texts: Current chopping with an h-bridge and PWM

texts:
I have some stepper motors and L298N dual h-bridge drivers. I can't find exact specs for the steppers,* but similar motors from another product line have rated voltages from 2.64v to 5.8v. Since most power supplies don't come at these exact values, it seems current chopping is necessary.
*Minebea, the company that manufactured the motors, says the motors were part of a custom order, so they don't have specs.

I had the idea that open-loop current chopping might be possible with PWM from the controller board (in this case an Arduino). Since torque isn't much of an issue, it should run fine without needing to compensate for changes in the back EMF.

Using soft PWM I was able to generate a 20kHz signal and could have gone much higher.

On page 4 of a datasheet I found for the L298N it lists a bunch of delay times (e.g. "Source Current Turn-off Delay"). Those values should be quite relevant here. Page 2 also lists the peak output current for different time ranges. I have a bit of concern there because the max repetitive current is 2.5A. If I'm reading the bottom of page 3 correctly the total voltage drop is at least 1.8v. What might the drop be at a higher voltage, say 12v?

The question is, it it a workable strategy to run a stepper at high voltage (e.g. 12v) by chopping the current by switching the h-bridge? I've only seen a couple references to doing this (here and here), though neither fully answers the question. I want to be sure this won't fry either the h-bridge or stepper.


texts: Resistor between GND and + 5V in Arduino

texts:
I design a board based on ATMEGA328P (as in Arduino UNO).
Now I am busy creating a power line. My controller will be installed on the electrical panel, so I need to provide a reliable, noise-resistant device.

Once in the examples, I saw a 180 ohm`s resistor that was installed between VCC and GND. What does this resistor give to the board? Should I use it?

I also assembled a chain of SMD capacitors (4 normal and 1 polar). Should I change the number of capacitors or their capacity?


texts: Regulated power supply 1,5-34 V ~ 40A using LM1084ADJ and TIP122

texts:
I would like to create a simple (not very fine tuned) regulated power supply in which with two potentiometers.

I want to adjust the voltage from ~2V-34V, while the output of my 24 V transformer rectified and smoothened with 10000 μF is about 35-36 V. I had the idea to just use approximately 8 LM1084 (5AMP) regulators in parallel and also have 8 TIP122 (5-8A) darlington transistors in parallel, steering their bases to regulate the power.
Is this at all feasable/doable?

One thing I realized is that short circuiting the LM regulator breaks them almost instantly.

simulate this circuit – Schematic created using CircuitLab

Obviously I only drew 2 of the 8 planned LM's and transistors and I did not implement the transistors correctly this way. Can anyone please tell me if this could make any sense?


texts:
I`m new to VHDL and i don't know how to write the testbench code for a 7495 register. I need to do this for a college project. Any help is greatly appreciated.

This is the Design Source code i`ve used for the register:

         library IEEE;
 use IEEE.STD_LOGIC_1164.ALL;

 entity ic7495 is

Port ( clk1 : in STD_LOGIC;
       clk2 : in STD_LOGIC;
       mode : in STD_LOGIC;
       ser : in STD_LOGIC;

       d : in STD_LOGIC_VECTOR ( 0 to 2);
       q : out STD_LOGIC_VECTOR (0 to 2));

     end ic7495;

     architecture Behavioral of ic7495 is

     signal qint:std_logic_vector(0 to 2):="000";
    signal clk: std_logic;

    begin

    clk<=clk1 when mode='0' else clk2;

    process (clk)

   begin

   if clk'event and clk='0' then

     if mode='0' then
     qint<= ser & qint(0 to 1);
    else qint <= d;
    end if;
   end if;
   end process;

   q <= qint;

   end Behavioral;


texts: Solatron giving incorrect value of capacitance

texts:
So I'm conducting an experiment with an impedance analyzer (AD5933). But for the experiment, I need a calibration impedance. I am calculating this calibration impedance using a Solartron. I put 2 parallel copper plates ( 8100 sq mm, with spacing of 40 mm) in a setup ( I stuck the copper plates to teflon blocks) and calculated the capacitance using the Solartron. When I put nothing in between the copper plates (air as dielectric), the capacitance values give me a dielectric of 1.2-1.75. However, when I put water in between the 2 plates ( I put a plastic bag filled with water and also put the entire setup in de-ionised water), I get value of dielectric that no way corresponds to the 70-80 that I should be getting (since water has dielectric of 70-80). So for water as dielectric, I get 1nF, whereas I'm supposed to get 143pF (if you calculate it theoretically). This is at 30kHz.

I have repeated this experiment and even asked my supervisor, but no one seems to be able to know what the problem is. Has anyone had this issue or can anyone shed some light on this?


texts: Combined series and parallel resistors -- adding resistors

texts:
Sorry for the poorly worded question, I wasn't sure how to make it clear

If I have a 100ohm resistor with two 100ohm resistors coming off of it (in parallel), is the total resistance 200ohms?

simulate this circuit – Schematic created using CircuitLab


texts: Why compass module is affected by its x,y position, if my phone's compass work in the same environment?

texts:
I am using hmc5883L on an autonomus robot. It shall remain in a 1 meter squared area. I have recently discovered that its reading changes up to 20 degrees on different positions even when it is facing the same direction (values are consistent within a given point though).

I believe there should be a magnetic field distribution in my room (a slight tilt might also exist for that matter). I am about to take this as a huge error percentage, however I really prefer not to. So I thought I may check if my phones (iphone) "compass" application will diverge 20 degrees as well. It didn't even diverge 1 degree.

So my question is, how is this even possible if such a magnetic distribution exists? Does phones use a different method to tell the position of north? Is there anything I could do to make my readings more consistent with changing positions?


texts: Measuring the instantaneous power consumption of phone

texts: We can get the instantaneous current consumption and battery voltage via Android's API. So if we multiply those things, can we get the instantaneous power consumption of device? (P=V.I)


texts: Can a 450 V AC starter motor film capacitor bear 300V DC?

texts:
I know AC and DC ratings for capacitor differ. But when it comes to film (polyester) capacitors and more in general non polarised capacitors, I ask myself if, given only the AC rating, it is possible/safe to use them in low current (<< 1mA @ 600V) DC applications.

In my case, I am building a one stage voltage multiplier and I need a capacitor (C1) rated to bear a steady state 320 V DC (since Us is 230V AC) and an initial charging transient under AC. I initially used electrolitic capacitors (10 series 63V 100 uF) and it works fine, however I wonder whether repeated turn on transients may damage the polarized electrolitic capacitors. I decided to try with a polyester capacitor used in AC single phase motors however I am having second thoughts on its ability to withstand DC.

So, in your opinion, is a 450V AC rated capacitor suited for C1 in this application?

PS: This is a test installation used in a controlled environment.

Additional info:

Low power application << 1 mA at 600V DC.
Mostly turned on and off a few times a day for a week.
Source is 230V isolated from mains using a dedicated insulation transformer

Datasheet is here (in download section. There is no mention of DC rating.


texts:
I'm a beginner. I'm designing a battery powered LED flashlight with a dimmer. The flashlight will have 3 LEDs and the dimmer will be controlled by a PWM signal generated by a 555. The circuit is powered by 2 AA batteries (3V).

This is the LED part of the circuit:

simulate this circuit – Schematic created using CircuitLab

So, my calculation is this: I'm applying a 3V signal through a 12k resistor, so the current being applied in the transistor base is 0,25mA. Since the 2N3904 (Q1) has a max hFE of 300, the current being sunk by the transistor is 75 mA. This current will be divided between the three LEDs, 25mA for each one, which is the rated current for this LED.

So, my questions are:

Are my calculations correct? Is my circuit correct?
This transistor has a hFE value between 100 and 300. I'm using 300 to be on the safe side. Is this correct?
Am I at risk of destroying the transistor or the LEDs? If one LED burns, the current will be then divided between the other two (38 mA each)?
Is this the most efficient way of powering these LEDs?


texts:
This is a picture of the PCB for a Tile Bluetooth tracker.

I cant find any info on this chip, and I've looked for a while for the logo. here is a closer picture.
The logo looks like three ticks, does anyone have any ideas? It should be some sort of RF front end for the Bluetooth.

Edit: I think The Photon correctly identified the logo as that of RFMD, but I'm still having trouble finding the exact part, especially since they got acquired

From what I can tell, Pin 4 is the connection to the bluetooth IC and pin 11 is the connection to the antenna. Pins 3 and 10 are connected to GND, and beyond that its not clear.

Finally found it! It's the RFFM6205, and the important code on the package is X8


texts: 1-row 0.1" pin spacing connectors with good connect/disconnect cycles

texts:
How can I locate connectors with a good rating on connect/disconnect cycle lifetime? (1000+ cycles)

I've tried searching on google, and I've checked a couple of Molex series I'm familiar with, no luck.


texts: MATLAB error: "acker" function not returning the same thing as ackermann's formula

texts:
I have a discrete time system

Suppose I have the following AB matrix of my system
$$A =
\begin{bmatrix} 0 & 1 \\
1 & 1.5 \\  \end{bmatrix}
$$

$$B = \begin{bmatrix} 0 \\
1 \\  \end{bmatrix}$$

To design a state feedback stabilizer, I want relationship $$u = Kx$$

where K is my feedback gain, u is input to my discrete time system

To design this, use well known ackerman's formula as follows:

  $$K = - \begin{bmatrix} 0  1 \end{bmatrix}*C^{-1}_{AB}*r(A)$$

where r(A) is my characteristic polynomial containing the pole I want to place

MATLAB directly calculates this using "acker" (and "place", but we will limit to one problem at a time)

But I keep on getting two different results and it is driving me crazy! I checked every single step!

Please help me to pin point the error in the following code:

%Approach 1: Raw formula

A = [0 1; 1 1.5]
B = [0 1]'
CAB = ctrb(A,B)
K1 = -1*[0 1]*inv(ctrb(A,B))*(A^2 - A + 0.25) %I wish to place the poles at {0.5, 0.5}

%Note (A^2 - A + 0.25) = (A - 0.5)(A - 0.5), the characteristic equation containing the two poles

%Approach 2: Using Build-in Acker

K2 = -1*acker(A,B,[0.5,0.5])

It is completely illogical to me why

K1 =

-1.2500   -0.7500

K2 =

-1.2500   -0.5000

I am using (in principle) identical way to calculate the K vector! Also note this error has never occurred to me in any previous designs before my system started blowing up all over.

Can someone who knows control theory pin point exactly what maybe the problem? MATLAB also contains bugs so that is something to be kept in mind.

Thanks


texts: Need for thyristors in power electronic circuits?

texts:
Can anyone tell me why are Thyristors(SCRs) used in power electronic circuits? How are they more  adept at handling power as opposed to other active or passive electronic components?

UPDATE:
As per the request made by jippie i am uploading the circuit diagram for a simple full wave rectifier to add a context.

