texts: Using an SPST knife switch to power on/off a PC

texts:
The title is it in a nutshell

I've got an antique knife switch that I'd like to use to power up (and down) an embedded PC.

The PC power switch is essentially two wires, a ground and +5v (measured with a voltmeter). Normally, a momentary pushbutton is used. You press it for a short time and the PC powers up. Press and hold while the PC is on and it powers down.

I'd like to use a knife switch, so the action would be

1) knife switch disengaged, pc is off
2) engage knife switch, PC powers up, which required a +momentary+ contact, but the knife switch is a constant contact.
3) PC is on while knife switch is engaged.
4) disengage knife switch, PC powers down, which requires another momentary contact, but a little longer duration.

I've found a simple circuit with a 5v reed relay and a 470uf capacitor that could work.

But....

I was really hoping to only connect the circuit to the PC's power switch wires, and not require a separate power supply line.

Is something like that even possible?

EDIT
I don't believe I can add images to the comments so I'm adding the circuit I mention below here. I was mistaken about the 2 capacitors though. It's two relays to control 2 separate buttons, one for the engagement of the toggle, and one for the disengagement.

see this post

http://www.simprojects.nl/toggle_to_momentary.htm

I originally thought I could use something like this, till I realized I'd have to run a completely separate power (and possibly ground) line for it.

I +could+ run the additional lines. I'm really just wondering if the circuit I'm describing is even possible. It seems like it should be, but my EE background is pretty limited.

EDIT: Switch is SPST.


texts: Op-amp for audio-arduino interfacing circuit

texts: Is it possible to use opamp of LM392 in this circuit for interfacing audio to Arduino? I had LM392 laying around so I tried it, but it doesn't work, the output is always exactly 2.50V. I am not sure if the opamp difference is the problem.


texts: Clock domain crossing between OV7670 interface and AXI4-Stream

texts:
Update 1:
My first approach is to use the xpm_cdc_handshake macro in the following way:
xpm_cdc_handshake_inst : xpm_cdc_handshake
   generic map (
      DEST_EXT_HSK => 0,            -- DECIMAL; 0=internal handshake, 1=external handshake
      DEST_SYNC_FF => 4,            -- DECIMAL; range: 2-10
      INIT_SYNC_FF => 0,            -- DECIMAL; 0=disable simulation init values, 1=enable simulation init values
      SIM_ASSERT_CHK => 0,          -- DECIMAL; 0=disable simulation messages, 1=enable simulation messages
      SRC_SYNC_FF => 4,             -- DECIMAL; range: 2-10
      WIDTH => 32                   -- DECIMAL; range: 1-1024
   )
   port map (
      dest_clk => M_AXIS_ACLK,      -- 1-bit input: Destination clock.
      dest_req => AXIS_DestReq,     -- 1-bit output: Assertion of this signal indicates that new dest_out data has been
                                    -- received and is ready to be used or captured by the destination logic. When
                                    -- DEST_EXT_HSK = 1, this signal will deassert once the source handshake
                                    -- acknowledges that the destination clock domain has received the transferred
                                    -- data. When DEST_EXT_HSK = 0, this signal asserts for one clock period when
                                    -- dest_out bus is valid. This output is registered.
      dest_ack => AXIS_DestAck,     -- 1-bit input: optional; required when DEST_EXT_HSK = 1
      dest_out => AXIS_SyncData,    -- WIDTH-bit output: Input bus (src_in) synchronized to destination clock domain. This output is registered.
      src_clk => Clock,             -- 1-bit input: Source clock.
      src_rcv => OV7670_SrcRcv,     -- 1-bit output: Acknowledgement from destination logic that src_in has been
                                    -- received. This signal will be deasserted once destination handshake has fully
                                    -- completed, thus completing a full data transfer. This output is registered.
      src_send => OV7670_SrcSend,   -- 1-bit input: Assertion of this signal allows the src_in bus to be synchronized
                                    -- to the destination clock domain. This signal should only be asserted when
                                    -- src_rcv is deasserted, indicating that the previous data transfer is complete.
                                    -- This signal should only be deasserted once src_rcv is asserted, acknowledging
                                    -- that the src_in has been received by the destination logic.
       src_in => OV7670_SyncData    -- WIDTH-bit input: Input bus that will be synchronized to the destination clock domain.
);

The idea is to design some logic which fills the OV7670 receive buffer (OV7670_SyncData) and starts the domain crossing by asserting the OV7670_SrcSend signal.
The AXI4-Stream transmission logic waits for the signal AXIS_DestAck and when this signal is asserted the data are synchronized and then transmitted over the AXI4-Stream interface.

I am trying to implement an OV7670 camera interface with an AXI4-Stream interface for the data transmission. My current idea is to implement some sort of FIFO or ring buffer to store the data from the camera (i. e. one line) and when the FIFO is full a transmission of the data over the AXI4-Stream interface is started.
But I'm not sure if this is the ideal approach, because I will cross two clock domains (the clock for the camera module and the AXI clock) or is there a better approach?


texts:
I've assembled a circuit which uses RC timing compared to the voltage across a potentiometer. It is intended to run the motor in this fashion:
ON -----------------------       -----------------------
                          |     |
OFF                        -----

by triggering the comparators like this:
    ON ------------------
CMP1                     |
    OFF                   -----------------------------

    ON                           ----------------------
CMP2                            |
    OFF-------------------------

However, the circuit operates exactly opposite this behavior. It is on when I intend for it to be off, and off when it needs to be on. I think that one comparator may be dragging the output of the other to ground, but adding diodes doesn't seem to fix this.

The comparators in this diagram are on the LM393 chip. I'm very limited in the variety of components that I can choose from, and something that relies mostly on diodes and/or resistors works perfectly.


texts: Help with ID of this chip from a Bluetooth speaker - top marking AWF ANG (AWFANG)

texts:
I am trying to find out what this chip is or what it does.

It is from a Bluetooth speaker which is not charging the battery.  I have no idea if this is at fault, but would like to rule it out.

It only has pins on 3 sides, top and bottom has 5 each and left hand side has 6.


texts: Can the output of two 15-amp motor drivers be hooked up in series to achieve a 30-amp tolerance?

texts:
I had a cheap 15-amp motor driver that I bought on eBay. You can see product details here.

I was planning to use this motor driver to power my robot, which uses two 24v wheelchair motors. Then I connected both motors on the motor driver and wrote a simple program that gradually accelerated the motors from 0% to full power. I hooked up two 12v car batteries in series (making 24v) and then connecting this voltage to the controller.

As soon as I ran the program, the motors worked for a few seconds and then smoke came out the motor driver. After I inspected the motor driver, I that saw a couple of MOSFETs were fried along with part of the circuit board. Assume my batteries and motors were correctly connected to the motor driver. Under this case, I would conclude that my motor driver got was damaged due to over-current. The voltage clearly did not exceed the maximum rating. Although I don't exactly know the current rating of the motors, I heard a few experts say that my motors use around 15-amps to 30-amps depending on the load applied.

I do not want to make my own motor driver and I do not want to buy anything too expensive.

Again, this brings me to this question: Can I hook up the output of two 15-amp motor drivers in series to achieve a 30-amp tolerance?


texts:
So I just started learning AVR and I am currently working with the ATMega328P. I have a question regarding the CPU clock. Currently I am using the 8MHz internal clock. Now I know that F_CPU tells the compiler what my clock speed is. The problem here is that the CLKDIV8 fuse is programmed by default, so I was wondering what value would I enter for F_CPU? Will it be 8000000 or 1000000.

I would be glad if someone could clear this confusion.


texts: Thevenin Equivalent Circuit of Ideal Independent Current Source

texts:
This is dual to <Norton Equivalent Circuit of Ideal Independent Voltage Source>. I have wrote it to answer a problem <click here> but I need to make it independent which requires corrections, verifications, comments, etc. In order to follow Norton to Thevenin convertion procedure the ideal independent current source to be converted is represented as a Norton circuit.

Norton open-circuit voltage: For A and B being disconnected, no current flows in the circuit. The internal impedance of the current source is infinite (open circuit) so the open-circuit voltage, \$^{NO}V_{OC}\$, the voltage of A with respect to B is undetermined.\begin{align*}^{NO}V_{OC}&=I_RR\cr&=0\times\infty\cr&=\textrm{NaN}\;\textrm{(undetermined)}\end{align*}

Norton short-circuit current: For A and B being short-circuited, the short-circuit current, \$^{NO}I_{SC}\$, the current from A to B, is equal to the current of the independent current source,\begin{equation*}^{NO}I_{SC}=I\end{equation*}

Then we can construct its equivalent Thevenin circuit. The voltage of the ideal independent voltage source of a Thevenin circuit is the open circuit voltage of its Norton counterpart,\begin{align*}V&=^{NO}V_{OC}\cr&=\textrm{NaN}\;\textrm{(undetermined)}\end{align*}
Its impedance is the impedance of its Norton counterpart, \$R=\infty\$.

Thevenin open-circuit voltage: For A and B being open-circuited, there is no source which determines the open-circuit voltage, \$^{TH}V_{OC}\$, the voltage of A with respect to B. So it is undetermined.\begin{align*}^{TH}V_{OC}&=\textrm{NaN}\;\textrm{(undetermined)}\end{align*}

Thevenin short-circuit current: For A and B being short-circuited, there is no source to determine the short-circuit current, \$^{TH}I_{SC}\$, the current from A to B, so it is zero or undetermined,\begin{equation*}^{TH}I_{SC}=0\;\textrm{or}\;^{TH}I_{SC}=\textrm{NaN}\end{equation*}

The Norton short-circuit current (representing an ideal independent current source), \$^{TH}I_{SC}=I\$, is different from the short-circuit of its Thevenin equivalent, \$^{TH}I_{SC}=0\$ or \$^{TH}I_{SC}=\textrm{NaN}\$. It implies that an ideal independent current source has no equivalent Thevenin circuit. So I can not convert an ideal independent current source to a Thevenin circuit. I need corrections, verifications, comments, etc.


texts: Creating Custom Component + Pattern - Diptrace

texts:
Right now I am creating the schematic and the final pcb layout of my circuit in Diptrace so that I can etch the PCB myself.

I am going to use LM2985-3.3 SMT LDO from Texas Instruments in my circuit to step down the 5V supply. This IC is available on SOT23-5 package. Since I could not find this component in the default libraries, I am attempting to create my own.

Couple of questions

In SOT23-5, what does 23 and 5 stand for?
The chip dimensions in the datasheet are not exact, but a pair of min/max. Why is this so ? While drawing the component, which one do i take into account?

Lastly, any good link to a good tutorial for creating custom component/pattern in Diptrace?


texts:
I've been reading Fundamentals of Digital Logic by Vranesic, and while it goes over the syntax of Verilog, it doesn't really say how to use any of the tools available for Verilog.

