texts: Type-C Non-Negotiated Power and 20V protection

texts:
I'm developing a 5V device and I use 5V for powering/charging the device. I googled the subject of course, and came to the conclusion that 5V device should have 20V protection in case there is some knock-off charger that will send 20V before finding out the target device didn't negotiate for such voltage. I have two questions:
Point number 1:
How much power do type-c power bricks provide if there is no CC negotiation and I just connect its 5V VBUS to my charging/PMIC*? How many amps do I get at 5V by default? I need to decide whether I need to include USB IC or not. Does it have to be some QC+PD combined IC to cover all range of chargers? The whole charging standard mess is killing me. Any ICs you could recommend? While I believe that some 500ma should be enough for my project, I wanna know the number I can look at and decide, besides, charging at higher currents wouldn't hurt. I have place on PCB and budget to put an IC or two, but if there's no need, I wouldn't overcomplicate.
Point number 2:
Do I need to protect from accidental 20V input? If yes, what are the options? I just put a 5.1V Zener on Type-C VBUS, so that it will clip 20V spike before the charger realizes 20V are not needed. Will it work? Do I need a separate protection IC or some negotiation IC with 20V+ tolerance? Or is it maybe all unnecessary?
*PMIC: SY6926QYC on LCSC, looks capable, charges, provides power to system (it bucks USB 5V down to charge battery with CC/CV and provides straight USB's 5V to the system or it boosts battery to 5V and powers the system with 5V again if no charger), can limit charging/system etc currents with external resistors, all-in-one, looks really lovely, but handles 18V max, had to design custom footprint for it too (eagle lib), haven't tested it before, but I kinda like its functionality, so I would want to stay with it.
I insist I wanna use USB Type-C port (no micro-B)
Edit: I've added a regular diode to zener to shift overvoltage threshold, since Zener will start to conduct before it reaches zener voltage, and I don't want to waste power. After all, the PMIC can take up to 18V with recommended maximum of 16V, so if I clip it around 6V, it should still be fine and waste less power. So there's 5.1V and 0.6V from a diode now. I guess it should help, but there is still no detailed answer anywhere to be found. Or maybe I could go for two zeners or a zener with higher voltage, I guess.
Edit 2 (01.08.2020): I've decided to try to implement power delivery and use a chip that can withstand 20v. I will cry when I write software for it (it's an I2C controlled PD controller), but it's useful experience, and I can afford it in terms of time and costs.


texts: Vibration sensor, using centripetal accelerometers

texts: To measure (a) rpm and (b) whirling of a drive shaft, I have built a sensor with 3 centripetal accelerometers arranged at 120 degrees separation around the circumference of the housing. The maths indicates that rpm can be calculated from: Arpm = (A1 + A2 + A3)/3  and the whirl speed from the maximum value of: Awhirl = A1 + A2(cos120) + A3(cos240). The rpm calculation works perfectly for any shaft inclination between horizontal and vertical. However, the whirl calculation is only correct when the shaft is horizontal. I have had a second opinion on the maths and the whirl calculation should work at any inclination. So, I wonder if there is something that has been missed with regard to the accelerometers, which are Silicon Designs 1210J-005 (capacitative/analog) and respond to dc and ac accelerations.


texts:
What kind of electronics is need for depth perception of objects? I know that having 2 cameras  is one method, but what about ultrasonic? Can I determine depth through that? In my project I am dealing with computer vision, and I require depth perception without the additional camera. Still a little stumped on what to do....

more specifically I'm trying to build a robot with computer vision using a single camera. I need to deal with depth specifically in object recognition. Typical object recognition training requires for the object to be set in an environment with a clean blank background. But with depth perception this isn't necessary. However since I'm limited to a single wireless camera, I have limited means of accomplishing this.

So essentially if I could use a kinect all my problems would be solved, unfortunately there are various restrictions that limits me to a simple wireless camera.

thanks!


texts:
We are struggling with part iv of the question above where we have to find the width of both MOSFETS. As you can see from our working out, we have found a width of 2 meters for the nMOS, which we know is way too big.
Is there something wrong with our working or are we going about working it out completely the wrong way?

\$First \space find \space I_b:\$

\$\beta_f = \frac{I_c}{I_b} \approx \frac{I_e}{I_b}\$

\$Rearrange\space to\space find \space I_{b}\$

\$I_b = \frac{I_e}{\beta_f} = \frac{3mA}{200} = 1.5 \times 10^{-5}A\$

\$I_d \space (of \space MOSFET)= I_b\space (of \space BJT)\$

\$Substitute\space I_d\space into:\$

\$g_m = \frac{I_d}{V_{Th}} = \frac{1.5\times 10^{-5}}{25mV} = 6 \times 10^{-4} \$

\$Now\space using:\$

\$g_m = \frac{2I_d}{V_{gs} - V_t}\$

\$Rearrange\space to\space find \space V_{gs}\$

\$V_{gs} = \frac{2I_d + g_mV_t}{g_m} = \frac{(2 \times 1.5 \times 10^{-5}) + (6 \times 10^{-4} \times 0.8)}{6 \times 10^{-4}} = 0.85 \$

\$Now\space using:\$

\$I_d = \frac{K'}{2}\frac{W}{L}(V_{gs} - V_t)^2\$

\$Rearrange\space to\space find \space W\$

\$nMOS \space W = \frac{2I_dL}{K'(V_{gs} - V_T)^2} = \frac{(2 \times 1.5 \times 10^{-5}) \times 5 \times 10^{-6}}{3 \times 10^{-8} \times (0.95 - 0.8)^2} = 2\$

\$pMOS \space W = \frac{2I_dL}{K'(V_{gs} - V_T)^2} = \frac{(2 \times 1.5 \times 10^{-5}) \times 5 \times 10^{-6}}{1 \times 10^{-6} \times (0.95 - 0.8)^2} = 0.06\$


texts: I am using the IO pass through mode on an XBEE, so basically if one XBEE has a high input, it passes that input to the other XBEE and that XBEE's output is also high. Since the Raspberry pi has an output GPIO voltage of 3.3 and the XBEE takes in 3.3 volts in digital in, can I just pass the output of a RASPBERRYPI GPIO pin to the input of a XBEE pin?


texts: CE/FCC/RoHS/etc certification for Intel NUC and other barebone MiniPCs?

texts: Intel sell the Intel NUC without a hard drive or ram. They provide a list of compatible rams and drives. By sliding in the ram stick and drive, am I not invalidating all of the certificates on the bottom of the unit?


texts: I2C single-master: Does the master have to implement repeated start?

texts:
I am implementing a minimal I²C master, trying to keep it as simple as possible (but as complex as necessary).  This master is a hardware peripheral - you could consider it part of an FPGA design, controlled by software.

The initial requirement for this project is that it supports multiple slaves but not multiple masters on the bus, so I'm wondering whether I need to implement the ability to generate "repeated start" conditions.  As far as I understand those are only required retain control of the bus in the context of a multi-master setup; this is explained rather well on i2c-bus.org.

Are you aware of any slaves that strictly require the use of repeated starts? The I²C page on Wikipedia gives an example of a 24C32 EEPROM which uses repeated starts for random access reads, same is said in  the part's data sheet. But neither sources mention whether it would also work with separate WRITE and READ transactions where each transaction is terminated by a STOP condition.


texts:
This is a PCB with few stepper drivers.

I have a question about the ground plane. I have this idea to split the ground plane for each driver, so, I force the return path to pass through the capacitor.

What is your opinion about this? the cut may create some noise, and it will affect the thermal dissipation.

thank you!


texts: How does gnu linker obtain Cortex-M stack pointer value?

texts:
GNU's linker obtains the ARM Cortex's stack pointer value from the linker script, and places that value in the first location of the interrupt vector table.

I note that most of my scripts use the symbol _estack to define the "end of stack" (memory region--which is actually the "top of the stack"), which is also the value the linker uses to populate the vector table's MSP location in the final linked image.

Is _estack the (required) symbol the linker uses to generate the MSP?  Or, is there another symbol or mechanism GNU's linker uses/can use?


texts: Alternator current when charging flat battery

texts:
I've found some voltage-current-rpm graphs for car alternators and did not quite understand one thing.
Basically, my alternator is rated at 75A (small car), which it should output above 2000 RPM or so. Below this RPM, alternator will output less current (due to lower input power (rpm*torque)). In any case it will try to maintain a voltage between 14.0-14.4V unless overloaded, when voltage will drop.

Now, lead-acid batteries should be charged at 0.1C rate (10 hours) to maintain their health. Anything quicker and you will be buying a new one soon. So, what happens, if I install a healthy (low internal resistance), but only barely charged battery? If I connect 14V to it, it will draw 50 amps easily. However, to maintain battery health, the current should be limited to 5A or so (for 50Ah battery).

The question is: is there any kind of current-limiting mechanism for this scenario, to not kill the battery? Or should we all assume that we should buy new batteries every year, if we don't use the car often and let it discharge to 11V?


texts: Which is better: using a resistor with an LED, or "precisely" matching the Vs to the given LED's Vf rating?

texts:
Here's an example:

Suppose I have an LED with a Vf rating of 3.6 V ....Here are two things I could try:

1) use a single 3.6 V 18650 Li-Ion cell with no resistor [\$V_s = V_f\$]

or

2) use three 1.5 V alkaline cells in series [4.5 V] in combination with a resistor... And yes, I would use the "optimal" current rating for the LED to calculate the desired ohms for the resistor:

\$R = (V_s - V_f) / I\$

My guess is that the first configuration will be more efficient, but the second configuration (with the resistor) will result in greater "brightness consistency" over time [the voltage decreases in both configurations as the batteries discharge.]

What do you all think?


texts: How can I divert current to higher resistance components in parallel?

texts:
I am working on a circuit and I need to divert the current to higher resistance components in parallel without changing their voltage input. There are 4 thermoelectric devices (T1, T2, T3, T4), a heatsink, and a pump. They all ideally need 12 volts but the heatsink needs 0.09 A, the fan needs 1.1 A, and the thermos can take any current. The battery is 12V and 2.9 Ah.

Since the thermoelectric devices have such a relatively low resistance, nearly all the current goes through them and none will go through the pump or heatsink as shown in the schematic below. Is there some component that will help divert the current to the pump and heatsink? We are avoiding using extra batteries due to the weight and ease-of-use.

We have run out of ideas since we have limited experience with circuits. Any suggestions would be greatly appreciated. Thank you!


texts: Would reducing the reference voltage of an ADC have any effect on accuracy?

texts:
Regarding the following information taken from a paper:

The paragraph is telling about what happens when the ADC Vref is reduced.

There is the statement from the above quote:

  Note that if you reduce the reference voltage to 0.8V, the LSB would
  then represent 100mV, allowing you to measure a smaller range of
  voltages (0 to 0.8V) with greater accuracy.

Isn't it wrong to say "with greater accuracy"? Shouldn't it be "with greater precision" instead?

