texts: What is the purpose of a resistor on the non-inverting terminal of an Op-Amp Integrator?

texts: I have seen this type of circuit design a few times, but am not sure why it is needed. Considering the schematic below, what is the purpose of resistor R3?


texts: Eagle Schematic help for 74AHCT125 quad level shifter

texts:
I have an Adafruit Quad level shifter 74AHCT125  that I am trying to build into an Eagle Schematic and PCB for a project.  I am very new to schematics as in...this is my first attempt.  I piggybacked on a GitHub issue that defines out more of the issue with additional images and links.

Essentially when I add the 74*125 part to the schematic it just drops in a single transistor for each click that is performed. I believe these represent each of the quad level shifter as it labels A, B, C, D for each one.

I am looking for advice and guidance on how this should be wired in the schematic.  I am also baffled how there are so many connections to the packages but I only use 1 level shifter and the transistor schematic only has 3 connection points.

Fritzing of the setup (blue is GPIO18):

Current setup of schematic...pretty bare.


texts: When I look some multimeter manuals it says stuff like "0,2% +5", and in videos I hear this as "0,2% plus 5 digits"...but what does it mean in practice? What is this +5 saying?


texts: Converting Battery Operated Motion Sensor Light to AC Powered

texts:
I have converted many battery powered devices to AC adapter in the past.  This time around I am using a Motion Sensor light which takes 4 C batteries and is used to light a closet.

When I connect a 6V, 1 amp adapter to it, it does work but errantly. If it is off and motion occurs it does turn on but other than that it has a mind of its own. It will stay on for hours at a time or turn off for a while and then turn back on with no outside influence.

I am starting to think that somehow the adapter is affecting the sensors in it. By no means am I an expert in electronics and would appreciate any suggestions. My best guess is maybe I need to filter the supply coming into the light somehow.

Below is the product I am using.

Mr Beams® Wireless Motion Sensor LED Ceiling Light MB980

Here is the adapter I am using, the 5V version. I was using a 6V before, both yield the same results.


texts: Confusion on pop for recursive assembly code

texts:
I'm confused on what happens during POP. When POP LR happens does that change the PC to the location of LR, which would be sumi. If it does take it back to sumi wouldn't that just take the recursion even further?

c++:

int sumi(int n) {
  if(n == 0)
  return 0;
else
  return n+sumi(n-1);
}

assembly:

sumi:
CMP R2,#0 ; n is R2
BNE else

then:
MOV R0,#0 ; result in R0
BX LR

else:
PUSH LR
PUSH R2
SUB R2,R2,#1
BL sumi
POP R2
ADD R0,R2,R0
POP LR
BX LR


texts: AC regime: Serial connection of ideal current generator and impedance and Parallel connection of ideal voltage source and impedance

texts:
I have the following two scenarios in the AC regime:

Serial connection of ideal current generator and impedance

Parallel connection of ideal voltage source and impedance

When we have the first scenario in a circuit, and we are using one of the methods (Potential of nodes method, Method of contour currents), to find potentials and currents, do we change the serial connection of ideal current generator and impedance by only with ideal current generator? In other words, does the first scenario becomes (Z is annulled):

?

But, if are asked to find, for example, active power over impedance Z, we can't annulle it.

How do we know when to annulle Z and when not to?

What happens in the second scenario?


texts: Clock divider circuit with flip D flip flop

texts:
I am using D flip flops in my clock divider circuit. I have started with one FF and moving up with the number of divisions I want to have in my clock. This is how I want my D ffs to work.

Now I have my Verilog code for one FF.

   module dff (clk, reset, d, q, qb); // D flip flop one level
   input      clk;
   input      reset;
   input      d;
    output     q;
    output     qb;
    reg        q;
    assign qb = ~q;

    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
  endmodule

and the test bench

    module testbench;
    reg clk_t;
    reg reset_t;
    reg d_t;
    wire q_t;
    wire qb_t;
   // Instantiate design under test
   dff dff(.clk(clk_t), .reset(reset_t), .d(d_t), .q(q_t), .qb(qb_t));
  initial begin
  // Dump waves
  $dumpfile("dump.vcd");
  $dumpvars(1);

  $display("Reset flop.");
  clk_t = 0;
  reset_t = 1;
  d_t = 1'bx;
  display;

  $display("Release reset.");
  d_t = 1;
  reset_t = 0;
  display;

  $display("Toggle clk.");
  clk_t = 1;
  display;

 // Dump waves
 $dumpfile("dump1.vcd");
 $dumpvars(1);

 $display("Reset flop.");
 clk_t = 0;
 reset_t = 1;
 d_t = 1'bx;
 display;

 $display("Release reset.");
 d_t = 1;
 reset_t = 0;
 display;

 $display("Toggle clk.");
 clk_t = 1;
 display;
 end

 task display;
 #5 $display("d_t:%0h, q_t:%0h, qb_t:%0h", d_t, q_t, qb_t);
 endtask

endmodule

and the simulation

When I add the second flip flop with this module:

     module halfclk(clk, reset, d, q, qb); // D flip flop two levels: 1/2 clock
     input clk;
     input reset;
     input d;
     output q;
     output qb;
     wire w1, w2;

     dff dff1(clk, reset, d, q, qb);
     dff dff2(w1, reset, d1, w2, qb1);

    endmodule

and changing the module line in test bench to:

dff halfclk(.clk(clk_t), .reset(reset_t), .d(d_t), .q(q_t), .qb(qb_t));

which I get this:

which is basically the same signal with no change. This is what I want to see:

What am I missing here?


texts: 3 - bit Counter (repeat after each 6 clocks)

texts:
I have tried to make a counter which counts until six clock cycles and then repeats.
And would like to know whether I have done all right and the counter works correct.

simulate this circuit – Schematic created using CircuitLab


texts: What if I switch the place of the load in a common emitter NPN transistor circuit?

texts:
As you can see in the picture, there's an NPN transistor in a common emitter configuration. In the first configuration, the load is placed between the collector pin and Vcc, and it is the most commonly used configuration.

Then, in the second configuration, I moved and put the load between the emitter pin and GND. I have never seen this configuration where the load is at the emitter pin, but both configuration seems to work just the same. I have tested both configuration using some generic NPN BJT transistor as a switch to turn on a load (in this case, an LED). I used 2N2222A, BC547, and the higher power TIP3055).

Is there any advantages or disadvantages between the two configurations? In my opinion, it seems to work just the same way, but I'm not sure because I have never seen the second configuration applied in circuits (or there's any?) I don't know.


texts: Arduino crashes switching 230V relay OFF

texts:
Here is my circuit schematic :

I need to power ON/OFF a 230VAC fan using a relay.
The relay is powered by a 5V DC power supply.
Digital pin on the Arduino board open or close the circuit in PNP as it is HIGH or LOW; If it's HIGH, the relay is switched ON, otherwise it is OFF.
There is also a snubber diode to avoid current from relay induction.

The digital pin is controlled by RX message.

This is working very well when 230V AC is powered OFF,
but when it'is ON the Arduino crashes, and gets unable to receive RX messages.

I think something is wrong in my circuit.
Can you help me please?

Edit

Here is my new schematic : I've removed the transistor and the snubber diode
The digital pin is directly linked to the command pin on the relay with 2.2k resistor and a simple led

RX/TX is still crashing, and the arduino seems to act very slowly


texts:
I was asked to analyze this Op-amp circuit and I need a little bit of advice about it. I have presented my analysis about the circuit, kindly correct me wherever I am going wrong.

simulate this circuit – Schematic created using CircuitLab

If a positive voltage is applied at Vref then the negetive terminal should also necessarily have its voltage at the same.
Hence a current will try to flow through the 100 ohm resistor into the ground, but will be unable to do so, since there is no circuit path. What I don't understand is what will happen in this case, will there be a current flowing through the amp feedback short path?
If the reference voltage is negetive, a current may flow through the emitter, but what will be the voltage at the base? And even if a current flows through the emitter, will the reverse biased LED through the collector allow this.

Hence, I think the circuit is wrong, please give me your suggestions...

P.S. The diode D1 is a laser Diode, I don't know what that implies. Is it different from an LED diode?


texts:
I am trying to use ADS1252 ADC with Arduino. I got following schematic from git of a breakout board for ADS1252

Now there is only one pin dedicated to input signal whereas I want to use this board in differential input mode.

Questions:

Is it possible to use this circuit in differential mode if I give SIG2 to inverting terminal of U2 ?
why is this configuration of OPAMPs used between SIG and ads1252 input pin?


texts: 2S BMS for Li-ion Battery not charging the batteries

texts:
I have been working on a small DIY project. Reference for this project is the following video from YouTube. DIY - 12V Mini UPS
While I was able to put together everything and it works for most part, I see one issue and need some help there.
The device works from the backup perspective. So, when I have power from the mains, the router works on mains but when power goes off, it works on the batteries from this device.
So, when I started, the batteries has full charge so I was getting 8.4 volts out of them. To check the working I turned off the main power. After sometime I checked and as the voltage had dropped to 7.5 volts I switched on the main power. While the router did not have any interruptions due to this, I noticed that the batteries are not getting charged even when I have main power available.
Question - Does this type of BMS charge the batteries? This is one of those cheaper BMS available online through a number of sites and from the description of it I had the impression that it charges the batteries as well.
The actual link from where I bought this BMS is mentioned below. 2S 10A 18650 7.4V-8.4V Lithium Battery Protection Board
Any help will be appreciated.


texts: What would cause a zener shunt regulator to have Vout < Vz?

texts:
I'm restoring a old motorcycle and the headlight is very dim. Upon inspection, there appears to be a shunt regulator. I infer that the part they call the 'regulator' in the diagrams is just a zener diode in parallel with the light bulb. I am basing this on my observation that the regulator has 2 leads which just go between the headlight + terminal and ground. My measurements seem to indicate the series resistance in the shunt regulator is about 1 Ohm.Anyway Vin comes from the magneto and is AC so we would expect the voltage to the headlight to be between Vz and about -.7V.

The light bulb is 6v and 25watts. If I just pull out the 'regulator' (what I think is simply a zener) the light gets bright and the voltage at idle is ~5v and it goes up much higher at higher rpms (>8). With the zener in there, voltage is limited to about 2V (should be 6).

I bought a new zener because it seemed obvious that the current one was permanently conducting too much current. The one I bought was 50W and 6.3V. I tried it and it is barely better! It limits the voltage to about 3V. How is that possible? How can the output voltage actually be lower than the zener voltage? I thought the zener wouldn't even start conducting until we reached the zener voltage, but it appears to be conducting even below the Vz. Is there anything I can do to fix this?


texts: How is this Schottky diode helping discharge the filter capacitor?

texts:
I'm trying to filter the possible bounce of the mechanical switch S1. For a simulation of a sequence of pulses the voltage on C1 keeps adding, it discharges very slow, so after some 10 ms bounces the output signal is activated:

If I place the Schottky diode D1 then it works much better (saw this in some book) but I don't understand why. This is the result:

But anyway the voltage in InputBySW is still increasing, is there a way to improve this?