It seems there isn't any IDE for writing Verilog.  I'm used to programming in languages such as C, C++, Java, etc. and all of these allow me to compile them with an IDE/terminal and I see an output for what I've written.
I don't understand what the output of Verilog is supposed to be.

For example, lets say I wanted to write a module for an AND gate:

module andGate(x, y, z);
  input x, y;
  output z;

  assign z = x & y;

endmodule

How would I know this is correct?  Is there some console I can interact with, where I can apply hi/lo to the inputs and see that it actually works like an AND gate?

If there's any programs you can recommend for Linux, I'd really appreciate it.  Also, I'm just a hobbyist, so I have no real reason to buy some commercial license/software.


texts: Opamp Supply Current vs Output Transition Frequency

texts:
I am dealing with an NC2200 op amp that should consume no more than 10uA.
But the datasheet shows the following graph, which I haven't found something exactly like that to understand what does mean exactly:

Simply put, does that mean that supply current increases with the output frequency? So if I amplify a signal of 10kHz at 5V supply, I consume 20uA instead of 10?


texts: Does parasitic capacitance increase the load value of electrodes?

texts: I'm reading Samsung Display's patent about a display notch. In this patent, the inventors say that providing a parasitic capacitance to scan lines increases their load values. Can anyone tell me why?


texts: Question about local NFB in a transistor

texts:
I've seen this a few times and I can't seem to find documentation so maybe I'm not understanding what's happening here. My interpretation is that the transistor is configured as a common emitter and the circled capacitor is acting as a high pass filter, passing the inverted signal back to the base, thus attenuating the higher frequencies.
Is this a correct understanding, and if so, how exactly do I calculate the effect?
And also, if you could point out further reading on the topic, I'd appreciate it.


texts:
I'm really new to Electrical circuits so please bear with me.
 I studied how set latch works :firstly, input 0 then Q(let's say output and it's 0 i  this case) feedback another input resulting output 0. Then if I input 1, the output Q turns into 1, as a result it latches 1.

Here's my question. How do you know that output Q is 0 in the first place even though there is only one input gets 0 (the other input is affected by the output)?


texts: Can I include heatsink copper in a Kicad footprint?

texts:
I have some SMD parts that have a recommended copper pattern for heat spreading. Can I include this in a Kicad module? I don't see a convenient way to draw filled copper polygons that aren't pads. I'm concerned that a heatsink constructed from pads will exclude desirable soldermask.

The specific part is just a CLV1A Cree RGB LED in a PLCC4 package. http://www.cree.com/products/pdf/LED_Lamp_SolderingHandling.pdf


texts: I can’t remember the name of that component

texts:
I’m looking for the name of the component that act like a relay but instead of using a coil to generate a magnetic field that moves the relay « arm » it uses a LED and a photosensor.
It allows to isolate a high voltage of a circuit from a low voltage.
Thanks a lot!


texts: What is the logic behind using the “zero volt-seconds” assumption for the analysis of converters and What are the limitations of analysis based on this assumption?


texts: Is it safe to have a ground plane under a Bluetooth module for a DC-DC converter?

texts: I am finishing up routing a 4 layer DC-DC converter PCB. My concern right now is whether or not it is safe to have a ground plane directly under a Bluetooth module on my PCB. Since this is a switching converter, my concern is that the ground plane may become noisy, and will interfere with the antenna (or possible the entire Bluetooth module) and will prevent the module from receiving proper signals. I am not very experienced  in RF, so my knowledge is pretty limited, but I just wanted to get a second opinion. The Bluetooth module I'm using is the HM-11, and the frequency of my buck-boost converter is set to 750 kHz, in case that info is needed.


texts: Why do these diode connected JFETs not clamp my output?

texts:
I've attached the LTspice image for some clarification, perhaps someone can see where I've gone wrong. I need to use JFETs to reduce the leakage currents (the outputs are going to an 18 bit ADC). Why are they not clamping the outputs to ~-0.2 - ~5.2V?
I've added some series resistance to the supply of the single ended to differential converter, which helped slightly, but as you can see, it's still not clipping.
Any ideas?


texts:
This video shows that current only travels in circuits or "circles". This is in a way intuitive because a battery needs the electrons to return otherwise the reactions inside won't continue (I guess).

But it is also counter-intuitive because if you think about it, an electron is always attracted to a positive ion(that's why currents of electrons occur in the first place). So the electrons on the negative side of the battery should be attracted to something positive even if there's no loop( or at least some electrons on the surface should move,  right?).  An example would be the lighting on the sky. All the electrons are stored in the atmosphere and dischared into the ground without an obvious circuit. Another example is the ground system in all houses (an appliance can discharge into the ground).

How can there be two ways in which electrons move?


texts: My breaker panel shows the island and wall receptacles (two separate breakers) in my kitchen have 20A breakers. I noticed the outlets do not have the "T" shaped plug, making me think they are possibly 15A outlets. Is there a way to reliably determine if they are 20A rated? I'm guessing I should probably just pull the cover and try to determine what gauge the wire is.


texts:
I am designing a circuit for a GPS receiver IC and RTC.
As both of them require a V_BCKP connection I will be using a CR2032 (non-rechargeable) battery for V_BAT supply.
To make sure the minimum use of battery I want to mainly use VCC (3.3V) from my MCU whenever it is powered on and use the battery only when the MCU is off.

Although this is the same circuit as recommended in the Datasheet for a "rechargeable battery", I don't understand why this won't work for a non-rechargeable battery. Please help me understand.
My proposal to the circuit is using 2 diodes and 3.3 VCC will be automatically selected because it has higher potential than the battery I am using.


texts: Which capacitor for a high current resonant system?

texts:
I would like to build a induction heater.

simulate this circuit – Schematic created using CircuitLab

V1 will be a ZVS system that is out of scope of the question.
Accordint to my computations and confirmed with simulations, the current into C1 will be a sine of 56A RMS at a frequency of 100kHz. 70V pk-pk.

I may consider replacing C1 by several capacitor to reduce the current rating of each of them. I may also consider adding a radiator if needed.

In summary the requirements are (at 100kHz):

56A rms
70V pk-pk
Not polarized
2.2uF or less if several in //.

What capacitor technologies are suited to this application?


texts:
I recently set up a qrp pixie 2  transceiver i purchased from Aliexpress.I want to use it for sending morse code,and  listening to the shortwave transmissions.and i want to learn more about it.so i need to set up and antenna for it, i need  help with what kind of antenna i should use, and how can i make it.
This is the qrp pixie kit I'm talking about:

https://m.aliexpress.com/s/item/32671273995.html?spm=a2g0n.search-cache.0.0.7dc3a52561enmM#autostay


texts:
I need to monitor the charge condition of an 8V lead acid battery.

For monitoring purposes, I used a Beagle Bone Black (BBB) running Linux. It is also supplied via this battery. The battery also supplies three DC motors (switching on and off) and a camera.

Now if the charge falls below a certain percentage, the BBB should report this via SSH and shutdown.

Now my problem is:

How can I determine the state of charge? Is it sufficient to measure voltage every ~50ms and report "Low power" when the voltage is below a certain value for 1s, or do I have to use a fuel gauge IC like this one? If so, which one is easy-to-use or has a tutorial or reference project I can stick to?


texts: Reading a negative and positive voltage through Arduino

texts:
Currently struggling with a problem due to my limited electrical engineering experience (1 first year course).
I'm working on a project for central locking in the toolbox on my ute. The actuators within the car are sent a voltage that alternates between 12V and +12V for 'unlock' and 'lock'. I am trying to somehow convert this voltage into something that can be read by an Arduino as an input to ultimately activate the servos on the lock.
From what I have been able to find maybe a voltage divider circuit or an op-amp. The photo below is how the car's locking system works.


texts: Long Term effects of saturating isolation txfr

texts:
I have a 1:1 isolation transformer that's rated for 25VA. I'm consuming 30VA, 20W.

I've noticed because I'm saturating it, the txfr is no longer 1:1, it's more like 1:1.1.

Other than this issue, for my application is working fine.

Is there anything else I should be worried about? Will saturating the transformer this way "wear" or damage the txfr out over time?

Edit:

Bottom meter is primary (main supply)

Top meter is secondary (powering my load)


texts: FQPF5N60C MOSFET turns on but limited current

texts:
I am a software engineer by trade and an electronic hobbyist, so please be gentle :)
I am using a FQPF5N60C N-Channel MOSFET to switch on a 12v motor using a Raspberry Pi.
The spec shows VGSth at 2 - 4v and I am feeding 4.47v into the gate and the MOSFET indeed turns on, but .. it seems to be quite restricted by current resulting with the motor turning very softly (compared to when the motor is connected directly).
Any idea what I am doing wrong?
Thanks!
EDIT: added schematic


texts: "Standard orientation" for stepper motors in data sheets

texts:
I just finished getting a SOYO 6V@0.8A unipolar stepper motor working, and wanted to know more about an issue I faced while doing so.

I used the stepping sequence below with an L293D chip to drive the current for the stepper motor:

So, I pulled up the datasheet for the motor, and took a look at the wiring diagram:

Based on this layout, I assumed the polarities (assuming M1+==1a, M1-==1b, M2+==2a, and M2-==2b):

M1+: Blk
M1-: Grn
M2+: Red
M2-: Blu

So, I wired the motor like so with respect to my current driver:

However, this did not work as expected, and when I used my gray code logic, the motor just ticked back and forth. So, I ended up changing the wiring to the following, and it worked:

M1+: Grn
M1-: Blk
M2+: Blu
M2-: Red

And it worked. So, my question is: is there a "standard" representation of stepper motor diagrams in data sheets I could use so I get this right the first time the next time I use a different motor?

Thank you!


texts:
Consider following system:

To keep the mixer's LO and RF phases in quadrature I'm using a voltage controlled phase shifter. I know its phase change per volt constant in rad/V at my center frequency.

Now I need to design a feedback circuit to automatically adjust this phase shifter input but I'm unable to model the phase shifter in phase domain.
This looks like a PLL but phase shifter is not a VCO so integrator VCO model is not correct.

How can I model the phase shifter in linearized phase domain?
Or is this the right way to design this circuit? any help is appreciated.


texts: Given the two 16-bit buses, D_0 and D_1, shown in the figure below, what is the bus width of the 2-input bus Y?


texts:
In the field of Digital signal processing I have seen people using words

Complex signals and Negative frequencies. For eg. in FFT Spectrum.

Does it really have significant meaning in the time domain or is just a part of the mathematical symmetry.

How do you visualize negative Frequency in Time domain ?


texts:
I am trying to analyze all components in one home-made GPS receiver and I am stuck with figuring out how to determine Noise Figure at the mixer output.

See picture below:

If we are going from the input - ground noise level is at -174dBm and LNA amplifies it with 28dB of gain and adding 0.8dB more, so by now we have: -174+0,8+28.OK, going further - since SAW, COAX and MIXER are attenuating signals they are also attenuating the noise therefore their sign is negative(-174+0,8+28-1,5-3,9-6). What is confusing me is why after RF amplifier MGA-86563 we are not adding +20(GAIN)+2(NF)?