(I'm asking because if I don't clarify this point, I will be misunderstanding all the rest)


texts: Transistor action, transistor as an amplifier

texts: On Using the transistor as amplifier,  does the Current Gain stay constant by changing base current or R base?


texts:
Trying to understand this circuit. What is the resistor R1 for?
Wouldn't it just continuously supply voltage to the base and make it always "ON"?

Another version:


texts:
I will try to sum everything up and keep it as clear as possible.

I have a solar system:

inverter: 1500VA 24V system
batteries: AGM 100Ah (20 months old daily cycle)
controller: semi-MPPT 80A 24V

Setup:

Suddenly my system started shutting down quickly because of low battery, after testing I noticed that batteries (2,3,6,7) were 10.5V while the rest were 12.5V.

I took them all out, balanced them all and returned in the exact same order and were charged to 100% (27V,13.5V/Bat.), within 48h the problem occurred again, so I decided to take the 4 bad batteries out and balanced the good batteries voltage, this is how the system looks like now:

Within 24h and after fully charged and used I tested it and found out that batteries (5,8) were 10.5V while the rest were 12.5V

What could be the cause? This has confused me a lot! Has anyone seen or heard of this phenomenon?

I don't really know how to approach or diagnose the problem

Load: max estimate is 1.2Kw used since sun down until tests time


texts:
I need a 15kV or higher power supply. I found 2 used neon sign transformers rated at 10kv. Can I use both of them and connect the secondary coils in series to get 20kV?

I am not sure if 15kV isn't overkill. I need voltage that is big enough to ignite a spark between 5-10mm. I read that the value is 30kV/cm, so I assume 15kV is good enough to jump 5mm.


texts: How to draw a polygon with clear spaces inside in EAGLE

texts:
As title EAGLE don't allow me to draw a clear space inside a polygon. I've a GND polygon plane and I don't want that a zone inside it is filled with this plane.

How I can do that?


texts: Use a SIM card module (SIM808) with the less battery possible

texts:
I'm using a SIM808 module (on a breakout card) and I want to send only 20 bytes every 6 hours (i.e. 120 bytes per day), containing GPS position and some very short other data.

So I think I'll probably have to use an Arduino. In order to use the less battery-possible, should I:

Have the Arduino running fulltime (with sleep most of the time), and GSM connected all the time
Have the Arduino running fulltime (with sleep most of the time), and GSM off most of the time, and GSM turned on only 1 minute every 6 hours
Have the Arduino + GSM completely off most of the time, and have a timer chip (what chip?) powering on the Arduino + GSM chip only 1 minute every 6 hours.
Another idea that would use even less battery?

Obviously 1. is not optimal at all. Would you use 2. or 3. (if so, how?)


texts: Is possible use driver and receiver from different RS232 IC?

texts:
I need RS232 IC with Features: power supply 3.3v, ESD protection, 8-drivers/8-receivers.  I'm looking for ic with these specifications are not found.

These needs can be met if I use two IC is SP3244E (3-driver/5-receiver) and SP3249E (5-driver/3-receiver). My question: Can I use two IC above if I need 8-driver/8-receiver? Thanks.


texts:
I've just received an answer to a question that's resulted in re selecting an inductor.  So I'll be using something like this:-

(It's from here). How are these mounted?  There's only two wires which lie in a plane therefore the component will rock or swing and the leads quickly fracture.  Is this a case for kludging it on with lots of hot glue?


texts: I think I am confusing the difference between some of the of busses, such as IDE, SATA, USB, and PCI.  What is the relationship between all four, how are they connected to each other? From what I read it seems like PCI connects them together as well as to the CPU, but it's not clear.  Any help would be greatly appreciated. I am cross referencing this post with another I made about the Linux commands to browse them.  https://unix.stackexchange.com/questions/27414/ide-and-pci-bus-commands


texts: Why are orange diode lasers still not common although orange LEDs have been around for decades?

texts:
Nowadays you can find lots of cheap laser diodes emitting light at wavelengths such as 405, 450, ~640, ≥780 and, since recently, also ~520 nm. But it's really hard to find a laser diode emitting at 590 nm or around that (if they even exist yet). It's moderately easy to find (very expensive) DPSS lasers with sum-frequency generation—but not a diode one.

At the same time it's very easy to find orange LEDs. They have been around for decades: I had a cell phone with orange backlight about 20 years ago. So apparently, making p-n junctions in semiconductors with the necessary band gap has long been possible.

What is then the reason that orange diode lasers are still not common (or don't exist)?


texts: Can I extrapolate battery power by a brief observation?

texts:
Part of the research we are conducting requires us to estimate how detrimental our proposed algorithm to the battery life of the wearables. To do so, I opted to simply charge the wearable to 100% and have it operate for an hour while sampling the battery percentage on a per-minute basis. After that, for example, if the battery level has dropped to 95%, I'll reason that it consumes 5% battery per hour, hence it has a battery life of 20 hours.

What makes me consider this thought is my previous experience with battery-operated devices, specifically smartphones. The time required to have my old phone go from 100% to 95% was significantly longer than it took it to go from, say, 50% to 45%. Furthermore, the former timing was also influenced by how long the phone stood in charge after it was fully charged.

With this observation, I'm not sure if following an experiment procedure as described would yield reliable results. What would be the correct way to proceed with this? The device in question is a series 3 38mm iWatch.

Lastly, I'd like to apologize in advance if I'm not using the correct battery terminology.


texts:
I'm trying to draw up a part in EAGLE, but am having a hard time making out the datasheet dimensions:

For example, with the pin width, it's not clear whether it's 0.51 (mm, I presume) or 0.31. Likewise with width, is it 4.00 or 3.80?

This is a SOIC package, although I understand they vary from one to another. As a side question: what dimensions would be suitable for the pads?

DATASHEET: http://www.ti.com/lit/ds/symlink/lm4140.pdf


texts: Microcontroller VDD and VSS pins are shorted. Does that mean the MCU is fried?

texts:
I recently created my own breakout board for a STM32F030R8T6 MCU. The attached image shows the PCB that I designed for it. There are no components, only top copper tracks that get connected to header pins that is connected onto a breadboard.

Procedure:

soldered the MCU on the PCB board and tested it for any short connections etc...
Plug the PCB board into the breadboard and connect all the power and ground pins, I added 100nf ceramic capacitors as close as I could to the PCB board.
Connect all the 10k resistors acccording to the schematic diagram
Once that was done, I continued to connecting my ST link/V2 to the board, I only connected pins SWIO, SWCLK, GND & NRST (I left the VDD pin and TVCC pin as I understand it is only there to detect voltage).
Connected my power supply to the power rails and applied 3v.
Connect ST Link/V2 to laptop and open ST utility and try to connect to target.

This is where my problem starts. It says the programmer is unable to connect to target. I have tried everything from changing frequencies and connecting the MCU under reset mode, but nothing worked. So I looked at my power supply and I noticed that the current was varying between 10mA to 0.4A. Strangely the power supply didn't display that there was a short circuit. This is when I took my good old multi meter and did a continuity test and realized that my VDD and VSS pins are shorting.

I am not sure if my MCU is fried or if my ST link/V2 is faulty?

Extra Info:

I have tried resetting the MCU but that didn't do anything.
There was a short period where I was able to connect to the MCU but after 3 seconds the utility program will give me a error message that it has lost connection with the target and that I must check my power rails which I did repeatedly.

I would gladly appreciate advice and help as I have gone through 4 MCU and I only have 2 left.


texts:
I'm trying to build a Tesla coil but in my country find the necessary parts for this is extremely difficult. Currently I have everything but the top capacitor.

I want to use a toroid, but find a perfect one is no possible, so I'm building it from a metal pipe. The upside view will be like an octagon.

My questions are:

This will be as effective as a perfect toroid? Or at least a viable solution?
Where should I connect the secondary coil with this capacitor?


texts: Can an alternating magnetic field be "informationally" shielded?

texts:
I have asked previously about the properties & shielding of the "static" magnetic field previously, where I have determined that static fields are hard to shield.

However what I am really interested in, is that is it possible to shield against an alternating magnetic field, in the sense that can the information itself be blocked?

When I refer to shielding I don't just refer to EM shielding but also information shielding.

For example:

We put a radio transciever a metalic box to act as a shield.
The metalic box can easily shield against the electric field going out or going into the box, therefore we can't send out signals from the box, since the electric field is blocked by the shield.
So far so good, the electric field doesn't leak information, however that electric field can have an alternating magnetic field. (static field doesn't matter as pointed out above)
So if we put a magnetometer ouside the shield, can the magnetometer pickup the signal from the transciever? It may be electrically shielded, but the magnetometer looks for the magnetic field, and therefore the information can go out via the magnetic field?

Some people have pointed out that eddy currents could be generated by the alternating magnetic field , that would manifest itself in the shield. So the eddy currents would cancel out the change in the alternating magnetic field, and make it static.

So I don't quite understand this phenomena, my point is, I don't care if a static magnetic field goes out from the box, which will inevitably do according to the answers on my earlier question.

So a static magnetic field will go out, but that's no issue (since it can't carry information)
But will the alternating magnetic field succesfully be stopped by the eddy currents, or will the magnetometer pickup the information leaking out from the box?

In other words, can information be sent out from an electrically shielded environment via alternating magnetic fields? How effective is an electrical shield against information blocking that may be carried by magnetic waves?


texts: Electret microphone amplifier to control an LED strip

texts:
First sorry about my English. So my problem is so simple but I can't figure it out. I have a frequency to voltage circuit which is working perfectly but I want to control it by the voice.
https://youtu.be/lU1GVVU9gLU
I put a link here to show how I want it. The circuit is the same. I just need a microphone and an amplifier but I don't know how to do this.
Any help would be appreciated.


texts:
When BJT's collector and base are shorted, then what happens for the circuit or may I say the change of BJT's performance  in the circuit as there Vbc is zero.

simulate this circuit – Schematic created using CircuitLab

Is it work like normal BJT where there is Ic and Ib current ?

Or, It just work like a diode as there is only one biasing voltage difference between one pn junction and zero voltage difference ( so no foreword or rivers bias ) for other junction?


texts: I am planning to use the SPIM08HP pouch cells from batteryhookup.com for their crazy power. They have an extremely high discharge rate at 25c, but I have heard that under heavy load, pouch cells will start to build up gasses in the pouch and expand. Is there any way to prevent this other than pulling less current? Thanks!


texts: How to connect a windshield wiper motor to a DC power supply

texts: I bought a 12 volts wiper motor  and am trying to connect it to a 12 volts DC 4.2 amps power supply. There are 4 terminals on the motor. I'm confused regarding which terminals that I should connect the positive and negative ends of the power supply to. When I connect the positive and negative wires from the supply to the two leads on top side of motor terminal (circled in red in the first picture), the motor turns very slowly and I can observe the power supply LED flashing which indicates a voltage drop. Can anyone please help me with the connections ?


texts: Design of an electronic device to disable remote access ability of contactless payment cards without visible alterations and damage to the card

texts:
Question: How could I build an electronic device which disabled the remote interaction functionality of contactless payment cards while not affecting the functions which are accessed via the on-card contacts or magnetic stripe (where equipped)? I am looking for a DIY technological solution that I could implement myself or suggestions about how I may be able to design and build such a system.

