texts: Wifi functions crashing ESP32-WROOM-32 based board

texts:
I've designed a custom PCB which uses the ESP32-WROOM-32 module. I'm using arduino to help validate the board, and I am able to run very simple programs on it successfully (ex. serial echo, Blink, etc...)
Where I'm having trouble is running any Wifi programs on it. For example, when I load the Wifi Scan example program, I receive the following output.
rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:2
load:0x3fff0018,len:4
load:0x3fff001c,len:1216
ho 0 tail 12 room 4
load:0x40078000,len:10864
load:0x40080400,len:6404
entry 0x400806b8
[W][esp32-hal-psram.c:30] psramInit(): PSRAM init failed!
[D][WiFiGeneric.cpp:332] _eventCallback(): Event: 0 - WIFI_READY
[D][WiFiGeneric.cpp:332] _eventCallback(): Event: 2 - STA_START

Most times it just stops here, sometimes it will restart and repeat a few times. Occasionally it will cause a kernel and my Mac will restart.
Here is my schematic:

U1 is the ESP32-WROOM-32
U4 is a CH340C USB to serial chip
IC1 is a HT7833 LDO
Lat thing, I've looked at the logic levels on the bootstrapping pins and don't see anything out of the ordinary:
GPIO 0: High
GPIO 2: Low
GPIO 4: Low
GPIO 5: High
GPIO 12: Low
GPIO 15: High
I've been trying to troubleshoot this problem for the past three days and I'm stumped. Any help would be appreciated.
EDIT 1: Here's a picture of the o-scope on VCC. The voltage variance I see is 2.8v on the low end and 3.8v on the high end.

EDIT 2: Capacitor shown on the output of IC1 are positioned extremely closely to U1. See picture:


texts: Can I get a square-wave inverter as source for my laptop charger?

texts:
I have a solar power which it's power is stored in 12V automobile battery. And use inverter to produce 220V AC to feed common equipments. The inverter as shows symbolic gets a square wave. It mentioned on the charger that its frequency is 50-60Hz.

As we know square waves have harmonics beside main frequency, Is it safe to feed my laptop charger by this inverter?

p.s: My laptop charger is: Toshiba PA3714U-1ACA; Input: 100-240V~1.5A; 50-60Hz


texts: Can i drive 24V (0,5A) motor with IRLZ44N

texts:
I'm not sure if I can drive a 24V (0.5A) dc motor with the following circuits?

I fear that there will be burned too much power in the transistor when the supply is 24V (I will become super hot).

Here is a link to the datasheet for the IRLZ44N: http://www.irf.com/product-info/datasheets/data/irlz44n.pdf

Thanks for the help!


texts: Questions about pushbuttons - through-hole or SMD

texts:
I am designing an Arduino shield in KiCAD.
I have to have a reset button, so I got these buttons.

As you can see, the pins are really long (I extended the pins in one of them.)
How are these buttons used? Are they through hole or SMD components?
I plan on using SMD components.


texts: Interpreting Maximum Power of a MOSFET from the datasheet

texts:
A MOSFET has the following datasheet: http://www.vishay.com/docs/91015/sihf510.pdf

which states for the max. ratings:

Maximum Power Dissipation = 43W

Continuous Drain Current = 4A (at 100°C)

where

RDS(on) = 0.54 ohm

What I interpret from this info is: In continuous operation this MOSFET should not exceed 4A. And since RDS(on) = 0.54 ohm, the power at max allowable current:

P = Imax^2*R so P = 8.64W (I think this is the max power of MOSFET can handle without any heatsink?)

So if I obey the datasheet I find 8.64W but the datasheet says the Maximum Power Dissipation is 43W.

Firstly:

Does that mean the maximum power dissipated by a big heatsink cannot be more than 43-8.64 = 34.36W ?

And secondly datasheets says:

"The TO-220AB package is universally preferred for all
commercial-industrial applications at power dissipation
levels to approximately 50 W" Is 43W approximately 50W? What is this 50W?


texts: 30N06L N-channel mosfet switching heavy load interfering with micro-controller circuit

texts:
I have a microcontroller that I want to use to switch on/off a heavy load (a car horn) with a 30N06L N-channel mosfet. Everything works when running a load of 4Kohms (with the car battery at 12v), but when I move to the heavy load of the horn, then things go awry. I can hear an initial honk, but then the horn stops. I am guessing that the high current powering the horn is causing interference with the rest of the circuit somehow. Does anyone have experience with this?

Also, the reason I am going with this particular mosfet is because it is what I had laying around. If it makes more sense to go to a similar P-Channel mosfet, I can order a few.

simulate this circuit – Schematic created using CircuitLab


texts: Need help understanding an universal pin driver schematic

texts:
I was studying a schematic of an universal 48-pin device programmer, and while most of it seems pretty straightforward to me, I have trouble understanding the reasons behind some of the decisions made by the original author for the pin driver circuit. Below is the block diagram of the programmer:

Combined schematic for a single pin looks like this:

simulate this circuit – Schematic created using CircuitLab

Each of the 48 pins can be connected to GND, VCCX (a programmable voltage VCC rail), VPP (a programmable voltage VPP rail), or act as an input pin. The questions I am asking for help with are (please refer to full schematic linked above):

Why use an ULN2003L to control base of QVPP to switch the VPP voltage for a pin? Why not drive the base directly from the output of SN74LVTH273DW?
What is the function of schottky diode in VCCX switch?
Each pin is connected to a FPGA via two resistors and a diode (BAV70), see the block diagram. How is the FPGA being protected from high voltage (e.g. 5 volts) potentially being output by programmed chip to some of its pins?
All pins are also connected to a common PULLUP (which can be switched to be either pull-up or pull-down by the MCU), but I don't get why would one need to pull all pins at once to VCCX or GND, and why wouldn't doing so interfere with supplying power to the chip's power supply pins? Or, perhaps the PULLUP function is there for a self-test to change state of all pins and read them back in FPGA?

Thanks in advance!


texts: What are the limitations of IMU sensor devices?

texts:
The Oculus Rift DK2 virtual reality headset uses an IR camera in conjunction with built-in accelerometer/gyro/magnetometer for accurate head/motion tracking. The previous version (DK1) used only an IMU device and had less accurate head-tracking and suffered from drift errors.

Why are current IMU devices (accelerometers, gyros etc) unable to accurately measure motion? What limitations exist with these devices and why? I understand gyros are accurate over short time scales, but have drift errors over larger times and require an accelerometer or magnetometer to correct this drift. Whereas accelerometers are unprecise over short durations of time and require averaging functions to output meaningful data.

Also, would it be possible to use multiple IMU devices in specific geometric locations to get more accurate and faster motion data? Regarding head-tracking, what other solutions are there using IMU devices (with shortest delay possible being the key factor in design)?


texts: What happens when base voltage is higher than the collector voltage in a bipolar NPN transistor?

texts: Does the base voltage has to always be (0.7v) in order for a bipolar NPN transistor to work? what happens if the base voltage increases or decreases? I'm really not into the technical stuff I'm just curious about how electrons exactly work in transistors. Like what if the base voltage is more than the collector's one, wouldn't electrons just flow through the base current and completely ignore the collector?


texts: Audible noise coming from Inductor when using LT3760 driver circuit

texts: I have an audible noise from inductor when I use LT3760. When PWM is 20kHz, the noise is at 10kHz. Whenever I switch PWM, the noise is at half of PWM. Where does it come from ?


texts: What is the difference between a PLL and a DLL?

texts: Phase Locked Loops (PLL's) and Delay Locked Loops (DLL) are used in various applications but there isn't yet a salient discussion of the key aspects of these circuits, how they operate, in what applications they might be used, the comparison between the two circuits and why one should be used vs. the other.


texts: Impementation of Boolean function using decoders

texts:
I need help with implementation of this Boolean function:

F(A,B,C,D)=П(0,4,6,7,9,11,12,13,15), (conjunctive normal form)

with minimum number of decoders 2 to 4 and one NOR gate.

Using Shannon's expansion theorem with two levels of integration (without NOR gate):

My question is how to implement NOR gate with these decoders.
Thanks for replies.


texts: Can a voltage peak detector circuit detect square wave overshoot voltage?

texts:
I'm building a simple inverter with an inductive-capacitive load.
I wonder if I have overshoot voltage like this on my IGBT:

I want to detect this overshoot, but since I don’t have an oscilloscope I'm struggling with this issue. I'm trying to find another way to detect this overshoot and a peak detector circuit came to mind.
Can I use a peak detector circuit to detect this overshoot or can you give me a better circuit to detect this ringing overshoot?
Note: I don’t want to get rid this overshoot, I want to detect it by taking feedback using a current transformer and then feed it to the detector circuit because I want to use a phase lead circuit on my logic driver to get rid this overshoot, so perfect zero current switching (ZCS) can be achieved.


texts:
I've the following circuit:

simulate this circuit – Schematic created using CircuitLab

The capacitor is charged up to 10 V according to the following formula (when the switch is closed):

$$\text{V}_\text{C}\left(t\right)=\hat{\text{u}}\cdot\left(1-\exp\left(-\frac{t}{\text{CR}_1}\right)\right)\tag1$$

Now, when I open the switch the capacitor will discharge its energy in the resistors that are standing in series with the capacitor.

To find the current that runs in the circuit when I open the switch is:

$$\text{V}_\text{C}\left(t\right)+\text{V}_{\text{R}_1}\left(t\right)+\text{V}_{\text{R}_2}\left(t\right)=0\tag2$$

Writing that in terms of the the current (using Ohm's law and \$\text{I}_\text{C}\left(t\right)=\text{C}\cdot\text{V}'_\text{C}\left(t\right)\$) in the circuit gives:

$$\text{I}_\text{C}\left(t\right)\cdot\frac{1}{\text{C}}+\text{I}_{\text{R}_1}'\left(t\right)\cdot\text{R}_2+\text{I}_{\text{R}_2}'\left(t\right)\cdot\text{R}_2=0\tag3$$

Now, if I define a new time \$t=0\$ when I open the switch, the initial current in the capacitor is equal to \$0\$ amps. So \$\text{I}_\text{C}\left(0\right)=0\$. Now it is a series circuit (when the switch is open) so I can rewrite:

$$\text{I}\left(t\right)\cdot\frac{1}{\text{C}}+\text{I}'\left(t\right)\cdot\text{R}_2+\text{I}'\left(t\right)\cdot\text{R}_2=0\tag4$$

  Now, when I use the initial condition (to solve the DE given in equation \$(4)\$), I get the current in the circuit (after the switch is opened) equals \$0\$, but that is not possible. What is mistake here?


texts: How can a processing delay be explicitly declared in VHDL?

texts:
Taking as an example the following simple multiplication:

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

entity multiplier is
  port(
    clk : in std_logic;
    a   : in std_logic_vector(15 downto 0);
    b   : in std_logic_vector(15 downto 0);
    p   : out std_logic_vector(31 downto 0)
    -- ready : out std_logic;
  );
end multiplier;

architecture IMP of multiplier is

begin
  process (clk)
  begin
    if clk'event and clk = '1' then
      p <= a * b;
    -- ready <= '1';
    -- else
    -- ready <= '0';
    end if;
  end process;
end IMP;

At the raising edge of input clock, 'a' and 'b' are assumed to be valid, and the product 'p' is processed. For more complex and slower processes, what are the options in VHDL to have an 'operation finished' output?