Instead we have: -174+0,8+28-1,5-3,9+20-6+10*log(BANDWITH)=-73dBm.

Why is this wrong: -174+0,8+28-1,5-3,9+20+2-6+10*log(BANDWITH)

What is wrong in my analysis? Did I misunderstood what NF is?

EDIT: I forgot to write +28 in the last expression.


texts: Circuit abbreviation: GND, MIN, TRANS, etc?

texts:
I am originally a programmer, so I am not quite experienced in circuit symbol and abbreviation. I receive a custom made 2-in-1 Light photo diode receiver + Current-to-Voltage converter from my professor and I'll have to write microcontroller program to receive data from light. However, there's 6 pins, and I don't know what to plug into those 6 pins. There are some notes written: 4.5V, GND, OUT, MIN, DIFF, TRANS. I only know that I should plug in 4.5V supply, Ground, and Output. I have absolutely no idea about the other three abbreviation (MIN, DIFF, TRANS). Unfortunately, my professor isn't available during this week, so I am on my own. Can you help identify what are those pins for?

Diagram: https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-prn1/t1/q77/s720x720/1925344_10152043333083095_442508481_n.jpg

Actual Circuit: https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-ash3/t1/p296x100/1977361_10152043333208095_1265265624_n.jpg


texts: Do high power through hole resistors need a heat sink

texts:
I'm using the following resistor: click. To be precise, the MCKNP05SJ050KAA9 found here. From what I've been able to determine, my device is the MCKNP 500-S, measuring in with a length of 17.5 mm and diameter of 6.5 mm.

Now, I'm wondering whether it is first of all possible, and second of all needed to put a heat sink on though-hole power resistors.

At first I had found SMD Power resistors, though the only ones that could dissipate the required 4.5 W was a 35W. This one did have a metal plate on top for a heat sink. But for Through-hole components, I haven't got a clue.


texts: MOSFET Safe Operating Area vs Maximum Ratings

texts:
I've been building a project using some Infineon IPA093N06N3 MOSFETs. I carefully picked the correct values for the MOSFET that I needed, and calculated an estimated Tj based on the thermal resistance of the package I was using.

I only just noticed today the Safe Operating Area graph in the datasheet whilst looking up the pinout for the package. The SOA suggests that this MOSFET (and a lot of others I took a look at afterward) is only rated to "safely operate" in a very small window, despite the much larger maximum operating conditions listed on the first few pages of the datasheet.

Taking the linked datasheet above as an example, it states that the MOSFET is capable of a VDS of 60V and a ID of 43A. A further look on page 4 shows the SOA graph, which states that at any VDS over 10V you are limited to a ID of 10A. I previously assumed that, so long as you stayed inside the maximum ratings and you could cool the MOSFET to below Tj(max), that any value for both of these would be alright.

If the MOSFET is capable of switching a large current whilst staying under the Tj(max), what other limiting factors might there be that would cause the manufacturer to state that they are only capable of smaller currents above certain voltages?


texts: Isolating techniques for single power supply

texts: Hello. I am working on a product which is used for measuring current from multiple channels(16 nos per device) using an onboard ADC. The device is powered by a 24VDC supply. Now even though the devices will not be connected together at the consumer end, at my testing and calibration station it will be great if I could power multiple devices(say 10 nos) using a single supply as my operating current isn't too high. As shown in the figure, I would want to use the lower configuration which has only one supply. The problem I'm facing is that because of the common supply(and specifically because of the common Ground terminal from what I can understand), the readings of my ADC are unstable and shifted. One solution I found was to use an isolated power supply. But I wanted to know if there is some other way to isolate without changing my present power supply. What I can do easily is make a small power distribution/isolation board if I can find some cheap solution to the problem. If I am wrong about the problem being isolation please help as well. Thank you.


texts: If I am using a channel only for morse code (CW), with one frequency and interruptions for dots and dashes, is the necessary bandwidth of the channel twice the audio frequency of the tone used for CW?


texts: How can I tell if a cable is rated for use as motor leads with a variable frequency drive?

texts:
I understand that the switching edges generated by a VFD can cause corona breakdown of the insulation on the motor leads. Due to this, it is recommended that some cables be used for VFD motor leads, and that others not be used. How can I tell? I am particularly interested in Lapp ÖLFLEX® CLASSIC 110 CY.

https://products.lappgroup.com/online-catalogue/power-and-control-cables/various-applications/pvc-outer-sheath-and-numbered-cores/oelflex-classic-110-cy.html


texts: Reasons for glitches observed on PCB from physical touch of floating enclosure

texts:
I have a circuit on a PCB on which I’m observing “analogue glitches” when making physical contact with the enclosure.
This enclosure is from ABS and there is a circular connector on one side for supplying USB power on the enclosure connected to the internal circuit board. The ABS enclosure is otherwise “floating," isolated and not generally connected to anything (unless USB power is connected to the circular connector.)
This physical contact does not seem to generate an electrostatic discharge as one might when walking across the room and then grounding to some earthing point. The circular connector shell on the enclosure is metallic and is isolated from the PCB through the ABS material. The internal contacts of the circular connector do lead to the internal PCB through about 5cm of wiring but they are also isolated of course from the circular connector shell. No explicit effort was made to connect the connector shell to the PCB ground etc. so the shell is essentially "floating."
Touching the circular connector shell with a metallic object such as a small metal ruler or screw driver, or simply a USB cable (the metallic part, without insertion) may generate this glitch that is observed on some of the I/O lines (some of which lead to CMOS level inputs, eg  D-F/F etc.) It does not seem to be of an ESD nature, but somehow is observable simply by tapping the connector shell in that the D-F/F clock is sequenced on this clock-line generating an unwanted toggle. It is not always reproducible, and there seems to be a requirement for some delay between subsequent contacts before the glitch becomes evident (almost like a charging phenomenon.) It is quite strange to say the least.
What is the nature of this induced signal “passed on” to the PCB in the enclosure? Inductive, capacitive, radiative, etc.?  How does this signal makes it through and what would be done to filter it out?
There seem to already be 5V TVS diodes on the connector input pins for ESD bypass in case of an ESD event, but in this case even if the tiny ESD is hugely attenuated to the PCB ground when it occurs (even though I’m not sensing this,) there is still the possibility of a residual that may be the cause of the glitches that are in the range of about x2 logic-levels, that is a few volts (positive and / or negative) but < 12V. The oscilloscope measurement level may not be the most accurate given the ground clip inductance etc, but the observed glitch event being correlated to the physical touch definitely is confirmed on visually on the oscilloscope.
Now I have heard some suggestions that series resistances, and or RC low-pass filters on more susceptible signal lines may greatly improve or attenuate this phenomenon, but otherwise is there a more direct way to prevent this on the enclosure itself? I am not seeing how the ABS with GOhms of material resistance can even conduct the smallest of currents, and why the connector shell might make this more probable even though the inside of the connector is also isolated from the shell by at least 100s of MOhms.


texts: Can drain voltage/current affect gate voltage of MOSFET?

texts:
By way of disclaimer, I do not know a whole lot about MOSFETs, so there is a good likelihood for errors in my question.

I am debugging a PCB where a voltage line is too high and I am trying to identify the faulty component. I have replaced the voltage regulator that regulates this 1.8V line twice, but the line still is measuring ~2.4V (on multiple meters) so I don't think the voltage regulator is at fault.

This 1.8V line is used as the gate for multiple MOSFETs throughout the PCB. I have been doing a lot of research and have read some things about the relationship between the drain and gate of MOSFETs. Namely, that the drain-source current increases as the gate voltage increases, and that Vds = Vg - Vt (where Vt is the threshold voltage).

So, are the inverses of these statements true? If the drain-source current was being increased by some other component, would that cause Vg (my faulty 1.8V line) to increase? If Vds is somehow increased, would that cause Vg to increase or Vt to decrease?

Thanks for the help. I will do my best to clarify if need be.


texts: How does the range of bluetooth increases by adding an antenna?

texts:
I have seen too many tutorials on how to increase HC-06 bluetooth module range. They all involve cutting the on-board antenna and adding an external one (a piece of wire or a 2.4GHz antenna). I was wondering how this affects the bleutooth module, for example, the power consumption, the frequency. And the relation between the length of the wire and the transmission range. Can anybody help?

Thanks in advance,


texts: Why does this 7-segment display not light up?

texts:
Why this (IC7447 and 7 -Seg combo) not light up?
  I'm not sure as if what to do of the 3 lines of the IC7447 (Pin - 3,4,5) which I've depicted in GREEN below. Because at certain sites they have been shown ACTIVE LOW, but they are connected to +Vcc while many others even don't have connections for them(as seen on YouTube videos.they just leave them isolated).
  So I'm confused so as what combination of connection to have for them.

IMAGE: With few Discriptions

This is the same IMAGE with adjustment so that wirings will be more clear to see.

This 7-SEGMENT is for my ELECTRONICS PROJECT of ALU(Arithmetic & LOGIC UNIT),
for 4-bit adder.


texts: Something weird happened to my Layout Editor

texts:
I thought I am done with these weird things that seem to happen/change every time I open the same not changed file, but I guess I am wrong. I have been working on this circuit for days and now there are markers (green boxes) on some instances (see in picture)

Ever since they showed up, unlogical silly things have been happening (like I cannot copy the cell or now it would not allow me to connect it to a different net). How do I go back? what is this?


texts: Why did this arduino burn out? SilentStepStick (TMC2130) stepper at 24V

texts:
I'm new to electronics.

Attempting to bench-test a SilentStepStick stepper driver board, (based on a TMC2130)

Using: Arduino Uno, a SilentStepStick driver board, a 0.6A stepper motor, and waterott example code (using SPI).

The motor turned as expected, code and wiring appeared to function, for about 30 seconds, Then "all the smoke leaked out" of the ATmega328P, in the Arduino, and the Stepper Driver burnt out also.

Process & Problem Description:

Turned on 24v power, as per datasheet 24v must be connected before 5v (VIO).
Plugged in arduino USB-B plug, did notice some faint blue sparks, between the grounding parts of the connectors. Didn't realise significance.
Motor turned, code worked.
After about 10 seconds noticed a very faint burning smell, disconnected arduino and checked motor and driver for heat, none found.
Reconnected for 10 seconds, faint burning smell resumed again, disconnected arduino.
Reviewed code, found example code was setting current to 50%
Changed code, lowered current to 6%.
Reconnected, motor turned ok, smell returned, then a few seconds later the ATmega328P visibly fried, stepper driver was fried also.

I have triple checked all wiring prior to posting this, all seems correct.  Perhaps too much current was applied?
If so, I am unsure why that would affect the arduino - isn't it just providing signalling? Or did 24v somehow make it's way to the arduino?