(source: circuitstoday.com)

why should some one use SCRs in this circuit when the same action can be achieved using diodes?


texts: How to achieve desired output voltage and current draw from a hot shoe

texts:
I have very little knowledge of electronics, although I enjoy tinkering with basic electronics from time to time. If I have a battery of known voltage and I want it to light up a small 3mm led, I know I can use $V = IR$ to find out what kind of resistor. If my voltage is given, and I know what I want my current draw to be, I can simply solve for $R$ to find the resistor I would need.

I'm having trouble applying this to a hot shoe (the connections to a camera flash). I wanted to connect an led to the hot shoe and activate the flash for fun, like making my own diy flash. I looked up the power supply of a hot shoe so I can find the appropriate resistor, but it doesn't seem to have a single voltage. All I could find is "be careful not to let the circuit voltage over x amount" as if the hot shoe voltage can be changed the same way I can manipulate the current draw in my first example. So this leaves me confused at what to do. I know the resistance influences the voltage, but how can I manipulate the system to both a desired voltage and current draw?


texts: Objections to use an RCA connector for antenna in broadcast FM receiver

texts:
Due to budget & space restrictions, I am thinking about replacing a PCB BNC connector used to attach an external FM antenna. It seems to me an RCA connector could be an option, given its good shielding, low impedance and the (relatively) low frequencies involved. But I was unable to find better arguments for & against it in my searches, or any examples of anyone using it. Would it have a good (or at least acceptable) performance? If not, any recommendations?
BTW, the antenna at the other end is the typical monopole, 100R.


texts: Using a component footprint drawing as a guide in Altium Designer's component editor

texts:
Just copying a footprint drawing image from a datasheet, placing it as a temporary background guide in the PCB component editor, scaling it and using it as a rough guide in conjunction with the grid as a precise guide would make it much easier to create footprints. Is there anything of this sort possible in Altium Designer?

(The only thing I've found is an old image import script that converts it to primitives. But then I don't know how to resize the whole thing.

The only remaining alternative I can think of is one of these Windows Desktop tools that allow to make windows partially transparent so that the background can be in a different application.)


texts:
I have this project that requires some kind of backup power supply. and I am planning to use a 5V 4F super cap.

there are my questions:

I am planning to charge the cap with a diode and 100 ohm resistor to a 5V VCC (Good idea?). how can I connect the cap to the MCU. direct connection will not work because it will take some time for the cap to charge up.
Normally the circuit will consume 20mA, in power-off mode, it will use about 200uA, how long will this 4F cap last?


texts: When charging mobile decices using an external battery is DC > USB more efficient than AC > USB?

texts:
I bought a "jumpstart" battery that has a built in power inverter to support both AC and DC ports. I have it for a project but also want to use it for charging my mobile devices occasionally.

I do have an AC > USB adapter, but I'm wondering if it would be more energy efficient (read: save battery life) if I were to get a DC > USB adapter. My logic being that these small electronic devices use DC power and so there's no / less conversion when going from DC to DC.


texts: Driving line input of a speaker from a differential amplifier, why is the output clipped?

texts:
I have a differential audio signal which I want to use to drive a single-ended device (in this case, an amplified pc desktop speaker with line level inputs) with 10kohm impedance.  I have wired up a TLV2462 op-amp as a differential amplifier:

simulate this circuit – Schematic created using CircuitLab

The opamp power is 5v relative to ground, which is not connected to the amp ground in the circuit above.  The input common mode voltage is 0.75v, and the differential signal is about 0.5v p-p, so the inputs should be well within the rails.

If I put a scope between amp input and amp ground with the load disconnected, I see the output signal exactly as I want it (sorry for the bad cellphone pic of a cheap scope):

But if I connect the load/speaker, the output is clipped slightly below 0v:

I see exactly the same output if I just put a 10k resistor in the circuit instead of connecting the speaker.

Edit: In the answers and comments below, several people have commented on ground and amp ground not being connected.  If I connect A to ground, then I see basically the same as the second scope image below, but the clipping is actually at ground, not a little below it.  If I put a capacitor between amp ground and A (now ground) instead of connecting those directly, I get the output I want.  But, I don't really understand why.

Is the ground connection and capacitor I describe above the "right" fix?  Why does it work?  If not, what should I be doing instead?

Since this is for music, I'd like to keep frequencies above 20 Hz, if that's practical.  The impedance of the load is 10k.


texts:
So my friend and I were working on this project which required capacitors. We needed to charge a capacitor with the following rating: 100microFarad, 400V.

When we connected it to a 220V AC source (peak voltage 311V) it went boom. We thought we had somehow shorted the circuit and tried once again making sure that the connections were proper. Once again it went boom. What were we doing wrong? Our setup was simply a few wires and our capacitor.

EDIT

So I got why it blew up (the current surged). Now I'm editing the question to ask this:

So while we were in school, our physics laboratory assistant called up an electrician from downstairs to show how to do stuff. The electrician brought a ceiling fan capacitor and showed us how to connect it to the socket. Maybe he thought we were dealing with such capacitors too. So he charged the capacitor and took it out and touched its two ends in such a way that there was sparking (proof of charging). Why didn't this capacitor blow up? Current must have surged in this one too right? (Thank God it didn't blow up! The guy was holding it in his palms). There wasn't any considerable difference in capacitance (it was 1000 microfarad against the 100microfarad we used) so why didn't it?


texts: What are the qualities that you look for in a 2nd stage LNA?

texts:
We are building a multi-stage LNA for a TR module we are building in the 144MHz and 440MHz range.
The 1st stage LNA has to be the most sensitive---but what is important to consider when choosing a 2nd stage LNA?
This is the 1st stage LNA we are considering: Qorvo QPL9547


texts:
I have a Venus634LPx GPS on a breakout board from SparkFun. Read more about it in my previous question.

The configuration program gives me the option to configure "1PPS Timing":

Here I can choose between "Survey", "Static" and "PVT" (Position, Velocity and Time). The Venus838LPx datasheet talks about these modes, but not the Venus634LPx datasheet.

What do these modes mean? I find the datasheet confusing.
Is it something unique to the 838, or does the 634 also have these modes?


texts:
So I've been getting into the world of USB C and was wondering how hard it'd be to create a USB hub that supports the USB Alt mode for things like video. I've noticed there are USB-A hubs on eBay for very cheap, but I couldn't find anything like that for USB type C. I feel like it'd be pretty fun and cool to create my own and I think it could be significantly cheaper than some of the ones out there...
Thanks!

Also Sorry if this has been asked before!


texts: What is the purpose of the 7805 output capacitor?

texts:
How does a cap on a regulator output improve transient response? Is this cap not more appropriately drawn next to the load where it is not being defeated by intervening trace inductance? Or does this output cap serve a different purpose than the typical bypass caps seen on a digital IC power supply pin?

http://www.ti.com/lit/ds/symlink/lm340-n.pdf

Edit: This has been flagged as a possible duplicate. While the answers may have some overlap, the titles of the three questions I asked are very specifically different questions. This should be evident upon reading the Titles.


texts: Powerful driver circuit for small power stepper motor

texts:
i want to drive a small stepper motor, let's say nema 17 ( which is usually below 10 W ) with a big driver circuit that can run motors above 20 W.Can i use that driver and maintaining for a long period ( let's say 2-3 h ) underload ? My logic tells me that it should not be used for large stepper motor, that that driver couldnt deliver such a current and for small power it's ok, but anyway i want to be sure,

Thanks:)


texts: Does NRZ-I have a synchronization problem?

texts:
I'm new to EE, just have a question on synchronization.

I was reading a book which says:

  NRZ-I has no problem with sequences of 1s, but has problem with sequences of 0s.

It certainly has a synchronization problem with sequences of 0s. But for sequences of 1s, it is still possible to have a synchronization problem.

For example, if a sender sends 1111 and the receiver's clock is twice as fast as the sender's clock, the receiver will interpret the pattern as 101010.

Isn't that a synchronization problem?


texts: Generating 5V DC in an AC system without the neutral wire

texts:
This is my first foray into AC circuits, I've only worked in low voltage DC circuits before.

I am building an AC dimmer circuit with a wireless radio, a bit like this device and I don't quite understand how I can generate a 5V DC voltage without the neutral wire being present.

The AC to DC converter module I use requires both a live and a neutral wire connected:

In the product linked above they must have some form of DC voltage present for the radio circuitry, I am guessing.

How would I go about either wiring the AC-DC module without the presence of a neutral wire and failing/ditching that, what kind of a power circuitry I would need to get5V DC with just the Live wire being present?

Thanks.


texts: Will UA741CN as a comparator work below 8V?

texts: I wanted to create a comparator circuit with UA741CN which is only comparator/op-amp I have in my junk right now. I wanted to use it with 5V but no matter what is inverting ref voltage is giving any voltage to non-inverting output gives me always high as output. When I set the power supply to the 8V it works as it should be. Even in 7V it is acting weirdly as i said so. What might be the problem here?


texts: Avoid voltage peak / static discharge freezing arduino

texts:
I am building a speed-testing stand for electric wheelchairs with an arduino nano + rotary encoder. The wheelchair is put on cable caddies, which turn the rotary encoders via a belt.

The setup itself with measuring the speed works pretty well.
However, due to the rubber wheels on the metal caddies, charge builds up and then there is a static discharge (you can see the flash), which freezes the arduino.

So far, I don't have any protective circuit for this.
The arduino is connected to power with a USB-Powersupply. The rotary encoders get their power from the VCC+GND Pins of the arduino. The data pins of the encoders are connected to the arduino digital Pins 4 + 5 (defined as INPUT_PULLUP).

What is the best way to protect the circuit from these voltage spikes / static discharges? There isn't really a way to ground the cable caddies, because they are portable and set-up in sport-halls with plastic floor.

Any hints will be greatly appreciated!


texts: Run multiple TECs in series or at multi-channel TEC controller?

texts:
Assume we want to drive multiple thermoelectric coolers (Peltier elements) to control the temperature of a lab setup. To accommodate for the size and shape of the device to be cooled/heated we have to place a total of 12 TECs. They will - driven by the layout - be connected in series as groups of six. Polarity is being taken into account of course. The device will carry only one temperature sensor. Max. voltage per TEC is 0.9 V and controllers with output voltage exceeding 20 V are available, so that this should not be an issue.

The question is now whether it is preferable to use a dual-channel TEC controller to drive each group separately or to connect all twelve in series? Always assuming that the TEC controller can cover the necessary voltage range and total output power.

Side note: I understand that a series connection of all TECs will lead to a failure of the whole system as soon as one TEC breaks. However we assume that a repair would be due in such a case anyways.


texts:
I installed RTX (rtos from Keil) and Ethernet library from STM for stm32f207 MC. I configured UDP using ethernet + LwIP as in examples from STM.

Without RTOS UDP works fine. I send and get packets without any problems, but with RTOS (RTX in my case) i can only send packets with ARP-request but can't get packets due to i have no ethernet interrupts on receiving packets (can't get ETH_DMA_FLAG_R flag). I know, that there are reciving packets because i see them in Wireshark.