I've put the ready symbol just as a way to try to exemplify what I'm trying to achieve. I'm assuming that the process could be complicated enough to last more than a clock period.


texts:
MCUs have maximum source/sink capabilities per GPIO, maximum source/sink currents through the VDD/VSS pins, and have maximum total power dissipation in function of package.

These parameters are all explicitly declared in the datasheet.  For instance, the high current ports on the PIC16 family can output 100mA per pin, the sum of all currents going through the VDD/VSS pins must be less than 250mA, and the package can dissipate 800mW.

Does this mean that at any given time the GPIOs can never output more than 100mA on the high current pins, or that this limit can be surpassed (i.e. having a short high current pulse) as long as the total package power dissipation is less than 800mW?

EXAMPLE

Let me give an example to better illustrate my question.

Suppose I have this circuit:

simulate this circuit – Schematic created using CircuitLab

The datasheet for the IRF8736 states that the input capacitance (Ciss) is 2315pF @ Vds=15V (i.e. non-zero) and a gate resistance of 2.2Ohms, so the instant the GPIO signal goes high, the instantaneous current will be:

\$i = V / R\$

\$i = (Vdriver - Vgate) / Rgate\$

\$i = (5V - 0V) / 2.2Ohms\$

\$i = 2.27A\$

This is way larger than the 100mA maximum allowable current for the GPIO pin.

However, if we look at the power consumed by the driver to drive this signal:

\$Pdriver = Vgate * Qg * Fsw\$

\$Pdriver = 5V * 26nC * 250kHz\$

\$Pdriver = 32.5mW\$

Which is far below the total 800mW allowable by the MCU.

So in this particular case, which parameter should be followed to respect the limits of the MCU?  The maximum allowable GPIO pin current, or the total allowable package dissipated power?  I wish there was a total allowable power dissipation per GPIO.


texts:
I'm trying to configure an ADC (ADC12j4000) and I need to configure the number of serial lanes (denoted as L in the page 39 of the datasheet). For some factors as D, DDR, P54, K... I can see how to configure them in the page 70 of the datasheet, where by some address, I can configure the ADC for the desired values. But as I mentioned before, I am not able to configure the number of lanes. Is there any other way to do it?

Any help is appreciated! Thanks for all!


texts: How do diodes and capacitors reduce Crossover distortion?

texts:
I found this diagram about Class AB Amplifiers and the reduction of crossover distortion:

http://www.electronics-tutorials.ws/amplifier/amp_7.html

  This pre-biasing voltage either for a transformer or transformerless amplifier circuit, has the effect of moving the amplifiers Q-point past the original cut-off point thus allowing each transistor to operate within its active region for slightly more than half or 180° of each half cycle. In other words 180° + Bias. The amount of diode biasing voltage present at the base terminal of the transistor can be increased in multiples by adding additional diodes in series. This then produces an amplifier circuit commonly called a Class AB Amplifier and its biasing arrangement is given below.

I don't understand the explanation of how the diodes and the capacitors reduce the Crossover distortion. Each transistor (npn and pnp) should cover 180 degrees a sine, why doesn't 180 + bias remove the complete distortion, what have the capacitors and diodes to do with this?
I read about the diodes compensating for the transistor voltage drop of twice 2× 0.6V How does this exactly work? How does the capacitor smooth the signal?


texts:
I've been reading the data sheet for a power over Ethernet module, the si3402-B.

There is an application schematic which shows how the system is typically designed. However, it says it's a simplified schematic and for full info see the reference design of the evaluation board. It shows the circuit design of the evaluation board which is very confusing, because I don't know what to implement from it; the reference design or the simplified version?

I'm sorry for this question, as I am not so good in hardware design.

Hint: The reference design is not providing any features except input and output, just like the simplified version, but as a more complex view.

Thanks in advance!


texts: How do I do signal comparison without using opamp?

texts:
I want to remove the opamp IC seen in the schematic below with the least number of transistors possible in order to simplify the circuit, reduce cost and increase switching performance when used with high frequency input.

The new comparator must give digital output unlike the standard difference amplifier circuit does.

How do I do this replacement?

This will be a bridge rectifier circuit done with MOSFETs. Dir1 is supposed to be logic-high only when \$V_{ac}>0\$. And, Dir2 must be logic-high only when \$V_{ac}<0\$. VCC1 is isolated from the AC grid.


texts:
In the current mirror given below

I can see that the Iref produced strongly depends on Vdd whihc is the supply.
In the diag shown below which is power supply independent as they call it,

I do not understand how this is power supply independent. The PMOS M3 and M4 anre supply dependent as M3 is purely a diode connected transistor and it strongly depends on the supply. So my question is what makes this set up power supply independent or in other words less sensitive to the power supply ?


texts: What exactly is this op amp being used to do? Bandpass filter?

texts:
I am trying to identify the major functions of the different portions of this "clap on, clap off" circuit for a project. It's unclear to me what the purpose is of the section circled in orange.
I understand that the second op amp's purpose is to be a half wave rectifier and that the third op amp is meant to be a difference amplifier, but the purpose of the first op amp (IC1A) is not very clear. Any help or corrections to my understanding would be greatly appreciated.


texts:
I want to make a plane for my supply on my PCB and a plane for my MCU to isolate the MCU from the power supply noise.

I found this article in Altium designer resource:

But it isn't clear how the split plane tool work. Can someone explain it in a different manner?

[EDIT]

This is a picture how I see the planes:


texts: Why are there metal links between the discs of an overhead line insulators?

texts: They form interlink capacitance and reduce the string efficiency. A lot of other non metallic strong materials can be used instead.


texts:
What's a good utility to convert gerbers to DXF/DWG?

The reason I ask: I'd like to create gerbers to give to mechanical engineers for use in SolidWorks to look for interference due to solder fillets on pads and other interferences. I'm using PADS Layout and it has a DXF export but the output is messy and the export utility offers few options to control the DXF output.

A gerber to DXF conversion utility could provide enough flexibility and control what goes into the DXF.

I'd welcome insights or suggestions to close the EE / ME gap - methods to get realistic models of PCBs into 3D cad.

Meanwhile, I'll try a free trial of ViewMate Pro.


texts: I am attempting to design a PR control feedback loop for a grid tie inverter. The math checks out but I can't seem to convert the transfer function and/or block diagram into an actual electrical circuit. Please find the block and transfer function attached. I would like to get an op amp circuit to implement this


texts: STM32: Saving 50Mbit/s data in sdram or sd card

texts: Could STM32f429 save image data to sdram or sd card? Camera module outputs its data at a data rate of 50Mbit/s via 8 parallel ports. What I want to do is to save this data into the SDRAM or SD card as a file. It doesn't have to be sequence of files, because I need just one frame. In order to access the sd card, I would use SPI. But I wonder if there is any issue in this process. For example, one said that interrupts in cpu cause data loss and I must find FPGA or CPLD. But I'm afraid that I couldn't understand what he meant.


texts: High side switch load isn't working as intended per datasheet. The output is always high at 12V

texts:
I bought a high side load switch from Mouser, and per the datasheet, I added 13kohms for R1, connected Pin 1 directly to GND. The input (ON/OFF) at Pin 5 is a 5V pulse with a frequency of 20Hz and the input (Vin) at Pin 4 is 12V DC.
I don't know why but the output remains high at 12Vdc. I would like to see my Vout switching between 12V to 0V since my ON/OFF input is a 5V, 20Hz pulse signal. Not sure what I have done wrong.

[][]


texts: Hello I'm struggling with calculation of BLDC motor current. I'm using MP6540 driver for controlling BLDC. I can measure voltage (adc) and after using appropriate formula from datasheet I got current results in all 3 phases. But I'm not sure that results are fine. Adc give new voltage every ~714nS. My question is what I missing, how to calculate current of the BLDC motor when I have 3 reading from 3 phases? I need idea how to calculate current in BLDC motor when I have 3 reading from 3 phases general. Any idea is welcome


texts: Generate identical positve going and negative going pulses/spikes at the same time

texts:
I am interested in building a circuit to generate a sharp positive pulse and an identical negative pulse at the same time with a peak of about 10 to 200 V. So when I say sharp I would like a rise time of 10 ns or better. The pulse could drop off over a longer timescale and I don't care too much about the actual pulse shape, I just want the pulses to be equal and opposite.

I can supply an input pulse of 0-200 V (from 0 to +200V) and was trying to think of a way using passive components, capacitors and resistors, to differentiate the pulse or something to get +ve and -ve outputs at the same time, but, I can only think of ways to generate a shark positive spike at the beginning of the pulse and a sharp negative spike at the end of the pulse.

So my next thought is some sort of Tesla coil type inductive thing, but I worry that would slow down the pulse and ring.

I guess I may have to think of some active circuit with FETs driven by the same input pulse, but if there is a passive way to do it I would be interested as it might be easier to match the shapes of the positive and negative spikes.

(I looked, but didn't find a similar previous question)

The application is for these two pulses to go onto two separated electrodes for one of two scenarios. 1) to have the pulses go onto plates to generate an electric field so capacitance I estimate as maybe up to 50 pF but probably less - my best guess is 10 pF.  Pulse length of 1 to 10 μs perhaps with close to zero current. 2) to have the pulses go onto two electrodes that are so close together that an arc is formed for a very short time. The arc does not have to be powerful. For arc the pulse length could be as short as 10 ns with a repetition frequency of ~1 kHz and it does not have to be powerful. In fact, given the choice, a weaker arc might be better than a strong one. Again I anticipate a low capacitance of ~10 to 50 pF.


texts: Continuous gate drive for high side mosfet using ir2110

texts:
I plan to provide continuous gate drive for high side mosfet using ir2110. According to ir2110 application  note, a 555 timer is used as charge pump for continuous gate drive but the schematic is hard to understand  and there is little documentation. Plz explain me about this with a schematic..or is there another option for it

The application note link is
http://www.irf.com/technical-info/appnotes/an-978.pdf

My project is on brush PMDC motor position control using PID. The problem I am facing is driving the high side mosfet gate continuously  when required.


texts: Importing transistor spice model to LTSpice not working

texts:
Using LTSpice XVII.  I want to import the Diodes Incorporated ZXTP19020DG model.  The SPICE model from their web site is:

*DIODES_INC_SPICE_MODEL ZXTP19020DG
*SIMULATOR=SIMETRIX
*ORIGIN=DZSL_DPG
*DATE=7/01/2013
*VERSION=1

.MODEL ZXTP19020DG PNP IS=8.5E-13 NF=1 BF=530 VAF=25.8 ISE=1.2E-13
+ IKF=3.8 NE=1.48 BR=130 VAR=5.15 ISC=0.8E-13 NC=1.23 RC=0.0045 RB=0.15
+ RE=0.009 QUASIMOD=1 RCO=0.27 GAMMA=2E-10 CJC=112E-12 MJC=0.4 VJC=0.6
+ CJE=345E-12 MJE=0.53 VJE=0.95 TF=0.59E-9 TR=4.2E-9 TRC1=.003 TRB1=.003
+ TRE1=.003 XTB=1.4

I copy-n-paste the .MODEL stanza into the standard.bjt file. I then open LTSpice and create a new schematic.  I add a PNP transistor, right-click to Pick New Transistor, but the ZXTP19020DG does not show up on the list.

