texts: What could cause a quadrature encoder to produce this output?

texts:
I'm working on a software quadrature decoder and testing with a Lego EV3 medium motor (which has an integrated quadrature encoder).

The thing is, while the large motor produces perfectly normal-looking quadrature output, my medium motor produces this:

Channel 2 transitions always lead Channel 1 by 130-200µs.  It is, technically, the right transition sequence for quadrature, but the two signals are almost in phase or antiphase depending on direction.

It's notable that these waveforms are consistent with the ev3dev implementation of the decoder (which I assume is consistent with the Lego implementation) which runs at half resolution by treating edges on one input as clocks and the difference between the two signals as direction.  These waveforms act like they're preparing specifically for that kind of detection (keeping the two edges close maximises the time available to software to sample them correctly).

I had hoped to avoid doing it that way because of the reduced precision.  I want the code to be a generic, full-precision quadrature decoder but also to work with these motors.

The schematics that Lego provide shows what looks to me like a perfectly normal encoder:

Even if the sensors aren't well aligned or if they're slow to transition because the LED is too weak, they still shouldn't produce this output should they?  My reasoning is that if it's an alignment problem then they should show the same phase overlap in both directions -- not a negative one.

I'm wondering if both lines are ramping slowly, internally, but the transition of the schmitt trigger output on one line causes some kind of noise that provokes earlier detection on the other line.

That doesn't sound right.  Does anybody have any better ideas what's going on here?


texts: Interior lighting circuit flashing when connecting inverter driven led stripe

texts:
I am currently doing some work on my car and I've installed a led stripe which is powered by a 12V inverter circuit ( details of that are unknown ). Now when I connect this to the rest of the interior lighting, everything starts to flicker.

The maximum power consumption of the stripe is 60mA, so I don't believe that the power requirements aren't met. I think that the inverter introduces some kind of noise into the supply grid, which causes some spikes.

The interior light cirucit emits a PWM Voltage which varies from 7-12V ( I haven't measured the frequency yet.

My question is, if it is possible to somehow decouple the PWM from the interior light circuit from the inverter power supply, while mentaining the same output. Maybe a voltage follower?


texts: Connecting multiple Net Labels to same Net Wire

texts:
I am using Altium Designer 17. My schematics is Hierarchical and divided into multiple sheets.

Few sheets have microprocessor stuff and other schematics have sensors in it. I have to connect sensor's pins to GPIO pins of the processor.

Sheets in which GPIOs are taken out from schematics symbol of the processor uses conventions like GPIO_PIN_180 as Net Labels and sheets which have sensors uses names corresponding to the functions of that pin as Net Labels (For example, ACC_INT is a interrupt pin of accelerometer).

Now, I want to connect two different net labels but they give me warning/error like Nets with Multiple names. I know how to disable that warning or error but I don't want to disable it as it helped us in the past to find few bugs. I want to know Industry standard to handle such situations to make my schematics readable and acceptable to other experienced designers.


texts:
Schematic created using Multisim

I'm trying to find the equivalent capacitance for the above diagram between nodes b and c but I'm having a lot of trouble understanding which capacitor is in series/parallel to which capacitor.

I know these equations:

Capacitors in series:

Capacitors in parallel:

From looking at the circuit I believe C4 and C3 are in series same as C1 and C2

Would the resulting two equivalent capacitors C4,3 and C1,2  then be parallel with C5 and C6 respectively?


texts:
So I made a small 5v Power Supply (Regulated) using one of Sparkfuns tutorials.

I used a Slightly Different LED (a 2.6v with 20mA) and a 270 ohm resistor ( have no idea why they use a 330 Ohm one...270 was even overkill for mine.

Anyways Im using my Multimeter and measuring the voltages (Marked in purple, - for Ground probe, and + for my + probe).

Im getting a correct 5v reading after the LM7805 (well like 4.95 volts.....close enough), but when I measure after the LED I get 1.8v....

This doesn't make any sense.......

Here are some pictures of the circuit itself, I have drawn arrows to where I measured the 1.8v with my Probe (Positive red probe), the Resistor is a 270ohm, and I was incorrect about the Forward Voltage, it's actually 2.25 (MAX was 2.6......thats what got me confused). Sorry for the Long pictures, but wide-ways they are kinda hard to see. Capacitor values are same as schematic.

edit: Corrected Picture.
edit2: Added picture of circuit


texts:
I would like to implement a boost PFC stage for an alternator that has a large leakage inductance (~40mH). When looking at the schematic, we can see that the boost inductance Lb and the alternator inductance La are connected in series (through the diodes D1 or D2, depending on the half-cycle), and that the large value of La means that it cannot be ignored (and that Lb is useless and can be removed).

In theory we need to measure the instantaneous alternator voltage Va, in order to shape the alternator current Ia waveform the same way (scaled with the error on output voltage Vo). This is clearly impossible as Va and La are intrinsically the same component, so Va+ is not available.
At first I was planning to measure the current and rectified voltage Vr (as should be done in the absence of leakage inductance La), and to compute what Va should look like, knowing the value of La. But then I realized that as soon as I will start switching M1, I will alter Ia and Vr (it is the purpose), so I can't use them anymore.
I have a few ideas in mind about how to workaround this, but they all seem quite impractical (like measuring the derivative of the current Ia when M1 is closed). In addition I was thinking that this problem should be classical, for instance in wind turbines, but I did not manage to find information about this on the web.
Is this a known problem, or is La usually insignificant and ignored? Does a robust solution exist to implement a proper PFC in this situation?


texts: I am designing a 9u rack server with optical ports. I want to implement Thermo Electric Cooler(TEC) for cooling the ICs(switches, FPGAs) on board, so that I can reduce the fan speeds. Is this a good idea, if yes suggest some TEC modules.


texts:
Currently I am working on a project which needs me to configure the hardware from low-speed CAN (100 kbit/s) to high speed (@500 kbit/s).
The CAN controller supports baud rates up to 1 Mbit/s.

I am generating the configuration files using the VECTOR GENy tool. I have tried following configurations, but nothing seems to work out. Did I miss something?

Clock: 60 MHz, sampling 75%, prescaler = 8.

Clock: 60 MHz, Sampling 80%, prescaler = 5.

Clock: 12 MHz, sampling 75%, prescaler = 8.

Clock: 12 MHz, sampling 80%, prescaler = 5.

When I am using the above configurations, I am getting No Ack errors and bit errors. Do I need to modify the RX buffer and TX buffer?


texts: Connecting a kitchen weighing scale to an AC/DC adapter

texts: I have a kitchen weighing scale that uses a lithium 3volts cr2032 coin cell to power it. I also have an AC/DC power adapter that can be set to 3volts output. Would it be safe to connect the weighing scale to the adapter directly? What are the possible implications of this action? I will appreciate your opinions on this.


texts:
I'm trying to write a state machine in VHDL that will scan a 4x4 keypad. I want keyP set to 0 at the start and after a Reset. I also want the Col to be set to "1111" at the start and after a Reset.

As I'm not fully versed in VHDL programming I'm sure it's just a stupid syntax error.
The error I get is:

Error (10818): Can't infer register for "Col[0]" at Lab_7_Keypad.vhd(39) because it does not hold its value outside the clock edge

and the same for Col[1] Col[2] Col[3] and for keyP as well.

Here's my code for the start of it all. Can someone give me an idea where I've gone wrong?

ENTITY Lab_7_Keypad IS
PORT(
nReset          :   IN  STD_LOGIC;
clk             :   IN  STD_LOGIC;
row             :   IN  STD_LOGIC_VECTOR (3 downto 0);
Col             :   OUT STD_LOGIC_VECTOR (3 downto 0);
data            :   OUT STD_LOGIC_VECTOR (3 downto 0);
keyP            :   OUT STD_LOGIC);

END Lab_7_Keypad;

ARCHITECTURE a OF Lab_7_Keypad IS
TYPE STATE_TYPE IS ( Col1Set, Col2Set, Col3Set, Col4Set );
SIGNAL  coltest :   STATE_TYPE;

BEGIN
PROCESS (clk, nReset )
BEGIN
keyP <= '0';
Col <= "1111";
IF nReset = '0' THEN                        --  asynch Reset to zero
    coltest <=  Col1Set;
    Col <="1111";
    keyP <= '0';
ELSIF clk'EVENT AND clk = '1' THEN          --  triggers on PGT

    CASE coltest IS
        WHEN Col1Set =>
        Col <="1110";
            CASE row IS
                WHEN    "1110"=>--row 1
                data <= "0001";
                keyP <= '1';
                WHEN    "1101"=>--row 2
                data <= "0100";
                keyP <= '1';
                WHEN    "1011"=>--row 3
                data <= "0111";
                keyP <= '1';
                WHEN    "0111"=>--row 4
                data <= "1110";
                keyP <= '1';
                WHEN OTHERS => coltest <= Col2Set;
            END CASE;
    --Continues for another couple Case statements for the extra columns


texts: Can I use this analog switch for CAN bus signals?

texts:
In the deutsch 9 pin obd interface for heavy trucks, some manufacturers use the pin F,G for J1939 protocol and some use it for J1708 protocol. I am trying to use a NLAS4684 analog switch with dual SPDT configuration to get the desired output based on the pins usage by manufacturers.

I am worried about connecting an Analog switch next to the vehicle BUS pin. Is it safe to connect this switch to the diagnostic port to route signals? The Rd_on for this switch is low and the current per channel is around 300mA.


texts: Running Treadmill motor without console/controller

texts:
1- How to run this motor with it's controller?
I couldn't find the treadmill console, witch got all the speed, on-off buttons.
The motor runs on 180VDC consuming 5A.

2- Is it OK to run motor on a 230VDC from KBU1010 directly without resisotr?! I don't want to burn the motor trying.
Previously, I've used KBU1010 to run a 220VDC mini lathe motor without problems. But with treadmill motor, I'm not sure how to drop voltage 50V at this power rating.
If my calculations are right, I need a 10K 250W resistor to run the motor without controller. OR, a MC-60 controller, witch both are not options meanwhile.


texts: How to control switch mode power supply feedback voltage through optocoupler?

texts:
The larger design is for a 170 V input, 500 V 2 mA output using a flyback converter. I will refer to the schematic on page 29 of the LT3751 switching controller, also found below.

The feedback pin of the switch controller controls the mode of operation: CHARGE MODE, REGULATION, NO LOAD (Fig 1 page 10 LT3751), also included below. I wish to avoid exceeding 1.34 V on this pin as that pushes it into NO LOAD, and the output voltage can increase up to 10% above nominal (page 14 LT3751).

Using the Isolated 282 V Voltage Regulator on page 29 LT3751, wouldn't this result in the voltage on the LT3751 switching between 0 V and Vcc?

If this is the case, how can I avoid this? I wish to operate in REGULATION mode. Is there a analog optocoupler type device, like a isolated operational amplifier what would pass the voltage sensed between R17 and R18 to the LT3751 FB?