So, that's how i configure Ethernet interrupts:

extern ETH_DMADESCTypeDef  DMARxDscrTab[ETH_RXBUFNB], DMATxDscrTab[ETH_TXBUFNB];

/* Ethernet Receive buffers  */
extern uint8_t Rx_Buff[ETH_RXBUFNB][ETH_RX_BUF_SIZE];

/* Ethernet Transmit buffers */
extern uint8_t Tx_Buff[ETH_TXBUFNB][ETH_TX_BUF_SIZE];

...
  ETH_DMATxDescChainInit(DMATxDscrTab, &Tx_Buff[0][0], ETH_TXBUFNB);

  /* Initialize Rx Descriptors list: Chain Mode  */
  ETH_DMARxDescChainInit(DMARxDscrTab, &Rx_Buff[0][0], ETH_RXBUFNB);

  /* Enable Ethernet Rx interrrupt */
    for(i=0; i<ETH_RXBUFNB; i++)
    {
      ETH_DMARxDescReceiveITConfig(&DMARxDscrTab[i], ENABLE);
    }

  for(i=0; i<ETH_TXBUFNB; i++)
  {
    ETH_DMATxDescTransmitITConfig(&DMATxDscrTab[i], ENABLE);
  }

  NVIC_EnableIRQ(ETH_IRQn);

...

void ETH_IRQHandler(void)
{
  /* CANNOT ENTER HERE */
  if (ETH_GetDMAFlagStatus(ETH_DMA_FLAG_R) == SET)
  {
    /* Give the semaphore to wakeup LwIP task */
        sys_sem_signal(&s_xRxSemaphore);
  }

  /* Clear the interrupt flags. */
  /* Clear the Eth DMA Rx IT pending bits */
  ETH_DMAClearITPendingBit(ETH_DMA_IT_R);
  ETH_DMAClearITPendingBit(ETH_DMA_IT_NIS);
}

So, as i said, Wireshark shows me that there are answers with ARP-requests with mac-adress, but i can't enter in interrupt to process them.


texts: charging two 3.6V phone batteries connected in series from a lower voltage source

texts:
This is a circuit I found on the web at http://www.talkingelectronics.com/projects/SolarLight/SolarCharger.html that claims that a 12 volt battery can be charged using a smaller power source.

My power source is 6V DC adapter and I want to charge a 7.2V DC power source (2 3.6V batteries connected in series to make 7.2V)

The site states that I need a specific number of turns for each coil winding.

How would I adapt this circuit to charge 7.2V from a 6V power supply and most importantly, how do I calculate the coil values (looking for inducor values in uH) for optimal charge?

Or should I try a different oscillator design? The website did state this design is an oscillator.

And is there a way to add an LED to the circuit that only turns on to indicate complete charge?

I want to eventually take the charging information into a microcontroller, but for now I want to make the charger work.


texts: How does capacitive EEG electrodes measures EEG signals

texts:
I have read the following sentences from an article:

  The effect that there are also charge displacements on the body
  surface due to brain activity is used for the capacitive measurement
  of the EEG. This change of the charge can in turn affect the charge on
  a metal plate close to the body. Since this electrical plate does not
  require direct electrical contact to the body, it can be isolated from
  the body.

how we could affect the charges of metal plate closed to body without direct contact? does the body acts as the first metal plate of a capacitor?

Is there any specifications to define how much the closeness between electrodes and body?


texts:
I have a GNS FM9 dongle, which is a RDS receiver that came bundled with a sat-nav, intended to be used as a receiver for TMC traffic reports (which are transmitted as part of the RDS data stream).

These devices have a UART interface but come in various flavors—connectors differ depending on the device the dongle came with, and logic level can be either 3.3V or 5V. The chip seems to operate at 3.3V; the correct logic level for the device can be identified by the presence or absence of extra circuitry on the board. The one I have lacks the level-shifting circuitry, suggesting it operates at 3.3V. It has a USB cable, which is plugged in between a USB power supply and the device, although the device-side data pins on the USB cable carry UART signals, not USB signals (which is why the device-side plug does not carry a USB logo). It dies mean, however, that it operates on a 5V power supply.

In order to control it from a PC, I have bought a FTDI232 breakout board. The board has a jumper to select 3.3 or 5V. Looking at the PCB, the middle jumper pin seems to be connected to the Vcc pin on the pin header, though I don’t know for sure what else is governed by the jumper setting. The chip on the board is an FTDI232RL.

What is the correct jumper setting for this device (3.3V logic level, 5V power supply)?

In particular, what are the TX voltage levels at either jumper settings? Do I risk frying the FM9 by setting the jumper to 5V, or is TX voltage guaranteed to not exceed 3.3V with either jumper configuration?

Or do I need to go for a hacky solution, setting the jumper to 3.3V (for the logic level) but taking Vcc from a different source, not the Vcc pin on the 6-pin header?


texts:
Why doesn't the tail resistor feature in the denominator for differential gain (whereas it does for common mode gain) in the differential amplifier below? (Fig 5N.28 from Learning the Art of Electronics)

LAoE explains this by pointing out that in pure differential mode with an equal but opposite difference at each input, the voltage across the tail resistor won't change whereas it does change with a signal common to both inputs. That much is clear but I still don't understand why the tail resistor can be ignored for calcualtion of differential gain.

And what about a differential signal that isn't equal and opposite?


texts: Help identifying a potentiometer/resistor like symbol in the I/O stage of a microcontroller

texts:
I'm having difficulties identifying a schematic symbol. I spotted this while going through the STM32L series reference manual on page 172 located HERE.

Here is the symbol in question, and the symbol as it appears in the document:

It's obvious that it's some sort of electronically switchable resistor, I'm just uncertain what the proper name for it is. I thought it was a Voltage Controlled Resistor however I've generally seen those in schematics as the actual FET, as opposed to a symbol like this. My searches haven't turned up anything.

I know they're the pullups/pulldowns for the port, I just have never seen that symbol before.

Does anyone recognize this symbol or know what the proper name for it is?

Thanks!


texts: Is it possible to measure a meaningful impulse response of a capacitive touchscreen such as the one you might find on a mobile device, with the goal of "calibrating" devices with different touchscreens to one another? What are the most important properties of a touchscreen that determine its "fingerprint", so to speak? Are these properties published in the touchscreen's specification sheet?


texts: How does tuning in a spectrum analyzer actually work?

texts:
I have a pretty basic doubt about how tuning works in spectrum analyzers. I'm reading about the topic from Keysight's AN 150.

The problem arises in this paragraph in page 11:

  We need to pick an LO frequency and an
  IF that will create an analyzer with the
  desired tuning range. Let’s assume that
  we want a tuning range from 0 to 3.6
  GHz. We then need to choose the IF. Let’s
  try a 1-GHz IF. Because this frequency
  is within our desired tuning range, we
  could have an input signal at 1 GHz.
  The output of a mixer also includes the
  original input signals, so an input signal
  at 1 GHz would give us a constant output
  from the mixer at the IF. The 1-GHz signal
  would thus pass through the system and
  give us a constant amplitude response
  on the display regardless of the tuning
  of the LO.

The sentence in bold is what confuses me. As far as I know, the product of two sinusoids of different frequencies returns two sinusoids at the difference and the sum of the original frequencies. So how is it possible that the original input and LO frequencies are present after the mixing?


texts: What's the difference between NPN and PNP transistors?

texts:
This is not a duplicate of this question.

I would like to know what the differences in their characteristics are. I'm thinking for example about their majority carriers (electrons for NPN, holes for PNP). Does that mean that NPNs are faster?


texts: PIC24E writing address and increment for ICSP programming

texts:
I am trying to program my Microchip PIC24EP512GU814 in ICSP mode. The resource I'm using to do this is the Microchip dsPIC33E/PIC24E Flash programming Specifications (70619B) and the Microchip dsPIC33EP/PIC24EP Data Sheet (70616g). So far I've programmed an Arduino to enter ICSP mode, and erase everything on the chip, but I am currently stuck at writing on the chip.

Section 6.6 has a table 6-5 on page 31 which shows steps on how to write onto the chip. Step #6 has the following snippet:

MOV #DestinationAddress<15:0>, W2
MOV #DestinationAddress<23:16>, W3

In context: these instructions are to be executed once 128 instructions have been inputted into the write latches. This snippet define the location in the code memory into which the instructions from the write latches are copied.

I currently can't figure out which address I should start with, and how much does the address increment by for the next 128 instructions?

I've looked at the Section 4.1, Figure 4-1 of the Data Sheet (70616g) and Section 2.3, Figure 2-2 of the Programming Specifications (70619B). Is the code memory the same thing as the User Program Flash Memory in these figures? As such, should the destination address in the above snippet start at 0x000200?

Since this establishes a write for 128 instructions, does it increment by 128 = 0x80? Or does it increment by the number of bits written (24x128= 3072 = 0xC00)?


texts: Why do condors get electrocuted by power lines?

texts:
Plenty has been said about why birds are safe to land on power lines. But condors, apparently, are not. The linked article explains that condors are electrocuted often enough and endangered enough that they are doing special "power pole aversion training" to keep them away even after release.

Why are condors electrocuted while other birds (pigeons, crows, etc.) are perfectly safe?


texts:
this is my buck boost converter in the simulation
i get the desire voltage -12V but in real circuit i just getting -4.88V ,
and my transistor heats up i think it is even burned ,
I dont know how I turn on and turn off my
transistor safley.
why i am getting higher voltage than -12V?
my transistor is silicon pnp.


texts:
Currently learning about ferrite beads.

I have noticed that on the data sheets they have graphs of impeadance vs frequency.

to ensure you have the best ferrite for the job I assume you want to get the greatest impeadance at the frequency you are experiencing the noise.

Can anyone confirm why having a greater impeadance is better?

Thanks
SS


texts: Dual edge triggered D flip flip CMOS implementation. Less than 20 transistor

texts:
I need to implement a dual edge triggered D flip flop (DET) in a CMOS IC using 0.35u technology. The best design which I could fine is this one http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=210012&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel1%2F4%2F5446%2F00210012.pdf%3Farnumber%3D210012

I attached the circuit to this post also.

First question is: As I am using 0.35u then is it enough just to scale the W/L ratio of the given design (it assumes 1u technology) or there must be other consideration put into account? The  designer emphasizes that W and L are important and it will not work if we don't follow the given specs.