It may seem like I need to tell LTSpice to reload the components — if I erase the 2N2222 and 2N2907 (the first two entries in the original standard.bjt file), the 2N2907 still shows up on the Pick New Transistor dialog (for a PNP transistor).  In all cases, I close and re-open LTSpice after any changes to standard.bjt. I also checked that there is only one standard.bjt file on the whole C: drive (under C:\Program Files\LTC\LTspiceXVII\lib\cmp).

This is what the beginning of the standard.bjt file looks like (I also added the NPN version, ZXTN19020DG, just in case):

* Copyright © 2000 Linear Technology Corporation.   All rights reserved.
*
*
.model ZXTN19020DG NPN IS=9E-13 NF=1 BF=530 IKF=6 VAF=105 ISE=8E-14
+ NE=1.4 NR=1  BR=174 IKR=1 VAR=12.8 ISC=4E-13 NC=1.37 RB=0.17 RE=0.0055
+ RC=0.0035 CJC=89E-12 MJC=0.34 VJC=0.51 CJE=365E-12 MJE=0.39 VJE=0.8
+ TF=9E-10 TR=0.55E-8 XTB=1.4 TRC1=.005 TRB1=.005 TRE1=.005 QUASIMOD=1
+ RCO=0.15 GAMMA=0.3E-9

.model ZXTP19020DG PNP IS=8.5E-13 NF=1 BF=530 VAF=25.8 ISE=1.2E-13
+ IKF=3.8 NE=1.48 BR=130 VAR=5.15 ISC=0.8E-13 NC=1.23 RC=0.0045 RB=0.15
+ RE=0.009 QUASIMOD=1 RCO=0.27 GAMMA=2E-10 CJC=112E-12 MJC=0.4 VJC=0.6
+ CJE=345E-12 MJE=0.53 VJE=0.95 TF=0.59E-9 TR=4.2E-9 TRC1=.003 TRB1=.003
+ TRE1=.003 XTB=1.4

.model 2N2222 NPN(IS=1E-14 VAF=100
+   BF=200 IKF=0.3 XTB=1.5 BR=3
+   CJC=8E-12 CJE=25E-12 TR=100E-9 TF=400E-12
+   ITF=1 VTF=2 XTF=3 RB=10 RC=.3 RE=.2 Vceo=30 Icrating=800m  mfg=NXP)

.model 2N2907 PNP(IS=1E-14 VAF=120
+   BF=250 IKF=0.3 XTB=1.5 BR=3
+   CJC=8E-12 CJE=30E-12 TR=100E-9 TF=400E-12
+   ITF=1 VTF=2 XTF=3 RB=10 RC=.3 RE=.2 Vceo=40 Icrating=600m mfg=NXP)

etc.

What am I missing or doing wrong?


texts: Which frequency is the best for a 3-speed Motor?

texts:
Sorry I dont know the appropriate terms that should be used in this subject!

I have an inductive motor, it has 3 different speeds (or windings) at 50 Hz:

350 rpm / 700 rpm / 970 rpm

I want to drive it with a VFD.
the speed I want is around 1000 rpm.

When I tested it I found this results (more or less):

350rpm ==> 1000rpm @ 140Hz ~ 4 amps.

700rpm ==> 1000rpm @ 71Hz ~ 4 amps.

970rpm ==> 1000rpm @ 51Hz ~ 7 amps or more.

In all cases to motor runs under a normal load without problems..

My questions are:

1. Which one is the best for the **motor, the VFD and the consumption?

2. Higher frequency doesn't affect the motor?


texts: Conflict Minerals in Electronics: What to look out for as a designer?

texts:
There appears to be a small but steady stream of organisations asking for a statement on conflict minerals on goods supplied by the electronics industry.

As an electronics designer, I would expect that at some stage, my organisation will be asked some sort of statement regarding our own supply chain by some customers.

Whilst I can wholeheartedly state that we do not knowingly procure conflict resources, I am also a user of tantalum capacitors and so the best I can do is seek assurances from various suppliers.

Tantalum is the obvious one. Which other components are also considered "risky" in terms of conflict minerals?  Is there an industry standard strategy and/or standard practice that is recognised or otherwise should be adhered to?


texts: Clock usage in the always block and in the event

texts:
In general, if we are working on a sequential circuit, say a Flip Flop (e.g. D Flip Flop)
The code we write for the always block part is:
 always @(posedge clk or posedge reset)
  begin
    if (reset) begin
      // Asynchronous reset when reset goes high
      q <= 1'b0;
    end else begin
      // Assign D to Q on positive clock edge
      q <= d;
    end
  end

I am confused on the point - Why the line if(clk) is not used/written/introduced before q <= d in our always block.
Motivation:
Posedge transition corresponds to transition from:

0 to 1
x to 1
z to 1
0 to x
0 to z

So, why in most of the sequential codes, we don't confirm that the positive edge of the clock has appeared after the edge transition from low to high.
I've searched the forum for this topic but can't find a specific answer on this. I am a newbie and will appreciate your guidance.


texts:
I made a stair led with 610 leds.
All powered with a ATX psu.
The PSU can`t deliver the 5v for the led stripe so im using for 300 of them a buck driver and for the rest the 5v ATX out.
The Buck is powered over the atx.
Power injection over 4mm2 cable every 1.5m (every stair)
I am using a esp 01 with esp home in junction with home assistant.
For the control of the leds im using this eps led schield:
https://www.aliexpress.com/item/4000089372031.html
The problem is now happening when all of the leds are transitioning in animations. they signal gets corrupted. And i get random flickering while transitions happen. And only while the animations happen. Any idea how to fix it?????
i tried:

soldering the last pin in the row (big nono)
capacitors on the ATX and Buck driver. Nope no change
all grounds are connected
When i try to add the recommended resistor on the beg of the stripe it gets worse...

I am guessing the data lane gets much induction interference when the 600 leds change current draw... When i use the scan animation where you only have like 100 leds on it does not happen.
problem is how to remedy this????
Here the esp home yaml:
power_supply:
  - id: 'led_power_supply'
    pin:
      number: 0
      inverted: true

light:
   - platform: fastled_clockless
     power_supply: led_power_supply
     chipset: WS2812B
     pin: 2
     num_leds: 608
     name: stepenice RGB
     id: sve_stepenice
     rgb_order: GRB
     max_refresh_rate: 2.5ms
     default_transition_length: 1s
     effects:
      - random:
          name: Random Color
          transition_length: 4s
          update_interval: 5s
      - addressable_scan:
          name: Scan Effect
          move_interval: 50ms
          scan_width: 32
      - addressable_twinkle:
          name: Twinkle Effect
          twinkle_probability: 70%
          progress_interval: 8ms
      - addressable_fireworks:
          name: Fireworks Effect
          update_interval: 60ms
          spark_probability: 80%
          use_random_color: true
          fade_out_rate: 130
      - flicker:
          name: Flicker
          alpha: 95%
          intensity: 30%
      - addressable_rainbow:
          name: Rainbow
          speed: 60
          width: 300


texts:
Datasheet

What is diffused diode resistor? (p. 22 in the datasheet)
What does it do and how does it work?
Edit: The only thing I've managed to find on Google is that it's somehow related to ESD protection.
See this link (page number 84 written in the document and 99 in PDF readers)


texts:
I am planning a stackup for 2x Ethernet phys. The chip requires a few different supply voltage levels: I/O Power 3V3 (3 pins) and Analog Supplies: VDD2V5 (2 pins) and VDD1V0 (4 pins). Each pin has both 100nF and 1uF caps. I don't have other signals on the board. The board will have 24V/3V3 iso DC/DC convereter and two LDOs 3V3/2V5 and 3V3/1V0.
The board is not excessively complicated however I am thinking of a 6-layer stackup because of those different voltages. The phy IC will bo on top layer, power DC/DC and LDOs on the bottom.
The layers:

TopLayer: Ethernet signals
Mid1Layer: GND
Mid2Layer: 2V5
Mid3Layer: 1V1
Mid4Layer: 3V3
BottomLayer: Power traces, GND pours.

My questions are:

Am I not exaggerating with dedicating 3 layers to power? Should I rather have two GND layers (Mid1 and Mid4) and arrange two pours for 2V5 and 1V1 on one layer?

TopLayer: Ethernet signals
Mid1Layer: GND
Mid2Layer: 2V5 + 1V1
Mid3Layer: 3V3
Mid4Layer: GND
BottomLayer: Power traces, GND pours.

...or b) put that second GND layer on top of Ethernet signals (Eth signals moved to Mid1) so they are sandwiched between two GNDs? I would have to put vias then. I am not sure if it is a good idea.

TopLayer: GND
Mid1Layer: Ethernet signals
Mid2Layer: GND
Mid3Layer: 2V5 + 1V1
Mid4Layer: 3V3
BottomLayer: Power traces, GND pours.

Which voltage level plane/pour should be closer to ethernet signal traces? 2V5 or 1V1 or 3V3? Which one is more important to ensure a better integrity of ethernet signals. Maybe 1V1 should be over 2V5 and closer to GND?
Or are there any better ideas?

The phys are 2x DP83867 https://www.ti.com/lit/ds/symlink/dp83867ir.pdf.
I think I could do the whole design in 4 layers but if 6-layer PCB is better then why not. The PCB is very small so price is not a significant decision factor.
Edit (Added):
Thanks for your feedback Marcus and Andy.
I finalized the design with the following 6-layer stackup:

TopLayer: Ethernet signals
Mid1Layer: GND plane
Mid2Layer: Other Signals
Mid3Layer: 3V3 plane
Mid4Layer: GND plane
BottomLayer: Power traces, 2V5 pour, 1V0 pour, GND pours.

2V5 and 1V1 pours on bottom layer let me minimize the number of vias, as power decoupling caps (for the phys) are also on the bottom layer. (Phys are on top layer).
Other signals on Mid2 helped to keep other planes virtually intact.
And I got a second GND plane, which will be placed between 3V3 plane and Bottom Layer.
So I ended up with a pretty classic 6-layer board stackup.


texts: How do I know to choose a first order filter vs a second order filter?

texts:
I have a DC signal coming off of a battery. The Arduino is reading the voltage. The issue is that the voltage signal contains a lot of noise (120hz frequency). I am planning on building a first order low pass filter but how can I know if first order is sufficient. Do i need to build a second order low pass filter?
Note: When looking at the noise, the 120Hz noise has an amplitude 80mV (which is high)

How do you figure out when to use a low pass first order vs second order?


texts:
For a design I am working with a capacitive feedback network. I can't show you the actual network, but I intend this to be a more general question as it should be applicable to any input network.

