the net where the probe I placed):

Output when the input voltage is 3.7v:

Output when the input voltage is 4.2v:

and this is the ltspice draft link itself:


texts: Is my circuit to power 38 kHz LED matrix correct?

texts:
I'd like to send 38kHz signals to an LED matrix to pulse 5V IR LEDs. The intention is that a lot of IR will be reflected when a finger is placed on a translucent 3mm acrylic panel above the LEDs. The reflected rays will be read by a TV IR sensor.
I'd like to check if the circuit I've designed for pulsing the LEDs is correct. On the right is a 16-channel mux connected to an ESP32 on the input. The output is fed to 11 power MOSFETs, which in turn are connected to 11 rows of LEDs that the MCU will switch on 1 row at a time.
In particular:

Is the mosfet section of the schematic correct? (what can I read to understand how to design these?)
How do I choose a value for the resistor next to the MOSFETs?
Do I need a capacitor somewhere?


texts: Problem with DC motor, GND and metallic parts (and yes/no PE)

texts:
I built an actuator where noise, presumably, gives me problems.

The hardware is: a 230->24 volt transformer which
feeds an electronic board which drives a DC motor (via 16 kHz PWM) and other small devices (a 7 LED display, a couple of photocells, an encoder and so on). The motor is mounted on a relatively bulky gear and the motor outer body is also electrically connected to the gear.

The entire board and photocells ARE ISOLATED from the rest, i.e. there is no connection between GND and the metallic parts above, and PE (protective ground) does not even enter the board. The dashed lines show the optional connections which would be absent.

The photocell is powered by the board, and seems very sensitive to noise. It works normally when the motor is off but when the motor moves, the photocell stops working. It doesn't matter whether the metallic bodies are connected or not to the mains earth. BUT, if I connect the board GND to the metallic body, the photocell works again. And again, it doesn't matter whether the metallic parts are connected to the mains earth or not.

What I don't understand is: there is only one low voltage circuit involved; when it is floating the photocell fails - but when I connect GND to the metallic gear, the whole apparatus is still floating exactly like before, but this does make the difference. What am I missing?

Please note: when I say that the photocell fails, I don't mean that the board misinterprets its input; I mean that the relay of the photocell stays excited even when it should not. A different model of photocell works well, but I want to clarify this problem because the photocell that I want to use is perfectly fine with everything else (including setups identical to this one: the low voltage circuit is always floating); only this actuator gives problems, and only when the GND (-24Vdc) is disconnected from the metal mass. The only thing I can think of, is that some noise comes in from the power supply, but I don't see a clear reason for that or, better, I don't see why attaching an electrically floating mass of metal to GND should change anything.

I am seeking for information and hints; what should I measure or investigate, perhaps using a scope?


texts: Why are two stages used for an instrumentation amplifier?

texts:
When we have a two-stage instrumentation amplifier, such as the following.

Why do we need the first stage of the two Operational Amplifiers? Couldn't we just input V1 and V2 into the differential amplifier?


texts: Why there is 3 phase mains input for this AC/DC power supply?

texts:
Here is the specs:
http://www.linmot.com/fileadmin/doc/Accessories_Controller/ps_S01-72-1000_e_recent.pdf

This power supply outputs adjustable DC. But why it has 3 line inputs and an earth??


texts:
i wanna make a FM microphone for my guitar but the problem is that the electret mic itself output a lot of background noise even before amplifying its signal.

so obviously i need a preamp circuit but i don't need high gain or high volume. a low noise output with 1 volt peak to peak signal is ideal. but schematics i found online are relatively complicated and i don't know what they exactly do. so i would be greatful if anyone help with low noise preamp...

for the record this is fm transmitter circuit:

and microphone is just those ordinary mobile mics:

EDIT:
at the moment i am just testing the microphone via pc sound card with trs 3.5mm jack.


texts: LED Driver Circuit for controlling solenoid valve?

texts:
I have a project where I am trying to control the position of a solenoid valve. The valve operates at 12V, 0-2A (0 = close, 2A = open). The system is open-loop and needs a fast response circuit.
I plan to control the circuit using an Arduino PWM "Analog" output.
The first thought that came to mind was an LED driver, since their primary purpose is maintaining accurate, constant current. I already have a high power LED driver IC that has either analog 0-2V or PWM dimming.
Is there any reason why this would not work, or is there a better alternative? I guess my main uncertainty is that an LED is a diode, and a solenoid is a giant inductor, so I'm not sure if this demands a different drive methodology.
Thanks :)


texts:
Reference Manual Chapter 20 of this document describes GPU and basically uses 2 sentences about, it is just present, however it mentions that it supports OpenGL ES 2.1 API. The question is, ST provides drivers for their Linux distribution but im not planing to use one of their distros or any linux at all. Same story with NXP processors, it is present but has 0 documentation on it, and they provide driver for their linux distro.
Is there any MPU out there on a market with solid documentation on all of its parts, including GPU. Or is there any way to actually find an information about this GPUs so i can write a driver my self.
Big thanks in advance


texts: Frequency response of a series RC circuit

texts:
The magnitude and phase plot of the circuit are as in the image below. I have trouble understanding the meaning of phase plot.

The transfer function being a complex quantity has both magnitude and phase.  The magnitude plot of the transfer function is simply provides the ratio of output to input. But what does the phase plot mean? Is it the phase of output voltage being plotted?


texts: How to determine correct replacement transformer for flyback converter in commercial product

texts:
I have an MPPT charge controller that has recently started behaving strangely and upon investigation I found a very hot mosfet and a transformer (below) that has clearly seen more heat than it should have.

The manufacturer isn't particularly helpful in providing information about this. I've been able to figure out what's going on, but not why this happened in the first place nor what is required to repair it.

From what I could determine, the particular circuit is a step-up converter that generates 15V from the original 5V. I have no idea what values are used, it is hard to decipher. The final 15V regulator is a 78l15, so I know the voltage on that end is below 35V and the current will be below 0.1A.

The input signal is a 5V 40khz square wave generated by a PIC microcontroller.

I suspect, though I'm not 100% sure yet, that this 15V is used to drive the main mosfet. This particular controller switches in the positive line (as is the proper way to do it), so a higher-than-input voltage is required. I think this is it. That's why it needs to be isolated.

My question: What would be the simplest way to replace either the whole step-up converter with another -- with the proviso that it MUST be isolated -- or to somehow replace that transformer with something off the shelf?

I do not presently have the equipment to measure inductors. I do own an oscilloscope but lack a function generator. This makes it hard to really get into it further, which is why I would also strongly consider another off-the-shelf solution to just replace the whole converter, possibly with something that's even more efficient.