Second question: I implemented the design in that paper, but the given circuit just doesn't work right now. Do we have another design, which uses less than 20 transistors and can perform latch on both rising and falling edge of clk?


texts: What is the best way to manually choose between bi-directionally shifting 3.3v signal to 5v and "using" that signal directly?

texts:
I am designing a breakout PCB for a microcontroller which operates at 3.3v and I'd like to add a jumper which specifies if whether the 3.3v signal from multiple GPIO pins will first go through a bi-directional 3.3v <-> 5v IC (when the jumper pins are connected) or not, in order to increase versatility. This functionality will be implemented on 16 GPIO pins.
Also, I prefer each breakout board pin to output the same current as the MCU(20mA typical / 50mA max.) in both 3.3v and 5v modes, when the respective GPIO is set to output via software.
Is there any way to implement this? If yes, then how, and which parts should be used?
Thanks in advance.


texts: I purchased a cheap battery head mounted led lamp containing 24 white led's. It is powered by 3 x AA batteries (1.2v each) in series producing approx 3.6v, It works fine when powered from batteries but I had intended to use it along with others to illuminate a terrarium using a converted computer ATX switched power supply's 3.3v rail. It worked but after a few minutes the molded plastic mirror reflector started to crackle and deform as the printed circuit board the led's are soldered to became very hot. My question is Why do they overheat when using a power supply but not when using batteries and what would I need to do to prevent them from overheating when powered by the ATX supply ? Im sure this is a resistance issue but just can't get my head around this one.     Thanks in advance.


texts: Transfer Function and Bode Plot from Poles and Zeroes

texts:
I've got the following bode plot from a black box:

I've calculated the zero to be 1055 and pole to be 67. Thus I'm using the transfer function \$H(s) = (s-1055)/(s-67)\$ but this gives a clearly wrong bode plot:

WolframAlpha calculation

I'm guessing my transfer function is wrong. Can anyone see how?


texts: Schottky diodes for dissimilar Ah e-bike parallel batteries

texts:
I have purchased an auxiliary 18 Ah lithium battery to supplement the stock 13 Ah battery. For convenience, I would prefer to configure them in parallel for operation. The resulting slower drain should extend battery life. But there will be many situations where the batteries will be separated and become dissimilar in charge. I want to do something to stop or slow excessive reverse current flow that could damage my batteries.

Are Schottky diodes right for the task and can anyone draw me a schematic or share any relevant advice?


texts: Building a triangle wave generator using two LM358 with single supply operation

texts:
I am trying to build a triangle wave generator with the following specifications:

The triangular wave must oscillate between V_max=7.2 V ,V_min=1.6 V
Duty cycle = 0.5 ±1%
Frequency, f_osc= 8.5 kHz ±5%
Supply voltage = 12V (single supply operation)

Does anybody have a formula or guide to build a triangle wave generator with two LM358 op amps?
The circuit I came up with does not give me the desired output:


texts: How do I bypass the ac rectifier in a guitar amp so I can power it directly with DC power source instead of mains?

texts:
I have a guitar amp that died recently, the primary coil of the transformer lacks continuity when tested with a multi-meter. I am trying to power it with a 9V power source instead of AC power outlet. I am intending to bypass the rectifier but I'm not sure where to hook up the 9V source on the circuit board.

The transformer outputs 10.5 volts and I figured 9V should do the trick if I don't pass it through the diodes. The fuse is rated at 1 Amp and the 9V source is also 1 Amp.

I diagrammed out the power source circuit. Hopefully that is enough information. Pretty new to all this stuff. Thanks in advance.

simulate this circuit – Schematic created using CircuitLab

--Update--

Looks like I'm going to need something like this to create a power supply that is split into +9V and -9V with a ground at 0V:

Found this and more here


texts: The equipment I have needs +5V +12V and -12V supplied to it. The old PSU which provided all the voltages blew to bits. I have sourced a PSU1 +5V (30A), and PSU2 &PSU3 (two identical +12V (2A) stand alone supplies). Am I right in thinking if I link the 0V from PSU1 to 0V PSU2 and +12V of PSU3 I will achieve my +5V, +12V and -12V (from the 0V of PSU3)? Or is it not that simple and I can expect a bang?


texts: Is there any way to interface 4x4 matrix keypad using 2 IO lines

texts: I have two IO lines and wants to interface 4x4 matrix keypad. Using MUX ICs I need 4 IO lines. Is there any method to achieve it using 2 IOs?


texts: Way to calculate the dangerousness level of volts+amps? (don't want to learn the hard way)

texts:
Is there a formula to calculate the dangerousness of amps, and volts?
like watts, for example. Watts = Volts x Amps. Generally speaking, you could say wattage takes into account volts, and amps.
I am working on a robot. And am using high power motors. I don't want to learn the hard way, by getting shocked.
I need a formula, or at least a wattage chart, to see, where, on the dangerousness scale my electrical system is.

If I am touching a 1.2ft wire supplying 12v 80A of electricity, how fatal would that be (both heat wise, and shock wise), or would i be able to feel it at all?


texts:
With this drawing I want to simulate the behavior of the following differential amplifier.

I only draw half of the differential amplifier. Because I think they are equivalent.
But when I simulate it, I found that the drain current M1 is not equal to I1. I1 is always
1mA, whereas the drain current of M1 has increased to 81A. How can this happen?

Moreover, how can I calculate the upper bound of common mode input range actually? If the output voltage (drain voltage of M1) is always increasing when I increase V3, then M1 would go to Triode region if I keep increasing V3. It would be very big.
To sum up,
my questions are following:

How can the drain current of M1 differ from I1?
How to calculate the upper bound of V3?
Thanks!


texts:
I'm looking for a SMD optocoupled TRIAC part for driving EL Wire (110VAC, 1000Hz, low current non-resistive load) with an ATTiny85 pin (TTL, 20mA max) running at 3.3V.

The previous design used the Z0103 non-optocoupled TRIAC, but it seems there is a lot of problems related to noise and the AC ground floating in relation to the DC ground. I've searched for some parts on Mouser but all of them have a very low maximun input voltage (~1.5V, and I need 3.3V) or extremely high (> 64V).

Any advice or recommendation is welcome, but please suggest something I can buy from Mouser (the only store that ships to my country). I not totally sure what I'm doing so any correction is welcome too.

Thanks in advance.


texts:
I'm trying to port some example code from the ST standard library examples. Specifically, there is a file called stm32_eval_i2c_tsensor.c that read and write registers for the temperature sensor, and read the temperature.

I do not understand why DMA was used here. The responses from the temperature sensor are at most two bytes long. The most difficult part of the porting is the DMA, and I would much prefer to use "polling" instead.

Is DMA really required here to read the temperature of a temperature sensor?


texts: How to use the UART functionality in this Bluetooth module?

texts:
I'm using a Bluetooth module called SPBTLE-1S whose datasheet is here -
https://www.st.com/resource/en/datasheet/spbtle-1s.pdf

In the datasheet, it says that I can use the UART functionality by setting the 'mode' to 001.
But I've searched everywhere and could not find how to set the 'mode'. I want to know how I can use the UART functionality by setting the 'mode' to 001. How can I do this?

EDIT - Also, I don't seem to find information on how to put it to low power modes. How can I do that too?


texts: High voltage/Mid current boost converter

texts:
I'm designing a regulator/converter that can generate -120/-108/+60Vdc for a current of 180mA each from a supply of 12Vdc or 24Vdc (5A like it's nothing, 15A tops) and I was choosing a MC34063 but the absolute maximum rating for Vout is 40Vdc:

Is it sane to overspec for 300%? In the datasheet there is a circuit for use with external transistors, but I really know little of supply design.
Is there another ubiquitous IC for doing this? (I googled it and all that I can find are car inverters)

EDIT: the three separate rails can be independently regulated

EDIT: for the record there is a circuit called the Villard cascade that works for very low currents (like the CRT screens), but it was too dangerous to prototype (by me).

Final Update
I found a full LED replacement for the screen I was planning to supply and for the old ones we salvaged supplies from older equipment.


texts:
I have to do some (simple) calculations for a transmission line. I was given a power supply of \$11V\$/\$22\Omega\$, \$Z_0 = 50\Omega\$, \$v = 2.2 \times 10^8 m/s\$, a load capacitance of \$1.124nF\$ and the length of the line is \$ l = 22m\$.

I have to calculate the values for \$v_1\$ (voltage at the input of the transmission line) for instants \$t=0.2^-us\$ and \$t=0.2^+us\$. For \$t=0.2^-us\$ it is easy to see that the reflected wave didn't get to the source yet, so we only have a resistance divisor between the internal resistance of the power supply and \$Z_0\$. Easy calculations gives \$v_1 = 7.64V\$ (I did a quick SPICE simulation and it seems to be ok).

For \$t=0.2^+us\$ I thought I could just calculate the reflection coefficient in the load and see what is the reflected component so I can finally calculate the voltage \$v_1\$. But I don't have the frequency of the wave (it wasn't given at least) to calculate the capacitor impedance and them the reflection coefficient and I'm stuck. Do I need to ask more information or is there another way to get to the result?

EDIT: here is the SPICE simulation.

Thanks in advance.


texts:
hello everyone editing my previous post, i have biased my circuit now i want to run it for s-parameters simulation but when i attach term port it is giving a negative S(1,1).. any help would be appreciated.. and when i remove the dc source attached to input for s parameters simulation it gives same biasing issues .. any leads..
i am working on a task of designing an IQ modulator, as i am working on a paper, i have designed the circuit attached below.
but it is giving a negative plot of S21, and few warnings, i am unable to figure out the problem... any leads would be appreciated..


texts:
I am designing PCB and schematic in Altium Designer. I need to add this IC to board design. TI does not provide any libraries and Altium files containing this IC. But in data sheet there's information about footprint:
LGA Package
– 1.27-mm Pitch, 63-Pin, 20.5-mm × 17.5-mm LGA Package for Easy Assembly and Low-Cost PCB Design

Maybe I can generate this footprint somewhere for Altium?


texts: Instrumentation Amplifier required for 24 bit ADC?

texts:
I am trying to build a measurement circuit that is capable of measuring voltage signals in the order of micro volts.

Signal Characteristics:

Voltage: Anywhere between 1 uV to 100 uV

Frequency: Minimum 10 kHz to maximum of 50 kHz.

The signal needs to be converted to the frequency domain. It is very important for me to measure the odd harmonics. I am planning to do this on a PC after ADC processing.

Current Design:

Currently I am using a 24 bit ADC ADS127L01 from Texas Instruments. I have followed all the design recommendations. I am using a reference voltage of 2.5 V and as per the datasheet will be using an ADC driver THS4551 as well.

Question:

Do I need to use an instrumentation amplifier for this design? I do not think it will be very helpful as I am using a 24 bit ADC, but I am worried about losing bit resolution due to noise and layout issues.


texts: Relay if powered with ac supply then turns adjacent circuit on automatically

texts:
I took the idea from the below link to build my own relay board.

http://www.electronics-lab.com/project/toggle-on-off-switch/

I connected 3 of this in parallel with voltage. All seems well until I dont power common of relay. If I give AC power to the common of relay the adjacent circuits turns on automatically. The strangest thing is when I push A's button then circuit B & C are affected randomly

Any guess what could be wrong....


texts: Is a 12V voltage step-up USB to 4-Pin PC adapter safe to use in an enclosed space for extended periods of time?

texts:
I am interested in using an adapter cable such as this to power a 4-Pin fan through usb:

The fan specifications are as follows:

Now, my question is this - Is something like this safe to use for an extended period of time in a mostly enclosed space? I am concerned that it will get hot, maybe overheat, and be dangerous. Assume the build quality of the converter is adequate. I had never heard of one of these until now and just wanted to be safe before making the purchase. Thank you in advance!

P.S. - I know nothing about electrical things so sorry if this is a dumb question or if you need more details to answer. Thanks.


texts: Capacitor commutation of thyristor and DC load

texts:
In my school notes I have been given a basic thyristor circuit. I would like to breadboard a similar circuit and have some questions about choosing a suitable capacitor type and value between points P and Q.

simulate this circuit – Schematic created using CircuitLab

Assuming the thyristor is latched on and S2 is open, the voltage at P will be close to zero and at Q should equal Vs.