Imagine an amplifier with a capacitive feedback network. These are generally as the follows:

simulate this circuit – Schematic created using CircuitLab

These have a transfer function $$H(s)=\frac{C_{\text{F}}}{C_{\text{IN}}} \text{  for } s > 0 \\ H(s)=0 \text{   for } s = 0$$

Now, imagine there is a more complex input network, say:

simulate this circuit

I would like to again remind everyone that I am not looking for a solution to this specific network, but a general solution for capacitive input networks.

My intuition tells me that if I can write the input network as an single equivalent input capacitor using thevenin's theorem, I can just plug that equation in the transfer function and know the behavior of the circuit as a whole, without having to start from the an equation for every node and solve this for the circuit (which can get very clumsy if you have a circuit with more than a handfull of nodes).

Is this correct?


texts: What kind of a wire can we use for frequencies up-to 1Mhz and up?

texts:
I have been reading about wires in Wikipedia

What am I doing?

I am reading about wires thinking that I could by my wide knowledge with bunch of reading be capable of creating simple 8-bit or 16-bit CPU

What I know?

Proximity effect and Skin effect effect wires, I know how we can produce these, but I don't understand how they actually construct.

What I want?

I saw many projects on making simple 8-bit CPUs, they use traditional Stranded wires, however, I am not sure what is the frequency of that CPU, but let's say I am trying to make 1Mhz CPU, what kind of cables do I need? Litz wires seem to be used in >500Khz conditions


texts: Why are 65W and 90W common amongst laptop power supplies?

texts:
I have seen Dell 130W, Lenovo 120W, some 230W or 210W gaming laptops, etc. . These are different numbers.

But I have seen both 65W and 90W power supplies from Lenovo (65W 20V 3,25A with rounded DC connector (built 2007) and Lenovo's proprietary rectangular DC connector (built 2015)) and Dell (65W 19,5V 3,34A) and HP (65W 19,5V 3,34A) and Asus (65W 19V 3,43A). A quick internet search suggests that Acer also uses 65W 19V 3,43A known from Asus.I have seen 90W power supplies from  Lenovo (20V) and Dell (19,5V) as well. The other manufacturers have power supplies at that wattage as well, very likely.

The wattage is the same, while the voltages are slightly different. Why that is, that's a different question, but I am not sure, whether it is sufficiently relevant for Electronics.StackExchange.com. If it is, please let me know.

Why are 65W and 90W power supplies common amongst different manufacturers of middle-end laptops?

Why not 60W, 70W instead of 65W? Why not 100W instead of 90W?Manufacturers use different power connectors, yet the same wattage at a very similar voltage.

(There is nothing wrong with 65W and 90W, I am just wondering why different manufacturers share specifically 65W and 90W. If it is an industry standard, how exactly was it specified?)


texts: How to clean up DC power from interference really well? (better than RC)

texts:
I built a case that houses:

A battery pack as UPS with 5v and 12v outputs https://www.amazon.com/gp/product/B07H8F5HYJ
2 audio stereo amps (12v power) https://www.amazon.com/gp/product/B07V42HVYW
A Raspberry Pi (5v power) with 2 stereo usb soundcards https://www.amazon.com/dp/B01N905VOY

Everything is wonderful except for one problem:
There is an enormous amount of interference in the speakers. These noises correlate perfectly with the activity of the Raspberry Pi, and when I power the Pi with a separate 5v power supply all noise is gone.
So I built an RC filter for the 12v that goes to the 2 amps. I put a huge 4 Ohm resistor (https://www.amazon.com/gp/product/B008ML0LE4) with 6 capacitors of all sorts of values (3 chemical, 3 ceramic) and it is better but still unacceptably loud.
Is there a better way to clean up a DC power?
And if I feel lazy, is there a little device I can buy that does that extremely well so I don't need to build one more thing from scratch?


texts: Does placing digital circuitry between the regulators and analog circuitry cause grounding problems?

texts:
I'm designing a mixed-signal PCB and have been using this Maxim guide to help me with layout. The guide has instructed me to avoid making cuts to the PCB and instead think about ground return paths. By placing chips in strategic locations and orienting mixed signal chips properly I can avoid analog and digital return currents from overlapping.

I am aware that having digital ground currents run through analog circuitry will cause noise problems. In other words, the regulators (R), analog circuitry (A), and digital circuitry (D) should not be arranged in series like so: R - A - D.

Is the opposite also true? Is analog circuitry performance compromised if its ground return currents pass through digital circuitry? Using the acronyms above this would be: R - D - A.

I don't think this would cause problems assuming the analog regulator lines are  routed through the perimeter of the PCB to avoid the digital circuitry. Mixed signal chips would be placed in between the two regions with the digital and analog sides of each chip facing the corresponding direction. Is this true? Or will I still run into noise issues?

EDIT: it looks like the guide I linked to already answers this question:

  Therefore, if the analog and digital return currents (or any two
  currents) share a portion of the ground plane (i.e., their currents
  flow through the same metal) there will be crosstalk between the two
  as the copper resistance causes IR voltage drops.

This indicates that both approaches (R - A - D and R - D - A) are faulty and the circuitry must be laid out in parallel rather than sequentially to avoid this issue.

I will submit this as an answer unless someone has a better explanation.


texts:
The problem:Complete the transformer wiring diagrams according to the Delta primary and Wye secondary configuration.  The secondary will be configured for High voltage.  Connect all loads as needed.
This is my solution:

The problem: Complete the transformer wiring diagrams according to the Wye primary and Wye secondary configuration.  The secondary will be configured for Low voltage.  Connect all loads as needed.
My solution:

I put the red and blue connections. I did not get any information on the voltage or kW. The question is: Did i wire the diagram correctly given the problem?


texts: KCL on source-free RC circuit - confused about current direction

texts:
See here:

Shouldn't it be a decaying exponential?
In Sadiku's Fundamentals of Electric Circuits, he defines both iC and iR as going out of the node, so that ic+ir = 0 ==> ic = -ir. That's how he makes the negative t appear. It's not very intuitive.

Shouldn't the math work itself out and give me the same expression independently of the current direction I assumed?

Is there any systematic way of defining currents and applying KCL without ever running into these sort of problems?

Thank you.


texts:
I am primarily software. I do debug and test a lot of hardware, so I know enough to be dangerous.

Twenty years ago we built Panasonic-compatible analog-signalling PCBs for controlling Panasonic's line of "hybrid" telephones.

What I remember was that it provided power and signalling over a single pair, much line a telephone line itself if you consider the audio to be the signalling.

I would like to reproduce this configuration with the following specifications: the signalling will be a continuous 50% duty-cycle clock with a possible range of 5 to 20 MHz, the DC supply would be in the range of 9V to 24V, with a maximum of 600ma at 5V needing to be produced at the far end (using a SimpleSwitcher). This would be using a twisted-pair ethernet-style cable.

I was thinking there are probably 10 different ways to accomplish this, and numerous what-ifs are swirling around in my head. But since I've little experience in the analog possibilities, I thought I might ask some experts.

Any suggestions would be appreciated. My main goals are: cheap, simple, hand-solderable, and minimum PCB real estate.

Thanks in advance.


texts: Why are non-contact voltage detectors sensitive to vibration?

texts:
I have noticed that if I slap a non-contact voltage detector against my palm, the LED blinks. I have tried this with four six different detectors, each a different brand, and each clearly a different implementation. (And no, none of them appeared to share an ODM.)

Why is this?

I bought a cheap NCVD that exhibits this behavior, and reverse engineered this schematic:

Here's a picture of the PCB inside:

As you can see, the lead of the resistor I am calling R2 extends into the tip of the probe. I initially thought this acted as an inductive pickup, but if you look at pictures of competing devices, you'll see that others use a solid plate here. It is more likely that this is acting as one plate of a capacitor.

The rest of the circuit looks like a fairly straightforward signal conditioning sort of thing. The main IC is a 74HC14 hex Schmitt inverter in SO-14.

I don't think I'm seeing a piezoelectric effect here. The three capacitors are ceramic, and so subject to these effects, but none of the three really strikes me as likely:

C1 is a bypass cap. Its ends are pinned by the power supply, and in any case tiny voltages applied across the 74HC14 power pins don't explain this.
C2 is tied on one side to a low impedance output, and the other to a voltage rail through the big R4 pull-up resistor. I would think either of these would eat any tiny piezoelectric voltages produced.
C3 might be capable of something like this, but I think the next point explains why it isn't responsible.

Once I had the PCB out of the "pen," I soldered some hookup wires to it so I could power it from my bench supply, then tried to reproduce the effect, and failed. I tried smacking the PCB against my work bench, holding on to the hookup wires you can see, working it like a lash. I have also tried smacking it with a toothpick, bending it like the arm of a crude catapult and letting it go so that my hand never touches the PCB.

Later, at Phil Frost's request, I repeated those tests using a 2×AAA battery holder, soldered to the board with 1 foot hookup wires, so I can strike the PCB and battery independently. The effect failed to recur in this configuration: neither battery contact bounce nor PCB vibration seem to be the cause for this effect.

The effect is not due purely to the tester being held by a human. If you take a tester subject to the effect and drop it onto an insulated surface, it still happens. If you don't mind risking your tester in the name of Science, drop it from a foot or so, and you will see that the light doesn't blink until impact. The effect isn't caused by the human letting go of the tester.

I can only conclude that there is something about the physical realization of the final product that causes the effect. For one thing, the plastic housing over the probe tip will modify the capacitance, since it will have a higher relative permittivity than air.


texts: What is the welding technique heater manufacturers use to connect nichrome wire to copper terminals

texts:
I have made hundreds of very reliable nichrome to copper connections using a torch and silver solder (brazing).

Due to the high cost of silver I would like to investigate the welding process that heater manufacturers use. I would like to know specifically how they do it.

If one could supply actual equipment model numbers that would be appreciated. I know that toaster manufacturers just crimp, but that is not reliable enough for my product. A bad connection there just means an inconvenience. A bad connection in my product means destruction.


texts: Different JTAG debug options for ATmega1281

texts:
Background:

I've inherited my first ATMEL project.  It's using an ATmega128A, coded in AVR Studio 4, with the Olimex AVR-JTAG-USB debugger.  I've learned how to use these tools, although I'm still much more comfortable with PICs, MPLAB, and an ICD3.

I upgraded the design to an ATmega1281, which is a pin-compatible version with more horsepower.  Now that the boards are assembled I realize that the new ATmega chip isn't supported by my debugger, and i need to get another debugger ASAP.

I'm looking at ATMEL's current selection of debuggers that are listed as compatible for this chip.  There are five of them, although I've narrowed it down to these three: the ATMEL-ICE ($85), the JTAGICE3 ($99), and the JTAGICE-mkII ($399).

My question:

These all seem very similar!  Are there any red flags here?  I need to stay with AVR Studio 4, I need to do JTAG debugging on the actual target board.  The rest is icing.  Is there a strong reason to choose one over the others?

