texts:
I take next sample schematic.

This is only an output stage of any real power amplifier. It's clear when it's work in B-class the every BJT amplify only one half of input signal. But what it means if it works in class A. I know that the  current always go through BJT if it works in class A. And if signal is too small but enough to open the BJT it will amplify both negative and positive signal swings before the signal level achieves some value above that only part of that signal will be amplified with "N" or "P" stage accordigly. Ok, if both parts of small signal amplified with every parts of a power amplifier, how do they added on load resistance? They both must have opposite direction and must differ from each other and the 0 must be on load. Here is a trick that I can't understand. Any suggestions?


texts: Effect of using two buck converters in series

texts:
Are there any limitations of connecting two non-isolated buck converters in series? Just taking the output from the first converter and connect it as the input of a second converter to produce two DC voltages.

I've seen and tried this before but are there any relations between the two switching frequencies that I should avoid or any other parameters?


texts: Can a 30V USB power a 12V light strip safely

texts:
I'm a beginner in this field. I'm  making a desktop LED Sign, for that I'm using a 12V LED Light Strip. I have a standard USB Cable from an old phone charger, it says 30V on the cable, so if I connect that cable to the LED, and power it from a USB port on my PC, will the LED break or get ruined?

Also another question, on the right side, it says +12V so does that make a difference if I power it through a 30V cable?


texts: How to drive external LEDs using Digilent Genesys (Virtex-5) FPGA? How to use pressure or IR sensor input?

texts: How can I drive an FPGA with Digilent Genesys X LEDS with a breadboard and socket 752 DIP?  If the LED of range is zero + 445 and the impedence is 74 what is the range of the flash?  This is for reconfiguring the blocks WITH CLB Verilog and not using a system of linear equations.


texts: Theres a very good explanation for the Boost Converter on Wikipedia. But it is a very mathematical explanation. How would you explain the Boost converter to a non Math person like  me?


texts: How do you calculate the value of the inductor and capacitor in a parallel LC circuit?

texts:
There is a parallel LC circuit with unknown values for the inductor and the capacitor.  How exactly can I identify the value of the inductor and capacitor?

I know I can apply an sinusoidal function to the circuit and calculate the product of LC by identifying the resonance frequency.  However I cannot figure out how exactly one could identify the value of the individual components in the parallel LC circuit.  I can only use an oscilloscope and a signal generator.

Note:  I cannot remove any components from the LC circuit as it is in a "black-box."


texts:
because I want to have PWM dimming LED, I have connected PWM signal to EN pin of TPS63060. I wonder is this correct? According to datasheet chip have soft-start so it shouldn't destroy LED. PWM signal have 180Hz frequency, LED is white 1W power.
Schema:
Simulation:
Green signal is output voltage, blue LED current and red one is EN signal. At start we can see one peak for around 330mA and after that signal is stabilizes to 300mA.
TPS63060 Datasheet


texts: Relation between feedback delay and oscillation of OpAmp

texts:
This is from TI Precision Labs - Op Amps: Stability - Introduction presentation here. He is trying to explain how delay can cause oscillation intuitively from time domain.
This is an exceprt from the presentation:

Too much delay between the amplifier output in the inverting feedback
node is a straightforward way to visualize the root cause of op amp
stability issues. The effects of feedback delay are displayed in this
example by observing the voltages at the amplifier output, Vopa, and
the amplifier inverting input, Vfb, when a step is applied to the
input, Vin. When Vin changes, Vopa responds in an effort to set Vfb
equal to Vin to reestablish the virtual short between the inputs.
However, the feedback delay results in an erroneous voltage at Vopa by
the time Vfb equals Vin at 0 volts. As a result, Vfb continues to rise
and overshoots the input voltage, causing Vopa to reverse directions.
Depending on the severity of the delay, the output may settle, or may
result in a sustained oscillation as shown here.

Can anyone explain the bold part? How the feedback delay causes erroneous voltage at Vopa at that time?
What Vopa is supposed to be if the circuit is working correctly?
In this circuit how can you draw the waveform of Vopa or Vfb?
Because they're inter-related so it's hard to make drawing for oscillation case like that.


texts: How to minimize DC brushed motor arcing noise propagation from MOSFET drain to gate?

texts:
I designed a basic on/off control circuit using 555 timer for a 3v hobby dc motor as shown in below.

Without the motor connected, the output off the 555 timer is as shown below. (the mosfet drain is similar just inverted)

But when I connect a dc brushed motor, I suppose the noise seen when connected to dc motor is because of arcing at the brushes. (Please clarify if I am wrong)

In the above image, channel 1 is connected to 555 output pin and channel 2 is connected to the MOSFET's drain pin.

As seen in the oscilloscope, I see that this noise has propagated from the MOSFET (STP16NF06) drain to gate. Due to with 555 timer switches off & triggers erroneously and so the PWM waveform switching is in microseconds rather than seconds.

I further investigated by testing the following circuit:

When I switch on the gate, the motor runs. But the oscilloscope showed the following noisy waveforms with Channel 1 as Gate voltage and Channel 2 as Drain voltage

Please help me remove this noise. I tried adding adding ceramic 1uf capacitors one at each motor terminal, but didn't help.


texts: Harmonic Balance works, transient does not work!

texts:
I have an oscillator circuit and the harmonic balance simulation shows there is oscillation in Vout:

However, when I run a transient analysis, the results are totally different and show there is no oscillation in my frequency range:

Why is there such a huge difference? Which one is right?
The circuit in the harmonic balance is the following, using the Modified Colpitts Core of the ADS Keysight suite:

The circuit in the transient analysis is the following:


texts:
i have a MEMS mic with digital I2S output. What is the easiest way to test that my microphone communicates right?
No need to verify the sound, i just need to verify on bit level that communication occurs. For example how can i test it with an oscilloscope?

input and outputs are listed:

data sheet: link


texts: What is the purpose of copper planes in a switching power supply?

texts:
I'm looking at including a buck converter to power a 3.3V microcontroller, and I used TI's Power Designer to generate a recommended layout for my parameters.

I noticed that the copper planes are quite large here compared to the footprints of the components involved. I understand the value in having a plane for the ground, since it's a common reference point, but why are there such large areas for the other connections? Is it for heat dissipation, or other reason(s)? (Or am I misunderstanding something about how to read the diagram?)


texts: How is this trackpoint supposed to work?

texts:
I have salvaged a track-point device from an old laptop that ceased working. I couldn't find any information on it in the hardware manual. However, the labels (see below) suggested that I could apply a voltage between VCC and GND, and read out signals from X and Y, so I decided to solder a pin header to it and give it a try:

I tried to apply 5V on the VCC, and found that the X and Y pins would settle at about 2.5V each. However, pushing the track-point in all directions did not have any measurable effect on the voltage on X and Y pins.

Does anybody have any information regarding such device, or ideas of what I could try out to get a response from it?


texts: Problem with mosfet driver circuit/switching

texts:
I have the following driver circuit used for switching very high current n-channel mosfets

Here's their datasheet
https://www.littelfuse.com/~/media/electronics/datasheets/discrete_mosfets/littelfuse_discrete_mosfets_n-channel_trench_gate_ixfn420n10t_datasheet.pdf.pdf )

Here's the circuit that I am trying to build

After trying to build a prototype on a breadboard, I've found that there is no voltage drop across the 1k resistor that is connected to the 2n7000 transistor. As a result, Vgs=0 no matter what the output of the inverter is (High=5 V, Low= 0V). Here's the datasheet of the 2n7000: https://www.onsemi.com/pub/Collateral/NDS7002A-D.PDF

Can anyone tell me what I'm doing wrong with this circuit? I don't think I can ground the source of the 2n70000 because then the driver will share a common ground with the very high current power supply.


texts: How to run raspberry pi compatible mipi csi camera on rock pi 4 b

texts:
I am trying to run a mipi csi camera on a rock pi 4 but I can't figure out how to get it working. I have the rock pi 4b running on Debian (Linux) and the camera is plugged in and the power led is lit.

I have found for raspberry pi you type "sudo raspi-config" in the prompt and it opens configuration settings to enable the camera, but I can't find anything similar to work on the rock pi 4.

How can I get the camera running/taking video or pictures?

Link to camera: https://www.amazon.com/gp/product/B013JWEGJQ/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

To clarify: I am Not using a raspberry pi so raspberry pi documentation does not work. I am using a different single board computer called the Rock pi 4
https://wiki.radxa.com/Rockpi4


texts: Why does the GND of the Arduino oscillating as well?

texts:
I have an Arduino Uno and what it does is simply output an oscillating signal of 1 MHz on PIN11. I measured the signal using a oscilloscope and a probe with a ground clip. First, I connected the probe to a wire which is plugged into PIN11 and the clip to the wire connected to GND. The oscilloscope showed me the expected signal.

Then, I connected the probe to the GND wire and removed the ground clip from the probe while an open wire is plugged into PIN11. The oscilloscope showed me a weakly oscillating signal of 1 MHz. I extended the open wire which is connected to PIN11 and the signal got stronger. Then I removed the wire and the oscillating signal disappeared. My first guess was that the open wire is acting as an antenna.

I also tried to connect the ground clip to the GND while the probe stayed disconnected. Also, an open wire is plugged to PIN11. I expected a weak reversed oscillating signal but the signal was flat.

Now I am not sure again if the weakly oscillating signal is caused by the open wire which I thought it acts as an antenna.


texts: Any problem with this simple supply switching circuit?

texts:
Is there anything wrong with this circuit?

The goal is to have a battery powered device that is occasionally plugged into computer via USB. When plugged into the computer, I want to switch power from the battery to solely USB power. I don't want any battery charging.

This is how I expect the circuit to work:

Q1 is a P Channel MOSFET. It is the switch that connects or disconnects the cathode of the battery from the circuit. With only battery power connected, Q1 gate is 0v and source is 3.6v (from the battery), which drives the MOSFET on and sends power to the load. The diode is to keep from back feeding regulator.

When USB is plugged in, "EN" is pulled to 3.3V which will turn off MOSFET and disconnect battery from the circuit. The regulator steps 5V down to 3.3V and powers the load. There any problems with switching power this way? This is the best circuit I could think of that will have the least parasitic losses and no voltages drops when load is using just battery. It is important the entire system uses no more than 10-15uA. Parasitic losses from this circuit I calculated at about 4.3uA


texts: Can a relay be used for higher voltage lesser current than the rated voltage and current?

texts:
I am in dilemma if I can use a relay(SPDT) with contact rating of 250VAC and 16A to switch 1000VAC and 2A? The switching power is still lesser than the maximum switching power. But I am worried that the high voltage might have adverse effect on relay. Your help will be much appreciated.
Thanks.


texts: How to give a 2-D array as output of a function in Verilog?

texts:
I have to write a code to generate partial products for a 53*53 radix four booth multiplication. I declared a function as shown below; it is showing the error message  MULTIPLE PACKED DIMENSION NOT ALLOWED IN VERILOG. Why?

function[27:0][107:0]boothans;(function declaration)


texts: How do I know if TP4056 charging modules are faulty

texts:
I've bought 10 of TP4056 Lipo charging modules from a Chinese vendor. Tried using them in something I've built, but whenever I plug the power source in, the charge led doesn't light up. In fact it doesn't seem to react at all.