When S2 is closed, I am told to expect Q to immediately drop to 0V.

To quote my notes: "However, there has been no time for charge to move. As a result, Q must still be 12 V higher than P. In other words, when the voltage at Q dropped by 12 V from 12 V to 0 V, the capacitor forced the voltage at P down by the same amount, from 0 V to -12 V."

The thyristor is thus reverse biased and switches off; the voltage at P therefore returns to Vs, but if S2 has not been released Q remains at 0 V. When switch S2 is released, both P and Q will be at Vs.

Bearing in mind the reversal of charge on the capacitor, could you suggest a suitable capacitor type to breadboard this circuit? I assume a polarised capacitor (e.g. electrolytic) would NOT be suitable. Also, how would I calculate a suitable capacitor value? I presume that R2 must be at least 1K to minimise current flow when S2 is pressed. I have not been given a formula to use.

I intend to use a 12 V supply and thyristor C106DG.


texts:
I've never encountered anything in this package. Is it a crystal oscillator? What are the six pins used for? Would it potentially be ovenized?
All I know is that the manufacturer is Kyocera. Any help greatly appreciated!
Markings: Kyocera 7M37 012C M1
Logic chips, DIP-8 oscillator, and HC-49/U resonator are included for size reference. The circular things in the middle are the mystery devices of interest. I did not clip off two of the leads - they're all like that.


texts: Mono to stereo circuit only if one cable is plugged in

texts:
Im not sure how to phrase my question or what to google, but does anyone know how this feature is implemented (eg a simple example circuit):
On some audio mixers, if only the left channel is plugged in, the audio from this input will be split across the left and right channels. However if both left and right inputs are connected, then the audio from the left and right inputs will remain separated on the left and right channels.
For example, a behringer q502 mixer has this functionality, it is marked on the mixer as "mono L"

I know this could be implemented by having a separate switch to toggle between stereo and mono inputs, but im curious how this is done by simply plugging in a TRS cable.


texts: How to Reconfigure a Current Sense Amplifier Pspice Model

texts:
I downloaded the .lib Spice library for the MAX4172 and imported it into OrCad, available from:  https://www.maximintegrated.com/en/products/analog/amplifiers/MAX4172.html/tb_tab2

The library file looks right and I compiled it into a .olb file for Cadence. However, when I come to simulate it, I see this error:

**** EXPANSION OF SUBCIRCUIT X_U2 ****

X_U2.R+ +24V X_U2.ib+ 1g
X_U2.R- N371295 X_U2.ib- 1g
X_U2.Vi+ X_U2.ib+ 0 0
X_U2.Vi- X_U2.ib- 0 0
X_U2.Fi+ +24V 0 VALUE

----------------$

ERROR(ORPSIM-16037): The syntax used for F or H devices is incorrect.
The specified syntax is only for E and G devices. Correct the syntax
and save the file before simulating the design again.
+ {-I(Vi+)+27u}

X_U2.Fi- N371295 0 VALUE

-------------------$

ERROR(ORPSIM-16037): The syntax used for F or H devices is incorrect.
The specified syntax is only for E and G devices. Correct the syntax
and save the file before simulating the design again.

I've never seen the error 'Syntax used for F or H devices is incorrect' before, and I can't find any reference to it online. I tried making the change suggested, but that doesn't solve anything. I can only assume there must be an error in how the .lib file has been configured.

Is there a way of modifying the Spice model to solve this error?

I'm using OrCAD Capture ver 17.2-2016, if that helps.

Thanks in advance.


texts: Why build errors when connecting timers in Quartus ii?

texts:
I use the Nios 2 IDE from Altera with the Altera DE2. I add a file Functions.c with code that needs a timer e.g.

int main ()
{
  int w[8192];

  int a, b;
  int size = M;

  printf("Working Set\n\n");
  printf("Information about the system:\n");
  printf("\n");
  printf("Processor Type: %s\n", NIOS2_CPU_IMPLEMENTATION);
  printf("Size Instruction Cache: %d\n", NIOS2_ICACHE_SIZE);
  printf("Line Size Instruction Cache: %d\n", NIOS2_ICACHE_LINE_SIZE);
  printf("Size Data Cache: %d\n", NIOS2_DCACHE_SIZE);
  printf("Line Size Data Cache: %d\n\n\n", NIOS2_DCACHE_LINE_SIZE);

  /* Check if timer available */
  if (alt_timestamp_start() < 0)
    printf("No timestamp device available!");
  else
    {

      /* Print Information about the system */
      printf("Information about the system:\n");
      printf("\n");

      /* Print frequency and period */
      printf("Timestamp frequency: %3.1f MHz\n", (float)alt_timestamp_freq()/1000000.0);
      printf("Timestamp period:    %f ms\n\n", 1000.0/(float)alt_timestamp_freq());

      /* Calculate Timer Overhead */
      // Average of 10 measurements */
      int i;
      timer_overhead = 0;
      for (i = 0; i < 10; i++) {
        start_measurement();
        stop_measurement();
        timer_overhead = timer_overhead + time_2 - time_1;
      }
      timer_overhead = timer_overhead / 10;

      printf("Timer overhead in ticks: %d\n", (int) timer_overhead);
      printf("Timer overhead in ms:    %f\n",
         1000.0 * (float)timer_overhead/(float)alt_timestamp_freq());

    // === Task 1 : Block Sizes ===

    // Function 1.1
    initArray(w, 8192);
    printf("Function 1.1: ");
    start_measurement();
    for (i = 0; i < 128; i++)
       w[i]++;
    stop_measurement();
    printf("%5.2f us", (float) microseconds(ticks - timer_overhead));
    printf("(%d ticks)\n", (int) (ticks - timer_overhead));

      printf("Done!\n");

  }
  return 0;
}

But I get build errors when trying with different timers in the system properties time. Can you tell me how I should connect the timers?

I suppose that I should not build with no system timer and adding the file requires a timer. When I add the file I get these errors.

make -s all includes
Compiling Functions.c...
../Functions.c: In function `microseconds':
../Functions.c:20: warning: implicit declaration of function `alt_timestamp_freq'
../Functions.c: In function `start_measurement':
../Functions.c:35: warning: implicit declaration of function `alt_dcache_flush_all'
../Functions.c:36: warning: implicit declaration of function `alt_icache_flush_all'
../Functions.c:38: warning: implicit declaration of function `alt_timestamp_start'
../Functions.c:39: warning: implicit declaration of function `alt_timestamp'
../Functions.c: In function `main':
../Functions.c:58: error: `NIOS2_CPU_IMPLEMENTATION' undeclared (first use in this function)
../Functions.c:58: error: (Each undeclared identifier is reported only once
../Functions.c:58: error: for each function it appears in.)
../Functions.c:59: error: `NIOS2_ICACHE_SIZE' undeclared (first use in this function)
../Functions.c:60: error: `NIOS2_ICACHE_LINE_SIZE' undeclared (first use in this function)
../Functions.c:61: error: `NIOS2_DCACHE_SIZE' undeclared (first use in this function)
../Functions.c:62: error: `NIOS2_DCACHE_LINE_SIZE' undeclared (first use in this function)
../Functions.c:52: warning: unused variable `a'
../Functions.c:52: warning: unused variable `b'
../Functions.c:53: warning: unused variable `size'
make: *** [obj/Functions.o] Error 1
Build completed in 2.3 seconds


texts:
This is my first time to get a gerber output from a .brd.

I've followed this way: Cam Processor -> Load JobFile -> Local Cam Jobs -> Examples -> Legacy -> gerb274x.cam

I've encountered two warnings here:

I've fixed first warning with taking the files that stand on legacy part to gerber part with the recovery icon next to them. Can be seen in pic.

Fixed second warning as program adviced, generate excellon outputs based on pcb stackup.

after all, processed the job and I get:  .sts  .stc  .sol  .pls  .plc  .drl  .cmp  .xln  .gbrjob 9 files in total.

my question is am I doing right all the process?

Because when I select "two layer deafult" in templates, I got no warnings what's the difference between them?

If you have another advice to export gerber files I can gladly follow.


texts: How do I calculate the collector current of this circuit with a bipolar junction transistor?

texts: I need to calculate the collector current of this circuit, but I don't know how to approach it. I think the circuit is in the active zone but since my teacher isn't responding to my emails I'm not sure.


texts: program/debug via the built-in usb in efm32

texts: how program/debug silabs EFM32 via the USB built-in interface? is it possible to do that with a simple USB cable without any adapter?


texts: Class AB or Class D for a home theater amplifier

texts:
I am planing to assemble a 5.1 channel amplifier. I selected the famous TDA2030 as the basic element and is simple to proceed. But I have a confusion, whether to use some other Class D amplifier for better quality.

Please share your experience about these classes of amplifiers in the term of their output quality. I really don't care about the efficiency or the size.


texts: Can someone explain a couple of lines of Verilog to me?

texts:
I'm a student trying to learn Verilog on my own with a dev board. This is just a simple and short module. I just need some clarifications.

module BASIC (CLOCK_50, KEY, LEDG);

input CLOCK_50;
input [3:0] KEY;
output reg [8:0] LEDG;

reg [2:0] key0_dly;

always @(posedge CLOCK_50)
begin
  if (!key0_dly[2] && key0_dly[1])
    LEDG[0] <= ~LEDG[0];
    key0_dly <= {key0_dly[1:0], KEY[0]};
end
endmodule

now I know the basic syntax of Verilog. My questions would be:

What is the purpose of key0_dly? Why does the if statement check the 2 bits of it?
Why is key0_dly assigned the values {key0_dly[1:0], KEY[0]}? What does that line do?
Is this line key0_dly <= {key0_dly[1:0], KEY[0]}; in the if statement? Am I correct in saying that if there is no begin and end then like in C only the one line of code that follows in the if block?


texts:
simulate this circuit – Schematic created using CircuitLab

I am having difficulties in simplifying and finding the equivalent for the circuit shown. Can someone guide me to the appropriate start of how to simplify the problem?


texts:
I've used analog and digital input for a multitude of applications with the Arduino Uno board. It has continuously given extremely non reliable readings, where the analog input is always fluctuating, or digital read will read true even if it isn't connected to anything. Is there a way when connecting to a digital or analog input pin that will eliminate that problem? Like a capacitor? I'm not very well versed in electronics, I understand basics on transistors, diodes, resistors, etc... But I don't know much about eliminating electrical signal noise. I feel that with so many false positives my ability to create more complex projects is completely shot.

Any suggestions on eliminating all the extra false positives/noise when receiving Analog/Digital Input on an Arduino Uno?


texts: Creating a component library which includes distinct elements

texts:
I'm learning custom library design in Altium Designer. I designed several libraries so far (BJTs, resistors, capacitors, etc), all worked without any problem. This time I tried to design an IC package (TL082 Opamp) which contains two distinct circuit elements in it.