Here is the wiring diagram:

I have power from the arduino 5v rail to Vio, and GND->GND, and the 24v power supply is connected to VM & the second ground.  All SPI and stepper control pins are connected.

Why did it blow up?

UPDATE:
-If I measure voltage between the ground of the USB cable, and the arduino ground, when the cable is not plugged into the arduino - then I see 24 volts (!)
- It is clear that 24v is going through the driver, and into the arduino, over the 5v rails (Vio).

Per helpful advice from comments, issue is likely with grounding: Arduino is powered via USB, from an Intel NUC Desktop, which is powered by DC only - no ground.
The 24v power supply is grounded to earth.

UPDATE - Solved:
-Thanks to the gracious advice from the comments, solution found.
-The Arduino logic power suppy was via USB, from a "Intel NUC" DC-powered desktop - there is no earth.
-The 24v comes from an earthed power supply.
-The two devices do not share a common ground, & the 5v is not earthed. I presume this to mean the 5v power supply is "floating" relative to the 24v power supply, and this is what caused the issue.
-The problem was resolved by obtaining an earthed 5v DC power supply, and connecting the ground of the 5v supply to the ground of the 24v power supply.
-Images provided below to clarify.  Only power wiring shown for clarity

Original Problematic Wiring:

Solution Wiring

I would be very happy to accept a formal answer to this - if someone wishes to state in technical terms, what likely occurred in the first wiring diagram, that would be great and perhaps make this a useful question.
Summary: In the first diagram, one power supply was not earthed, and the two power supplies did not share a common ground.  The result was: a visually burnt TMC2130 driver, a visually burnt ATmega328p in the arduino, and some black burn marks in some sockets on the breadboard.


texts: Difference between PIC16F877 and PIC16F877A?

texts:
Is there any difference between PIC16F877 and PIC16F877A?? I checked the datasheet, but didn't get any answer.

From my experience, we can use 877 instead of 877A and vice verse.

Is there any situation we can't interchange these parts.


texts: Two circuit voltage 5V, 12V efficiency with one supply and convertor

texts:
Currently i'm bulding a circuit that need two voltages.

5V to feed the microprocessor, sensor, leds, LCD and others
12V to temporary feed small water pump (12V 4.8W) and a Electric Solenoid Water Valve (250mAh) [Activated by a MOSFET from MCU]

5V Will always run, but with a timeout that disable lot of sensors, leds, lcd, etc to save power, when user click any button it awakes. From x to x seconds it will auto awake to update sensors and values and sleep again.

12V will only be needed to turn on pump and valve by user interaction (Click a button) to fill a glass of water for example.

I have a 5V 5A brick power supply with stabilization that i run some of my projects. The main question here is if i use this power supply with some or one boost convert 5V->12V will be better than run 12V and buck converter to 5V to main system

Note: 5V Circuit can reach max 2A when its all ON and at Max Brightness


texts: Why is a variable frequency drive (VFD) always powered from a phase shift transformer?

texts: I have seen VFD of rating (350kW and above) are generally powered from a phase shift transformer. Even when the load is considerably high why cant we use an ordinary transformer instead of phase shift transformer


texts: Voltage multipliers work worse with more stages?

texts:
I'm simulating voltage multipliers (Dickson topology) with the stages from 1 to 12, following the paper "Design Optimization and Implementation for RF Energy Harvesting Circuits, 2012". The load was fixed at 15 kOhm.

What made me confuse was that, in my simulation results, the output voltage was lower at low Pin (input RF power) when the stage increased, although it was higher with higher Pin. And the power conversion efficiency (PCE = Pdc/Pin x 100%) was decreased. I attached my simulation results for the comparison.

In the paper I mentioned, they intended to design a system that the output voltage reached 1.8V at Pin = -20 dBm (?). And they got this by parallel connection of 2 circuits, one with 7 stages and one with 10 stages. Their efficiency is higher with more circuits (file attached).

Here is my results

Could anyone get the multiplier results the same as that of the paper? I tried using different matching topologies and values, but the results are still the same trend: decreasing with higher stages!


texts: What does NC mean in this pinout diagram for an ESP8266?

texts:
The ESP8266 Datasheet has a Pin 5 labelled as VDD_RTC and it describes its function as "NC (1.1V)".

I usually understand NC to mean no connection on most ICs, or on relays as normally closed. Neither of those seem to apply here. What does it mean in this case?


texts: How to remove DC power supply noise while load is active?

texts:
I'm using a breadboard power supply to power up two STM32F103, two Hall flow sensors, one IC555, and one 16x2 LCD with backlight. While everything is connected I have alot of noise in the system which is interfering with my measurements. Input to the breadboard module is 12V DC /2A.  Here are the osciloscope images of 5v output and 3.3 V output.

I was thinking of soldering a 1000 microFarad capacitor before the voltage regulator , and adding in parallel to each output a ceramic 100pF capacitor. Will it work?, And how to actually calculate the exact capacitance required to filter this kind of noise? (Sorry for the badly photographed images)

Schematic of the whole system is located below.

5V and 3.3 V is connected to the breadboard power supply mentioned above, while 12V is a seperate module. Hall sensors.


texts: Verilog: Posedge sensitivity vs. If statement in Always block

texts:
I have recently completed a design that had run into timing issues (negative slack).  The modules that were found to be troublesome, from the timing reports generated in Vivado 2017.4, are these modules that are used to calculate some synchronous outputs.  A clock, reset, and enable (en) signal are provided as inputs.  The modules that had these issues were previously implemented as shown below:

always @ (clk, rst) begin
     if (rst) begin
          ...
          ...
     end
     else if (clk & en) begin
          ...
          ...
     end
end

A coworker suggested that the "code is creating latches for the pipeline segments, instead of clocked flip flops".  Following his suggestions I changed the modules to what is shown below.

always @ (posedge clk, posedge rst) begin
     if (rst) begin
          ...
          ...
     end
     else if (en) begin
          ...
          ...
     end
end

This seems to have resolved the negative slack coming from these modules, but I am curious to know why this is the case.


texts: The proper way of using gm/Id plot for designing an amplifier or OTA

texts:
For any design of an amplifier or OTA, we are given the specs which we need to achieve including:

Gain
UGBW or 3db BW
Slew rate
Power consumption
Phase Margin
Load capacitance

I would like to design a folded cascode using the gm/Id method. I was able to successfully get all the gm/Id curves for NMOS and PMOS for my technology node. I did that for a family of channel length (4 values). I got the following plots:

fT vs gm/Id
gm*ro (intrinsic gain) vs gm/Id
Id/W vs gm/Id
gm/Id vs Vov= (Vgs-Vth)

I also got the same plots vs Vov instead of gm/Id.

I am trying to understand, given these plots and given my specs, how to approach the design process. I have input transistors, current mirrors, and cascode transistors in my design.

My question is sort of general, how to design a cct using gm/Id method given the specs and the plots.

I found this flow diagram online but couldn't make sense out of it.


texts:
I’ve been struggling with this circuit for over an hour I’m trying to find the transfer function, can anyone help me with that?
![enter image description here]
Here are my attempts on this:
(https://i.stack.imgur.com/eMy2G.jpg)


texts: How does the PNP transistor in this IR receiver circuit work?

texts:
(source: https://circuitdigest.com/electronic-circuits/remote-controlled-light-switch)

How does the BC557 PNP transistor in this circuit work?

Based on the information about PNP transistors that I got so far, the emitter is usually not connected to ground and the collector is usually connected to ground. So the way the PNP transistor is connected in this circuit confuses me.

I understand that the 1 microfarad capacitor discharges and charges after an IR signal is received (e.g., after a button on a TV remote control is pressed). And the purpose of the mentioned capacitor is for the IC to count the IR pulses as 1 pulse. So after the last pulse, the IC's pin 14 should receive a "HIGH" input. But how does the charging and discharging of the capacitor work with the PNP transistor in this circuit? How does the IC's pin 14 receive a positive voltage?

This circuit may be good or bad, but I am only interested in understanding how the 1 microfarad capacitor and the PNP transistor send "HIGH" input to the pin 14 of the IC.

UPDATE

This question is relevant to:
Purpose of 1 microfarad capacitor in IR receiver circuit

But this one is more about the PNP transistor. The answer on that other post didn't clarify how the PNP transistor in this circuit works so I asked about it separately.


texts:
I am controlling a stepper motor (M42SP-5P) with BUZ11 MOSFETs. The winding resistances are \$22\Omega\$ and each winding is 18 mH as I measured. I am driving it with 24V, so let's say the drive voltage is about 1A. I know that the datasheet doesn't agree with me, however, this motor is M42SP-5P, not x-5K or x-5.

According to the MOSFET datasheet, turn off time is about 150 nS.

I want to pick a kick-back diode, however I am confused with the kick-back voltage calculation. The equation is:

\$v(t)=L*\frac{di(t)}{d(t)}\$

\$v(t)=18*10^{-3}*\frac{1}{150*10^{-9}}\$

That gives us 120 KV. This is insane and cannot be true, right? Where is my mistake in this scenario?

Also, which one of the following should one look for in the datasheet of a kick-back diode for this specific purpose?

\$I_{FSM}\$ : Non-repetitive peak forward current?

\$t_{rr}\$ : Maximum reverse recovery time ?

\$V_{RRM}\$: Maximum repetitive peak reverse voltage ?

Will 1N4148, BA157 be suitable for this application?


texts: Correctly choose circuit decouplers and filters and schematics advice

texts:
I want to ask some help to correctly design a power supply circuitry with TPS799 voltage regulators.

I've this reference circuitry:

And nothing more explainations. I want to use same specifics of filters but using a TPS799. Also i want to add another TPS799 and add decoupling capacitors.

Environment where i'll use this circuit is near a 2.4ghz wifi trasmitter and some low frequencies ~75Khz noise.

Now, first of all i have some questions about TPS799:

I see in datasheet to use 0.1uF to 1uF as input capacitor, which should i use? And what differences i may have?
I see in datasheet to use 2.2uF or larger as output capacitor, which should i use? And what differences i may have?

This is a circuit i've designed after some advice is:

An advices i've recived is not to use FB becouse it's a poor pratice, so i've replaced it with LC filter.
I've used lowest cap size specified in datasheet. Added some random decoupling capacitors and put all togheder.

I want to ask:

Is my circuit designed using usefull value and right component position?
Can you check my decoupling capacitors and positions?
Looking for original schematic image(top of the post), is this an equal design?

Some questions about electronics.

I've placed LC filter in the output:

Is this the same as use LC filter in input?
Should i use the same filter in input and output?(it have a sense to filter two times the same frequency?)
What use have FB? It may be usefull to filter wifi frequencies?
How i can optimize values for have a good BOM(not lower, but same cap sizes for example) and have the same circuit design?
Can i replace C7(electrolityc) cap with a ceramic?
Should i filter with a LC filter the digital power supply?
Is correctly wired I2C connection(i will use 4.7Kohm resistor istead of 1Kohm)?
Should i filter in someway VCC?
What SMD dimensions are good for this application considering that max. current is 200mA.