EDIT:

I guess the effect of the diode is just its leakage current helping discharge the capacitor:

So my question remains, how to decrease the discharge time of the capacitor?


texts:
How to correctly calculate the bandwidth of this amplifier?

My calculations of the second stage filters give me ~3-72 Hz as a result, which is right according to the datasheet. However, when I do AC sweep in LTspice, I get slightly different results:

Why is that?


texts:
I'm working on a system comprised of two boards (power board, screen board) powered either via European outlet (220v 50Hz) or a LiPo battery.

Power handover is achieved via an autoswitching MUX that defaults to the battery when no voltage is coming from the brick PSU.

Fun begins when I plug the AC side, huge overshoot (~2V), and ringing on the main power rail (not regulated, the one that feeds the LDOs) until the PSU stabilizes, that's causing all sorts of un-funny stuff like "pressing buttons" and resetting the microcontroller (ringing gets through the LDOs).

The PSU is a Meanwell IRM-10-5, and even tough it has input filtering the AC side looks like this (fuse is is the mains socket):

AC L - MOV - Xcap - CM choke - PSU

AC N - MOV - Xcap - CM choke - PSU

At the output of the PSU there are a couple hundred mics of LOW ESL tantalum capacitors and from there straight to the power MUX IC and from there to the screen board (350mm unshielded cable).

I've hand soldered a standalone PSU and I can appreciate the same behaviour. The PSU has massive internal capacitance, fast plug/unplug cycles exhibit a very similar response.

My questions:

a) Am I a looser for not testing beforehand the PSU and making sure it had a soft start function and now i'm basically screwed?

b) Have I forgotten something either on the input or the output of the PSU that's upsetting her?

c) Has anyone any tips on how to approach the subject?


texts: How to pick a scope and probe to measure a 12.5Gbps signaling frequency?

texts:
I fully realize that this signal frequency range is high enough that we do not have scopes and probes today to actually measure the rising edge and see it. This question is a hypothetical question to understand how to pick a scope and probe.

This is my understanding / answer / math for the problem, is it correct?

Signal Frequency, Fsig = 12.5 Gbps
Time Period,      Tsig = 1/12.5 Gbps = 80e-15 (80 femto second)
Rise time,        Trise = Tsig/2 (?) = 40e-15 (40 femto second)
Knee Frequency,   Fknee= 0.5/Trise = 0.5/40e-15 = 3.125e+13 Hz

And we do not have probes or scopes with that high of a bandwidth (3.125e+13 Hz), right?

I want to know if my calculation is correct?


texts:
I am a novice in electronics and wanted to design PCB , as a final year project i am planning to do something related to room heaters so i have decided to use Kapto/polymide material for that.

I am planning to build a PCB like mentioned in this link
Kapton 12v (4" x 2")
Can anyone guide me how to achieve this using a Kapton film like this

Any suggestions regarding process or steps for this particular use case would be helpful


texts: Which resistors are taken into account when evaluating the discharge of a capacitor

texts:
I'm trying to evaluate the time it takes the following mono-stable circuit to change the voltage of the capacitor from 1.25V to 2.5V after the Vin single pulse enters, and evaluate the recovery time of the circuit (given the voltage on the capacitor should be 5mV from zero for full recovery).

In the official solution, the tau is calculated as \$\tau = (R1+R2)C1\$ while i thought it should be only \$R1\$.
Why are both resistors taken into account? Isn't the charging voltage Vout charging only the upper side through R1?
What happens in the discharging process? Again is it discharged through both of them?
For the recovery time, the official solution states that after Q changes back from 1 to 0, the voltage in Vc drops from 2.5V to 1.25V (VDD=5V). I understand the the voltage on a capacitor should be continuous, but how did they calculate it?
Is it because the change in the voltage for R2 is 1.25V, so that was the 'drop' in voltage there?
Somehow I'm missing the point of calculating the voltage drop on the capacitors.

Many thanks!


texts:
I read in this book:

Why can’t passive filters provide a gain higher than 1. Isn’t that exactly what happens at the resonant peak of RLC filters ?


texts: BMP085 and Humidity and Temperature Sensor with arduino

texts:
I am doing a project that requires me to use a BMP085 (with breakout) and a humidity/temperature sensor (with Breakout).

I am trying to attach both of these to the arduino uno through two analog inputs (they both use an I2C bus). I need to know how they will be hooked-up and how they can be programed. Both sensors have a sample code for finding the values individually (the humidity/temperature sensor also has a library).

I am currently trying to simly attach the two SDA and SCL inputs and placing them in the correct place for the arduino Wire library but I cannot figure out how to make sure the code works. I would like to avoid using 2 arduinos and I only have 1 extra analog input after the 2 I2C pins are placed in A4 and A5. The only digital inputs are the ones needed for ardumoto.

In the final code, I need to find humidity, temperature, and pressure (it would be best if I could get three methods to do this).


texts:
I realise Eagle is primarily a PCB layout tool, but I would like to use the software to draw schematics I will use in reports. I won't be using these schematics for any PCB layout.

What I need, which is not included in the standard library is a proper DC and AC voltage source like these I found on a SparkFun tutorial:

If there's no such library, is there an easy way to draw these symbols for my own library?


texts: Left Hand Rule vs Right Hand Rule and the Resistance Generated

texts:
Some say that Hall effect takes place prominently only in semiconductors because their impurities create resistance in the presence of magnetic influence, but in case of conductors like copper such Hall effect would be negligible.
My question: Assuming copper wire is used... As per the pic shown, am I right to say that if both rules are activated at the same time, i.e. current is switched on to flow through the wire (left hand rule, as per motor) while at the same time the magnet is independently moved from left to right (right hand rule, as per generator), there is no resistance against the initial direction of the current flow, provided the speed of independently moving the magnet does not exceed the speed that which would generate larger current flow in the opposing direction?
In other words,

If an X amount of current is flowing through the wire that would generate Y amount of force (observing left hand rule)...
While the magnet is independently moved in the same direction at the same Y amount of force (observing right hand rule)...
Then there is no resistance to the initial current flow (or at least negligible resistance as per Hall effect).

Am I right in this?
Note: 1 ohm resistor is used in the pic just as an example for the purpose of preventing short circuit and has nothing to do with the main question.


texts: Help Identifying a Differential Pair-Like Symbol in a Schematic

texts: I am working on an adapter to connect a Xerox Docutech keyboard to a modern computer. This keyboard used a specialized, keyboard/mouse interface that does not have a modern counterpart. I have a schematic for the interface but I am uncertain about a symbol it depicts. As you can see below, the KbrdData + and - lines connect to what looks like a differential pair that generates a single, "DataFromKbrd" signal. They look a bit like op-amps... but I have no idea how those would help in this situation. What exactly are these components? How would I go about making one out of modern parts?


texts: How to simulate and or calculate complex impedance of LC circuit

texts:
Let's say I have a matching network made up of inductors and capacitors like this.  How would I go about simulating to get the complex impedance of this circuit at my frequency of interest.  Something in the form 20+15j for example, or I guess even a Smith chart (I'm trying to relearn those).  Can I do it in spice?  Should I do it by hand or maybe I need something fancier like an RF simulator?

simulate this circuit – Schematic created using CircuitLab


texts: What's the spacings specification between traces on a printed-wiring board

texts:
According to a UL/ULC standard, the spacings between traces of the PCB is specified as below table

I am quite curious about the spacings. Because there are many IC circuit components with very short clearance due to the trend of smaller IC. Such as the MCU chip the clearance between pads is as small as 0.3mm.

quote from the ULCS531 standard

My device is a 24VDC powered smoke detector that has a PCB inside.


texts:
I found an article about electronic loads and tried to simulate the circuit in LTSpice. However it didn't work.

Here is the link to the full article, where I tried to recreate the following figure:

Do you agree that this circuit is wrong and not working!? I'd argue that we have to use an integrator (PI controller) instead of the lone operation amplifier.


texts: How to find Thevenin resistance of circuit with voltage source and three resistors?

texts:
The question is:

Replace the circuit with a Thevenin Equivalent Circuit and find the Thevenin Resistance (Rt) in ohms.

I've used Thevenin before and solved quite a few equivalent circuits as well.

Unfortunately, with this circuit, I'm getting very confused on how you would exactly go about combining these resistors. Are they in series or parallel?  Or are two of them in series with the other one? That's where I get confused.

simulate this circuit – Schematic created using CircuitLab


texts: CAN: Difference between an MCU with CAN embedded peripherals and one that does not?

texts:
For example, an MCU (stm32, esp32, Pic18f .. etc) with CAN embedded, sends logic level signals through pins Tx and Rx.

They only need a signal converter. (example: MCP2551).

My question: Why can't any MCU with tx and rx pins use just one signal converter? Why does this also need an adapter? (Example MCP2515).


texts:
I want to start by saying im really not educated with ohms law and how to figure out this equation that im dealing with. Okay, so currently I have an older 1997 F-150 that i converted the headlight bulbs into Leds with (6 ohm, 50 watt, 2.25 amp draw) load resistor kits. Now i’m trying to put custom tow mirrors on with leds but i’m needing to run 2 wires from the led headlight bulbs (after resistors) back to the mirrors through the doors. The headlights have 2 power wires (turn signal and running light). So i spliced into those two wires with 2 diodes (3 amp - 12v) to run to the (1 wire) led tow mirror light. I’m looking to install another resistor for the running light to the tow mirror led I am just not sure what size resistor because i don’t want the tow mirror led too dim where it is not noticeable. The idea im trying to do is here at this link.
https://youtu.be/EyOcy_WdeNs


texts:
I'm putting together a buck regulator (first time around) based on the lm2374 chip. TI provides gerbers of a recommended layout for this chip family, but my configuration differs a bit. I've read up on ground bounce, and nominally understand that I need to minimze changing loop areas, but am having a hard time understanding what the loop here would be.
I'd like to get feedback on the PCB layout with regards to possible noise/EMI:

I've overlaid additional part names in yellow to make it easier to match up with TI's recommendations / general components. You can ignore the air wires, one is an enable line that hasn't been hooked up to the MCU yet, the other is the battery line being needed elsewhere and eagle drawing the airwire from that particular spot.

Please let me know if/what can be improved here. Thanks.

EDIT Looking at this for the umpteenth time, I do see that I tied the EN pull-up to VIN, not VOUT. I'll make that change.


texts: Bi-directional High Side Load Switch Design

texts:
I want to design a high side load switch which can allow or block DC current in either direction based on a 3.3V input.
Some considerations:

The 3.3V rail is potentially created as a result of power being applied on either side of this switch, so with the thought that the 3.3V rail may still be coming up, the switch should be open (blocking) with it not present.