NB: The device would be used by me or other owners of such cards to control access to the card's facilities and to prevent fraudulent access. The desired system has no known fraudulent or illegal aspects.

Background:

New chip-and-pin cards come with an antenna which is a coil made of five or so turns of wire (fractions of millimeter thick) located typically along the card perimeter. The antenna is connected to the chip which also has the contact pad used for connecting the card to the terminal when not using the wireless technology.

One important design aspect is that all the turns belong to the same imaginary plane - they are "parallel" (no intersections) to each other and the gap between adjacent turns is more or less constant and is roughly the same as wire diameter. See this and this for pictures of the antenna layout.

There's a bit of paranoia about payWave/PayPass contactless payment features (see this, this and this questions on Money SE). People want to keep all the card features (the card body itself, the stripe and the chip) but disable the payWave/PayPass feature.

Once their banks refuse to disable the feature cardholders proceed to mechanical card alterations - they locate the antenna and either drill through it or slightly cut it with a knife. Typically they succeed but I'd be curious to see the eyes of a cashier who sees this card with two ugly holes one of them through the magnetic stripe. Clearly this may raise a lot of concerns and perhaps even cause an arrest in some cases.

Is there a way to go without notable damage?

Basically we have a small chip which we want to stay intact connected to a coil of very thin wires located in the same imaginary plane (no intersections) all embedded into a thin layer of hard plastic and we only want the coil disconnected in any one point so that it no longer forms a closed circuit.

How can this be done without drilling/cutting/punching a visible hole in the card body?


texts: Should I connect unused STM32 pins to ground?

texts: I'm designing some circuit using STM32L152RBT6 microcontroller. I'm using STM32L-DISCOVERY scheme as a reference of good STM32 practices. I've noticed that free pins of programmer's MCU aren't connected to ground (of course, they can't be connected at demo MCU in the second part of the circuit). I know that leaving free pins not grounded is acceptable in TTL-based circuits, but CMOS technology (on which STM32 MCUs are based) is different. It uses polar transistors. Ideal polar transistor consumes power only at the moment of switching. Also they're driven by voltage and leaving pins free should increase power consumption because of noise voltages. I've heard that grounding unused pins is a best practice to reduce CMOS power consumption. Should I ground all unused pins like on the scheme?


texts:
I'm having some trouble getting my memory to GPIO DMA circular settings right. The initialization code pasted below has some issues.

I'm trying moving data from a uint16_t array to the GPIO->ODR register. I have the source and destination both configured as halfword since they're both 16-bit registers. My array is 48 bytes long, and I want to transfer 96 bytes (the 48 byte array 2 times). So I want the DMA to shift out the 48 bytes, then go back to the start of the array, and do it again with the same array.

However I'm not clear on how to tell the DMA after how many bytes to circle back. If I set the buffersize to 96 it just keeps reading 48 bytes past my array.

void WS2812_Basic_DMA_Init2(void)
{
    DMA_InitTypeDef DMA_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);      // Enable DMA1 clock

    DMA_DeInit(DMA1_Channel2);                              // Reset DMA1 channe1 to default values;

    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;            // M2M Disabled- Peripheral mode (requires timer trigger)
    DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;         // Circular mode
    DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh; // High priority
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;      // Memory to Peripheral

    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord; // 16-bit Register
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;            // Always write to same register
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&GPIOC->ODR;           // Output data for GPIO

    DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;         // 16-bit array
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;                     // Increment through array
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)&source16;                 // 16-bit Source data

    DMA_InitStructure.DMA_BufferSize = ARRAYSIZE;           // Size of source array x 2

    DMA_Init(DMA1_Channel2, &DMA_InitStructure);            // Initialize DMA

    //Enable DMA1 channel IRQ Channel */
    NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    // Enable DMA1 Channel Transfer Complete interrupt
    DMA_ITConfig(DMA1_Channel2, DMA_IT_TC, ENABLE);
}


texts: What are the characteristics of this capacitor?

texts:
I need to replace this capacitor on the dynamo of my electric generator.

Beside being 20µF, what are the important characteristics that I should look for in a replacement?


texts: Deflection coil/yoke needed - any ideas on where can I get it?

texts:
One of our molding machines screens has stopped working well. We've found out that the deflection coil has been burnt at glueing area and few wires have disconnected.

Maybe somebody here knows if there's any way to regenerate this fairly easily without specialist tools?

Symbols on coil are: vs-58485 and A94Z8ct

The screen is Microvitecs 13L4S4033ASX


texts: Linear vs Switching Regulator for Computer (22VDC to 12VDC @ 1A)

texts:
For a robotics project I need to use a buck regulator to power a mobile computer from a 22V LiPo battery. I am currently using this LDO regulator and am having issues with it getting very hot. Using a large heat sink, the regulator functions without shutting off due to high temperature yet since this is a mobile application I am worried about how much energy I am wasting in the form of heat. If my load is pulling 1A at 12V, is it true that the regulator is dissipating (22*1) - (12*1) = 10W? I had originally selected a linear regulator over a switching regulator because I wanted a clean, stable DC output for my computer to operate on.

I am now thinking about trying a "switching regulator" because of how most of these devices are >90% efficient! I have had a lot of trouble finding a switching regulator that could provide a 12V output (most of them seem to provide only a few volts of output, does anyone know why this is?). I found this switching regulator though which provides my needed output and is in the 90% efficient range. Does anyone have any suggestions for other switching regulators? I have to have a totally integrated package (for example, I don't have room to attach external caps or inductors for my application).

Also, is the only reason someone would choose a linear regulator over a switching regulator because they usually provide higher voltage outputs? Is using a switching regulator with a computer really not a problem?


texts: Help please! I need to give constant current to an LED from a Lipo battery

texts:
I'm trying to drive an LED from a Lipo battery. The useable voltage range of the Lipo goes from 4.2V down to 3.4V, and the forward voltage of the LED is 3.2V. With a resistor in series with the LED, the voltage drop across the resistor will range from 1V [4.2V batt - 3.2V LED] to 0.2V [3.4V batt - 3.2V LED]. Therefore the current flowing through the resistor will drop significantly as the battery discharges.

So, I'm looking to supply a constant current to the LED over the Lipo's voltage range. I've tried using a basic typical constant current circuit (zener diode, transistor, and 2 resistors), however, the zener diode requires 5-10mA holding current, that makes the system inefficient because the LED requires only ~20mA.
I've also tried using a boost circuit (NCP1402) which provides a constant 5V output, but again this is quite inefficient (LED only receives 60-70% of power from battery).

Can anyone suggest a low power and efficient circuit that will keep the LED constantly powered as the battery discharges?

Thanks,

Andy_C


texts: Get practial resistances for the Current Divider

texts:
My understanding

The resistance as seen through the load is just Rs, Therefore 60K <
Rs < 80K.
Is (current Through Rs Resistance)
IL (current through RL load)
Is/IL = RL/Rs, because of the limit IL ~ 40uA we get Is as 60uA and RL = (3*Rs/2)

when I choose Rs = 56K and RL =  82K I am getting wrong answer. I understood that I am going wrong somewhere. Please let me know where I am going wrong.


texts: Two port networks - Why are shared Z-parameters not negative?

texts:
In basic electronics we learned that to solve a circuit using mesh analysis, the shared impedances had to be negative. For example in the circuit bellow, the system of equations would be:

$$\begin{pmatrix}
Z_1 + Z_3 & -Z_3\\
-Z_3 & Z_2 + Z_3
\end{pmatrix} \cdot \begin{pmatrix}
I_1 \\
I_2
\end{pmatrix} = \begin{pmatrix}
V_1 \\
-V_2
\end{pmatrix} $$

(The shared impedance (Z3) is negative).

However , now in our filters class we're learning that even the shared Z-parameters (Z12 and Z31) are positive. For example, the Z-parameter matrix for the cirucit above would be :

$$\begin{pmatrix}
Z_1 + Z_3 & Z_3\\
Z_3 & Z_2 + Z_3
\end{pmatrix}  $$

Can anyone tell me why this is ? Am I missing something ; do Z-parameters mean something different that the impedance matrix in mesh analysis ?

Thank you ,

Liam

(https://en.wikipedia.org/wiki/Two-port_network#Impedance_parameters_(z-parameters))


texts: Are there light circuits that can be cut and still work?

texts:
I need a way to have a light circuit that can be severed/cut and still work up to the point that it got cut.  I know that rope lights work that way, but they can only be cut at certain points, right?

Is there any way to have a length of LED lights that still work if I cut it at a random spot?


texts: Replace microphone signal with an audio signal taken from my phone

texts:
From researching on the internet I have learned that microphones output analog voltages and with the help of amplifiers they can store that variating voltages as digital data in case you want to store that audio.

Anyways I want to wake up Alexa by doing gestures as an alternative. On my phone I have a recording that says "Alexa how is the weather today". I want to send that audio to Alexa so that she responds without me having to talk for purposes of learning. Here is my approach:

disassemble Alexa and find the microphones. There should be 4.
Get an audio cable peal one side of it and solder it to one of the microphones of Alexa. I have a 50% chance of getting this right. I don't know what side of the cable goes to the positive and negative.
Connect the other end of the audio cable to my phone and play the audio on my phone.

If I do this experiment will it work?

Edit

I know I can play the audio on my phone to simulate this. I also know I can purchase the Alexa remote control that will wake her up. I am asking this for purposes of learning.


texts: What's involved in building your own RFID reader? As you guys would know industrial RFID readers aren't cheap, how do you energise the antenna, then read back the output?


texts:
I am wokring on a board that uses Micron 1Gb QSPI (mt25qu01gbbb8e12-0aat) to load configuration on to FPGA at power on.

As per the datasheet of QSPI (https://www.micron.com/-/media/documents/products/data-sheet/nor-flash/serial-nor/mt25q/die-rev-b/mt25q_qlkt_u_01g_bbb_0.pdf), it says STR max supported frequency as 166Mhz. (Time Perios - 6.02ns)

In the Serial IO timing diagram, they mention that the Clock to Output Valid Delay (Tclqv) for 10pF is 5ns.