The PCB and schematic libraries look like:

The problem is, when I try to use this library in circuit (schematics), the two Opamps behave like a solid one-piece object. I can't move each Opamp separately. Their relative position to each other doesn't change. When I drag one, the other one comes with it. I want to use one of the Opamps in a place far away from its brother, but they just don't want to leave each other.

Native libraries of Altium Designer don't do this behavior. For example, TL084 has four opamps in it, they all can be used independent from each other.
I don't want to use native TL082 library of Altium Designer in my circuit. My aim is learning to design libraries in Altium Designer.

The opamps look like this in the circuit:

How do I separate these two Opamps from each other, so that I can use them independently in the schematic?


texts: GPS 1 PPS Aligment Clock Signal Generator

texts: i want to do GPS 1 pps aligment clock signal generator. Clock signal should be at 24.576 Mhz and voltage level Vmax= 3.3 V and Vmin=0 V DC. How can i do that? It is very important to align between GPS PPS and Clock signal. While looking these components on the internet, i have found MAX24188 and DS31400. I am not familiar with these components. Is it possible to make this with Max24188 and DS31400? If yes can anyone explain me basicly how?


texts: MSP430F6736A UART configuration via Code Composer

texts:
Using embedded proggraming, Code Composer Studio 6.0.1,

Trying to configurate UART to communicate between MSP430F6736A and my PC. Using USB/RS485 converver(2 vire (A,B)).

For sending data using HERCULES(app for testing communication).

         #include <msp430.h>
            #include <msp430f6736.h>
            /*
             * main.c
             */

            int main(void) {

                WDTCTL = WDTPW | WDTHOLD;   // Stop watchdog timer

                P4DIR |= BIT6;
                        P4OUT &= ~BIT6;
                    //clock
                //UCSCTL0 |= DCO_0 | MOD_0;
                //UCSCTL1 |= DCORSEL_0;

                // Config pinov  P2.2 a P2.3 na ich funkciu(Rx a Tx)
                P2SEL |= BIT2 + BIT3; // RX and TX pins

                // config comm
                UCA1CTLW0 |= UCSWRST; // reset UCA1 for config
                UCA1CTLW0 |= UCSSEL_1 ; //  ACLK as source clock
                UCA1MCTLW |= UCBRS0;

                // Baudrate from datasheet
                UCA1BR0 = 1;    // 1200 Baud
                UCA1BR1 = 11;   // 1200 Baud

                UCA1CTLW0 &= ~UCSWRST; // UCA1 back from  reset

                // interrupts enabled for RT and TX
                UCA1IE |= UCTXIE | UCTXIE;

                __bis_SR_register(GIE); // global interupt enabled

            }

#pragma vector=USCI_A1_VECTOR
__interrupt void    Recieve_ISR(void)
{
    while  (!UCA1IFG)    //  USCI_A0 TX  buffer  ready?
    {
    P4DIR |= BIT6;
    P4OUT &= ~BIT6;
    UCA1RXBUF  =  UCA1TXBUF;    //  TX  -&amp;gt;   RXed    character
    }
}

All I want is when I send data(for eample number 5) from HERCULES(config same: 1200 baud, no parity, 1 stop bit) I want to receive them and turn LED on. But it doesn´t work.

Somewhere in this code is something missing or something bad written. , . I got big head from datasheets so can anyone help me?


texts: Proximity sensor suggestion for outdoor human detection with Teensy 3.2

texts:
I'm seeking your advice to find a sensor to use with a Teensy 3.2 for outdoor human detection.

What I'm trying to do

I have multiple micro-controller (a few Teensy 3.2) communicating together with radio frequency. I'd want to have a master device send requests to the slaves when it detects someone in a specific range of the device (1-3 meters away). The microcontrollers are enclosed in waterproof casing and are outside all year long except for winter season.

As the sensor location is static and it does not use a battery, the sensor does not have any special requirements in terms of power consumption or portability but weather resistance and waterproofing is key.

Intended use of the device

It's an outdoor installation with multiple speakers used to create a polyphonic environment.

There are two devices in the installation :

A single master device (with the sensor)
Multiple slaves (controlling speakers)

The idea is that there is a master device that detect someone standing still at a specific range (lets say 1.5 meters away). When it does detect someone, it sends a request to all the slaves (speakers) via RF to play a specific wav file.

Desired sensor requirement

I'd want the sensor to be able to do the following :

Detect someone outdoor in a range of 1 to 3 meters ;
Output a variable distance : I don't want it to be a motion sensor ;
Be waterproof ;
A ready to use (ready to interface) product as my current workplace facilities does not have the resources or expertise to build and engineer a waterproof and weather resistant sensor from scratch.

The current setup

Here's a list of everything I'd want this sensor to work with :

A Teensy 3.2
A Teensy 3.1 XBee Adapter
A Xbee2 S2C RF Tranceiver

Sensor I've already tried

I've already done some test with a MaxBotix 7363 (which is an ultrasonic sensor) with mixed results, the reading being super noisy even with a power filter.

--

Feel free to ask me for more details. Thank you for your help!


texts: Modifications to Neon Sign Transformer to turn it into a variable DC power supply?

texts:
I would like to turn a neon sign transform into a DC power supply.

Looking into this it would appear I need some rectifiers to turn the AC output into DC.
I could use a variable resistor to adjust voltage.
I am unsure how to adjust current. Is there such a thing as a variable adjusting circuit that bleeds off current to the neutral line?

Or is there an easier inexpensive way to make my own DC power supply capable of 4kV and 30mA?


texts: How to connect a stepper motor with exactly 4 wires to Arduino?

texts:
simulate this circuit – Schematic created using CircuitLab

Today I bought a stepper motor to play with, after 12 hours of struggling with it, I haven't been able to figure out how to connect it to an Arduino.

Is it okay if my stepper motor has exactly 4 wires?

Wires are colored: white, blue, red, yellow. All the pictures and circuits of easy tutorials I found on Google had 5 wires, (and those with 4 wires had different color coding anyway). But a 4-wire doesn't make sense! there must be 2 or 4 poles in a motor, and each pole needs a connection to common ground, so there must be 5 wires, how does a 4 wire work?

I'm using MOSFET for driving the stepper, not LMxxx

Because I forgot to buy one, and I can't get my hands on one for a couple of days. I use the MOSFETs as fast switches: 4 Arduino pins control 4 MOSFET transistors. And this is exactly the source of confusion: On arduino website, the sample circuit's stepper has 4 wires and is directly connected to a driver IC (a LMxxx), and the driver is connected to Arduino. Since I do not have a driver at hand, I need to convert the circuit so it works with 4 transistors instead. But what the wiring should be? If it had 5 wires I would have done it like this schematics.

It is very likely there are problems with my PNP/NPN Mosfet choice, but as soon as I know how to wire the circuit, I'll choose the right one!


texts: Determine connections of a transformer based on resistance

texts:
I have a small transformer I desoldered from a disposable camera that transformed 1.5V to high voltage >90V. It has three leads on one side and two on the other. I have been testing its resistance and got the following measurements (*There is an error the resistance from connection 4 : 2 is 270 ohms not 3 ohms)
The 3rd lead seems to be connected to the smaller coil but there is glue and I cannot figure out the other connections. Sorry for the really terrible solder joints (working on it).


texts: Spartan II XC2S50 TQG144 ASM 13 - decoupling capacitor values

texts:
I have a damaged board out of a CCD camera that requires replacement of the Spartan II FPGA chip (XC2S50 TQG144 ASM 13) and a few decoupling ceramic caps around its periphery. There is no schematic or BOM available for the board.

The caps are 1608 (measured with callipers) but the Spartan datasheet makes no specific mention of values. I'm guessing, around 0.1uf but I am not sure how critical the application is. It's low voltage. 1.5 - 3.3v according to the data sheet.

How critical are the cap values?


texts:
I purchased a 5 volt power supply off Amazon. It runs from 120 VAC and produces DC power. It's a switch mode power supply. If I put a multimeter on the output it always shows approximately 5.0 VDC.

I ran into extreme difficultly in using this power supply for any sort of actual project. The output is extremely noisy.

I connected some small capacitors with a value of 10 pF and 10000 pF to the output of the power supply. I would think the power supply would have small capacitors of this type in any case, but apparently not. These eliminate lots of HF noise that is coming out of the power supply. Unfortunately this noise is not really the issue.

Here is what the power supply looks like on my oscilloscope with no load.

Adjusting the time scale and voltage scale I saw this

The channel in blue is the output of the power supply. The channel in yellow is the output of a filter network I built. I used the low voltage side of a mains transformer and a large electrolytic capacitor. Here are pictures of those, although I doubt it matters at all. The inductor is wired in series with my load(if any), and the capacitor is parallel with the power supply.

I decided to test just the power supply with a resistive load. I selected a 10 ohm resistor. This should provide a load of approximately 500 milliamperes.

The filter network deals with some of the oscillations, but there is still an almost 1 volt spike on the output of the filter network. I tried moving the capacitor around, but it makes little difference. In fact, even with the capacitor disconnected the output does not change much.

Here is a small transformer removed from a switching power supply. I connected the 5 volts in series with the primary of this transformer.

And the view from my oscilloscope:

It seems that almost any inductor filters out the oscillation with the period of approximately 3.5 microseconds. But that huge spike the precedes the oscillation remains. In this case the power supply jumps around by over 2 volts. 2 volts on a power supply meant for 5 volts is 40%.

The interesting thing about this is the capacitor seems to make no difference. It is old, but I've tried several and gotten the same result. They all have some capacitance, although it may be slightly diminished over time.

Given the fact the voltage still swings all over the place with the capacitor, my only theory is that the circuit inside the power supply is actually shorting its own output. If the regulator on the output of the power supply just turned off, the voltage would just taper downwards because the capacitor would slowly discharge. It's almost as if the power supply is internally shorting for a brief period of time, then the regulator goes a little nuts and "rings" as it tries to find 5 volts again.

Why is the regulation of my 5 volt power supply so poor and how to address it?

Although I cannot imagine it would help, here is a picture of the power supply with its case off

Update:

I performed an additional test with the mains transformer as a filter wired in series with 4 resistors. One of the resistors was the 10 ohm resistor, the other three were 6 ohm. This should give a resistance of 1.66 ohms for approximately 3.125 amps of current. This does not change anything significantly in the observed output. I reversed my probes in this test, so the colors in this screenshot are reversed as well.

Here is a closeup shot of the "spike" as I called it.

I also tried connecting a 1 microfarad capacitor across the power supply while it was driving the 10 ohm load. Here is what that looked like


texts:
I am somewhat confused on how the current limiter configuration works with the LM317. It's configuration looks as so:

Datasheet: http://www.ti.com/lit/ds/snvs774l/snvs774l.pdf

The formula given is \$I_{out} = \frac{V_{red}}{R1}\$, and the constraints work, because 0.8 Ohms is roughly the minimum load requirement, and 120 is the upper limit of what it can supply (~1.5A)

My issue now, I wish for it to be controlled by a microcontroller via an optical encoder.