I would like to switch voltages up to 20VDC.

The circuit that I have currently looks like this:

This works with some caveats:

Some current passes through for about 10ms when power is applied. I'm not sure I completely understand why but I'd like to mitigate/remove that. For it to be that long, it would seem to not be related to the switching time of the MOSFETs, and swapping the 100k resistors for 1k didn't change it.

For switching 20V, I need to select P-FETs where Vgs can be 25V or greater, which limits my parts selection. This is not the end of the world but maybe there's a better way to do it.

How can I improve this circuit, use smaller/cheaper/fewer parts, and mitigate the caveats above?
This is ultimately part of a USB C power mux circuit as I mentioned in my previous question, so ideally I want to be able to have two of these and open one, or the other, or neither, but never both at the same time (because then 20V may end up on my VBUS rail and that's no good for anyone). This may be out of scope for this question but I provide this info to avoid the XY problem.


texts: Very low current (<10 microamps) darkness detector circuit that turns off in light

texts:
I've made a device that lights an LED at a very low current (<10 microamps) as a very dim indicator for use in the dark.

At its simplest, the circuit is a 3V coin battery + resistor (300K-1M ohms) + LED.

I'd like it to turn off when there's ambient light in the room and, ideally, draw no power whatsoever to save the small battery it runs on.

The darkness detectors I'm aware of, however, use a transistor and photo detector to accomplish this (see https://www.buildcircuit.com/darklight-sensor-using-transistor/), and typically draw power in ambient light when the LED is turned off.  These work at when running the LED at ~10-20mA, but just tinkering, I haven't been able to make these function at the low <10uA currents I'm trying to work with.

Any ideas on a better way to switch off a low current LED circuit entirely when light is detected?

Thanks --


texts: Shannon versus Nyquist bit rate calculations

texts:
I am confused with the shannon channel capacity formula
Versus nyquist bit rate.

nyquist formula contains signal levels while
Shannon formula doen't, how to refer to signal
Levels in shannon's formula ?

I would appreciate an example for channel capacity
Using both formulas


texts: Positive and negative terminals on a battery

texts: Sorry, this may be a newbie question, but is the positive and negative terminals on a battery refer to which side has a higher potential? Or one side has positive charge and one side has a negative charge?


texts: How to transmit CAN signals wirelessly without line of sight (LOS)

texts:
I have a scenario where I have an OBD-II interface transmitting data via CAN across six wires to a display. I will have power on either side of the wires, but I cannot assume that the wires will have LOS (cable will be tucked away, so IR isn't an option). I would essentially like to cut the wires, and transmit the data wirelessly between the two ends.

I have done a little reasearch and found these encoders/decoders.

These encoders/decoders will not transmit data. Apparently they just litterally encode/decode wired signals. But as little knowledge as I have on this topic, I'm not sure if they will accomplish what I'm after.


texts: TDA2030A gain reduction for Headphone Amp

texts:
I have a TDA2030A based amplifier that should make a decent headphone amp except that its gain, at about 32 dB, is way too high.

It would be easy to change the gain setting resistor or even put in a switch to change the gain from say 10 to 15 to 20 dB for proper Headphone use. But there is a problem.

The TDA2030A data sheet says the chip needs to run at a gain in excess of 24 dB to maintain stability.

A resistor could be placed in series with the output. But that destroys damping factor and sound quality. That is not an acceptable solution.

Meier Audio uses the TDA2030A in their Corda Brick. It has switchable gain of -1 to +14 dB. So how do they do that with the TDA2030A?

Anybody got a working circuit they will share that gets the TDA2030A down to a stable switchable gain of 10-15-20 dB?

Suggestions?


texts: Questions on load modulation, Doherty PA

texts:
I was unable to understand a bunch of stuff related to amplifiers. Specifically my questions are as follows:

What is load modulation? If i have a load of impedance of 10 ohms physically, then does load modulation change the impedance of this load? Does anyone have the theory behind load modulation to share?
What is the difference between "active load modulation" and "active load pull"?. Furthermore what is the difference between active and passive load modulation?
Doherty power amplifier: DPA uses a quarter wave transimission line. Does that mean DPAs are not suitable for low freqencies (less than 100kHz) since the transmission line length will be too long to integrate in chips? Also is it possible to avoid the transmission line?

I have not found any literature which has answered these questions, maybe i missed some. I would really appreciate some help from the experts.


texts: Replace tiny resistor with a physically larger one?

texts:
I'm looking to replace a resistor on a key sender unit from my Mum's car. The part is about 2 mm and too small for me to solder. Can I replace it with one that I can work with easier as it is bigger? I'd like to replace it with one with terminals so I can solder to the board.

Similar component shown here:


texts: Proper usage of a center-tap transformer

texts:
I'm attempting to design a high-precision voltage source for use in an optics lab. My starting point has been the application notes provided by Analog Devices; specifically, Fig 16:

The transformer recommended by the author is over $80 and has a very sparse datasheet. Moreover, for my application, I do not need 300V output. I have been looking around for suitable replacement parts and came across the Power Integrations SIT1253I converter, which seems to have a 1:10.66 turns ratio from the primary to secondary side. I am planning on providing 12V input to the start of the primary-side winding, so that the nominal maximum output of the secondary-side winding is ~128V. Moreover, I am planning on tying pins 3 and 2 together and wiring them to the control circuit depicted in the above schematic so that the voltage can be tuned from 0-128V.
Am I correctly understanding how to use this device? Is this a suitable replacement for the Pico 32195 transformer recommended in the Analog Devices application notes? Any insight would be much appreciated.


texts: Home door "open/close sensor" without installation

texts:
I want to make an application/PCB with a microcontroller circuit. The board containing the MCU will be placed inside the door lock, in one like that:

A side:

At the door frame on the wall, we have this:

B side:

I want my circuit to know if A is very near from B or not, that is, if the door is closed or open.

The picture below is a common way to make such sensor, but this idea will not be accepted for my project, I need something that will required none of sensor installation. I need a sensor that could be placed only on "A side", nothing on B side or other places. In "A side" I will be able to make openings on the metal of the lock. As can seen, B side has a free space at the middle.
Is that possible in a simple way?

The picture below shows something that I want to avoid, avoid any kind of external installation.

Would something like this work?
It is TCRT5000 of Vishay: http://www.vishay.com/docs/83760/tcrt5000.pdf


texts: Why does this H-bridge have PWM and Enable pins?

texts:
The BTS7960 H-brige has 6 pins (excluding current warning pins).

Right Turn PWM
Left Turn PWM
Right Turn Enable
Left Turn Enable
VCC
GND

I usually connect all the "Enable" pins to HIGH and only use the PWM pins to control the motor speed and direction.  That works perfectly, but is that a good practice?

Are the "Enable" pins really unnecessary or am I missing something?


texts: iPhone Headphone Jack - Accessory & Headphone Use

texts:
I'm working on an iPhone accessory that consists of a temperature sensor and LED. I want to power the accessory through the iPhone headphone jack, but I'm concerned that the user can't use headphones while the headphone jack is occupied by the accessory. I am considering Project HiJack to create build this. (http://www.seeedstudio.com/depot/hijack-development-pack-p-865.html)

Does anyone know if it is possible to have headphone jack power an accessory, provide some application data, and be used to reroute the audio data into a second jack built into the accessory as well?

Maybe a RCA splitter adapter is a solution? Would a splitter adapter interfere with HiJack and function properly with such a set up?

Thanks


texts:
I'm working on a project where I will be using a bunch of RGB LED's. I bought a quantity of this style of LED holders:

https://www.sparkfun.com/products/11147

The way they work is you slide the LED in the threaded end of the holder and then insert the plastic plug behind the LED and that holds the LED in place. The problem I'm having is that the plug only has enough space for the two prongs of a standard LED. With my 4 prong RGB LED it is not compatible.

If I wasn't concerned with being able to remove the LED from the holder or drying time is there some material that I could pour in behind the LED to take the place of the plug? I'm sure it would need to be non-conductive. Basically I'm thinking I can put the metal holder face down, drop the LED in, and then pour some glue, epoxy, etc in behind it to fill the rest of the cavity. This would prevent the prongs from touching each-other as well as keep the LED in place. I just don't know what type of material would work for this application.

Alternatively does anybody know where I could find an LED holder for a RGB LED?


texts:
I'm trying to design a circuit that will drive a relay (and thus turn on a bigger circuit) when the correct "key" circuit is connected.

The "key" is contained within the hashed box and functions as I would like
(returns AC voltage, which is then "smoothed" back to DC by the main circuit.

Running a simulator, the return line from the key "smooths" out to 2v with 140mA.

So.. what I'm looking to achieve: When the key is connected, the relay needs to close, switching on the bigger circuit.

What have I done wrong / what do I need to alter?

(I'm extremely new to electronics!)


texts: Why is i2cset giving "resource busy" on my BeagleBone Black?

texts:
After trying to get Adafruit's 8x8 LED Matrix python example code to work on both my Raspberry Pi and my BeagleBone Black, I realized there is probably something wrong with Adafruit's code and not me.  The matrix is working just fine with a Teensy3.1.

I decided that this is a good time to cut my losses and learn how to program i2c.

In my first steps I came across this useful blog where someone did this using the i2cset command.  Unfortunately the device seems busy.

Any ideas?

According to one person,  "UU" on the i2cdetect, could mean "Probing was skipped, because this address is currently in use by a driver".

Others had also mentioned "modules" that may already be using the i2c bus, and that one could remove these "modules" and try again.


texts:
I'm trying to use an Arduino to enable/disable a 12V solenoid. I used an H-bridge and got that working fine. Then, I decided to simplify things and get a single mosfet instead of a multi-channel H-bridge and have gotten myself very confused. I'm trying to understand the proper way to use a P-channel (or N-channel) mosfet in this setting, and came across this sample circuit on google:

Why is there another transistor involved (the 2N3904), and why is there a diode across the load?

I understand that a P-channel is activated when \$V_{gate}\$ is brought high (above \$V_{source}\$ + \$V_{drain}\$), hence the pull-up, but why the extra transistor? Shouldn't the MCU (in this case the PIC) be doing the same thing?

Also - in the scenario when all I'm doing is turning a load on or off (like my solenoid), is there a reason to use an N-channel vs a P-channel?


texts: Why is called n-type and p-type semiconductor? What is behind the choice of n and p as letters to represent the 2 different types of semiconductors?

texts:
This is a naming question, not so much about electrical engineering.

I keep forgetting/mixing up which is the n-type and which is the p-type semiconductor.

Usually the names act like mnemonic devices for us to more easily recall which object is associated with which label/word.

What does the n stand for?

What does the p stand for?

For example, I would name it h-type form hole-type instead of p-type to remove the confusion. But I'm assuming there is already a connection like this behind the use of p and n letters - i just don't know it.