If the delay on QSPi data output itself is 5ns, is it possible to have the QSPI boot working at max speed of 166Mhz taking into consideration setup time requirements of FPGA and propagation delays on pcb

I am confused if I am reading the timing diagrams incorrectly and not understanding what the Tclkq 5ns delay is for.


texts: Can I use ceramic capacitor instead of polyester film box type capacitor in SMPS

texts:
I am working on 5V 1A power supply. I've made circuit on GPB which is working fine. I just wanted to know whether can I use ceramic capacitor instead of film box capacitor.
Here is my schematic

C8 is shown in the figure is the film capacitor that I want to change. Switching IC is TNY266.
Please help


texts: 1 x 3 splitter with connecting cables for Wi-Fi RF calibration

texts:
So i have a 1 x 3 splitter, where i transmit a signal s(t) as follows

The purpose of the following setup is to find the different delays in each RF receiver (Cable->LNA->VGA->ADC). A clearer picture might be this

My question is simply, do the connecting wires introduce any "multipath" ? In other words, might the transmitted signal be received in delayed versions ? Or can i be sure that only one copy of my signal s(t) is being received.
P.S: I have no experience in splitter and connecting cable usages, but my application requires me to know the different delays across each path "Cable->LNA->VGA->ADC". Any advices or alternatives are highly appreciated.

Many thanks in advance.


texts:
So I'm trying to solder a power button onto my RPi 0. My issue is simple actually. I can't get the solder to melt onto the board. I've watched several videos all say the same. Basically to touch the pad with the iron then the solder to the iron tip and slide down fast. I tried this and either the solder just like evaporates or it beads up onto the iron or onto itself. I'm using lead-free rosin core solder 2.2% flux at about 350 C. I've basically melted the back of the pi which is fine since I bought about 15 because I assumed I'd mess up. Any insight as to why this is happening? I thought about maybe picking up some flux gel but in all of the videos I seen, none of those people used them nor had this type of trouble. Could it be my temps? I tried lowering them but it just doesn't melt the solder in that case.

EDIT: I've never actually had an issue soldering but I've also never soldered anything so tiny. Usually soldering for me was big boards for RC stuff.


texts: Purpose of 100 ohm resistor on guitar pedal output buffer

texts:
On the schematic for an Ibanez "Tube Screamer" there is a 100 ohm resistor in series with the output emitter follower:

The output impedance of this pedal is 1.2K:

It looks like RB has a negligable effect as it increases Zout to 1.3K
An explanation I've seen for this is:

To start with, the series resistance at the emitter limits the amount of drive available to drive an amplifier input (although not by much), and in concert with the series capacitor forms a voltage divider with the output shunt resistor and the input impedance of the amplifier plugged into it. This drops the available signal only a trivial amount, probably inaudibly so. (http://www.geofex.com/article_folders/tstech/tsxtech.htm)

Considering the next stage after this buffer is likely to be either a guitar amplifier or pedal with input impedance of approximately 1M ohm I don't understand why it is needed.


texts:
I am working on a project testing alkaline batteries and need a way to quickly measure remaining battery life. I would like to be able to estimate mA-h remaining in the battery. If I measure mA-h over a millisecond current pulse, is this an indication of used mA-h over that pulse or does it somehow relate to remaining mA-h?

If this is not an accurate test, any recommendations would be greatly appreciated.


texts: Reason behind the naming convention for the non-gate terminals of JFETs?

texts: Why, for an N-channel JFET, is the source terminal defined by convention as the non-gate terminal with the lowest voltage? Why does this convention swap for P-channel?


texts:
I'm just trying to work out the rules for this. I have 2x 9v motors running through an L293dne which may run together, one at a time, and/or, at different speeds using PWM.

I'm thinking an 18v battery with a 9v buck converter on each circuit would do it but can someone confirm this please?

Is there a better way?

Many thanks in advance.

Phil.


texts:
I inherited three of these Texas Instruments vintage ICs, marked N286 (regular size) and M26 (unusually large). The smaller pairs of digits on the right hand side, 74 and 18, are, I assume, the manufacturing date. Does anyone have any info on what these are?
I assume the date code is 18th week of 1974. They are in a standard 16 pin plastic DIP. I can't find any information about them, and the format of the marking isn't one I've come across before:

The underside is more than normally verbose too, marked E175A2M, in case that is of any help:


texts: What should I know about interference between wires in a multi-conductor cable?

texts:
I want to use a multi-conductor cable for a few different circuits. What do I need to know about interference between circuits within a multi-conductor cable?

Some of the wires will carry stepper motor coil supply and return. I suspect this will emit a lot of EMF due to large, rapidly changing currents, and should probably be shielded.

Other wires will carry optical switch supply, return, and output. This circuit is probably tolerant to noise and doesn't make much of it either.

Others wires could carry high-speed digital data. These circuits are probably susceptible to noise and might make some as well.

Can I run these all in the same cable? What else might I need to consider?

EDIT: Let's assume I'm talking about using a cable that has a single shield around all of the wires, instead of individually shielded bundles of a few wires.


texts:
Many laptop batteries have a button on the bottom that will light up 1-4 LEDs to indicate how much power is remaining.

I'd love to build something like that into my own device, which is powered by 2 18650 LIon batteries in series.

Is there a simple way to build a circuit that will light up different LEDs depending on the voltage of the battery pack?  Or a ready made IC that does something like this I could easily use?


texts: Phase Noise In a Voltage Controlled Oscillator

texts:
I am particularly new in VCO design. I am required to build a negative gm oscillator with f=7.4 GHz with a tuning range of 300 MHz. The phase noise should be -110 dBc/Hz at 1 MHz offset.

I sized the varactors in the circuit to have Cmax=550 fF, Cmin=330 fF with a tuning voltage of 1 V. The Tank capacitance was calculated to be around 2.2 pF/side with inductors of 190 pH, Q ~15. The differential transistors are sized 0.32/0.06 um process with bias current of 2 mA, 1 mA differential current. With many iterations with respect to changing the design variables I still cannot achieve the theoretical -30/-20 dB slope that is seen in typical phase noise responses in a VCO. All simulations are conducted in Cadence - Spectre
If there are any tips on how to fix this it would be much appreciated.


texts: How to design a cheap sine-wave generator up to 200 MHz?

texts:
I want to make a cheap wideband oscillator for an antenna analyzer I'm designing. I want a simple sine wave over a wide frequency range. I don't want to use a DDS IC like the AD9851 because it's expensive and feels like overkill.

I was looking at the SI5351A, which will generate a 50 ohm square wave clock up to 200 MHz.

I'd like to convert that square wave output into a sine wave over the range 1 MHz - 200 MHz. What is the simplest and cheapest way to do this?

Two ideas that come to mind are

Two cascaded op-amp integrators, using an OPA355 or something
A series of low pass filters that filter out everything but the fundamental, spanning the entire frequency range. For example filters with cutoffs of 2, 4, 8, 16 ,32, 64, 128, and 256 MHz? The correct filter would get switched to by an 8-port analog switch as the frequency rises. This seems like a lot of filters, but all these components are purely passive and would have relatively loose tolerances.

Does the approach of using a clock generator IC make sense? If so which of these filters make the most sense to convert the output to a sine wave? Thanks.


texts:
Hey all I am having an issue using this AMS1117-3.3 SMD:

According to its documents it says its either a fixed or adjustable version? So I hook it up as I see in the documents:

  The left pin (1) being Ground.

  The middle pin (2) being the 3.3vdc output.

  The right pin (3) being the 5vdc input.

Once I hook all those up, I test it with my voltmeter on 20 and i get a reading of 0.09vdc????????

I've already tried 3 of these to make sure I didnt blow it or anything but it keeps saying that readout.

Am I missing something here? This must be the adjustable version since I can not just hook it up and expect 3.3vdc to come out?

I also tried to just step down from 5vdc to 3.3vdc using 100ohm resistor but that only produced around 4vdc output....

Here is the way I hooked it up:

The document I am reading is here

And also on my breadboard:

And what I have it connected to (ESP8266 ESP-12f) this is its document stating above 80mA average:

Alright this is what I have to work with:

  2 x .1uF 100v Stack Metal Film

  2 x 1N4148TA 100v 0.2A

  2 x 35v 470uF

  2 x 25v 47uF 20%

  2 x 35v 220uF

  2 x 10v 100uF 20%

  2 x 1.0uF 50v 20%

Any of these work to step it down or use for the capacitors on the AMS1117?

Alright does this look like a good one to go by?


texts: Why do I need phase margin if I know the transfer function?

texts:
What is the point of examining the phase margin (or gain margin) for a closed-loop system if I can just solve for the transfer function. The transfer function will give any poles and zeros, which can be used to know if your system is stable, the step response, etc.

In fact, the Q of a two-pole system can be solved in terms of phase-margin, and vice versa.


texts: EAGLE. Differential pair routing. Width of the track changes after first change of direction

texts: I try to route differential pair of tracks. When I click the mouse to change the direction it also changes the width


texts: HMI for small desktop laboratory equipment

texts:
We are building desktop laboratory equipments and wondering whats the next step for HMI from 40x2 Text display and small switches.

Idea we are contemplating are...

bluetooth in device and android or ios phone
wifi or other zigbee protocol with webserver and phone
touch screen and full LCD

Our idea is to connect equipment to smartphone somehow ( bluetooth/nfc/wifi ) and display whole user interface on phone itself.

Best and Cheapest Idea I have is to connect equipment ( lets say, arduino ) to phone is via NFC ( which is a saparate device wired via a long wire to actual equipment ) to which one should attach their own phone, which enables the app to communicate directly to the device.

what you guys are doing as next step of hmi ?


texts:
I'm considering taking on a project that would involve individually addressing 500 LEDs, optimally with PWM support for each.

I'm planning on using an Arduino since I already have one, but I'm open to suggestions if anyone thinks a different platform would be a better match.

Shift registers would need to be employed. What is a good shift register to use in this situation? If PWM makes this project a lot more expensive, I'm alright to do without it. I want to try to spend less than $100. I'd bulk buy 500 LEDs off ebay.

What is your opinion on the best way to control such a large number of LEDs? Also, how would I go about providing the power? I'd appreciate any help. I'm fairly experienced with electronics, I've just never done anything on such a large scale.


texts: Calculate bandwidth of wide-band FM from spectrum graph

texts:
I want to calculate the bandwidth of my signal  output from the graph it results from application of the FFT.

I can apply the Carlson formula  knowing that I have all the parameters :$$B = 2(\beta +1 )fm$$ ,but what about the graphical solution ?


texts: Mechanical- Electrical circuit equivalence

texts:
Is this the right electrical circuit equivalent to the mechanical?

simulate this circuit – Schematic created using CircuitLab


texts: Some problems with my HP StorageWorks DAT 160 USB tape storage machine. Inside among others there is a SSOP28 chip named SR3437BBB2. Also there is another line with symbols 7CELR5KJ G4. It is made by Texas Instruments. Can not find any description of this chip, nor the datasheet..


texts:
I am trying to reverse engineer a pressure sensor thats connected to an ECM and outputs pressure ratings in bars.

i want to tap into the sensor with arduino and create my own voltage --> bars data.