A digital potentiometer at least from what I have seen can only pass ~40mA current through it, so that is out of the question
I wish for a very dynamic range, so transistors switching power resistors by uC is not very allowing.

The only thing left I can think about is driving the ADJ pin with the uC, and try to figure out what on earth R1 does to it.

I assume the wire going to ADJ is just to create a path, and Vref (1.25) is otuput in Vout? and V/R1=I passing to Iout. I am not sure how that helps me, as I am left with only 1.25V.

What happens in this schematic? What can I feed ADJ in place of R1, assuming I have a sense resistor that knows the current going through the circuit?


texts:
Background
I am designing a low noise gain section for a power amplifier. This section consists of 2 parts:

the input section, taking care of gain
a single-ended to balanced buffer with unity gain (doubling with added inverter)

After extensive simulation and tweaking I managed to get to very low simulated noise output figures of -115,1dBu (20-20kHz) for the input/gain section and -117.6dBu for the differential converter/buffer.
Known facts

I am aware that noise in opamp configurations can sometimes have a larger than signal gain (but I can't see how this is related to this problem, nevertheless I like to mention it).
I am aware that noise can be added with the rule: Total noise = SQRT(N1^2 + N2^2)
I am aware that the above rule is only valid if noise sources are uncorrelated (as in originated from different parts for example).

Assumptions and question

As far as I see it, input gain section and balanced buffer stage are uncorrelated.
The balanced buffer stage doubles voltage. So if I tie this to the output of the buffer stage, i should be able to add noise by adding twice the input/gain stage noise plus the balanced buffer stage.

If I do this, here are the figures:

gain stage simulated noise output is 1.37µVRMS (-115dBu)
balanced buffer stage (differential) simulated noise output is 1.02µVRMS (-117.6 dBu)
adding these as described leads to SQRT((2*1.37µV)^2 + 1.02µV^2) = 2.92 µVRMS (-108.5 dBu)

If I simulate both sections cascaded, however, I get a different noise output (20-20kHz integrated) of 3.16µVRMS or -107.8dBu.  That's  a 0.7dB difference.
Am I making some wrong assumptions, should i check some overlooked details or is this an effect of other effects that I don't understand or know about? I basically want to understand why the cascaded simulated result is different from the calculated result.
Edit
first stage circuit:

second stage circuit:


texts: How exactly do all FPGAs work together on this board to carry out high speed calculations

texts:
The board I am referring to is called "Merrick 3" from "Enterpoint (ltd)". The web page can be found here: http://enterpoint.co.uk/products/asic-development-high-performance-computing/merrick-3/

I can see that it uses PCIe and has a lot of FPGAs on the board itself. All these FPGAs work together to carry out calculations at very high speed. What is not clear to me is, how is the data coming into such a board structured? Does the main device on the board have somesort of state machine that helps it analyze incoming data and figure out what type of calculation needs to be done with the data?

The other thing not clear to me is how exactly does the board make so many FPGAs work together to achieve result of calculation? Can a Graphics card be made this way?


texts: op amp - current source - voltage output

texts:
I have the electronic schematic bellow composed with two op amp and I want to determine the voltage output of the X2 op Amp.

I m a little bit confusing about the aim of using the zener diode D1 in such circuit. So could any one help me to understand how to determine the Voltage output Vout of the op amp X2 ?
Thanks for your help.


texts: Is it possible to model a PIN InGasAS photodiode in a SPICE simulator?

texts:
I want to know if it is possible to model a InGasAs panchromatic PIN photodiode, in accord with datasheet, in simulator SPICE MicroCAP 12. Because the supplier doesn't provide a SPICE model. And if it is possible, which are those steps.
Here is data-sheet https://www.tme.eu/en/details/ig17x1000s4i/photodiodes/laser-components/ And below I will attach an electrical schematic of a transimpedance amplifier with phototdiode, used as a smoke receiver.
I want to monitor graphically the impulse of photodiode in function of output of transimpedance for sensibilty. I found a type of photodiode in the Micro-CAP 12 library but it is simple photodiode, which does not match the datasheet.


texts:
I know it's the conductive connection between different points on a circuit board, but what is its form, how is it made?

My confusion stems partly from this image of a PCB cross-section, which I encountered when I started reading about how PCBs are manufactured:

This image suggests that there's a continuous layer, a sheet of copper on a circuit board that spans the whole surface. If that's true, how is a trace formed? What breaks that sheet of copper into separate wire-like lines that are isolated from one another?


texts: YM2612 Circuit Audio Signal Offset Voltage

texts:
I've been working on a project messing around with the YM2612 soundchip and hooking it up to a microcontroller.  I'm able to drive the chip, but I'm having a little trouble with the audio part of the circuit.

I have a 10kΩ  pulldown resistor on one of the outputs of the chip (I'm only testing this output for the time being). I've noticed that there appears to be some kind of voltage offset at the output of the chip. I'm still learning about electronics, so I'm not fully sure how to look this up, other than what I think is messing with the "voltage bias", but in most cases, it seems to be about raising the signal's offset instead of lowering it. The signal seems to be the normal audio signal, but instead of being based around 0v as the center, it's about 2.8ish volts or so.

I was trying to amplify the signal since it's a very low audio signal, but with the voltage offset, I feel like using an op-amp just to amplify the signal, with it always being at ~2.8v I won't be getting as much gain as I'd like to (using a 5v supply for this). I'm sorry if some of my terminology is mixed up. I'm happy to elaborate on anything I might have forgotten, but would really love any help or advice you can provide on how to handle the audio output circuit. Oh, btw, I don't want to directly hook this up to a speaker or anything, this is just about obtaining line level for headphones or something of that nature.


texts:
I have recently bought a L9110s H bridge (pictured below), and while testing I accidentally burned it up. I'd like to know why, to avoid making the same mistake and if maybe I should try to get a refund.

Datasheet:
+=========+====================+=======+===========+=======+=========+
| Symbol  |     Parameters     |       |   Range   |       |  Units  |
+=========+====================+=======+===========+=======+=========+
|         |                    |  Min  |  Typical  |  Max  |         |
+---------+--------------------+-------+-----------+-------+---------+
| VCC     | Supply Voltage     | 2.5   | 6         | 12    | V       |
+---------+--------------------+-------+-----------+-------+---------+
| Idd     | Quiescent Current  | -     | 0         | 2     | uA      |
+---------+--------------------+-------+-----------+-------+---------+
| Iin     | Operating current  | 200   | 350       | 500   | uA      |
+---------+--------------------+-------+-----------+-------+---------+
| IC      | Continuous         | 750   | 800       | 850   | mA      |
+---------+--------------------+-------+-----------+-------+---------+
| IMax    | Current peak       | -     | 1500      | 2000  | mA      |
+---------+--------------------+-------+-----------+-------+---------+

My setup:

Motors: Generic motors from an old RC car. I can't see any number on them so I don't have much info. They came with a 100nF ceramic capacitor soldered on both ends. I have tried to connect them manually to the 5V and GND terminals of the power supply, and they worked just fine did not show any problems.
Power: ATX PC Power Supply (5A/3A current), with VCC connected to the 5V entry.
Situation: I connected the VCC and GND to a breadboard with 5V and GND from the power supply. When I connected A-IB to the 5V (to power a motor up), I heard a crackling noise, the two transistors started heating and emitting magic smoke, and they got so hot they actually fell from the chip. I screwed up real bad.

Schematic:

simulate this circuit – Schematic created using CircuitLab

There are two things I'd like to know:

What was my mistake and
Was my L9110s bridge defectuous? I know it was probably my fault, but I think it's weird that the soldering was so weak the transistors fell out when it overheat.


texts: Msp430 Launchpad Using Motor to Control Motor

texts:
I can blink the led but the time of it's very 1 second or 2 second.I try to increase but it did not.But my question I'm using L293D motor driver to control motors.I want to Dc motors turn when button switched 15 second.This my code but I can't find a solution.I m asking how to increase the time

#include "io430.h"
void delay(unsigned long int d)
{
  d*=9999999999999999;
  for(;d>0;d--);
}
void main(void)
{

  WDTCTL = WDTPW + WDTHOLD;             // Stop watchdog timer

P1DIR = BIT6 + BIT4  + BIT7 + BIT0;          // Toggle P1.0 using exclusive-OR
P1DIR &= ~BIT3;
if((P1IN&BIT3) == 0){
P1OUT |= BIT6 + BIT4  + BIT7;
}
else
{
 P1OUT |= BIT0;
delay(9000);
}
}


texts:
I'm designing an equipment that will be in a rural area exposed to heavy rains. I already got an IP67 rated enclosure with IP67 connectors and it's working as expected.

I need to measure the ambient pressure so I found this sensor for the task. The issue is, I need to drill a hole for the pressure inside the enclosure be the same as the pressure outside. But this hole will be an entrance for water during heavy rains. I found this image from a mesh used in the iPhone 7 that allows air to pass through but not water:

But I couldn't find the name of this meshes or something similar. I'm thinking that I could protect the hole with a mesh like that to prevent water entrance.

Does this meshes has any special name? What other approach is used to measure ambient pressure in this conditions?


texts:
I am trying to interface a MCU to an external non-volatile memory. The MCU being considered is TM4C123GH6. The memory selected is an SD card which is interfaced via SPI.

But the environment is a high vibration one which may cause the card to be dislodged. The other option could be eMMC. But are there MCUs with eMMC interfaces ? Any suggestions ?


texts:
I have seen several similar questions on the internet but I can't find a straight answer.
I have a ton of used single strand 16 gauge wire that I would like to use. I know that 16 gauge wire typically is suitable for 10 amp. If I double or triple the wire, can I use it on a standard 15 amp outlet?


texts:
I have two PCs (very old, without usb but rs232 port) that talks via RS232. They send to each other very small bit of info ( one character every 10sec). Now I need to connect additionally two sensors that send data to first PC. I assume no collision for all devices. I have tried to make all devices TTL lvl using MAX232 and it works only for two devices sending data to PC1 (e.g. PC2 and sensor1). When I connect sencond sensor (like on schematic) then there is no communication at all. I guess the MAX232 input in PC1 goes overload for 3 devices. Question - Do you know how to make it right for 3 devices? Maybe tying up Tx pins of both sensors on RS232 lvl and then put it to one MAx232? Any solutions with no use Rs485? (I have no handshakes..)

EDIT: Here is schematic that would do the trick. Reply provided by Wouter van Ooijen.


texts:
I am looking for feed back on the following power supply design.

This power supply is intended to have 2 outputs: 24V @ 500mA and 32V @ 850mA.
When the power supply is in standby, J1 pin 1 is @ 0V, the outputs change to 7.48V and 9.75V respectively. When the power supply is active J1 pin 1 is @ 3V.

Is my feedback to the LT1370HVCT7 going to work with my mosfet
switches?
What kind of power requirements am I going to need for
the 12V input?  I haven't been able to figure this out.
What, if anything, am I missing?

Higher Res Schematic

UPDATE:

Changed input voltage to 5V
Tried to follow theamk's advice and use series R2 resistors for the voltage divider so I could short out one of one of them thus changing the voltage divider output
Using a p-channel mosfet to drive the 2 n-channel mosfets
Added logic level shifter 3V to 5V for the standby input

Higher Res Schematic

How is it looking now?