Are this just arbitrary names/letters? (doesn't make much sense to be arbitrary)

What keeps you personally from mixing the 2.


texts: A processor is working at 100 MHz. The program memory interfaced to it can work only at 25 MHz maximum. Is there anyway we can fetch an instruction from it in one clock cycle of the processor ? I read that instruction cache can be used for this purpose. How instruction cache actually makes instruction fetch faster, while we cannot increase the speed of the slow memory ?


texts:
I'm doing a course in which I need to connect a wheatstone bridge (which contains a light sensor) to an op amp.

I'm using the same devices and voltage supply (9V) as the course, still, when I measure the voltage in the nodes I'm supposed to connect to the op amp I obtain a voltage that (as far as I understand) is too high for the op amp, let me explain:

This is the circuit schema:

The op. amp. datasheet (OPA344PA) is here op. amp. datasheet

From the datasheet,I can see that the input voltage range (VCM) must be between -0.3 and -1.8 V, right?

Now, according to this document Input and output limitations of an op. amp., VCM is (VIN+ + VIN-) / 2.

VIN+ and VIN- are the two nodes of Vout in the whatstone bridge. One of them is fixed, the other comes from a sensor, so it varies.

I have measured both of them with respect to ground (in the case of the sensor, I have taking the maximum voltage that I can get with the current illumination). These lectures are: 1.651V and 2V.

Applying the formula above, I obtain 1.8075. First of all, that value is positive, when the datasheet states that the input voltage should be negative. Even ignoring that, that value is a bit higher than 1.8V, so I guess it's not safe to connect the current circuit to the op amp (if some light is turned on and the sensor voltage becomes higher, it will get much worse)

My question is: Is the above reasoning right? If so, I guess I should use smaller resistors for R2 and R4, so the voltage drop is greater through R1 and R3. Is this correct?


texts:
I need to measure torque output of a PM DC electric motor.  My plan was to use a current clamp to log the current vs time, a voltmeter to measure volts vs time, and an encoder to log rpm vs time.  Then I would use the equation
T = (7.0429*I*V)/n to get torque vs time.  Where T is torque in ft-lb, I is current in A, V is voltage in V, and n is angular velocity in RPM.  This comes from the link between power, torque, and rpm, and the 7.0429 is just to get units of ft-lb.  I don't have the efficiency and I can't get the stall or free load values because its installed in a machine.  I do have a plot of RPM vs torque and Amps vs torque on the same plot.  Can I use this to back out torque values as I log current and rpm?


texts: Can a small voltage represent a closed circuit?

texts:
I know this is somewhat of an odd question, but I'm curious about whether or not a small (or maybe matching*) voltage on a wire can represent a closed switch.

** more about this in a moment*.

First of all, take a look at this terribly simple (and poorly drawn illustration) of my garage door opener set up.

Okay, so when I press the wall switch button the circuit is closed and the garage door opener is activated.

Here's what I'm curious about:

If I took the ground (neutral) wire and plugged it into a bread board and applied 5v directly to that wire, would the garaage door activate?  Would that represent a closed circuit to the system?  Is that dangerous to do?  I would think not, since it is only 5v.

Not Mains Power

Also note, those wires represent just the activating switch, not the mains power.  That's why even though this is connected into a US home (wired as 110v) the line shown is only about 5v.

Relay

I know I could attach a relay to a bread board, then connect both the hot and ground to the bread board through the relay (via NO) and then apply voltage to the relay thus closing the relaying switch and completing the circuit.

However, I'm wondering if in this case (low voltage) if you could just apply 5v to the ground to simulate the circuit closing.

I'm not sure if what I am saying is dangerous or there is another way to do this or if the answer is simply use a relay and forget about other methods.

EDIT - Added another diagram and more notes

So imagine that the bread board in the diagram is used and the ground is now connected to another power source of 5v.  Now I can apply the 5v from the other location or I can close the original switch.  Can you explain why this is a problem?  A short when both are on maybe?  But if they were guaranteed to only be one on at a time would it work?

Edit 2 - added schematic

Okay, take a look at the schematic.  We're talking about the momentary switch section.  It's 12v.  That's fine, change my diagrams above (in your head) to 12v.  :)
There are comments that say "don't do it!!!"  That's fine, I believe you, but can you explain why or why not?  And don't just say, "you'll die!"  :)

Edit 3

So I guess it was this that I was thinking of -- either switch being able to turn it on -- but I guess that does use the same source voltage so maybe that's the thing:


texts: Flammability of Silicone Sealants with Electronics

texts:
I'm aware that electronics grade silicone rubbers exist but I've also read in a particular post on here that common silicone rubber sealants can also be used for electronics, providing that they're neutral cured and not acid cured.

I'm working on a project where I'd love to use a common silicone rubber sealant as a) I have an abundance of it and b) if what I have is not appropriate there's many hardware stores close to me, but all the SR products that I have and whats available at the hardware stores list that they are flammable and to keep away from sources of ignition.

Is there a reason flammability wasn't mentioned in the above post? Am I overestimating the ignition potential of an electronic circuit?


texts: Why can't high current substitute low voltage

texts:
I know this look stupid, but why high current can't substitute low voltage.

I read many articles about the difference between the two, and asked my professors, but still have some doubts and blind spots to differentiate between them.

let's say a diode, I need 0.7V to make it operate, why if I decrease the voltage below that and significantly increase the current it still doesn't operate?

I tried to visualize the current as an army (quantity) and the voltage as the power of the that army. And thought even if the power is low if I increase the number of my army I would substitute the low power.

I know this is not true, but why?


texts: I was wondering if it would be possible to increase the frequency of a signal by a fixed amount. Basically, I have a negative wire soldered to a speaker and a positive wire that very quickly breaks/unbreaks the circuit. As expected, this causes the speaker to pulse each time the positive wire breaks and unbreaks. However, the frequency is very low and I was wondering if it would be possible to have a circuit that "adds some frequency" to the current frequency so that I would get a continuous beeping instead of some pulsing with noticeable space in between. The circuit would have to be pretty simple since I'm making it myself. Is this feasible or should I just be happy with what I have?


texts: Wifi router setup Question regarding amperage/voltage drop

texts:
Ok, so I will keep it as short as I can.
5v dc power supply
3A load
Traveling over CAT5e, distance = 275'
2pr pos, 2pr neg.

At device point, reads 5.25-5.28v on meter (device not connected) Is the "Voltage Drop" I read about, only when "Load" (Device) plugged in? since I don't see a drop on the meter?


texts: Rectangular Waveguide H-Plane Step Discontinuity - Equivalent Reactance for Change in Height

texts:
I have been reading Pozar's Microwave Engineering, and in Section 4.6, he goes through the analysis to determine the reactance of a discontinuity between two coupled waveguides. In that chapter, he describes how using two waveguides with a difference in width, it is possible to determine the equivalent parallel inductance. In the same section, he claims that a change in height would result in a equivalent parallel capacitance.

However, I am unable to follow the analysis that he does for change in width and apply it to change in height. The main issue seems to be that the TE10 mode is only dependent on X and not on Y. Therefore, it almost appears that the change in height has no effect on the reflection, which obviously makes no sense.

As a reminder, the TE10 mode has transverse components of the form

$$E_y^i = \sin(\frac{\pi x}{a}) e^{-j \beta_1^a z}$$

$$H_x^i = \frac{-1}{Z_1^a} \sin( \frac{\pi x}{a}) e^{-j \beta_1^a z}$$

and at the boundary plane, continuity equations ought to be applied.

I think the main issue I have is with this following sentence regarding reflected modes in the second guide:

  Because there is no y variation introduced by this discontinuity, TE_mn modes for m \neq 0 are not excited, nor are any TM modes. A more general discontinuity, however, may excite such nodes.

In the change in height case, there is only y-variation. I do not know how to apply that y-variation to this condition to determine what transmitted modes into guide 2 ought there to be!


texts: In DDR3, DDR4 DRAM ,I don't get the point that each column gives more than one bits?? Column decoder is also a mux which selects one of the bits in row buffer, and DRAM array is a crossed structure with each column is essentially a bit line. How could there be 4 or 8 bits per column??


texts: Logic Levels between 5(V) and 3.3(V) devices

texts:
I am using a 5V microcontroller to communicate with a Bluetooth module operating at 3.3V.

I have regulated the output from the 5V microcontroller rail to 3.3V rail for the Bluetooth module.

Since I am using a UART, I need to use a TX pin to go to the RX. The issue here I found is that the pins to the Bluetooth module aren't tolerable to 5V. So I decided to use a voltage divider to get 3.3V on the output.

Now, I got the UART TX working on the microcontroller side. Connecting to the RX of the Bluetooth, I see a logic 1 at the output.

After some debugging I found that infact the logic level is shifting between 2.3V for logic 1 and 1.79V for logic 0 (but this doesn't register as a 0). I presume 1.79V. Looking at the schematics of the Bluetooth Module, I found that the RX pin seems to be in tri-state between 2 resistors to VCC and GND. I need a 0V or lower than a certain tolerance for logic 0.

What can I use to get the proper logic level on the output for proper serial communication?


texts: amps were lower on ohms law math than what I read with live at the equipment?

texts: When using ohms law on a residential A/C unit I got 7.3, But when using the multimeter it dropped to 5.5. What can cause this?


texts: Difference between negative terminal and copper ground?

texts: What's the difference between Negative and Ground? Like a negative terminal and a copper ground? I was reading that they are both the same; one person stated that negative is just more negative than ground. What's the difference? Do I even need ground if I have a negative terminal?


texts:
What do the 2/1 4/1 16/1 labelings mean?
What would you search on google to find the answer? I've tried searching
mosfet diagramming labeling 4/1 16/1
MOSFET diagramming

Origin of pic: https://www.youtube.com/watch?time_continue=317&v=9AyLv4_e_24


texts: Bipolar junction transistor drawing more than 1 amp

texts:
I am trying to use a bipolar junction transistor to sink the current on an output pin:

simulate this circuit – Schematic created using CircuitLab

But when the base of Q1 is connected to 0V, and the base of Q2 is connected to 5V, there seems to be a large amount of current going through Q2 (1.28 amps). The only possible path that the current could take is from the base of Q2 to the emitter of Q2.

UPDATE: I meant to say "The only possible path that the current could take is from the base of Q2 to the collector of Q2."


texts:
Hi when I use the systemverilog, there are some confused point.

first one is distinguish about DPI and DPI-C.

as following example used DPI not DPI-C . but As I know DPI-C is used to in C.