So I googled around and saw I could check it by wiring the module directly to a battery and power source, which I did, but still no reaction from the module.
I'm very much new to this and was wondering if I'm doing something wrong and how to know for sure that I got 10 faulty modules, since I already tested 5 of them the same way with the same results.

Attached are the pics of the module and my testing setup - connected to 18650 battery (- to the flat bottom of it, + to the inset top), and power source (tried both computer USB and iphone charger + wall socket.)


texts: Alternative to Linear Actuators or Linear Actuators with small load limit and 70cm movement

texts:
Are there any Alternative to Linear Actuators which are not as expensive ?

OR Linear Actuators with small load limit (about 20Kg) and 70cm movement ?

Thanks and sorry if this was posted in electrical engineering, because I did not find the mechanical engineering community.


texts: How electric signal is converted to more powerful electricity

texts:
First a little disclaimer: I've a newbie question which is simple, but somehow I can't explain it to myself.
I'm interested in how electrical signals can trigger let's say a movement, which requires much more electricity. Let's say that a controller sets a signal on one of its PINs and this causes some rotation in a motor. The rotation requires much more power, than this signal can provide, so somehow the signal is augmented or boosted. Is this the work of a voltage converter? Can you please explain to me how this mechanism works?
Thanks


texts: What voltage range will I need for my multiplexers?

texts:
I'm trying to make a Fuzz guitar pedal effect (for a guitarist in the bands I play in), and I found this one:

The Fuzz of 1000 Faces

Made by Randy Randofo.

Below is the circuit from that site:

I made already a (big) breadboard setup to mimic the routing using multiplexers (CD4051's, CD4052's and 74HC595's shift registers for controlling including a STM32F103), using LEDs. This works fine.

For the CD4051's and CD4052's I use now for VCC 5 V, and I connect VEE (negative) to ground, which works perfectly for LEDS, as they are switched on with 5V and switched off with 0V, thus no negative voltages.

However, I realized I'm using audio, actually from a guitar pickup, which is +/- some volts. Also as can be seen in the circuit, the power voltage is 9 V.

I am wondering now, what voltage I should use for the VCC and VEE for the multiplexers (CD4051's/CD4052's). If I take the most worst case route, which is 9V -> 10K resistor -> C2 -> 100K Pot -> OUT (looking at the small circuit in the upper right corner, copied below), than when the 100K pot is set to 100 K, the voltage at C2 (and thus Q2 etc), will be close to 9 V, so I expect I need -9 V to +9 V to my multiplexers.

This also is kind of shown in the Fuzz faze description of ElectroSmash Fuzz Face, which shows -8.7 Volts (although resistor values are different and inverted because a germanium AC128 uses negative voltage). See screenshot below.

So can someone confirm (possibly with a bit of explanation), if I should use for my multiplexers VCC +9 V and VEE -9 V?


texts: How are processes evaluated in VHDL if a signal appears/does not appear in a sensitivity list and a nested IF statement?

texts:
In VHDL, are conditional IF statements evaluated when any signal in the process sensitivity list changes, or only if the signals are in the sensitivity list and appear as IF statement arguments?

I want to know if counted below is incremented only when enable, cnt_clk_cur, or cnt_clk_cur change state (assuming the IF statement evaluates true), or when any signal in the sensitivity list changes (and the IF statement evaluates true).

I am new to VHDL, so be nice. Any VHDL simulator recommendations are welcome.

begin

   process(clk, aclr, cnt_clk_last, cnt_clk_cur, cnt_clk, enable)

   begin
      if (aclr = '1') then                -- if aclr set all to zero
         counted <= (Others => '0');      -- clear counter
         cnt_clk_last <= '0';
         cnt_clk_cur <= '0';
      elsif rising_edge(clk) then         -- on an edge increment
         cnt_clk_cur <= cnt_clk_last;
         cnt_clk_last <= cnt_clk;
      if (enable = '1' and cnt_clk_cur = '0' and cnt_clk_last = '1') then
         counted <= counted + '1';        -- increment
      end if;
   end if;
   count <= counted;
   end process;

end behavioral;


texts: What material should be used for large-scale electron emission?

texts: Photocathodes, to my knowledge, are usually used for precise and fast light-detection. But would they also be suited for the sole objective of ionizing the surrounding air? If no, what materials would be more suitable?


texts: PIC16 LP drive level - do I need a damping resistor?

texts:
I'm using a 32kHz crystal oscillator with timer1 on a PIC16F1825 to provide more accurate timing for events (I want to do something every 20 minutes). The crystal circuit looks easy enough to design but I'm not sure whether a resistor is necessary to reduce the drive level. I'm running at 3.0V.

I'm using an ABS25-32.768KHZ-4-T crystal from Abracon as the crystal. It has a CL of 12.5pF. Thus I figure C1 and C2 at 18pF. The problem is Rs. The crystal maximum drive level is specified at 1uW and the ESR is 50k but I cannot figure out if the PIC (in LP mode) will overdrive the crystal if Rs is zero. Can I assume that LP will be the "right level". I've seen a number of circuits where Rs is 100k and a number where it isn't present. Thus my confusion.


texts: Is there a good method for transmitting a syncronization pulse wirelessly to multiple devices?

texts:
I'm working on an object tracking system comprised of 3 cameras. The cameras are up to 50ft apart, and each contains a raspberry pi 4, and an arducam OV9281.
I would like to synchronize the frames captured by these cameras to make triangulation simpler. Specifically I'm planning on using the OV9281 external trigger input.
I would like the sync pulse to be accurate within 100uS between the cameras.
The issue is, that I would like these units to be wireless if possible. The pi's can connect to each other via wifi without issues, but I'm not confident that I can synchronize the pi's with adequate precision over this network, and besides that I will still need some hardware in each box to generate the trigger pulses which will feed into the OV9281s. Again, I don't think the rapsberry pi GPIOs will be accurate enough to generate this pulse directly.
The backup option which I'm considering right now is to use 3.5mm audio cable to carry a sync signal.
What I'd like to do is use simple radio of some sort to transmit periodic pulses which each camera can receive, or receive a signal of this sort that already exists (even indoors).
Does anyone know of a method that could achieve this? I know this could easily be done with a custom radio, but I would like to use radio modules of some sort to keep the complexity down.
Edit: Just to clarify, the sync signal will go directly to the camera external trigger input, it will not go through the pi. I agree the pi would not be accurate enough for that with a regular task-scheduled os.


texts:
Background: I have a small soldered joint on a 500 VDC (0.1 A) lead that's exposed to air. The edges of the joint are fairly ridged and have a few significant edges. In the higher voltage range (40 kV) these edges can potentially cause a loss in current due to the ionization of air. Unfortunately, the joint is at a point that I cannot cover with liquid electrical tape or transformer oil.

Question: Will the current drop due to this exposed joint (the exposed lead and joint measure 2 cm) be significant? How much of a current drop should I expect due to the ionization of air, if any?

EDIT: Here are the picture of the exposed sections. Please note that only the white cable has the 500 VDC, others are just ground or 12 VDC inputs.

The two sections that are exposed to air are the connection to the board and the end section (the part covered in solder). I used a gold US dollar for reference.


texts: How do I connect non-I2C devices to an I2C bus?

texts:
I'm quite new to electronics and just trying to do my first Raspberry Pi based system: one diode, one pressure sensor and LCD 1602 with keypad shield (the one for an Arduino board). The way I'd like to connect all the devices is using I2C (the Raspberry Pi doesn't have much GPIO).

And here  comes the question: How can I possibly connect non-I2C devices to the I2C bus? I heard about different expanders, like the MCP23017, will that solve the problem?


texts: RS-232 Zero (-7V) drops when I connect db9 connectors

texts:
I'm interfacing with a system using RS-232. To communicate, I use MAX2322 for TTL <-> RS-232 to interface with PIC microcontroller and PL2303 for USB <-> RS-232 to interface with PC.

All of the converters I've used, when not connected to the endpoint, have a symmetric signal on TX pin (+-7, +-6, +-10, depends on the converter). When I connect to the endpoint, the TX pin keeps the voltage for level 1 but the voltage for zero rise 2 or 3V (+7 -4, +6 -3, +10 -7).

That's not a problem (the system still works), but I'm trying to understand why that happend.

The communication uses 4 wires (GND, TX, RX and DTE) and exchange data in a 1200bps rate.

Can you help me understand why that happen?


texts: Eagle Freeware - definition of 'signal layers'

texts:
According the the Cadsoft website, Eagle Freeware supports '2 signal layers'.  Am I right that Cadsoft includes power and ground layers in their definition of 'signal layers'?

In other words, am I right that Eagle Freeware doesn't support 2 signal layers, a ground layer and a power layer?


texts: Best way of switching between different resistor/capacitor values in a layout?

texts:
In my project I would like to switch between different resistors/capacitors on the fly, preferably without having to open the containing box around the PCB. Therefore, one idea was to use a jumper (connected via cables) which is placed on top of the box, which then can be used to set the currently active resistor/capacitor.
Are there other alternatives? I would prefer THT approaches, if possible.

The main aim of the circuit is to provide different R/C-constants for an OpAmp, operating at frequencies below 10 kHz. Switching between the different values should be as simple as possible, but still reliable, thus I prefer to avoid options mentioned like the alligator clips. Resistor values will be around 10k-10M, with voltages at +- 15V and currents < 1A. Cap values will be in the range of nF.


texts:
I'm building a device containing a large number of ICs. Now, I'm 99% certain heat won't be an issue. (Considering the volts and amps involved, I doubt you could accurately detect the amount of heat involved.) But, just for argument's sake, how would you go about calculating this stuff?

My first thought was to look at the datasheet. But it doesn't seem to say anywhere "this chip will produce X units of heat in normal operation". (Presumably because there's too many different variables that affect it, so they can't easily come up with a definitive number.)

The only relevant thing I can see is a section on "thermal resistence". If I'm understanding this currently, this is a measure of how quickly any heat generated would be able to escape the casing. (Presumably depending on how hot inside vs how hot outside; it seems to be expressed in units of °C/W.)