This is the sensor wiring diagram, the sensor is "G31"

from my research, i am concluding that pin 3 is the Ref voltage from ECM, which is tied into another sensor (idk why). pin 1 is ground and pin 4 is signal.

i tested all 3 pins WRT to a known ground, while disconnected from the sensor but connected to ECM and power on.

pin 1: 0v

pin 2: does not exsist.

pin 3: 5.5v (ref)

pin 4: 4.95v (signal).

when i logged  pin 4 voltage WRT to ground, and callaborated that data to the known pressure, i got a graph that does not represent any function, it was literally a square blob of data.

2 possibilities for this:

1: Pin 1 (ground) floats, need to tap into ECM ground.

2: Reference voltage changes, need to log voltage drop WRT to ref.

do those 2 options make sense, and which would be most likely?


texts:
Got inrested in DIY fluxes by reply here.

Can you substitute rosin-core wire with DIY flux and non-rosin-core-wire?
How and where to actually use DIY fluxes if you have rosin-core wire?
Which % of ethanol and rosin should be used with SMD components?
Why to use a soldering flux? ( relates part 2)
With which substance you can avoid fungi? (relates to part 3)


texts: Speed control on a ceiling fan induction motor

texts:
I've managed, through the help of others here on Electronics StackExchange to get a ceiling fan motor running, at least at one speed, and in the right direction.

I want to enable 3 speed settings on the motor. How can I enable speed control of the motor?

I came across the following circuit diagram, is this method advisable? Won't this cause a lot of humming in the motor?

http://electronics-diy.com/1000w-ac-motor-speed-controller.php


texts:
Many Precision Rectifier Single Supply Op Amp circuits feed the input AC waveform into the non-inverting (+) terminal of an op amp e.g. see this schematic:

Image source: Precision full-wave signal rectifier needs no diodes
Say Vcc = +15V, Vee = 0V, and Vin is an AC input of +/- 5V (10V peak-to-peak), then when Vin is in the negative half-cycle, the first op amp outputs zero volts (it can't go lower), so input V(-) is also 0V via the feedback. Input V(+) however is controlled by the input AC voltage and will fall to -2.5V at its minimum. Now most op amp specs say under Absolute Maximum Ratings: Input Voltage "Vee-0.3V to +32V" say).
My question is, surely Vin at -2.5V is outside of the Absolute Maximum Rating of -0.3V? Also the Common Mode input at -1.25V is outside. So am I missing something? Any light anyone can shed on this will help a lot.
See
https://www.radiolocman.com/shem/schematics.html?di=161475
for the complete article.


texts: Two cables, same resistance, different lengths, speed of current transfer

texts:
If I have two cables, with different size, but in total the same resistance, what will be the speed of the current transfer( how much time will it take the voltage to appear at the end of the cable).

for example:
Imagine I have two cables, one in the legnth of 1 kilometer, and one in the length of 1 cm. They are made from different materials so in total the resistance of both of the cables is the same.
I plug the cables into a circuit, with a capacitor in series, and check the appearance of voltage in the capacitor. If I get just solve the circuit I get the following

Is this really to solution for both of the cables.. not matter what is the length of the cables?

Thanks


texts: How can I approximate the capacitance of a circuit, prior to building it?

texts:
I have recently gotten into FPGAs, and am interested in interfacing it with other, high-speed components (in general, not any one specific components).

Since time is a factor, and I have both resistance and capacitance, I have (as I understand it) an RC circuit, which will affect my signalling signal rise and fall time, limiting my speed.

The ICs & FPGA I will be using mention their capacitance & resistance in their data sheet, but how do approximate the capacitance of my circuit? What is the capacitance of perfboard (aka verboard), solderless breadboard, of a a solder joint? Of wire? a resistor?

Obviously, this depends hugely on the quality of the components, how much solder I use, the distance between the wire and surrounding wires, which is why I'm not asking about this specific circuit. I am trying to get an order of magnitude.

One of the comments suggested I build the circuit, and there is some value in that (especially for solderless breadboards), but I don't want to have to buy many components, to solder them up, and then throw them out, only to have to repeat the process with the next idea.

I have rewritten this question, because I do not want an exact answer for (this) one circuit, I want a general method. I don't want to come back to this forum to ask for each individual circuit, I want a general method/values. I also want to know, if the circuit I am thinking of is too slow, what are the major factors, how close am I, what changes would make a significant difference, and is the very idea even close to feasible?


texts: DC Circuit problem, an idea to solve this circuit?

texts:
So here is the circuit schematic:

Known values: \$E_6=200V\$, \$E=35V\$, \$R_2=50\Omega\$, \$R_3=100\Omega\$, \$R_4=140\Omega\$, \$R_5=120\Omega\$, \$R_6=100\Omega\$, \$C=10\mu F\$.

When \$P\$ is opened, capacitor load \$Q=1mC\$. When \$P\$ is closed, we know that the voltage across the capacitor \$C\$ is ten times lower than the voltage in case of opened \$P\$.

The task is to find \$I_{g1}\$ and \$R\$.

What I started with are the voltages across the capacitor.
In the first case (\$P\$ opened): \$U_{C1}=\frac{Q}{C}=\frac{1mC}{10\mu F}=100V\$
In the second case (\$P\$ closed): \$U_{C2}=\frac{U_{C1}}{10}=10V\$
So, \$Q\$ when P is closed is: \$Q=C\cdot U_{C2}=0.1mC\$

Could you give me a hint on what to do next? Just give me an idea and I think I can work it through.
Thank you for your time.

Edit:
Solution:
1) First, I solved the circuit when the switch is opened. In that case, I knew the voltage across the capacitor, which is: \$U_{C_1}=100V\$. Using superposition, I calculated the voltage \$U_{C_1}'\$ with respect only to \$I_{g1}\$ and then calculated \$U_{C_1}''\$ with respect to \$E_6\$.
\$U_{C_1}'=10I_{g1}\$ and \$U_{C_1}''=20V\$. Since I knew that \$U_{C_1}=U_{C_1}'+U_{C_1}''\$ I got \$I_{g1}=8A\$.
2) Now that I knew \$I_{g1}\$, I had to find \$R\$ and since I know the voltage across the capacitor when the switch is closed \$U_{C_2}=\frac{U_{C_1}}{10}=10V\$, the voltage across the resistor is then: \$U_R=U_{C_2}+E=45V\$. Then, I used mesh current analysis to get the current through \$R\$, and in the end I got: \$I=\frac{135}{R+100}\$. Then, using Ohm's law, \$U_R=R\cdot I\$ I got \$R=50\Omega\$.


texts: STM32L051K8U won't run without 3V when it should run at 1.65V

texts:
I've just switched the MCU of my board from a STM32L021K4T to STM32L051K8U and have a problem I can't figure out.

My circuit is powered by a CR2032 into a 2V LDO regulator and the original MCU (STM32L021K4T) ran perfectly with no problems. But the new MCU (STM32L051K8U) won't run without 3V, even though it say it runs down to 1.65V.

I've tried going through the datasheet to see if there some thing I need to set, but I'm at a loss.

The brown out reset option bit is set at 0 "BOR Level OFF, reset level threshold the 1.45V,-1.55V"

The voltage from the regulator is a steady 2V +/- 1mV.

To the best of my ability to tell, it never starts executing code. With the CR2032 in and the voltage being regulated to 2V, I can't connect to the chip with my debugger (I think it's because the debugger needs to see the chips voltage at ~3V). Sorry, if I didn't answer your question. I'm still pretty new to these. I appreciate the help though!

But, with the previous chip, what I'd do was program it with the 3V from my programmer. After it's programmed, I could disconnect and put int the CR2032 and it starts running.

With the new chip, I can program it the same way. But when I disconnect the programmer and put int the battery, nothing happens. I've bypassed the regulator and supplied the chip directly with the CR2032 and it works. Just not with the 2V from the regulator, when the previous chip worked (exact same board layout and parts).

So, it seems like to me that there is some option bit or clock configuration or something like that, that I have misconfigured. But I can't find anything wrong and anything seems related, when changed doesn't fix the problem.

Any ideas?

Thanks.


texts: Is it normal for me to be getting these warnings when I changed the names of the wires?


texts:
I have a question on connecting 3V EL wires to a 12V unit inverter. I know that is not okay to do so in a DC circuit, but I don't know if it is okay to connect them in an AC circuit.

Here is the link to the 12V unit inverter:
https://www.amazon.com/uxcell-Black-Cable-Driver-Inverter/dp/B00E0IVS0Y/ref=cm_cr_arp_d_product_top?ie=UTF8

Thanks in advance!


texts: How does having neutral make electrical systems safer than electronic systems which do not have neutral?

texts:
Electrical systems have neutral besides live and ground. Electronic systems have only VCC and gnd. I read that having neutral is necessary for safety in electrical systems because of the higher voltage and current involved.

How does having neutral make electrical systems safer?


texts:
I am working on a new project that seeks to implement a three-stage audio amplifier.  One of my stages consists of a CASCODE circuit using the BF998 NMOS transistor. For this stage I am struggling to mathematically build a circuit using this transistor and generate a gain with a specific harmonic distortion.

Initially I have chosen a region of operation for my circuit. By observing the graph Id x Vgs, I noticed that Vth is approximately -0.6 V and I chose to operate at VGS=0.1 V (Consider my input signal equal to approximately 260 mV)
My output impedance (other stage) is equal to 2637 Ω. Therefore, I have determined the minimum current required to keep my signal from clipping (Iout= 1.4364 mA)
Furthermore, I used a resistor bias and considered that the current passing through the resistor branch is 2000 times smaller than the current passing through the drain of the common gate.

From this, I don't know how to control the gain and set harmonic distortion for this stage. I would like to learn how to design these two quantities with mathematical relationships and then implement the circuit in Advanced Design System (ADS). What I have built so far can be seen in the image below:

For additional questions, I am always available to answer them. I am very interested in learning how to design this stage of my project.


texts: Does a VPWR capacitor on a high-side MOSFET switch guard against inductive kick back?

texts: We use three Freescale MC33982 high-side switches in parallel to drive a DC motor, and our electrical engineer suggests that a 50V, 10uF capacitor on the VPWR pin (then to ground) will guard against inductive kick back, but I cannot understand how, and I wonder whether someone here could explain how? Note, it's the location of the capacitor that confuses me, not how a capacitor could work as a shunt. (Also, this switch has an output clamp, but we are concerned it's not sufficient.)


texts: How to connect earthed metal chassis to DC ground?

texts:
I have around 12 purely DC PCBs inside a metal case. Each has a MCU which connects to the main controller PCB with SPI or I2C. Each is powered by one shared ATX PSU which also sits inside of the case.

Obviously the case and any exposed metal needs to be connected to Earth. But every PCB is screwed directly to the case and around 4 PCBs have metal connectors or Pots that also touch or are screwed to the case.

I am struggling to get my head around what to do in regards to DC Ground and Earth, do I connect them if so how or do I isolate them?

I can't find any info on how this is done in a commercial application which would comply with the relevant EMC and safety standards.