CODE:SV_file.sv
program main;
logic a;
import "DPI" function void show(logic a);
initial begin
a = 1'b0;
show(a);
a = 1'b1;
show(a);
a = 1'bX;
show(a);
a = 1'bZ;
show(a);
end
endprogram

CODE: C_file.v
#include <stdio.h>
#include <svdpi.h>

void show(svLogic a){
if(a == 0)
printf(" a is 0 \n");
else if(a == 1)
printf(" a is 1 \n");
else if(a == 2)
printf(" a is x \n");
else if(a == 3)
printf(" a is z \n");

}
RESULTS

a is 0
a is 1
a is z
a is x

Would you let me know how to use the DPI and DPI-C?


texts: Using ultrasonic sensors to measure distances to multiple objects

texts:
I'm doing a project which using ultrasonic sensors to measure the distances to objects.

As far as I know the sensor can only measure the distance of the closest object to it. Is it right?

And in case there are multiple objects, can the ultrasonic sensor be able to detect distances to those?


texts: Unable to diagnose StX fault in Modelsim

texts:
I'm unable to figure out why Modelsim is giving me a StX fault for this testbench.
I'm just creating a counter and simulating a device that returns the MSB of the counter. Any help in figuring out what mistake I'm making will be much appreciated!

module test (i_clk, ctr, o_wf);
parameter size = 4;
input wire [(size-1):0]ctr;
input wire i_clk;
output wire o_wf;

reg msb;

initial msb <= 1'b0;
always@(posedge i_clk)
    begin
        msb <= ctr[(size-1)];
    end
assign o_wf = msb;
endmodule

`timescale 1ns/1ps
module test_tesbench;
    parameter size = 4;
    reg i_clk;
    reg [(size-1):0]ctr;
    wire o_wf;

initial
    begin
        i_clk <= 1'b0;
    end

test DUT(.i_clk(i_clk), .ctr(ctr), .o_wf(o_wf));

always
    begin
        #(0.1) i_clk <= ~i_clk;
    end

always@(posedge i_clk)
    begin
        ctr <= ctr + 1'b1;
    end
endmodule


texts: Is there any way to calculate the voltage & current rating on an unmarked component?

texts:
I just acquired an assortment of electronic components, many of which either have no way of identifying ratings at all (ie resistors) and some ie (transistors) where there has either been no printed identifier or it has worn away.

I know they are cheap to replace, it's the question that interests me, not the products.


texts: RF shield needed for BLE SoC in PCB design

texts:
I´m checking the implications of using BLE in a new design.
This design will include in the same PCB a BLE SoC, the specific matching network and an anetnna (still checking if I´m going to use a ceramic antenna or just route an antenna in the PCB as a track).
The device must be CE compliant, with the main EMC tests etc.

The question comes when I have to decide if an RF shield is needed or not.

I´m absolutely new to RF design and the implications not using an RF shield in this type of circuits are not clear to me.

Could you please help here?


texts: Understanding SPICE code in Chan Transformer in LTSpice

texts:
Taken from here:
http://ltwiki.org/?title=Transformers

I am having trouble understanding how the Chan core is actually linking in with the coils.

Does anyone understand what the SPICE code is doing here? Especially in the second half? It may just be lack of familiarity with the syntax or keywords being used.

Xp and Xs are supposed to be coils so I only expect two terminals, but there are three terminals and the Chan core mysteriously links to this third terminal.

But if that is the case then what are the actual Xs and Xp components in the simulation and how is it being interpreted by LTSpice? It seems like it has something to do with the "Winding" keyword but I haven't been able to find out what that is or how it works.

Is the third terminal special terminal activated by the "Winding" keyword that is meant specifically to determine the core? But if it is, then why does the core have two terminals (the other of which is permanently connected to GND via the paramterization in the first half of the code) since there's no current flowing through the core?


texts: I want to connect mic to audio output in arduino?

texts:
My knowledge in electronics is poor.

I want to output audio stream from mic to audio
And I use following code in Arduino

 val = analogRead(analogPin);
Serial.println((int)val);
tone(SND_PIN, val);

It outputs some value, for example 1023, what is this?
Is this code right, and can we connect to mic directly from arduino?


texts:
I'm constructing / moving a low power fm radio station to a new location. The antenna is a new folded dipole mounted on a 2-3/8" steel pole and attached to a new magnetic base. This location is the top of a 35" high water tank. It is near the edge of the tank and about 4' above the tank surface.  The tx is a Bext XT100 exciter loaded into a interference filter and wired to the dipole with 65' of new LMR 400 line with type -n connectors. I have removed the filter for a test and still have the same condition. My next step will be using a 100 w 50 ohm load to test all points to the antenna.

This station was on a am tower with a monopole in the past and had no issues. I have never worked on a steel structure that is grounded. Is height above the tank an issue? or am I missing something basic.


texts: How do inductive chargers detect a load?

texts: For a wireless inductive charger, I understand the basic operating principle. I have a question regarding the operation of such chargers when no "load" is "connected". How do they detect the presence of a "load" so that the transmitter doesn't constantly have to transmit?


texts:
I have a Arduino sketch that can rotate 2 stepper motor using a stepper driver that has 256 micro stepping.

I used Arduino MEGA timer 1 and timer 3 with fCLK/8 prescaller for generating step pulse for each stepper driver.

In my code I used ISR for toggle the pin state as below:

ISR(TIMER1_COMPA_vect) { //top motor
  PORTL ^= 1;

}

ISR(TIMER3_COMPA_vect) { //bot motor
  PORTL ^= (1 << 4);
}

This ISR use program time while toggling the pin state (it takes few uS and if timer interrupts become higher frequency, it take more time from main program). It is a problem for Serial communication of the Arduino.

I want to generate pulse with different frequencies between about 100Hz to 67kHz.

Is there any other way to generate a pulse using Arduino?
Is there any dedicated programmable pulse generator IC for my application? It should has a communication interface to mealtime frequency change.


texts: Can anyone identify the components circled in black? Weber 6049A Schematic

texts:
I have a 1936 era Weber amplifier (6049A.)

Can anyone help me identify the 2 components I have circled in black?

Red/Purple and Orange/Black (one of the other components also has a green circle on it.)

Also, a lot of wires are cut, does anyone happen to know where I can get a schematic for this amp (2 56, 2 2A3, and 1 5Z3 tube)

I have measured some of the caps, I got:

Major Clr ! Minor ! Dot   ! Measured
----------+-------+-------+-------------
Red   |Violet | n/a   | 3.19k, 3.01K
Orange    |Black  | n/a   | 35,2K, 42K
Brown     |Black  | green | 1.02M

Is it right to assume that if there is not a dot on the long (most) color of the
resistor that the multiplier is the same color as that long (most) color?

I have started to construct a schematic:


texts:
I am new to the field of embedded systems. Recently I was learning about the differences between different bit size (8, 16, 32) microcontrollers. What I found was that the size of bit indicates the memory addressing capacity, data bus and address bus size etc. Every other website has almost the same explanation. But still I could not find answer to some of the questions. To list them:

Is it really necessary for the address and data bus to be the same size as the bit size of the micro.
What is it that will become fixed for sure for a given bit sized microcontroller?
Do a microcontroller have have same address bus for all the memories (RAM, flash, EEPROM) and if so, is it the choice of manufacturer to allot any size to any type of memory out of the available addresses?
Say there's an 8 bit microcontroller. So it can adress 2^8 memory locations (that's what I figured out, I am not sure). If each register is 8 bit it means a total of (2^8)*8 =2048 bits of memory. That's not even close to the 32kb of flash inside most of them. What blunder am I making?


texts: Is curve fitting to a sinusoidal function with Microcontroller possible?

texts:
I have 2 sinusoidal waves with a frequency of  2 kHz rectified and being sampled at 50 kHz by two ADC channels (10bit) of a PIC18F26K22.

I want to find the measure the amplitude of each sine and the phase difference between each other. I could use ZCD do detect the phase difference and use the adc just to sample the amplitude, but i was looking for a more smarter and all-in-one wide approach.

My question is if the uController has the computational power and if it possible to do a curve fitting with a uController in other to extract those 2 parameters.
Getting an ADC with higher sampling rate and resolution is a open possibility, of course.

Edit: To make give my question a context/frame, what i'm looking for is to measure an impedance, i have the signal corresponding to the voltage drop in the impedance and i have another signal corresponding to the current sensing circuit. So I need to sample both to measure each one amplitude and phase difference.


texts:
I recently bought a car with an iPod dock. When I plug in the iPod disables and I am forced to control it with the car's audio controls. I want to get around this.

Can I simply yank pin 21 from an Dock Connector cable to disable the car's control of the iPod?

Reference: http://pinouts.ru/PortableDevices/ipod_pinout.shtml


texts: How to measure high-voltage and high-frequency ripple?

texts:
I have a ferrite transformer outputting 1.2kV RMS on it's secondary. I have added a diode to do half-wave rectification, and have added a sufficient capacitor (10nF) in parallel to deal with ripple. It's more than enough, according to the formula \$dV = \frac{i}{fC}\$

I'm using 32kHz on the transformer, and I plan to draw at most 500 µA. This should give me a very small ripple.

However, to measure ripple, I tried using a 1000:1 high-voltage probe. It has 1GΩ  impedance, and it's rated for 60Hz only. Measuring my rectified / filtered voltage shows a lot of gargabe and a huge ripple, around 800V, but I suspect this is false, given the probe's inability to deal with higher frequencies, probably.

I also tried a voltage divider using 10MΩ  and 100kΩ  regular 1/8W resistors and a regular scope probe on the 100kΩ  resistor, but results are quite similar.

Changing the capacitor or removing it completely changes the ripple just a little, about 10% better or worse.

So, my question: is it normal to get false results with those probes (or voltage dividers) on high-frequency voltages?

Is there a safe and reliable way to measure ripple on this particular scenario?

UPDATE:

Here is the distortion I got on the secondary, after rectification and filtering, to illustrate the question a little better:

After reading the suggestions of everyone, I decided to do a test I didn't do before: I made another transformer, with a secondary of about 170V. That way I could use a regular 10x probe (without any voltage divider), and compare it's performance with the 1/1000 voltage divider, but keeping the 32kHz frequency. 170V is good because it's not too high for a 10x probe, but not too low for a 1000x divider.

Here's the result. First, the secondary after rectification and filtering, measured with the regular 1/10 probe. A very acceptable DC signal:

However, here's the same signal measured with the divider. If we ignore the heavy noise, we can see the same pattern seem on the first picture:

I don't know it this is the only problem with my circuit, but it's clear the measuring method is the biggest one. I will build a 1/1000 probe, using high voltage resistors and compensation capacitors shielded from noise. I can't rely on simple voltage dividers for this thing.


texts: Simplest octave up (pitch shifter) circuit

texts:
What is simplest circuit to pitch instrument (bass) one (or two) octave(s) up ?
I am asking for this because there are no electronic shops where i live, and getting parts, especially chips is pretty hard, you can not even get 555 timer chip over here, all i have at hand is PC power supply and random board, most probably volume control, from soviet TV, i heard that diode bridge rectifier can double the frequency because output from guitar is AC and when it is converted to pulsing DC, frequency of this pulsing DC will be 2x higher, is this true ?
tl;dr i want to make simple octave up stompbox for bass guitar, quality is non issue


texts: Equipment Grounding Conductors (EGC) Behavior of Autotransformers

texts:
I'm a bit surprised why some people in the US were alarmed about using autotransformers as general appliance 240v-120v step down transformers.