Clearly thermal resistence is part of the equation. But without knowing how much heat per second the IC produces in the first place, I'm not sure where to start with this.


texts: I am attempting to repurpose a slim LG K40 fingerprint sensor for a diy project. I am looking for a small breakout board that connects to it, so I may connect wires to the small pins. It is a 10 pin connector (I believe a PFC) I have searched online, but can only find breakout boards for other wire tapes that don't connect. Any tips?


texts: power cable: more strands, or bigger strands?

texts:
I have two types of 4awg wire to chose from to wire an inverter in my jeep.  One of them has about a dozen 20awg wires inside of it, and the other has about 100 super little wires inside of it.  Both are copper.  Which would be the better one to use?

Edit: The strands inside of the large wire are not individually insulated, they are all wrapped in one common insulator.


texts: CAN-BUS line goes bus off state at high temperature(70C°)

texts:
I have a CAN-BUS line communicating at 50kb/s speed. There are only 2 products communicating with each other on the CAN-BUS line. One of these products has the STM32L496RGT MCU (the clock speed of the CAN module (APB1) is 80Mhz.) and the other one has the STM32F072 MCU (the clock speed of the CAN module (APB1) is 16Mhz). STM32L496RGT's CAN prescaler value is 100, time segment 1 value is 13, time segment 2 value is 2 and sample point is 87.5%. STM32F072RB's CAN prescaler value is 20, time segment 1 value is 13, time segment 2 value is 2 and sample point is 87.5%. SN65HVD232 is used as CAN-Bus transceiver in both products. In addition, 120 ohm limiting resistors are added at both ends of the line. I have added the schematic of the CAN-BUS module, which is the same in both my products. The inductance of ACT45B coil at 50kHz is 100uH. The cutoff frequency of my low pass filter is 750kHz.I use split termination as termination type. In addition to these, I add the print circuit layouts of the CAN modules of the products. 5. and 8. legs of the Transciever integrated are not connected legs. The schematic is taken from another version of the product.First one is generally transmitter one. The second one is generally receiver. I also use 1 meter of insulated twisted pair cable.
My problem occurs when the products are operating at 70-75 ° C ambient temperature. I monitor and log the line with kvaser can bus analyzer.As far as I follow from the temperature sensors on the products, even error frames start to occur when they reach 55-60 degrees. However, the TEC register starts to increase by 8 by 8. Even though TEC decreases one by one every time the correct message arrives, the error frames that come continuously make TEC 255.When TEC register is 255, naturally the line bus is off. STM32s have automatic bus off recovery feature. I enabled this feature. Every time TEC register is 255, ABOM (Auto bus off management) puts the line back into transmission. However, because the error frames are constantly coming, the line becomes bus off state again.LEC is bit recessive error in case of this times.
Except for the terminating resistor in the line, I removed all filter elements and tried again, but the same situation occurred.I adjusted the line to many speeds and tried it, and again I encountered the same situation.
Wavelengths are as follows.

What could cause this situation?


texts: Transistor use - Basic fan speed controller

texts:
Someone mentioned to me that they wanted to replace a fan switch with a potentiometer to adjust the fan speed. This seemed a reasonable request, and being eager to learn, I drew up a schematic using a simulator (colour has been used to avoid any confusion).

It went from this:

Switch.

To this:

Potentiometer.

The circuit appeared to work, but got laughed at because, "Running 600mA through a potentiometer is not a good idea." and, "A waste of a good pot."

So I read about it, and (without really finding an explanation as to why) I discovered that a transistor is typically required. This seems weird to me because I was under the impression that transistors were much more sensitive than potentiometers, and easier to ruin.

Anyway, I tried implementing a transistor. No doubt there are better (more sophisticated, more components, etc.) circuits for achieving the same goal, but for now I just wanted to make sure I was using the transistor correctly:

Potentiometer + NPN Transistor.

My understanding is that the potentiometer now controls the transistor, rather than the fans directly. And the transistor is basically like a variable gate between the fans and their power source.

The Result:
Current across the potentiometer has dropped from 600mA to 6mA, but the maximum fan speed/RPM has dropped by ~50%.


texts: Nomenclature for changing characteristic curve

texts:
OK, I'm at a loss for words on this one.  I'm looking for a word or phrase to describe the following situation...

I have an open loop control system that when I apply voltage \$A\$ I get output \$A_1\$.  When I'm at state \$A_1\$ I apply voltage \$B\$ (\$B > A\$) I get output \$B_1\$.  But when I apply voltage \$A\$ again I get output \$A_2\$ (\$A_2 \ne A_1\$).

Edit:
I'm still not sure about hysteresis.  I took some data on the system and attached a graph of what I'm seeing.  The system is a camera with a liquid lens and a voltage source. The blue line represents starting at voltage step 126 and then starting to capture an image at each voltage from 127 to 143.

The red line represents setting the voltage to 144 and then capturing the same image moving from voltage step 143 to 127.

You can see that depending on which way I come from the results are different for the same voltage step.


texts: Do I have to ground my laptop to use the Voltcraft DSO-2020USB Oscilloscope?

texts:
I have an Acer Aspire V5 laptop and I want to connect my Voltcraft DSO-2020USB Oscilloscope to it (as an interface).
The power adapters model is PA-1650-89.
I want to measure some 5V stuff - powered from a battery.
Do I have to ground the oscilloscope? And if so, what is the best way to do it?
Thanks a lot.


texts: How to read and understand a data sheet?

texts:
I have built machine powered by an Arduino running a couple of Step Motors. I am now adding an IR sensor the the machine. For connecting the step motors i have found pretty good guides on the internet on how to connect them to get the Arduino to control them. With this addional IR sensor added i am entering uncharted territory. So my question is how to read this data sheet for the IR sensor TCRT5000 and get an understanding on how to connect the piece to existing project (which output go to ground, 5V and to the controller?)

Here is the data sheet for the product i am planning on adding to my existing project.
http://www.vishay.com/docs/83760/tcrt5000.pdf

How do you work when connecting new unknown products to your existing projects? Do you read that sheet and just know how to connect it, or do you use some kind of program to write a "blue print" of how to connect it?

Like this sheet on how to connect a bipolar step to its driver and to the arduino:

It's a nice blueprint to use for a beginner on how to connect the different pieces together. Do you make your own version of that for a piece you are adding before actually start soldering and connecting it?


texts: 4 bit synchronous counter circuit that counts from 1 to 6

texts:
I'm having trouble answering this question, it is for my laboratory. My online lab sessions only discussed how to answer it briefly.

I am not sure how to go from here, I've filled in the K-map with ones and don't cares just so 1-6 numbers are valid but I am not sure how to make the schematic for this?


texts: Why should we care about Vos or Ib if the opamp already has null adjustment

texts:
Almost every op-amp tutorial I came across online goes in depth with their explanation on input offset voltage and input bias current (and input offset current). Not many I find discuss the null offset pin on the op-amp (or the input offset voltage adjustment range), or if not mentioned at all.
Take the old LM741 for example. Adding together the maximum input offset voltage of 5mV and 200nA input offset current (a mere 2mV for 10k source impedance) is still well within the null offset adjustment range of ±15mV. All I really need is just a good quality, accurate pot to balance the op-amp inputs. So long as the null offset pins is provided, I might as well ignore the offset voltage and current in the data-sheet - just tune the pot!


texts: What is the best way to transmit a very small signal from one side of a house to another, without wires?

texts:
I have no doorbell in my house and would like to be able to answer the door while I'm all the way upstairs in my bedroom blasting music. I imagine I could use an Arduino or similar to create a "silent doorbell". After someone pressed it, a signal would be emitted and then received at another Arduino or similar in my room, which would then trigger a lamp turning on.
What's the easiest way to do this without wires, given that my house has a lot of walls and probably a fair amount of wi-fi interference? What kind of transmitter should I use?


texts: Transmission Line: Converting from impedance to admittance. Why?

texts: If we want to find the input impedance of this given transmission line problem, why is it advantageous to switch the quantities from impedance to admittance?


texts: How to calculate index and tag fields lengths for a cpu cache?

texts:
I study computer engeering notes for a cache memory and I try to understand what determines the length of the index and the tag fields. The first examples is for 64 bits and the second example is for 128 bits and I wonder if the tag field length is just chose arbitrarily or what is the reason for being 28 in the first case and 29 in the second case. In the first case the block size is 8 bytes and in the second case the block size is 16 bytes.

Why is the tag field length only 28 bits in the second case?

Source: http://www.ict.kth.se/courses/IS1500/2012/forel/2012-ce_f8ht.pdf


texts: USB-C connector, plug detection and pull up for disconnect

texts:
According to below circuit:

is the USB_PLUG signal provided properly? I would like to have logical 1 when USB_VBUS is provided (5V) and 0 otherwise,
is the 1k5 pull up resistor properly controlled? I would like to disconnect from host when any of SYS_NRST or USB_PULL is driven low.
What kind of T1, T2 and T3 transistors should I use?


texts:
I wonder, how can I make edge detecting circuit without using any logic IC's, using only transistors & passive components?

I have digital signal with ~15ns fronts on my digital input (5v TTL), and I want to get 20-50ns long pulses(with ~10-20ns transitions) on the front edge of the input pulse.

What I tried to do is capacitor + resistor and then push-pull BJT cascade - I am getting nice front(~15ns), but trialling edge is just terrible (200ns) - capacitor slooooowly discharges...

Probably push-pull cascase I am using (see first answer Prevent high-side BJT saturation) is not very 'digital' - i.e. it's too linear... If there is a way to make more Schmitt-like , probably that would solve this capacitor discharge problem...

Any ideas?


texts: How to run Arduino-on-breadboard at 3.3V and still have USB communication to PC

texts:
I have built an Arduino on a breadboard (using an ATmega328PU) with an 5V FTDI USB controller.

I want to be able to run the Arduino at 3.3V instead of 5V.

It works completely at 5V supplied by the FTDI controller, including USB serial from the Arduino IDE to the FTDI controller.

I am using a voltage regulator to lower the FTDI controller's 5V down to 3.3V (I have checked and its always 3.2-3.4V out) to power the Arduino. Everything works (it can power some 3.3V sensors and run my sketch), except I can't communicate with it over USB serial at all.

I have a 22μf cap between the DTR line and the ATmega's RESET pin and I have a 10k resistor on the ATmega's RESET pin (from tutorials the 328PU needs both for uploading sketches), and it works at 5V.

I have tried an NTE4050 non-buffering inverter to convert between the 3.3V and 5V signalling and it still doesn't work. Has anyone tried that?

For serial monitoring (which doesn't work at 3.3V either) I am running at 115200 baud but I also can't upload sketches which is at a lower baud rate (19200?).


texts:
I am trying to select a 160MHz clock oscillator for my FPGA. The least expensive I found was either LVDS or LVPECL type for this frequency. I used a CMOS type before, so the output of the oscillator was GND to VDD. I wanted to ask if I could use LVDS or LVPECL type in the same configuration as CMOS, that is, by connecting OUTN to GND in order to obtain oscillations GND to VDD? Would I still need the 100 Ohm resistor between the terminals? Why?

