texts: SDC: constraining same source, different frequency clocks

texts:
Let's say I have a master clock ("m_clk"), which is divided by 2 (using enable to a clk-gater), giving generated clock: "d2_clk".
Both clocks go to separate muxes, with different select, giving generated clocks: "m1_clk" & "m2_clk".
Is there a way to constraint "m1_clk" & "m2_clk", so they can be used without metastability/sync concerns? I.e. so that each of them can consume data from the other clk domain, without CDC syncronization?
Thank you
Edit: I think that the tool will take care of this by default, because they are all generated clocks from the same source clk (since I have not false-pathed these clks). But I'm not certain.


texts: Can I increase range of a near field magnetic inductor from 10cm to 100cm by increasing radius of ferrite rod coil by 30 times?

texts:
I am interested in increasing the range of NFMI - near field magnetic inductions, used in hearing aids.

However the limiting factor is a range of 10cm, typically seen in hearing aids with a coil diameter of 1.5mm.

According to the magnetic field strength formula

According to the formula: A desired magnetic field intensity(B), can be achieved at an increased distance(r) of 100cm, with a radius(a) increase of 31.7 times the initial radius

Am I right in assuming this, or will there be practical problems/ unseen effects for such an antenna with large radius to work with magnetic induction of low frequencies such as 10MHz.


texts: how to interface RS-422 to UART on my MCU?

texts:
I'm trying to interface RS-422 data to the UART on my MCU (TM4C1294ncpdt) to send it through its ethernet interface.

Can anyone help me with how to convert the RS-422 differential signal to be read by the UART?

circuit schematic or what components do i need to do this?


texts: What is the role of the transistor and diode in a soft start circuit?

texts: Please can someone explain the purpose of both the transistor and diode in this soft start circuit


texts:
I'm reading "Op Amps for everyone" (http://web.mit.edu/6.101/www/reference/op_amps_everyone.pdf) and I'm currently studying the chapter about the compensation of op.amps. but I'm missing a passage. At page 111 after explaining why a loading capacitance can add another pole which can shift the phase and decrease stability, it is written that if Zo << Zf the closed loop transfer function is easy to calculate because the loading capacitance IS enclosed in the feedbackloop.

I mean, if the output impedance could be considered a "shortcut" then the output capacitance is excluded from the feedback loop. In fact the next page it is written that the closed loop transfer function is the same as the non inverting op amp one. What I'm missing? Thank you.


texts: Would this MOSFET be suitable for use with an Arduino?

texts:
I'm looking for a MOSFET which can be controlled by an Arduino at 5V, and which can switch power on/off to a Raspberry Pi and peripherals (also 5V) that will peak around 3A of current.  It's a battery-powered project, so minimal wasted energy is ideal, and there is no need to rapidly switch the power supply on/off.  A cursory search for logic level MOSFETS on AliExpress turned up IRFB3006PBF. Its low Rds(on) of 2.5 mΩ seemed pretty good, and it seemed to tick all the right boxes, with a max Vgs of 4V.

The max Vgs means it would definitely be all the way on at 5V GS voltage, right?

Would this work, or have I missed something important that would make this unsuitable?


texts:
i would like to connect a water level sensor* to gnd+pin on an mcp23017.

the pin need to be pulled-up with some resistor. the internal pullup of mcp23017 are 100k if i have read correctly the datasheet.

Now, after wiring everything correctly, the reads when the float switch its closed (so goes to gnd) are a little bit 'floating'.

i checked everything, twice, and ground pin with a jumper (reads are super stable).

my only guess it's that this kind of switch have some sort of wetting current, it's that possible?

i haven't find datasheet of this switches, nor of similar, speaking of wetting/minimum current. of course a 100k resistor limit current quite a lot.

Someone can point me in the right direction?
1) it's possible that i am seeing some 'wetting current'?
2) how much should be the min current for this kind of switch?
3) should i add a 4k resistor, disable internal pullup and see how it goes?

*https://img.dxcdn.com/productimages/sku_436952_1.jpg


texts:
So I am fairly new to using KiCad, and I have encountered a problem. I recently learned how to make hierarchical pins for bus assignments with the notation.
NAME[start_index..end_index]

Everything works fine when I use this notation to connect hierarchical sheets. It even goes by position from the start index of the output to the end index, when the names change between the hierarchical sheets. (I looked at the generated netlist to confirm this)

When I bring the bus into its parent sheet and create bus entries and connections, it says the pins are not connected. Do I need to create another sub-sheet to complete, does it not let you use a bus in the parent sheet?

Note: Error was confirmed in ERC to be unconnected pins, and pins are the only ones in their net.


texts:
I want to build a circuit with many repeating pieces of schematic/pcb layout, and I want to reuse both schematic & pcb layout. Altium offers to reuse schematic, or reuse pcb separately - via snippets and circuit sheets.

But is it possible to reuse both? I.e. when I place another instance of subcircuit to schematic, PCB layout is also automagically copied - and it's all automatically updates when I modify subcircuit... Copying & pasting manually does not work - as it will be a nightmare to maintain if I would need to modify cubcircuit (I will have ~200 instances and ~2000 discrete components total).

Could you suggest how to do it? We've found a script DesignReuse which does exactly this - but unfortunately it does not work in Altium 13: https://code.google.com/p/altium-designer-addons/downloads/detail?name=DesignReuse_v3.3.zip&can=2&q=


texts: Is current/resistance a parabola? (For lack of a better word)

texts: So it occurred to me today that is resistance is the load that draws current, but also the thing that limits it, wouldn't a graph of current to resistance increase, but then decrease?


texts: Transformer open circuit output voltage and current limiting resistor at gate of Triac

texts:
Im kinda new to electronics and have some questions before i solder my projekt together. I want to make an Arduino controlled soldering iron and designed the circuit below. The optocoupler i used is a LTV-817 and by iron i mean the heating element at around 3Ω.

My problem is that the transformer features an open circuit voltage of around 50V AC peak to peak and I am not sure how the optocouler IC1 is able to handle this. Do I have to choose a different resister value?
The second Problem is the current limiting resistor at the gate of the triac. How is the value calculated?


texts:
I am aware of three ways to negate an integer using 2's complement representation.

The standard "invert, then add 1" which is taught in most textbooks.

Scan from the least significant bit, copying bits as you go. When you reach the first "1", copy it, then flip the remaining bits.

Subtract the value from \$2^n\$, where \$n\$ is the number of bits.

By my thinking, the first technique requires two passes through the bits, although the inversion can be done in parallel. However, the silicon to do both steps may already be present (an invert instruction and an increment instruction), so this way may require the least amount of additional silicon.
The second way needs only one pass through the bits.
The third way may work if there is already a subtraction unit. However, I think that most processors these days subtract by adding the negative, so this may be impractical to implement.
Which of these techniques is actually used by a microprocessor to negate a value?


texts: Developing a Hardware Test Plan for a Microcontroller - Past Experience

texts:
I am using this Microcontroller using 3.3V for power.

Using GPIO pins to drive some LEDs and send some ports for sending UART, LIN signals.

I'm using a 16MHz crystal.

Can someone tell me what the main parameters are that I should test in Hardware Testing of the microcontroller?

For example, suppose I have an I2C interface between the MCU and a slave. I would check the Vih, Voh levels, rise time, fall time, frequency, and period of the interface. I am asking along similar lines, what are the major test cases that one might overlook while validating the MCU section in testing?

Please help with your past experience working with Microcontrollers which you might have overlooked during testing and had some issues with it.


texts: Why are THP 1/2W resistors bigger than 1/4W while 1206 resistors are all equal?

texts: How come THM (through hole mounting) 1/2 W resistors are bigger than their 1/4 W or 1/8 W counterparts, while SMD 1206 1/2 W and 1/8 W resistors are equally sized?


texts: Preamplifier before latch stage in comparator circuit

texts:
Adding preamplifier based on simple inverter before latch stage can improve performance of comparator by decreasing offset voltage. Can anybody explain me how it works?

Best Regards


texts: Making a wireless lavalier microphone with ESP8266-07

texts:
I'd like to make a lavailer microphone and receiver using two ESP8266-07 Wifi modules.

I'm using a condenser microphone with it's own preamlifier using 5V.

I want to compare my signal with 300kHz triangle wave (class D amp like) to get 300kHz pulses.

Can I feed this signal to the ESP and transmit it, receive it, and decode it through an LC filter and feed to camera (after some regulation?)


texts:
I know that the maximum output current of a GPIO of the ESP8266 is 12 ma

I have seen the next circuit and I have done it, it works perfectly, I have measured the base current and it gives 10 ma

My question is..., as it is possible that without a base resistor the transistor and the output of the 8266 will not be damaged?

Is it possible that the gpio has some type of protection or current limitation?

Thanks


texts: Transistor, operating point problem, best way to start a problem

texts:
I recently started studying electronics and I have been recently studying transistors, and I didn't quite get the spiel to these kinds of problems where you have to find its operating point. I don't know where it's best to start, what equations to write, what not to write, etc.

If someone could help me with this scheme and also some explanations and tips. It will be very appreciated.

simulate this circuit – Schematic created using CircuitLab

\$ U_{BE}=0.6V\$ and \$\beta_0 = 100\$


texts: I'm having trouble understanding why stabilizability is weaker than controllability and whereas the latter implies the former, the converse isn't true. Thanks for your inputs.


texts:
How would I make a 4-bit shift register with D flip flops so that only 1 LED is active at once. So for example if a button was pushed the first LED would light up and the other 3 would be off. If the button was pushed again the second led would light up and the other 3 would be off etc. I want to be able to do this with 4 LEDs.

This is what I've tried but I can't seem to be able to get it to work. Any help is appreciated as I've just started to learn.


texts: Need help selecting a mosfet to vary switching regulator output

texts:
I am looking for a mosfet to dynamically vary the output of a TPS61236 switching regulator: 5V and 5.5V (need only 2 set voltages). A simple solution according to this article would be to add a mosfet and switch in or out a third feedback resistor using a microcontroller:

Can you suggest a suitable mosfet and where to connect a pullup resistor for a default state (was thinking of internal pullup on output pin):

The TPS61236 datasheets mentions a suggested feedback resistor current of approx 100 x the feedback leakage current: 100 x 120nA, 12µA
The feedback pin regulates to 1.25V
uController output pin voltage driving gate is 3V

Ideally I am looking for a P-channel mosfet capable of currents over 200mA as I have a need for one elsewhere in the circuit and would like to use the same part.

I've tried to include all relevant information but may have missed a few things, if so, let me know and I wil update the question. Help is much appreciated!

Regards


texts: Will there be any performance effect if the torroid coating gets scratched?


texts: How to level shift + / - 1V waveform signal to 0 - 5V

texts:
Currently I am trying to build a portable ECG device where by the ECG signal will then be sent to Arduino UNO where the data will be transmitted via Bluetooth and the waveform will be displayed on Android Phone. I've already built a circuit and have a good waveform. I also managed to successfully transmit the data via Bluetooth and gotten a signal displayed on the phone.
Here is the problem. I just found out (unfortunately) that Arduino UNO only reads from 0 - 5V. However, my signal range from -220mV to + 550mV. That being said, the signal that is being shown on the phone are clipped or only halved are shown and the negative waveform disappears. How do I shift the whole signal so that its value starts from above 0V ? I have tried non-inverting summing amplifier and it does not work, or maybe it was wrong placement to built. I have attached a schematics of my ECG circuit for references. I am supplying my circuit with 1x 9V battery where the power is split into +4.5V/-4.5V. I also have successfully built an analogue 50Hz notch filter. If anyone knows how to solve this, please share. Also, if I were to add summing amplifier, where should I add it ?
Take note, I have 2 signals that I am sending to the UNO. A0 Pin is receiving the filtered signal, and A1 Pin is receiving the unfiltered signal. Both signals need to be level shifted.
I am from a Mechanical background, so don't be too hard on me.

Newly Updated Schematic.


texts:
as general interest I am trying to learn a little about RF, antennas and signal amplification, largely in the context of 2.4 GHz.

I have read about two DIY projects that informed me somewhat:

This Arduino based amplifier, which I understood quite easily, but seems to only amplify signals in one direction, for example, from cell tower to phone, and would require a duplicate unit with antennas reversed to amplify in the opposite direction. Am I correct about that?
This LimeSDR based amplifier, which seems to be more intuitive to me as it has two clear paths, one up and one down, but I'm not sure I fully grasped the need to move the centre frequency ahead of amplification.
I also read this antenna basics document, which helped me understand those topics.

My question is that I feel there's a less complex option: take the example of amplifying wifi. If I set my wifi system to 2.4 GHz channel 7, I know that is around 2442 MHz. If I were to create a pair of dipole antennas for that frequency, and connected them to input and output of an amplifier like this SKY65016, perhaps in the form of their evaluation board, it seems like placing the input antenna in an area of known good signal and the output antenna in a known poor signal area, I would see an RSSI increase in the poor signal area. Is that correct?

I feel like the simplicity of the idea suggests that I am missing something. I think that amplifier chip could only give me a single signal path, but adding a second amplifier with a pair of multiplexors on the antennas would give me the second direction - again, is that correct?

I apologise if there is some big conceptual leap that I have failed to make. Thank you!


texts: TEXTIO : Read past end of file in ModelSim Simulation

texts:
architecture Behavioral of INST_CACHE is

        subtype word is std_logic_vector(63 downto 0);
        type storage_array is array (0 to 2*16 - 1) of word;
        --type storage_array is array (0 to 2**10 - 1) of STD_LOGIC_VECTOR (DATA_WIDTH - 1 downto 0);

        signal InstCacheOut1_t  : STD_LOGIC_VECTOR (DATA_WIDTH - 1 downto 0); -- data output line 1
        signal InstCacheOut2_t  : STD_LOGIC_VECTOR (DATA_WIDTH - 1 downto 0); -- data output line 2

        type load_file_type is file of word;
        file load_file : text open read_mode is "D:\instcachecontent.txt";

        shared variable storage : storage_array;

begin

    clk_part : process (CLK, RST)

        variable index      : natural;
        variable rdline     : line;
        variable char       : STD_LOGIC_VECTOR (7 downto 0);

    begin

        if (RST = '1') then

                -- load ROM contents from load_file
                index := 0;
                readline(load_file, rdline);
                while not endfile(load_file) loop
                    readline(load_file, rdline);
                    hread(rdline, storage(index)(63 downto 32));
                    read(rdline, char);
                    read(rdline, storage(index)(31 downto 0));
                    index := index + 1;
                end loop;

        elsif (clk'event and clk = '1') then

            InstCacheOut1 <= InstCacheOut1_t;
            InstCacheOut2 <= InstCacheOut2_t;

        end if;

    end process;

end Behavioral;

Above is my architecture design.
I'm not supposed to synthesize it, only simulate it in ModelSim.

However, during run, I get this error:

  Fatal: (vsim-3551) TEXTIO : Read past end of file "D:\instcachecontent.txt".

the line the error is reported at is (before the loop)

        readline(load_file, rdline);

This is the content of the file:

00000010
00000010    01111000000000100000000000000001
00000011    01111000000000000001000000000000
00000012    10100000000001000000000000000000
00000013    00001000100001000001000000000000
00000014    11010111111111111111111111111110
00000015    10101000000001000000000000000000
00000016    11111000000000000000000000000000

Any help would be appreciated, since I don't know how can it read past end of file on the first line.


texts: I am a new hobbyist and I have a question which has conflicting answers online. I'm currently learning about rc timing circuits- more specifically- using a resistor/capacitor network to switch on a transistor after a certain time period. Charging and placing the capacitor in parallel with the base of the transistor is clear, but I am having trouble understanding the branch current calculations. When the switch is closed, I know caps act as a short immediately until charge and voltage build. What I don't understand is why I am taught by some that current takes every path available based on ohms law, while a reputable lecturer says that the initial 'short' from a capacitor will take ALL current (even with a branch in parallel) until voltage builds. Can anyone help clear up how current behaves in this situation? Thank you.


texts: Duplicate a FTDI FT232R usb->serial cable

texts:
I communicate with a serial device using a FTDI FT232R usb -> serial cable created by the manufacturer of the device. Everything is ok I can communicate with the device.

Now I have another cable, also using the FT232R chip.

Both cable use the same:

FT232R chip
Serial connector
Driver

And I've also duplicate the information contained in the EEPROM, so the custom cable use the same information (just in case). And I open the serial communication at the same baudrate.

But unfortunately if I write a serial command (using the custom cable) I got no answer from the device.

What can still be different between the manufacturer cable and my custom cable ?
Is it possible to create a perfect copy of a specific cable ?

EDIT:

The first comment suggest that some PIN could be swapped and it will indeed explain why I got no answer from the device.

But the compagny FTDI propose a small software (FT_PROG) that can be use to reprogram the EEPROM (picture below):

There is an option where the pins can be configured.

Does that mean that I could swap the pin programmatically ? (I've not a lot of hardware knowledge) Or the only solution is to swap the pin with soldering ?


texts: I recently got a mini LCD module from Mouser (Newhaven Display Model #NHD-C160100DiZ-FSW-FBW, datasheet here. It came with a 14-pin ribbon-like connector that I've never seen before. Can anyone help me to identify the type of connector, so that I can purchase the female equivalent? See photo below:


texts: I created a textbook supplement for Electric Circuits. Am I missing anything critical?

texts:
Please note I have tried my best to follow the rules of posting and this post follows them as far as I know, thank you.

**Edit: ** The course covers the following sections:

Circuit Variables
Circuit Elements
Simple Resistive Circuits
Techniques of Circuit Analysis
The Operational Amplifier
Inductance, Capacitance, and Mutual Inductance
Response of First-Order RL and RC Circuits
Natural and Step Responses of RLC Circuits
Sinusoidal Steady-State Analysis

Hi, I am a second year Engineering student, and I designed a textbook supplement of sorts in preparation for my Electric Circuits course.

A rough draft can be viewed here.

The purpose of this is to help myself and my classmates with the course by only having important equations and definitions, and not derivations and other non-directly useful elements.

My question is, does it appear as if I am missing anything critical that is not included? Additionally, is there any mistakes that I made? As I have not myself began the course yet, all my knowledge is purely based off of several textbooks themselves, so errors may have been made unbeknownist to me.

I realize this is unconventional and cannot replace a traditional textbook; I mainly began this project as a way to learn more LaTeX and become familiar with the course.

Thank you very, very much.


texts: How do I find R without knowing anything about it?

texts:
Given this circuit, how do I find \$R_1\$ and the gain of the gain G of the voltage-controlled current source if \$V_2 = 8\text{ V}\$ and the 20 V voltage source supplies 4 W of power?
I tried using the current divider formula to find \$R_1\$ but ended have having a negative resistance, so I'm pretty sure it's wrong.


texts: How many UART lines should I connect between module and host

texts:
I have an LTE module (quectel bg95) that gets AT commands from a host esp32 (esp32-wroom-32ue) via a UART connection.  And in the ESP documentation AT manual to send AT commands I should connect: RXD, TXD, CTS, RTS.  But in the module's hardware integration manual it shows many more connections shown below.  Which lines do I need to connect to send AT commands?
Edit...  Datasheet info that may help decide which connections are necessary.
The the only other info in the datasheet I could find regarding the main UART connection (for AT commands) is as follows:
The module provides three UART interfaces: the main UART, debug UART and the GNSS UART interfaces. The main UART interface supports 9600, 19200, 38400, 57600, 115200, 230400, 460800 and 921600 bps baud rates, and the default is 115200 bps. It is used for data transmission and AT command communication, and supports RTS and CTS hardware flow control. The default frame format is 8N1 (8 data bits, no parity, 1 stop bit). The debug UART interface supports a fixed baud rate of 115200 bps, and is used for software debugging and log output. The GNSS UART interface supports 115200 bps baud rate by default, and is used for GNSS data
and NMEA sentences output.
So the datasheet specifically mentions functions of RXD, TXD, CTS, RTS but I am not seeing anything for DTR, DCD, or RI.  What are these?  datasheet


texts: SMBus: Is 100 kHz clock a risky frequency?

texts:
I will communicate with a device via SMBus. I use PIC18F26K83 for this. In SMBus spec it says clock minimum clock frequency is 10 kHz and maximum clock frequency is 100 kHz. Would it be a risk to use 100 kHz clock frequency since it is the boundary and max limit? Or is it safer to go with 75 kHz for example?

I will be using multiplexer and communicating with 3 smart batteries. Reading their SOC and send these data with UART to another PIC. Cable length from batteries to PIC will not be more than 1 meter long. I am planning to make MCU clock also 100 kHz.


texts:
I have a question regarding a scenario I found myself in, hoping that someone can clarify if the scenario I'm going to illustrate is possible (short premise: I'm a programmer, I'm not an electrician nor an electronic expert).
In my company we have 5 badge readers daisychained using RS485 and connected to an RS485 to ethernet adaptor which is connected to our LAN.
While working on renewing our server room the RS485 cable got cut by mistake by a tecnician of company A.
The day after, a tecnician from company B (the company that installed the badge readers and the software that collects the data) went to the office and said that the rs485 board on those 5 readers got burnt by a short-circuit caused by the cut cable while the devices were powered on.
Since the readers now have to be changed, they suggested to move on ethernet ones.
Cutting the cable without being sure of it not being useful was certainly a mistake.
However here's my thoughs:
On one side company B may have exagerated the damage just to convince us to buy 5 new badge readers (I cannot know if they are actually burnt and I was not there when the tecnician came).
On the other side I have company A that isn't keen to pay for 5 new badge readers for a damage that they think is impossible to be caused the way it was described.
I too, to be honest, find a short circuit surprising, but again I'm not an expert and In my programmer experience I've seen plenty of very unlikely things happen.
I've also found on the internet different people burning their CIA chip on a C64 because of a cable unplugged while the machine was on, so to my unexperiend mind the short-circuit board-burning story may hold as well.
Of course I don't expect a black and white answer, rather I'd like to know similar experiences or an advice from someone that is experienced on this field.
Thanks in advance.


texts: Why do these LEDs have different brightnesses

texts:
I did a search for 0603 sized high brightness Kingbright LEDs on element14, results are here .

Why is there such a range of luminous intensity, even within the same colour, despite forward voltage, forward current, size and viewing angle being the same?

I am using the LEDs as indicators in a very low power battery powered device. The LEDs will be pulsed at times to give user feedback. Would the LED that gives the brightest output be the one that gives the highest luminous intensity, or is there another consideration?


texts: Quartus II: Where are the worst-case paths?

texts:
In the Quartus II settings (under TimeQuest timing analyser), I have checked the Report worst-case paths during compilation checkbox.

However, I do not see any worst-case paths in the TimeQuest report. How can I generate timing worst-case paths in Quartus II version 12.1? Is there a way to manually generate the worst-case paths report?

The target FPGA is a Stratix V. It seems that when the target FPGA is a Cyclone IV, all works fine, but not for the Stratix V.


texts: Using a boost converter as a laser driver for high power diode

texts:
I want to power this 7W 450nm Laser Diode (Nichia NUBM44) using a 3.7V 3.3Ah Li-ion Battery (ICR18650-3350-F). The power required by the laser diode is 5V@4A. Most laser drivers I could find qualified for this type of diode (For example, the ACS4500BU) required a power supply of 6V.
I could use a boost converter in addition to this driver, however I am in a space-constrained project and feel it would be much more convenient if the boost converter could also act as a driver by giving back a constant current.
I managed to find a boost converter (MAX1709) which could take an input anywhere from 0.7-5V and output either 3.3V/5.5V @ 4A. This seems perfect, as my diode takes 5V@4A, and from what I can tell the datasheets claim it has voltage as well as current regulation.
I've been drawing the connections in KiCad, and am somewhat confused with the MAX1709 datasheet on how and what I am supposed to do with certain pins.
This is where I need help:
I want to know if the connections I have so far are correct, and if not what I would need to do to fix them. I also would like to know that even if I got the connections down perfectly, would this be a relatively safe system for powering a laser diode, or is there something more to a laser driver than just a voltage/current regulator?
With that said, here is my current setup in using the MAX1709 to convert a 3.7V, 3.3Ah battery to a 5V@4A power supply. Fair note, there is more to my setup than just the MAX1709, however I will only mention the connections that concern the MAX1709, as I am most unsure if that is correct (I'll leave a description of each of my connections below.)

PGND: Connect all other PGND pins together, then to GND

LX: Connect 2, 3, and 4 LX pins together, as well as Vin, and finally a set of two parallel 150uF capacitors for current stability and a 5A Schottky diode connected to OUT (the datasheet mentioned using an inductor for 'switching frequency', not sure if this matters however.)

FB: PGND (to internally allow for the setting of voltage.)

GND: Connect all other GND pins together, then to GND.

ONA, ONB: Not Connected (Don't need functionality.)

CLK: Not Connected (Or do I need an oscillation for my diode?)

3.3/5: OUT (pull to high to indicate 5V output.)

SS/LIM: Not Connected (Is this safe?)

REF: Not Connected (Not really sure what it's used for.)

EP: Not Connected (In the future I'll probably connect it to the ground plane or add a heatsink to dissipate the heat.)

OUT: Connected to 3.3/5 pin, a 2ohm resistor for 'stability', and a diode to LX pin, and the anode of the laser diode.

Laser diode: Connect anode to OUT pin, and cathode to GND.

Li-ion battery: Connect GND to GND plane, and +3.7V to a pushbutton to turn the laser on/off, then inductor (?), and finally the LX pins

As I mentioned, this was only a list of the connections concerning the MAX1709, but if you see anything else wrong with my setup feel free to point it out.


texts: What is the current component at the input of dc-dc converters?

texts:
The table below describles state space analysis in the field of power electronics. It is from a paper entitled "Signal Flow Graph in Loop Gain Analysis of
DC–DC PWM CCM Switching Converters by Wing-Hung Ki, Member, IEEE."

As shown in the picture, the input vector u(t) has the current component \$i_2\$. Unfortunately, the paper doesn't explain what it is. Could anyone clarify that?  For dc-dc converters such as buck, boost, buck-boost, the only input component that I know is \$V_g\$. So I have no idea what the input current \$i_2\$ is.


texts:
I need to design a 4-input sequence detector and I'm really having trouble with this.

The numbers are entered as a 4 digit input (0010 is 2, 0110 is 6, etc).

The sequence must detect, for instance, a 5 digit key (i.e 3-4-1-7-5)

I'm really troubled with the design methodology for this problem, because if we do it the traditional way, it's going to take forever, we need 3 state variables and 11 different inputs possibilities to deal with (the 1010 key is "clear")

If we type 3-4-4, the sequence must clear, for example.

If we type 3-4-1-7-5 (the correct sequence), then the output should be a logical 1.

Otherwise, the output is zero.

Any help greatly appreciated.

EDIT: the sequential circuit is synchronous (has an external clock source)


texts:
I've researched much about the delta sigma ADC and understand to some extent its workings. The delta sigma modulation in the ADC allows for increasing the ENOB by increasing the SNR through noise shaping the quantization noise out of the band of interest.

However, for a DAC, the quantization noise is already a part of the incoming digital stream. It seems, to me, that the delta sigma modulation scheme would not provide the DAC with any inherent benefits. Yet most of the literature I've looked at have explained the ADC in depth then mention the same can be done with a DAC.

Am I missing something?


texts: Phone travel charger for powering circuits dangers

texts:
I am thinking of using a phone travel charger to power a circuit.Ratings:
input:110-240VAC(my outlet has 220volts) 50/60Hz 0,3A
output:DC 5,2volts at 400mA
The problem is that 220 V are of course dangerous and I 'm not sure of how safe is my charger.
My question is:do phone travel chargers have fuses inside them in case there might be a component failure and an electric shock would become possible?
I also opened the case a few times ,but I didn't modify anything inside and before I put it back last time,the circuitry was intact.
EDIT:Here are the requested images-


texts:
Good Morning All

I have a DC link Choke ( Common EI Core), When measuring through LCR meter It gives me reading (see table.). When Adding Inductor in Series ( Pic 3 and Pic 4) it Give the value that is not expected. I am referring formula to calculate inductor in series Leq=L1+L2+2Sqrt(L1*L2). Don't Know why LCR meter is showing different.

Value shown on image is measured form LCR meter. Measured on both 100Hz and 1Khz.

Pic1 :- Measure L1 Inductance using LCR
Pic2:- Measure L2 Inductance using LCR
Pic 3:- Measure Leq Inductance using LCR ( L1 and L2 in series and in phase )
Pic 4:- Measure Leq Inductance using LCR ( L1 and L2 in series and in out phase )


texts: Add ground earth to a Chinese music player

texts:
I have this Chinese Portable Rechargeable Mp3 player.

It has a two pin plug connector behind that is used to recharge it and some generic rechargeable non removable battery inside it.

It has the following connecting points on the top:

Speaker out
Line in
Usb
Sd Card

Whenever I play it with the plug connected to wall outlet, it has mains current flowing through the line out and speaker out. When I insert one end of the 3.5mm pin in the speaker out, I get full 220 volts shock in the other 3.5mm male pin end.

I tried doing this with the other line in port too, even that is releasing 220 volt current. This happens only when it is plugged in for charging and used. It does not happen when unplugged and played.

I am uploading few pics.

The red wire is for the antenna

I want to correct this design flaw. I want to add ground to this device. (am I right with my decision?).
where should I solder a third wire on the circuit board for ground?

______________________________________

RM:
IT IS ALMOST CERTAIN THAT THE RADIO IS "DESIGNED" TO BE CHARGED FROM A LOW VOLTAGE AC SUPPLY AND NOT FROM MAINS.

While it is not 100% certain what all the circuitry present is it seems that the diode bridge that converts AC input to DC is connected directly to the battery. Even a low voltage power source would damage most batteries if used this way. Connecting AC mains is liable to damage the device, the user and the battery.

Red is (probably) positive.
Green is (probably ) negative.
Purple is AC.


texts: Gain margin and phase margin in Nyquist plots

texts:
Finding gain and phase margins from Nyquist plots is basically finding the margin of change in gain and phase beyond which the plot encircles -1, respectively, with the assumption that the Nyquist plot should have 0 encirclements of -1 for stability.(Reference
 link)

But what happens if the encirclement does not have to be zero for Closed-Loop Stability (because of Nyquist Criterion)? How can one find Phase and Gain Margin if the encirclements around -1 are not zero for a Nyquist plot?


texts: I recently ordered and CJMCU-200 FT200XD a USB to I2C and I am trying to read information from a BME280 using it's I2C output. I am new to FTDI and am having some trouble finding information on how to setup such a device. I plan to write a program the would read in the serial data. My question is did I get the right kind of USB to I2C chip? I have been reading other questions and the problem half the time is the wrong chip.


texts: Bandwidth analysis for photodiode TIA using matlab

texts:
The schematic below show a photodiode TIA circuit, and i tested by using an led as a light source, and by connecting the PCB to the osscilloscope using the bnc connector to see the response of the circuit to the light, i imported this data in matlab to make some analysis on it.

simulate this circuit – Schematic created using CircuitLab

the figure below shows the output i got, which shows the falling edge and i would like to analyse this data to obtain the rise time(maybe by mirroring the output signal) and fall time also the bandwidth, and until now i have no idea how this can be done using matlab, so if anyone can help me with that, it will be great.

I was able to construct the whole pulse from the data i have and you can see it in the figure
what i would like to get is the bode plot so i can determine the 3dB frequency using matlab, so if anyone can help with that i will appreciate it


texts: I got red square part from a circuit, i searched about it and found out that it's also a capacitor calling "non-poloar" capacitor. it's rating is 600v. I have charged other type of capacitors before. but i'm not sure how to charge this capacitor. I have safety measures, I only could find about the difference between "non-polar" and "polar" capacitors. Can anyone tell me how to charge this thing?


texts: Reducing circuit to resistor and capacitor in parallel

texts:
Given the following circuit, in which the value of C1 is known to be 9.3 pF and in which the cable to the probe contributes an additional capacitance of 45 pF between the oscilloscope input and ground and an AC voltage is being applied at V1:

I want to determine the input impedance as seen by V1, in the form of a single capacitor and resistor in parallel. How would one go about it?

I know that the impedance of a capacitor and resistor in parallel is given by:

$$Z = \frac{1}{1 + i \omega RC}$$

So I can find out the impedance of the C1 capacitor and 9 Mohm resistor, and of the 30pF capacitor and 1Mohm resistor and add them. How do I add, however, the impedance of the 45pF capacitor that is connected to the ground to the circuit? And, after that, how do I express the impedance of the whole circuit as a resistor and capacitor in parallel?


texts:
Im designing a high voltage circuit and I have a trace at a different potential than the capacitor it's running underneath.

My question has two parts, in general, what is the insulation around capacitors in general and is there a rule of thumb?

The second is in my particular case, I have 300VAC difference between my resistors and my trace running under my capacitor. The datasheet for the selected capacitor is here:https://www.mouser.co.uk/datasheet/2/212/KEM_F3033_PHE450-1104182.pdf

How do I find out whether is insulation is good enough?


texts: Power circuit design logic -- suggestion

texts:
I am designing a board where my Microcontroller is powered by LM7805 regulator & my load requires 3.8 voltage, is powered by following voltage regulator NCP57302.

http://www.onsemi.com/PowerSolutions/product.do?id=NCP57302

As per the specs of NCP57302 to produce 3.8V i have selected :--
R1 = 30.96K
R2 = 15K

Is it the right set of resistors values to be used for producing 3.8V ?

Also I need some external circuit to be put on enable PIN of NCP57302.
So that microntroller & control the turning ON/OFF the power supply of load.

Can some suggest this external circuit for controlling the enable pin of NCP57302 regulator by my microcontroller ?

Please suggest.


texts:
Why do most household appliances (flashlights, wireless controllers, keyboards, etc.) use two or multiples of two batteries, side by side? The circuit could surely be complete with just a single battery, or three batteries, or five batteries, or whatever.

Why the even number of batteries?


texts: Why would the output voltage of a 5V SMPS (USB charger) increase with load?

texts:
I've been using a USB voltage/current measurement device to evaluate power consumption of USB devices and performance of USB chargers and batteries. Most of the USB power supplies I've used are switched-mode power supplies which have a no-load voltage just over 5V and sag by varying amounts under load; however, I've noticed that one of my USB chargers, a Samsung "Travel Adapter" (5V, 0.7A rating) supplied with a feature phone, exhibits a significant voltage increase under load, until the supply's limit is reached.

Here's what I'm getting:

Amps    Volts   Error
0.00    5.11    0.02
0.03    5.14    0.02
0.06    5.17    0.02
0.12    5.20    0.02
0.17    5.23    0.02
0.25    5.28    0.02
0.31    5.32    0.02
0.35    5.35    0.02
0.41    5.39    0.02
0.46    5.41    0.02
0.50    5.42    0.02
0.56    5.45    0.02
0.61    5.49    0.02
0.64    5.51    0.02
0.67    5.53    0.02
0.70    5.54    0.02
0.73    5.55    0.02
0.82    5.60    0.02
0.83    5.59    0.02
0.85    5.07    0.05
0.89    3.90    0.15
0.93    3.70    0.25

Notice that the voltage rises as the load increases up to 0.82A. Trying to pull more power than that causes the voltage to fall off a cliff as the limit of the power supply is exceeded.

I find this behavior to be bizarre because no other SMPS I've worked with outputs increased voltage under load. What kind of SMPS design would cause the voltage to increase under load, and how would be it different from more typical designs? What advantages, if any, would this design carry?


texts:
At my workplace we have to monitor devices that operate at 433 and 869 MHz, but lately there's an area that for some reason has a transmitter, that isn't ours, jamming the communications. The signal is operating at 869.525 MHz, completely covers a small town and, has far has we know, doesn't seem modular and emits 24/7.

Is it possible to build some kind of circuit capable of getting the distance, signal strength or relative position to find out the origin of this problem?


texts: Help in choosing correct power supply for LED matrix

texts:
I'm quite new to electricity and electric components. I'm building an LED matrix from scratch on a small PCB. I will be using an IC for multiplexing, Transistor for controlling external power supply besides Arduino, resistors and of course the LEDs.

Now, my general question is - power supply of what type(constant-current vs constant-voltage) and what values(Voltage + Amps) should I buy?

My PCB with already soldered LEDs looks like following:

3 parallels of - 5 3mm blue LEDs in series. Forward Voltage 3.1V; Current: 20mA - each.
3 parallels of - 5 3mm white LEDs in series. Forward Voltage 3.5V; Current: 35mA - each.

Now, after reading tons of articles on Current, Voltage, power sources and so on, there are still questions to which I don't have definite answer. I want to understand the core of all these, so I have following questions:

1) Can I power all 6 parellels, meaning whole PCB with one power supply? If I have understood correctly, I can not. I will need a separate driver for each of the LED color. Correct?

2) How should I calculate the driver values. In my understanding - 5(LEDs in series) x 3(parallels of blue) x 3.1(V each LED) = 46.5V. For Amps, should sum up the values of all 15 LEDs also, or should I calculate by just one LED as the Amps are same across the circuit? To sum-up, I will need a driver of 46.5V / 20mA?

3) Should the same calculation be used for white LEDs, and then two separate power sources connected together somehow?

Please help me to understand not just the values of the power source, but also generally the idea behind the topic. Should I be considering something else into my calculations? Any advice for a better design? Thanks a lot.

simulate this circuit – Schematic created using CircuitLab


texts:
The question is as follows:

The solution is as follows:

I am confused as to how he just simply made the 20° as the reference instead of 0°! and using the maximum value instead of the rms value which is always used!
Source:
PPI PE Power Reference Manual, 4th Edition – Comprehensive Reference Manual for the Closed-Book NCEES PE Exam
Publisher : PPI, A Kaplan Company; Fourth edition (January 31, 2021)
ISBN-10 : 1591267838
ISBN-13 : 978-1591267836
by John A. Camara PE


texts:
Is it a bad practice for any reason to put a via in the middle of a trace? For example, in terms of impedance, or reflection?

I have a power trace which I need to get across a bunch of signal traces by hopping to the other layer, and I'm wondering whether it would be best to put the via in the middle of the trace, like this:

Or if I should attach it using another trace, like this:


texts: How can I isolate an ATTiny from an I2C slave so ICSP will work?

texts:
I'm building a small circuit to blink some LEDs with an ATTiny.  I'm planning to use a 16-channel LED driver and talking to it with an ATTiny over I2C.

I'd like to use a SMD ATTiny and add some test pads for programming the microcontroller.  I'm concerned that the I2C interface with the LED driver may prevent the ICSP from working correctly.

I'm considering putting a diode on the ICSP power pin so that it won't power the LED driver.  I'm thinking that without power, the I2C pins are probably high-z.

I could also use a transistor to turn off the LED driver.

First, would this even work?  Second, should I use a diode or a transistor?  Third, what kind of diode or transistor should I use?

Here's where I'm headed . . .

Basically, I was thinking I could use the 4th test pad and a transistor to switch power off to the rest of the circuit.

Thanks a lot!!


texts: Offsetting Op-Amp output offset in combination with charge pump

texts:
I want to have a +-12.0V square wave output from an opamp fed from a 3.3 and 5V power supply. The signal is 2.5kHz with a low duty cycle of 3-10% generated by an MCU. Peak voltage at both ends need to be within 0.1V from +-12V. The load I am driving is 1kOhm so max 12mA. The slew rate requirement is 20V/us.
I have have tried a 5V to +-12V DC/DC converter as well as chargepump a. Given the low load I would think a chargepump is the most econimical. Using rail to rail opamps gave me 11.9V but I have never found an opamp with high enough slew rate. Meaning the rail to rail opamps seemed to0 slow.
Then I have searched for ‘trimmable’ charge pumps at say +-12.5V that would drive a faster opamp with a 0.5V output drop but have just not found it.
Was just wondering if you guys could help me with this. My situation is just easier with a more accurate 12V output. Even 11.9 has some downsides. Thanks

EDIT:
Built the circuit per first answer. It works great!. Albeit the output is inverted. I solved this by modifying the circuit. Removed the inverting transistor for the +12V and added a second inverting transistor for the -12V side. But other than what I had expected, the circuit became clearly 'slower' in the second, non-inverting case than it was in the inverting case per the first answer.
I learned (by doing) that switching at 3.3V is slow and at 12V it is fast. What I do not understand is why the transistor M22 that I added makes the circuit slower. It is switched at 12V. What can I do to make my signal faster? (note that I simulate at 1Mhz and will build at 2.5kHz).
Top schematic: inverting, bottom: non-inverting:

Response graphs of OUTPUT (inverting schema) and OUTPUT2 (non-inverting schema). Clear that OUTPUT2 is 'slowish'.

Probably better way to switch a -12V signal with at the inverse of a 3.3V signal than what I have done. Help appreciated!!


texts:
I have a main computer that has a RS-485 board. It communicates with its sub systems via this comminication board.
I have also a test computer thas connected to main board via RS-485 channel. It will be used for test and update the sub systems using this RS-485 channels.
I want the main computer behave transparently to test computer so that the main computer wouldn't know about test algoritm. I don't want to update the main computer when the test algorithms change.
If I'd designed my hardware I would use a FPGA to connect test computer to sub systems physically so that the test computer would connect the sub systems directly and the main computer wouldn't know about tests, but I use standart computer and a communication card.

What would you do to connect the test computer and the sub systems without adding test related algorithms to main computer.


texts: Calculating maximum power transfer for given circuit

texts:
Someone sent me this question along with an answer. However I am completely unable to calculate this using either KCL or KVL.

simulate this circuit – Schematic created using CircuitLab
The value for R is 10 ohm for maximum power transfer. But as per my calculation maximum power transfer will be on a value Rinfinity. (With R increasing V1 increases which in turn will increase current 0.1V1)


texts: Parallel 'Gang' Wiring Several Solar Panels

texts:
I need to connect 3 similar 180W solar panels to my MPPT. Each one outputs max 9A. I would like to send a + wire and a - wire for each panel back to either a bus bar or a fuse box... and then use a 4AWG jumper from the bus/box to the MPPT controller. if the fuse box is even necessary.

So to clarify, I want to 'gang' up all of the + and all of the - at one point, either the bus bar or fuse box.

The MPPT can handle input of 50A max.

Is this possible, and do I need fusing at each hot line carrying 9A? It should be well within my MPPT to handle all 3 panels unfused. I'm just worried if I gang up all of the hot lines can a 27A short somehow appear at one panel and ruin it. Please advise.


texts: Solenoid : how dimensions ratio affects the magnetic field?

texts:
For a constant length of copper wire (with constant diameter), how can I calculate the most efficient solenoid diameter/length ratio ?
(i.e. what ratio produces the strongest magnetic field, if the current through solenoid is constant)
Is there a general formula or some table for a rough estimation?
Coil has no core. (Air core)


texts: Regulating a steam-powered model generator

texts:
In this age of questing for ever-more-efficient circuit designs, I have been presented with an anachronistic design problem: I need to keep a roughly constant load on a steam-powered turbine generator. So I am looking for a linear regulator circuit that can dissipate slightly over 50W when all of the system electrical loads are switched off. And this is in a hostile environment: It's attached to a model steam locomotive, so exposed to relatively high ambient temperatures.

I presume such circuits were once commonplace (for example in early automotive applications... or in real steam locomotives!) but I am not finding a lot of reference information on them online. Can anyone recommend a good design resource for such circuits? And perhaps an existing linear regulator part with a scheme for dissipating that much power in a high-temperature environment?

The raw output of the generator is specified to be 3-phase AC, 0-12V (RMS? Peak-to-peak?) and 0-4.2A.


texts: How to setup a simulation on QUCS for a RF differential source?

texts:
I need to setup some simulations on QUCS for the RF circuit below:

Pin1 is IC's positive port and Pin2 is IC's negative port.

My initial goal is to investigate the circuit behavior on different frequencies and different lumped components values. After that, I want to calculate the impedance matching and best pcb transmission line.

I saw many QUCS examples, but all of those is using a single power source.

So, how can I setup a differential signal source on QUCS?

pointing to an example would be very helpful !


texts:
I am using the LM5069MM-2 from Ti for a project. This project requires an over current protection limit. The LM5069 can do this and the data sheet shows how. But I don't understand the process Ti uses to determine the effective sense resistance.

Here is the problem:
The application current limit must be 3.8A. To set this current limit a sense resistor, Rsns, is selected. The selection of Rsns is based on the minimum threshold voltage (48.5mV) the SENSE pin of the LM5069 reads before it initiates the over current protection and the desired current limit:

Rsns = 48.5mV / 3.8A = 12.76mΩ

But sense resistors only come in whole value increments 11mΩ, 12mΩ, 13mΩ...
So what we can do is reduce the effective resistance of the next larger sized resistor i.e 13mΩ to get an effective resistance of 12.76mΩ.

Here is where the confusion begins to take place:

How are they determining the values of R1 and R2? What theory are they using? The way they are doing it does not make sense to me. They just find a ratio of R1/R2 based of the sense resistor value I need verses the one I have. Then they apply a voltage divider-like equation to get an effective resistance. Can someone please shine some light here?

Here is a snippet from the data sheet that describes their process for finding the effective resistance.

Thank you for your time,


texts: Determine voltage regulators for a circuit

texts:
I'm trying to determine if the switching voltage regulators I want to use in my circuit are suitable.
I want to use the regulators to change a 50V line into a 5V line that supports motors.
The motor has a nominal current of 0.7A. Its stall current is 1.6A.
I've read that motors draw close to their stall current when starting up, although it is only for a short time.
Should I choose my regulators based on stall current or nominal current?
Thank you for reading, any input would be appreciated.


texts: Schematic Design and Non-PCB Mounted Components

texts:
I am working on a bipolar power supply for hobby and educational purposes.
Concerning the schematic, is it possible/good practice to place devices that don't go on the PCB in the schematic?

Specifically, I have chassis mounted connectors, TRS and XLR, along with a chassis mounted transformer. Should/Can these be shown on the schematic without generating nets for their connections? The transformer primary, power inlet connector, and fuse are all point-to-point wired, with only the transformer secondary entering the PCB. Should these point to point connections be shown?

If its of any importance, I'm using Proteus 8.


texts:
I’m building a mains sensor that should be able to operate safely at a voltage of up to 650VAC. I’ve already built one before, that operated with 130VAC, which I successfully monitored with a MCU, and printing the results onto the serial monitor on my laptop. Later I built it on a PCB with copper dots, same schematic, but this time I connected it to my dads computer, and guess what, it blew up. But it worked on my laptop (although it was a breadboard version), which is because the laptop is battery powered, right?
I UNDERSTAND THAT EXTREME CARE SHOULD BE TAKEN WHILE DEALING WITH SUCH HIGH POWER/VOLTAGE. AND THAT IT CAUSE SERIOUS BURNS AND DEATH! I KNOW IT SOUNDS LIKE I DID NOT TAKE CARE WHEN THE COMPUTER BURNED, BUT IT WAS MY LACK OF KNOWLEDGE. I AM WILLING TO ACCEPT ANY ADVICE YOU GIVE ME. SECURITY IS PRIORITY.

I used a bridge rectifier capable of 800VAC 1A. The capacitor is electrolytic 1000uF 16V. The resistors are 2W (I use 4, schematic shows only 2 for simplification) and values are chosen to get specific voltage.
So do I only need a Zener Diode or do I need more? Optocouplers?

Edit
I want to use this sensing to monitor the voltage and if it goes under the preset value of a pot, it should cut the supply to the device or motor that is connected.
Any positive advice is greatly appreciated!


texts: Which should I use? Stepper or DC motor?

texts:
I have a project where I have to sweep a windshield wiper about 90° at a rate of 150 sweeps/minute. (~3 sweeps/second)
Since the sweep rate is high, I was thinking of using a stepper motor to get it done.
I will get the specs of the wiper soon after which I may be able to estimate the voltage,current and torque requirements.
But I need advice regarding the motor and driver choice since the project timeline is short and we cannot afford to make mistakes.
Edit: I'm a bit inclined towards a stepper motor due to it's speed and sweep controllability, though will it be able to accelerate and decelerate the load at such a high rate?
Edit: I realise that the windshield link mechanism to convert rotational motion into sweeping one would be a much better approach and a brushed DC motor would do the job nicely. So the only challenge remaining is getting enough torque and rpm out of it.
P.s I checked some wiper motors, they have 55 rpm with 40 kg-cm torque


texts: How i could find how program existing board with atmega chip on it

texts:
I have few "lego" roborobo sets (http://www.roboroboglobal.com/products/robokids1.html)
I'd like to find way to upload programs there written on PC.

On unit have ATMEGA16L chip and 6 pinholes with markings (Gnd, J3, VCC).

Another - ATMEGA64L, and RJ11 (marked J3) for programming.

J3 probably means one of the external connections types, as there are more J connectors (RJ11).

There is also kind of programmer, that also have RJ11 socket, and used to program 2nd unit with barcode cards. It have ATMEGA8L chip on it.

What software/hardware/components do i need to write and upload program there?

I wonder if I could make something that could be used by kids to learn programming. Set have buttons, leds, motors, but without possibility to upload programs, it would be nearly impossible to utilize it.

I'm very new to electronics, and only know how write simple things for arduino.


texts: Using BJT transistor as switch using arduino digital pin

texts:
I was working on a project and decided to use a BJT transistor as a switch. I haven't taken the electronic circuit courses which deal with transistors in my university yet so I wanted some advice if my idea is feasible or not.

Basically, I have an actual switch (Pololu Pushbutton Power Switch SV) that will control when my project will be turned on and off. But my device will be hooked onto a bike so I made it so that if an RFID tag is properly read (via an RFID reader), my BJT (which is in series with the battery source and the pololu switch; please see google doc for schematic) will be allowed to conduct current across it, hence powering the device. When the RFID tag is properly read, I will set a digital pin to HIGH (this pin is connected to the base of the BJT transistor) which will allow the current from the battery to flow across the BJT and power the the device. Will 40 mA delivered to the base be enough for current to flow across the BJT?

Here is my circuit diagram I have quickly drawn (it's located in a google doc folder):
https://docs.google.com/document/d/1H8ES5edi69eQtyavTgFldQ_BlMkgLi44-MLGMWAWi6Y/edit?usp=sharing

Thank you for anyone who comments and please don't hesitate to ask me for more info! Since I have been researching BJT transistors on google, my knowledge on them is not concrete so please forgive me if I have some silly/stupid assumptions or I am totally doing this the wrong way.

As requested, here is the switch:
http://www.pololu.com/product/750

Just some back ground for you guys on why I am doing this. This is so if someone tries to attempt to close the device when it should be operating, the device will still be operating since the digital pin is HIGH and current is still flowing accross the BJT transistor hence allowing the device to be still powered up. If the user wants to shut the BJT off, just swipe the correct RFID tag again and this will cause the digital pin to become LOW which will cause the BJT to stop the flow of current.


texts: Maximum cells in a row in a SRAM memory array

texts:
I was considering designing an SRAM memory array. For my design to be useful in a certain system, I need to have several cells in a row (e.g. 1024, 2048).
In textbooks I have seen examples of arrays with typically 8-cell words (1 byte per word).
Is it possible to have as many as 1024 cells (128 bytes) in an SRAM word?

One problem that comes to mind immediately is that driving such a long word-line may require big drivers. But this would be design problem, not a fundamental one.

Could there be any other issue?


texts:
I have an electronic drumkit, which is plugged to the AC plug.
I want to put it in a room without any access to the AC grid, and I would want to use batteries instead.
The device is called Roland Td15, and from what I read in the manual, it uses a DC 9V, with 450mA current draw. Here is a link to the complete pdf manual. It says the adapter used is "PSB 1U".
My question is how to use a battery (or AA batteries if possible) ? Is it as simple as getting 6 AA batteries in series with the right DC plug ? Are there some point I should be aware of ?
I saw products like this one, maybe it is enough, what do you think ?
Have a nice day !


texts:
I have a problem with a battery booster/charger circuit, that I really can't figure out and I hope that somebody can help me.

This is the circuit:

When i connect a 3,7V battery at  X3-2 and X3-2 the TPS61200 quickly gets very hot. However it is still working and outputting 5V. At the moment the TPS output is not connected to anything.

There is no USB connected to the USB-POWER supply.

The circuit is based on the following schematic:
http://cdn.sparkfun.com/datasheets/Prototyping/PowerCell-v13.pdf

Can anybody help me?
Thanks!

UPDATE 1:
I meassured the 5V output with an oscilloscope and got the following result:

It seems like the TPS cuts off repeatedly (maybe because of internal thermometer?). It cuts off at 5.8V, and drops down somewhere between 1-2V.

I also meassured while driving a DC motor and got a similar result:

Here is the PCB-layout from eagle:
Top

Bottom

I have also taken some pictures of the board:
Top

Bottom


texts: Motor controlled using Rpi 3 and 12V power supply

texts:
Could someone please assist me with the below circuit? I can't seem to get it to work. I am using a 12V power supply and Raspberry Pi 3. Apologies, I am very new to circuits. The DC motor does not turn on, when I run my script.

Motor specification:

Operating Voltage : Between 6 V and 18 V
Nominal Voltage : 12 V
Free-run speed at 12 V : 22 RPM
Free-Run Current at 12 V : 50 mA
Stall Current at 12 V : 1200 mA
Stall Torque at 12 V : >24 kg·cm
Gear Ratio : 1:377
Reductor Size : 27 mm
Weight : 94 g


texts:
I'm trying to figure out a way to optimize the power consumption of a group of two high-side switches. They are not supposed to be switched more than once every minute.

I don't know if my way to connect them is right. I have two loads (both constituted of step-down and step-up voltage regulators, electronic speed controllers, etc). The goal is to command them by manual switches. There is a pull-down resistor on each MOSFET's gate (if one of the switch has a malfunction, the loads are still working).

If the load 2 is turned off, load 1 should be automatically turned off (thanks to the diode).