Thanks.


texts: I just started hearing this term in the context of an arc or sparking between components.  Can anyone define dead metal?


texts: Why isn't the switches being bypassed in this triac/diac circuit?

texts:
Just when you think you understand circuits, there's always a curve ball to derail you and leave you scratching your head.

The diagram below is a Triac/Diac speed controller for a reciprocating saw. At the top of the diagram, you'll notice there is a black wire from the right brush of the motor, a yellow wire to a resistor switch and a white wire connected to neutral.  They are pigtailed together.

Although the diagram appears to be correct and works, I am confused as to why it works. If electricity chooses the path of least resistance, shouldn't the current leaving the black wire go directly through the white wire and back to neutral? Shouldn't it bypass the speed and trigger switches?

What adds insult to injury is that current bypasses the resistor in the speed switch when it is closed. Why does it bypass in. this case and not the other?


texts: What happens to the voltage across an inductor as the frequency increases?

texts:
My professor told us before that when DC is passed through an inductor and reaches t = infinity the element becomes open. How does this happen?

By the way: the inductor has no charge at t = 0s.


texts:
I've found a handful of these strange things in a stock of new old stock components, in the middle of capacitors, resistors, old potentiometer knobs and such lovely surplus cheap stuff.

They measure 1" x 0.5" each and they seems to be mainly made of white ceramic. I've found only these variants (green with two pads and blue with three).
The surface of the pads is conductive.

The other side is white ceramic with no visible features. It seems that the entire content is 'printed' on this side only. No ID or other information are printed, or engraved, or whatever.

The visible snakey "path" between the pads (protected by the colored paint) suggests that some sort of current should flow between them, but the DC resistance between the pads seems to infinite (or at least > 2MOhm), even between the closest pads in the blue one.
I've even tried to apply 12V DC tension with both polarity, but no current flows.

The shape of the 'circuit' in it suggests some form of inductance (HF antenna?), and the blue one seems to be a variant with a tap closer to the top pad (like a transformer). But shouldn't inductors be still conductive at DC level? The same if they should be fuses or other current/voltage protection device.

I haven't tested capacitance but I don't expect them to be capacitors... or not?

Random googling hadn't helped much. I've never seen something like this before and I'm really puzzled now!


texts: Does anyone know what this SMD IC labelled "HuANA" is? I'm having a hard time finding its datasheet on the internet

texts: I am troubleshooting a Xiaomi M365 e-scooter. After checking for problems in the dashboard, I found the BLE controller's supply pin is grounded/shorted with the ground. I found this SMD IC "HuANA" causing the problem.  It is faulty. I want to replace or look for alternative, but I can't find any info on it on the internet. Please help me identify what IC this is.


texts:
I am using the following circuit to convert 230V AC into 12V and 3.3V DC.Here i am using a X rated capacitor instead of a transformer and i am taking 12V and 3.3V DC output from this circuit to power my loads.The circuit is build on a PCB and the PCB is properly covered in order to avoid direct electric contact to the mains through the circuit.Now the circuit is working fine.

But when i continuously power the circuit that is on and off the 230V AC input, some times the resistor R2(22ohm 1W) get damaged.I think the problem is due to the inrush current at the time of power on.

So please let me know that is this problem is due to inrush?
Is there any other reason for this?
If this is due to inrush what will be the suitable value for resistor to protect it from damage due to inrush?
How can i calculate the inrush current in this circuit?


texts: Output impedance of the current output DAC

texts:
As known there are two types DAC using R-2R ladder. One is voltage output and another is current output. The voltage output type has a constant output impedance which equal to R. The current output type has a input code dependent output impedance. Then how the output impedance dependent on the input code? Are there a mathematical function, such as $$R_{out} = f(n)$$ in which n is the input code,  to show this?

Refs:

http://www.analog.com/media/en/training-seminars/tutorials/MT-015.pdf
https://en.wikipedia.org/wiki/Resistor_ladder


texts: Voltage surge suppression technique in high-speed switching based electronic circuit

texts:
I am working on a circuit that transmits ~1MHz sine wave(20V amplitude) in RLC based circuit scheme, also transmits high-frequency signals(pulses(non-periodic)) ~20MHz(10 %DS)(20V) in a CR-based circuit scheme. The circuit involves 'disabling' of inductor for ~20MHz signal transmission for a short amount of time(say 10% of the enabled time).
I'm having problems in suppressing the voltage spikes(~ +-100 V) which are generated the moment I disable the inductor AND after I connect the wire, while the rest of the time the circuit behaves alright. NOTE: I'm measuring the differential voltage across Resistor(275ohm)

XFG3: 20MHZ, 10%DS +- 20V square wave
XFG2: 1.58MHz(RLC resonant), 50%DS, +- 20V square wave
XFG4,1: 500KHz, 10%DS
Desired output: Maximum power transfer at 275ohms(after rectification, filter) + High-speed data transmission(to be demodulated later from 275ohms)
So, to tackle that, I came up with an idea to temporarily enable the pair of opposite Zener diodes which would act as a voltage limiter(say +-20V) right after the switch S1, but it found to be unsuccessful. I can still see the surges. Also, I've read that Zener has high capacitance, so it won't be effective in a high speed temporarily switching(Note that I want to enable the voltage suppression device momentarily for the initial surge protection(~10ns))

I also have an idea to make my switch kind of a hybrid-relay based, where there will be a state for a very short period of time (just after inductor open-circuit and before connecting the wire) to absorb the surges. But, I'm not getting effective ideas.
I also have heard about MOVs. But I'm not sure about its effectiveness as they also possess capacitance. It's not available in NI Multisim, so I am not sure if it's good.
I need some suggestions/ways to tackle the problem.
NOTE: C1 capacitor is an instrument that is very delicate and it's a must to suppress any kind of spike just before it


texts: Basic help with calculating values for PN2222A LED circuit

texts:
I'm gonna be adding an IR LED to my Arduino Uno and I'm trying to wrap my head around the math used to figure out the exact resistor values needed to use a PN2222A transistor to drive the LED.

I know my LED has a voltage drop of 1.35V and I want to run it at 100mA and that I'll be supplying it with 5V from the Arduino.  What I don't understand is the math for how to figure out the exact voltage drop of the transistor between the collector and emitter.  And I'm also trying to figure out the math used to calculate the required milliamps that have to flow through the base of the transistor in order to fully turn it on (but not waste extra electricity).

I know that there is quite a lot of lee way in which resistors to use and the circuit will still work, but I'm hoping to figure out the math so that I can get as close as possible to using the exactly perfect resistor values.


texts: Synchronise multiple Mega boards to run multiple servo motors

texts:
My friend Jules asks:

  The aim is to get as many servo motor controls as possible - looks like the maximum an Arduino will output is 14?

  Digital I/O Pins54 (of which 14 provide PWM output)

I guess then it becomes a software issue to synchronise multiple Mega boards?
- ie 14 x 14 array using 14 boards


texts: How add delays to everything in Verilog or SystemVerilog outside of .v or .sv file

texts:
All delay documentation I've seen is pretty low level -- add a #5 or whatever and that particular assignment gets a delay.  Use this in a module and instantiate, etc, etc.  There are variations on this theme.

What I'm looking for is a way to assign a delay to each and every combinatorial equation or flip flop assignment, without cluttering up the .v file with # signs, and without having to instantiate tiny submodules to do simple things that can be done in a one-liner.

I want to be able to zoom in on a clock edge and see what comes right before and what comes right after, without everything being exactly at the same time, so I can understand the causality of an event.  I'd like to be able to see combinatorial glitches.  I'm also interested in asynchronous (clockless) circuits, so I'd like to see that stuff doesn't happen in zero time.

And I want to do this without having to go through a synthesis for some particular device.  This doesn't need to be super precise, and I'm not looking for timing violations, eg setup and hold, or anything that is specific to a device or technology.  I just want a generic way to tell the simulator to slow everything down by a little bit just to show that the delay is there.  The delay can be arbitrarily small, but should be visible when I zoom in on the waveform.

Is there a way to add a generic delay to everything from the simulation tool?

Currently I'm using Icarus and Modelsim.

thanks


texts:
I want to understand how the CTR of an opto-coupler is linked with its other parameters, for example its switching speed or time delay between input and output or any other parameter.

I am using opto-couplers to switch digital signals.

For example if I have 2 different opto-couplers, first one has just 10% CTR (min) value while the second one has 1000% CTR (min) values.

So when an opto-coupler has 1000% CTR then what parameter would be compromised in it with respect to another opto-coupler that has just 10% CTR value?

Mainly I am comparing HCPL-0530 and HCPL-6751.

Edit:

Let me explain me question more. First ignore the above two opto-couplers as I can now understand that they are of different types and cannot be compared as such.

Let us say we have two similar type of opto's from same manufacturer and in the same product category/family, say both have simple phototransistor at the output stage and simple LED at input. One of them has higher CTR, say 80% while the other has lower than that say 10% only. What I wanted to understand is that given this much info can I say something about the relative values of some other parameter of these Opto's? Possibly if an opto has higher CTR then its some other parameter will be relatively lower compared to another opto which has lower CTR. So is there any other parameter whose value goes seesaw with CTR
value?


texts:
How would I amplitude modulate the Colpitts oscillator directly?

Can this be done by making Vcc the audio signal and DC offsetting the audio signal in order to get the Colpitts to fundamentally oscillate?


texts: How can I tell if my battery is damaged physically?

texts:
I have boughten a rechargeable battery and a charger a few months ago and when I received it, I briefly hooked it up to a multimeter and shoved it in the back of a drawer to use on another project that I was planning to do a couple days later, but it didn't work out, and I kinda forgot about it.

Fast forward a few months. Today, I checked it again, and then I wanted to see if it would fit inside a small space with a wire. It fit perfectly without the wire, but I had to force it a little to get it into the case. When I pulled it out, I noticed that there were some weird "bumps" running along the long way of the battery, but not perfectly straight. I never looked it that closely, but I would assume I would notice it.

That isn't my question. I don't know if it was manufactured that way, it was damaged during shipping, or if I did it. It is a little late to contact the seller, my fault, of course. Is this just a cosmetic flaw that I don't have to worry about? (I found a different use for the battery, so it's not going to be crammed in there anymore.) Should I buy a new one? Test it? It's kinda weird, and it seems cosmetic (no leaks... yet), but I am reluctant to charge it or use it unless I know it's okay and safe.

Photos:

I don't mind replacing them if necessary, but I want to get this done without waiting for a part to come if I can.