Also, why are these oscillators so expensive? Are there alternatives?


texts: What is the difference between high and low frequency IGBTs?

texts:
I would like to know which parameters make the difference between a high frequency IGBT and a low frequency IGBT.

For example, I read the AIKW50N65DF5(15 - 120kHz) datasheet and the AIKW50N60CT(0 - 30kHz) datasheet (both from Infineon) and I find that all the parameteres are similar.

So, what really makes the difference between them? Why an IGBT can work with a frequency that other can not?


texts:
Could anyone tell me please what the component circled is? It have 6 pin / legs, and if it not existed anymore could you please let me know replacement / similarities?

Thanks


texts: Chua's circuit's equilibrium at \$x=y=z=0\$

texts:
The Chua's circuit satisfies the differential equations from Wikipedia.

Clearly, \$x=y=z=0\$ is a solution, but not the solution we see when double scroll appears. Since at \$t=0\$ when we switch on the circuit, \$x,y,z\$ must be all very close to \$0\$, for double scroll to appear, the system must be able to walk away from \$0\$. Therefore, \$0\$ must be an unstable equilibrium if the experiment is successful.

However, whether \$0\$ is an unstable equilibrium or not depends on the parameters. So does it mean that, if the parameters are incorrectly chosen so that \$0\$ is a stable equilibrium, then no double scroll can be observed?


texts: Modify spark igniter circuit for bug zapper functionality?

texts:
I have been doing some research on building my own bug zapper circuits for use in an art project (just for arcing electricity, I'm not killing any bugs), in particular finding a good source for transformers. I have found several companies selling transformer based spark igniter kits which also sell the transformer individually. Looking at the circuit for these spark igniters, I see that the two designs are quite similar in their functionality:
Spark Igniter:

Bug zapper:

Both circuits are based around using a transformer in flyback mode, and feature some sort of transistor based oscillator at the input, which create the AC voltage necessary to build up charge in the transformer coil. In one case this is through a 555 oscillator, in the other it's using the inductance of the extra transformer tap to toggle the transistor on and off.
The difference is mainly at the output. The bug zapper includes a filter network to create a differential DC charge between the two sides of the coil, whereas the spark igniter just has an open circuit. The difference in result is that the bug zapper produces an occasional pop, when the DC large becomes large enough to jump the dielectric gap, whereas the spark igniter produces a continuous stream of electricity at the frequency of the input oscillator.
Would modifying the spark igniter to work as a bug zapper be as simple as adding the output circuitry from the bug zapper, or are there additional factors to take into consideration?
Thanks for your help, this subject is not very well documented online so any information is much appreciated.


texts: Real time digital audio frequency changing device

texts:
I want to make a device, which takes an AC audio signal like a guitar pickup signal, or piano or what have you as input, and changes the pitch using this function:

newFrequency = oldFrequency * 2 ^ ( ( interval - 1 ) / 12 )

oldFrequency is the frequency of current note. Interval is just the number of half-steps from that music note, including that note.
For example:
A note at 110Hz with interval = 13 would be A at 220Hz.
A note at 110Hz with interval = 1 would be A at 110Hz.
A note at 110Hz with interval = 7 would be E at 164.814Hz.

That's the case for any music note. Not only A. By the way, interval CAN take negative number for a lower pitch.

The problem is that we have an audio signal at input. One can play multiple notes or a chord at once. Is that going to be a problem?

I'm new to digital electronics, or electronics at all. I would appreciate if you could just give me keywords and leads, so that I could search, study and do more research. I don't know where to begin at all.

Thanks in advance.


texts: How do I protect SD card against unexpected power failures?

texts:
I am working on a device that uses the Microchip MDDFS library to store data to an SD card. The logger will log data at a maximum rate of 1 entry (56bytes) every minute. The problem is the device may lose power at any time, potentially in the middle of a write sequence.  I am wondering what is the best way to protect my data against corruption.  I have found that if the file is open when the power is lost, all data that was written to the file after the last file-close is lost. I don't know if the same holds true if power is lost in the middle of the write sequence.

Since the write procedure doesn't happen very frequently I could open the file, write the data, and then close the file, every time data is logged. Would this approach damage the sd card over time?

Another approach could be to keep the file open but after every 10 or 50 writes I could close the file and then re-open it.

I could also buffer data in memory, then flush the data occasionally maybe after a kbyte or so.

The last idea I had was, in my circuit, I could add a large capacitor that would provide power to my pic/sd card long enough after the power is disconnected to quickly close the file. The problem with this approach is that the time it takes to close the file and/or save data is very inconsistent. From my understanding, this time can very depending on the current place in a flash page that the file is in.

Anyways, what would you guys suggest?


texts: I took apart an LCD module. How do I fit it back together again?

texts: To repair something, I had to disassemble it. Unfortunately, it had an LCD, and that used an elastomeric connector to connect to the LCD. Now I have an LCD, a PCB, and a spare elastomeric connector. I can occasionally get the LCD to work if I put them together, but it will not stay there, and the connection is very dodgy. Is there an easy fix?


texts:
Most examples I find are for buck converters on a PCB of their own with massive traces. I want to make sure this layout is fine with the planes I'm using(both top and bottom copper pour layers are GND).
 I'm using a low output buck converter on a uC board I'm developing. The board will have USB to UART interface, uC, and 900 MHz radio. Total current draw is expected to be 70-100mAh, supply voltage to the board will be 12-30V. I'll leave out all these parts and just focus on the buck and buck components:

Buck: LT3970EMS-5#PBF (350mAh output max,  600Khz frequency).
Inductor: ASPIAIG-S4035.
R14 is just choosing frequency.
Cap values are on layout.
1uF, 2.2uF, 47uF are Cin.
22uF is Cout.

All are ceramic except the 47uF. It's aluminum obviously. I have this because of what the datasheet says about capacitor transients when this device is powered from a power supply.

The data sheet has a PCB layout guideline that I found confusing. I left the Vin and Vout traces stubbed off as this hasn't been integrated into the circuit yet. I've included a close up on the pins so you guys can see the pin names. Thanks!


texts: How can I go about learning to output audio to a speaker using a STM32 board?

texts:
I am hoping someone can point me in the right direction. I am trying to learn how to output audio on a STM32 board. The board I have is the STM32F746ZG NUCLEO board.
I have small (1-3) second audio files I have stored on the internal flash of my STM32, so there is no external SD card or anything. They have 16 bit data @44.1kHz. I was able to convert to 8bit so I tried both 8 and 16 bit. I plan to output the audio to a PAM8302a amplifier which is connected to a speaker. I was following along with the AN3126 (Waveform generation using DAC). I was able to successfully generate waveforms and view them on my oscilloscope. But when I send audio data, it's just static. I tried to follow along this video, but it just sounds like static for the most part with a hint of sound in the background. Not sure what I'm doing wrong but I feel this is not the way to go about this.
So does anyone know what I should be using on the board or reading on? I see SAI, I2S, SPI, etc and honestly just don't know where to start. Am I missing components? I'm not interested in filtering and what not at the moment, that's something I feel can come after. I just want to at least be able to output something audible for now.
Thanks
Edit: For the comments asking for the sine wav
uint8_t samples = 100;
void getSineVal(){
    for(int i = 0; i < samples; i++){
        sineVal[i] = (sin(2*i*PI/samples)+1)*((0xFFF+1)/2);
    }
}
getSineVal();
HAL_TIM_Base_Start(&htim6);
HAL_DAC_Start(&hdac, DAC_CHANNEL_1);
HAL_DAC_Start_DMA(&hdac, DAC_CHANNEL_1, sineVal, 100, DAC_ALIGN_12B_R);
// sineVal being the data, 100 being the # of data points

The clock for TIM6 is at 80Mhz. The prescalar is 80-1, the period is 100-1, and the #samples is 100. So 80Mhz/(80 * 100 * 100) = 100Hz.
Here is the picture of the sine wave I generated at 100 Hz

Edit 2: Here is the code I made.
uint8_t *p = (uint8_t *)&audioArray;
... // I didn't paste here but I move the pointer to the data section
      if(HAL_GPIO_ReadPin(GPIOC,GPIO_PIN_13) == GPIO_PIN_SET){
          uint16_t *pp = (uint16_t *)p;
          uint32_t wavBuffer1[512];
          uint32_t wavBuffer2[512];
          flg_dma_done = 1;
          int count = 65536;
          while(count > 0){
              for(int i = 0; i < 512; i++){
                  wavBuffer2[i] = *pp;
                  pp++;
              }
              while(!flg_dma_done){ // check if the flag is done
                  __NOP();
              }
              flg_dma_done = 0; // clear/reset the flag
              count = count - 512; // 512 bytes decrease
              HAL_DAC_Stop_DMA(&hdac, DAC_CHANNEL_1); // Stop the transfer
              HAL_DAC_Start_DMA(&hdac, DAC_CHANNEL_1, (uint32_t*)wavBuffer2, 512, DAC_ALIGN_12B_R); // Start transmission
              for(int i = 0; i < 512; i++){
                  wavBuffer1[i] = pp;
                  pp++;
              }
              while(!flg_dma_done){ // check if the flag is done
                  __NOP();
              }
              flg_dma_done = 0; // Clear/reset the flag
              count = count - 512;
              HAL_DAC_Stop_DMA(&hdac, DAC_CHANNEL_1); // Stop the transfer
              HAL_DAC_Start_DMA(&hdac, DAC_CHANNEL_1, (uint32_t*)wavBuffer1, 512, DAC_ALIGN_12B_R); // Start transmission
          }
      }
...
void HAL_DAC_ConvCpltCallbackCh1(DAC_HandleTypeDef* hdac)
{
    flg_dma_done = 1;
}

Here is an image of the schematic: https://imgur.com/a/EkPwGi1 (Everytime I try to post an image using the image function here, it never works)


texts: Does a USB hub fall under the definition of 'backplane'?

texts: I am just curious if a typical USB hub with a couple ports for devices falls under the definition of a backplane.


texts: Resistor power dissipation when driving optocoupler from ac mains

texts:
I followed this: https://learn.edwinrobotics.com/230v110v-ac-mains-detection-using-arduino-raspberry-pi-and-esp8266-thing/#Step2

With the exception that I used an LTV-814 that doesn't require a bridge rectifier.

The forwards voltage of the optos led is 1.2 (1.4max) and If = 20mA

Give: Power = I^2 * R = (0.020A)2*(390000) = 156 watts

That doesn't make much sense to me. I'm only using a 1 watt resistor so it should have blown up by now, but it doesn't even get hot. What am I missing?

Further, I calculated my own resistor value for the 390k one rather than relying on the schematic I followed in the aforementioned link:

R = (170vpeak - 1.2forwardvoltage) / .020A = 8440 ohm

Is this correct? Should I use this instead of the 390k resistor?