Thank you for any help.


texts: Confusion about variable capacitors/diodes

texts:
In a lot of circuits (especially with the 555 timer), I see capacitors used to set the duration/frequency of something.

Now mostly the value of a capacitor can be calculated, however, what if I want it to be variable, and controllable from a microcontroller.

I know there exists varcaps/var. diodes etc, but if I look at the data sheets they only mention they are for radio/TV tuning.
For resistors there exist variable resistors ICs, and I would expect something similar for variable capacitor ICs.

Do I miss/oversee something here?

(update) Example:

See link Example circuit

Using for C: 100 nF
Using for R1 and R2: MCP42010 (100 kOhm version, see Datasheet

Slight problem is that the wiper resistance is 125 ohm, resulting in a minimum frequency (using the calculations in the circuit link) when using 100 kohm is 48 Hz, and maximum frequency (when using 125 ohm) is 48 Hz.


texts: Measuring opamp output voltage (with virtual ground) on arduino

texts: I have been working on a simple project to read the analog voltage input on Arduino. I'm having problem to read the correct value on Arduino. I know what's causing the problem. I'm using the virtual ground on the op amp non-inverting side but Arduino is referencing to the digital ground instead of the virtual ground when reading the analog input value on pin A0. How can I solve this issue?


texts:
I'm studying about STM32 low power modes, and after program the device with __Wfi instruction I cant program another firmware in the device, I tried to use the STM utility to erase the code, but it show that the flash had write protection.

The first error that show is :

adapter speed: 24000 kHz

adapter_nsrst_delay: 100

Info : clock speed 24000 kHz

Info : STLINK v2 JTAG v34 API v2 SWIM v7 VID 0x0483 PID 0x3748

Info : using stlink api v2

Info : Target voltage: 3.192646

Error: init mode failed (unable to connect to the target)

in procedure 'program'

in procedure 'init' called at file "embedded:startup.tcl", line 495

in procedure 'ocd_bouncer'

** OpenOCD init failed **

shutdown command invoked

After a search, I found that I can get the firmware putting the boot0 in VCC, so I did this, and the follow error was shown:

** Programming Started **

auto erase enabled

Info : device id = 0x10076413

Info : flash size = 512kbytes

Error: stm32x device protected

Error: failed erasing sectors 0 to 0

embedded:startup.tcl:476: Error: ** Programming Failed **

My board has a stm32f407vet6 processor. I'm using a ST-LinkV2 clone, for download and debug purposes.


texts:
I have a cheapo Weller 40W unregulated soldering iron. $20 at the local everything store. I've gone through quite a few soldering irons/tips in my life, this is just the latest one. I'm fairly certain I know why my tips get chowdered after just a little while of use: it gets too hot. There's nothing I can really do about that, seeing as it's unregulated...or is there?

I'm wondering, is there anything I can make that will at least give me some control over the temperature of the tip? I'm using regular .032 diameter, 60% tin/40% lead solder. It seems obvious, but would simple voltage regulation (perhaps from a variac) work to lower the total power? It seems fairly obvious to me that if 120VAC is giving me a 40W output, then, say, 60VAC should give me half of that, but it's rarely that straightforward. Given that it's a cheap piece of crap, the idea of monitoring the temperature seems a little out there, but a calculation on input voltage/current vs output power should get me somewhere, right?

Now, I'm asking this question as a (for now) hypothetical "what if". I don't have a variac, or any way to test my theories, I'd just like to know if something like this is possible.


texts: Connect anti-static wrist strap to earth wire?

texts:
I have started doing some hobby electronics at home and got myself an anti-static srtist strap recently.

I am unsure as to where to attach it to. Most topics I found online regarded PC building and attaching it to the PC case, but I want to use it while handling other things as well, mostly I am scared of killing my raspberry Pi. Since I live in Europe, one idea I had was to attach the clip to the earth connector on a Schuko (3-prong) outlet. But I'm not sure if it would be on the same potential as my pi or other things.  And what happens if that clip comes off?

So is it safe to attach it to the ground wire? If not, where else can I ground myself?


texts: Why voltage multiplier decreases current?

texts:
As far as understand, a voltage multiple increases the voltage but decreases current.
Can someone please explain why current decreases?


texts: ATTiny13 -- avr-gcc Hello World uses over 100 bytes?

texts:
I'm trying to write a program for the ATTiny13. My problem is that it has huge size constraints. Well, when making my first Hello World program, it took 100 bytes of program space just to make a light turn on and off! Are there any options I can give to avr-gcc to shrink this size down? Also, what is in the crt0? I'm not too keen on AVR assembly so I don't understand it much..

I do not want to have to drop to assembly for this project..


texts:
I am looking for a pneumatic valve and I refereed a catalog. It has a power saving circuit in the valve and there is a circuit diagram and description of that.
I couldn't understand how this power saving circuit works. Below is the description about that as the catalog.

Can someone explain about function and how it saves power ?
This is the full catalog. ( See page 44 for above description)


texts:
Electrical wire crimpers available on Amazon Canada tend to list die sizes in mm2.   This one cross-lists them in AWG, but there are some discrepancies between these sizes and the mm2 equivalent of those AWG sizes.

die size (mm2)  listed AWG     AWG equivalent in mm2
----------------------------------------------------
16              6AWG           13.3
25              4AWG           21.2
35              2AWG           33.6
50              1/0AWG         53.5
70              2/0AWG         67.4
95              3/0AWG         85.0
120             4/0 - 250 MCM  107.2

Why is there such a large discrepancy?  Will this tool actually be usable for crimping wire of standard AWG thickness?  Other tools listed on Amazon also include this same set of die sizes (or a super- or sub-set).


texts: Which could be the best solution for Wifi Card for a project

texts:
I'm new so sorry if my title isn't the best. I wanted to know (as I google it and didn't find a satisfactory answer) where can I find a Wifi Card connection for a project.

I have a little device I have been designing, and now I want it to communicate via wifi, since I did it with PIC and Arduino, I already find a MicroElectronika and Arduino WIDI Shield, but both are too expensive for my project so I wanted to know if someone had used another option for it, I'm just asking for the link and if it has documentation.

Thanks in advance


texts: PIC16F1827 Capacitive Touch Sensor not Incrementing Timer?

texts:
So I have a PIC16F1827 on a breadboard and was trying to get a simple demo working where I touch a wire to turn on an LED using the Capacitive Sensing Module. I was primarily going off this example I found, cross-referencing section 27 of the datasheet to make any corrections. However, despite my best efforts it wont do anything. From what I can gather the Timer1 isn't incrementing at all, just sitting at 0. Can someone help me figure out what I've screwed up here?

int count = 0;
int thresh = 0;

void main(void)
{
    // initialize the device
    SYSTEM_Initialize();
    SWDTEN = 0;

    TRISA1 = 0;
    RA1 = 0;
    // Set B5 as analog input
    TRISB5 = 1;
    ANSB5 = 1;
    // Set CPS module as Timer1 clock source
    T1CON = 0b11000100;
    T1GCON = 0;
    // Set CPS range to high and channel to 8(B5)
    CPSCON0 = 0b10001100;
    CPSCON1 = 0b1000;

    TMR1ON = 1;
    TMR1 = 0;
    __delay_ms(16);
    TMR1ON = 0;
    thresh = TMR1 * 8 / 10;;
    TMR1 = 0;
    TMR1ON = 1;
    //SWDTEN = 1;
    //SLEEP();
    __delay_ms(16);

    while (1)
    {
       TMR1ON = 0;
       count = TMR1;
       RA1 = count < thresh;
       TMR1 = 0;
       TMR1ON = 1;
       //SWDTEN = 1;
       //SLEEP();
       __delay_ms(16);
    }
}


texts: Verify Total conversion time of ADC1 STM32F303

texts:
I am using ADC1 channel1 of STM32F303 in Time triggered mode.  TIM1 is used to generate update event and is used as trigger source for ADC1. Time Trigger comes at 1kHz. I want to verify the total conversion of ADC. In F3 reference manual, it is mentioned that the maximum ADC clock can be set to 72Mhz. ADC is set in Asyhchronous clock mode and PLL clock 72Mhz (RCC_ADC12PLLCLK_Div1) is configured.

Sample time: 7.5 cycles
Resolution: 12 bit

Calculated total conversion time: sample time + conversion time = 7.5cycles + 12.5cycles(for 12 bit) = 20 ADC clock cycles.

For ADC asychronous clock = 72Mhz: ((1/72000000)*20cycles)= 0.2777 us
Tried to verify the same in Oscilloscope: I am enabling a GPIO pin to high in Update interrupt,and the same GPIO pin is made low in ADC EOC (EOC flag check) interrupt. The On time of the GPIO pin : 1.48us;
For ADC asychronous clock = 12Mhz: ((1/12000000)*20cycles)= 1.666 us But in the scope it shows as 2.08 us.

Suggest how to verify the conversion time.?


texts: I was reading about Intermediate Frequency on Wikipedia, and it says that if the IF is too high, it can cause clock jitters.  This is the first time I hear about this, and I cannot find any references that would explain this.  Does anyone know why this happens? -- or alternatively, where I can find more information about this?


texts: usb2 specification - is it backwards compatible

texts: Say I had usb port on my motherboard that only supports low speed devices, will full speed/ high speed devices not work on the low speed ports but at a lower speed?


texts: What's the best starting point for rotor angle estimation for FOC?

texts:
I'm driving a BLDC motor with FOC.  Right now, I have Space Vector modulation working, where I can give it a magnitude and an angle, and the algorithm will drop the right values into three PWM registers.  If I slowly increase the angle argument and call the SVM function periodically, the motor will spin (slowly) open-loop.

I am currently feeding a contrived angle into the function, but in practice I need to know the rotors position so I can perform all my clark/park/PI transform calculations relative to the rotor's angle.

I believe this can be done via a current observer, in which I feed back an error estimate to a SW-implementation of the HW-motor, and thanks to gains and high feedback, I'll be able to drive the BEMF estimate to zero and extract the angle information...But, I'm not sure if I've got that right!

I've read several application notes from TI, NXP, MicroSemi, Microchip as well as Dave Wilson's excellent video series 'Teaching Old Motors New Tricks', and I must say, the terminology and different flavors of doing this have got me a bit confused as where to go from here.

I am trying to go all sensorless by reading shunt resistors off of phase A & B....The current observer/BEMF estimator should be able to close the loop as sufficient speeds, but I'm not sure how to implement that, because it looks like it also needs the Clarke-Park transforms and PI controller to be working...But, I can't get that stuff working if I don't know the rotor angle.