In Asia where we use 240v. All 240v-120v transformer uses autotransformer design to produce less winding and cheaper. In the following you can obviously measure conduction between one of the leads of the primary and secondary (whereas in a real Isolation Transformer which I also have. There is no conduction between any primary and secondary leads).

My question is. You use Equipment Grounding Conductor (EGC) on appliances so the breaker can trip when hot wire touches the metal enclosure.

How about if an appliance has one hot wire of the secondary of autotransformer touching its metal chassis? This won't trip the main breaker because it's located on the primary panel and there is the winding inductive blocking the overcurrent, right?

So how do you properly put EGC on secondary side of autotransformer to make sure the breaker would trip when secondary hot wire touches metal chassis? Maybe a separate breaker in the unit itself? For a 500va autotransformer like the above. What must be the unit breaker or fuse so it would trip on secondary hot wires touches metal chassis?

Some of my circuits were powered by autotransformer hence I want to understand the EGC behavior of autotransformers.


texts:
I have a need where I want to control 24 individual LED array connected through TLC5940 & CAT4101 LED driver.

I have 144 LED's in 24X6 LED array. These are high power 3W LED's. After searching I found out that TLC5940 can be used to increase the PWM pin's on Arduino.

I'm not sure how to connect TLC's output to CAT's input. Since the TLC is current sinking driver how can I use it to control LED brightness by sending signal to the PWM Pin of the CAT? If I connect TLC's output to CAT's PWM input will it work?


texts:
I have a problem with downloading the .hex file to PIC18F97J60 using PICKit2. The software I'm using is MikroC when I'm trying to send the file it shows me:

  (warning: Some configuration words not in hex file. Ensure default values above right are acceptable)

Does anyone know how to tackle this issue, and what is the configuration needed?
I'm very sure about the pins connection for (VDD, VSS, ENVREG, VDDCORE/VCAP, and MCLR). This is the first time trying to program it.


texts: How to break this ground loop in my car?

texts:
Here's the schematic for my car:

simulate this circuit – Schematic created using CircuitLab

The head unit is referenced to car's chassis. My amplifier and DSP are in the trunk. The DSP has an isolated DC/DC converter. And the amplifier internally connects signal ground to the chassis. This form a massive ground loop from the head unit through the RCA cables through the ground connection in the amplifier through the car's body back to the head unit. This has been a source of whine and noise.

I know about the ground loop isolator transformers, but those usually introduce a huge amount of distortion and dirty up the sound.

Other than a transformer in the way of the signal, what are some ways I can break this ground loop?

I am designing the DSP, so I have full control over how it manages the ground. It consists of an ADC daughter board, a DSP board, and 2 DAC boards. All the ground connections in the DSP are connected together, but I have the ability to change that. I thought about opto-coupling the i2s signal coming out of ADC, but I'm not sure if that's a good way.


texts: Learning how to read schematics, questions about fractional voltage in schematic

texts:
In a schematic I've been reviewing I see in only one spot that there is a 1/2v going somewhere? What does that mean?

simulate this circuit – Schematic created using CircuitLab


texts: This is a transformer that puts out 13vdc.It has a built in bridge. There are three taps on the primary, which ones connect to a/c?  this is going to power a dc motor. Thanks for your help


texts: Designing a parallel, rechargeable circuit out of 18650s

texts:
as my title says, I would like to design a rechargeable circuit made out of 18650s in parallel. I understand that placing batteries in parallel isn't ideal, so my question is:

If I utilize same batteries, with the same age, and allow them to discharge while connected to each other with a resistor to achieve the same voltage, before using them daily (discharge and recharge) is this safe? I see laptop batteries using 18650s in parallel, so I was wondering how did they achieve this safely.


texts: Start ESP (Wemos D1) for short amount of time by pressing a button (no deep sleep)

texts:
How can I let an Wemos D1 boot on a button click, letting it execute an action and then shut down. I would like it to be wireless so it can be very flexible, and would love to not have to worry about it's battery life for about half a year.

I was thinking about making a circuit where the button would complete the circuit and power the Wemos. The problem is that you need to keep the button pressed until the action is done, not so handy.

I was also thinking about having capacitors to store enough the energy after a press for the Wemos D1 to do the action, but this will probably not suffice.

I was also thinking about having a battery in it, putting it in deep sleep and let it wake when needed, but that will make me charge the battery way too much.

Any ideas what I can do?


texts:
I was wondering about this board Im reviewing. Theres a switching power supply module in this board (red rectangle).
switching power supply used: https://pt.aliexpress.com/item/220-v-a-3-3-v-5-9-12-15-24-24-2-6-w-3/32853634328.html?
So was added (Conn_WallSocket) not by me, but I was thinking if is correct or follow good PCB practices route 2 phase from AC network on different layers: Neutral on bottom and 220V on top layer? Well, thers 40 mil width track, its for current from AC Network around 10-15A I think so sounds ok. Anyway, if someone see improvements to do on this route let me know. Thanks.


texts: How to effectively tackle long page write in EEPROM

texts:
I'm using C18 compiler and 24LC256 EEPROM. I would like to know how to handle Rollover case in terms of large EEPROM write.I'm writing a Routine that writes 120 Bytes every half an hour and i would like to know how can i save/store my data easily as Page Write will take only 5 ms as equal to a single write operation.The Page size here is 64 Bytes.And i have to write for 10 hours making it 2.4 K space per day.

Well the problem i have is:

1.I want to use Page Write Efficiently and wants to prevent Roll over condition.
 page size starts from 0-63 , 64-127 ,128-191,192-255...up to 32 K.
 I want to  Predict when is the Page Limit coming and wants the Page Write to shift     accordingly.

eg:
If i start with 0th address: 0-63 will occupy 64 bytes and 64-117 will occupy the next 56 Bytes.
Then for the next Page Write i can only write 20 locations and have to write 64  and 20 in another two Page Write Operations.

Note:Dedicating starting Page Locations for each Page Write is not required.

Page write operations are limited to writing
bytes within a single physical page,
regardless of the number of bytes actually
being written. Physical page boundaries
start at addresses that are integer
multiples of the page buffer size (or ‘page
size’) and end at addresses that are
integer multiples of [page size - 1]. If a
Page Write command attempts to write
across a physical page boundary, the
result is that the data wraps around to the
beginning of the current page (overwriting
data previously stored there), instead of
being written to the next page, as might be
expected. It is, therefore, necessary for the
application software to prevent page write
operations that would attempt to cross a
page boundary

I have been trying to find an algorithm to do so. It would be extremely helpful if you sort out this issue or suggest your insights.

Regards

Arookie


texts: Voltage drop (stop-start) impacting car DVR/dashcam

texts:
My scenario is simple. I have a 12V to 5V inline USB convertor powering a dashcam/dvr. However, the circuit of the car I'm using to power it isn't clean enough, especially with the car's stop-start function (the cig lighter is fine but gives me unsightly cables everywhere).

Looking at this
How do I create a USB cable with a capacitor in-line?

Someone there suggested the formula for calculating the size of capacitor needed.

So assuming the car has 12V feeding it, I could hopefully handle a few volts drop (say 2V) for ~ 1 second. Assuming the DVR consumes 500ma.

This gives me a fairly large 0.25F capacitor. Can someone please correct my maths.

Also when I check the 12V to 5V USB, they've provided solder points on both sides of the circuit board. So I could put the capacitor on the 12V or the 5V side - or both. Can someone clue me in what's the problem with each approach? Will the discharge rush cause my DVR to become unhappy on the 5V side? Will the capacitor upset the car's internal gadgets if I put it on the 12V side (fault codes and what not).

Thanks


texts: Difference in current transformers conection for ground fault detection

texts:
I have seen that for detecting ground faults on a 3-phase system powered by a secondary wye connected transformer, current transformers (CTs) can be connected in several ways:

On the ground connection of a grounded system

Can be installed in a way in which all the wires from every phase will pass through its window

A CT can be installed on every phase and residual current is calculated

My questions are:

How are they different? When can they be considered equivalent for ground fault detection?
Would they react differently to the connection of single phase line
to neutral loads?
Is there any advantage/disadvantage of using of using one scheme over the other?


texts: Change operational mode of CAN transceiver

texts:
I have two MCP2515 stand-alone CAN controllers with an SPI interface, two TJA1042 CAN transceivers, and two Arduino Uno boards. As you may know, TJA1042 has two operational modes:

sleep mode
normal mode.

If I want to change the mode of operation of one transceiver from sleep mode to normal mode (wake it up), I should send a wake up pattern waves from the other transceiver over the CAN bus which is in normal mode. For example, one of the wake up patterns is: 5.5 microseconds low, 5.5 microseconds high and again 5.5 microseconds low. Now I don't know how to send these patterns with an Arduino, because MCP2515 has an SPI interface.

I use library: Seeed-Studio/CAN_BUS_Shield

How can I do this?


texts: How to start micro controller using transistor

texts:
I have a RCWL-0516 doppler radar microwave motion sensor module which I want to start using a on/off wireless controller.

When the wireless controller is on, it outputs a 3V continuous signal, while when it is off, it does not output any signal.

Since the RCWL-0516 needs at least 4V to operate, I can not use the 3V output from the wireless controller to start it so I thought of using a N2222A npn transistor as a switch.

For this, I have connected the emitter to ground, the 3V signal from the wireless controller to base and the ground pin from RCWL-0516 to collector while the VIN pin from RCWL-0516 I have connected to +6V.

With this configuration, when the wireless controller sends 3V, the RCWL-0516 is working as it should however when the wireless controller does not send 3V (is off) then the RCWL-0516 module is sending constant high signal to the OUT output.

So it seems that if RCWL-0516 is not connected to ground and is only connected to the +6V from VIN, it will output high to the OUT pin.

So this configuration is not suitable for my project.

Is there a way where I can control only the +6V which is being sent to RCWL-0516 while it is always connected to the ground ? I have tried to connect the VIN of RCWL-0516 to emitter while the GDN pin to ground however it did not work.

I have also tried to use a IRF520 mosfet driver but it seems that the 3V from the wireless module is not able to start the mosfet.


texts: Where can I find good examples of analog insect-like robots?

texts:
Years ago, I saw a program on TV about this guy who spent his free time building analog robots that looked and behaved very much like insects.  I've been trying, without success, to find that or similar information.

Basically, I'm just looking for examples of how complex life-like behavior can arise in a system that has no "smarts", no thoughts, and no stated goals.  It just happens that its component parts cause it to behave in a goal-seeking manner that appears life-like.  Analog robotic insects seem like a great example of that type of phenomenon.