Mains: 120v


texts: Determining the phase margin of a negative series-shunt feedback circuit

texts:
I have been given a transfer function:
\$H(s)={A_0\over (1+s/w_{p_1})(1+s/w_{p_2})}                  \$

With the condition that \$w_{p_1} << w_{p_2}\$

It's designed for this feedback circuit that has a feedback factor \$K \$ that is equal to 0.5

I calculated both of the open and closed-loop gains without considering any capacitor since I do not see any at the circuit? How should I deal with the given poles if there is no large capacitance in the circuit? Should I  make calculations considering the amplifier-inside capacitors? How can I find the phase margin of such as circuit?

Open and closed-loop gains that I have found:
\$A_{open}=g_{m1}(ro_1//(R_1+R_2) \$
\$A_{closed}=A_{open}/(1+0.5A_{open}) \$


texts: Is parallelling inductors a viable solution?

texts: I am doing a space constrained board layout, in terms of surface area. So I found an inductor which is \$15\mbox{ }\mu H\$, \$2.3\mbox{ }A_{RMS}\$. I need about \$3.5\mbox{ }A_{RMS}\$, so I was thinking of paralleling two \$8.2\mbox{ }\mu H\$ (\$2.7\mbox{ }A_{RMS}\$) to get \$16.4\mbox{ }\mu H\$ at \$5.4\mbox{ }A_{RMS}\mbox{ (max)}\$, with each inductor on opposite sides of the board. Is this a viable solution?


texts: Can I solder a plug to the end of my irrigation system power supply?

texts:
I got a new sprinkler head unit that only takes power input from a barrel plug, here is an ebay listing for the transformer it came with. It's 24VAC AC/AC transformer.
Problem is my old head unit was wired with a power supply that had exposed wires to a screw terminal. I have no outlets near my sprinkler unit, and the power supply for the old unit is wired behind the walls. I confirmed that the power supplies are compatible, so I am going to connect the exposed wires to a plug for the new unit.
My only two concerns are:

I can only find "DC" plugs like these, I am going to try them, but does it matter is says they are "DC" when my transformer is AC/AC? It's probably a dumb question.
My old head unit had a screw terminal for ground, do I need to find a plug that takes a ground wire too, or should I ignore the ground wire in this case?


texts: How to read values from a ROM to control a VGA monitor

texts:
first I have to say that I'm still a beginner and learning VHDL so any advice is a lot of help.

What I'm trying to do is control an image in a VGA monitor with an FPGA (Cyclone II), using a .mif file with the bits corresponding to that image and loading them into a ROM, so then I can read the values and show them.

My problem arises when I have to set the ports for the component that I'm using in my code..

architecture aa of VGA is

--some signal declarations here

component RomImage is
port(   address : in std_logic_vector(13 downto 0);
        inclock : in std_logic;
        outclock : in std_logic;
        qrom : out std_logic_vector(23 downto 0)
);
end component;

begin

RomIm : lpm_rom
generic map(lpm_file=>"GameOver.mif",lpm_numwords=>9500, lpm_width=>24, lpm_widthad=>14)
port map(address=>address,inclock=>inclock,outclock=>outclock,q=>qrom);

-- other process and logic

-- Output logic (only red, same for blue and green)

redout(9 downto 7) <= qrom(23 downto 21) when x>=225 and x<=415 and y>=250 and y<=300 else
                      rojo(5 downto 3);

I don't really know what clock I have to use for the inclock and outclock, one of them is to read address and the other for the output q[].
In the design I enter with a 50 MHz clock and then for the VGA clock I divide the frequency to obtain 25 MHz which is the one I need to make the screen work.

I would imagine that the screen sweep has to be synchronized with the frequency at which you have to read the values from the ROM.

Sorry if it's too much code or confusing, I'll try to expand if needed


texts: Can I charge two 6v batteries with a 12v battery charger?

texts:
I have a BatteryMinder 12v trickle charger and two dead 6v "sealed" lead acid batteries. I assume that the 6v "sealed" batteries means that it is just an ordinary flooded battery that has been sealed shut.
Can I charge the two 6v batteries by connecting them in series and that putting the charger leads at both ends?


texts: Why does BLDC Motor Spin Slower with Same Duty Cycle at Higher Frequencies?

texts:
I have an OTS BLDC motor controller as well as one that I just made myself and both seem to be dramatically slower at higher frequencies.  When I look at how much current is being drawn it makes sense, but it does not make sense otherwise.

I have two tests:

20% duty cycle, f_PWM = 3kHz draws about I = 0.8A from power supply, motor spins faster
20% duty cycle, f_PWM = 8kHz draws about I = 0.25A from power supply, motor spins slower

This is particularly bad because I want to drive the motor at f_PWM ~30kHz.

To be honest, these tests were done with my controller which is limited from ever getting to 100% duty cycle so that I will never have any crossover that could lead to shoot-through.  That said, I do NOT think the losses are switching losses (the current is also much lower).

Any ideas or common reasons why?

Thanks in advance

ADDED:
by f_PWM I mean the frequency of the square wave I am sending to the MOSFET gates at each commutation step.  I have not yet attempted speed control but my plan was to adjust this frequency.

I guess I'm not entirely sure of the dead time.  On a single commutation step I:
  1. turn off all square wave outputs
  2. re-map the appropriate outputs according to what the hall effect sensor state is.
     I put the same square wave on the appropriate high and low side transistors
     Additionally, 1.5us before and after the square wave rises and falls, I fill the rest of the period with a square wave on the low-side counterpart of the high-side transistor to re-charge a charge-pump capacitor.  This is necessary because I am using N-Channel MOSFETs on the high-side as well.

I know that's a little sloppy of a description, but please let me know if there's anything I can clarify.


texts: Buck/Boost converter interaction with MCU in sleep mode?

texts: I am trying to design a battery powered remote controller that has the following components, TPS63802 (converter), AP9211 (battery charger/protection), Atmega328 (MCU), NRF24 (transceiver). The following circuit uses a push button to send a signal to the MCU to tell it to go to sleep or turn on. My questions is regarding the small current drawn my the MCU under sleep mode about (5uA-20uA depending on the sleep mode used) and how it effects the boost converter. More specifically will the Boost Converter be able to supply the 3.3v at such small currents and will the output be stable. Also this is my first time designing a battery powered device that doesn't have a physical switch that decouples the battery from the boost converter. Also is such a method recommend or are there better ways.


texts: Field Coil Help - Varnish, cotton, wrapping etc

texts:
I am restoring a 1940s sewing machine. The motor wire war in really bad condition and needed replaying. I take off the wrapping on the coils to solder some new wire. The wrapping that was used was fine black fabric and maybe something else from the first layer of tape, it was very well sealed on the coils.
I would like to re-wrap the field coils but very unsure what I need and what I don't. From what I read online I can use cotton tape? how would I secure it at the end? do I need to use varnish and if so what type? am I missing something that I am not thinking of?


texts: Is this signal reflection or a damaged transmitter?

texts:
This is (an isolated, differential) capture, 1µs/div, of some Profibus communication over about 10m of cable.  The first image is typical for about 90% of packets and seem fine.  Most are +/-5v with slight deviation from device-to-device as they reply with data. Transitions are ok with a little ringing evident:

But this is what happens when one particular Profibus device replies:

This output is complete garbage and generates Profibus errors.  Only from this device... other devices (same bus) work fine.  Which seems to infer that the cable must be ok and that this device can listen just fine, since it does try to reply.
From this capture, is it discernible whether the issue is an open terminator at the device, or a damaged transmitter?  To me, it looks the transition timings are still good but it's swamped in reflections or some crazy additional inductance, leading to peaks as high as +/-10v.  What is going on here?
Edit: suspect device is a Beckhoff brand BK3150 model "PROFIBUS Compact Bus Coupler." There are several, and the others work fine; just one in particular sends garbage. Speed is 1.5Mbaud. Connector is DB-9, such as this.


texts: What could be the function of three components of this surge protector?

texts:
An SPD module has the following circuit diagram:

I'm trying to understand how it functions.

I only know the varistor symbol on the left corner I guess it is a MOV and suppresses transient voltages.

But there are three components there and I'm wondering what each of them functions related to the L, N and E.

For example does the MOV suppress a transient between L and N or L and E? How about the other two components?


texts: What display interfaces do automotive screens use?

texts: For example the screens inside tesla cars, I first think of HDMI, many high end embedded processor boards come with HDMI outputs, but is this connector found in actual mass production or industrial products?


texts:
(Disclaimer: I'm very very new to this, so forgive if my wording isn't correct)
I'm trying to understand how the wiring of arcade buttons work.
I understand how a button like this works (voltage is carried to the input pin):

But I don't understand how a button like this works, where there is no power connection. The button is just connected to the input pin and ground. Does the current come from the input pin itself? But then wouldn't it just go straight through to ground? How does the button actually activate anything?


texts: FPGA and CPU design: Moving from ideal memory to real RAM blocks

texts:
I implemented the single-cycle MIPS design from "Computer Organisation and Design" in Verilog, shown below:

I used my own "ideal" data memory implementation, which asynchronously presents the read data on the output, and writes data on the rising edge of the clock. This neatly works with the rest of my design:

module data_memory(
    input clk,
    input [15:0] address,
    input cs_mem_read,
    input cs_mem_write,
    input [15:0] data_in,
    output [15:0] data_out
);

reg [15:0] memory [63:0];

always @(posedge clk) begin
    if(cs_mem_write)
        memory[internal_address] <= data_in;
end

assign data_out = (cs_mem_read == 1'b1) ? memory[internal_address] : 16'd0;

Now, I want to use the "Embedded Block RAM" modules my FPGA (ice40 HX8K) supports. In the documentation, they are described as both writing on either falling or rising clock edge (which is fine), but they also read synchronously, which I don't know how to make compatible with my design!

The problem is that at the write back stage, which happens with the rising clock edge, the results from the RAM read are required to already be stable, which is just not the case if I only just started reading from the RAM with the rising edge. But I also want this to stay a single-cycle design.

How can I approach this? My idea was to use the falling edge of the clock to perform the read, but I read online that this approach would introduce another clock domain which is regarded as a thing beginners shouldn't do. Additionally, this would fail if the first instruction is a memory read instruction, since no falling edge happens before the first rising edge. How can this be solved?


texts:
I'm making a circuit which requires an adjustable voltage gain (0 - 1).

I thought of using a multiplying DAC (R-2R type) with input voltage connected to its Vref pin. The input code to the DAC shall be adjusted using a micro-controller and once set, the input code loaded into the DAC shall remain unchanged. I expect the transfer function Vo/Vref to remain constant.

Can someone cite the disadvantages of this circuit? I plan to test it in the next couple of days.


texts: Replacing an FT2232 chip with a custom microcontroller?

texts:
I want to make a circuit board having the capability of configuring (not sure if this is the correct term, but burning a VHDL design (svf, pof file generated by Quartus)) into Altera CPLDs and FPGAs from my computer.