What is the most sensible way to proceed with this development cycle?


texts: What is "Supply Input for Analog Functions" on a buck converter?

texts:
Regarding this datasheet for a DC Buck Converter, there is a VCC pin that on pg-2 shows an arrow pointing "out". What is this "out" connection arrow used for in practice?

Further along on the datasheet (pg-12), they show a board layout with that pin connected to GND via a capacitor. Is that a viable way to connect this converter if I don't have a use for whatever that "out" arrow is for?


texts: Lattice Diamond — How to identify which parts of design take most of FPGA resources?

texts:
I have a Lattice FPGA-targeted design which already takes approximately 95% of the SLICEs available on the device; pretty close to the chip capacity. Unfortunately, I need to add some more logic to it, so I have to optimize things a bit. But how do I identify the most problematic parts of the design? Neither “Network Analyzer” nor “NCD View” tool can give me such data. The best thing I found so far is to filter the NCD View list against a specific module name and manually count all the cells it shows. I believe there must be a better way.
Did I overlook some obvious option or dialog?
Can Lattice Diamond generate a detailed report on device utilization?
Related question (specific to the Xilinx software):
How to identify areas of a FPGA design that use the most resources and area?


texts:
Can someone please explain me the difference of n-channel enhancement, n-channel depletion and p-channel enhancement, p-channel depletion because I am confused.
Correct me if I am wrong but the n-channel/p-channel indicates the charge of the channel formed between the source and drain?
Thanks in advance


texts: Protection from leaking capacitors - store upside down?

texts:
I collect many vintage computers.  Most of them use through-hole capacitors, some axial, etc.  Some also use SMD caps.

When I store my computers, I always remove any batteries.

Anyway, I was wondering if storing my computers upside down would reduce the chances of a leak causing damage to the computer.

I realize capacitors leak.  Even while in storage.  But if it were upside down, it seems that the electrolyte would run down the side of the cap (onto the plastic top case, mind you).  Obviously, a SMD cap or any cap that is flush with the board would still get some electrolyte on the motherboard.  But shouldn't it be reduced to a smaller area?

Or, is this a crazy idea that has no real advantages.


texts: Increasing amplifier power to increase sound level

texts:
I am reading a book by Everest and I dont understand one of the paragraphs:

  Increasing amplifier to achieve higher acoustic level can be frustrating. Doubling amplifier power from 1 W to 2 W is a 3dB increase in power level, but this yields a very small increase in loudness. Similarly an incerase in power level from 100W to 200W or 1000W to 2000W yields the same increase in level.

What I dont understand is that how can an increase in power level from 1000 W to 2000 W have the same increase in loudness effect as from 1 W to 2 W ?


texts: Difference in real diode characteristics vs shockley equation

texts: I was wondering about the voltage drop in real diodes (0.7 V in Si diodes, 0.3 in Ge diodes etc.). According to my experience this drop is linked to the used material, but the shockley equation which should describe a diode never uses any material constant. So, how is the material constant introduced in a diode equation for modelling the additional voltage drop compared to an ideal diode?


texts: Where is the location of the reflected impedence?

texts: If I want represent the reflected impedance where should I put it in the circuit ?


texts: How do variable current limiters work in power supplies?

texts:
Bench top power supplies often enable you not only the set the voltage, but the maximum current.

How do these bench supplies provide this variable current?


texts:
When I come across RF circuit design books there is term know as simultaneous conjugate match but I can't understand what it is ? This was the statement I interpret with

**
Optimum power gain is obtained from a transistor when yi and yo are conjugately matched to YS and YL, respectively. As was discussed in Chapter 5, however, the reverse-transfer admittance (yr) associated with each transistor tends to reflect any impedance changes made a tone port back toward the other port, causing a change in that port's impedance characteristics. This makes it very difficult to design good matching networks for a transistor while using only its input and output admittances and totally ignoring the contribution that yr makes to the transistor's impedance characteristics.Even though YL affects the input admittance of the transistor and Ys affects it's output admittance, it is still possible to provide the transistor with a simultaneous conjugate match for maximum power transfer (from source to

**

load) by using the following design equations:
But this was the statement given in the book RF circuit design by Christopher Bowick


texts: Why does Channel Length Modulation Increase with Higher Vgs

texts:
I'm curious as to the physical reason as to why the effect of channel length modulation in an N-MOS actually increases when the Vgs voltage is increased?

See the plot below:

For a long channel device, as the Vg is increased, the R0 is actually decreasing. This makes sense if you think about channel length modulation as the inverse of the slope of the Ids-Vds in the saturation region, and that all of these slopes have to intersect at the early voltage.

But physically why does this occur?


texts: Piezoelectric coefficient modes 31 and 33 - What's the difference?

texts:
I'm having a hard time understanding the difference between model 31 and 33.
I understood it as follows:
These terms are ratio of strain with applied field, whereas the indices represent the direction of stress which causes strain in one direction and direction electrodes.
In 31-mode the external vibration force or stress working on X axis, normally labeled as (1 direction) while the output voltage is measured from z axis normally labeled as (3 direction).
I did not understand the explanation was: in this case, the voltage output should not be on the axis at the ends of the part? (referring to model 31).
me reading about the material of the subject it was not clear that.
if anyone can make a better explanation.
Souce: There are two prominent modes of operations applicable for MEMS piezoelectric micro power generator, which are 33 and 31 modes. In 31-mode the external vibration force or stress working on X axis, normally labeled as (1 direction) while the output voltage is measured from z axis normally labeled as (3 direction).
On the other hand, within 33-mode of operation, the external vibration force or stress and output voltage is measured on the same z axis normally labeled (three direction) as shown in Fig. 2. In a PMPG design, a cantilever beam with 33 mode of operation is preferred due to its bigger open circuit voltage leading to maximum power generated in comparison with the same device material, dimensions, and thicknesses on the 31 mode of operation (Jeon et al. 2005).
TECHNICAL PAPER : Design and optimization of cantilever based piezoelectric micropower generator for cardiac pacemaker.


texts:
I've been working on m66 and got it connected to PC via usb to serial converter, and got it up and running.

AT

command replies with OK response.

But none of the bluetooth commands are working.

In reference to Quectel_GSM_BT_Application_Note_V1.1.pdf provided by Quectel.

I've tried

AT+QBTPWR=1

but it replies with an error code

+CME ERROR:100

I looked into all reference documentation for this module, but cannot find any refernce to this error.


texts:
UPDATE:
I have removed switch and shielded cables and improvised the board as shown in below image. The transimpedance amplifier is stable. I applied four signal of 10kHz, 1kHz, 1Hz and 100mHz of 200mVpp and it's working without any oscillations.

So, culprit is the switch.I believe, somehow, switch adds up the capacitance in the feedback path and because of that the transimpedance amplifier was oscillating. now question is how can I minimize its effect on the transimpedance amplifier?

I don’t have experience in hardware design.
I am developing a system to do impedance spectroscopy where I am generating and applying sine waves in the range of 100mHz to 40kHz of 100mVpp-200mVpp to an electrochemistry cell, then reading the current through an I to V converter and then I will calculate the impedance.
I have an issue with the I to V converter. When any signal except DC is applied, it oscillates around 2.6MHz.
The conceptual circuit is given below. I am using the ADA4530 (datasheet) transimpedance amplifier. I am setting the gain and compensation capacitor through analog CMOS octal SPST switch ADG714 (Datasheet) for reading the current in the range of few micro-amps to few milli-amps.

Feedback resistors are as follow: 100, 1k, 10k, 100k and 1M ohms and capacitors are as follow: 2.4pF, 24pF and 2.4nF.  Please note that ON resistance of the switch is around 2ohms and it has source and drain on and off capacitance as follows:

The ADA4530 transimpedance amplifier  has input capacitance of 8pF and GBP is 2MHz with phase margin of 62 degrees.
For testing, I have generated 500Hz square wave of 800mV and applied to one end of the 100k (load) resistor and other end of the resistor is connected to negative terminal of the transimpedance amplifier which acts as virtual ground.

I have measured the signal at the input and output of the transimpedance amplifier.
The orange signal is input and yellow one is output (both signals are not out of phase with each other, I messed up delay in oscilloscope.)
The transimpedance amplifier oscillates just like this irrespective of any input signal except DC. I have selected different feedback resistors through switch but the problem still persists. When I measured this signal, I had 100k feedback resistor and 2.4pF compensation capacitor.

I have kind of reproduced this issue on LTspice, but the feedback capacitor looks unrealistic. Please note that while testing I have also selected feedback resistor without any feedback capacitor and thr problem still remains. So, I think it is a problem with the layout. Somehow input, output capacitance and capacitance on feedback path seems to be looks like values in LTspice and they seem to be unrealistic.

The below image is of layout of I to V converter and analog switch. I have guarding on TOP layer and 3rd layer and both guarding is connected through ‘via fencing’. The bottom layer is solid ground. I have measured guard voltage which was 230mVpp of around 2.7MHz.

The setup looks like this

Please help me out. Please let me know if you need any further information.


texts:
I am trying to understand Differential Manchester Encoding. The way I understand it is that the representation depends on the previous bit. If the previous bit was 0 there is a transition, but if it was one there is no transition.

Given that, would the following be correct?


texts: Why is it that current pass from charger to battery while both of them have the same voltage?

texts:
Why is it that the charger stops charging when the battery is full?

I answered myself that the battery is like a variable resistor and when it empty the resistor is low and when it full of energy the resistor is high but I cant solve the problem that why the current pass when both battery and charger have the same volt "we know that the current pass from high to low volt"


texts:
I want to find out the value of R2, R3, R4, R5. How can I solve it? anyone can help me?

For JFET1 VGS=0v, VDS = 15v.
For JFET2 VGS=1v, VDS = 18v.


texts: How can I connect a flat flex cable to pins of Arduino/RPi?

texts:
Touch panels seem to have a connector that has thin lines on a thin film.

Factories should have sophisticated machines to do such thing, but what about for individuals at home? If a person wants to connect such a thing to an Arduino or Raspberry Pi, is it possible? I wonder if there is some kind of adapter that makes the printed lines into common pins.


texts: acknowledgment size for STOP-AND-WAIT protocol

texts:
I looked frame size range calculation for stop-and-wait protocol post but I have a similar (?) question.
The question states.
A channel has a transmission speed of 10 kbps. The transmitted frames are sized 550 bit and the propagation is 20 msec. Errors do not exist. Since STOP-AND-WAIT protocol is used how large should the acknowledgment size be in order to have 55% efficiency?

I read that the efficiency type is efficiency = Tdata/(Tdata + 2*Tprop) and Tdata = DataFrameSize/transmission speed.

Solving that i find that the efficiency is 57%.

So the question asks how the frame size changes in order to have efficiency 55%?

If yes, doing the math that should be 488,88 bits,right?