What should I do with the shells of the Pots and Connectors on the PCBs? They are going to be connected to earth through the case, so should I isolate them from the DC ground on the pcb?

What should I do with the mounting holes? Should I have them plated and connect the DC ground to earth or should I not plate them and leave plenty of clearance around them for the screw heads?

It seems like I have the following options:

Connect DC Ground to Earth, it then wouldn't matter about the Pot and Connector shells.
Connect each shell to to DC Ground via an 1M/4.7Ω Parallel RC Tag. This would only be ok if each shell made a solid connection to earth.
Have a separate Earth plane on each PCB connecting the mounting holes to the shells.
Leave the shells and mounting holes completely isolated from the DC Ground on the PCBs


texts: Understanding Fourier, signals and spectrum analyzer

texts: I'm having a hard time grasping the relation of Fourier analysis to the nature of signals and spectrum analyzers. From what I understand, Fourier analysis gives us a mathematical representation of a signal, but we don't need a infinite number of harmonics to make a square wave, for example. So if I put a perfect square wave signal into a spectrum analyzer, using simple 5v on/off switch, it will "see" all diferent harmonics or not? Maybe my question is: A specturm analyzer will have an algorithm to do a Fourier analysis of a signal or will actually perceive different frequencies? Sorry if my question is naive or hard to understand, im still a student.


texts:
I want to precisely measure the forward and reverse power on a high-voltage power supply that operates from 10-100kHz, at power levels on the order of 20W.  To do this, I need to make or buy a directional coupler with a fairly weak coupling constant of 20-40dB.

For systems operating from 100's of MHz to GHz, I have built simple 1/4λ coupled transmission line directional couplers with a bit of stripline. A coupled transmission line design does not seem practical for 10's of kHz, so my intuition is that I'll need a discrete element directional coupler.  Ham radio sites have lots of tutorials on high-frequency coupling, but I'm having trouble finding resources for coupling at low frequencies.

What topology should I consider for a directional coupler at this frequency, power level, and coupling constant?


texts:
So I've got a huge battery at 96VDC with a couple of electric motors hooked up to it that can draw huge amounts of current -- up to 600 amps.  I need to power a few small electronics for a data acquisition system off this battery.  If I were to guess, these components wouldn't draw more than 50mA.

I don't have the battery yet but if I were to guess, this 96V won't be very stable as the current draw is going to surpass the rated capacity of these batteries.

What's the best way to get a 3.3V supply rail off this type of battery?  Would an LDO be the best solution here?  Any suggestions on filtering the input, knowing that there will be these motors also hooked up to the battery?

Thanks


texts: How to measure capacitance of soil without being affected by resistance?

texts:
I want to make a capacitive soil moisture detector. Capacitance of soil increases with increasing moisture content. Resistance of soil decreases with increasing moisture content. The soil capacitance is considered a more accurate indicator of the moisture level.

If I have 2 capacitance plates buried in the soil what general type of circuit can I use to measure just the capacitance?

I know that these type of detectors use about 10MHz sine wave across the plates, but I can't find more detailed circuit information online.

I though perhaps the soil capacitance would be used with a fixed inductance to make an oscillator. Then the frequency of the oscillator would be related to the soil capacitance.


texts: Is it possible to program an STM32 with an Arduino board only? (no FTDI, no STLink)

texts:
I wished to start using STM32F103C8 board (bluepill). I did not know it cannot be programmed with USB. I searched a lot and found stm32f1init which uses arduino to send USART commands to the target board. I did the wiring as in comments and it only shows connecting.
Also found this reddit comment suggesting using arduino's FTDI directly. But STM32CubeProgrammer did not connect to the target board.
Im using Mac and that has far less tools.
I have two arduino boards and esp8266 board. Is it possible to use any of these to burn a usb bootloader into the stm32f1 chip?
Is there a way to just check if the bluepill board is in good condition?


texts: Driving a Sainsmart Relay using Raspberry Pi

texts:
I am actually a software engineer and not really familiar with wiring. I've been playing around with a Raspberry Pi Model B, and am looking to hook up a 2 PRONG Extension Cable to a Sainsmart 8 Channel Solid State Relay.

I am driving the GPIO pins from RPIO (Python). What I want to do is hook up a basic night light as the first channel output from the SSR and control it from GPIO pin 17. The problem is, I can't even get this to work. I am able to get the LED to light up pretty easily, but there seems to be no output. I've tried driving the relay on a HIGH and LOW signal, but no dice.

My wiring diagram is shown below... Apologies for it being very rudimentary... Any ideas what may be wrong? Is my relay bad?

Also note, I've several mechanical relays too and they all seem to do the same thing.

Also, I've been told that the GROUND side of a 2 PRONG cable is the side where the insulation has labeling. I'm assuming the GROUND part of the 2 prong cable is plugged into the top part of the output channel of the relay and VCC on the bottom. Can someone confirm with me?

I've also tried this with an Arduino, and it doesn't seem to work either. Sorry for the convoluted post, but this has been driving me nuts for the past couple of weeks!

EDIT: The LED on the board does turn on, but I haven't had luck powering something separate off from the port. And yes, I have tried powering it from a separate 5V supply.


texts: Voltage on the Serial Link and Parallel Resistor Value

texts:
This question is related to the previous question that I had over here
I found the serializer that I am using. It is over here
From the above serializer datasheet, on page 9, I found that the maximum differential output voltage on the pins OUT+ and OUT- are 0.61V
And the offset voltage maximum value is 1.56V.
So, in this case, the average voltage on the OUT+ and OUT- lines would be 1.56V + (0.61/2) = 1.865V, right?
Is my calculation correct?
And 2nd question, in the deserializer datasheet application diagram over here on page 74,
what is the purpose of the 49.9K resistor on the IN+ and IN- pins of the deserializer? Isn't it supposed to be 50ohms each for the parallel termination purpose? Why 49.9k instead of 50ohms? Can someone clarify?


texts: Software Serial alternative with AVR (Two Serial/UART ports in atmega328p)

texts:
Arduino pins can be used as UART using the library SoftwareSerial.h Is there any alternative for AVR?

I need more than one serial port on a ATmega328P, but i don't use arduino.

SoftwareSerial.h is tied to Arduino.h and Arduino pins. I do not use Arduino, i use avr-gcc with atmega328p and atmega8.


texts: I want to handle the voltage and current spikes from inductive load of 220V AC ceiling fan

texts: I am trying to regulate speed of 220V ceiling fan from Arduino but unable to handle the reverse voltage and current though I am applying the flyback diode across inductive load.


texts: Flashing STM32F030 via uart bootloader under linux

texts:
I'm going to evaluate STM32F030 microcontrollers (ARM) for replacement in one measuring device - and ordered a few already. Meanwhile I'm trying to collect info on how to work with them.

Currently I'm seeking for ways to flash them under Ubuntu - I want some console tool working via UART and built-in bootloader. I've found what seems to be an instruction with using OpenOCD, but I would be glad to hear about other utilities.

I need not debugging features, just to be able to flash a hex file to, probably, about a hundred devices... So the simpler - the better!


texts:
I am making a robot which can follow lines, avoid obstacles and follow arrows. I wrote code for line following and arrow following but I don't know how to implement interrupts with more than two priority levels. Can anyone tell me how to use interrupts for more than two priority levels?

Source code -

unsigned short current_duty, old_duty, current_duty1, old_duty1;

void InitMain() {
  ANSEL  = 0;                         // Configure AN pins as digital
  ANSELH = 0;
  C1ON_bit = 0;                       // Disable comparators
  C2ON_bit = 0;

  PORTA = 255;
  TRISA = 255;                        // configure PORTA pins as input
  PORTB = 0;                          // set PORTB to 0
  TRISB = 0;                          // designate PORTB pins as output
  PORTC = 0;                          // set PORTC to 0
  TRISC = 0;                          // designate PORTC pins as output
  PORTD = 0;                          // set PORTC to 0
  TRISD = 0;                          // designate PORTC pins as output
  PWM1_Init(5000);                    // Initialize PWM1 module at 5KHz
  PWM2_Init(5000);                    // Initialize PWM2 module at 5KHz
}

void main() {
  InitMain();
  current_duty  = 255;                 // initial value for current_duty
  current_duty1 = 255;                 // initial value for current_duty1

  PWM1_Start();                        // start PWM1
  PWM2_Start();                        // start PWM2
  PWM1_Set_Duty(current_duty);         // Set current duty for PWM1
  PWM2_Set_Duty(current_duty1);        // Set current duty for PWM2

  while (1) {                          // endless loop

  PORTD.F4=1;
  PORTD.F5=0;
  PORTD.F6=1;
  PORTD.F7=0;

    if (PORTB.F1==1) {                 // turn L  moter L pwm1
      PWM1_Set_Duty(50);
      PWM2_Set_Duty(175);
      delay_ms(500);
      PWM1_Set_Duty(150);
      PWM2_Set_Duty(150);
     }

     if (PORTB.F3==1) {                    // turn R  moter L pwm1
      PWM1_Set_Duty(175);
      PWM2_Set_Duty(50);
      delay_ms(500);
      PWM1_Set_Duty(150);
      PWM2_Set_Duty(150);
     }

     if (PORTB.F2==1 &&  PORTB.F3==1) {                    // turn R  moter L pwm1
      PWM1_Set_Duty(175);
      PWM2_Set_Duty(25);
      delay_ms(500);
      PWM1_Set_Duty(150);
      PWM2_Set_Duty(150);
     }

     if (PORTB.F2==1 &&  PORTB.F1==1) {                    // turn R  moter L pwm1
      PWM1_Set_Duty(25);
      PWM2_Set_Duty(175);
      delay_ms(500);
      PWM1_Set_Duty(150);
      PWM2_Set_Duty(150);
     }
  }
}


texts:
Suppose you have a circuit

,you are told that the voltage at point 2 relative to point 1 is -90V, the voltage across R2 is -30V and V0 is 200V.

What is the meaning of voltage at 2 relative to 1? Does it mean the potential difference between 2 and 1 as in (voltage at point 2) - (voltage at point 1) or is it vice versa?

Does voltage at a point relative to another mean a voltage drop between those two? And what roles do the negative voltages at either points play?


texts:
Could anyone suggest what's the best way to design DC-30Mhz LNA, any references?

My goal is to have ~10-15dB amplification with as low as possible noise. Both transistor based and IC-based variants are considered.

I've seen that MMIC's for higher frequencies have noise figure down to 0.7-1dB, but none of these LNA's could work below 50-100Mhz. MMIC's which can work down to DC magically have noise figure of 3-4dB.

Is it possible to achieve such low noise at low frequencies?

Ideally this amplifier will be before RTLSDR+Up Converter and narrow bandpass filter.


texts: If I need to generate power at a specified frequency, then I need to make sure that the rotor of the generator rotates at a specified speed (rpm). But when I am rotating it with steam or water how do I control this speed? It seems to me that the mechanical forces that rotate the generator somehow has to balance to achieve this. How exactly is this done?


texts: What are the types of devices that should use analog ground?

texts:
As the title says, what are the components that require a separation from the digital ground?
For example, currently, I have a PCB where the microcontroller is powered and grounded to analog ground and this has no effect on the performance of the analog components.
Could someone example what are the effects, some use cases and how to avoid ground loops?


texts: Minimal redistributable coregen output for command-line rebuilds

texts:
I'm building an SoC with my own soft-core, and I want people to be able to easily rebuild it using Xilinx webpack command-line tools.  I'm using coregen's Clock Wizard to create a clock module, but coregen's output doesn't appear to be redistributable (the resulting verilog source claims to be confidential and proprietary information of Xilinx, who reserves all rights and doesn't specifically grant the right to redistribute AFAICT).

Is there a command-line/Makefile recipe somewhere for getting similar output from coregen that I can redistribute to my users?

http://github.com/atgreen/moxie-cores , btw.


texts:
I am trying to build a dual slope ADC by designing the op-amp in transistor level.I am getting an exponential output. I would like to know how to get a linear output in the integrator?[![First image is the output, 2nd graph is the input signal][2]][2]

simulate this circuit – Schematic created using CircuitLab


texts:
I want to to shift  a signal which is varying from 1.2 to 3.3 volts ( a shifted square wave) to some other ground. I don't how to do this.
Frequency of this signal is 10 kHz with duty cycle around 10-60%.
And signals should be galvanic isolated.


texts:
I want to make a project to protect each individual cells of 16 series battery pack. I have read some data sheets of battery protection IC's such as BQ29209DRBR,S-8261,AP9281 etc. None of them clearly explain If those IC can be used in series. In my humble opinion ,if voltage difference will stay same ,there will be no problem.
But I need to take thought from professionals. Here is How I think of connecting them

Sorry for my ugly schematic :)

Here is some more datasheets that I think It may work R5432,BQ2947


texts:
I am reading the reference manual page 75 that shows the flash memory organization of STM32F4 MCUs. There is an OTP area of 528 Bytes in it as shown in the image:

Is it possible to write on this OTP area at run-time under user program control or is it writable at the chip-flash time only? I have tried to search this detail in the document but i cannot find it.


texts: How to find the clock speed my fpga runs in XPS or EDK?

texts: I created a custom ip and added it to my design. I want to find out the speed of the clock. Is there any menu/option to find out in Xillinx platform studio or EDK?


texts: Increasing loss of cables to attain dynamic range

texts:
RF newbie here. Trying to learn about cables and losses and how they contribute to dynamic range.

I'm creating a shielding effectiveness system for enclosures with a 120dB dynamic range using signal generators, power amplifiers, transmitter and receiver antennas (such as 12" loop, biconical, dipole, log periodic and gain horn antenna for different frequency ranges) pre-amplifier and spectrum analyzer. The frequency range tested is 9kHz to 40GHz.

Thus, is it acceptable to use a long cable to increase loss in order to attain a dynamic range of 120dB, since the gain of the system is relatively higher? For example, the DANL of the spectrum analyzer is -130dB for 9kHz, hence by theoretical calculation and working backwards by taking into account gain of amplifier, antennas and pre amp, I am trying to figure out the cable length between each instrument in order meet the DR.

Also, would it make more sense to use different coax cables for different bands of frequency such as upto 18GHz, 26GHz and 40GHz when designing the system for each frequency band? Or would a 40GHz low loss coax cable meet the needs of the system all the way from 9kHz to 40GHz? However, the attenuation of the 40GHz cable at 9KHz is almost negligible which makes it hard to attain the desired dynamic range.

Any advice on cable lengths and losses would be appreciated as currently I'm working on determining the length of the cable from signal generator to amplifier, amplifier to tx antenna, rx antenna to pre amp and pre amp to spectrum analyzer in order to achieve a DR of 120dB for various frequencies between 9kHz to 40GHz.


texts: 12 V input on 3.3 V GPIO, TVS pulled down or Schottky pull up?

texts:
I am building my own PLC that has to accept permanent inputs of up to 30 V DC into a STM32F with 3.3 V inputs.

The switched input will have to work with 8-30 V, but 90% of the time the input voltage will be fixed at 12 V or 24 V. Inputs will only ever be switches such as limit switches, so I am not bothered about detecting inputs less than 8 V or inputs from sensors, etc., I'm also not worried about speed as realistically the fastest the switches will move is every 1 s; I just need to be sure that my microcontroller is protected.

I want a universal circuit I can use in multiple products/projects of similar types so component count, cost and PCB space has to be at a minimum so I don't really want to use optocouplers.

Two electronic engineers have recommended the following, but I'm not too sure what way is best:

Should I use the top one or the bottom one? Any why?


texts: CD4011 Oscillator Square Wave Output Fed to Transistor Audio Amplifier; Volume Control Question

texts:
I built an audio frequency square wave oscillator using 3 gates on a CD4011 quad NAND gate IC. I then fed the output of the oscillator (pin 11) to a very basic "push-pull" transistor amplifier on the same breadboard. The output of the amplifier was then fed to a 2" speaker. The 9 volts of power to the circuit is from a regulated, work bench power supply.

Here is the schematic:

The circuit actually works pretty well. I measured the square wave out and it is about 8 volts peak to peak.

The sound from the speaker can be made fairly loud.

The 100K potentiometer, VR1, configured as a variable resistor, is used to vary the frequency out. I find I get a range of about 100 Hz to about 2,000 Hz.

The other potentiometer, P1, a 10K pot, is used on the input of the audio amplifier as a volume control.

Here is my problem: With an input signal of 8 volts, peak to peak, being fed to the amplifier, the sound is annoyingly loud. Hence the addition of the 10K pot on the input to the amplifier. The problem is that, with a 10K pot on the amplifier's input, only the very end of the travel of the wiper of the pot actually changes the volume. For most of the travel of the pot, the volume remains very loud. If I use a smaller value pot, the pot, itself, changes the output frequency of the oscillator. I guess this is because the small value pot is a like a "load" on the output of the CD4011 (pin 11)?

Is there a way to wire a pot, or another sort of volume control, so that the entire rotation of the pot's shaft affects the volume?

I wish I could measure or calculate the input impedance of the audio amplifier. Is there a way to do that?

* Update of March 24, 2019 *

Thanks for the helpful answers!

Here is the new version of the circuit schematic that shows the improvements to the circuit:

The improvements are:

1)  The schematic is now drawn with the CD4011 shown conceptually as 4 NAND gates rather than as a physical 14 pin DIP.

2)  The the fourth gate of the CD4011 IC, (inputs on pins 8 and 9, and output on pin 10), is now used as a "buffer" to isolate the oscillator, itself (the other three gates on the IC), from the amplifier that the square wave output of the osillator (pin 10) is fed to.

3)  R3 has been increased from 27K to 390K.  This helps keep the amplifier from being overloaded by the oscillator's output.

4)  The volume control pot, P1, has been reduced to 1K.

I will continue to play with the circuit, but it is a lot more functional now thanks to the helpful advice in this forum!

* Update Number 2 of March 24, 2019 *

OK, here is an even better version of the circuit.  See the new schematic:

Per the suggestion of a person in a forum on another website, I added R7 in series with the potentiometer (P1) volume control.  In addition, I changed the value of R3 to 100K instead of 390K.  Finally, I changed the pot back to a 10K pot instead of a 1K pot.

Adding the resistor in series with the pot lets me dramatically reduce the maximum voltage that the pot (used as a voltage divider) will send to the amplifier.  This lets me use more of the rotation of the shaft of the pot so it seems more like a real "volume control".

I found that the maximum total volume possible was too low using the 390K resistor for R3.  It was too loud using a 27K resistor for R3.  Using a 100K resistor is about right.

So, in effect, I am using R3 to set the maximum volume level to something that is loud but not annoying.  I am using the pot, P1, and the series resistor, R7, to force the pot to use most (about 75 percent) of its travel before reaching that maximum volume level.

Gracias to everyone!  Any ideas on how to further improve the circuit are welcomed!


texts:
I want to get power consumption results for my design which is written in VHDL using value change dump (VCD) file. I tried Xilinx power tool and Cadence power tools. What I observe is that if I simulate it for longer time (larger VCD file) I have more power consumption. If I simulate it for shorter time (smaller VCD file ), I get less power consumption.

Suppose the complete operation for the design only takes 10 ns, which kind of measurement is more accurate and why? Should I only simulate it for 10 ns or should I simulate it for like 1 ms to get the power results?


texts: Running AC solenoid vibration pump with DC voltage

texts:
Ulka e series solenoid vibration pump works with Ac voltage directly connected to main power.
They are rated at 220, 110, 24 voltage 50-60 Hz.
These pumps use an internal diode for removing half cycle of AC voltage.
The manufacturer specification does not determine the voltage as pure sine ac voltage.

Full specification of Ulka e series vibration pumps : http://ulka-ceme.co.uk/Ulka_E_Models.html

The question is that can these kind of pumps be running with square wave DC voltage controlled with pwm at 50-60 Hz without problem?
Will it damage the pump ? or reduce its lifetime?


texts: Designing from low-voltage 3-phase motor driver for more powerfull BLDC motor

texts:
I am starting to work on undergraduate project to build electric skateboard. Main thing
I will foucus on, will be ESC (electric speed controler) made for a motor 190KV (motor spec.).
I got micro-controller STM32F401 Nucleo and expansion board Nucleo low-voltage 3-phase motor driver STSPIN230. But here I got questions. This expansion board got low voltage range between 1.8 to 10v, but BLDC motor will be powered by 24 voltage battery supply. My main idea is to program a low-voltage 3-phase driver and at the outputs(U,V,W) design a circuit
which can boost power to my motor.

1.)Is this possible to build a circuit with 6 MOS-FETs at the end of low-volage Nucleo drive to boost output power and current for BLDC motor?

2.)Can this board make a output torque for low speeds?

3.) How hard is to design a smooth operation ESC that will speed smoothly and not have jerky brakes?

My main consern will be at the end, this ESC will power motor which will push heavy load (human 80 kg) down the road. I am trying to come close to a VESC product speciffically made for electric boards. A size of my ESC is not limited.


texts: Circuit with a MCP9700 temp sensor - What this capacitor is used for?

texts:
I have built a circuit that uses a MCP9700 to read the temperature as explained here.

This is the circuit schema:

I understand that C2 is used as a decoupling capacitor to clean up the noise (datasheet). However, I am not sure about C1. Is it a decoupling capacitor as well? I did the experiment without C1 and the temperature reading was not significantly affected.


texts: MATLAB - Allowing only numeric input using Exception Handling

texts:
I am trying to handle exceptions gracefully such that when a user enters a character, when a number is expected, he is notified with a custom warning/message.

I know that the try, catch has the following syntax:

try
   statements
catch exception
   statements
end

I have been trying something like this, to no avail:

number = input('Enter number');
try
    assert(isnumeric(number));
catch ME
    warning('NOT A NUMBER');
end

I do not understand why the above code fails since assert if it is false, displays the error message 'Assertion Failed'.

I know that using try and catch is a bit of a sledgehammer approach, but I would like to understand how to implement the above functionality. Any tips would be appreciated.


texts:
I have two circuits and want to on/off the supply of other circuit supply with one. I don't want to use a relay because of the dimension. What can I use for this implementation such as a mosfet, optocoupler or ssr? Other circuit needs around 3A.

simulate this circuit – Schematic created using CircuitLab


texts:
Using pic16f690 with xc8, I can't figure out how to set external osc with quartz crystal.

I have set :

#define FOSC_XT

Is that enough? Because I don't think it actually does something, I took out the xtal and the circuit still performs.

My configs:

#pragma config WDTE = OFF       // Watchdog Timer Enable bit (WDT disabled and can be enabled by SWDTEN bit of the WDTCON register)
#pragma config PWRTE = OFF      // Power-up Timer Enable bit (PWRT disabled)
#pragma config MCLRE = ON       // MCLR Pin Function Select bit (MCLR pin function is MCLR)
#pragma config CP = OFF         // Code Protection bit (Program memory code protection is disabled)
#pragma config CPD = OFF        // Data Code Protection bit (Data memory code protection is disabled)
#pragma config BOREN = ON       // Brown-out Reset Selection bits (BOR enabled)
#pragma config IESO = OFF       // Internal External Switchover bit (Internal External Switchover mode is disabled)
#pragma config FCMEN = ON       // Fail-Safe Clock Monitor Enabled bit (Fail-Safe Clock Monitor is enabled)

 #define FOSC_XT

EDIT: Tried:

config FOSC = HS  //8MHZ
config FOSC = XT

Same results-when taking out the xtal the circuit runs as usual, or even starts without it. (At the speed of internal osc of 8mhz.)


texts: Clarification about FCC exemption for subassemblies

texts:
please kindly help me understand the "subassembly" exemption of the Part 15 certification requirements regarding intentional radiators.  I want to produce and sell a MCU board which includes wireless communication features built-in.  Obviously this board must be incorporated with other circuitry in a final product/system by the purchaser, in order to make a working product, so my product is not a "final product".

Does this qualify as a "subassembly" and thus would be exempt from FCC certification requirements, or does the fact that it is an intentional radiator nullify the "subassembly" aspect?

Thank you.


texts: The problem about active low ,and how can i know it from the waveform

texts:
This picture is the simulation of D-flip flop with both active low reset and set,and i know active low means when the signal is 0 ,it means on .but how do i know it is active low from this picture?

Q and Q_bar is always 1.8 when set and reset is 0?so for this active low reset and set,if you feed reset and set low signal,the D-flip flop can't operate normally;but for active high reset and set,it can operate normally.Is my thinking correct?


texts: Gyro vs accelerometer for rotational acceleration

texts: For the same price chip, which will be more accurate to measure rotational acceleration: a gyroscope, or an accelerometer 10cm away from the pivot point?


texts:
2 phase dc motor 2.8 A per phase, I want to use a 48VDC single phase power supply to power the motor, what current rating should I have for the power supply?
Motor Spec (STP-MTR-23055): https://cdn.automationdirect.com/static/specs/surestepmotors.pdf


texts:
module dFlipFlop(
    input clk,
    input d,
    output q
    );
wire w1,w2,q_n;

assign w1 = ~(d & clk);
assign w2 = ~(~d & clk);

assign q = ~(w1 & q_n);
assign q_n = ~(w2 & q);

endmodule

will this module work as a D flip flop on my fpga? Any suggestions? I dont currently have my FPGA, but im trying to figure out if this design is worthy or not.


texts: DIY current sensor to arduino not working

texts:
I'm trying to build an energy monitoring device following this guide

http://openenergymonitor.org/emon/buildingblocks/how-to-build-an-arduino-energy-monitor-measuring-current-only

i hooked up the ct to a wire but doesn't seem to work.

I'm just hoping someone can find something wrong based on the picture...


texts:
I have a circuit running an ESP-12 at 3.3v DC that I would like to power with a doorbell transformer that will deliver between 8 and 24v AC. I was wondering what would be the best way to do that.

I'm currently powering the circuit with a 5V DC adapter and a HT7333 LDO (datasheet) to convert it to 3.3v.

I was thinking that I could use a bridge rectifier like the MB6S (datasheet) to turn AC into DC, and then use an LDO to convert to 3.3V.

The HT7333 has a maximum input voltage of 12v, so I will be in trouble when I use a 24v bell transformer, but there are LDO's that should fit the bill and which have the same footprint, like these.

I was wondering if there's anything else I would need to do to make this work? or if there are better solutions than the way I'm going?


texts: LM2577 5V Boost Circuit does not boost voltage

texts:
I have built a 3.7 - 5V boost circuit using the LM2577-ADJ Step-Up voltage regulator.

Below is a copy of the schematic.

I have followed the datasheet (p2) and have calculated Vout as follows:

Vout = 1.23(1+R1/R2)

with values chose for R1 & R2 as:

Vout = 5.05V =1.23(1+5600/1800)

However I have constructed this circuit and with an input voltage of 3.84V (provided by a single cell LiPo) I have an output voltage of 3.56V

Below is a picture of my board layout:

Any help on this would be great, i've checked all the connections for shorts/blown components and I am a little bit stuck.

Cheers


texts: PWM Fan Controller for heat exchanger with timed defrost cycle

texts:
I am building my own heat exchange ventilator and trying to figure out the best control board options.
The first part is simple. I want to enter custom parameters for fan speed based on a temperature probe's values. I need to be able to customize the temperatures.
The second (and more complex part) is a defrost cycle. Triggered by a temperature reading of 23*F or below, the defrost cycle would run for 10 mins as follows:
Fan 1 off
Fan 2 100%
After 10 mins, the program would return to the normal temperature based fan speeds.
After 50 mins of this cycle, the temp probe checks again for 23*F or below reading, either triggering or bypassing the second (defrost) cycle depending on reading.
I was planning to use PWM computer fans (4 pin).
What would be the most user friendly controller for someone with very little programming knowledge?
One option I was considering was using a series of 12v timers and small dedicated PC fan temperature controllers (like this)? This would be a very clunky solution, but would avoid getting in too deep with programming.
Thank you very much for the help and let me know where I can clarify further!


texts:
I have DIMM sockets too close together to put caps just outside their edges.

And places they can fit are technically too far away.

Can you safely put 0402 caps in the places under the socket, where they can fit?

That'll mean between pins.

Notice each FPGA has 4 dimm sockets, 2 above and 2 below That combination is replicated 6 times on the PCB.

So it's not allowed to put the caps just above the dimms, since that becomes just below on the next replication.

They'd need to go between pins on the bottom.

Will I get grief from the board house?

I'd love to change to 0201, but we're still being told to avoid those.


texts: Binary Manipulation in arduino with 74HC595

texts:
I'm doing practice of bit manipulation in arduino with a 74HC595 shift register. I would like to create an algorithm that allows the binary digit to perform this way:

1 0 0 0 0 0 0 1
0 1 0 0 0 0 1 0
0 0 1 0 0 1 0 0

.

.

.

1 0 0 0 0 0 0 1

How can I perform this type of shifting? I don't have any fluency thinking this type of operation, I have only performed a circular shift with "an algorithm" like:

myByte = myByte*128 + myByte/2

But I don't know how to perform the output that I showed.

How can I do this? Thanks

Update1:

This is how is wired the circuit

and this is the code that I use to perform a circular shift.

int latchPin = 11;
int clockPin = 9;
int dataPin = 12;
int dt = 800;

byte myByte = 0b00000001; //in BIN

void setup() {
Serial.begin(9600);
pinMode(latchPin,OUTPUT);
pinMode(dataPin,OUTPUT);
pinMode(clockPin,OUTPUT);
}

//circular shift to the left
void loop() {
digitalWrite(latchPin,LOW);
shiftOut(dataPin,clockPin,LSBFIRST,myByte);
digitalWrite(latchPin,HIGH);

Serial.print("BIN: ");
Serial.print(myByte,BIN);
Serial.print(" --> ");
Serial.print("HEX: ");
Serial.print(myByte,HEX);
Serial.print(" --> ");
Serial.print("DEC: ");
Serial.println(myByte,DEC);
myByte = myByte/128 + myByte*2;    //shift by left //using MSBFIRST
delay(dt);
}


texts: How does the RTC of a STM32L0 keep the time accurately when using the LSI as the clock source?

texts:
I am working on an application that must keep track of time (using a RTC), and will be uploaded on a STM32L052K8.
When I was making my hardware I just assumed that I will use the low speed internal (LSI) clock of the MCU. However, now that I am writing the code I saw something that really worries me.
According to the datasheet of the MCU the LSI oscillator characteristics are:

If this is indeed the case then does that mean that my time base clock will be anywhere between 26kHz and 56kHz? If this is the case, then the RTC is completely useless. If this is not the case then how does ST manage to get the a high accuracy RTC which runs on such an oscillator? Also according to the datasheet the nominal frequency of the LSI oscillator is 38kHz, but according to STM32CubeMX it is 37kHz as seen in this picture below.

What is the nominal frequency I should assume?
I really hope this has some solution with an acceptable accuracy (even +/- 1% is enough for me).


texts: Oscilloscope with FFT or a Spectrum Analyzer?

texts:
Could someone explain to me please which applications demand one or the other and why? As far as I have read it's all about the 'dB'; is that true? And why?

At first I can see Digital Storage Oscilloscopes (DSO) with FFT function and Spectrum Analyzers (SA) as being the same thing...they will get a signal from the Time Domain, and convert it to the Frequency Domain and we can check all the harmonics and frequency components of a signal and analyze it in a whole new way.......But since DSOs usually are much cheaper than SA, I keep wondering what functionalities the SA will offer that a DSO can't. Is it about precision, speed of calculation (my DSO FFT is really slow), bandwidth (cheap DSOs usually go only up to 100MHz), or does it just depend on the models and not on being a DSO or a SA? Is there more that I don't know about and you can tell me?


texts: MCP23S17 - do I have to use both Chip Select and Hardware Addressing?

texts:
I've used MCP23S17 before. 6 of it and I just used Chip Select. Hardware address pins all 0.
https://ww1.microchip.com/downloads/en/DeviceDoc/20001952C.pdf
In datasheet, hardware addressing can be used to connect 8 of it in a bus. No problem.
Now, I have another project that will require 12 of MCP23S17. I plan to use Chip Select again.
What would you do?


texts: Charging lead acid batteries in parallel?

texts: I recently got my hands on eight 12V 9AH lead acid batteries. Could I simply place them in parallel and charge them with a battery tender without any special measures? Are there any risks involved? Could it damage the batteries?