Note the FB pin is internally regulated to 1.22 V (page 8 LT3751), so it would be acceptable to apply a voltage between 1.16 V and 1.22 V when the output is low, and between 1.22 and 1.34 V when the output is high. How could I achieve this using the optocoupler? Also, would the optocoupler present any significant resistance itself into a voltage divider circuit (ON/OFF).


texts:
I'm designing PCB which has pin header connectors(0.1" pitch). So my question is - Is it the standard to put female headers onto PCB and solder male headers to wires or vice versa?

My idea is next:
Female pin headers is better to put on PCB. Why? They are protected with plastic around them, so you can't accidentally short connections and damage PCB(assuming that PCB is more expensive than female headers).

PCB has 34 pins for Arduino and DS3231 module(those pins will be female pins), six pins are signal pins, one is VCC, one GND pin.


texts: How to implement an UART communication protocol

texts:
I have two boards:
Board M: Master board
Board S: Slave board
I am trying to implement an UART communication (data length=8bits) protocol between them. Master board M shall send requests to the slave board S and the latter shall answer.

Example 1:
M board (Tx) --> GET_VALUE --> (Rx) S board
S board (Tx) --> 150 --> (Rx) M board

Example 2:
M board (Tx) --> GET_STATUS --> (Rx) S board
S board (Tx) --> I_AM_READY --> (Rx) M board

Example 3:
M board (Tx) --> GET_STATUS --> (Rx) S board
S board (Tx) --> I_AM_BUSY --> (Rx) M board

I have some questions:
1. Is it a good choice to use a FIFO ring buffer in UART ISR?
2. How to choose the number of Bytes exchanged between the two boards?
3. How to choose the buffer size?
4. Which mode is better for this type of communication? Half duplex or Full duplex ?
5. which type of data should I use ? Should I define some macros like this:

#define GET_VALUE  0x01
#define GET_STATUS 0x02

or I just use this implementation:

#define BUFFER_LENGTH = x;
uint8_t buffer[BUFFER_LENGTH] = "GET_VALUE\n";


texts: Reverse breakdown voltage setting for the diodes in a solar cell model in SPICE

texts:
I want to simulate the reverse breakdown behavior of a two diode model solar cell in SPICE.
The diodes configurations without considering the breakdown voltage are as below:

.model diode d( Is=1.5e-10,  xti=3)
.model diode2 d(Is=1.77e-6, n=2, xti=3)

With the given diodes configurations, I can simulate all characteristics before the breakdown voltage point.

By adding the breakdown voltage point to the diode model, I cannot see the curve in forward bias anymore and it does not work properly.

.model diode d( Is=1.5e-10,  xti=3, vrev=15, BV=15)
.model diode2 d(Is=1.77e-6, n=2, xti=3, vrev=15, BV=15)

In short, when I add the code for reverse breakdown voltage point, my diode does not work properly in forward bias! Please help me with this problem.


texts: Can I replace a lower resolution DAC with a higher resolution DAC with similar characteristics

texts:
My first application requires a 10-bit and a 12-bit Voltage output Quad DAC. I have another application which requires two 12-bit Quad DACs

I have chosen matching DACs MAX5714/MAX5715 which costs 2.85/4.27$ a piece. Here is the data sheet http://www.mouser.com/ds/2/256/MAX5713-MAX5715-472601.pdf. Characteristics of both DAC seem similar

To save some costs, I am thinking of buying just two MAX5715 DAC's instead of three DACs(two MAX5715 DAC + one MAX5714 DAC).

Can I use a higher resolution 12-bit MAX5715 where 10-bit MAX5714 is needed?


texts: auto reset an Arduino using ftdi - DTR signal stays low and needs to go high after 1-50ms

texts:
Hello i have a cheap ftdi that i am going to recreate on a pcb so i can flash my  ATmega2560 chip onboard, the ftdi has a DTR line which is pulled low when the sequence starts but it stays low instead of going low then high after 1ms to 50ms, so i need to find out how i could create a simple circuit which when is pulled low then goes high, how can i do this, i have some simple components to hand.

my stocked parts:

103 ceramic caps

25uF aluminium caps

220uF aluminium caps

some blue ceramic caps labeled "10"

practically all common resistors values

5v zener diodes

5v switching diodes

npn transistors

n channel mosfets

5v reflecting diodes

can i make something using those ? Else I can get what's needed.

Many thank from Edwin

Sorry it's an atmel atMega 2560 chip on a pcb i have the serial lines and reset,5v,ground and two gpios on a pin out.  So I can only flash with a ftdi. And my ftdi DTR line stay low and i need to just pluse the rest line so I need to figure out how to use this low signal to pull the reset low but then high  right after.

IF I was to try this on my arduino Mega or Uno holding down the reset does not work it's a pulse going low then high to load the boot manager. So hence the dfti DTR staying low will not work if directly connected to RST.


texts: Feedback resistors and op-amp instability

texts:
I am a building a circuit which has a differential amplifier part. To keep things simple I have simplified the circuit to only show the relevant part below.

One thing from op amps which is still difficult for me is the selection of the feedback elements, that is, in what range should you choose the resistors. I have seen answers such as: high value resistors will cause issues due to bias current, while low value resistors require higher currents which lead to dissipation, etc.

In the simulation below all the resistors have the same value and are swept from 1k to 100k in steps of 20k. The op-amp becomes unstable as R increases. Even at 10k! You already see some oscillations.

I expect that this is related to the input capacitance of the op-amp. Is this the case? Or are there other factors here? What op-amp parameter should I look for in the datasheet that could give a stable output with high resistance values? And how can one predict based on the input signal what value might lead to instability?

The input of the system: source with 3 µs rise and fall time.

where x = swept from 1k - 100k with 20k steps

with x = 10k


texts: Can an LTE band whether TDD or FDD in a user end (the mobile phone) be used for only one direction, i.e. only to transmit or only to receive?


texts: Material that doesn't let microwaves through, but is transparent to IR

texts: Does a material exist that is transparent to infra-red light, but is opaque to microwaves (S-Band, about 2.5 GHz)? I am basically looking for a filter I can put in front of a infra-red sensor.


texts: Pictures of different adapters, trying to understand how they work (PLC to PC communication)

texts:
I purchased the blue adapter in the picture as a USB/RS232 converter. It takes in the RJ12 cable from my PLC, and converts it to a USB input.

Now when I try to use an RJ12-DB9 Female and then connect that to a DB9-USB which then connects to my computer (via USBO and then try to communicate to my PLC using this method (also seen in the picture), I can't seem to get my program to work. What am I missing here? I'm sure all of my configuration settings are working, so what could be going on here?

Basically the blue adapter works with my program, but the combination of the 2 adapters in the lower part of the picture do not work and I'm wondering why. I understand there are some electronics in the blue adapter (HIN202 for example), but these chips just seem to "assist" in maintaining the RS232 communication process, rather than actually provide infrastructure for it to work.

Edit: Sorry guys....find picture attached and thank you for your comments, hopefully this pic confirms or provides better insight into my situation.


texts:
I bought an air compressor at a yard sale, and the battery was “completely dead” as the previous owner had said. So, I brought it home to try and fix it. I turned it on and the analog meter needle read about halfway. So the battery was not dead. So, I hook up my bench power supply to the charging port, set it to 12v (the voltage printed next to the port), and let it sit overnight.
I woke up the next morning to an unchanged meter needle. I thought maybe something was wrong with the charging circuitry, so I cracked it open, and there was the rather large SLA (Sealed Lead Acid) battery.
I disconnected it from everything and hooked up my multimeter. Instead of seeing the expected 12v, the battery read 8.3v.
I hooked the battery itself up to my bench supply, set it to 12v, and left it overnight again. When I got up the next morning and checked it with my multimeter, the battery read pretty much the same 8.3 volts as before.
Is the battery recoverable? Am I doing something wrong charging it? Or do I just need to buy a new battery?
The battery is a 12v 7Ah SLA battery.
How can I recover this battery, if possible?
I’m not entirely sure of the exact age, but the battery is definitely old. TASK FORCE # 202754 is the compressor.


texts:
I tried to design a PI controller for this zeta converter... but was unsuccessful in doing so.
I wanted to get a constant dc output but got the following waveform.
How to design this PI controller?
Zeta converter is a fourth-order system and his hard to design a controller.
My design of the components are...
L1 = 1.34e-03H, L2 = 1.34e-03H, C1 = 223-06F, C2 = 1.5e-06F, Load resistance = 5.6 ohms, Source volage = 240 V(rms).


texts: How to program an MSP430 chip on a launchboard with no IC holder

texts:
Our university provides MSP-EXP430FR4133 LaunchPad Development Kits like the one shown in this picture :

Although this doesn't have a slot to program an IC like these ones do:

I was wondering if it's possible to program an IC such as the MSP430G2231IPW14 using the development kits of our university? And if so how would I go about doing this?


texts: Origin pole in type II compensator using OpAmp

texts:
I am reading about Type II Compensator Using Op-Amp from the application report here (page 4).

From the transfer function (4), we can see that there is an origin pole, \$f_{p0}\$. However, the formula (8) implies that \$f_{p0}\$ is created by R1 and C1 not origin pole.

Is this a mistake?


texts: What does ground mean/do when calculating eq. reistance?

texts:
For the given circuit, I was asked to calculate the eqv. resistance:

But, I'm not sure what does grounding some of the resistors do?
In which way does it change the calculation or is there no difference whatsoever for the given?

(there is no need to solve the question, just an explanation would suffice, thanks i advance)


texts: What is the formula used for servo motor positioning?

texts:
First of all, to be clear, I am not very experienced with mathematics applied to electronics but I have had the interest for a while.
What is the right approach to knowing the position of a servo motor so you can display it in your computer? I know encoders are used, but I'm interested in the math happening behind all of this.
What sparkled my curiosity is that I work with a motion control robot that has a motor to control a camera lens. You can calibrate a lens by inputing the lens' physical distance to an object and assigning that number (for example, 7") to a motor position.
This motor is a servo.
The process is fairly simple, by zeroing the motor at the lens' "infinity", once you physically move the lens (the motor has a gear that aligns with the lens' teeth, thus moving along with it) you can stop at any spot (7" like stated before) and store the motor position to that.
By doing a zero position, middle point and close focus point, you essentially have the lens figured out for the system to travel end to end and be quite precise about the lens' current physical position (for example, you stop at 12" and it will be showing that in the computer)
What is the math behind this? How do you approach this challenge correctly?


texts: High Voltage Series Pass Transistor - Low Voltage Control

texts:
I am having some difficulties getting my output stage to work correctly. Here is some info:

I have a +48VDC source with a series pass transistor to drive a load between +45V and 0V. The control system uses op amps and can have an output voltage of anything I wish really. (+5/-5, +5/GND, +12/-12, +12/GND). Its going to depend on my output stage.