If anyone can point me to information about analog insect-like robots, that would be excellent.

If anyone can guess the specific TV program I'm talking about, that would be even cooler!


texts: Can we transmit FM signal using AM band and AM signal using FM band?

texts: What I am asking is if it is possible to transmit a frequency modulated wave in AM range(550-1650 Khz) and similarly to transmit an Amplitude modulated wave in FM band (88-108 Mhz).  I would like to know about the technical aspects of the problem like what problems we may face if try to do so.


texts:
I have a 50 ohm BNC cable which connects to a coaxial connector on a PCB.

I want to invert the signal from the cable with an op amp.

If I use the top circuit from the image, will the cable be terminated correctly, or should I add a buffer with high input impedance like the circuit in the bottom of the image to achieve 50 ohm termination ?


texts: Diode marking code KE OB, what could that diode be?

texts: I need the datasheet of this diode. The code written is KE OB or could be KE 0B.


texts: Why I2C designed to work with pull-up resistors and not pull-down ones?

texts:
I understand that in I2C, SCL and SDA lines use pull-up resistors and the pin drivers are open collector NPN devices which can drive pins to ground. This gives I2C an advantage that the same bus now can be shared with multiple slaves, and even if two or more slaves accidentally try to drive the bus at the same time it won't cause any damage to the system.

But this can also be done using PNP open drain drivers and pull-down resistors on SDA and SCL lines. Things like clock-stretching and multi-master arbitration can be achieved with this too.

Does the current implementation of I2C protocol gives any benefits over the above suggested alternative implementation?


texts: Opamp detection of extremely tiny voltage

texts:
I am working on a project that requires measuring absorbance of a solution.

The circuit consist of an emitter led, a photodiode attached to an opamp with \$10^7\$ gain (TIA).
The solution absorbs light from the led and causes different voltages corresponding to different concentrations.  This works well for large concentration solution.

For example the voltage obtained with solution of:

0 mol/l (no solute) is 9.95V
100 micromol/l is 8.92V

But for concentrations <=5 micromol/l the voltage is also 9.95V, which indicates that the change in voltage is so small that I cannot measure it.

How can I improve sensitivity? I considered increasing the gain, but it can lead to a maximum of 100V detected. An opamp's saturation is around +/-15V.


texts: Transistor KSP44 with Ic(max) 300mA can I use it for 150mA

texts:
I have some problems to understand the datasheet of the transistor KSP44 (and transistor in general).

I need to control a LED strip. I want to switch it up through a transistor NPN. My transistor will be triggered by an Arduino, so I can apply maximum 20mA on the BASE of the transistor.

I have looked for a transistor, and I have found the KSP44.

I see on its Maximum Rating values that it can sink max 300mA on the COLLECTOR pin, and to switch, on my LED strip I need 150mA.

Where I have a doubted is about the Electrical Characteristics table of the datasheet. The maximum current in a saturated state of the transistor is 50mA. So could you tell me?

Can I use this transistor to sink 150mA on the COLLECTOR pin?

Thank you much.


texts: What kind of power supply can power this stepper motor connected to an Arduino?

texts:
Stepper Bipolar circut: http://arduino.cc/en/Reference/StepperBipolarCircuit

I have this bipolar stepper motor "Stepper motor - 200 steps/rev, 12V 350mA - " which i am connecting to an Arduino. The ardunio as i understand can only deliver 5 volts of power, so its not enought for the stepper. Based on this circut, what kind of power supply do i need to power the motor?  Can i just connect the GND of the h-bridge and NPN transistors to a 12v ordninary house hold battery? What is the difference in having an external power supply and just connecting a ordinary battery directly?


texts: Why cannot there be several energy sources and consumers in different places in a DC network?

texts:
On German Wikipedia, I found the following:

  Im Gegensatz zu Gleichstromnetzen können Wechselspannungsnetze und somit auch Dreiphasensysteme als vermaschte Netze oder als Verbundnetz betrieben werden, wo mehrere Stromerzeuger an verschiedenen Punkten des Netzes Energie einspeisen und an unterschiedlichen Punkten elektrische Energie für die Verbraucher entnommen wird.

Translation:

In contrast to direct current networks, alternating voltage networks and thus also three-phase systems can be operated as meshed networks or as a compound network, where a plurality of power generators feed energy at different points in the network and electrical energy is collected at different points for the consumers.

I understand that “in contrast to” means, that in a (hypothetical) DC network, it is not possible to have several energy sources (power plants) and consumers in different places. Why doesn’t this work if you have DC, but it works using AC?

An example:

What happens in the DC network? A short circuit?


texts: What does the % symbol mean on plc addresses?

texts:
I've seen contacts assigned with a % symbol on ladder diagrams and plc structured text. For example a normally open start button would be %I1.02 and a coil would be %Q5.3
I understand the I and Q is input and output, respectively... But what is the % symbol for?

Any information on this will be appreciated.


texts:
I would like to extend the maximum DeepSleep time of my ESP8266 12 F Module (running the Arduino ESP8266 Firmware) to 4 hours. I just found out that the maximum Deepsleep time is 71 minutes:

I found this short description on this Site:

  One common way to extend the deep sleep time is to maintain a counter in NVM (i.e., Flash or RTC Memory), and increment the counter each time that the device wakes up. If it reaches a certain threshold, then do the work, otherwise go back to sleep.

So I'm trying to understand how this should work?
After Deep Sleep, the ESP8266 12 F module starts again at the Setup.
I know that:

bool rtcUserMemoryRead(uint32_t offset, uint32_t *data, size_t size);
bool rtcUserMemoryWrite(uint32_t offset, uint32_t *data, size_t size);

reads and writes stuff to the RTC Memory but I am not sure how to get a counter ready so that the Module goes into deep sleep 4*3600 seconds (so 4 Hours):

const int sleepTimeS = 3600;//1 Hour (3600 seconds)
void loop() {
do somehting;
ESP.deepSleep(sleepTimeS * 1000000,WAKE_RF_DEFAULT);
}

How would I position everything so that the code runs on boot up and than goes into deep sleep for 4 hours?

DigitalNinjas post did it, I had to make 2 adjustments. Here's the version that worked for me:

// NVM Data
#define RTCMemOffset 10 // arbitrary location
#define MAGIC_NUMBER 55 // used to know if the memory is good and been written to

    struct
    {
int wakeCount;
bool bFirstTime;
int magicNumber;
    } nvmData;

    nvmData sleepMemory;

    bool bDoneSleeping;

    void setup()
    {
/* Woke up and entered setup */
bDoneSleeping = false;

if(ESP.rtcUserMemoryRead((uint32_t)RTCMemOffset, (uint32_t*) &sleepMemory, sizeof(sleepMemory)))// EDIT: ESP. was missing
{
    if(sleepMemory.magicNumber != MAGIC_NUMBER) // memory got corrupt or this is the first time
    {
        sleepMemory.bFirstTime = true;
        sleepMemory.magicNumber = MAGIC_NUMBER;
        sleepMemory.wakeCount = 0;
        bDoneSleeping = true;// EDIT: Set bDoneSleeping to true so that the code runs on boot up
    }
    else
    {
        sleepMemory.wakeCount += 1; // incrememnt the sleep counter
        sleepMemory.bFirstTime = false;
    }

    if(sleepMemory.wakeCount >= 4) // reset the counter and do whatever else   you need to do since 4 hours have passed
    {
        sleepMemory.wakeCount = 0;
        bDoneSleeping = true;
    }

   ESP.rtcUserMemoryWrite((uint32_t)RTCMemOffset, (uint32_t*) &sleepMemory, sizeof(sleepMemory)); // write the new values to memory // EDIT: ESP. was missing
}

if(bDoneSleeping)
{
     // Perform tasks
}
else
    // Go back to sleep
    }


texts: Transistors with different loads in parallel

texts:
My circuit roughly looks like this:

I want to send a signal to uC and turn on a LED when there is light shining on phototransistor Q3.
Currently I'm using stm32f4 (discovery board) as a signal receiver, but I would like to be able to replace it with an atmega at any time.

My problem is that base of Q1 is taking almost all of the current coming from Q3 and emitter-ground voltage after Q2 is too low for a uC to recognize it as a logical high.

I know I can add a resistor just before the base of Q1, but I don't know what is a resistance of the input of the uC (because it may be replaced with a different one)

How can I make sure that both the LED and the signal to uC have enough voltage to work properly?


texts:
The component is supposed to be TCA9517DGKR, a level-shifting I2C bus repeater from Texas Instruments. I got these soldered from a turn-key Chinese fab. The top markings are TI43 (Or T143?) first line, and AYK second line:

The AYK is the correct chip mark for TCA9517. However the chip doesn't function as it should, whatsoever. When powered up as TCA9517, it clamps SDA and SCL lines. As a stand-alone, DMM shows no connectivity between any pins.

[The original (good) chip has a clear first-line mark as TI 6B]. More, the chip has some bottom thermal slug:

I suspect the chip is some medium-power transistor, but wasn't able to find a match. I have 250 of these suckers, and if someone can identify the chip, maybe I can re-use them in some other projects.


texts: design considerations of Ethernet-spi controller

texts:
Recently I have designed  board on which Ethernet and gsm module need to be placed. Already I have exported Ethernet related chip to pcb and arranged in this order s shown in below image
This is how I placed U10 (Ethernet-spi controller), U9(magnetics) ,J2 (RJ45).Whether this plcmnt is correct??
This complete board is consists 4layers.
Mid-Layer 1 will be power plane.
Mid- Layer 2 will be  ground plane.
One more GSM module need to be placed yet, where I don't have enough  place on top layer  except on below layer ...
My question is....
1.Shall I place gsm below this Ethernet setup..?
2.what are the pros & cons if I place in this Passion.

Is  there any  other  option to place?


texts: Induction meter, finding standard reading

texts:
If I have the time it takes an induction meters disc to complete one revolution, then how can I work out the power in watts ?, I feel like i'm missing some other parameter that is needed

I basically have a three phase system with three check wattmeters and an induction meter and am told to find the error of the induction meter by comparing it to the wattmeter readings

Also, Am I right in saying the wattmeters measure real power ?, example, for 0.8 lagging pf, the wattmeter reading would be VI*0.8 ?

And does the induction meter measure apparent power or real power only ?


texts: How do I upload a hex file firmware to a target board without using the arduino IDE?

texts:
Is there a way for me to create an installer that runs a shell script to upload a firmware update to an arduino that doesn't involve using the IDE?  I have a thing that I make that sometimes needs a firmware update, and sometimes the people who would apply the firmware update wouldn't be able to apply the update from the IDE. I'm guessing it's something to do with avrdude, but try as I might to learn how, I just haven't had any luck on my own.

I can handle the "create an installer that runs a shell script" part.


texts: How to Power 2 devices at different voltages with the same set of power source(batteries)

texts:
I'm just curious if it's possible to power 2 devices at different voltages with a set of batteries while making sure that the 2 devices makes use of all the batteries. I have here an illustration of the connection that I would like to get verified.