Am i right or the question asks something entirely different?


texts: LDO layout: position of output cap relative to load

texts:
simulate this circuit – Schematic created using CircuitLab

In above figure, "LDO layout A" and "LDO layout B" are indicative PCB layouts of an LDO - focusing on its output capacitor.

"A" refers to a layout where trace from OUT pin of the LDO hits C1 first and then goes to the load VCC pin.
"B" refers to a layout where two separate traces originate from the OUT pin - one going to C1, and the other going to the load VCC pin.

The LDO is LD1117-3.3V and the max current consumed by the load is 100mA. C1 is an electrolytic capacitor. The width of the power traces is 32 Mil. The length of the trace from C1 to LDO-OUT pin in layout "B" is ~200 Mil. The VCC pin (load) has its own 0.1uf decoupling cap, placed closed to the VCC pin.

Are there any drawbacks of using layout "B" (two separate traces from the OUT pin of LDO)? I would have preferred "A" but due to board constraints, if I have to go with "B", what would be the consequences?

Thanks.


texts: How to create a noise budget and what to do with it afterwards?

texts:
While reading some questions/answers on this site, I came across this answer from Scott Seidman and I found it interesting.

  So, work out your noise budget, figure out how many bits you need, and do what you need to get them. Try to remember that an engineer who consistently exceeds specs instead of meeting them is wasting time and money.

How do you create a noise budget, and when you have one or are given one, how do you use that to determine what components you would need (opamps, adcs etc..) ?

For instance, if you are given a noise budget, how would you determine how many bits you need for an ADC ?

edit
Original link ratiometric ADC, is it feasible to separate reference voltage and excitation voltage by an amplifier


texts: How to use the SET_TRIS_B function in PIC C

texts:
Suppose I want the following settings

B7 B6 B5 B4 B3 B2 B1 B0
0  0  0  0  0  1  0  1

I want B0 and B2 to be input and the rest to be output so I did the following

 set_tris_b(0x05);

This does make B0 and B2 Input but it also does not make B5 and B4 have a high logic level by default instead they have low logic level? Why is that ? Am I doing something wrong ?


texts: Digital Compass identifying direction of travel for use with trains

texts:
I work in a control center for a train company in the UK. Our trains work in either direction but only one end has first class carriages. Because trains on our network reverse quite a lot it is difficult for us to track and advertise where first class will be.

Is it possible to create a device using a digital compass that will identify whether the train is travelling North or South and that can push this information via a GPRS transmitter so that it can be read on a PC? The device would be positioned at the first class end of the train with North pointing forwards. In theory If the compass direction is north and pin also north we would know that first class would be north facing. If the compass read out was south first class would be south facing.

I presume the main difficulties with this would be transmitting the information being read from the compass. Can anybody offer a solution?


texts:
I have a ceramic capacitor that reads "101 Suntan" (and nothing else.) Reading up on how to interpret capacitor labels, I believe this capacitor is 100pF. I'm having difficulties trying to determine its tolerance. All of the information I have read says there should be a letter designation which determines the tolerance, but there is none.

Generally speaking, what is a capacitor's tolerance if it has no letter designation? or can this vary between manufacturers?

If there is no rule for capacitors lacking a tolerance label, does anyone happen to know the tolerance of my specific "101 Suntan" capacitor? I think the Suntan TS15 datasheet is the one I want, but I'm not 100% sure. Also, I'm not entirely sure how to read it.


texts: How to analyze analog circuits with transistors [is this circuit immediately analyzable to anyone]?

texts:
I'm not experience in making electronics, but I do have a working knowledge of basic circuit laws and such, but we never covered something with transistors such as this BFO metal detector circuit I've been making as a weekend project:

This metal detector is relatively weak and I wanted to improve it a little, but I can't get a grasp on what this circuit in particular is doing. I see 2 oscillators on the left, but they both have transistors in them, and I'm not sure what that does to them. I put them in a simulator and they didn't do anything.

I understand the way this works is supposed to be based on heterodyning. So I'd like to make my reference oscillator, a detector oscillator, then multiply the signal somehow and feed it to my speaker. The speaker will only be able to pick up the lower frequency, difference signal, but that's the one I want. I have no idea how this circuit is doing that.

If this circuit is easy for you to figure out, is there a resource you could direct me to so I can learn how it works as well?


texts: BGA escape via dimensions at 0.8mm pitch?

texts:
Are there any kinds of standards or common practice dimensions which define what BGA escape vias and routing trace/space should look like at 0.8mm pitch? If not, what's the most economical set of dimensions to use?

Several documents I found when searching online discuss vias and routing dimensions on the top and bottom layers, but not inner layers.  As I understand it, the inner layers require antipad which makes them more restrictive than the outer layers. Therefore these should be the driving dimensions, but I can't find much on that.

I found a document BGA/PCB Interconnect Design Guidelines that discussed 0.8mm pitch (search for "0.8-mm"). It says that with a hole/antipad of 10/28 mil, only 3.5 mils remain on the planes and that isn't good. It goes on to say that using 8/26 for hole/antipad still leaves only 5.5 mil, and so you should just use microvias.

However, I see some manufacturers offer 8 mil inner clearance (antipad?), so couldn't you use 8 mil holes with a 24 mil antipad and have plenty of ground plane copper left?

I found this NXP document: PCB layout guidelines for NXP MCUs in BGA packages. It has a nice but very confusing table in it.  It shows generally standard hole sizes like you'd see from PCB manufacturers (12 mil, 8 mil, in mm) as drill size, and finished sizes way way too small.  The pad to drill size for 1mm pitch in particular would be an entirely normal sounding 12/21 via but the 'finished size' is 7 mil!  My understanding is that PCB manufacturers operate on finished hole size, not drill size.  What's wrong here?  (or with my understanding?)


texts: Pololu Carrier with Sharp GP2Y0A60SZLF IR distance sensor - mount it with hot glue

texts:
I want to mount the "Pololu Carrier with Sharp GP2Y0A60SZLF" IR distance sensor with hot glue to my robot. I can't mount it with the hole.

Is there any problem (like heat) to add hot glue on the sensor to mount it?


texts: where to insert a thermocouple simulator in a circuit?

texts:
I have a thermocouple that's connected through several runs of thermocouple wire into a USB adapter and into a laptop where it gets logged.  I'm seeing some error in my readings and would like to use a thermocouple simulator to calibrate.

The simulator has an input and an output.  Where should I put the simulator in the circuit?  Should it be as close to the bead as possible or as close to the USB adapter as possible?


texts:
i'm dealing with analog sensors. I have an Arduino Lilypad Simple Board with only 4 analog input.
Now, i need two more sensors and i've found on the net this schematics:

But i don't understand if it could add delays on my project because i'm controlling audio-video stuffs and any kind of delay has to be avoided.

Then, on the link i read this:

  It is possible to calculate the actual resistance from the reading but
  unfortunately, variations in the IDE and arduino board will make it
  inconsistant. Be aware of that if you change IDE versions of OS's, or
  use a 3.3V arduino instead of 5V, or change from a 16mhz Arduino to a
  8Mhz one (like a lilypad) there may be differences due to how long it
  takes to read the value of a pin. Usually that isn't a big deal but it
  can make your project hard to debug if you aren't expecting it!

I'm not a big expert of arduino and i don't understand what do i have to change for lilypad.

Any advice could be appreciated!


texts:
In may project I input a AC voltage to a transformer, the same input may have DC voltage, so i am searching for a way to disconnect the transformer form the circuit ,like a AC detection circuit to make ope of the transformer input open.

The following is a way i just write, i hope we could assets my to improve it or correct it if it is wrong, >> It is the first time i deal with this ICs and i don't know if they works as I suspect or not.

basically i will use a triac form my input to the transformer and i will use a AC voltage logic sensor to detect if my input is dc it will turn the triac on and if a DC voltage applied it will stay off.

As I say, I am not sure if the ICs do the function I required or not.

MID400 datasheet
MOC3061M datasheet

Mr.Andy aka solution


texts: How to immediately turn WS2812 LED strip on after power on?

texts: I built a table lamp with a 1m WS2812 LED strip controlled by a RPI Zero W. It has a decent power supply that outputs 5V directly to the LED strip and also powers the RPI. The RPI takes approximately 25 secs to boot on power up and after that it sets the LED strip. This is way too long. How can I make the LED strip start immediately as it receives power and then let the RPI take over?


texts:
I'm designing a new circuit and I need to know if PC817 allows AC voltage input around 230V.
I've tried with DC Voltage but never AC Voltage.
Does anyone know if it operates with AC input?


texts: How can I generate random numbers in verilog using clock speed?

texts:
Suppose I have clock 50 mhz and I want to generate a random number between

1 - 13 (inclusive both)

Suppose when I click a key, then I want a random number between 1 - 13 generated.

My idea:

Click Key

-> (take last 4 digits of clock MOD 13) + 1

I'm not sure how I can access the last four bits of the clock?


texts:
What is the difference in this two different 3-winding transformer ?

Will the second one work ? Why or why not ?
I am really confused with both this circuit. Please help me with this.


texts: How do I specify 3 interrupt transfers per microframe in high-speed USB?

texts: I am sending interrupt transfers over USB 2.0 and trying to get the maximum bandwidth possible.  According to various documents, they indicate that "the endpoint descriptor may specify up to 3 interrupt transactions per microframe".  I can't find any way in the endpoint descriptor to specify this.  Anyone know how?


texts:
I am working on something that I'd like to have a backup battery source for some of the components, it's going to be on a 5V circuit, but everything that needs to be backed up should tolerate anything down to 3V fairly well.

It is all fairly low current, probably under 100ma and wont need to last all that long, so I was thinking about using a single 18650, and when I was looking into doing float charging, I saw that you could do it, if you kept the voltage on the cell low.

I went with this chip for my voltage regulator Digikey Datasheet

By using a 42 ohm 1w or 1/2w resistor, I should limit the current going into the battery to 100ma, and by putting a diode coming out of the Battery to the rest of the circuit I will prevent any accidental charging of the battery from elsewhere, is there anything I'm missing?


texts: Help identifying a varistor from a fluorescent light tube ballast

texts:
I am trying to identify the blown varistor from my fluorescent light tube when I was trying to fix it.
I have never seen a manufacturer marking logo on it with a "W" and a cross in the middle. Not sure what the "P050" means but I think "250" could be the voltage tolerance.
It'll be a great help if somebody knows what the specifications are.