Devices I tried:
D44VH10 (Vce=80V,  Vbe=7V, Ic=15A)
TIP142  (Vce=100V, Vbe=5V, Ic=10A)
2N6039  (Vce=80V,  Vbe=5V, Ic=4A)

What I am having problems with is actually getting my output stage to go from +45V to 0V.

I have tried a few combinations of NPN pass transistors controlled by a PNP in a darlington type setup and this meets all my requirements. However it requires my op amps to run at +48V which they will happily do while on fire. If I lower my op amp's output swing to +12/GND then the load only gets around 26V maximum.

I then tried a PNP pass transistor with an NPN control in a similar darlington setup all controlled by an NPN to ground. This worked and allowed my to use +5/GND as my output swing but even if I applied 48V and 1A to my control NPN my load never received more than 22V.

I then tried the same as above but with a MOSFET to ground and I got a 27V at my load. I modified again an used the MOSFET to drive a photo transistor which in turn drove an NPN series pass transistor from the 48V source. I managed to get my 45V out to the load this way but the temperature variations and unreliability of the photo transistor package does not meet my requirements and worst of all OFF was a state passing around 7mV and 2mA.

================================================================================

So, I am missing something here. What is the correct way to drive an output stage from a lower voltage control system?

The whole reason I am doing this is because the only op amp that can 40V+ available to me cost $13/piece. If I can get my control circuity to a lesser value I can get them for $1.


texts: Equations for a simplified transistor circuit

texts:
In the following circuit:

I would like to greatly, greatly simplify how the components work just to be able to make a dumbed-down version of the equations. Let's assume the forward-voltage of the LED is 2V (and it doesn't have any other properties), and the forward voltage of the NPN transistor to be 0.7V (and simplify it so it acts like an on/off switch).

What would be the system of equations to solve for the current/voltage through the components when:

The switch is turned on?
The switch is turned off?


texts: OLED SS1306 displays on one side only when using AVR

texts:
I have an I2C 128x64 OLED display here. I've tried using Arduino and everything works flawlessly. Now I'm trying this but just writing in straight-up C code. Majority of the display is garbled up.

I've seen a post somewhere with a near similar situation but that is for 128x32 and the garbled up portion is horizontally aligned. The post wasn't helpful anyway so I'm posting here.

I'm using the library from this repository. https://github.com/Sylaina/oled-display

I believe it is an issue with my initialization sequence. I've extracted it out from lcd.c here.

const uint8_t init_sequence [] PROGMEM = {    // Initialization Sequence
    LCD_DISP_OFF,    // Display OFF (sleep mode)
    0x20, 0b00,        // Set Memory Addressing Mode
    // 00=Horizontal Addressing Mode; 01=Vertical Addressing Mode;
    // 10=Page Addressing Mode (RESET); 11=Invalid
    0xB0,            // Set Page Start Address for Page Addressing Mode, 0-7
    0xC8,            // Set COM Output Scan Direction
    0x00,            // --set low column address
    0x10,            // --set high column address
    0x40,            // --set start line address
    0x81, 0x3F,        // Set contrast control register
    0xA1,            // Set Segment Re-map. A0=address mapped; A1=address 127 mapped.
    0xA6,            // Set display mode. A6=Normal; A7=Inverse
    0xA8, 0x3F,        // Set multiplex ratio(1 to 64)
    0xA4,            // Output RAM to Display
    // 0xA4=Output follows RAM content; 0xA5,Output ignores RAM content
    0xD3, 0x00,        // Set display offset. 00 = no offset
    0xD5,            // --set display clock divide ratio/oscillator frequency
    0xF0,            // --set divide ratio
    0xD9, 0x22,        // Set pre-charge period
    0xDA, 0x12,        // Set com pins hardware configuration
    0xDB,            // --set vcomh
    0x20,            // 0x20,0.77xVcc
    0x8D, 0x14,        // Set DC-DC enable
};


texts: Powering LED Strips greater than 5 Meters long?

texts: Manufacture stated to run 12v 5 amp per 5m led.  Im going to be running 7.5 meter, which is using 1 set plus half another.  From research its suggested to go to 24volt power supply.  Question 1 is can I connect the 2.5 m strip to end of the 5m without any real issue and push current that far or do I need to wire the 2nd strip back to the power supply?  This is going down a 24 foot walk in closest so dont really want to run 2nd set of wires back.  From my calculations a 24v 7.5a should supply this 5630 dual row led 120 led p meter.  Is there any flaws in the above logic, or can I safely run a higher v power supply.  I want to be able to leave these one all time if I chose to.


texts: resistors misconception - is current-limiting effect circuit-wide?

texts:
Resistors are used to drop current Amp and Voltage, following Ohm's law.

I can't understand some of their applications: we use them cause we sometimes want to drop the voltage a little in a specific point of the circuit, but from what I understood the intensity drop they produce is system-wide.

So, in a circuit like this,

simulate this circuit – Schematic created using CircuitLab

the V5 emf provides X Amp of current to the diode (D1) and R1 provides a certain Voltage drop.

If I rearrange the diode to look like this, does the same current X flow through the diode D1? (therefore it is not able to draw all the current (charge) from the source?)

simulate this circuit


texts:
The circuit consists of following:

simulate this circuit – Schematic created using CircuitLab

And video on this link.

Summary: When there is no current flow on the circuit, supply voltage is about 16 volts, and the voltage difference between V_SUPPLY and VD is 0 volts. However, the voltage on the drain of constant current LED driver is 13 Volts. How could this be? Does the multimeter itself messes the results? And how does LEDs behave in this condition - when led driver is turned off?


texts: How come Misra C checker is such a prestigious tool?

texts: Professional compilers such as IAR Embedded Workbench offer Misra C checkers only in their premium versions. Isn't Misra C checker a style checker on elements like indentation, variable names? Why does it seem to be so highly sought after?


texts: In a line-level audio signal, what function of voltage produces amplitude?

texts:
When I record audio from the line-in jack on my laptop, what function of voltage produces recorded amplitude?

followup/example:

Since I've been told "voltage", unqualified: I apply a voltage square wave to a mono cable. (tip-sleeve switches between 0V and +5V every second). Since the voltage as a function of time is a square wave, why is the waveform of the recorded audio not a square wave?

And here's a recording of the same signal at 40Hz:


texts: Confusion about which time interval to choose to measure the firing angle

texts:
The firing angle, as I understand, is defined as $$\alpha=t \times \frac{360}{T},$$
where \$t\$ is the time interval between the beginning of the applied voltage and the beginning of the voltage waveform on the load.

I tried to simulate the motor speed controller below.
And the scope shows (Green=input, Red=load)

Which time interval do we have to use in this instance to measure the firing angle? It is somehow confusing because the source voltage and the load voltage start at the time, and there are three time intervals to consider.


texts:
This is a novice question.

There is an accelerometer which outputs -10 to +10V voltage output.
If I sample the output for constant output(accelerometer is not moving), can I say anything about signal to noise ratio by looking at samples? What should be the method to investigate SNR here or impossible?


texts: PWM for three phase induction motor control

texts:
I have been implementing control software which shall control the three phase voltage source inverter for controlling the induction motor. There are two requirements as far as the pulse width modulation (PWM):

carrier frequency shall be variable (due to acustic noise reduction)
the current control loop shall be calculated eight times per PWM period (due to minimazing transport delay  - according to the Digital Control in Power Electronics section 2.2.4, which is free available for download)

The first requirement means that the period of the pwm triangular carrier is not fixed. To be able to fullfil the second requirement I need to start A/D conversion eight times per PWM period. I am going to calculate the current control loop in the "end of A/D conversion" interrupt service routine. So I will be facing a problem that the associated interrupt service routine will not have got fixed execution period (due to the variable carrier period), which is of course problematic as far as integral time contstant of the PI controller.

Is there any other solution then interrupt service routine with variable execution period? Thanks in advance for any ideas.


texts: USB-C charging cable for Nintendo Switch

texts: I am trying to change a broken USB-c charger connector for a nintendo switch by changing the male end connector.  The charger cable has 5 wires 2 red(Vbus) 2 Black (GND) and a small white cable that was connected to the PCB board labeled B-side.  I have the images attached the Vbus and GND are basic, however I am not sure what the white cable is for and how to find a correct replacement connector to refurbish this adapter.  Any help would be appreciated. you can see in the picture where that wire was attached


texts: Transimpedance amplifier with decompensated op amp

texts:
I am trying to tune a wideband transimpedance amplifier for maximum speed. I am experimenting with the OPA846 and OPA847 op amps which have large GBW but they are not unity gain stable with minimum noise gains of 7 and 12 respectively.

The minimum noise gain limits how much bandwidth I can get from the op amp with a typical transimpedance topology, and I am thinking about operating below the minimum noise gain with the following circuit:

simulate this circuit – Schematic created using CircuitLab

The current source with shunt resistance (~1Gohm) and capacitance (<1pF) is an APD in my case. The APD is one of the reasons I am able to explore such high frequency operation because it has very small shunt capacitance at <1pF.

Ignoring Rin, the noise gain has a zero at 1/(RF * CD) and a pole at 1/(RF * CF). The noise gain at high frequency is 1 + CD/CF and it needs to be greater than the op amp's minimum noise gain for stability.This is shown by the "Typical transimpedance application" curve in the bode plot below.

What are the pros/cons of adding a pole with RIN at 1/(RIN * CD) after the feedback pole 1/(RF * CF) and having a high frequency noise gain less than the recommended minimum? The idea is that the second pole in the noise gain would add stability when operating below the minimum noise gain where the op amp's open loop gain has a second pole. This is shown in the second noise gain curve in the bode plot.

The only problems I can see is that there would be some current division between RIN and RS, but it would be very small since RS is very large. Also, RIN would add Johnson noise.

Has anyone seen this anywhere or done this before?

Thanks


texts:
I am attempting to make a Stereo Power Amplifier using two TDA2030A amplifiers.

I want an output of at least 25 watts per channel. The datasheet shows me that I need to add a pair of power transistors, BD907 and BD908 if I want my amplifier for higher power output. There are two circuits shown below and the one with the power transistors outputs more power. My question is this. Can I replace these BD907/908 with TIP35C and 36C , which are more easily available?

I have purchased a transformer of 24V-0-24V, 80VA.

BD907 datasheet http://pdf1.alldatasheet.com/datasheet-pdf/view/2587/MOSPEC/BD907.html

TIP35C datasheet http://www.onsemi.com/pub_link/Collateral/TIP35A-D.PDF


texts: No silkscreen on board? How common is that? What are the advantages?

texts:
I'm a young engineer and I just started at my second job.  I was surprised to see that the PCBs have no silkscreen.  I'm currently working on the redesign of a PCB currently on the field and I'm trying to push for the re-introduction of silkscreen on boards.  Some of the responses I get are:

boards are cheaper without silkscreen
since there are so many 0402 components, the silkscreen won't be readable anyways
there are too many vias and placing of silkscreen would be very difficult
you can view where the components are on your PC

In my opinion, those are not valid responses, but I'd like to know if there are any other companies out there that have similar "practice".  Some of the products we produce go from 1000/year to 20K per year.  But no silkscreen makes it more difficult to debug/test prototypes and field returns.


texts: Can multi-project wafer service merge projects with different number of layers?

texts:
I would like to ask some help to better understand limitations of multi-project wafer services (MPW).