I know a couple of ways of doing this. I can use an Altera USB Blaster cable and directly burn the file using Quartus. Another thing I've seen often is generating an pof/svf file from Quartus, and using urJTAG to program the chip via an FT2232 USB-to-JTAG bridge.

I have a few questions here,

Are these the standard ways of configuring Altera chips? Is there any other popular approach?
Is it practical to make my own USB-to-JTAG bridge on an 8051 (or better) microcontroller chip and successfully configure the Altera chip by  a short pyusb script?
Do you recommend approach (2) for any reason besides a good engineering exercise?

(too broad for the answer, but any help appreciated) As a side note, is there any active IRC channel / forum where such ideas are extensively discussed? Also, what's the best place to look for relevant resources for this project?


texts: Protect DC Circuit from too much voltage

texts: How do I protect a 3v DC circuit from being damaged, if someone accidentally plugs in a 12v power supply? The circuit will draw much less than 1 amp.


texts: What are the advantages of recursive prony?

texts:
Suppose I have following signal:

fs = 20;     % Sampling rate [Hz]
Ts = 1/fs;     % Sampling period [s]
duration = 25; % Duration [sec]
t = 0: Ts : duration-Ts; % Time vector
ss1 = (160.74*exp(-0.15*t)).*cos((2*pi*0.5*t));  %signal 1%
ss4 = zeros(1,length(t));  %signal 2%
tz = 0: Ts : 12-Ts;
for i = 1:length(tz)
ss4(i) = 30.54*exp(-0.25*tz(i)).*cos((2*pi*4*tz(i)));
end

xp = ss1+ss4;

My window length is of 10 second. In first 10 second, it has 200 samples and it calculates two frequency i.e. 4 Hz and 2 Hz. In recursive estimation this continues till 240 samples and from 241st sample onward frequency calculation deviates due to mixed samples. For example if one will choose his current window as 41:241 (200 samples or 10 sec) data point then frequency estimation comes out to be .5001 and 4.001 Hz and second value keep on increasing while it should decrease actually. All is happening because of mixed sampling points. Some of them are double frequency components while some are single one as one proceeds. I want to know what was the real motive behind recursive Prony?
If someone needs Prony code please mention. I hope u are aware of this.


texts: What advantages do CRTs still have over more modern display technologies?

texts: Are there any uses for Cathode Ray Tubes in modern world. TVs and Monitors were first, then Oscilloscopes, I am not sure about Radar but are there any applications which will only work with CRTs or which have and edge for CRT use?


texts:
I've built a simple H-bridge circuit with LTSpice:

DirSigA (blue), DirSigB (red) and Vout (green) waveforms:

DirSig A and B are both pulse signals with a Vmax of 5v. I've been tinkering with the circuit for a while but I dont know why im getting Vout the way its shown. Im expecting it to be 12 volts when DirSigA is high and DirSigB is low and then -12v vice versa. Instead Vout turns 12v volts when both input sources are off and dips to around 11.8v when only one input is as oppose to staying 12 but changing sign. What have I done wrong and how do I fix this? Thanks.


texts: Using transistors (or relays) on a 12V 3A pump

texts:
I am trying to use an Arduino Uno to separately control a 12V .5A solenoid, a 12V 1.5A solenoid, and a 12V 3A pump. I am currently using a TIP120 NPN transistor for each one controlled by the 5V output of the Arduino, but the pump transistor is getting hot after only about 30 seconds of runtime.
To reduce the heat, should I put two transistors in parallel and have a limiting resistor after to limit the current flow? As of now the pump is not pumping hard enough and I would like to get more current (?) to make it run harder. I know it can run harder if it gets the required energy. My power supply says that I am only drawing 2.6 A total for all three, (2 solenoids and a pump/motor) which are hooked up in parallel to the 12V supply and it seems to just max out at that, although at 12V, it says on the power supply it can supply 6A.
The solenoid transistors seem to be fine, the only issue I am having is with the pump transistor getting hot and not delivering enough current to make the pump go hard enough.
Questions

Does the current or the voltage drive the motor? Or both?
Would only having 1.5A flow through each transistor to get 3A to the motor be too much current?
Do I need to put a resistor in line with the Arduino signal voltage? (Beta (DC voltage gain) for TIP120 is 1000 on datasheet)
Should I get a bigger transistor? A MOSFET? Which one?
Should I get a relay instead? Which one?


texts: How to calculate secondary RMS current of each winding in multiplre output flyback converter?

texts:
As I am designing multiple output flyback converter and I have confusion in selection of wire gauge of the secondary winding. There are 4 secondary windings and one bias winding. Mode of operation is CCM.
V_out1  48  V
I_out1  1.5 A

V_out2  48  V
I_out2  0.15A

V_out3  25  V
I_out3  0.7 A

V_out4  25  V
I_out4  0.3 A

V_bias  16  V
I_bias  0.05    A

280 V dc input voltage. D_max=0.47, Lprimary=3.1mH, Fsw=65KHz


texts: Usart puzzle giving strange output on tx pins

texts:
I have tried working out  usart peripheral of pic18f26j50 and it found out to be working very well.

This one is for a pic18f26j50 in bread board with observing TX pin while transmitting in a loop.
This one showed maximum voltage of 3.44 v and mean of 2.10 as showed below.It showed constant frequency with a fluctuation of .6Khz from[2.5 khz to 3.1khz]

The next one is done on a pic18f47j53 Pcb board with two usarts and the transmit Tx pin is called in a loop.But i got terrible o/p and i'm posting the image here.

The o/p of the shows very distorting value when observed in a scope.
it showed maximum voltage in a changing range of 2.0-4.4 v and mean voltage in the range of -416mV-2.38V changing abruptly.
The second one have an abrupt change in frequency from 2.6khz to 4khz and some times 9.6 khz too.

Do help me solve this problem if somebody experienced similar things before.

  The code is just setting the usart pins and configuring the baudrate
  and transmitting in a while loop.


texts: I bought an electroplasma lamp from Lave the original, and the lamp is basically a plasma globe.  I took out the circuit within the lamp, and it had a transformer with a sticker FB-DY-200B CB, is that the identification of the transformer because I have searched  FB-DY-200B CB, and I can not find a datasheet for the transformer? I need to identify the pins of the transformer since it has 5 pins, and wire sticking out making it 6 I guess, making it I believe a transformer that has two primary coils, and 1 secondary coil.  The transformer has a thin copper winding which was connected to two pins before I desoldered in order to understand the transformer, but I was still puzzled, on how to identify the pins.  Is there a method to identify the pins of the transformer?


texts: I know that RBO/RBI pins are used to blank leading zeros in a multi-digit display, but I've never used them once. How do they work? I mean If I ground an active low RBI pin, does that automatically blank out the output no matter what number it is displaying or only if the number displayed is zero? When will RBO be active, when output is zero or if RBI is active?


texts: Consequences of leaving unused inputs of clock buffer floating. Alternative: best practice

texts:
I'm using a Si53342-B-GM

Original datasheet download at silabs for the si5334x-series

as a clock buffer.

In some cases I only need to distribute a single clock signal and in some of my cases I only have a single ended input signal.

While the data sheet describes every detail in dealing with single ended input signals it doesn't regarding unused inputs.

I'm pretty sure, ist is not good to leave one input floating even when CLK_SEL is connected to GND permanentely. But I don't have any proof for it.

I have thought about:

Power being wasted when the differential input amplifier is switching often due to erratic input values (CLK1 and /CLK1 might gain very close voltage levels and produce switching when superimposed with HF signals)
As for the same reason as in 1. cross talk may occur and increase jitter on the output.
The input amplifier might even oscillate and produce EMI on the PCB

Did I miss any possibility or can something be ruled out?

My other question is, what's best practice here?

Tie /CLK1 to VDD/2 by connecting it to the same voltage divider as /CLK0 (considering the case of single ended CMOS input) and CLK1 to GND.
Tie both CLK1 and /CLK1 to GND.
Tie CLK1 to GND and /CLK1 to VDD.
Something different...

Note: I'm using the differential input version of this device when dealing with single ended signals as well as with differential signals at the input to reduce the number of different parts in the BOM.


texts:
I need to protect the ADC pin of my PIC18F27K40 from over-voltage and reverse voltage for a 0-10V input measurement.

After searching the web, I found the following solution :

When testing with the following PIC configuration for PIN RB0:
WPUB0=0
TRISB0=1
ANSELB0=1
D1 = D2 = Zener Diode 3.6V 1N4729A.
I have Vrb0 between 1.4 and 1.5 V for Vin between 0 and 1.5 V.

When I take away the 2 diodes, the RB0 voltage works fine.

Can you please help me ? Am I missing something ?


texts:
I'm having a hard time understanding what the real benefit of a folded-cascode is over a simple cascode:

Also, one more question, is there any significance of there being a low-impedance node (source of M1A) at the drain of M1 (Figure (b))? I can see that M1A forms a common-gate stage.


texts: Why does an induction motor work as generator when running at a speed greater than synchronous speed?

texts:
We know that induction motor works as a generator that means they converts the mechanical energy it receives into electrical energy and this energy is received by the stator. For creating its own magnetic field it takes reactive power and supply active power.
I can't understand what is the internal fact of this phenomenon? How does it receive reactive power and supply active power?


texts: Coppers Pours for 4-Layer RF (433MHz) Board?

texts:
I've got a 4-layer prototype transmitter board built that is using a low-speed MCU (2 MHz).  The critical RF sections are 50 ohm impedance matched to the board's characteristics. I eliminated the GND plane under the antenna and did some via shielding.

The board is just a traditional 4 layer stackup. Top Layer | GND | VDD | Bottom Layer. So in the first run of the board, signals are traced on the outer layers, and then I used vias to connect to the GND & VDD layers. I did not use any copper pours on any outer layer.

Overall the signal strength of my prototype board vs. the manufacturer demo module is largely the same.

However, the TX board is going to go into an enclosure so any increase in transmission strength from board layout is going to be a benefit.

I've got to do another turn of the board for some layout corrections, and I can't decide if it is worth flooding the outer layers with copper pours.

On one hand, you have the potential EMI reduction benefits.  I've had the board FCC tested at a qualified lab for Part 15, but not for any applicable EMI type testing yet.  I'm assuming I am compliant...  if not, okay sure copper pours. But that is not my main concern.

At 433 MHz, antenna manufacturers (Linx Technologies) specify 6 inches by 6 inches for an "ideal" GND plane for a 1/4 wavelength antenna.  Clearly, I don't have that kind of space on my board.

As this is a cheap consumer product, we are using low cost metal helical antennas.  If you examine one of these antennas with a VNA, they do not have great center frequency responses (+/- a few MHZ) and have pretty poor SWR across 433mhz.  The upside -- they are cheap and compact.  Any increased antenna performance, I could eek out with a board change is basically just low hanging fruit.