Loads are between 10 and 60 amps. (The load values are for illustrative purpose)

I have several questions:

I chose P-Channel MOSFETs (IPD042P03L3), they probably increase the power loss compared to a N-Channel MOSFET. Is there another "easy" way to have the same functionnality without P-Channel MOSFETs ?
In the datasheet, they say the Rds(on) is about 4.2 mOhms for Vgs = 10 V (Vgs should be higher that 10 V in this circuit), that seems a decent value to me, am I right ? If my calculation is right, the power loss would be about 0.25 W for a load of 60 Amps.
I decided to use the same MOSFET for both loads, the reason is that I didn't see any other P-Channel MOSFET with a lower Rds(on) on Digikey. Should I use a MOSFET rated for a smaller current ? My guess is that the gate charge could be smaller with a smaller MOSFET, but does that really matter if I only switch once in a while. Is there any parameters that does matter in my case ?
The pull-down resistor is about 1k. If I increase it, that should reduce the power consumption but how do I know how far I can go ?

Thank you in advance,

Please feel free to comment the design !

EDIT 1

I updated the design with the P-Channel MOSFETs that Russell was talking about.

The voltage source is a 4-cell LiPo battery (voltage goes from 12.8 V to 16.8 V), I use a Zener diode to keep the minimum value of Vgs at around -10 V regardless of the voltage source.

The Zener diode I chose is the MMBZ5240BLT1G. When switch is open, the current through the Zener diode is between 0.9 mA (Vsource 12.8 V) and 2.3 mA (Vsource 16.8 V). Power dissipated by the zener diode: between 9 mW and 23 mW (far below 225 mW).

With this design, Rds(on) should stay below 2mOhms... Power loss would be about 7 W for a maximum load of 60 Amps (load values on the schematic are for illustrative purpose only !).

Keep posting your comments on the design ! Thank you very much !

EDIT 2

I'm thinking about another aspect of this design.

In the case the MOSFETs are turned off during a long period of time (over several months).

Since the system is powered by a battery, it may be a good idea to reduce the quiescent current to a negligeable value.

For example, in the previous schematic, the current needed by the resistors when the switch is closed is about 2x (16.8 V / 3000 Ohms) = 11.2 mA. For a 4-cell battery of 5000 mAh, that means the battery will be dead after 19 days (and probably much less than that).

I don't think I will implement it in the first design of this board but how is it possible to reduce the quiescent current ?


texts: Temperature and flash corruption in microcontrollers

texts:
I'm repairing quite the pricey device, where a strain gauge failed. It's a pressurized device, and the strain gauge measures the internal pressure by means of it. The crux of the matter is that the strain gauge goes on a small metal cylinder epoxied to the PCB itself.

To install a new one, I will need to use hot curing resin, but I want to avoid having to remove the metal cylinder to reduce risks of damage and potential surprises. This means baking the whole PCB, MCU included, which worries me a lot since I have no clue whether it could become corrupted and I can't reprogram it.

I have 3 options for hot curing with Adhesive A:

1 hour at 190 °C
3 hours at 170 °C
6 hours at 160 °C

And other 3 with Adhesive B:

30 minutes at 200 °C
1 hour a 180 °C
3 hours  a 150 °C.

Now, the max storage temperature I saw in the datasheets of some ICs on the board is 125 °C which is what is deterring me from attempting this.

I found this question that basically asks the same, but I'm looking for a more formal resource if anyone has one.

I'm also thinking if there's a possibility of insulating the rest of the PCB since the topology allows it.

Thank you very much in advance.


texts:
I finally finished my first transistor circuit and looks as follows:

For the LED to light up properly, I assumed a forward current of 70mA and a voltage drop of 1.3V. The datasheet of the PN2222A states that at 70mA collector current, the saturation voltage \$V_{CE}\$ will be about 0.06V. So
$$
R2 = \frac{5V - 1.3V - 0.06V}{0.07A} = 52\Omega
$$
Lowest value of \$\beta\$ equals 10, resulting in a total minimum current gain of
$$
\beta_{Total} = \beta^2 + 2\beta = 120
$$
\$I_{B}\$ is therefore
$$
I_{B} = \frac{I_{C}}{\beta} = 583\mu A
$$
So
$$
R1 = \frac{3.3V - 1.62V}{583\mu A} = 2882\Omega
$$
When I plugged in both voltage sources, the LED only glimmed lightly. I measured \$I_{C} = 42.4mA\$ which is definitely too low. For troubleshooting purposes I checked every voltage drop and one was far away from its theoretical value: \$V_{CE} = 0.7V\$.

Why is the real saturation voltage way higher than stated in the datasheet?


texts:
I'm trying to set LOC constraint while specified in verilog code (via verilog attribute). Previous research on the internet gave reasons to think that this sort of construction should work:

///////////////////////////////////////////////////////////////// code begins

module wrapper(in, out);

    input in;

    output out;

    (* BEL="A6LUT", LOC="SLICE_X4Y4") INVERT inverter_instance1(in, out);

endmodule

module INVERT(in, out);

    input in;

    output out;

    assign out = !in;

endmodule

///////////////////////////////////////////////////////////////// code ends

Yet when implemented, Vivado just ignores that attribute syntax and implements the LUT into slice X0Y1 by default. Any thoughts on what's going on here?


texts: what type of internal memory do most digital cameras use? (not talking about SD cards or other removable storage)

texts:
I am looking into something for work and I need to know what type of flash-memory storage is most common in digital cameras so we can look into how to properly eradicate all of the data on the cameras's internal storage. I understand that there is more than likely not just one type of flash-memory in all cameras, but this is proving to be a difficult question to find the answer for, as all of my searches come back with information pertaining to the SD card for the camera. I am also trying to find out if a simple overwrite will be sufficient to ensure the data is permanently erased. these questions are aimed at digital cameras that were manufactured from 7 years ago to the present.

  -Thank you in advance!


texts:
I am currently using ST32L152RE controller interfaced with BLE CC2640R2F module and 4 MB external flash memory interfaced through spi. I was trying to upgrade the firmware of my st controller using BLE. My approach is to receive firmware using BLE and store it in flash memory, then ask controller to restart and execute the code written in flash memory.

As far as I think there are two possible ways.

I need to copy that code file (binary data) from external flash memory to controller flash memory then reset the controller so that it execute the code written in internal flash.
I will ask the controller to directly execute the binary file or code file from external flash memory. (I have no idea if this will work or not)

I am taking an assumption of possible ways to get the results. Very confused if any of this approach works or not.


texts: is any other technology than semiconductor transistors or vacuum tubes that can be used as active devices?

texts: I am curious to know if one can amplify a signal or make nonlinear active distortion to an electric signal without semiconductor transistor or vacuum tube technologies?


texts: Can voltage be controlled in a fixed DC circuit?

texts:
If resistance is fixed in a DC circuit, can voltage still be controlled and changed from one value to another?

Imagine this circuit, that has a fixed resistance of 1 Ohm, and the desired current is 20A, If the power supply is 100W, what would the voltage be? 5V?
If so, what about ohms law? V = IR? And P = IV?

I'm confused because I thought that voltage and current can be controlled to whatever value required, using a power supply. The resistance of the circuit is the most important thing isn't it?

Another example:
A 20,000W power-source, and the resistance of the circuit is fixed at 0.001 Ohms, can the power supply control the voltage to any value required? 2V, 10,000A? Or any other combination that does not exceed 20,000W? 20,000V at 1A? The same resistance of 0.001 Ohms?


texts: Is there any solution to high-precision high-side sampling current measurement?

texts:
I want to do some high-precision current measurement. (Voltage up to 20V and requires current to be shown in 0.1mA resolution, current can be up to 4A). The simplest is low-side sampling by MCP3421:

simulate this circuit – Schematic created using CircuitLab

This one is easy and accurate. But this breaks the ground connection.

Using MCP3421 for high-side sampling is not possible, because it will break its input voltage limit(VCC + 0.3V). Our upstream voltage can be up to 20V.

Another possible solution is by using OP-Amps:

Link to pdf

Page 18 describes how to use OP-Amps to do the conversions. But I wonder the resistors can be inaccurate and ageing is a killer of accuracy.

There's one more solution: using high side current sense amplifier like TSC101 or LTC6101. But this sort of ICs often has a high Input Offset Voltage (Vos) up to approx. 1mV. 1mA on 15mOhm sampling resistor is 15uV, so the offset seems to be unacceptable.

Are the above solutions possible? Or are there any other solutions?


texts: How does the resistance of the load affects a voltage divider?

texts:
Every explanation I've seen so far about voltage dividers, only consider the two main resistors (that do the "dividing"), and pretty much ignore what happens after Vout.

The circuits in the explanations look more of less like this:

In this example the voltage at Vout should be 2.5V.

This really gives the impression, that whatever goes on for the rest of the circuit, Vout is at 2.5V.

But what happens in practice, if I get something connected to Vout? E.g, I connect some components, and their equivalent resistance is 100Ω:

Since R2 and R4 are in parallel, an equivalent resistor would be of 50Ω. Now, if that's correct, then the voltage divider really operates between a 100Ω and a 50Ω resistor. I.e. the voltage at Vout would be 1.67V and not 2.5V, as I originally wanted it to be.

Is this really how it works?

How should one design the part that connect to Vout to avoid messing up the divider?


texts: Often times I read comments/recommendations about placing lots of vias for GND in 4-layer designs, as well as a line-up of vias surrounding the board to protect from EMI, etc. I was always under the impression that vias (either tented or not) have a certain impact in the final PCB cost, so I tried to minimize their numbers in my designs. However I might have been wrong and vias are extremely cheap? For instance, in a 4"x4" board, how much would it affect a design cost to have 400 or 200 vias instead of 100? Does the diameter of the via matters? I'm talking about normal all-the-way vias, not buried vias which I know are much more expensive.


texts: COM differences between input and output in PLC

texts:
See below for a wiring diagram of the I/O of a PLC (model: Omron CP1L).

Input:

Output:

What does the input side has many input but only one COM, but on the output side there are more COM grouped with one to a few output point?


texts:
I try to build a RF amplifier using the CGH40010F HEMT. The amplifier should work between 2.4 and 2.5 GHz and I would like to have at least 5 Watts of output power. While I was searching for information on designing such an amplifier, I found this article

http://www.highfrequencyelectronics.com/May11/HFE0511_Grebennikov.pdf

which I found very interesting and helpful. As far as I understood, the trick with class F is to connect a network to the drain of the transistor, and the network's impedance shall be infinity for odd harmonics, and zero for even harmonics, such that the voltage becomes a square wave. These two IEEE papers give nice information how the output power can be calculated:

F. Raab, “Class-F power amplifiers with maximally flat waveforms,” IEEE Transactions on Microwave Theory and Techniques, vol. 45, no. 11, pp. 2007–2012, 1997

and

F. Raab, “Maximum efficiency and output of class-f power amplifiers,” IEEE Transactions on Microwave Theory and Techniques, vol. 49, no. 6, pp. 1162–1166, 2001.

So, I designed my load network as follows

where the two radial stubs and the 90° lines present an open circuit at the operating frequency. The impedances Z1 and Z2 are chosen such that the 50 Ohms load is transformed to the impedance

$$ Z = \frac{4\,V^2}{6\,P} $$

where P is the desired output power. This equation can be derived using Raab's 2nd paper. I then simulated the network consisting of the 90° lines, Z1 and Z2 in Microwave Office. The transistor was neglected for this first simulation. The simulation shows that the network works as desired: a low impedance is presented to even harmonics, and a high impedance is presented to odd harmonics. At the fundamental, the impedance seen is as calculated above.

However, as soon as the FET is connected to the network, this can no longer work correctly because the FET has a parasitic capacitance from drain to source, which detunes the loading network. What can I do to compensate for the CDS? The article I linked above gives some hints, but I do not understand them.

ADDED INFO:

(from comments done by the OP)

This is what I simulated in MWO:

The input impedance at port 1 is important. I need 38 Ohms at 2450 MHz, 0 Ohms at twice the frequency, and infinity impedance at the triple frequency, as shown here:


texts: Creating a Programmable ROM Logic / Schematic

texts: I would like to know if it is possible to create a programmable ROM from transistors and logic gates? Or, is it possible to create a type of persistent storage similar to Flip Flops?


texts:
I have an ARM board which uses a VIO of 1.8V .I need to use one of the ARM pin as enable to other device that need to enable with 5V.
How i can do it with this FET( i prefer to use this one cuse he is small and i already used him in other place in my board).
enter link description here

thanks


texts:
I have just started experimenting with electronics and am concerned that I may have destroyed my LM339 comparator circuit. As a basic test, I had a 3.0 volt power supply hooked up to the Vcc pin and one of the + input pins. Nothing was hooked up to the corresponding - input pin. The long leg of the LED was attached to the corresponding output pin with a 1kohm resistor in between. The short leg of the LED was attached to ground but the comparator GND pin was not. I expected the LED to light up when I flipped the power switch.

When I flipped the power switch,  The LED flashed briefly and then went off. After this incident, I verified that the LED was still working. Now I am trying to figure out if the comparator is broken. How can I do this using my multimeter? What are some basic tests I can do to figure out if the comparator is working properly?


texts: Some confusion about differential-ended data acquisition system

texts:
I have many transducers which all have single-ended signal outputs. I hook them up to a single-ended DAQ board. A board with 16 single-ended inputs. The DAQ bard is currently set to single-ended configuration, but can also be set to a differential-ended configuration.

For noise reduction I'm considering to use the DAQ board in differential ended mode.

As far as I know, a differential signal outputs SIGNAL LO and SIGNAL HI electrically floating with respect to ANALOG GROUND.

I some confusion and have the following questions:

1-) Do I need to buy new transducers which output differential signals if I were to use a differential-ended data acquisition board?

2) If so, is there an alternative way to convert a single-ended signal to a differential-ended one?

3-) If I use a  differential-ended data acquisition board with single-ended signals without common grounds would it be also OK to reduce the noise?

edit: I think there are transducers which output mirrored signals as SIGNAL LO and SIGNAL HI. And there is also Differential Connection of single-ended transducers which has Signal and GND. This is the source of my confusion.


texts: Identifying a bluetooth development device

texts:
This is some kind of bluetooth development device and I want to find out if this can be used with BlueLab software suit, but cannot find more details on it

The main chip is BlueCore BC358

The area in the green box has some kind of logo ( I think it is the logo of CSR, as a similar logo appears on the BC358 chip as well) with some text DEV-PC-1324C and usb391 on the next line (it is a bit hard to make out)

Using the drivers I get in my BlueSuit installation, Windows 7 detects it as CSR USP<>SPI converter

I want to see if this can be used with BlueLabs for Bluetooth development or not ( I am a complete beginner with Bluetooth and BlueLabs right now)

Could someone please provide the name of this device and any kind of details on it?

(It was bought online from China, if that helps)

EDIT1:


texts:
I have a simple register based clock divider component I can drop in when I don't have a spare PLL:

library IEEE;

use IEEE.std_logic_1164.ALL;
use IEEE.numeric_std.ALL;

entity div128 is
    port(
        inclk0 : in std_logic;
        locked : out std_logic;
        c0 : out std_logic
    );
end entity;

architecture syn of div128 is
begin
    div : process(inclk0) is
        variable counter : unsigned(6 downto 0);
    begin
        if(rising_edge(inclk0)) then
            counter := counter + 1;
            c0 <= counter(6);
        end if;
    end process;

    locked <= '1';
end architecture;

Now I'd like to reuse this component in multiple places, in different clock domains, without repeating myself more often than strictly necessary.

Do I need to create a create_generated_clock statement for each instance, or can I specify once that each instance generates a -divide_by 128 clock from its input?
Could I also pull the divider from a generic parameter and take it over into the timing constraints?
Would it make sense to use attributes here instead of an SDC file?


texts: Motorized valve interfering with button?

texts:
I have the following circuit:

The relay will basically be controlled by the Arduino (using pin 3), based on a value it's getting (from a NRF24L01 module). However, I also want the relay to be controllable via a button.

Problem:

Controlling the relay with the button is working fine WITHOUT the load (a 3-way motorized valve) being connected. When the load is connected, the button gets randomly pressed WHILE the valve is moving.

Based on this observation, I guess the 3-way motorized valve interferes with the button. Sadly, I cant figure out how to solve this error. I've spend several hours, with no success. Some things I've tried:

add flyback diodes around valve
attach the button in different ways
tried placing resistors
seperate the relay circuit from the rest, as it should ideally be (I was not succesfull doing this, because the transistor must be connected to the common ground? + the Arduino has the same power source as the 3-way valve..)

Another solution is (I think obviously) to seperate the relay circuit from the rest. But I can't figure out how to split the 12V power supply into two seperate power sources.

My temporary solution...

Since the button only gets randomly pressed WHILE the valve is moving, I've written my code to ignore the button during valve movement. I consider this as a temporary solution. I want to understand what exactly is going on and how to solve it.

Is the motorized valve interfering? How to solve this problem?


texts: Stepper motor controlled by turning only in one direction and stalling in opposite direction

texts:
I am controlling a high-torque stepper motor (23Y204S from Anaheim Automation with 8 lead-wire) using a microstepping driver (MBC15081) and Arduino.

The winding wiring is connected as bipolar series connection. The Arduino was programmed and the motor works fine in one direction, however, it stalls when trying to rotate in the opposite direction (it is possible to feel the pulsing/jerking) and it does not rotate.

I am currently using the driver in the sinking mode and it says that to control the direction of the rotation, it is necessary to change the signal from Logic '1' to Logic '0' and vice-versa. As you can see in the code below, in the forward motion (when directionPin is HIGH) the motor rotates, but in the reverse direction (when directionPin is LOW - in the code below it is highlighted with "stars" ****) the motor stalls.

Please share your feedback about this.

Arduino Code:

P.S: The Serial.Read is receiving data from Visual Studios. Does not affect the problem here.

int clk = 27;
int directionPin = 34;
int MS2 = 42; //dip switches for step setting
int MS1 = 43;
int power = 35; // ON/OFF

const int revSteps[] = {3200, 800, 400, 200};
const int MS2switch[] = {LOW, LOW, HIGH, HIGH};
const int MS1switch[] = {LOW, HIGH, LOW, HIGH};

void setup()
{
  Serial.begin(9600);
  pinMode(clk, OUTPUT);
  pinMode(directionPin, OUTPUT);
  pinMode(MS2, OUTPUT);
  pinMode(MS1, OUTPUT);
  pinMode(power, OUTPUT);
}

void loop()
{

  while (Serial.available() > 0)
  {
    char cat;
    cat = Serial.read();

    if (cat == '1') //Forward
    {
      digitalWrite(power, HIGH); //Turn motor ON
      digitalWrite(directionPin, HIGH); //counter clockwise
      digitalWrite(MS2, MS2switch[0]); //full/half/quarter/eighth of step
      digitalWrite(MS1, MS1switch[0]); // ""
      for (int x = 0; x < revSteps[3]; x++)
      {
        digitalWrite(clk, HIGH);
        delayMicroseconds(3000);
        digitalWrite(clk, LOW);
        delayMicroseconds(3000);
      }
      digitalWrite(power, LOW); //turn off motor
    }

    else if (cat == '2') //Backward
    {
      digitalWrite(power, HIGH); //Turn motor ON
      digitalWrite(directionPin, LOW); //clockwise - DOES NOT WORK  *************************************************
      digitalWrite(MS2, MS2switch[0]); //controlling speed of motor
      digitalWrite(MS1, MS1switch[0]); // ""
      for (int x = 0; x < revSteps[3]; x++)
      {
        digitalWrite(clk, LOW);
        delayMicroseconds(3000);
        digitalWrite(clk, HIGH);
        delayMicroseconds(3000);
      }
      digitalWrite(power, LOW); //turn off motor
    }
  }

}


texts: I have an induction motor running hot and slow in the direction it's supposed to but when I change the lead wires so it runs in the opposite direction it runs as it should. Is there any reason as to why? Could it be a problem with the capacitor? It's a single-phase 200V.


texts: Is operating point calculation the same for P-JFET and N-JFET with voltage-divider bias?

texts:
I've seen this calculation of operating point for N-JFET:

Together with the relation \$I_D = I_{DSS}(1-V_{GS}/U_P)^2\$, it is possible to find \$I_D\$ and \$V_{SD}\$.

This method doesn't take into account that it's a N-JFET. Does this mean that the result would be identical for a P-JFET? (I think it is, because we assume that there is no current through the gate, so P/N-ness wouldn't matter.)


texts: If a microcontroller I/O pin drives an external MOSFET, and the microcontroller's power is turned off, will that MOSFET's gate be floating? I know sometimes a resistor is added to ground, but are there risks if I don't place the resistor?


texts: How sensitive are laptop barrel jack sizes?

texts: In particular, is a barrel jack described as 1.35mm x 3.5mm likely to work with a socket made for a 1.3mm x 3.4mm jack?


texts:
I've bought many MBI5026GF driver ICs.
based on the datasheet, the IC set up with MCU and other components is very similar to 74HC595 (Serial to parallel procedure) but with 16 bits of data per IC.
but I don't understand how the LE pin works. (it's supposed to make the latching happen.)
the pin description is not clear to me. (when it gets low data is latched to output pins ? or when it's low?)
which way is correct to code my mCU ?

set LE low. send serial data. set LE high.
set LE high. send serial data. set LE low.

should OE be always low when all these happens ?
Datasheet Link


texts: How to apply nodal analysis when value of dependent voltage source depends on current of a plain wire?

texts:
Need to find out the value of V11 (V11 = 4*I9 Volt), as it's a dependent source and it's value is depending on the current through the plain wire W9 of no resistance. I solved this with Mesh current analysis method but I need to learn to be able to solve this using node voltage analysis method too.

Answers from mesh analysis currents and voltage drops of the elements.
I2 = 7 A & V2 = 280 V
I4 = 8 A & V4 = 40 V
I11 = 18 A & V11 = 40 V
I7 = 8 A & V7 = 80 V

My problem: While solving this with node analysis, as this problem belongs to supernode method application where we form 2 equations, one of which is given by difference of the two end nodes equals the voltage source for which I need value of I9 to be written in voltage form. Which I do not know how to form.

Update 2: I learned from some answers here that, it is possible to find the current and voltage values of each element without having to convert I9 to voltage form. Got the answers but they don't match the answers i got in mesh analysis method. Here's what  I did.

Considering bottom node as reference and other nodes 'node a', 'node b' and 'node c' respectively from left to right and Vc=-240, I got these two equations..

node a + node c gives
(-19 + Va/40 + (Va-Vb)/5 + Iac) + ((Vc-Vb)/10 - Iac)= 0
=>-19 + Va/40 + (Va-Vb)/5 + Iac + (Vc-Vb)/10 - Iac = 0
=>0.025Va + 0.2Va-0.2Vb -24-0.1Vb = 19 since (Vc=-240)

0.225Va - 0.3Vb = 43 ------(1)

node b eqn.
(Vb-Va)/5 - 2*(Vb-Va)/5 + (Vb-Vc)/10 = 0
=>-(Vb-Va)/5 + (Vb-Vc)/10 = 0
=>-0.2Vb+0.2Va + 0.1Vb-0.1*-240 = 0

0.2Va - 0.1 Vb = -24 ------(2)

Giving me Va=307V and Vb=373V, giving voltage drop across R4=67V which is not the same as returned in mesh analysis method i.e. 40 V.

Please help me get it right or suggest me where I'm going wrong.

Thank you...


texts: How the below verilog code run when it find positive edge of clock?

texts:
rd=1;
case1=2 ;
i=2;
n1=23;
always @(posedge clka)
begin
    counter=counter+1;
    if (rd==1) begin
        #5 window[i]<=douta;     ~~~~~~~~~~~ Statement1
        case(i)
            case1: addra=n1;
            case2: addra= n2;
        endcase
        #5 addra<=addra+1;            ~~~~~~~~~~~Statement2
        #5 i<=i+1;
    end
end

The statement inside always block in verilog is sequential. At the positive edge of clock :

counter=counter+1
if (rd==1) (true)

Confusion: My confusion is that as case statement is occur first because window[i]=douta (after 5 unit time). After this statement 2 occur or statement 1 and statement occur at same time.

Please anyone clear my doubt after how statement inside always block in this case run.
Thank you


texts: Preventing reverse polairty in NiMH batteries

texts:
So, I am powering The Device.  It's low power, running at <10mA.  Minimum voltage required is 3.5V, so using NiMH rechargeable batteries you need 4 in series.

My problem is that they discharge, leaving 3 at ~1.1V and the final battery at 0.02V, ish.  This is bad for the battery - but I can't see any way of preventing this.  All the reverse polarity suggestions I've seen appear to care about protecting The Device.  I want to care for my batteries!

Ideas?


texts: Microchip PIC24's DMA doesn't work as expected

texts:
I am trying to configure the DMA in Microchip's PIC24FJ1024, DMA channel will transfer Data, from Source to Destination, every time the program trigger the DMA Channel.

One Shot Mode
SRC increments every transfer
DST address increments every transfer
DMACNT0 = 2

I have written this simple code to test the DMA

#include "xc.h"
#include <stdio.h>

#pragma config FWDTEN = OFF

int ArraySRC[100];
int ArrayDST[100];

void DMA_Init (void)
{
    DMACONbits.DMAEN = 1;//enable dma
    DMACONbits.PRSSEL = 1;//channel priority

    DMACH0bits.NULLW = 0;//no dummy
    DMACH0bits.RELOAD = 0;//don't reload
    DMACH0bits.SIZE = 0;//word

    DMACH0bits.SAMODE = 1;//SRC address ++
    DMACH0bits.DAMODE = 1;//DST address constant

    DMACH0bits.TRMODE = 0;//one shot

    DMASRC0 = (int) &ArraySRC;
    DMADST0 = (int) &ArrayDST;

    DMACNT0 = 2;

    DMACH0bits.CHEN = 1;//enable channel
}

int main (void)
{
    int i;
    for(i = 0; i<100; i++)
    {
        ArraySRC[i] = i+1;
    }
    DMA_Init ();

    //1st trigger
    DMACH0bits.CHREQ = 1;//start transaction
    while(DMACH0bits.CHREQ);

    //2nd trigger
    DMACH0bits.CHREQ = 1;
    while(DMACH0bits.CHREQ);

    while(1);

    return 0;
}

What I expected was, was for every trigger DMACH0bits.CHREQ = 1; the DMA updates the SRC, and DST address, and decrements the DMA Counter DMACNT0.

But when I debug it (using the simulator), the debugger reaches the first trigger, updates the SRC, and DST (I can see it in the variable window), but when it reaches the second trigger, the debugger stops at while(DMACH0bits.CHREQ);, and the DMA Counter remains 1, and doesn't decrement.

Any help would be appreciated.


texts: Issue with daisy chained arduinos and serial communication

texts:
I have a setup with a 32U4 based board and 2 daisy chained 328p based boards.
Boards are connected via 4 wires : VCC, GND, TX, RX
32U4 is powered by USB
Daisy chain is :
32U4 (RX)  <- (TX)  328p (RX)  <-  (TX) 328p
32U4 (VCC) -- (VCC) 328p (VCC) --  (VCC) 328p
32U4 (GND) -- (GND) 328p (GND) --  (GND) 328p

The 328p boards are sending every 1s a message on their uart TX port which is received by the board on their left.
Process is running ok but I have this strange behavior : when I upload a new version of the sketch on the 32U4 (via USB) and without powering off/on the serial messages chain get somethimes broken. This does not happen if I switch the 32U4 on/off.
Do you guys have an idea on why a sketch upload (reset) would produce such a behavior?
Thanks.


texts: Is it possible to make an IGBT to work at duty cycles up to 100%?

texts:
I am designing an IGBT based chopper with single Low side switching IGBT (chosen low side switching because ease of driving the IGBT.)

There are plenty of resources available for SMPS (buck, boost, buck-boost,) PFC chopper, inverters, welding power sources, UPS and motor control applications. I presume all those applications work under duty cycles up to 50% and for motor applications it may go up to 95% (only during the peak of the SPWM signal) but none of the applications mentioned made it to work continuously in the duty cycle range of 90% or above.

I googled a lot and read the application notes, datasheets and reference designs of various IGBT/MOSFET manufacturers such as Infineon, ST, Semikron, Vishay, ROHM, Fuji, Mitubhishi, Hitachi, Toshiba, IXYS, ABB, Renesas, TI, NXP, Nexperia.

Some of the applications listed below which uses IGBT close to 100% duty cycle operation.

HVDC circuit breaker  uses a hybrid approach. During operation the current will always flow through the bypass branch which has a mechanical circuit breaker and during the interruption of  the current it will be allowed to pass through the IGBT, this application doesn’t help me to understand about the 100% operation of the IGBT.
Another application which uses the duty cycle up to 100% is separately excited DC motor which can use IGBT, but I couldn’t find any reference for the implementation  using IGBT and there are plenty of resources available for thyristor based choppers and simulation of the same.
The DC electronic load which uses the MOSFET in DC operation and couldn’t find reference for high power electronics load using IGBT.  Many of the manufacturers of IGBT mentioned not to operate the devices in the linear region.

I am intending to use IGBT modules of 1200V/400A (semikron SKM400GB125D half bridge module.) For the proof of concept I used discrete IGBT (IRFGP50B60PD) and drove it up to dutycycle of 50% @ 490Hz and it worked perfectly.
The high power IGBT modules the manufacturer doesn’t provide FBSOA but  they provide RBSOA and SCSOA details alone. For the short overload conditions recommend to refer the  transient thermal impedance characteristics and for the steady state pulsing operations recommends to look at RthJ-C of IGBT & diode.

Many manufacturers have simulators which allows to simulate the electrical and thermal details of our circuit, but for which I couldn’t get some pointers regarding how far the simulation and bench test correlates (correlation of simulation Vs implementation) Semikron Semisel, Infineon (uses PLECS,) Fuji electric.
  By the simulator, we can estimate the losses of the switch (switching loss and conduction loss) and junction temperatures.

For the following questions I am expecting some inputs from the community:

Is it possible to operate IGBT up to 100% duty cycle? I couldn’t find many application references for IGBTs, which works in the duty cycle close to 100%. The question is similar to https://www.researchgate.net/post/Can_the_IGBT_MOSFET_turn_on_all_time_long_just_as_a_diode
Need some information regarding how far the simulation and bench test correlates (correlation of simulation Vs implementation.)
Reference designs or some resources for DC chopper using IGBT/MOSFET.
Suggest me some technical forum and resources dedicated to power electronics.


texts:
My CF card has been corrupted. I don't know how is that happened. I just using new card (five months old) on EOS 5D Mark II with installed Magic Lantern. The card just not see as USB device on my PC. And DSLR not launches with this card.

Very possible the controller was damaged, but I not sure. Memory can be damaged too?

In restore service they told me the there are read errors while trying reading via USB (low-level reading) (and requested much money :D)

I want to get info from this manually. How is that possible? (Using hardware programmer device? Another controller? I need more info)


texts:
I've got a test bench for brushless DC motors, which is supplied with a regulated power supply unit. The motor itself is driven by an electronic speed control (ESC), which feeds energy back to the power supply when actively slowing down the motor (regenerative braking). My power supply cannot sink current, which leads to non-transient high voltages when braking or spinning down. This would damage the test bench's measurement equipment, causing it to terinate the test run.

I have (unsuccessfully) tried to sink the power into a MOSFET crowbar circuit, which turned out to be a bad idea. Although rated for a continuous \$I_D\$ of 72A (at \$V_{GS}\$ = 10V, though), the transistor got fried at ~500 mA already, despite a solid connection to a large metal beam as heatsink.

Before frying the next components, I'd like to ask:

Is the (a) crowbar circuit applicable in this case?
It does not seem such a good idea to me anymore.
What would be a better power sink circuit?


texts: Force-Sensitive Resistor Break When Pressure is Constantly Applied

texts:
My question is mainly the following:

Is there a force-sensitive resistor that can handle pressure (like 50kg weight) constantly on it? While not having its response curve altered because of this?

Well, the backstory of the problem is that I have been using normal force sensitive resistors like these, and the problem they have is that if you apply the pressure on them constantly, their response curve will flatten out and you will no longer be able to detect minute changes in the pressure. This limitation is also discussed in their datasheet. So my question is: What alternatives do you think I have, to circumvent this issue?

What I am trying to accomplish:

I want to have a force-sensitive resistor, similar to the one I mentioned before. The only problem with the one above, is that if I constantly apply pressure on it (or apply pressure on it over long periods of time), the resistance curve becomes almost a flat line and I will no longer be able to use it. I want something that presents the same behavior as the force sensitive resistor above, however, is more durable when a DC force is constantly being applied on it.