I found the part for the Dark Red capacitor to replace it.
The diameter across the varistor is about 7.5mm in diameter.
The varistor is across the input supply.
I'm not quite sure for the voltage rating of the ballast probably 220V...? I'm in a European country.


texts: I have interfaced a 12 V pump and a 12 V fan to LPC2138, there are 3 5 V sensors interfaced, according to which the fan and pump function. The whole setup is in PCB. There is a ESP8266 module interfaced to controller. The decision to switch on or off these output devices (fan and pump) is given through the server end( WiFi connectivity). The problem that I am encountering is that whenever both the devices that is the fan and pump switch on together, the whole circuit either disconnects, or resets or the stops functioning normally (LCD displays vague values), what should I do??? Please help. The whole system is powered by a on board PCB voltage supply, where a 0-12V 1A transformer is used and voltage regulator ICs (plus design which includes rectifier, capacitors etc) are used to divert 12V, 3.3V and 5V dc supply voltages.


texts: What causes a distortion in the output characteristic at low Vds?

texts:
Attached are the output characteristics of two different LDMOS transistors, extracted from TCAD simulation, where Vgs = 3.3V.
The output conductance clarifies the distortion more.
What are the causes of this behavior? Any recommended literature for a detailed explanation?


texts: Use USB-C alternate mode pins for custom signals?

texts:
I am working on a product that is made of 2 parts: a host with a male USB-C connector and a device with a female USB-C connector that plugs onto it.

The plan is to use USB-C because it's a nice reversible connector, but we'll only use the USB 2.0 specification and pins. We want to use the unused "Alternate mode" pins (in blue) to transmit our own signals.

If I do, what happens if the consumers plugs the device to his computer using a USB 3.0 USB-C cable? Will the host detect that the device is simply USB 2.0 and will not use the Alternate lanes? Or could this cause hardware damage somehow? What resistors should I put on CC1/CC2 pins?


texts:
I am designing a discontinous conduction mode flyback converter, 100kHz using UC3844 IC with the spec. 220V,50Hz to 5V 5A. The issue is that after testing it for an hour, the transformer starts heating up (tried with different cores.)
Ambient temperature: 27degC
Transformer specifications:

1st try: EE20/10/6 core, 0.5mm gap, Al=100nH/turns2 (EE20/10/6 Datasheet)

Turns ratio: 21 to keep Vds(max) low

Primary: 1.7mH, 30 SWG, 130 turns, 1 strand

Secondary: 5-6uH, 6 turns, 30 SWG, 7 strands (I know, the diameter that I used is very low but could fit only this in the winding area and the strands have to be increased, for testing purpose designed this)

Auxiliary: 52uH, 14 turns,30SWG, 1 strand.

With this configuration, the transformer was heating up to 80deg C in just 30 min.
From the calculations for the core loss, it was coming to 170mW, but copper losses were huge
Primary: Irms=0.4A, Resistance_dc=(total length)Res. per length, Rp=(7.64130)0.221 mOhm=873mOhm, P=0.40.40.873*1.5=0.2W.
Secondary: Irms=9A, R_dc=(7.646/5)0.221=8mOhm, P=99*.008*1.5=0.972W(This is the prob)
Seeing this with the thermal resistivity of 50K/W, the temperature would rise to almost 80 degC. So, it confirms the problem.
I could not fit more diameter winding on this bobbin, I had to increase the core size.
2nd try: EE25/13/7 0.2mm gap Al=290nH/turns2 EE25/13/7

Same inductance parameters.
Primary: 77turns, 30 SWG, 1 strand
Secondary: 22SWG, 5 strand, 4 turns.

But even then it is still rising to 65-70degC.
Currently working at 78% efficiency.

What is happening in this case?
Are my previous calculations correct?
Is it because AC resistance has increased due to skin effect since operating at 100 Khz because of 22SWG wire, or something else?

Edit:

3rd Try:
EE25/13/7 core: 0.4mm gap, 187nH/turns2 [earlier(340nh/turns2)]

Primary: 30SWG, 1 strand, 95 turns, 1.6mH
Secondary: 22SWG, 5 strand, 5 turns, 5.2mH
Auxiliary: 35 SWG, 1 strand, 16turns.

Although the temp decreased but still hovering around 65degC.

Circuit diagram:


texts: i2C multiplexer to use multiple sensor of the same type

texts:
I would like to hook up multiple sensor of the same type (temperature, pressure and so on). The problem is that each sensor can only have 2 different unique values for the register, so can't put more than 2 on a single I2C bus.

I would like to multiplex the I2C channel; so I can plug more sensor; altho I do not know

What kind of breadboard to get (found few store online that has analog multiplexer; is that OK for my case?)
What kind of code should I write? Do I have to ping each sensor in a sequential way? is there an example about how to cycle trough various sensor using a multiplexer?

I use an Arduino clone board, called Teensy; but I saw also a nice clone called Trinket pro; they both are programmed via the Arduino programming language; so any example would be really appreciated.


texts: why is this oscilloscope so cheap with a 20Gsa/s sampling resolution?

texts:
I've looked around this site but I haven't been able to figure out why this oscilloscope seems to have such a high sampling rate "Repetitive mode: 20GSa/S"  and be relatively cheap:
http://shop1.usbdso.com/MSO-9201-with-Logic-Analyzer-MSO-9201wla.htm

Can someone explain?

Thanks


texts: Acceptable conformal coating expansion ratio for PCB with delicate SMT parts?

texts:
I have heard that conformal coatings can put stress on SMD parts because of expansion/shrinking while curing or because of temperature differences. How much of a problem is this?

The only value relating to this which I found in the datasheet for the coating I'm looking at was "Cured film Coating: Coefficient of Expansion: 90ppm" which I guess is about expansion while curing because it has the wrong dimension for a thermal expansion coefficient. I assume this means that for a 20cm board there would be expansion of \$90\cdot10^{-6}*200mm=0.018mm\$ which should be negligible. Is this right?


texts: How does this power supply circuit work?

texts:
This is the circuit of a power supply with adjustable output voltage and current, and I wish to understand how it works:

What I did understand:

R1 T1 VD5 - they form a voltage divider which provides a voltage referrence that is applied through a voltage divider formed by R3 to the input of a common collector amplifier formed by T2, T3 and T4. This allows us to set a desired output voltage by varying the base voltage on T2.

R6 is used to create a voltage drop, to measure the output current, which is set by R8. To limit the current, T5 loweres the referrence voltage.

What I don't understand:

Is C3 used to filter fluctuations which occur too fast for the zener to react?

What is the purpose of R4 and R5? And what is the purpose of R7, C4 and C5?

How exactly does T1 work? And why does the LED only come on when the current limit is reached? It looks to me that it should be on all the time.

Sorry for my english. And I hope my questions aren't too dumb.

PS: Is it possible to replace the output transistors T2, T3 and T4 with a MOSFET?


texts:
Ok so I have burned about 10 MIC4605 (Datasheet here ) gate drivers this weekend. I am unsure as to how they should be PROPERLY wired.

Also have burned 8 out 10 MOSFETS (Datasheet Here )

Page 1 of the datasheet shows a typical application which is interesting because the motor I am using is 140mA @12V

So I wired it just like that...Magic Smoke came out
I tried to PWM the low side mosfet of one side of the bridge while the other side had the high mosfet activated. Things blew up.

So i figured this must be some sort of circuit diagram where "things are assumed" like schottky Diodes. After some research
I found this on Microchips own website and the funny thing is the circuit diagram looks a lot different than the datasheet.

So now I have this wired up and I am down to 1 Gate driver left alive after burning 9.
This circuit seems to work. I am not using a 24V bus, My motor and my gate driver are both being fed by a 12V coming from my power supply. In the circuit above I am not using the lowside mosfet, instead I am just testing the high side mosfet and my motor's other lead goes directly to ground.

This works just fine at 12V and I am PWM'ing perfectly fine and works well, until I turn the voltage up to 16V and then my driver dies.

My only guess is that BACK emf becomes too large and kills something, but I have all the diodes in the schamtic in their rightful place..

I am PWModulating at 32Khz.

My ultimate goal is a Full Bridge Motor driver with all N-channel MOSFETS and having atleast 2 Mosfets in parallel for each high side and low side, but i cant even get past one mosfet at a conservative voltage.


texts: Is virtual memory possible without an MMU? Can a kernel be written to create software-based virtual memory? If none of this is possible, why is that so?


texts: Why are both the voltmeters in the circuit showing the same. The blue one should have triple the voltage. What's wrong in my circuit?


texts: What is the reactance when the frequency is 80 kHz?

texts:
I recently had a test with the following question:

  What is the reactance of a 6.8µF capacitor at 80 kHz

I found the reactance to be:

\$X_c=\frac{1}{j \cdot 2\pi \cdot f\cdot C}=\frac{1}{j \cdot 2\pi \cdot 80 \cdot 10^3 Hz \cdot 6.8 \cdot 10^{-6}}=0.29 \Omega\$

However, I got a "wrong" on this answer but the instructor didn't give me the correct answer to the problem.

Can anyone explain to me what I did wrong, and what the correct answer should be?


texts:
Say I have a parallel plate capacitor that has a vacuum between the plates and has electric energy U. If I then add in a dielectric between the plates while the capacitor is charged, the electric energy increases since the dielectric constant increases.

But where does the additional energy come from? Doesn't that violate conservation of energy? I understand that the energy is increased because the permittivity of the dielectric increases, but doesn't it still violate conservation of energy?


texts: Transimpedence amplifier, higher output than expected

texts:
I am approaching now at LTSpice.
My aim is to design a transimpedence amplifier in order to have V_output=I_input*1000.I mean,such an easy task.

So I tried to run my simulation, also adding a capacitor of C=4pF (obtained  considering gain bandwidth of 4MHz).
What I expected was to obtain an output voltage equal to 0.005*10000=50V (and that is what it happens if I use the ideal on e BUT I have to use this opamp (https://file.didattica.polito.it/download/MATDID/32964544) and the result is the following.

I really don't know why it shows this voltage and how to fix it! Please help me, thank you!


texts:
I'm building a IR hub to control several LEDs stripes, and a projector in a room and noticed that my IR transmitter works even when VCC is not connected.

Should I wire it in anyways? Why is it there? What does it do?

This is the IR transmitter I have.


texts:
Could you please tell me what is the purpose of this highlighted part of the circuit? This is from a Soundtech 6150 powered audio mixer.
This specific mixer is outputting the supply voltage and has already burnt a speaker. The transistor on the top-right side of the highlighted area (C104 if you can read this old manual) is heating up quite a bit as well. It is likely that the parts in this circuit are not the original ones.
Thank you for your time!


texts:
I tried building a basic power supply on my breadboard using the schematic for SparkFun's Breadboard Power Supply (https://www.sparkfun.com/products/8376).

My setup is:

Hooked up 10uF capacitor to VIN and GND
Hooked up 0.1uF capacitor to VOUT and GND
Hooked up GND and VOUT to the voltage rails on the breadboard
Hooked up Arduino UNO's 5v and GND pins to voltage rails

A Fritzing diagram is here: http://www.chris-cartwright.com/BadReg.fzz

This setup works fine without the Arduino load. Once the Arduino is connected, the voltage drops down to about 2.5v.

I'm not sure what is wrong with the circuit. My load readings are about 17mA.

I do not have access to an oscilloscope to check the circuit with, but I  don't think oscillation is my issue given how similar my circuit is.