They are AAs; "GTL Li-ion 14500 1200mAh 3.7v."


texts: How does this tone generator circuit work?

texts:
I'm an electronics newbie who just started experimenting with the Snap Circuits style kit and I came across this high-frequency oscillator circuit.
When I put it together, I hear a middle to high frequency sound coming from the speaker. The LEDs also blink in sync with those sounds.
Can anyone please explain how this circuit is producing the oscillation?  More specifically, how does the transistors and capacitor work together to flick the LEDs off and on? I'm looking for an explanation that explains the sequence in which electrons flow from the batteries, fill the capacitor, and turn on the transistors to allow the LEDs to flicker.
In the second diagram below I tried to recreate the diagram based on the (somewhat confusing) snap circuit diagram below it. The first diagram below is a rearrangement of the same circuit into a more conventional layout.
Conventional layout:

simulate this circuit – Schematic created using CircuitLab
Layout based on original circuit:

simulate this circuit
Additional info about the Snap Circuit:
The parts include:

100kΩ Resistor (R5)
WC = Whistle chip. The "whistle chip" can be regarded as a 20 nF capacitor which is capable of being modulated by sound.    Treat it as a 20 nF cap for now.
PNP Transistor
NPN Transistor
Red and Green Light Emitting
Diode (LED)
8Ω 0.5W Speaker
Slide Switch
Battery Holder, which uses 2 (1.5V) type AA batteries
Blue Snap Wires to connect the various components

EDIT:

There is some confusion about what the whistle chip is. I've read that
it's purpose is to act as a capacitor. The instructions said that I
can replace it with a 0.02µF capacitor and the circuit will still
work. I have, and it still works.
The collector from Q1 (PNP) transistor does not connect directly
back to the battery. In other words, position 5D is NOT a connection. It just looks that way because of the diagram.
Sorry, I'm just posting the picture that was already made. The
collector of Q1 goes OVER it and connects directly to the speaker.**
The documentation for this diagram can be found as project 210 on on page 38 of: https://resources.demco.com/electronicsnapcircuitsmanual.pdf

Probably more like this - yellow crossing blue does not touch:

WAS shown like this:


texts: Charging Indicator for any battery (Charge Monitor)

texts:
We see in all today electronic devices like mobile a Visual battery charging indicator,that a graphical Container composed of bars that increases one by one when the battery is charged for long, and decreases one by one when the mobile is used for long time.
I see the same thing laptop in every GUI operating system like windows and Linux.

I am thinking from long long ago , under what logic this works?
How the Program is managed to Monitor the battery.
I made a simple logic based on Amps-hour, that how much time the bar should increase when the battery is in charging mode.??? But that does not work perfectly for me.
Also i read a battery indicator Android application source code of my fried, but the function he used were System Calls based on Andriod Kernel (Linux Kernel).

I need the thing from the scratch....
I need this logic to know............. Because i am working on an Operating system kernel project, which later on will need battery charging monitor.

But the thing i will implement right now is to show just percentage on the Console Screen.
Please give me an idea how i can do it.... Thanks in Advance


texts: Most efficient way to convert from 3.5-4.2V (singe cell LiPo) to stable 3.3V for currents up to 500 mA?

texts:
This question is hypothetical - there is no specific project, I just have an obsession with efficiency.

I use a lot of 3.3V modules, and have a bunch of single-cell LiPo batteries (which are amazing), so I'm wondering what would be the best way to combine the two if I were to make a project that would need to maximize battery usage efficiency. As far as I know, there are two options:

Low dropout linear regulator (LDO) - not easy to find one with a dropout of 0.2V at 500 mA loads, but the bigger problem is that linear regulators turn the extra voltage into heat, making them very inefficient.
Use a boost converter to bring that LiPo voltage to 5V, and then use a switching regulator to bring it down to 3.3V. I haven't found any modules on Ebay or Aliexpress that would do it with combined efficiency above 90%, unfortunately. And it appears that the switching regulators are very inefficient at low current draws, typical ones dropping down to 60% at 50 mA and below.

Are there any other ways? Is it possible to achieve an efficiency of at least 95% for such a small voltage difference?


texts: What is the purpose of the resistor on this MOSFET's drain?

texts: Shown in the schematic below is a typical MOSFET driven by a BJT. I know the purpose of almost everything here, except for R4. I just can't figure out what the resistor on the MOSFET's drain is for Is it some sort of pull-down? And why might it be needed here?


texts:
This is the Buck converter with feedback loop.

source: Fundamentals of Power electronics by Erickson and Maksimovic
In this circuit, Vm is set to be 4V. However, in general, in a converter design, how can we determine the value of Vm? Thanks.


texts:
I have a scenario where my Vin is 12VDC and my (small inductive) load is 7VDC.
I need a voltage regulator that would satisfy following conditions:

if the Vin > 7VDC + Vdropout, then Vout = 7VDC
if Vin < 7VDC + Vdropout, then Vout = Vin.

In other words, I want it not to drop out, but instead to feed whatever lower voltage there is to the load. I.e.:
if Vin == 5.5VDC, then Vout = 5.5VDC (or 5.2Vdc - not important)
I was planning to use UCC283-ADJ, but I can't figure out how to keep regulator open during voltage drop or brownout.


texts:
Making a hot wire foam cutter, Using 24 Swg gauge Nichrome wire.
Resistance of wire is 4.39 Ohm/M. I'm using 5cm so divided the amount of resistance as per cm respectively that would be 0.219 Ohms and did a testing with a multi meter. I'm using a 12 volt 1 amp adapter. Fitted up the whole circuit and powered it up but the Nichrome is not heating up. checked for broken circuit but everything seems to be fine. Can anyone please tell me what I'm doing wrong ?


texts: Can you make a seismograph with an accelerometer?

texts:
Actual seismograph electronics are very expensive. I'm just wondering if a seismograph can be made with a adequately semsitive accelerometer. To be exact I want to bury the accelerometer based seismograph and have it sense footsteps.

So is this possible and what method would you reccommend for my needs and why?


texts:
I have an old laser printer, HP LaserJet 2100, with 2 ports:

a parallel port;
an 8-pin mini-DIN female "LocalTalk port" connector:

I am using a Raspberry Pi as a network print server. The Pi is connected to the parallel port via a USB-to-Parallel cable. Raspberry Pi is powered by a micro-USB connector and cable.

I was thinking of finding or making a DIN8-to-Micro-USB power-only cable.

Does the extra DIN8 port supply (enough) power that can be used to power the Pi?
If so, what would the correct pinout be?


texts: Modelling positive feedback through capacitance to a guarded node driven by imperfect op amp

texts:
On my circuit I am protecting a sensitive node with a guard op amp. However, since the op amp has limited bandwidth, at higher frequency there will be feedback through capacitance between the guard and the node.

I modeled this as the following:

The input is a simple voltage divider , so the frequency response should be flat. However, the op amp (universal op amp in LTSPICE) has a GBW of 10MHz and there is a slight phase shift which feeds back through the capacitor.

In the real world, if I can work out its open loop gain poles/zeros, can I use this to model the circuit in the frequency domain? I want to determine the overall transfer function at the guarded node. Any pointers would be appreciated.


texts:
the goal is to find the gain of the circuit. I don't understand the Vi/Vs part. I know they used voltage divider, but why they included the second term(in Red) in the expression? where does that come from? can anyone elaborate on this please?
Thanks


texts:
module test1(input logic A,B,C,D);
 output reg Y;
 always@(A,B,C,D) begin
  case({A,B,C,D})
    4'b0011: Y<=1;
    4'b0111: Y<=1;
    4'b1100: Y<=1;
    4'b1101: Y<=1;
    4'b1111: Y<=1;
    4'b1110: Y<=1;
    4'b1010: Y<=1;
    default: Y<=0;

  endcase
 end

endmodule

The following code is showing the following error:
------- Error Output --------------
test_bench.v:12: error: port ``y'' is not a port of dut.
1 error(s) during elaboration.

Could I know what is the issue?


texts: Stabilizing plot using root locus method

texts:
"Design a PI controller to stabilize the plant \$ G(s)= 1/(s-1)\$ using only root locus method."
Since there are two variables \$K_p\$ and \$K_i\$ ,i.e. one for proportional and one for integral, How do I even start to plot the root locus as there are 2 variables, then how do I stabilize the overall system. I know that Poles must lie on LHP, that can be solved analytically, but how do I find them from the Root locus only, any ideas? Thank you.


texts:
I want to drive a MOSFET gate with about 10V. I use the following circuit as described in Fig. 4
http://tahmidmc.blogspot.com/2012/12/low-side-mosfet-drive-circuits-and_23.html

Is this okay? How do I choose the correct resistor values?


texts: Why does this seem like a strange way of connecting a bridge circuit to the ADC?

texts:
I was planning to hook up a quarter bridge circuit to the AD7730LBR Analogue to Digital Converter that I bought. I was having a look at a "Load_Cell_Schematic" provided by this webpage (the download link is at the bottom of the webpage) where they connected a load cell to the same chip.

As you can see the Output- terminal of the load cell is going to AINI- and AINI2+ of the ADC while Output+ of the cell is going to AINI+ and AINI2- of the ADC. I was going through the ADC’s datasheet and based on my understanding you can either use AINI+ and AINI- pair or AINI2+ and AINI2- pair of the ADC to connect to the output voltage terminals of a bridge circuit or a load cell.

The diagram at page 40 of the datasheet also supports my understanding and I could not find any diagram supporting the wiring shown in the schematic of the webpage. So any ideas what is going on in the schematic and if yes how does that affect the programming of the AINI pins of the ADC?


texts: What can be the reason for a three phase fused socket to always blow the same fuse?

texts:
I am supplying a 30 kW load through a 3 phase socket. The socket is fused and the same fuse (same phase) is always blowing after a few hours of usage.
What are the possible reasons for a single line fuse blown in a 3 phase system?
EDIT: load is a DC power supply


texts: Measuring wattage to PoE device - how to hook up a multimeter inline?

texts:
I'd like to measure the amount of power drawn by a PoE client device (PD) and would like to hook up a multimeter inline to do so. However, power is supplied to the PoE device over two pairs of wires (i.e. 2 +ve, 2 -ve) instead of the traditional one pair for a DC circuit (e.g. a light bulb powered by a battery has 1 leading to +ve and one leading to -ve). See an example here:
https://duncansonline.ca/FAQs/WhatisPoEModeAModeB.htm

Let's assume I am dealing with Mode-A PoE supply - where would I intervene and connect the multimeter probes in the the Cat5E cable? One suggestion I was given was to not mess around with the Cat5E cable but instead hook up the leads into a PoE injector just before the power is split up into the two pairs of wires. I'd like to refrain from doing this if possible since it is not a safe procedure and because we want to use a particular model of a PoE switch as the PSE (power sourcing equipment).

Note:
- it is not possible to measure power on the client device end. It is a closed box.
- I do have an inline power measurement device (Byte brothers POE1000IL) but it does not show instantaneous values and spikes. We have an expensive multimeter that does measure instantaneous spikes and this is what I would like to use.


texts: My task is to provide a relay/control board that can as quickly as possible switch off the current supply to a 2.5W electromagnet, or more specifically, make the magnet release the objects it's attracting. I can't find conclusive information regarding what would be the best type of relay for that purpose, MOSFET perhaps?


texts: FDTD simulation for beginners using matlab

texts:
My previous posts are as follows:

1.Mitigation of dead zones when applying circular polarized antenna

2.Standing waves modes inside a cavity resonator

3.Visual understanding of EM fields within a rectangular metal container

4.Insight into cavity resonators

5.Multimode cavity resonator

I came across an algorithm called Yee's algorithm that uses a finite-difference time-domain to allows me to simulate EM waves. This was exactly what I was looking for. I know there is an abundant source of info already on this platform and on google. However, this is still too complicated for me to understand. In addition, I would like to implement this algorithm using MatLab.