Do you "get" a larger GND plane by flooding the outer layer with a GND plane and then tying it with vias back to the GND plane?  Would you get some benefit there for better antenna performance with a larger GND plane?

On the other hand, I've read that a copper pour on the outer layers can influence trace impedance? The TX IC I am using, comes with a matching network to turn the TX output signal to 50ohms.  If you adjusted the trace impedance with the copper pour, the IC manufacturer does not provide details on their TX IC & matching network where you could easily readjust their matching network. So that seems like a potential source of signal attenuation.

Also on the negative side, I've read there is a potential for creating antennas for stray pieces of the GND plane that aren't tied through vias.  Assuming you know what you are doing, you can control for this and tie all the copper back to the internal GND plane with vias?

I read one ATMEL app note, and they noted copper pours on 4-layer RF boards as questionable practice for anything but EMI purposes. In their example they put a copper pour on the top layer with all the RF comoponents and traces, and then just loaded up the board with via stiching (30mil pattern) wherever the copper pour was present.

Is there anyone here who has built a 4 layer RF board, who has ever seen a performance boost by implementing GND pours on both outer layers?

Most application notes typically infer a user is using a 2 layer board, where the benefits are more clear.  I've seen this debated each way, and am wondering if someone can speak from experience with a RF 4-layer board?


texts: I can't find the SMT type option in EasyEDA. Is it a new update or I messed up something? And what is a paste type? Please someone help me on getting the SMT type option back. There is no resource related to it on google, so I have asked here.


texts: MW versus MWh is one total capacity and the other maximum output?

texts:
I still don't completely understand MW versus MWh, I have been working on a Wikipedia article for Tesla's "megapack" battery which are measured in both.

I assumed one was an indication of how much power it could dump at any one time and the other the total amount of power stored.

For example one the applications for a backup powersupply for trainlines where it needs to dump a huge amount of power of a relatively short amount of time so as to get trains to platforms during a blackout.

So I assumed 7MWh was the amount it could pump out in any one time and 4.2MW was the amount of power it stored in total, am I wrong?

I want to put a simple explanation in the article.

https://en.wikipedia.org/wiki/Tesla_Megapack#Examples_of_installed_Powerpack_and_Megapack_systems


texts:
I have an Arduino UNO board, and I wanted to design a simple 'sensor shield' --since all simple sensors has 3 pins (namely, SIG-5V-GND) and it is convenient to connect bunch of them directly-- and thats where things got ugly.

Below you can see my very basic design,

As you can imagine, there is 'a-lot' of noise going on right know (with 1 IR range and 3 ultrasonic sensors). I've managed to reduce some of the misreadings on the software side, yet it is clear that I have to make some hardware modifications as well.

A lot of people that had similiar problems advise coupling each additional IC with a 100nF cap.

My question is;

Should I de-couple each line with its own 100nF cap, or is there a neater solution ?
Also, these sensors are connected to my arduino with a 15-20cm cable (physical design restrictions). Because of this, should I take extra measures as well ?

EDIT: Sensors that I'm using

HC-SF04 Ultrasonic Range Finder
Sharp IR Range Finder 10 cm


texts: Can an inductor lose its characteristics permanently after short saturation?

texts:
I was testing a SMPS (boost) where I had an overcurrent due to overload for a few seconds.

The inductor saturation current is 2A.

Although I could not measure the current, I am quite sure that the current was a few times higher than the saturation current.

I was able to switch off everything within a few seconds.

After that I removed the load and the converter works fine under no load.

However, when I connected a load which was previously working fine, the converter is not able to deliver the current and goes crazy.

Basically same behaviour as in the "failure/overcurrent" case.

I checked and inspected all the components, they look fine.

So based on this my hypothesis would be that the short "failure/overcurrent" has changed the inductor characteristics. In particular the saturation current has lowered.

I could not find any information online whether this is physically possible.
Is there anyone who can shed some light on this?

(I am using a shielded  SMD box inductor.)

BTW: Unfortunately, I don't have an LCR meter to measure the inductance.


texts: Altium Designer - Selecting multiple designators in SCH and moving causes an error

texts: When I select multiple designators in the SCH and try to move them via mouse cursor, the designators suddenly shifts to the right, and my cursor teleports to the bottom left of the screen. However I can move individual designators and multiple components just fine. Why is this happening?


texts:
I am designing a connector to PCB interface using a flex-circuit.  Stackup is R-F775 2-layers with plated thru-holes and stiffeners (though the area in question has only traces).  I'm wondering if it is better from a reliability standpoint for traces on either side of the board to be opposing one another or alternating?  The PCB will not see continuous flexing but will be used in a high vibration environment.  I'm not concerned with impedance issues in this application, I'm purely asking about mechanical reliability of the copper.

Opposing:

Alternating:

Thanks!


texts:
I have a problem in buck regulator. I'm using L4970A to make a buck regulator with a variable output that can be adjusted using a potentiometer.

Output is becoming a ramp when I set the output voltage to be above 7 V; it goes up directly and slowly goes down to 7.5 V, and repeated again.

I'm using an inductor that is larger than it should be, my calculation is about 50 to 150 uH, but I use 11 mH. Is that the problem?

This is my design, the same I saw from this application note, pg.38

This is output voltage below 7 V

This is output voltage above 7 V

Could you know what my problem is???
Thanks a lot!!!

Edit 1

I've changed the inductor value to 200 uH, and I tried it to supply laptop with supply input 24 V. It charged the laptop when the laptop was turned on, although the voltage is not stable when I saw it in oscilloscope, but when I turned it off, it won't charge...

Anybody could tell me why it was happen???


texts: strstr function strange behaviour in PIC18F

texts:
I am using PIC18F2520 and C18 compiler. I am trying to communicate with SIM900. I am using interrupt for receiving data. So when I am sending AT+CMGF? SIM900 response with +CMGF=1. I am storing this data in a buffer inside ISR and then calling a function to check.

void rx_handler(void)
{
  Rx[k] = ReadUSART();   //read byte and save it in Rx

  if(Rx[k]=='\r')        //if carriage return is received, stop reading
  {
     LATCbits.LATC2=1;   // turn on led to indicate we have received everything

     process();         // call function to check the received data
  }
  k++;                   //increment k
}

void process()
{
  if(strstr(Rx,"+CMGF:") != NULL)  //if rx data contains +CMGF
  {
     UARTSend("Data Match");
  }
  else
  {
    UARTSend("Data not found");
  }

  memset(Rx,0,sizeof(Rx);    //clear Rx
}

The problem I am facing is it doesnt match the data. But when I pause the debugger and see the contents of Rx, it shows +CMGF: 1. I don't know why strstr function not working. I can also check each byte one by one but that would be very lengthy process. Can anyone please tell me the error. Please help.


texts: What is the advantages/disadvantages of the SMB connector against SMA?

texts:
I would like to connect an external UMTS antenna to the module, because of this I need a 15m long cable. The antenna has N-connector and I have to decide which connector should I put in the other side of the cable. I found only SMB connectors(Bulgin) which rating is IP67. The rating is important because the antenna is connected to an outdoor measurement system. Does it has any disadvantage of this connector in the 1800-2200Mhz frequency range?

I have the following concept:

N(antenna)--------------SMB(IP67, connection to the box)------SMA(Module)


texts: Is it possible to program ESP8266 from another microcontroller?

texts:
I am using PL2303 USB to TTL adapter to program ESP8266, but I do not want to unplug it from system and plug it into PL2303 all the time. That's why I want to program it in system, with my AVR (the AVR is already connected to ESP8266 in the device that I intended to build).

What I want to achieve is that I just restart ESP8266 in flash mode (by hand. It is not a big deal, I can do it myself) and program it using AVR.

I could not ask a clearer question, because I couldn't think of any close solution. Please tolerate my confusion.

NOTE: Uploading a code to AVR which makes AVR act like USB to TTL adapter can be an option for me. That way, I can upload the code I wrote for ESP8266 through AVR.

NOTE 2: I am seeking for a help that eliminates the requirement of PL2303 and use directly AVR to program ESP.


texts: Understanding D flip flop function - what this thing does

texts:
I am trying to understand what a D flip flop does int he context of building a truth table, so I can design a synchronous divide-by-five circuit. That is, count to five and reset.

I know I need 3 bits to do this. So Q0, Q1, and Q2 will be my bits.

Now, when I build a truth table, it looks like this:

$$
\begin{array}{lll|lll}
\text{Q0} & \text{Q1} & \text{Q2} & \text{D0} & \text{D1} & \text{D2} \\
\hline
0 & 0 & 1 & 0 & 0 & 0 \\
0 & 1 & 0 & ? & ? & ? \\
0 & 1 & 1 & ? & ? & ? \\
1 & 0 & 0 & ? & ? & ? \\
1 & 0 & 1 & ? & ? & ? \\
1 & 1 & 0 & ? & ? & ? \\
1 & 1 & 1 & ? & ? & ? \\
\end{array}
$$
et cetera...

That's the thing. I know the states I want on the Q side should just go 0 - 7 in binary, but I can't get my head around what is happening in the flip flop.

That is, do we take the clock input as 0 to start with, so out first D flip flop input is 0 0, and that output (Q and Q') is then 0 0, and after that the clock is 1, so the Q' bit is now 1 and the Q bit (the one that feds back into D) is now 0, and then?????

dos the input 0 1 -- what happens? I tried to follow the reasoning given in the lecture and I am at my wit's end.

I know this might seem beginner level stuff but I have really tried looking up stuff online and it's no help, because everyone seems to use different terminology. So pretend I am the dumbest, dumbest student you ever met.

And yes I am supposed to use D flip flops.


texts: How to implement an ISP connector on my board

texts:
I'm planning to make a small circuit with a ATtiny85V-10PU. As the pins on this chip are very limited, there are just enough for what I'm planning to do, so all pins will be used for in- or output with LEDs and stuff connected.

When including a ISP connector to this pins, my opinion is, that connected things like LEDs etc. would use the ISP data as power source and maybe the connection could not work to programm my chip (low voltage or something like this). Is there any prevention circuit I should include to be on the safe side, or am I fully wrong?

Is there any best practice, nothing circuit specific?


texts: How to send HTTP parameters using POST method and SIM908 GPRS

texts:
I want to send HTTP parameters using POST method through SIM908 GPRS. Here is and example of what I want to send:

POST /path/... HTTP/1.1
User-Agent: SIMCOM_MODULE
Host: website_name
Content-Type: application/josn; charset=utf-8
Content-Length: Length_num
Accept-Language: en-us
Connection: Keep-Alive
Requst_Body

I have visited this answer: Posting to php server using SIM900 GPRS with AT commands for using POST method to send data but this includes just the request body. What about the request parameters (headers)?