In nutshell, i found about the service, that it merges many projects on wafer, so one project only have to pay for a share of its surface. While it is easy to understand, that i pay only for 100 mm2 of an area of 70000 mm2 so it costs less, i nowhere found to mention, that asic projects may have different amount of layers for their design. Number of layers could be anywhere from 6 to 35 and even more. If i need for example 30 layers for my design, and there are only projects with demand of 15..20 layers, how an MPW service can merge my project with cost effectivity? Can it do that at all?

I dont know, if my question involves any industrial secret or not, tell me if i was that careless.

I will be happy with any reference to internet blogs, e-docs, books or anything about the question.


texts:
I have designed an land pattern for a micro USB connector. The connector have 2 x 0.9mm drill holes under it.

The problem is the clearance distance around these holes being to big and overlaps the soldering pads for the very same connector.

These holes are just plain holes, I don't need the same clearance rules as for traces. Is there a way to override the automatic clearance and set them manually?

---- EDIT ---

As you can see, the hole clearance overlaps the pad on the top layer (red).


texts:
I was in computer organization lecture and when we wrote what the CPU does during an add instruction (like micro instructions) something got me thinking.

I didn't understand how we let one of the FFs output to the internal bus and tell other FF to latch the data in. If we send the control signals at the same cycle how is the latter one latches the data in at the same time? Isn't it violating the setup and hold time?


texts:
Here is the circuit

I know that Vc(t)=Vs(1-e^(-t/RC)) but I'm not sure if Vs in this case refers to the 50V or the voltage across the capacitor.  If it is the voltage across the capacitor how would I solve it?  What would be the resistance of the capacitor?  I was told that capacitors act as short circuit initially so would I assume it's resistance is 0?  I couldn't find anything that showed how to solve RC circuits this complex, they were always just a single resistor and capacitor.

Any help is appreciated.


texts: Laptop battery not working after replacing cells

texts:
I have a Sony VGP-BPS21A battery that I use to power my laptop. It is really old, like 5-6 years now and its cells have lost more than 50% of their capacity. As a new OEM is very expensive, hard to find and probably not recently manufactured, I decided to keep my battery controller and replace its 18650 cells.

So everything went fairly well, except I have broken the temperature sensor (a thermistor). Anyway, I have succeeded in fixing it and now my laptop powers on. However, it refuses to charge the battery.

I have checked some parameters my OS retrieves from the battery, and apparently it shows a capacity of 0.0Wh (previously 52.4Wh). I suspect important data was erased from the controller when I disconnected the old cells. I have googled some solutions to reprogram the controller, but only commercial solutions were found. Is there an easy solution to get the controller to charge the battery cells?

I have attached photos of the controller PCB.

IC1 is the MCU (R2J240 reference).


texts:
I'm interested in building a circuit to switch between 2 sim cards, and found a design guide by GSM module manufacturer Telit. (New design guide link here, see pg. 16+)

In particular, "Figure 6" of this guide shows the use of a p-channel MOSFET to switch the SIM Vcc on and off, and there's a separate multiplexer for the data, clock, and reset lines.

I was wondering what the alternative ways of doing this were, and what affect they might have.

For example, would it be possible to remove the multiplexer and simply control the SIMs using the MOSFET, or would it be possible to use a switch on only the data line, and share the power, clock and reset between the SIM cards?

I know the voltage on SIM cards can be either 1.8V or 3V, so maybe sharing the Vcc line would cause issues?


texts: What is the difference between these two ICs?

texts:
Is there a difference between these two ICs, or are they the same?

https://assets.nexperia.com/documents/data-sheet/74HC4049.pdf

http://www.ti.com/lit/ds/symlink/cd74hc4049.pdf


texts: What kind of sensor could be used to detect shadow shapes?

texts:
What kind of sensor could you use to detect the shape of a shadow falling on something, say the shadow of a hand on a wall?

I first thought of an array of LDRs but the resolution would be quite low, and you would need quite a lot of them. Or is this feasible?

Then I thought of a camera with image recognition software, but the problem is that the object causing the shadow would get in the way of the camera's view. Unless maybe the camera was at an extreme angle.

Is there any obvious solution for this?

EDIT: Sorry, yes it is not necessarily an analog sensor so I have adjusted the title. The application is to use different shadow shapes to control a robot, as an interface.


texts: Thermal time constant, thermal resistance, thermal capacitance

texts:
Where does the thermal time constant, thermal resistance and thermal capacitance in IEC standard 60853-2 come from (e.g. section 4.1.4)?

They are used to determine the partial transient of a cable.

I understand that the thermal time constant may be provided by the cable producer. It can also be estimated. Where is this estimation described? Is it in some IEC standard? Thanks.


texts: what determines the lower limit on the number of turns in a secondary coil in a step down transformer?

texts:
I am interested in understanding what factors govern the lower limit on the number of turns in the Secondary coil of a step down transformer. I have read that a Primary coil with too few turns will induce a very weak magnetic field in the core, but what happens if the secondary coil has a very low number of turns?

If the secondary coil uses a shorter wire, the resistance is lower and so voltage induced in the secondary coil produces a greater current, as per Ohm’s law. This greater current may be higher than the wire's maximum current capacity and cause dangerous or undesirable levels of heat in the wire, but is this the only factor governing the minimum number of turns in the secondary coil? If the secondary coil has too few turns, can the efficiency of the transformer be reduced in some other way?

If I want to have a step down transformer with as few turns as possible in the secondary coil, what problems do I need to be aware of, and how can I calculate what the minimum number of turns in the secondary coil could be?


texts:
I am converting arduino-nrf905 library for stm8s. There is one spi function on the arduino library, it is SPI.Transfer(uint8_t reg). This function can write and read spi. But, there is two function on the stm8s peripharel library. This functions are SPI_SendData(uint8_t reg) and SPI_ReceiveData(void).

SPI.transfer code of arduino library:

byte SPIClass::transfer(byte _data) {
  SPDR = _data;
  while (!(SPSR & _BV(SPIF)))
    ;
  return SPDR;
}

SPI_SendData of STM8S library:

void SPI_SendData(uint8_t Data)
{
  SPI->DR = Data; /* Write in the DR register the data to be sent*/
}

SPI_ReceiveData of stm8s

uint8_t SPI_ReceiveData(void)
{
  return ((uint8_t)SPI->DR); /* Return the data in the DR register*/
}

I want to convert this code to stm8s, but it does not work.

Arduino Code:

((uint8_t*)data)[i] = spi_transfer(NRF905_CMD_NOP);

STM8S Code:

SPI_SendData(NRF905_CMD_NOP);
((uint8_t*)data)[i] = SPI_ReceiveData();

Thank you!


texts: Is there are better component to use rather than multiple diodes?

texts:
I am a long time computer programmer, but am fairly new at creating my own circuits.  The project I am working on currently is functioning properly, but I thought there may be a more elegant solution.
I am working on a circuit that will allow me to attach a NES Controller to the joystick port of an Atari or Commodore 64 without having to modify the NES Controller.  I do this by reading the NES controller with an Arduino and then "activating" the correct switches on the joystick port.
The Arduino pins are set as low input pins until they need to be activated.  When activated, they are set as output.  The pins are kept low all the time because if they are set high, they could damage the CIA chips in the Commodore.  To make sure that voltage is never applied to the CIA chip, I have placed 6 diodes in the circuit in the event that a pin is accidentally set high, it won't kill the CIA.  Five of those pins are for the controls (Up, Down, Left, Right, and Fire).  I am also pulling +5v from the Commodore port to power the Arduino through the RAW pin.  However, the RAW pin also gives +5v if the Arduino is powered through USB.  So, a sixth diode is used to keep that voltage from going back to the Commodore if the USB is connected.
Currently, I am using 1N4001 diodes.  My question is if there is something better / cheaper / easier to use than those diodes for this purpose?  Are these diodes too big for this circuit?  If so, what would be a better alternative?
Here is the schematic:


texts:
First of all I know there are many similar questions answered but I'm still a bit unsure on why my current set up doesn't work. I'm really outside my area of expertise so be kind.

This is what I have:

A door strike from Assa. See datasheet:

6 wire cable connected to door strike. I don't want to to dismantle the door to see how it's really connected so I'm assuming red / black is positive and blue / white is negative. Does that seem correct?
Arduino that controls a relay. This part works.
DC Power adapter - 12V 1A

So I have connected the positive wire from the power adapter to the com port on the relay. Then I have twisted together the red and black wires from the strike and connected it to the NC port on the relay.

Then I have connected the negative wire to the blue and white wires.

But when the relay switches on nothing happens. What have I done wrong? What should I do to trouble shoot it. Should I add a diode like in datasheet?


texts: How to work out if a diode's reverse recovery time is good enough?

texts:
I'm designing a circuit using high frequency PWM signals and I was told to consider the reverse recovery time of the diodes I'm using

Would I be correct in assuming, from my understanding of reverse recovery time that:
If I have a PWM signal coming in at for example 20kHz like in the circuit below, then that means the voltage across the resistor will change every 50uS *

*(As: T = 1/F = 1/20k = 50uS)

So the required diode reverse recovery time would 50us or less

Is this a correct assumption?

simulate this circuit – Schematic created using CircuitLab


texts: Can available -ve supply somehow used for an IC requires positive voltages?

texts:
This is a doubt related to a charge sensitive amplifier. Amplifier specification says: Power consumption approx. 80 mA at -20V at 60Ω. Does it mean that the amplifier operates in -20v / GND supply ?. The amplifier has two ICs CA3046 (NPN Transistor array). I have attached their ratings and a link to Data sheet. They need positive voltages in all scenarios. Does a -20v/GND supply provide these +ve voltages?
The link is :Link to data sheet

Unfortunately, I don't have the schematic of the amplifier. I attached the manual of the amplifier as well.


texts: Inductive and Capacitive couplers in power line carrier communication?

texts: I have searched a lot in internet for getting simple circuit diagrams of Power line couplers (both inductive and capacitive) which I am supposed to explain to my students. Also our college library doesn't have books on the subject of power line communication. So I would be grateful if someone can help me with the circuit diagrams and working principle of inductive and capacitive couplers which couple information to and from power line cables. Or at least please mention any good website links or other internet resources.


texts:
I have redesigned one of my boards to the ICM-20689 (datasheet) instead of the ICM-20789 because of a voltage issue that I previously had. Link to previous issue.

A little background on my setup. The ICM-20689 is running on 3.3V with 3.3V on the VDDIO pin and 10k pullup resistors on the I2C bus. The master device is running at 5V, but only needs 60% (3V) to read a voltage high. The frequency is set to 400kHz.