I also know from the previous post of open-source software tools available but once again I have no idea on where to even begin. Can anyone help with regards referring me to a absolute beginners textbook that include matlab code for me to try to gain some form of understanding on FDTD.


texts: RF question: Panel antenna for satellite communication

texts:
Would a "panel antenna" used for RFID (probably microstrip-based; e.g. http://www.joymax.com.tw/index.php?_Page=product&mode=show&cid=2387&pid=364) work for satellite communication, assuming a positive link margin? I can't see any reason why not: there is circular polarisation, directivity, gain, am I missing anything?
(Assume the carrier frequency of interest is within the antenna's bandwidth)


texts: Can a coil gun be made with a boost converter instead of caps?

texts: So I’ve been starting to build a coilgun, and I find most designs either have capacitors or are just really bad. But could a high-voltage boost converter (40000v) and a momentary switch not be used to the same effect as long as you pressed and released the switch very quickly? It would eliminate charge times and be a whole lot cheaper, but I assume there is a reason people have not already done it? I am not very experienced in this field, but from my point of view I think this would work. Can someone who actually knows what they are doing help me out?


texts: How to monitor an Alternator exciter wire with MCU?

texts:
I have a internally regulated vehicle alternator which uses a conventional battery light wired in-between the exciter terminal and positive.

Obviously when the alternator isn't turning the exciter terminal is ground so the bulb is on, when the alternator is turning and charging the terminal becomes live thus no voltage difference and the bulb goes out.

I want to get rid of the bulb and have everything on my engine controlled and monitored with my own MCU.

As the alternator needs to 'see' a current on the exciter terminal I have no option but to replace the bulb with a low value resistor. Nothing above 25Ω works so I'm using a 20Ω resistor. This works and allows the alternator to charge.

I now want to hook up a 3v3 MCU to monitor the state of this circuit and to replace the visual element of the bulb. But it doesn't seem to be as simple as it first seems.

This is a standard alternator circuit:

This is the circuit I've tried:

This allows the alternator to charge and outputs 2.8-3v to the MCU when the alternator is charging, but when is 0.7V when not charging. Obviously I can get the voltage a bit higher by using a 3.3v zener ( I only had a 3v to hand), but how can I get the 0.7 lower. Ive tried putting a pull down resistor in parallel with the zener creating a voltage divider but this affects the 3v when the alternator is charging.

I've also tried using a onto coupler but no matter what value of resistor I use I cannot get the opto to trigger.

It may seem that 0.7 is low enough to register low but I want to make sure that this circuit will work with all alternators. So I need the value to be as low as possible.

What is the best way to monitor the exciter terminal of a alternator with a MCU?


texts: Calculation of transmission loss of a power plant

texts:
What is the transmission loss due to heat if my power station produces electricity at a power of \$5 kW\$ and the electricity consumer is \$1 km\$ away?

It is a copper line with a material constant of \$0.017\Omega \frac{mm^2}{m}\$, a voltage of \$1kV\$ and a cross-section of \$10mm^2\$.

My approach, which I don't know if it's true or not, is as follows:
$$I_{cable} = \frac{P_{generated}}{U_{grid}} = \frac{5kW}{1kV} = 5A$$
$$R_{cable} = \rho * \frac{l}{A} = 0.017\Omega \frac{mm^2}{m} * \frac{1000m}{10mm^2} = 1.7\Omega$$
$$P_{loss} = (I_{cable}^2R_{cable})* 2 = 85W$$
So that of the \$5000W\$ produced about \$5000W - 85W = 4915W\$ can be consumed.

Is the calculation so possible? If not, then how?


texts: Could we theoretically massively increase number of parallel computations (for some problems) by getting rid of cpu clocking?

texts:
CPU clocking involves making sure that each operation or part of an operation takes exactly a certain amount of time (the machine cycle time).

One way to increase the efficiency of a cpu is by introducing pipelining: we cut a basic computation (e.g. floating point multiplication) into parts, and then make sure that each part lasts one machine cycle. If we then have e.g. 5 parts, we can theoretically run 5 instructions simultaneously by having them go through each stage of the pipeline separately.

However, pipelining requires the use of latches, in order to demarcate the stages of the pipeline, and the cpu clock is connected to these latches. This puts an upper bound on the number of computations that can be performed simultaneously: at the very least, there cannot be more stages than the depth of the combinational circuit.

However, my thought is: get rid of clocking altogether, and get rid of the latches. Then simply send each computation “immediately after the other” So the circuit will theoretically be able to do as many computations such that signals immediately sent after each other are still distinguishable.

I know that this has many practical problems:

writing the results to memory will be a bottleneck (i think)
timing the computations is difficult.

Nevertheless, I am wondering whether such a proposal has any hope of ever being implemented? Have people worked on this already?


texts: Problem with dual channel back-to-back mosfet AC dimmer

texts:
I'm having a problem with a two channel mosfet dimmer that I'm constructing. When I had only one channel (T1_signal and Load_1_Live) populated on the PCB in the schematic below the dimmer works fine. But when using two channels they interfere with one another. If channel 1 is fully on and channel 2 fully off then channel 2 turns on during the top half of the AC sinewave. The reverse is also true (if you swap places with 1 and 2 in the previous sentence).

Below the schematic is another example where channel 1 on the dimmer is set to about 20% intensity (mosfets on for about 2ms). In the first scope image channel 2 on the dimmer is set to 100% intensity (mosfets always on). Magenta (3) on the scope is measured at the drain of Q1 and cyan (2) is the T1_signal. As seen the top half of the sinewave does not get dimmed/chopped to 20%/2ms. The second scope image shows the same scenario except with the intensity of channel 2 on the dimmer set to less than 20% (mosfet on time for channel 2 less than the 2ms on time for channel 1) and now the upper half of the sinewave gets correctly dimmed.

I tried putting a diode between R9 and GNDA, thinking the problem had something to do with current moving from the gate of the mosfets that are on to the gate of the mosfets that should be off thus turning them on, but that didn't change anything.
Can anyone figure out what is going on here?

Thanks in advance,
Lars E


texts:
Active antenna amplifies received signals with active components, so it has better parameters. Active antenna for the only receiving systems like GPS and TV signals are exist on the shelves. But the active antenna for two way communication systems like GSM/GPRS devices are rarely or even non exist. It seems designing such these antennas are possible with separate parts for receiving and transmitting, but practically does it exist any active antennas for GSM communication?

I need to improve GSM/GPRS signaling for a M2M system in poor signal quality environment, so I need some recommendation for this purpose.


texts: What's the easiest way to solder TSSOP parts?

texts:
I'm limited by DIP so I want to branch out but my hand is shaky as it is with DIP so I can't even imagine trying to solder TSSOP. Are there easy methods for this? Do I need better equipment? I heard of some cooking method?

Found this which looks way too easy: https://www.youtube.com/watch?v=5uiroWBkdFY

What's going on here, what's that paste and is it that easy?


texts: How to have an Arduino wait until it receives data over serial?

texts:
So I've wired up a little robot with a sound shield and some sensors. I'm trying to write a sketch that will let check the sensors.

What I'd like for it to do is print out a little menu over serial, wait until the user sends a selection, jump to the function that matches their selection, then (once the function is done) jump back and print the menu again. Here's what I've written, but I'm not a that good of a coder, so it doesn't work. Where am I going wrong?

#include <Servo.h>
Servo steering;
Servo throttle;
int pos = 0;
int val = 0;
void setup(){
  Serial.begin(9600);
  throttle.write(90);
  steering.write(90);
  pinMode(A0, INPUT);
  pinMode(7, INPUT);
  char ch = 0;
}
void loop(){
  Serial.println("Menu");
  Serial.println("--------------------");
  Serial.println("1. Motion Readout");
  Serial.println("2. Distance Readout");
  Serial.println("3. SD Directory Listing");
  Serial.println("4. Sound Test");
  Serial.println("5. Car Test");
  Serial.println("--------------------");
  Serial.println("Type the number and press enter");
  while(char ch = 0){
  ch = Serial.read();}
  char ch;
  switch(ch)
  {
    case '1':
    motion();
  }
   ch = 0;
}
//menu over, lets get to work.
void motion(){
  Serial.println("Haha, it works!");
}

I'm pretty sure a While loop is the right thing to do, but I'm probably implementing it wrong. Can anyone shed some light on this?


texts: Calibrate without a known good voltage source

texts:
I'm traveling and don't have a known exact voltage source. I do have a variety of electronic components such as resistors of various flavors and am wondering if there is some kind of trick to getting a known voltage value against which I could calibrate a DMM ( which would in turn allow me to calibtate all sorts of other stuff).

Any ideas welcome!


texts: Using a single channel on a 2 channel DAC + Amplifier

texts:
I am planning to use an external DAC + amplifier combo to output mono sound from my microcontoller. The ouput from the amplifier would be connected to a single speaker

DAC : PCM5102
AMPLIFIER : PAM8019

The sound data from my mcu is MONO format and both these chips support 2 channels.The I2S data will be mono.

My question is how do I just use the single channel on them? What do I do with the OUTL pin (on PCM5102) and LIN, LOUT-P and LOUT-P pins(n PAM8019)? Do I simply connect them to ground?

I've never worked with audio before so all this is new to me.

Thanks for the help!


texts:
This figure shows an ADC.
My question: Why there is resistor (R) connecting to inverting pin of each OPAMP.
Are they really necessary? In my opinion, they can be removed because you will have to compare the
voltage at non-inverting pin to the voltage at inverting pin anyway. And that is enough for converting
analog Vin to digital signal.
So what's the point for having those resistors?


texts: How should I power my permanentified project?

texts:
I have transferred my project from an Arduino to a microcontroller. I want to make it into a permanent installation; for that I need to power it.

If I want to power it via a wallwart, what precaustions/safety circuits should I add? How about with a battery?

If I had a choice, which would be more advisable?


texts: How can I improve conducted emission caused by a bad primary electrolytic capacitor?

texts:
I recently got the job to find out how to pass conducted EMI tests with a bad electrolytic capacitor after the rectifier in a power supply. The background is of course, that the new type is cheaper than the one used at the moment (with which the product complies to all standards). I have some experience with radiated emission of a PMSM-driver or a step-down converter but nothing so close to mains. In which way shall I make my investigations?

I should add b.t.w. that the layout of the PCB must not be touched at all.


texts: Waveform for one byte sent over 3.3 V TTL

texts:
I have this question in my lab which I am not able to solve. It would be really appreciated if I could get some help with this.

The question is: I need to draw the waveform for 1 byte sent over 3.3 V TTL.

I have seen the waveform for this on the RS-232. I was wondering if someone could tell me how the 3.3 V TTL one will differ from the RS232 one.

This is the exact question I have:

  You will be using an oscilloscope to investigate serial port of the Raspberry Pi. One standard for serial communications is RS-232, but the port we will use is 3.3V TTL.