UPDATE 2:

Used gsills standby divider switch
Removed level translation

Higher Res Schematic


texts: always_ff is always executed earlier than always_comb in ModelSim

texts:
I have an exercise that separating comb logic from sequential logic in always_ff block.

However, I found that the ordering of always_comb and always_ff executions is different between different simulators.

As far as I know, always_comb block is executed whenever the variable in sensitivity list changed. (Please correct me if I am wrong) and always_ff is executed at signal edge (e.g. clk).

From the programming prospective, the execution ordering of always_comb and always_ff is important, right? We always assign a variable in non-blocking way inside flip flop from a variable which is driven by always_comb?

out_pkt_size <= pkt_size; // pkt_size is drive by always_comb

Please advise.

You can checkout the code from edaplayground

always_comb begin
    $display("%2g, always_comb       : in_vld       = %b", $time, in_vld);
    if (in_vld) begin
        pkt[HIBIT-:WIDTH] = in_data;
        pkt_size = {<<8{pkt[HIBIT-:16]}};
    end else begin
        pkt = {WIDTH{1'hx}};
        pkt_size = 'd0;
    end
end

always_ff @(posedge clk or negedge reset_n) begin
    $strobe( "%2g, always_ff(strobe) : out_pkt_size = %1d", $time, out_pkt_size);
    $display("%2g, always_ff         : in_vld       = %b", $time, in_vld);
    if (!reset_n) begin
        out_pkt_size <= 1'd0;
    end else begin
        out_pkt_size <= pkt_size;
    end
end

Run result from edaplayground (using Synopsys VCS as simulator):

You can see that always_comb is executed earlier than the always_ff.

initial ...
 0, always_ff         : in_vld       = x
 0, always_comb       : in_vld       = x
 0, always_ff(strobe) : out_pkt_size = 0
10, always_comb       : in_vld       = 0
10, always_ff         : in_vld       = 0
10, always_ff(strobe) : out_pkt_size = 0
20, always_comb       : in_vld       = 1
20, always_ff         : in_vld       = 1
20, always_ff(strobe) : out_pkt_size = 140
30, always_comb       : in_vld       = 0
30, always_ff         : in_vld       = 0
30, always_ff(strobe) : out_pkt_size = 0
40, always_ff         : in_vld       = 0
40, always_ff(strobe) : out_pkt_size = 0
50, always_ff         : in_vld       = 0
50, always_ff(strobe) : out_pkt_size = 0
$finish called from file "testbench.sv", line 96.
$finish at simulation time                   55

Result from ModelSim:

You can see that, however, the always_ff is always executed earlier than the always_comb. It results the out_pkt_size is 1 clock cycle behind.

run
# initial ...
#  0, always_comb       : in_vld       = x
#  0, always_ff         : in_vld       = x
#  0, always_ff(strobe) : out_pkt_size = 0
# 10, always_ff         : in_vld       = 0
# 10, always_comb       : in_vld       = 0
# 10, always_ff(strobe) : out_pkt_size = 0
# 20, always_ff         : in_vld       = 1
# 20, always_comb       : in_vld       = 1
# 20, always_ff(strobe) : out_pkt_size = 0
# 30, always_ff         : in_vld       = 0
# 30, always_comb       : in_vld       = 0
# 30, always_ff(strobe) : out_pkt_size = 140
# 40, always_ff         : in_vld       = 0
# 40, always_ff(strobe) : out_pkt_size = 0
# 50, always_ff         : in_vld       = 0

run


texts: The optimal way of MCU power consumption measurement

texts:
I'm trying to measure the power consumption of various MCUs(AVRs and STM32). For this measurement, a power supply and oscilloscope will be used. Because I want to plot the power usage vs time just like the following link, it is not possible to use multimeter and pwoermeter. They have bad time resolution and also delay. Thus power supply, oscilloscope and some ammeter will be used.

But in order to get nice accuracy, time resolution, I'd like to ask what kind of way is the best.

First, shunt ammeter seems not to be recommended, because the expected current draw on MCU would be 0~200mA. The way would show large error.

But I don't know which one is better between feedback ammeter and current probe. For time resolution I need 1~10ms and the currents will be in range of 0~100mA. But I have no idea which one would be better.

Any help will be appreciated.


texts:
I've built an amplifier with an lm386 but when I connect a speaker (8ohm) to the output I get a very distorted signal. The problem appears only when the speaker is connected. If I connect an external amplifier to the lm386 output, the audio is right.
The issue appears also without gain capacitor between pin 1 and 8 and with the most basic configuration from the datasheet (LM386 with Gain = 20, page 8 on TI datasheet)

How is it possible?


texts: How do the VLSI design rules for finFET differ from traditional MOSFET/CMOS design?

texts:
I'm taking an intro to VLSI class right now and we're learning the design rules for laying out chips on a 600 nm process. This was the state of the art in the early 90's so it should be a little out of date. From what I can tell, most modern processes use finFETs right now. I know the design rules we're learning are scalable to some degree, but can they apply to finFETs as well? For instance, if I want to build a gate, can I make the same metal/silicon/poly drawings that I did for CMOS, despite the new type of transistor?

I guess I'm just asking what design considerations are different when working with finFETs vs older technologies. None of the sources I can find about finFETs also talk about how they are actually designed or manufactured in a modern chip. Thanks for your help!


texts: How to keep/save minimum Vds value of a FET in Analog Design?

texts:
For a specific application, I need to determine minimum Vds(in other form min Rds) and need to apply it to inverting input of an opamp. I have a source comes with huge ripple like below:

Before anyone suggest it, no, I can not simply measure the Vds on steady state and put a needed resistor for measured Rds. Because, supply voltage also varies between 13 and 11V and so ripple. Besides, output impedance also varies. So I need to develop an analog design to first, determine the minimum Vds then try to keep that potential on the opamp's inverting gate.

You can see the concept in the schematic below:

simulate this circuit – Schematic created using CircuitLab

All the components in the circuit must be analog so please avoid to suggest digitally controlling the voltage.


texts: Is CAT5 cable good enough for RS-485 vs "true" RS-485 cable

texts:
I have a serial comms project coming up.  A number of boards with RS-485 interfaces need to communicate.  Date rate is 57600bps and cable length will be less than a few hundred feet.

Will shielded CAT5 cable work well enough in this situation or should I pay the extra for "true" RS-485 cable such as this one?

I cannot easily visit the install site ahead of time as it's interstate.  I do have the same boards here in the lab I can test with however.


texts: OpenOCD child process termination: Wrong device detected

texts:
Setup

I have an STM32F103C8T6 minimal eval board (see STM32F103C8T6).

And I'm using an ST link like the picture below.

I installed System Workbench for Eclipse. I created my own project (C++, Empty Project, toolchains: Ac6 STM 32 MCU GCC),
Series: STM32F1, Mcu: STM32F103C8Tx, Core: ARM Cortex-M3, Package: LQFP48, Memory ram: Size 0x5000, memory ROM: size 0x10000.

Code

The code contains a system_stm32f10x.c file which was generated (or automatically included) by the IDE.

The program compiles ok:

  * @file    main.c
  * @author  Ac6
  * @version V1.0
  * @date    01-December-2013
  * @brief   Default main function.
  ******************************************************************************
*/

#include "stm32f10x.h"
#include <stm32f10x_rcc.h>

void delay(int counter)
{
    volatile int i;
    for (i = 0; i < counter * 10000; i++) {}
}

int main(void)
{
    GPIO_InitTypeDef gpio;
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);

    GPIO_StructInit(&gpio);
    gpio.GPIO_Pin = GPIO_Pin_13;
    gpio.GPIO_Mode = GPIO_Mode_Out_PP;
    gpio.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOC, &gpio);

    GPIO_SetBits(GPIOC, GPIO_Pin_13);

    while (1)
    {
        GPIO_SetBits(GPIOC, GPIO_Pin_13); // LED ON
        delay(400);
        GPIO_ResetBits(GPIOC, GPIO_Pin_13); // LED OFF
        delay(400);
    }
}

Upload by OpenSTM32

When I create a Run configuration (no changes made), and select Run I get the following error (in console):

Open On-Chip Debugger 0.10.0-dev-00302-gc211ca5-dirty (2017-07-03-10:41)
Licensed under GNU GPL v2
For bug reports, read
    http://openocd.org/doc/doxygen/bugs.html
srst_only separate srst_nogate srst_open_drain connect_assert_srst
Info : The selected transport took over low-level target control. The results might differ compared to plain JTAG/SWD
adapter speed: 950 kHz
adapter_nsrst_delay: 100
Info : clock speed 950 kHz
Info : STLINK v2 JTAG v17 API v2 SWIM v4 VID 0x0483 PID 0x3748
Info : vid/pid are not identical: 0x0483/0x374B 0x0483/0x3748
Info : using stlink api v2
Info : Target voltage: 3.231135
Info : STM32F103C8Tx.cpu: hardware has 6 breakpoints, 4 watchpoints
adapter speed: 950 kHz
Error: timed out while waiting for target halted
TARGET: STM32F103C8Tx.cpu - Not halted
in procedure 'program'
in procedure 'reset' called at file "embedded:startup.tcl", line 478
in procedure 'ocd_bouncer'

** Unable to reset target **
shutdown command invoked

Connections

STlink SWDIO pin 2 -> pin 7 of JTAG
STlink GND pin 4 GND -> pin 4 of JTAG
STlink SWCLK pin 6 -> pin 9 of JTAG
USB -> USB ( STlink 3.3V pin 8 not connected, neither all other STlink pins)

Schematic

Debug configuration file

# This is an F103C8T6_Simple board with a single STM32F103C8Tx chip
#
# Generated by System Workbench for STM32
# Take care that such file, as generated, may be overridden without any early notice. Please have a look to debug launch configuration setup(s)

source [find interface/stlink.cfg]

set WORKAREASIZE 0x5000

transport select "hla_swd"

set CHIPNAME STM32F103C8Tx

# Enable debug when in low power modes
set ENABLE_LOW_POWER 1

# Stop Watchdog counters when halt
set STOP_WATCHDOG 1

# STlink Debug clock frequency
set CLOCK_FREQ 4000

# use hardware reset, connect under reset
# connect_assert_srst needed if low power mode application running (WFI...)
reset_config srst_only srst_nogate connect_assert_srst
set CONNECT_UNDER_RESET 1

source [find target/stm32f1x.cfg]

Run configurations screen

Update

I could send a program via the Link utility, see below. I don't see a blinking light, but maybe the program is incorrect.

However, this way is not very comfortable (and I don't see any program running). Also, I still cannot debug this way.

PROBLEM SOLVED

See my answer (to help others with the similar problem)

Thank you all very much for your answers and numerous useful remarks.


texts:
I'm used to seeing a load resistor in the place of the yellow highlighted (Q2) section of this FET amplifier circuit.

This is the input section of a guitar overdrive effect, so any distortion created is likely not a problem.

Is this an active load to increase gain or something more / something else entirely?