I have been able to communicate with the device just fine and get good data. I wanted to look at the bus voltages with an oscilloscope to make sure that everything looked fine, and I noticed something a little odd. Before the master starts talking with the ICM-20689, the bus line is at a voltage of 3.3V. When the master wakes up the device and starts receiving data, the voltage jumps to 3.7V.

My oscilloscope is not the greatest, but the probe is in 10x mode, and I am using the trigger to capture the data on the first packet of data sent. On all subsequent data packages, the voltage stays at 3.7V. Is this is an issue with the device, or is this maybe an issue with my measurement setup?

Edit: Here is the schematic for the ICM-20689. This "voltage bump" happens on both the SCL and SDA lines. To my knowledge, there are no internal pull-ups active on any devices on the bus.

Is this normal for I2C? What is causing this bump? Is this something I should be worried about, or is this within allowable tolerances?


texts: graph of transfer function for RC filter

texts:
In an answer to this question Leon Heller links to a tutorial which includes the following graph:

I'm a bit confused. Shouldn't the graph for an RC filter monotonously decrease, without the inflection point?


texts:
My attempt at building a crystal set has resulted in failure. The circuit I used is the simplest one I could find:

I tried without a ground and with the ground from the power outlet (I heard that this was dangerous, but it's the next best thing I have to a rod in the ground). The result was the same for both. I transmitted from my radio at around 145 MHz. The moment I keyed, I could hear a small click on the earpiece, but nothing more. I couldn't hear myself when I spoke into the microphone.

Here's a picture of the actual circuit:

I believe the diode is a 1N34A.

My guesses at the problem were impedance mismatch and the lack of a good ground, but I also remember that the only issue that would cause is a weaker signal, and I'm right next to the transmitting station, so I'm not sure if that's the reason I can't hear anything. It's really discouraging to spend money on something that doesn't work, so before I go out to get a grounding rod and a sledgehammer or a huge length of wire for an antenna, are those likely to be the reasons I'm not getting any sound? What else could the problem be?


texts: Computing the maximum power that this opamp provides to the load Rl without occurring distortion

texts:
Here's the schematic:

So first stage is a differential amplifier where vo1 =3.72V in DC (Vin= 0). In this stage i can say AmplVo1 = gainStage1 * AmplVi where distortion only happens when vo1 is bigger than Vcc (Vcc = 8V) or when T6 hits saturation.

The first case is when Vcc - VoDc = 8-3.72 =4.28 V , this is a critical point. I can imagine a sine wave with a DC component of 3.72 where its amplitude doesn't surpass 4.28 V (limit).

With T6 i dont really think it is necessary do show work because it wont affect anything, the amplitude of v01 will be bigger than the computed above.

My problem is what i should do with the next 2 stages. I remember my teacher saying to compute the DC voltage from the emissor T2 and subtract that from the DC voltage of Vo1 but i'm not sure what to do with that.


texts: Can I use constant current LED driver as input to Buck regulator?

texts:
I have an 100W constant current LED driver that I bought in error but maybe I can use it in another way. I want to use 3 buck regulators to pwm control each individual color of 90W RGB LED. Can I input constant current supply to a buck regulator (will use 30W max per channel)?

Constant current driver is rated as 8~12V while buck regulator is rated at 9-48V, will this cause any issues especially when PWM is used?


texts: What happens if I use the 110v (US) electric toothbrush charger on 220v (South East Asia)

texts: I accidentally charged one cycle and the toothbrush still works. But is it safe to use it in this voltage? What's the effect on the battery? Does it charge in half voltage or is there any in built voltage regulation?


texts: Why EP0 is disabled on USB_RESET in Atmega32u4?

texts:
I use atmega32u4 (arduino pro micro), powered from usb.
In atmega32u4 datasheet p. 267 it is stated:

When an USB reset is detected on the USB line (SE0 state with a minimum duration of 2.5μs), the next operations are performed by the controller:
• all the endpoints are disabled
• the default control endpoint remains configured

However, this example demonstrates that control endpoint is disabled. What is the reason of it?
#include <avr/io.h>

void main(void)
{
  UHWCON |= 1 << UVREGE; /* enable internal USB pads regulator */

  /* start pll */
  PLLCSR |= 1 << PINDIV;
  PLLCSR |= 1 << PLLE;
  while (!(PLLCSR & (1<<PLOCK))) ;

  /* start usb controller */
  USBCON |= 1 << USBE;
  USBCON &= ~(1 << FRZCLK);

  /* configure control endpoint */
  UENUM = 0;
  UECONX |= 1 << EPEN;
  UECFG0X = (0 << 6) | 0; /* control type, out direction */
  UECFG1X |= (2 << 4) | (0 << 2); /* size 32, one bank */
  UECFG1X |= 1 << ALLOC;

  USBCON |= 1 << OTGPADE; /* enable VBUS pad */
  while (!(USBSTA & (1 << VBUS))) ; /* wait until VBUS line detects power from host */
  UDCON &= ~(1 << DETACH); /* pull up D+ (attach) */

  while(1) {
    if (!(UECFG1X & (1 << ALLOC))) {
      DDRB |= 1 << PB0;
      PORTB |= 1 << PB0;
    }
  }
}

Build with:
avr-gcc -c -pipe -gdwarf-2 -g2 -mmcu=atmega32u4 -fshort-enums -fno-inline-small-functions -fpack-struct -Wall -fno-strict-aliasing -funsigned-char -funsigned-bitfields -ffunction-sections -I. -DF_CPU=16000000UL -mrelax -fno-jump-tables -x c -Os -std=gnu99 -Wstrict-prototypes test.c -o test.o
avr-gcc test.o -o test.elf -lm -Wl,-Map=test.map,--cref -Wl,--gc-sections -Wl,--relax -mmcu=atmega32u4
avr-objcopy -O ihex -R .eeprom -R .fuse -R .lock -R .signature test.elf test.hex


texts: How to select BLDC motor for high torque applications

texts: For electric vehicle I need to choose BLDC motor. Rated power around 2 to 3kW 48 nominal voltage. I don't need high speed, but would like to have high torque at low rotation speeds. There will be reducing gearbox installed on top of motor 1:10. On what parameters to look when choosing motor? For example, is motor with lower RPM per V "slower" and thus more powerful, or does it means just its efficiency is worse?


texts:
I wonder if someone can help me. How will one go about to create a simple circuit simulator? Similar to Multisim, just a lot simpler!

Basically, I only need resistors, capacitors, inductors and voltage sources.

Is there a tutorial I can follow, to create this using C# and Visual Studio?


texts: STM32F105 - USB OTG - BusFault at 0x1fff7a10

texts:
I try to implement a VCP on a STM32F105RB with the STM32_USB-Host-Device_Lib_V2.2.0

I was able to compile the Code sucessfully.

My Hardwareconfiguration is the following:

Mini USB directly (without series resistors) to D+ and D- of the STM32. +3.3V to PA9 (for BusSensing)

After debugging start in atollic, the host detects a new device but it is not listed in the device manager.

After few seconds, i get a BusFault on the STM. The BFARVALID is set and the BFAR is 0x1FFF 7A10

This is interessting, since the Addressspace between 0x0804 0000 - 0x1FFF AFFF is reserved.

If i restart the firmware 2-3 times (NOT the debugging process, only do a soft reset not a hard reset) and click run again, then it detects the VCP correctly after some tries. It shows a not working COM9 and a working COM10 in the device manager. And it does not end up in the bus fault anymore.

Can anybody help me solve this problem?

Thanks

Attached are the Registers at BusFault and the Dissassembly.

Memory MAP

Registers at BusFault

Dissasembly of the RAM Address

Dissassembly of the SP Address

CFSR Register at BusFault

MMFAR Register at BusFault

Update:

Layout: Layout of the Breakoutboard

Schematic: Schematic

Documentation: Link

For VBUS-Sensing, i have connected PA9 with +3.3V. My board is powered through USB. So as soon as i plug in the USB-Cable, the board get its power and as soon as 3.3V is up, VBUS-Sense (PA9) is also high.


texts:
I have a Tektronix DPO2014 and I'm trying to get a feel for what I can expect in terms of precision and accuracy performance on a clean and stable voltage. I'd like to be able to accurately and precision measure voltages in the 0 - 20mV range with a precision of 1 mV, just to throw in use some concrete numbers.

So I hooked up five fresh AA batteries, connected the GND clip of the channel 1 probe to the ground of the battery pack, and connected the witch's hat clip of channel 1 to the positive terminal of the battery pack. I set up the scope to display Measured values of Min, Max, and Mean and what it tells me is: Min = 7.96V, Max = 8.2V Mean = 8.09V - 8.11V (watching it over time).

I presumed a battery pack would be a very clean and very resilient (to noise) DC source. So how might I figure out what this apparent +100mV / -140mV of noise riding on my measurement is coming from? Even if I turn on Averaging (8 samples) in the Acquire menu, I see a span of 8.072V - 8.124V for the min / max span, and the mean becomes 8.109V to 8.112V (so more like 25-30mV of deviation from the mean).

If I switch channel 1 to AC coupled mode and use 64 sample averaging on Acquire, I see min/max values of about -1.8mV to +7.2mV. Can anyone think of what, if anything, I might be doing wrong? Or is the performance of my oscilloscope just not capable of accurately and precision measuring signals in the sub 10mV range?


texts: My IR receiver becomes erratic after one motor in the circuit starts spinning

texts:
I am trying to make a remote control car using an Arduino Uno and IR receiver modal VS1838B. The system worked as planned except that IR receiver gets erratic after any one motor spins.

upon starting up, all functionalities works as planned
after 1 motor spins , the IR receiver will barely receive.The light on the receiver will stop blinking until the motor stops.
If I disconnect the motors, the IR receiver will receive normally.

I suspect that there is a current affecting it after the motor starts spinning

I've included my circuit diagram below.

Pin 11 connects to IR receiver
Pin 5 activates the transistor for the left wheel
Pin 6 activates the transistor for the right wheel
The power source for the IR receiver is different from the motor
All the ground actually connects back to the UNO ground. Simplified it below.

EDIT:

So I did an experiment to isolate and check if it was the motor/EMI that might be causing the IR receiver not to receive properly. I changed one motor with a light bulb and tested if activating the light bulb will affect the receiver. The result was that activating the light bulb did not affect it while activating the remaining motor affected it. Hence I am quite sure that the motor/EMI is causing the receiver to be erratic.
I am not sure how to place the ceramic capacitor, so I drew a diagram of what I think it could be. Is this correct?


texts: How determine the number of LEDs that I need?

texts:
So I am trying to do some calculations for a UV curing system that the place I am interning for is working on. One of the tasks that I am assigned to is to determine how many LED does the system need given the energy needed to cure 1 cm square of UV ink. So I have done some research on my own and find some formulae online but I am still not quite sure which unit I should depend on to determine the amount of LED that the system need. So far I have found a formula that gives me W/m2 and one that uses Lm (Lumen).
Thanks in advance guys.


texts: IR LED - Help me convert 'Maximum radiant power' to irradiance (Watts per meter squared)

texts:
I am not an electrical engineer or physicist. I am trying to understand if the light emitted by an LED poses an eye hazard.

A manufacturer has a device that has LEDs in it. They are infrared LEDs. They emit light at 950 nm and their 'maximum radiant power' is listed as 3000 mW/steradian. It is my understanding that W/steradian is called 'radiant intensity' by physicists.

To determine if the LED is a hazard, I need to calculate its irradiance, E, (Watts per meter squared). This is the equation I wish to use: E (W/m^2) = Sigma(from 770 nm to 3000 nm) E_lambda x delta_lambda. E_lambda is the spectral irradiance (W m^-2 nm^-1) and delta_lambda is source spectral bandwidth in nanometers (nm).

I cannot figure out how to use the given information (950 nm, 3 W/sr) to calculate the spectral irradiance or the source spectral bandwidth. Can someone help?

Thanks!

(Note added January 16, 2016) It took awhile but I think I found the datasheet for the LED. I know I wrote 3000 mW/sr in my original post, but when I spoke with the manufacturer I discovered that the LED in question is actually only 1000 mW/sr.

Here is a link:

http://www.vishay.com/docs/81009/tsal6100.pdf

Thanks!


texts: How to tristate output digital pin on a pic 16 series microcontroller?

texts:
I know that I can set digital output pins as high and low like this in c:

OUTPUT_PIN = 1;
OUTPUT_PIN = 0;

Is there any way to set that said pin as tristate or high impedance output, as some external chips (I'll be using sram chip) require tristated/high impedance inputs to them?

I'm using xc8 c compiler.


texts: Confused about the meaning of hardware specification

texts:
This question is not directly about design but meaning of a concept used in electronics design.
Basically, I cannot find the clear explanation regarding the following use of "specification" and "drafting":
What is meant by "hardware specification" and "drafting hardware specification".
Is this something done before circuit/hardware design of after design?
Could you give concrete example which can clearly show what these mean?


texts: Linear regulator LM1084 5.0V capacitors choice

texts:
I'm trying to make power supply for RaspberryPi and another one for usb hub and another for 9 Ping sensors(20mA)+ few servos + few microcontrollers like Atmega328P. I have only LM1084 or LM7805. So my choice is not big and I choose LM1084 as it allows more current.
So it makes 3 "supplies". It all going to be powered by one LiPo 2S 2200mAh(~8V).

So far my choice of capacitors as follows:
on input side it's 0.47uF electrolytic capacitor and on output 0.1uF ceramic cap and 220uF electrolytic. Datasheet says put 10uF tantalum on both sides. I don't have these. Only ceramic. Should I follow datasheet with ceramic caps? Now I'm using values from 7805, my bad. And without load it's 4.99-5.00 and with changing load of 2 servos between 0.320A and 0.630A in second voltage changing like 4.89-4.93 and like this.
What will be better choice of capacitors here? Maybe I should put 10uF ceramic on input not electrolytic?

Or better I just go and buy car cigarette usb adapter and not make any fancy and large things?

simulate this circuit – Schematic created using CircuitLab


texts: Design example for LED driver output that support 0-10V sinking dimmer

texts: I am trying to come up with a device that can connect to 0-10V wall dimmer(sinking) and convert it to corresponding PWM signal. I have trouble understanding how the 0-10V interface has to be designed on the device to support 0-10V sinking dimmers. Please suggest a low cost option. Example circuit will be greatly appreciated.


texts:
Industrial frequency inverters (or "variable speed drives") can be thought in three parts: A mains rectifier, that converts two- or three phase input current to DC, a DC energy storage (large capacitor) and a three phase driver, that converts DC current to three phase AC currents of the wanted frequency.

The mains rectifier is often just a passive rectifier circuit.

The output driver usually is made of microcontroller driven FET bridges.

Question is, if the rectifier stage of one inverter can be removed, and replaced by the same circuit as the output driver stage taken from another inverter. Like we would treat mains power just as another motor.

With right control, the inverter then would become fully symmetric and would be able to feed current either way, from the mains to the motor but also from the motor to mains (recupation).

As the motor is also meant for running of the mains directly, voltage and current of both (motor and mains) somehow fit well, and I guess the driver circuit could serve both of them. Would this be feasable?


texts:
Found this dumped along a trail through the woods... not attached to anything & with some other junk, but nothing that was similar. I'm curious what it is!
Its about 12" / 30cm along the top-bottom axis of the photo.
My first thought was that it is a powerline insulator. But comparing to photos online it actually is quite different in many details, especially the apparent 3 major "limbs" which come out of it -- most seem to just have 2 points of connection, and less elaborate ones than this device. (That said however, there are a lot of variations.)
The white material is a very hard glass or ceramic, the other components mainly seem to be steel.
Where the steel limbs protrude, they mate into the white body via a very dark colored material which I can't identify.
I didn't see any writing or markings at all.
I can add photos of any details if that would be helpful.


texts: Why are there more than one programming channels on PIC32?

texts:
Previously, I was working with PIC16 and PIC18 series, and none of them provided multiple channels for programming. Now, I am designing my first PIC32 circuit, and I'm very confused with these multiple programming/debugging channels.

Why are there more than one of them? As far as I know, programming is a special event, and it is done when doing firmware update, or during development stage, or just after manufacturing process. Neither of these cases require more than one programming channels. Why do they provide 3 or 4 channels for this? I want to leave ICSP pins in my circuit for programming; can I choose either of these channels, or must I prefer a certain one?


texts: Do capacitors conduct electricity while charging?

texts:
I was reading a schematic for a timer circuit, and it made use of a capacitor and a transistor. The description below the schematic explained that the current through the base of the transistor was not enough to switch it on until the capacitor was charged. I am quite confused as to the behavior of capacitors during charging. I have read countless descriptions of the device, and I understand that it stores energy in the electromagnetic field surrounding its component plates. I still do not understand their behavior, though. I have come up with two hypothesis as to why the timer circuit is designed like this:

The capacitor conducts electricity only while charging. While it is charging, the current is directed through the capacitor, ignoring the transistor and going back into the voltage source. After it has charged, the current no longer flows through the capacitor and flows through the transistor instead.
The capacitor conducts electricity only while charged. While it is charging, the circuit is open and electricity flows through neither the capacitor nor the transistor, all of it ending up in the electromagnetic field of the capacitor until it is charged, when the capacitor is able to conduct electricity. Then, the current flows through both the capacitor and the transistor.

Of these two hypothesis based on what I have read, I am leaning towards #1. I would like to know if a capacitor conducts electricity while charging, and if one or neither of these are right, and which one if so. Thank you in advance - I just learned how a transistor works, and now I am struggling with capacitors. :)

Additional information: this question is asked with the perspective of someone who only works with direct current.

Here is a link to the diagram (I had to dig through my browser history): http://www.instructables.com/community/Timer-Circuit/


texts: Meaning of certain symbols and labels in Circuit board PCB schematic design (v2)

texts:
I have a schematic design for a printed/ electronic circuit board. I want to know the meaning of certain symbols/ labels in the schematic design. I have highlighted in the below picture, the relevant areas in green, yellow and grey boxes:

Question 1: In the yellow box, is it a ferrite bead (labelled FB2)? but the schematic symbol is of an inductor. Is it a ferrite bead or an inductor?
Question 2: In the green box, there are 2 grounds, why?
Question 3: In the grey box, there is a symbol for a single pin named 'TESTPT1'. So what does it mean? Do I need a 01 x 01 connector at this place? How will I choose an electronic connector/ component from the market for this 'TESTPT1'?
I would appreciate answer(s) to any/ some or all of above questions.


texts: Do magnets interfere with my DC circuit?

texts:
I have a very simple electrical circuit that contains a 12V DC adapter, a 12V LED strip, and a switch. The catch is, that the LED's are controlled by a sliding door, which presses the switch and completes the circuit when closed. Installing the switch into the door was however a very amateurish DIY project and the best solution I came up with was sticking the button to the side of the metal frame (isolated) using a bunch of neodymium magnets. Surprisingly, it worked out pretty well and isn't at all visible. Because of the specifics, it was also convenient to use the nickel plated magnets as conductors to connect the button, so yes, the magnets are in fact part of the circuit. The thought that this might be a bad idea crossed my mind, but I assumed that since both the magnetic field and the current are static (not AC), it should probably be fine, and if not, I would probably be able to tell right away and do something about it. When I was finished, everything worked perfectly without issue just as I expected. Or so I thought.
Several days later, I noticed that the LED's emit very faint light even when the switch is disconnected. This surprised me greatly. I measured the voltage between the + and - poles of the LED strip, and when on, I got a reading of just below +12 V as expected. However, when supposedly off, I got a stable reading of exactly -41.3 V! I also tried measuring frequency, for which I got values between 150 and 180 Hz. I'm not sure if it wasn't just the multimeter giving random values but it gave a clear 0 when the LED's were on.
What phenomenon is at play here? Should I be concerned and disassemble the contraption? I can provide more details or pictures if necessary.


texts: What would I call this specific type of knob?

texts:
I am looking for a particular type of spring-loaded knob, similar to the thumb wheel you would find on an old Blackberry - but I cannot seem to find an appropriate name to track one down.

I'd like to be able to turn the knob clockwise or counterclockwise to generate a voltage proportional to the angular displacement, then as soon as you release the knob it would be restored back to its "home" position.

I suppose I could approximate one by attaching a torsional spring to a potentiometer, but I figured this has to already exist.

Thanks.


texts:
USB 3.0 has 9 wires.
   4 from USB 2.0  (VCC, GND, D+, D-)
 + 5 new for super (SSTX+/-, SSRX+/-, GND)

My Understandings: (these may not be correct)
- USB 3.0 is separated from USB 2.0 and USB 3.0 doesn't use D+/- for data transmission.
- USB 3.0 Hub structure shows different path between 2.0 and 3.0.
- From USB 3.0 Speed detection procedure, D+/- are not needed once 3.0 speed setup.

I did a experiment to know whether D+/D- can be ignored by 3.0.
   I bought a USB 3.0 extension cable,
     and verify the cable works fine with USB 3.0 memory and USB 3.0 hub.
   I cut D+/D- 2.0 data lines in the middle of the extension.
   There was no USB 3.0 connection. no 2.0 of course.
   I re-bind D+/D- data lines, connection was recovered in both 3.0 and 2.0.
   While connected, cut any of D+ or D- makes connection lost.

From my experiment, D+/D- cannot be ignored even for 3.0 from plugging-in to operating.

Recently lightning cable to USB type C released, and iPad Pro supports 3.0 speed.
lightning cable has 4 data lines: D1, D2, D3, D4.
I'm wondering how it makes USB 3.0.

Please correct if there's any wrong info.


texts: This problem was asked in a paper recently. They have not clearly mentioned the circuit. Assuming a low pass circuit, I tried to draw some waveforms. And I can't think of any other circuit that they are expecting. They gave option (A) as the official answer but I can't understand how they are getting it. Please help me with this.


texts: Transformer fuses for Primary and Secondary

texts:
Good afternoon, I hope that you are all well not withstanding COVID-19.

I have a 230/24v 250VA Transformer which is being used to power 4 x motors drawing a maximum of 20.3 Watts each.

I would like to know what amperage of fuse to use for primary and secondary and whether or not they need to be slow blow?

The data sheet for the transformer can be found here:
https://media.automation24.com/datasheet/en/86345_Data%20Sheet_en.pdf

Many thanks in advance and stay well.


texts: triac dimmer switch failure mode - flickering

texts:
Background

About the switch

In the UK dimmer switches with modules that look like this are quite popular: https://ssli.ebayimg.com/images/g/7f0AAOSwMvtZOrsC/s-l640.jpg
It's a mains light dimmer, usually rated 50W-250W. Having searched the web a bit and disassembled a few, they appear to be triac dimmers.

Wiring

I use these dimmers in rooms with three to five lightbulbs. I have recently replaced the lightbulbs with dimmable LEDs, leaving one halogen in, so load is still 50W+. Without that they flicker when dimmed (my understanding is that triacs have a minimum current requirement).
All fine so far.

Issue

A dimmer switch broke, so I got a replacement.

It worked fine for a few hours, then lights started flickering (my guess is 10-20Hz) and were a bit dimmer. Sometimes flickering stops for a bit, lights get brighter, then starts again etc. IOW, behaviour changes over time, but is never fine.

Switching off/on doesn't help. Dimmer was dialed to full power when this happened. This has happened in multiple rooms (I've moved dimmer switches around to eliminate other factors), and with three replacement dimmer switches. With one of them it took a few days for this fault to develop. After fault develops, that dimmer switch does not work correctly anymore.

Now, the fix seems obvious: source dimmers elsewhere. But I feel uncomfortable not knowing the root cause, and I think this could be an learning experience.

What is happening?

It appears I'm using these dimmers in some incorrect way, although that's not obvious to me. I guess circuit in LEDs could draw too much current through triac in dimmer, but that theory seems weird.


texts:
I am designing an ultralow noise audio board.

On the first PSU PCB (just talking after bridge) I have a CMC to remove switching noise on diodes to undetectable levels (with plenty of capacitance for ripple and inductor to remove high frequency).

This PCB has wires going to main board. I am thinking to use a second CMC on this board so the two CMCs will be in series

My question is:

Should I worry about any impedance characteristic of CMCs? Can I use the same CMC at both places or should I use a lower impendance CMC (lets say 700R) as first CMC while using a 2.2k as a second CMC?


texts: Can I use barrier rectifier as a diode in bulk converter circuit?

texts:
I have this LC circuit which will work under 12V and quite high load (10-20A):

The diode D1 must be a shottky diode but the only similar thing I have at the moment is actually 3-leg MBR3045CT rectifier.

Can I use it as D1 diode visible in the circuit?
Can I connect legs 1 and 3 together to serve as an anode and leg 2 as a cathode? IS this good idea and will it double max amperage it can handle?


texts: I may need to measure reflected power from some PA at 868 MHz with a maximum power of 5W and there are readily available SMD directional couplers to buy. However, I found only 90 deg. couplers on immediate stock and I wonder if can I measure vswr (maybe combine two?) with them. Actually I intend to use in some protective stage that suppose to keep the PA safe.


texts: Mobility of electrons vs holes in semiconductors (intrinsic vs extrinsic)

texts:
I was reading my class notes and it was written that electrons are more mobile than holes because the effective mass of electrons are lower than that of holes. (μ=eτ/m*)
I checked online to find the relative effective masses of electrons vs holes and in intrinsic semiconductors (like Ge and Si) and found out that the effective mass of electrons are higher than that of holes. So is the relative mobility of electrons still higher than holes in this case (and the collision time constant for electrons much higher than holes to compensate for the lesser effective mass)?
Besides I came across an article on this site which explains that since mobility of electrons are due to electrons that move in the conduction band which is higher than holes as they are much freer than the electrons which move in the valence band (whose movements dictates the movement of holes) due to columbic attraction of the electrons and holes. How can I relate this answer to effective mass?


texts: Capacitor quenching circuit across Brush and Commutator of DC motor

texts:
To reduce the spark between brush and commutator segment there is capacitor and resistor spark quenching circuit is placed between each commutator segments.
please find below images for detail idea

please help me about mathematical equations involved behind this to get idea how exactly spark reduces(damping oscillation concept  and  how it is applicable to below circuit) and how to determine resistance and capacitance values..?

i am from mechanical engineering background & done some priliminary studies but wants to know details phenomena about this
thanks


texts: ATX 12V power supply fan required or not at low current?

texts: Does ATX power supply really need its cooling fan when drawing only 3A at the +12V rail? I know that the fan is mandatory when it's running a computer that draws 200 Watts and above but is the fan required if the load is just 36W?


texts: How to correctly set output voltage with LT3080

texts:
I have designed the schematic below, wanting to build a simple power supply for a project. Problem is, the LT3080 is outputting around 15V no matter what R1 I use.

Trying to find the root cause, I have removed all components following the LT3080 (except for R1), but to no avail.

I am measuring 11Vac across the transformer (it is rated 7.5V @ 1.5VA) and 15Vdc across the bridge. Measuring the tab of the LT3080 gives 14.7V (same voltage if I measure across C4. All of this with a 470kO R1... which if I'm not mistaken should output 4.7V

Can anyone shed some light on this?


texts:
I'm "building" a regulated linear power supply using LM317, Min(1.25V) Max(24V) Max 1.5A, and I have like +/- 30.88V (10% of ripple(3.25v), 32.5V Maximum and 29.25V minimum, medium 30.88V) in input of the LM317(I'm using 4700uF electrolytic cap), but assuming that LM317 have a huge ripple rejection (66dB, that reduces 3.4v to 1.62mv of ripple)  I will say that I have like 32.5V getting in my LM317, my power dissipation at wrost case (in LM317) if I am correct, its something like 46.48 watts (P = 32.5V - 1.25V) x 1.5A so my question is, is it 46,87W to much and problably will I need a heat sink to hold it right?

Sorry guys I'm, new in this game :p Ty everyone!

(I'm using a 24V/3A transformer, bridge rectifier made with 4x1N5408)


texts: When we raise a signal to a power n, does the bandwidth always gets multiplied by n?

texts:
I know that when we have a message signal

$$m(t) = \cos(\omega t)$$

when it gets squared, its bandwidth gets doubled, because

$$\cos^2(\omega t) = \frac{1}{2}+\frac{1}{2}\cos(2\omega t)$$

But is this true to every possible signal m(t)? What if I raise it to an arbitrary power n?


texts:
I was researching in psychophysic on optic experiment and I stumble upon my  laptop manufacturer'screen specs. There is a 60hz refresh rate with exponentially decaying lums intensity between each tick.
Wouldn't it be visually nicer if the digital video signal were converted to continuous analogical first and then feed each led continuously as it happen in audio transducer ?


texts: MOSFET for switching ~12V automotive application with 3.3V microcontroller

texts:
I’m trying to find a mosfet that will let me switch a 12-14V source from a car battery to ground using a 3.3V micro controller with minimal resistance added. I believe I understand that the gate voltage needs to be 3.3 V or less and it needs to be an n mosfet, but I’m not really sure what I need apart from that when I look at specs on component websites. Any help is appreciated. Let me know what other info is needed because I don’t really even know. My electrical skills are almost exclusively with automotive applications, so MOSFETs are pretty far out of my realm.
The goal here is to replace the ignition functions of my engine computer (which has failed) with a secondary computer. I will be putting resistors into the normal circuit to act as dummies to fool the original computer into thinking it is still hooked up. I’m then planning on driving 9 components with the mosfets: 6 fuel injectors and 3 ignition coils. If I remember correctly these injectors are around 12 ohms and coils .8 . The positive side comes from the battery through a relay and fuse goes to the injectors and coils. Then from the coils and injectors I’ll go through the mosfet to ground. I’ll try to draw a schematic of what I am going for in a bit. Mosfet seemed like the way to go but if there’s a better option let me know. I need something that switches very quickly and isn’t too expensive or likely to fail.
Honestly I may need to do two different setups: one for the injectors where the amps are gonna be decently low and one for the higher amp coil circuits. Just needs to be fast switching and would like it to be as simple as possible.


texts: Power Cable Strain Relief Solution Needed for Restoring Vintage Electronics

texts:
I recently acquired a vintage Tektronix active probe from 1969, and I'm in the process of restoring and modding it for modern scopes. The unit is in good shape, but the connector is no longer in production and there's no replacement. So the decision is made to preserve the original cable unaltered as a backup part, and install a new one.

I thought the process should be straightforward, until I realize there is no way to reliably secure the new cable in place. The quality of the original cable assembly is high: the cable itself is around 3.1mm, with a molded strain relief with a notch at its termination. The cable enters the enclosure through a 7mm hole, and is clamped at the notch of the strain relief by its frame and fixed with a screw. It provides robust protections against pulling the cable in or out. After all, nothing is damaged after 50 years.

What is a good solution to provide reliable strain relief to secure my cable to the hole in the enclosure, and keep the cable intact for the next decade?

I've reviewed Securing electrical cables to holes in enclosures?, unfortunately, the answers are not useful in this scenario.

Molded cables - Impossible??
Entry points designed to hold the cable - Need custom enclosure to begin with, impossible.
Use of Cord Grips or Cable Glands - Too large to fit??
Cable grommets - Doesn't provide any relief from pushing or pulling.

Consider that none of the solution applies to the case of securing a cable on a general enclosure, I believe my problem is related to electronics design, and is still a general question of interest.

In addition, I believe using glue is not a reliable solution and it would make the device much more difficult to service if a problem appears in the future, I would also avoid drilling, as it can be destructive for the enclosure and the front panel, in this case, failure is not an option.


texts: Does a motor really need all this circuit to run?

texts:
This is the pcb of an Ikea screwdriver, you can see I desoldered the 18650 battery, from B+ and B-, and desoldered the motor from the legs of the switch which is on the other side. So the circuit should manage the charging of the battery and a couple of leds, other than the motor.

What I am thinking is, can I drive the motor directly from the battery and charge it with an external charger, or some of the parts are needed for the motor itself?


texts:
I'm tasked to design an audio amplifier with a class AB amp as the last stage.
For the first two stages, CE-CE, the gain amounts to 100+. But when connected to the driver stage, the output suddenly drops drastically to uV.