  Draw the waveform you would expect for one byte sent over this serial link.


texts:
I am trying to create an IP using Vivado HLS. I have a lot of arrays. I have given directives to infer BRAM, with my array bram_arr like

#pragma HLS_RESOURCE variable=bram_arr core=RAM_1P_BRAM
set_directive_interface -mode bram "bram_init" bram_arr

Still I don't get a BRAM.

What should I do to infer BRAM for the array bram_arr?


texts: Circuit to connect/disconnect a battery from circuit input, controlled by the MCU, self-power-off

texts:
Here is my current idea, but I'm wanting something better. Because in my circuit it is missing a way to discharge the capacitor C1 whenever the battery is disconnected from the circuit input. I have used a high-side switch with P-mosfet but it can be used low-side switch instead.

The baterry will not be connected to circuit input (VIN) constantly, it can be connected/disconnected to/from the circuit input.
When the battery be connected to VIN/circuit, I want VOUT to be connected to VIN initially, then the MCU will turn on and will imediatelly put one digital output to level '1' to guarantee that VOUT stay connected to VIN. Then the MCU will do its job (processing) in some seconds and after finished, the MCU will put the same digital output to '0' in order VOUT disconnects from VIN in order there will be only a few microAmps of consumption from the battery. If the battery be disconnected from the circuit and connected again, the process above should repeat.
That is, if the MCU can do its job/processing in 10 seconds, but the battery was connected for a period of 60 seconds, there should be power consumption from the battery only for 10 seconds and not 60, because after 10 seconds the MCU will disable its own power (and power of the whole remaining circuit connected to Vout).

How to do such control with minimal parts? Is there specific ICs to do such job?

Consumption at Vout = 300mA MAX. After Vout comes a buck-boost switching regulator that will generate an stable 3.3V rail from the Li-Ion battery voltage range.

Regards.

EDIT (1):

At VOUT there is connected a buck-boost switching regulator TPS63001, which has fixed 3.3V output voltage. Page 1 of its datasheet shows "Device Quiescent Current less than 50 μA".
VIH of EN pin = 1.2V minimum. If I do control EN pin from the MCU, how would look the circuit? I will need a capacitor anyway, correct? Not just a pull-up.

Datasheet link: http://www.ti.com/lit/ds/symlink/tps63001.pdf

EDIT (2):

Checking again the datasheet of TPS63001, it shows that the "Shutdown current" is 1uA at maximum.

EDIT (3):

I have decided that I will control the EN pin of TPS63001 with the MCU and by using passive components. Below is my circuit proposal to control the EN pin:

Consumption of resistors when VBAT = 3.7V:
I = 3.7V / 100K+3300K
I(uA) = 3.7/3400 * 1000
I(uA) = 1.088uA
T = 0.1uF * 3300K
T = (0.1*10^-6) * (3300*10^3)
T = 0.33s
3T = 1s

I think there should be no considerable delay between EN be recognized as level 1 and the 3.3V output rail of TPS63001 be stable and the MCU powered on. The first thing the MCU will do is to place the digital output to level 1.


texts: Standalone STM32F030CC minimal configuration

texts:
I'm making a PCB with the STM32F030CC microcontroller and have been reading up on the minimal configuration in the datasheet. They don't include a minimal setup diagram, but I found some information on how to connect the power with filter capacitors.

I will be using all 6 UARTs, but nothing else. Do I need to have the ADC filter capacitors as I won't be using the ADC?

Is there anything essential for it to work that I have missed? I will be using the internal oscillator, so I won't need any external crystal.


texts: Arduino ADC values change after USB disconnect

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I using an Arduino uno analog read function to read a voltage divider circuit for a voltage range from 0-70 VDC. On the voltage divider, I am using 2.7Kohm and 36kohm to reduce to voltage range from 0-70VDC to 0-5VDC for arduino analog input.
The circuit works fine with the USB power to the arduino, and as soon as the I disconnect the USB, and the arduino switches to the backup dual switching power supply (120 VAC to 12VDC and 5VDC), the analog values change.
The values are still steady and I dont see any garbage values, but there is a big offset between the original values and the values after disconnecting the USB power to arduino.
Can anyone comment with a solution to this? I checked multiple times and the ground is common through out the circuit.


texts: Getting MCLR error in Proteus on PIC18 in a really simple circuit

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I'm simulating this circuit below in Proteus 8.1. It basically consists of a switch that, when pressed should send a signal to port A, and then port B should light a LED.

I am using PIC18F4550, and the exact error I am getting is: $MCLR$ is low processor is in reset.

How can I solve this?


texts: How easy it is to order bulk customized .NET MicroFramework compatible boards from China?

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I'm starting developing .NET MicroFramework with Netduino. My softwares are not rebotic oriented, they are mostly related to reproducing video and related stuff. (I know that in order to reproduce video I'll need more powerful processors then Netduino but I'm using it to study now).

But one thing that keeps in my mind is: If I'm able to develop great software that aggregates value to the hardware and I manage to create a product, how can I make it commercially viable? I cant ship Netduino microcontrollers within my products due to possible licence issues and most of all: Price.

I'd need to order a company to produce and assembly boards for me, and I would then insert my software and distribute it. I guess the perfect place for this company to be in the world is China.

The problem is: How feasible is this? If I design a board, there wil be a company able to build for me for an affordable price? How much cheaper will it be than a third party Netduino board?

Thank you so much for any insight


texts: Connecting a three phase drive - Should N connect with L3?

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I have a simple question. I'm going to connect a three phase motor.
'Three phase source -> drive unit - > three phase motor'
But between the three phase source, should I connect N with L3, or should I ignore the N line?
The drive's brand is VLT Micro Drive FC 51 Danfoss


texts: Offset Error Changing after Calibration of Output

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I have a circuit (shown in figure 1) that is supposed to function as a precision analog output. It outputs a DC voltage in the range of either ±10V or ±5V, depending on which gain resistors are used. This analog voltage is intended for use as a reference type of voltage, entailing:

High Accuracy ±(0.1% + 1mV): after calibration
~5-10mA of output current maximum
DC output, no transient slewing specifications formally stated

Figure 1: circuit in question.

For +/-5V output the gain is \$G=1+\dfrac{R_1}{R_2}=2\$

For +/-10V output the gain is \$G=1+\dfrac{R_3}{R_4}=4.026\$

Output is \$G\cdot(V_{DAC}-2.5V)\$

After a calibration, the output of the circuit performs to spec. The calibration I used is a simple slope and offset error correcting equation that operates on the code I send to a DAC, shown the code below.

voltage = 5.0;                         // set voltage

cal = (voltage * 1.0047) + 0.0144;     // slope and offset calibration
value = ((cal + 5) * (65535 / 10));    // translate -5 – 5 –> 0–5

if (value > 65535)                     // send max output if value > 2^16
{
    value = 65535;
}

output_MAX5134(value, AO_DAC_0);       // write to DAC output 0

The problem is, if I come back the next day after calibration, there will be an offset present on the output. The gain error is still eliminated, but I will see something like 2.5200V instead of 2.5005V. The  thing I can think of is the temperature is effecting things, maybe I have to account for it?

For reference I am using:

1% Tolerance SMD resistors -> should be accounted for in calibration

REF3425 -> 0.05% 2.5V Reference
http://www.ti.com/lit/ds/symlink/ref3425.pdf

INA145 -> Difference amplifier as Unipolar to bipolar converter
http://www.ti.com/lit/ds/symlink/ina145.pdf

MAX5134 -> 16-bit DAC with high linearity
https://datasheets.maximintegrated.com/en/ds/MAX5134-MAX5137.pdf

I am using a u3606A  5-1/2 digit multimeter for voltage measurements

INA145 Gain Error Vs Temp:

INA145 Offset Voltage Drift Vs Temp:


texts: I2S interface ideas for multiple MEMS microphones

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I plan on forming a microphone array with 4 MEMS microphones and doing the signal processing(beamforming) in matlab/C on my PC.

MEMS mics i use have Digital I²S interface with high precision 24 bit data (ADMP441). I have them placed on the PCB so they are ready to use.

I can't directly connect these mics to my PC so i need an interface between the mics and my PC however however i don't want to spend too much effort into this step and keep it as "high-level" as possible since i am pretty incompetent on hardware level. I currently may have access to an FPGA board (Nexys2/spartan3E) or a raspberry pi.

Handling I2S input on raspberry pi by programming in C doesn't sound much scary i suppose but i don't know where to even start on the fpga board. As in: which pins to get the input from or how to adjust the clock frequency so that it can handle 4 I2S inputs. I have basic verilog knowledge and probably enough digital electronics knowledge.

If this is managable with the FPGA without any additional interface circuitry, i would like to get into "how".

I have read similar questions but none of them provided basic guidance to my problems.

Thanks in advance!


texts: Can my PID controller have negative p value and positive i value for a PID logic

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I am building my first PID controller.

My process variable and my actuator value are inversly related, meaning if actuator value increases process variable decreases, and vice versa.

So I have tried with a negative value of P and positive value of I.

It works fine for a while and then process variable keeps increasing with actuator  becoming as 0.

Can some one help me with what might be the reason for this? Is it okay to have P as negative and I as postive?


texts:
I've been successfully using the USI on an Attiny84 to talk SPI to a radio module. This is good for hacking up sensors and whatnot as little radio devices. My next sensor project involves a sensor with an I2C interface. I know the USI can talk I2C as well, but I'm already using it to talk SPI to the radio.

I know the USI itself has mode bits to switch it from three- to two-wire mode, so I could have it talk SPI or I2C. But how might this interact with external hardware? When it's in I2C mode to talk to the other device, the SPI device's SS line is deasserted, so the SPI radio will just ignore it. But when it's in SPI mode to talk to the radio module, surely the data and clock lines will be such that the I2C device thinks a transaction is ongoing? Anything I can do to prevent this?

Some ideas I have:

Software implementation of I2C on two spare GPIO pins.
Putting a buffer gate between the clock output of the tiny USI and the SCL line of the I2C bus, so that one GPIO pin on the tiny can control it.
Use another GPIO pin as the SCL line on I2C bus, and use software-only clocking of the USI.

Each of these uses at least one other GPIO pin though, and I don't have many spare. Can I do it a nicer way? E.g. some order-guaranteed way of working the lines when in SPI mode, so that I2C never sees a "START" condition?

Has anyone else ever successfully mixed these?


texts: Why are the semiconductor chips (DRAM) volatile

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Let me clarify, we all know Dynamic RAM is volatile in nature (it just won't hold data when it's turned off).

I've been searching throughly about why instead of the 'what' about it, I just can't find a technical reason about why it won't hold permanent data.

I would like to know 'why' it doesn't hold permanent data (technically).


texts: Will there be a capacitance in a wound coil?

texts: A wound coil in general is a series LR circuit. If the coil has N turns, will there be a capacitance in between consecutive turns of the coil? If there is a capacitance, is it parallel to L and R or is it parallel to L? Also what will be the range of this capacitance?