Is there any method to send them through HTTP or should I send them using TCP packet and how can I do it?


texts: What does Low level and High level mean on a Solid State Relay

texts:
I wand to control some 220V lights with 12V but don't  want the noise of s normal relay. So I saw these SSR but do not understand what Low level and High level mean.
Is high level normally closed or normally open? And can these be controlled only with 12v? I ask this because they say 12V, but there is a + and a - where i understand you hook up the 12V, what than is has that CH1 input where they say you have to connect 5V to. So I need 12V to operate it and 5V to trigger it?

https://www.aliexpress.com/item/Free-Shipping-Smart-Electronics-2-Channel-5V-DC-Relay-Module-Solid-State-High-Level-OMRON-SSR/32622381544.html?spm=a2g0s.8937460.0.0.816c2e0eFHD5xA


texts:
ive been trying to create this small circuit but its not working. The truth table should be that of a NAND gate, but instead i get this:

A|B|Q
0 0 1
1 0 1
0 1 0
1 1 0

I've put up the circuit in falstad.com/circuit/circuitjs.html ,tested it , and it came out the same! Why is this happening? I don't understand. Im attaching the text file for the circuit and an image below.

CircuitJS file: http://pastebin.com/Cy7xWG1t


texts: Altium PDF exporter throws all nets off-center

texts: I have a schematic I am exporting to PDF to send.  However, when I use the SmartPDF or export through an outjob Altium moves all net names, port names, and pin names to the left.  Am I missing some setting that is doing this, or is there something about my schematic that would cause this?  I cannot find anyone else who has had this problem in searching.  I have attached an example of what is happening.


texts: Can I hook up a single phase switch to an electric wood splitter?

texts:
Good day. I have a 5 ton Yardmax electric wood splitter that I would like to add a single pole foot pedal switch. Right know there is a Kedu HY56 switch built in. The motor has 4 wires (2 blue, 2 red). The blue wires are hooked up to a capacitor. The red wires go to one side of the switch (there is straight continuity between these). The line wire goes through a reset switch before the push button switch. The common goes straight to the switch.
Can I wire a single pole switch to this, and, if so, how?


texts:
I bought a powerful tweeter (or so I thought) to experiment with the ultrasound.  The device is quite heavy, and it is rated at "350 watts RMS/700 watts peak": 2'' Titanium Super Tweeter PDBT78
Its nominal impedance is "4-8 ohms" with a frequency response of "2-25 kHz".
To make the long story short, the thing burned on me with a sine 20-kHz signal at average (real) power of 9.6 W.  How is that possible?!  The specs promise 350 W "RMS" (I think they mean average power), yet it burns at under 10 W?!  Please review my setup below. Maybe I calculated the power incorrectly and came to a wrong conclusion.  This is how I measured the voltage and current:

The scope displayed waveforms for the voltage and the current and showed their numerical RMS values on the screen.
When the speaker burned, the scope showed \$V_{RMS}=40\:\textrm{V}\$ and \$I_{RMS}=0.24\:\textrm{A}\$.
Thus, I concluded the power was less than 9.6 W. — I don't know how much exactly, because I did not get to measure the phase shift (:
$$P=V_{RMS}I_{RMS}\cos{\phi}$$
Thank you for your interest in solving this puzzle.
PS: I have received a response from the manufacturer:

We test tweeter power using signal EIA-426-B, frequency range
3.5k-20kHZ, PDBT78 power can be 40W ... it has no problem for testing over 8 hours...  The 350W RMS is data on giftbox, it is not true data.

This confirms the community answers.


texts:
Are most batteries built into smartphones (e.g. iPhone) single cell batteries?

If so, why might that be?


texts:
This photo:

is taken from the book:
The Intel Microprocessor Family: Hardware and Software Principles and Applications,
page 298.

This is a 8284 (clock generator) for the 8088 microprocessor.
What is the function of the capacitor and the diode here?
The circuit seems to work without them.


texts: LC circuit with 2 capacitors, one charged, one uncharged

texts:
I have started to learn about LC circuits, in particular in the case where the initial conditions are where the capacitor has previously been charged.

I am struggling to understand what would happen in a case where there is two capacitors and an inductor all connected in parallel, where one of the capacitors has been previously charged, and the other capacitor is uncharged. The capacitors are of equal capacitance.

I have read that you just treat the capacitors as an equivalent capacitor in parallel (2C capacitance) for determining the frequency of the circuit. But what about at the initial conditions? If just one is charged then Q=CV. But in parallel, then Q=2CV, which adds extra charge to the system.

Can anybody explain this to me or provide a link to a solution?


texts: Do op amps need one bypass capacitor or two?

texts:
As with other ICs, it's standard practice to place bypass capacitors near the supply voltage pins of op amps. But I've seen conflicting opinions on how to properly bypass an op amp (here, for example). Some people suggest putting a single capacitor between the V+ and V- pins. Others suggest using two capacitors, one from V+ to ground and one from V- to ground. Which of these methods gives the best result? I'm using OPA827s as unity-gain voltage followers for audio signals, but I'd like to know whether the answer's the same for other situations as well.

simulate this circuit – Schematic created using CircuitLab


texts: Relation between delta cycle and event scheduling in verilog simulation?

texts:
I understand that in Verilog/SystemVerilog standards there are different regions for event scheduling, thus mimicking the behavior of concurrent hardware. But how does this relate to the delta cycles I see in simulators(like expanding at a specific time point to see signals updating at different cycles)?

I can only find delta cycle concepts defined in VHDL simulations, not Verilog. Can anyone explain these two concepts?


texts: can I build a multiplexer with just four transistors?

texts:
Some time back I found a circuit on the Internet that professed to build a logical OR gate with two transistors; accompanying it was a circuit that professed to build a logical AND gate, also with just two transistors.

But then I got to thinking that one transistor by itself is practically a logical AND gate, isn't it? If the voltage at an NPN transistor's base is high, then there will be no resistance between the collector and the emitter, so the voltage at the emitter will be high if the collector is high, and low if the collector is low. And if the voltage at the base is low, the voltage at the emitter will be low regardless of the voltage at the collector.

Similarly, if the voltage at a PNP transistor's base is low, then the voltage at the emitter will be roughly the voltage at the collector, while if the voltage at the base is high, then the voltage at the emitter will be low regardless of the voltage at the collector.

That being the case, could I build a multiplexer with just four transistors via the following circuit? The inputs are bits Co (for control), Il, and Ih, and the output is bit Ou. The semantics are that Ou will take the value of Il if Co is low, and the value of Ih if Co is high. Vcc is high voltage and Gnd is ground.

simulate this circuit – Schematic created using CircuitLab


texts: Adding Low Pass Filter to Open Collector Hall Sensor

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I'm using a gear tooth sensor to create pulses when a metal object passes the sensor. There's a lot of noise on the signal so I decided a simple low pass filter would suffice(f-cutoff = appx.400hz).

The sensor is an open collector type, so the mcu pin is using the internal pull-up to keep it at 3.3v. And falling edges are triggering my mcu timer.

The sensor is connected to the resistor and the other side of the resistor is connected to the mcu pin and the cap. The cap then goes to ground. Like this:

simulate this circuit – Schematic created using CircuitLab

Here is a screenshot from my scope while it's making false counts:

Updated circuit at bottom:
When the LP filter is connected to the input of the Shmitt Trigger Opto-islator(H11L1M) The output does not seem to work. Without the LP filter, it output side works. I've tested these with LEDs. When the hall sensor is triggered, both LEDs should go off. The output LED never comes on to begin with. Is the LP filter affecting the current through the IC?


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I've been browsing around looking for some information on motors\servos and AVR's (my MCU of choice). Motors\servos are in my gray area, meaning I'm still not too into them, but I could do something with them if a job arose.

What I want to do is design a little "plate", if you will, that I can use for one of two things:

I have a bandsaw and could really use a device that will feed and saw things for me. So an X\Y axis device that I can either control position manually, or automatically with a preset that includes size information on what I'm sawing.
I also have a Dremel Press I use for my PCB's. Although I have a great eye and hit my mark perfectly 80-90%+ of the time, automating it would be fantastic. So I would put my PCB on the "plate", and the AVR would position the board at pre-programmed coordinates from like Eagle. And then another motor\servo\solenoid\something would pull the lever and drill the hole; so on and so forth.

The software aspect is no problem for me. So in the purest, most basic form, basically I just need to know the easiest\smartest\best way to use two motors to position an object on an X\Y plane using an AVR (I saw a bit about PWM, but it doesn't seem exact enough to me; maybe I'm missing something). What's the best way to determine distance per revolution with both DC and servo motors?

Thank you all, once again


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I am trying to learn some transistor amplification by simulating. However there is something I don't understand why.

Why all waveforms are somehow distorted or bad-looking sinusoidal-ish waves instead of nice sine waves? Only the Vbase waveform looks decent.


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How SDIO slave device can inform master that it's busy? As far as i remember in some MMC standard there was a information that it can assert SDIO_DATA0 low. Is this assertion possible in every time in communication or only in specific moments?

I'm asking this because i have captured transmission in which I see a big data transfer and at the end of this transfer is a 19.37us of low state on SDIO_DATA and next the transmission continues. Is it normal or it could be a cause of problem?

P.S. I have probes only on DAT2, DAT0, CLK, CMD. DAT3 is not connected.
P.S.2. Device connected as a slave is a wifi chip, not SD card.


texts: Identity and advice on replacement of SM diode

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I have a Sonos Play:3, which is past its warranty. I dismantled it to find it has the well documented fault with a blown capacitor. However, there is also damage also to one of the surface mount diodes. I have sourced some new capacitors to replace those, however I am not sure what spec this diode is, and wondered whether any of you have had the same issue and if any solution was found? It appears to be D307, and has a code of AN 97 printed on it. As far as I can see, I will have to bridge the track to wherever the diode's anode was connected.

Any advice would be greatly appreciated, as I cannot find a schematic or circuit diagram anywhere, and the board is quite badly charred!!


texts: How can I avoid saturation in current source amplifier?

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I'm designing a class d amplifier with current feedback as in figure below

with the following features:

Vbus=50V
Iout programmable from 100mA to 1A rms
Vout=35Vrms max

When the load overcomes the programmed current (i.e. 1Arms) the amplifier saturates and the sinusoidal output becomes a square wave output. For example i want to transmit on 1200 ohm a 35Vrms sinusoidal voltage even though the current feedback is not locked.

So my purpose is to mantain a maximum allowable voltage on the output.

Is it possible to obtain that feature? A second feedback is needed?


texts: Could the metal shield on radio modules be tampered with?

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I see that most radio modules have a metal shield. Is it for keeping the radio waves inside? If so, could a shield be too thick for its purpose? For instance, if one solders another piece of metal plate on it, would it cause any issue? Perhaps, void the FCC certification?

Thanks