We haven't been taught AB Amps so the schematic I have is just taken from other internet sites. Can someone explain why the gain gets cut?


texts:
im currently picking a mosfet for a project.
Im looking for a mosfet that has an Id of 10 amps+ at 3.3v. I found the 16NF06L but have a problem understanding the datasheet. It says that Id is 16A. Figure 5 shows (to my understanding) that at 3.3v Vgs the mosfet should be able to handle around 13 Amps (with Vds > 2V).
So far so good. But when i look at the RDS(on) line in the table the test condition colum shows that Id is 8A at both 5V and 10V Vgs. That seems to contradict what the figure shows. What does ID mean in the context of RDS(on)? To my understanding Id always means max. current under given conditions (Vgs, Temp, Vds etc.). I only started learing about mosfets today, so maybe im missing out on something obvious.
Hope you can help.


texts: Why do R and C have to be small for differentiator circuit

texts:
I'm a beginner studying The Art of Electronics, and on page 25 they introduce the differentiator.  Basic circuit like so:

They give the complete equation:

$$
I = C \frac{d}{dt}(V_{in} - V) = {V\over R}
$$

I understand this so far.  But then they say: if we choose R and C small
enough so that \$\frac{dV}{dt} \ll \frac{dV_{in}}{dt}\$, then...

$$
C\frac{dV_{in}}{dt} \approx \frac{V}{R}
$$

This I don't follow. Can someone elaborate or explain a bit more? I see why the above equation makes it a differentiator -- V is proportional to \$\frac{dV_{in}}{dt}\$.  But why does a small R and C cause the one derivative to me much less than the other?


texts: Total voltage error at the output of the Op-Amp

texts:
I have this circuit (shown below), I need to calculate the total error voltage at the output of the Op-Amp due to R3 and Vos.

U1 is the LM741, which has Vos = 5mV and ib = 80nA.
Till now I’ve calculated the error voltage contribution for Vos as following;
Vo = Vos * (1 + Rf/R1)
Vo = 5m * (1 + 47k/2k)
Vo = 122.5mV
How can I calculate the error voltage contribution for R3?
Thanks !


texts:
Well, the question is the title: Is it worth really buying a Fluke for hobbyist use?

I have a cheap meter at the moment. Is it worth spending a 3 figure sum on a nice, shiny, new Fluke? I honestly don't think so, but I'm curious what other's opinions are.


texts:
I am working on a project that requires a power management board. I use a solar panel (or a wind turbine,) a battery and a Raspberry Pi that uses a 4G hat.
I need a board that manages the power source, converts the voltage out of the solar panel (or from AC power) and the battery to 5V and sends feedback to the Raspberry Pi about the battery charge or the solar panel efficiency.
I studied electrical engineering for 2 years but is was 25 years ago and I never used it in my professional life as I became a software engeneer.
I don't know where to start to design my own board by myself. I found some information about what components would be useful (such as INA260 for power measurement) but what are the online tools and the ressources that you can use when you want to design something like that and you're not a pro?


texts: How exactly does switched capacitor system work, what exactly is the detail of the primitive that switches

texts:
I have been seeing these switched capacitor circuits for some time now and have even seen Z-transform being used to model how these circuits behave. While I can see that there is some capacitor that switches, what exactly is the mystery behind this 3 terminal device one terminal of which comes from some sort of clock. How is this clock generated?

I am wondering how do these things work from within a circuit but don't know how to get a good thorough answer.


texts:
I'm using the STM32F4DISCOVERY board and I am trying to read a file from a micro SD card, and treat the data. I'm using the following functions

int main(void)
{

  int i = 0;
  HAL_Init();

  /* Configure the system clock */
  SystemClock_Config();

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_ADC1_Init();
  MX_SDIO_SD_Init();
  MX_TIM10_Init();
  MX_FATFS_Init();
  MX_USART2_UART_Init();
  create_filter_bank();

  ret = f_mount(&filesystem, buff_mount, 1);
  ret = f_open(&file, WANTED, FA_READ);
  ret = f_read(&file, header, 78, &br);
  ret = acquire_voice_from_file(&file);
  f_sync(&file);
  f_close(&file);
  // Some other code
}

FRESULT acquire_voice_from_file(FIL* file){

  file_pointer = HEADER_WAV_SIZE;
  acquired_frames = 0;
  FRESULT read_res;
  while(acquired_frames < NUM_ACQUIRE_FRAMES){
    file_pointer += FFT_SIGNAL_BYTES/2; // Need a correlation between frames
    read_res = read_frame_from_file(file);
    acquired_frames++;
    // Some Other Code
  }
  return read_res;
}
FRESULT read_frame_from_file(FIL* file){

  int i = 0;
  FRESULT res;
  res = f_lseek(file, file_pointer);
  res = f_read(file, bytes, FFT_SIGNAL_BYTES, &br);
  if(res != FR_OK){
    return res;
  }
  for(i = 0; i < FFT_SIGNAL_LENGTH; i++){
    curr_frame[i] = (bytes[2*i+1] << 8) + bytes[2*i];
    // Multiplying by Hamming window
    curr_frame[i] *= (0.54 - 0.46*cos(2*PI*i/((float)FFT_SIGNAL_LENGTH)));
  }
  return res;
}

All the constant values such as WANTED, FFT_SIGNAL_BYTES, and so on, are declared on the header file correctly. In the main function, f_mount, f_open, and f_read, return the result FR_OK and the data is correctly read. But then in the function "acquire_voice_from_file", one or two frames are successfully read, and then I get the value FR_DISK_ERR from the function f_read in the function "read_frame_from_file". I assume that my hardware configuration is alright since the first bytes are read correctly, but I don't manage to solve the issue and read correctly the next frames. The size of the frame I'm trying to read is 2048 bytes (FFT_SIGNAL_BYTES = 2048). Is there an issue to read big files with FATFS ? And if so, is there a solution ? Many thanks for your help.


texts: 120v DC Agitator motor, 240v 5500w heating element

texts:
Full disclosure: Not an electrician, mostly clueless.

Setting: Home Brewing Beer

Short:
120v DC variable drive motor running full tilt when 240v AC 5500w element is connected to mash tun.

Long:
I have a 50 gallon brew kettle with a 240v 5500w AC heating element. The element has variable power supply. Recently I added a 120v DC variable speed motor to agitate the mash (stirring 50 gallons of mash by hand gets really old). The motor work appropriately when the heating element is not attached to a power supply; I can adjust the speed of the motor.

When the heating element is attached to its power supply, the agitator motor runs at full speed, and cannot be adjusted. I spoke with the manufacturer and they suggested that I have an electrician come out.

My house was built in the 20's and has lots of "character". Many of the circuits are not grounded. That being said, I am (fairly) certain the circuit that the agitator is running on is grounded, as well as the heating element.

Thoughts?
Places to start trouble-shooting?


texts: What is the easiest way to make a stepper motor go?

texts: What is the easiest/ cheapest way to make that motor move like a dc hobby motor would when connected to a battery? Speed doesn't matter. I just want it to infinitely rotate.


texts: How to test if a, in circuit, complementary darling transistor is still functioning properly?

texts:
I think a transistor broke down. My knowledge of electronics is not sufficient to solve my issue, so it seems. Hopefully some better educated mind can help me on this.

This question is about troubleshooting a PWM signal to a fan of this board (Eagle file) from Arduino pin 7 to Transistor Q4 to PWM terminal. Below is the piece of the schematics its about:

Background info (not required to read though):
I've got this PCB (Ultimaker 1.5.4 from 3D printer) and I think I short circuited a fan output. It is a couple of years ago already it happened. So I am not 100% sure, I hooked up an external power supply to power the fan instead. But now I want to have the fan driven by the PCB again and not by the external power source (as the software sometimes lowers the speed or turns of the fan completely, depending on what is printed). Anyway, currently it is not working to drive the fan by the PCB. It is driven by an Arduino Mega 2560 by a PWM (so says the PCB) through a BD679 FROM ST, which apparently is a complementary darlington transistor. I've only got some experience with MOSFETs and known that when the gate is driven by a voltage too high, the resistance between some pins become practically 0, meaning it broke down. Or they just exploded and it was very obvious what broke down.

Info of measurement:
Looking at this datasheet. and a multimeter I read the following on the pins of the BD679.
Resistance
E-C=unlimited
C-B=unlimited
E-B=9.19kOhm

EDIT:
With the diode test function I measure the following always starting with negative left, positive right:

E-C=1 (no read out)
E-B=1269
C-B=906
C-E=768
B-E=1 (no read out)
B-C=1 (no read out)

Question:
Do you think that these are normal readings for this complementary darling transistor?

EDIT 2:
I have tested the Arduino+PCB with an oscilloscope. While setup, I could send a GCODE to drive the PWM responsible to drive the fan. I see that the PWM signal at the Arduino (port 7) is correct, its duty cycle corresponds to what was commanded, and is 5V. The PWM pin of the Arduino to the transistor is connected with a 1Kohm resistor. The same duty cycle signal is found at the Base of the transistor at 1.28v. This I understand. And also at the Collector of the transistor at 960mv, this I do not understand. The signal at the Collector has the same frequency and duty cycle as the signal on the Base of the transistor. The emitter is equal to GND, which I understand. Now when I measure the PWM port that would be connected to a (12v fan) I measure 19.6v, the same as the power supply. The negative terminal of the fan connection shows the 960mv which is equal to the Collector of the transistor. That it is equal to the connector of the transistor I understand as it is directly connected. When I connect a 24vdc fan to the terminal it is not spinning. Although I measure 19.6v on the positive lead and the 960mv PWM signal on the negative lead of the terminal. Can I conclude that the transistor broke down because it is not sinking any current anymore?

Thank you.


texts:
I would like to use the ZXLD1350 LED driver IC to provide constant current to some NiMH batteries to charge them.
However the negative terminal of the LEDs go to an inductor instead of ground.
My aim is to swap the LEDs below for my battery, however when ZXLD1350 is off, I need my negative battery terminal to go down to ground.
I tried making a circuit that does this with a depletion-mode P-MOS but they are quite hard to source and I'm not entirely sure if this is a viable way to do this.
Is there something else I can use instead of a depletion pmos?
Is there a better solution to this (assuming one has to use a led IC)

Here's an image of what I've designed so far:


texts:
I am working on a comparator circuit for converting a small AC signal to a digital (square) signal. The circuit is meant to be used in a strong magnetic environment, so the casing should not have ferromagnetic material such as Fe/Ni etc.

I am using a chip LMH7220MK/NOPB, with Ag plated lead, however when I test with a magnet the chip is magnetically attracted.

Is there any specific supplier or packaging option I can look for to choose my IC (comparator/counter) which are made of non magnetic material?

Any advice would be greatly appreciated. Thanks.


texts: Is this lab power supply linear or switch mode type?

texts:
I'm using a lab power supply which has a manual here. It has the following block diagram:

From the manual or the block diagram can we infer whether the supply is made up of switch mode or linear type of supply? If it is impossible from the manual or the diagram, can one perform a test to verify this?