Each battery is rated n volts

I used dashed lines in 2n volts connection for ease of seeing.
I want to power each device with 4n volts and 2n volts

An Alternative Illustration^

The solution that I propose is to connect 4 batteries in series first to power 1 device. Then since there can be 2 sets of batteries in series already I can connect these sets in parallel for the Voltage to not add up. However, just by looking at  the circuit I think some portions are actually shorted.

Any help would be appreciated. Please don't be  harsh if this is a dumb question.


texts: What's the use of the ground socket of an ungrounded GFCI receptacle?

texts:
Is the ground socket of a GFCI receptacle that isn’t connected to ground useful? (I'm in the United States, if it matters.) If the connected appliance had current on its ground pin, where would this current go in the ungrounded GFCI? If the current on the GFCI's hot and neutral are equal, including the case in which both are zero, will this ground-pin current cause the GFCI to trip and disconnect its internal hot, neutral, and/or ground?
 Which one(s) will it disconnect? Can current on the ground pin keep draining somewhere even after this tripping? If so, does that mean GFCI automatically internally bootlegs/bridges its open ground to neutral under these tripping conditions?

Can the ground socket be used for grounding the following ground-pin-only items?

a shielded ethernet cable's drain wire that's inserted into the
socket via a ground-only
plug,
an ethernet surge protector that uses only the ground pin,
surge protector power strip,
anti-static wrist strap


texts:
Thank you all, let me ask about schematic design A Class Amplifier schematic on internet, explain to me about how much voltage amplifier the design? 10x times or 100x times, and how we calculate the 10-14 watt power?
please explain step by step, thank you very much


texts: boost converter for ultra low power application

texts:
I want to design a dc-dc boost converter and manage power (MPPT) for an ultra-low power fuel which contains input voltage < 1 V and input current < 500 uA.
if I choose simple boost converter, I will have problem with inductor design because low input current (about 500 uA) will cause extremely high inductor.

Here is the formula for calculating inductor for simple boost converter [L= (Vin*D)/(fs*0.3*iL)]

I need to choose high freq and high L that means an inductor with more than 10 mH inductance and work in 5 MHz freq. (we don't have inductance in this spec)
what should I do for power managing of this ultra-low fuel?


texts:
what happens if I exceed the maximum rating of the drain-to-source voltage of an N-MOSFET
I am using NTNS3C94NZ so 12 V in this case
datasheet:
https://www.onsemi.com/pub/Collateral/NTNS3C94NZ-D.PDF
does it act as a zener? as a short?
is it destructive?
what voltage/current can it handle?

I did the test with 20 V, it seems that the over-voltage on the drain leaks to the gate, enables the transistor, that start conducting and pulls the drain low.
so externally, it did act as a ~14 V Zener Drain-to-Source with 20 mA current (dependent on my voltage supply strength). It seems to be still functional after that as the current was limited.


texts: Circuit design question - low pass filter

texts:
I designed a low pass butterworth filter with the specification to have a 500Hz cut off frequency with diagram as shown:

In the specification it says "Signals need to be attenuated by at least 80dB relative to difference frequency of 400Hz" but I'm not sure what this means?

edit:

the input of filter is a 100mV AC signal, the filtered signal needs to be converted into a 5V signal. I have thought of using this comparator circuit after the output of the filter circuit?


texts:
I need a constant current of 400-500mA for each color of a 10W rgb LED. Each color consists of 3 1W chip is series. for 3 LEDs in series I'll need about 11 Volts for blue and 8 volts for green.
So far I've successfully used lm317 to create a current source. As I'm going to build several of such drivers I'm looking for a better option. As you know LM317 requires about 3V voltage overhead which is not nice at all (I'll have to use 14V power supply which is not standard, and too much heat is generated).
Is there any other IC with lower voltage overhead?
LM317 is so easy to use and adequately precise for my application, Is there any better option?
After some search I found a few IC's form which I found the following appropriate:

1- onsemi NUD4001 datasheet: http://www.onsemi.com/pub_link/Collateral/NUD4001-D.PDF
this one seems very nice but for red color and 12V power supply, the power dissipation of the IC is more than permitted :(

2- onsemi NSM4002MR6 datasheet:http://www.onsemi.com/pub_link/Collateral/NSM4002MR6-D.PDF

I'm not sure about the allowable power dissipation of this IC. This IC is made up of 2 transistors as explaind in How can I efficiently drive an LED? additionally due to dependence of current gain of transistors on temperature how precise do you think these drivers are?

what do you think the best option is?


texts: PV with Arduino and 12Volt Sealed Lead Acid battery

texts:
I have bought this solar charger (Epsolar-LS0512E): https://www.manualslib.com/manual/970886/Epsolar-Ls0512.html#manual
a 12 Volt Sealed Lead Acid battery, and I use this solar panel:

Voltage: 12V
Peak Power: 40 W
Number of Cell: 36 Pcs
Short Circuit Current (Isc): 2.47 A
Open Circuit Voltage (Voc): 21.82 V
Maximum Power Current (Imp): 2.27 A
Maximum PowerVoltage (Vmp): 17.6 V

I want to supply a load, and by reading the solar charger manual it says to use fuses. I use special cable (4mm) for DC current from solar panel to the solar charger. My question is what fuses should I use? Is there any special fuses for PV? Should I take care of something else? It is the 1st time I use PV and I don't know how to proceed...

Thank you!


texts:
Consider a MOSCAP with fixed charge \$Q_f\$ per unit area at oxide-semiconductor interface and non-zero difference between work function of metal and semiconductor. The question is to compute the electric field in the oxide at flatband voltage. One way to tackle this problem is use the fact that the gate voltage is the sum of potential drops across metal(which is zero), oxide and semiconductor. Exploiting the fact that at flatband condition potential drop  across semiconductor is zero, we arrive at the formula
$$
E_{ox}=\frac{V_{fb}}{t_{ox}}.
$$
We can also express flat-band voltage as:
$$
V_{fb}=\phi_{ms}-\frac{Q_{f}}{C_{ox}}.
$$
Thus after further simplifications we arrive at:
$$
E_{ox}=\frac{\phi_{ms}}{t_{ox}}-\frac{Q_f}{K_{ox}\epsilon_{o}}.
$$
However another approach is to use Gauss law. At flat band condition we have charge density and electric field in semiconductor to be zero. Now by using the Guass law to relate the discontinuity in displacement vector in oxide and semiconductor we arrive at
$$
D_{ox}=Q_f.
$$
This simplifies to:
$$
E_{ox}=\frac{Q_f}{K_{ox}\epsilon_{o}}.
$$

  Which method is correct and why is the other method wrong?


texts: interfacing max30100 to 8051(I2C Communication Protocol)

texts:
I'm trying to interface heart beat sensor max30100 to 8051 for this purpose I should use i2c protocol. I'm using the following code for that but the sensor doesn't work even though i do the initializing

    ; Init i2c ports first
    lcall i2cinit
    ; Send start condition
    lcall startc
    ; Send slave address
    mov a,#0AEH
    acall send
    ACALL ACK
    ; after send call Carry flag has ACK bit
    ; If you want to check if send was a
    ; success or failure
    ; Send data
    mov a,#09H
    acall send
    ACALL ACK
    ; Send another data
    mov a,#0FFH
    acall send
    ACALL ACK
    ; Send stop condition
    acall stop

    lcall startc
    ; Send slave address
    mov a,#0AEH
    acall send
    ACALL ACK
    ; after send call Carry flag has ACK bit
    ; If you want to check if send was a
    ; success or failure
    ; Send data
    mov a,#07H
    acall send
    ACALL ACK
    ; Send another data
    mov a,#47H
    acall send
    ACALL ACK
    ; Send stop condition
    acall stop

    lcall startc
    ; Send slave address
    mov a,#0AEH
    acall send
    ACALL ACK
    ; after send call Carry flag has ACK bit
    ; If you want to check if send was a
    ; success or failure
    ; Send data
    mov a,#01H
    acall send
    ACALL ACK
    ; Send another data
    mov a,#0A0H
    acall send
    ACALL ACK
    ; Send stop condition
    acall stop

    SJMP $

    sda equ P0.0
    scl equ P0.1

i2cinit:
    setb sda
    setb scl
    ret

rstart:
      clr scl
     setb sda
     setb scl
     clr sda
     ret

startc:
    setb scl
    clr sda
    clr scl
    ret

stop:
    clr scl
    clr sda
    setb scl
    setb sda
    ret

send:
    mov r7,#08
back:
    clr scl
    rlc a
    mov sda,c
    setb scl
    djnz r7,back
    clr scl
    setb sda
    setb scl
    mov c, sda
    clr scl
    ret

ack:
    clr sda
    setb scl
    clr scl
    setb sda
    ret

nak:
    setb sda
    setb scl
    clr scl
    setb scl
    ret

recv:
    mov r7,#08
back2:
    clr scl
    setb scl
    mov c,sda
    rlc a
    djnz r7,back2
    clr scl
    setb sda
    ret

`


texts: Tips about signal strength metering with percentage

texts:
I'm working with a device that receives digital television signals in the range of -40dBm to -100dBm. My tuner component has some status register that will give me a value for the signal strength, and I can find a lower saturation and an upper saturation value (which would be my 0% and 100% signal strength).

I want to give the user a reliable signal strength feedback based in percentage.

What should I do? Should I map the register value to the signal strength values in dBm or in mW? Which will make more sense in this situation?


texts: Can you bridge or parallel the outputs of the PAM8403 amplifier?

texts:
The PAM8403 is a dual channel amplifier, but I only need one channel. I want to utilise both channels as one, in order to get a single channel with higher output power.

I have been reading through the PAM8403 datasheet, but can't find any hints on whether this was recommended or not.


texts: What's the best (cheap) way of stripping enamel off of magnet wire?

texts:
What is the best way of stripping enamel off of magnet wire using things available in a common electronic setup? I mean, I have some wire cutters and I can use it to strip the enamel off of thicker magnet wire but I have two thin types of wire. For one of them I can burn the enamel off effectively but it still seems to not be consistently conductive. For the thinnest wire I have when I burn it off the copper(I assume it's copper, the wire is of unknown origin) the copper burns and vaporizes with it and the wire just falls apart becomes disconnected.

What's the best way of stripping enamel with common tools? (as in, without special acids and such)


texts: Definition of differential input resistance

texts:
What is a differential input resistance (\$R_{\text{id}}\$) in a differential amplifier? Could you show me the expression for this quantity?

I think it is:

$$R_{id}=\frac{v_{id}}{i_{id}}=\frac{v_{i2}-v_{i1}}{i_{i2}-i_{i1}}$$

I didn't find this expression anywhere, so I need to be sure.

There's an image of a basic differential amplifier: