texts: What is the process behind the forming of a low voltage electrical arc?

texts:
I am trying to understand the exact process undertaken when forming a low voltage high current electrical arc, such as in a welding scenario.
My understanding at present is that without a high voltage, the oppositely charged electrode and cathode first have to touch. Once they are separated, the large contact area briefly becomes a small contact area, where the high current is forced into a narrow strand of wire or work piece. This area then undergoes ohmic heating, and melts/vaporises which leaves a gap between the electrode and cathode, which an arc is formed across.
What I don't understand is how the above process allows the air gap to becomes sufficiently ionised that it becomes conductive. Is the heat emitted by the melting wire sufficient to ionise the air, or perhaps the air does not become ionised by the gas from the melting electrode is itself ionised and the conductive path.
Thank you for reading this!


texts:
I have a 36V cordless lawnmower whose charger has died. A replacement charger costs $120 (!), which makes it not worth buying. The charger is 36V 800ma.
I can buy a charger for an eBike that is rated at 36V 2A for $20. I am comfortable swapping the plug from the dead charger to the replacement one.
The insides of the mower don't seem to have any regulating circuitry. The mower batteries are lead acid.
How likely would I be to have problems if I buy the replacement charger, swap the plugs and try using it? I'm not worried about long term problems - I'll probably dump the mower if I can't make it work - but I don't want to do anything dangerous.


texts: Analog to digital conversion: are natural number values possible with an amplifier?

texts:
I drew this circuit up for a project in Multisim.

The inputs for V1 are -0.25 to 0.25, and the outputs are 0v to 10v.

When -0.25v is inputted the output should equal 0v.
But its giving me an output that's close to zero instead, like -19mv.

Question: Is it possible to get the output the the exact natural(positive whole number) values?

Any help will be greatly appreciated.

circuit design of two designs

simulated circuit

simulated circuit of just the summing amplifier.


texts: What do you keep in mind while branding your PCBs? Design/professional appearance

texts:
I've just completed my first PCB and it's safe and well designed.

Now I want to put a vector image on the board with my brand's name with it. I was wondering how can I do this, so the art looks great.

Surely there's a way things are cut that matter quite a bit in the detailing when it comes out.

Is there someone who has done this frequently and has a checklist of things they keep in mind? I appreciate any feedback towards this.


texts: What is the Thevenin equivalent of this low-pass filter?

texts:
I am trying to calculate the Thevenin equivalent circuit of this low pass filter however, I have never done it with an AC input and am getting very confused.
$$R = 100\Omega ; C = 2\mu F$$
$$Vin = 2sin(2\pi*40*t) + 3sin(2\pi*142*t) + sin(2\pi*400*t)$$

Where the Thevenin circuit looks like this:

To find Rth
To find Rth, I have short circuited the voltage source in order to find the equivalent resistance. The resistor R and the capacitor C are in parallel, therefore;
$$Rth = R//C = \frac{R}{1+j\omega C}$$
Question: The Rth is in terms of w but the input signal has multiple frequencies, so how do I find the overall Rth?
To find Vth
I have found the transfer function which looks like this:
$$\frac{Vout}{Vin} = \frac{1}{1+j\omega RC} = \frac{1}{1+j\omega 100*2*10^{-6}}$$
Question: How do I find the overall Vth when there are three separate sin signals?


texts: How to properly store big values in parallel SRAM

texts:
For a project I need to determine the frequency and phase-shift of up to 16 channels. The frequency range is 0 to 3 kHz and the signalform is square.

My first idea was to use the following circuit to save the signals into a memory IC (SRAM):

(CTR = 16 Bit Address Counter, TMR = 21/32 Bit Timer)

The input channels IN are sampled on each positive CLK cycle.
If an edge occurred, the address counter is incremented and the WR (Write Enable) bit is set.

Then on the negative CLK cycle the SRAM is going to be active and saves the data if the WR bit was set.

The timer TMR is always incremented on each positive CLK cycle.

The sampling frequency (CLK) should be 20Mhz and the measurement period is 100ms:

Gives a 2'000'000 max. value for the timer: I need at least 21 bits to store the timer value:

21 Bits (timer) + 16 Bits (channels) = 37 Bits

But the data bus of the SRAM is only 32 bits wide so I need at least two write cycles to accomplish my task. I don't want to decrease sampling frequency because of the needed accuracy. So that is not an option.

I'm not exactly sure of how I can accomplish the two write cycles except to increase the SRAM write frequency to something ridiculous like 80 MHz. Another idea of mine was to simply just use two SRAMs instead of one, but this seems terrible inefficient.

So it all boils down to the following two questions:

Is a CPLD capable of doing such high-speed logic? (80MHz and up) I have the fear I will experience clock-skew inside the CPLD: I can't test a CPLD because I don't have the adequate equipment to generate such high-speed signals.
Is this circuit / idea even feasible or already too ''complex''? Are there easier solutions to my problem?


texts: Tips for using a switching regulator on a board where EMI must be kept to a minimum

texts:
I'm designing a circuit using a switching regulator but the overall design cannot have EMI.

I know that I need to add some sort of filters.  How would I determine which filters to add? Are there any specific types of components that will make the filters easier to design or allow them to offer superior EMI suppression?  Can I use multiple filters to further reduce EMI?


texts:
Compiling an existing PIC32 project using the v2.00 C compiler produces a continual watchdog reset. This problem does not appear using the previous v1.12 compiler. Changing the watchdog postscaler value (up to 1048 seconds) has no effect. The watchdog reset occurs almost immediately after startup, definitely not enough time for the timer to expire. Disabling the watchdog allows the code to run as expected.

There was a change to the startup code in v2.00, but I am not using any custom startup code to my knowledge. Could there be a problem with the timer used by the watchdog not being enabled correctly? Where should I look to try and debug this issue?

MORE INFO

The reset occurs when I clear the watchdog timer. If I use

WDTCONSET = 0x01;
// or
WDTCONbits.WDTCLR = 1;
// or
ClrWdt();

The reset will occur.

If I don't reset the watchdog timer (let the timer expire), I get a reset after the time specified by the postscalar, as expected.


texts: Sharp sensor not working with 9 V Battery

texts:
I am working on a project that uses Sharp IR sensor, an ADC, 8051 micro controller and an LCD Module. the Sharp Sensor is giving correct readings only when its power supply comes from Arduino and the rest of the circuit works on a separate battery. I tried to connect a separate 9 V battery with 5 V regulator to the sensor, also tried giving the sensor power supply from USB ASP Programmer but both results in incorrect readings that vary too little between 1.1 - 1.3 V regardless of the distance to object.

Note: Arduino is also connected to laptop with an USB. U3 is the distance sensor that works great if given power by Arduino


texts:
I'm trying to model a differential digital signal going through 4000 feet of twisted shielded pair.  The nominal impedance is 120 ohms and capacitance per foot is 14.6 pF.

For 1000 feet I calculated the inductance should be .0002 H and 14600 pF.  I broke the model up into 4 segments.  Each one with 14600 pf cap, and .0001 Henries on each wire.  I put four of these together with a 120 ohm resistor termination.

The results look close but not exactly what I see in reality.  The pulse width is really wide compared to what it should be and the output is ringing more than it should.

How many segments is enough to break 4000 feet into?  10? 100?  Is there anything else I can do differently?


texts: Command Solid State Relay using NPN transistor 2N2222

texts:
I'm trying to command a Solid State Relay with the HV1 pin, I can't connect it directly(HV1 to CH1) due to the fact that the impedance on that pin is too low and I only obtain 2.8V when connected.

So, I'm trying to use an NPN transistor(Q1). However, being inexperienced with tranistors I'm not sure that my schematic is correct(probably not).

Can you give me some hints on how to choose the resistor's value, or what should I change to make it work? Thank you!

This question comes after this question (Bidirectional Logic Translator translates to 2.8V instead of ~5)
(The "Switch" is actually the SSR)

CH1 is the command pin of the SSR

simulate this circuit – Schematic created using CircuitLab


texts: Automotive reverse current and transient protection

texts:
Adding reverse polarity and reverse current protection to an automotive circuit seems a bit challenging, especially when driving loads in the 10A range (e.g. seat heater). Diodes on the power line would present too much loss and heat in this case.
After having spent quite a lot of time studying solutions for this task I came up with this circuit:

simulate this circuit – Schematic created using CircuitLab
As of my understanding, this circuit would function as follows:

D1 & D2 are TVS diodes to suppress load dumps in both directions with min. breakdown at 25.7V and max. breakdown at 48.3V (considering standard pulses)
M1 is supplying power to the downstream circuits, that is supposed to serve as reverse battery protection as well. R1 & D3 should keep Vgs at a safe level of 10V. As soon as the internal diode of M1 starts to conduct, R1 & D3 can turn M1 fully on, eliminating further internal diode loss. R2 should stabilize Vgs.
D4 is supposed to handle negative transients. As per my understanding, it takes some time for M1 to turn off in case of a negative transient, during which a large amount of current is allowed to pass backwards along M1 and downstream circuits. The idea is to let D4 direct away most of the current during this short period, leaving only a safe portion to downstream circuits to handle.

Constrained VCC should be thus between:

max. 48.3V (D2 TVS diode breakdown voltage)
min. approx. -0.4V (D4 Schottky diode forward voltage drop)

Are my assumptions correct, is this circuit working this way? Did I miss something?
I know there are specifically designed parts for this task, but unfortunately they're not available in my area.


texts:
Why do they tell that

  • Burst length should be 10 cycles/burst or longer. After each burst
  which is between 10 cycles and 70 cycles a gap time of at least 14
  cycles is necessary

whereas I see only 7 in the 600us bursts of their time diagram

And what is the "carrier frequency" (30kHz)? I think infrared light frequency is measured in terahertz? Are those 7 pulses in the 600us bursts in the diagram are periods when LED emits light with gaps imbetween? How actually I supposed to communicate over the carrier frequency?

Why do they tell that 30 pulses, f = 30 kHz, T = 10 ms in the following Figure 1

My computation is that if every pulse takes 1/30k sec then 30 pulses take T = 1 ms. Furthermore, I see on this diagram that reception terminates (V_O goes high) even though transmitter is still bubbling. Can it predict the future?

update Also, the upper part of the second diagram (Figure 1) says that 10 led pulses is optimal for reception but bottom clarifies that receiver recognizes the burst that is between 7 and 15 LED pulses. That is, it is guaraneteed to receive bursts only when they are 15 LED pulses or longer. How can I use the optimal 10-pulse bursts then?


texts:
I'm extremely new to electrical engineering, and I was experimenting with diodes in series. I soldered six 1N4007 diodes together, and I connected them to a DC power supply (RSR ET122) with a constant current of 2 amps, and variable voltage up to 12 volts. I am attempting to use the principle that an applied current greater than the rated current will heat up a diode to implement the circuit as a source of thermal energy. When I used the DC power supply on the series circuit the diodes don't change temperature.

How can I change the circuit or the current to effectively heat up the diodes based on their current rating?


texts: An old man I used to work with had a set. Two old handsets with two conductors coming from them. It had a 9v power supply, I believe. We used it to trace existing interlock wires, hundreds in one conduit. Just hook one lead from each phone to a common wire, usually the ground, and try the others till I heard the ol man whistling. How can I make a set of these. Other designs require the base or four conductors. Thx


texts: About Transistor Amplification (Voltage amplification in CB mode)

texts:
https://youtu.be/Qwd-5H24tRo

Based on that video, I learned that in CB mode Transistors amplify the i/p voltage, based on the fact that the BC junction is reverse biased and so that the o/p dynamic resistance is higher than the i/p one. So, as the I stays almost the same, o/p V is greater than i/p V.

Now, I am thinking, as Vo = IcRL and it doesn't depend on the o/p dynamic resistance of the reverse BC junction, then what if I choose RL less than Ri(i.e i/p dynamic forward bias resistance of EB junction), how can then the transistor amplify even though being in active region (I've biased the Transistor to be working in the active region, just changed the value of RL)?

Update: I tried to find the error myself, but, here I seem to find two different expressions for the same Vo! Vo=IcRL is dependent on RL only whereas by internal resistance consideration, I found another expression for Vo which is independent of RL! (About the image)


texts:
I want to have a capacitor to keep my RPI from "powerdown" when the supply goes from the 5v Samsung charger to the power bank. I have the redundancy diodes and the primary output is Samsung charger. When I switch from battery to mains the RPI does not shutdown. When from mains to battery it shut down.
Now I tried wiring 4x 330uf cap in series for total 990uf across the rpi vin/gnd (I do not know if I connect the charge resistor correct - in series with the load/rpi). The rpi did not boot.
I do have some 2200uf caps also.


texts: how to design circuit of high side MOSFET switching with bootstraping and mosfet driver ic?

texts: Hey im starting to learn about MOSFETs at my university classes, but Im having trouble trying to design a circuit for a buck boost converter for a MPPT solar charge controller. The part pushing me down is the high side switching, I kinda understand the boostrap operation with the capacitor and the diode, but dont know how to integrated with my MOSFET driver ( TC4420 ). I know that boostraping is needed because I will be using an N channel MOSFET, but I dont have a clue how the circuit might look I know is probably really simple but im kinda stuck. If someone can show me how the circuit can be I would really appreciate. Im using TC4420 mosfet ic.


texts: Do front and back porches for digtal video really matter?

texts:
I am developing an LCD controller, and some of the code for my (third-party) timing generator includes horizontal and vertical front/back porch and vsync/hsync pulse time information for a different LCD module.

The datasheet for the LCD I'm actually using has horizontal/vertical porch and pulse times, and these vary (in some cases substantially) from my third party code.

However, my understanding is that the porches, etc., really only matter for analog video, and that the data enable bit is the most important.

The sync pulses are where I'm a little hazy.

Is it likely to make any difference if I go back and edit the third-party timing generator code to use the same porch and pulse timings?


texts: Thevenin Equivalent circuit, concept question

texts:
I am looking at the circuit in: Apply Thevenin Theorem to a circuit with 2 sources?

The circuit and its equivalent have been given as follows in the thread:

Circuit:

Thevenin Equivalent:

Instead of v_test, I presume I can place a resistor, resistance 10, and the current across the resistors should be the same for both the original circuit and its equivalent.

For the first circuit, the current across the added resistor is: 0.96 A

For the equivalent circuit, the current across the added resistor is:
\begin{equation}
i = 6.4/(3.3333+10) = 0.48
\end{equation}

what is the issue here?


texts: Range of duty cycle ms to drive RC servo motor and transfer function

texts: I am using the ball and beam control system from Acrome robotics and I would like to identify the transfer function of the RC servo motor which translates motion to the system. First of all, I have asked the company for information about the model of the motor used but I have not received an answer. Is there any way to find out the milliseconds in order to put the servo at 0,90 degrees ? And if I collect the input data (ms of duty cycle) and output data (degrees), can I figure out the transfer function of the motor’s system ?


texts: Ive been trying to find a mathematical explanation on how a Synchronous Buck converter maintains continuous operation under ideal steady state conditions. I understand the underlying concept but i want to know how i can explain it mathematically (ideal case).


texts:
I just started learning NPN transistor and was trying to replicate Falstad - NPN sample in LTSpice. Somehow I get all base, collector and emitter current in the micro-Amp range while the sample shows current in the milli-Amp range. Since the circuit sample in Falstad does not resistor on either terminals (B, C, or E), I add a low resistance resistor to mimic a wire just for LTSpice to show current probe symbol and see the plot of current.

Could someone explain why am I getting this drastically different current even when I copy the same parameters in the sample, and explain what I did wrong?


texts: Can I run an ATmega on 3.3V with an external 16 MHz crystal?

texts: I have been told that is overclocking or it just will not work, but I want to be sure. And are there any real differences that would effect from this? Any tips and tricks will help, thanks!


texts: Luminous flux of 0603 and 1206 LEDs with the same color and current rating

texts:
I am looking at SMD leds, and it seems that same leds of same color in 0603 and 1206 cases, having same rated current and same angle of irradiation, show different light flux, 1206 being several times brighter.

What is the explanation for this? My task is to get maximal brightness out of bunch of blue SMD leds. 0603 are smaller and cheaper, so for the same money I can place 3x times more of them, while 1206 have higher rated mcd flux.... Hi-power 1-3W leds which are rated in lumens does not work for me, as I would need them on flexible PCB.

I am puzzled... Any info on that?


texts: Hall Effect Sensor to a +24VDC PLC Input

texts:
I have a square wave from a hall effect sensor giving between UL 7.7v-8.7v to UH 11.3v to 12.7v from a 13V Supply. I need to pass this into a logic input on a controller which is nominally 24vdc but operates at <5V Logic0 and > 15V Logic 1.
My square wave has a frequency of 100Hz.
I am not an electronic engineer and people tell me I need to use a zener diode or maybe a Schmitt trigger but I am at a loss.
Can anyone help please
Many thanks
Lee


texts: Synchronising GPIO transitions to an external clock

texts:
Currently, I am using an ADC with an external trigger with the caveat that the edge of the trigger must be within +/- 25ns of the ADC's clock (See Figure 3 of the datasheet).  The ADC's clock is available on a pin of the ADC.

In this case, the GPIO used to operate the trigger is not synchronized with the ADC clock and therefore synchronization is necessary. Apparently,  the best way to do this is with two cascading D flip-flops connected to the same clock in order to ensure that there is no race condition between the setup time and the clock pulse.

There appear to be some gotchas with this approach. Some sources recommend a delay between the two flip flops for added safety. Others say that "synchronization hardened" FFs are necessary.

So, what's the best way to solve this problem? Is there a ready-made logic family that will do the trick? Or a specific IC?


texts:
I have a problem with my servo motor. I connected a servo to the PWA connection of a PCA9685, but powered the motor externally. There's no problem with that and it works fine with some smaller servo motors. But when I connect the exact same thing to the servo motors I actually want to use, the MC-410, then it doesn't work. Or, should I say, it works very spontaneously. Meaning that the servo moves only sometimes and then for a while not anymore.
The problem can't be the servos, I tested them directly with the Pi and they work, just not in my setup.

The whole thing is controlled by a Rasperry Pi 3 B+, the servos are powered with 6V, 1A.

If you have any questions, please ask, I'm happy to explain further


texts: Altium: What stands for 'N' , 'M' and 'L' as a suffix for SOIC packages

texts:
I've noticed while using Altium that SOIC ICs have 3 different SOIC PCB layout to select from, they are named NSOBX_L, NSOBX_N and NSOBX_M (being X de number of pins). The difference I've noticed  is that the 'L' variant has smaller body size, and all of them have the same distance between pads but pad length varies through all of them. I know that when deciding which one to use the wise thing to do is checking if they fit the manufacture's recommended layout for the specific IC but I'd like to know anyway.

EDIT: I've checked the PCB layout and confirmed that lead pitch is 1.27 for all  of them. From the wikipedia link that Andy left in the comments I can tell that MSOIC is excluded, there's a chance that the 'N' SOIC variant stands for Narrow SOIC but still there are the other two left.


texts:
After long time investigation, I could not find proper information about "#define EEMEM   attribute((section('.eeprom')))" macro on eeprom.h header file.

I want to declare variable exactly at address 0x0010 on Atmega128 EEPROM. Because, when I use (example) "uint8_t EEMEM Variable = value", it saves value at 0x0000 address automatically, it is being deleted sometimes (I think there is some mistake on hardware.) I tried with different hardware, but same result.

In Codevision for AVR, you can use as: " eeprom unsigned char Variable@0x0010; " to declare variable at 0x0010 address of EEPROM.

My question: "Is there are any alternatives to daclare variable at 0x0010 address on AVRStudio 6?"


texts: Protecting AVR flash from reading through ISP?

texts:
I'm trying to protect whole flash from reading through ISP. It has bootloader, able to self program application section.

Setting lock byte to:

LB1/LB2 will not let user to use bootloader to upload new firmware.

BLB12/BLB11 and BLB01&BLB02 will not prevent reading flash through ISP, if I am not mistaken.

So there is no way to let user update firmware by custom bootloader and protect flash from reading at the same time?


texts: Is there an instrument to measure/uniquely identify gadget's RF signal strength

texts:
I'm not a technical person. Apologies for not being able to express myself clearly.

I have a base station(blackbox audience response system bought from manufacturer) used during events that transmits 2.4GHZ RF signals across the halls. (E.g Huge Convention Halls)

I want to measure the signal strength from this gadget at different parts of the hall where it is placed in order to see which area has weak signal.

However, in public places, there may be other RF signals from unknown devices.

Are there instruments that I can use to measure/uniquely identify the power/signal strength of my base station?

Thanks in advance!


texts: How to Capture Momentary Current Reading on a Multi-meter

texts:
I am attempting a circuit design that involves connecting to a DLSR camera PC port.  Newer digital cameras deliver very small amounts of current (mA) to their PC port during shutter release.  This very small current sets off the flash to any connected camera flash.  My circuit will connect a very old flash to this new digital camera.  Old flashes (Flash bulb flashes) are triggered by higher amperage amounts.  These higher amounts would fry the controller board on the digital camera.  Hence a circuit in between.

I need to understand exactly how many mA are sent to this port, when the camera’s shutter is triggered, but because the duration of the current is in the milli-second timeframe, I do not know how to use my multi-meter to capture a current this short in duration.


texts: How to find Vout for the following band pass filter

texts:
I have a problem finding the following Vout for this circuit.

Is it possible to just use the following formulas that i have shown. I am just unsure due to the resistors.

I assume that what i have done is wrong as i might need to take the other resistances for Req.

In short this question is asking:

1.How to find Vout and Vin

How to find the transfer function for the whole band pass filter


texts:
I'm trying to design some kind of backup battery charger - please see the image:

Normally, the DC supply is ON, and provides current for load and also charges the battery. Battery should be charged to 27V or more, and maximum charging current must be limited to 4 A (when battery is fully charged up the current should automatically decrease to 0).

When DC supply is turned OFF, the battery provides current for load instead, with maximum allowed current.

I'd like to ask You for any references, circuit ideas or even some keywords to look for on internet and other sources.

Thanks.


texts: Controlling high output LED's with a microcontroller

texts:
I'd like to build a circuit to precisely control the current through a couple of (LED and laser) diodes. I would like to minimize the number of components if possible. Power consumption is not a primary concern, so linear regulators and dissipating resistors are fine.

I am looking at a LM317-based circuit and this will serve fine for a constant or potentiometer-tuned current, but I want my current to be controllable by a microcontroller. How might I achieve this?

If it is possible to do this without an additional op-amp, BJT, or FET, please explain.... Actually, please explain no matter what. :)

Looking to drive LED's individually (or in series) at up to not much more than 1A. (Vf < 4V)


texts: Signal to noise in relationship with limit of detection and/or signal strength

texts:
I wonder about the following:
The limit of detection is given as being 3 sigma of the blank peak away from the blank signal (which is noise finally, I think?).
What struggles me is: In my head this is also very closely connected to SNR but I may confound them..  however, do the peak heights not play a role in this context? For example, the height of the signal can be arbitrary high or low, compared to the blank signal. Hence, one of them might overlap the other, then what?
My thoughts:
When the signal peak is so low that the blank signal will overlap it, it can't be 3 sigma apart from it. This is obvious. But the signal might be much lower in general.
So maybe my question isn't about LOD or SNR but about: When is my signal strong enough that I can say "There is a signal"?

On this link I found:

  The minimum detection limit is the concentration corresponding to a
  peak that can just be distinguished statistically from background
  fluctuations. This is generally taken to be a peak height equal to
  three times the standard deviation of the background count.

I think this explains it, doesn't it? So to conclude: The peak height has to be as high as 3 sigma of the blank measurement (noise)? When the signal is lower, it isn't the LOD.

I'm not sure whether the topic fits here as it also touches chemistry or physics but, finally, it is about to detect/separate signals so I think the electronics thread makes the most sense.


texts: I have been using PICs for years and am used to having a programmer like the PICKIT to program the chip with. I have a project now for which I think a Freescale micro might be a better choice. I have found there is a free version of Code Warrior, but I am not exactly sure how the programming of the chip works. What is the process of doing this?


texts: Interfacing LVDS to 1.2V IO Bank (e.g. POD12 or SSTL12)

texts:
I am currently working with an Arria 10 device (specifically a ReflexCES A10 SoM Indus module). The GPIO pins of the device are split into IO banks with specific VCCIO voltages controlling the banks.

We are quite tight for pins on the design we are working on, and on the SoM module pin headers there are a pair of differential IO pins that I would like to make use of for a pair of ~200MHz LVDS inputs. However, as they are on a bank which is shared with a DDR4 interface, the VCCIO is set to 1.2V. The Arria 10 doesn't support LVDS on a 1.2V IO Bank.

Having looked through the datasheets, the A10 devices support the following IO standards on a 1.2V bank: HSTL, SSTL-12, and POD12. Additionally as the pins are on a bank shared with a DDR4 controller, they can be configured for 48Ω or 120Ω calibrated termination resistor.

I've been unable to find a device which is designed for interfacing with any of the available standards by name using a DC coupled method - the LVDS lines are not scrambled so require DC coupling.

Upon further reading, it seems that POD12 (1.2V Pseudo Open Drain), the standard used by DDR4 controllers, actually seems to be relatively similar to CML in its termination scheme. Looking up some clock buffers, I find the Micrel/Microchip SY54016AR which is designed for re-driving 1.2V or 1.8V CML lines. Specifically it can take a DC coupled LVDS input, and convert it to a 1.2V CML line. The output can also be DC coupled using the following termination scheme:

Based on the Arria 10 Handbook, when operating as a POD-12 receiver, it is designed to use one of the following two termination schemes. The lower one uses on-chip calibrated terminations which can be configured for 48Ω±15%.

With a VCCIO of 1.2V, the two diagrams look to me to be compatible.

Furthermore, the re-driver has an eye voltage of 360mVpp up to 500MHz with common mode of ~0.6V. The Arria 10 requires >300mVpp swing, with a common mode of >0.2V.

So, my question is, will this work?

In order to test it we will have to spin a full PCB with assembly of some high density FMC connectors, so before going down that route, I'd like to get some confirmation that I'm not barking up the wrong tree.

Alternatively if you have any alternate/recommended approaches, those would be also welcome.


texts:
Is there a way to dim LEDs?

The idea is to run them in my car and have a dimming switch somewhere but I cannot find a suitable dimming switch and was hoping some one could recommend other methods of dimming LEDs.


texts: Generating 1 second with avr and timer 0 for Atmega32A

texts:
dears:
we have to Generate 1 second with atmega32A and mikrobasic software.
so I have configured timer 0 and avr with this way:

const _THRESHOLD = 250
TCCR0=0x04
TCNT0=0x06
OCR0=0x00
' // Timer(s)/Counter(s) Interrupt(s) initialization
TIMSK=0x01

and overflow function:

sub procedure Timer0Overflow_ISR iv IVT_ADDR_TIMER0_OVF
' // Reinitialize Timer 0 value
TCNT0=0x06
if (counter1 >= _THRESHOLD) then
counter1 = 0

so with TCCR0=0x04 WE USE 256 presqale with external clock 16MHz wich :

16MHz/256=62500

which means timer 0 clock is 1/62500=0.000016 Second
which TCNT0=0x06 timer 0 over flow clock is 256-6=250
which take 0.000016*250=0.004 Second for one overflow of timer 0 with TCNT0=0x06 .

so for creating 1 second, it needed to count timer0 overflow for 1/0.004=250 turn of timer0 overflow. the above codes are written based of this calcuation.
SO when we program this codes into atmega32A, for 5 minutes the clock is Lag for 5 seconds.

  Changes based of new comment.

  I have changed TCNT0=0x07 for 249 clock of timer0 and 1 clock for
  overloading ti,er values. but still counter lag for 5 second  at 5
  minutes .

please help me to correct my codes.

Thanks a lot.


texts: Dealing with the "overflow" of data in a ring buffer

texts:
So I have a ring buffer that's used inside the USART's ISR to stores the user input and upon receiving \r, it calls the application callback where I parse the elements into a local buffer between the head and tail indices, but I see the following issues:

the old data in the local buffer stays. So in case, the incoming data is shorter than the previous data, you'll see something like 'n','e','w','o','l','d'.

Determining the length of the new data would help cause then I could just take the substring of it but determining the length by subtracting the head index from the tail won't work in case there was a wraparound.
E.g:
Ring buffer size: 9
Head index: 7
Tail index: 1

you get 3 more new chars and the head index becomes 1. So computing the length by mere subtraction won't work.
tl;dr - the issue i'm trying to get around is being able to separate the new data from the old data in a local buffer (which contains the parsed data between the head and tail index). The same issue will occur if the user inputs more data than the length of the ring buffer i.e it would override the old data. But with index, even you have a large enough buffer, you'd still see the same issue eventually.


texts: Can I apply nodal analysis if the wire doesn't have a resistance?

texts:
simulate this circuit – Schematic created using CircuitLab

How do I apply it in the wire containing D4 and D3 if it doesn't have a resistance? The way I learned is: \$\frac{V-V_{D4}-V_{D3}}{R}\$ but in this case there is no resistance across \$V\$ and ground. Should I put \$R=0\$?


texts: Solving for voltage across resistor in mesh circuit

texts:
Hey all I am once again asking for help on circuit analysis,

Ive done mesh analysis and the results are
Ia = IR1 = 0.1641A,
Ib = IR4 = 7.33mA,
Ic = IR8 = -0.1089A,
Id = IR9 = -0.06373A,
now what i'm supposed to do next is find out the voltage across all the resistors, but Theres too many nodes so i'm unsure where to start, I know I can use ohm's law to find VR1 = 1.641V, VR4 = 0.2933v, VR8 = -8.717v and VR9 = -5.736v but the others I have no idea how to even start.
Any help would be greatly appreciated.


texts: Rail-to-rail oscillations in subtractor op amp circuit

texts:
simulate this circuit – Schematic created using CircuitLab

Just bumped into a problem. When I am trying to make a voltage subtractor based on AD8055 op Amplifier, I get rail-to-rail oscillations/noise one the output.

The signal is 0.5sin + 1.5V at 1MHz. I wish to shift down the signal to 0.5sin + 0.5.
Any ideas why I do not get a desired output?

Edit:


texts: directly charge a laptop battery / using laptop battery for projects

texts:
I've seen a couple similar questions, but nothing exact. I'd like to know how I can charge a laptop battery directly, meaning without the laptop. This would be a battery still intact, in good condition (not just a collection of cells).

I understand many laptop battery packs have circuitry built into them to protect from overcharging and over depleting. I don't know how advanced/accurate this would be, but it sounds promising at least.

Could it be as simple as buying a laptop battery like this and a physical wall charger like this and physically connecting the positive and negative connections, or would it involve building a controller circuit to sit in between them?

The goal in this case is to be able to utilize a small form-factor laptop battery pack as part of a portable ham radio setup. I could have one or more charged batteries available to me, swap them out as needed, and then charge them directly. I just don't want to buy a laptop to charge them.


texts: How to make MCLRE in CONFIG3 word work in PIC18F using MPLABX XC8

texts:
I am trying to start with PIC18 microcontrollers with a PIC18F14K50.
I am using XC8 compiler and MPLABX IDE v1.2 and I have re-checked the selected device in the project configuration.

For now, I am trying to set the configuration words. I am aware of the file below which contains the information on the configuration words.

  .../Microchip/xc8/v1.00/docs/pic18_chipinfo.html

When I set the MCLRE to OFF, thus trying to disable MCLR function and enable RA3 as digital input, it seems like it doesn't set it to OFF. It stays ON all the time.

I am testing this on "Labcenter Proteus ISIS v7.9 SP1" and "mikroProg Suite for PIC by mikroElektronika". Both say that MCLRE is ON, so I cannot change this bit. Also, I cannot change the HFOFST bit which is in the same register with MCLRE in CONFIG 3. However I can set up other configuration bits.

Below is my code. Can this be a bug?

#include <xc.h> // Include the header file needed by the compiler
// CONFIG 1
#pragma config CPUDIV = NOCLKDIV    // No CPU System Clock divide
#pragma config IESO = ON            // Oscillator Switchover mode enabled
#pragma config PLLEN = ON           // Oscillator multiplied by 4
#pragma config FOSC = HS            // HS oscillator
#pragma config FCMEN = ON           // Fail-Safe Clock Monitor enabled
#pragma config PCLKEN = ON          // Primary clock enabled
// CONFIG 2
#pragma config BOREN = ON           // Brown-out Reset enabled and controlled by software (SBOREN is enabled)
#pragma config BORV = 30            // Brown-out Reset Voltage set to 3.0 V nominal
#pragma config PWRTEN = ON          // Power-up Timer Enabled
#pragma config WDTPS = 1            // Watchdog Timer Postscale Select bits 1:1
#pragma config WDTEN = OFF          // WDT is controlled by SWDTEN bit of the WDTCON register
// CONFIG 3
#pragma config MCLRE = OFF          // RA3 input pin enabled; MCLR disabled
#pragma config HFOFST = OFF         // The system clock is held off until the HFINTOSC is stable.
// CONFIG 4
#pragma config DEBUG = OFF          // Background debugger disabled, RA0 and RA1 configured as general purpose I/O pins
#pragma config STVREN = ON          // Stack full/underflow will cause Reset
#pragma config XINST = OFF          // Instruction set extension and Indexed Addressing mode disabled (Legacy mode)
#pragma config BBSIZ = OFF          // 1kW boot block size
#pragma config LVP = OFF            // Single-Supply ICSP disabled
// CONFIG 5
#pragma config CP0 = ON             // Block 0 code-protected
#pragma config CP1 = ON             // Block 1 code-protected
#pragma config CPD = OFF            // Data EEPROM not code-protected
#pragma config CPB = OFF            // Boot block not code-protected
// CONFIG 6
#pragma config WRT0 = OFF           // Block 0 not write-protected
#pragma config WRT1 = OFF           // Block 1 not write-protected
#pragma config WRTB = OFF           // Boot block not write-protected
#pragma config WRTC = OFF           // Configuration registers not write-protected
#pragma config WRTD = OFF           // Data EEPROM not write-protected
// CONFIG 7
#pragma config EBTR0 = OFF          // Block 0 not protected from table reads executed in other blocks
#pragma config EBTR1 = OFF          // Block 1 not protected from table reads executed in other blocks
#pragma config EBTRB = OFF          // Boot block not protected from table reads executed in other blocks

void main(void)
{
    TRISC = 0x20; // RC0: Out / RC1: Out / RC2: Out / RC3: Out / RC4: Out / RC5: In / RC6: Out / RC7: Out
    LATC = 0; // Clear PORTC output latch.
    ANSEL = 0; // All analog inputs are disabled and made digital.
    ANSELH = 0;

    while (1)
    {
    }
}


texts: How to calculate current drawn by microchips, transistors and diodes?

texts: So far, I've dealt with only devices like resistors, capacitors and inductors. Calculating the current drawn by these devices is very simply by using the formulas I read in my Physics textbook (e.g. V = IR, Q = CV etc). But how do we calculate the current in case of a connected diode, LED, transistor or a microchip. Sometimes some examples refer to a forward voltage or some direct value of current and do the calculation, which confuses me completely. How can I find out these values of  voltage and currents so I can solve the circuits just like I was able to when I dealt with circuits with R, L and C (individual or in combination).


texts: ATTiny85 not working after burning bootloader

texts:
I am having a problem with my ATTiny85. I should mention I use Arduino as an ISP to program it.

My ATTiny worked fine until I decided that I need to step up the clock speed from 1MHz to 20MHz so I selected ATTiny85 at 20MHz from the Boards menu and then clicked on Tools>Burn Bootloader. But that was stupid, since now my ATTiny doesn't work at all. I cannot upload sketches on it and if I try I get this message:

  avrdude: Yikes!  Invalid device signature. Double check connections and try again, or use -F to override this check.

So my question to you would be, is there a way to reset what I have done? Or even better, to make it work at 20MHz?


texts: LiPo-management and alarm-clock sharing on same MCU

texts:
I am working on a wake-up light alarm clock project using a small 3.7V LiPo battery (5V USB charger).

I am considering using a microcontroller to do the alarm clock function rather than a dedicated alarm clock IC as the LED need a PWM to turn on gradually in about 15-30 mins.

Reading this article I found that battery management can also be done with a MCU rather than a dedicated IC.

Can I share the MCU to do both alarm clock and battery management functions? I don't see any reason why not, but as battery management is something subtle I wonder.
Do you have reference design for LiPo management for a specific MCU that could match my need? In the article they say most MCU suppliers published notes or evaluation designs for that function but can't find such and had no luck yet contacting MCU manufacturers. As LiPo management seem to require extra care in the code I would rather use reference design.


texts: Why the sum of the responses of s and s increase with 20dB per decade or 40dB per decade?

texts: I am not sure by how much will the response of the function H(s) = s^2 increase?


texts:
I have a project where for the prototype, I'm using some off-the-shelf components, namely drone cameras and DVR boards installed in a car.

The DVR board has a status LED and a momentary switch which I would like to relocate to a more accessible location on the dash in a 3D printed enclosure.

Is it recommended or even possible to piggyback 24 AWG wire to the solder joints on the PCB for these components to extend them to the dash-mounted control panel?

For the switch, would the second remote switch still work or would the PCB mounted switch interfere with its operation?

Also, in the same vein, I need to relocate the MicroSD reader from the PCB to the dash mounted control panel. I'm probably going to need to extend it about 2m. Is that going to affect my write speeds?

Obviously, my knowledge of electrical engineering is very basic so all suggestions and help are appreciated.

(Link)


texts:
Please could someone explain how to compute the impedance with which to determine the frequency characteristics of the high-pass input filter in the following circuit?

My question is prompted by an example from Horowitz and Hill 2nd ed. 2.05. I think this question could be formulated with a simpler circuit, but I don't know how to simplify it while retaining the essential aspects. The sizing of the components is explained as follows:

Choose the output voltage for a steady input voltage in order to maximize the range that won't be subject to clipping, i.e. 7.5v (half-way between the min/max of 0v/15v).
Assuming a quiescent current of 1mA, we can calculate R3 to be 7.5k using Ohm's law.
Now we choose R1 and R2 by deducing that the base voltage for Q1 will be 8.1v (since it is 7.5v + 0.6v drop from base to emitter). Also, we assume the gain of the transistor to be at least 100 meaning that its input impedance is at least 750k, and choose the parallel resistance of R1 and R2 to be at most a tenth of this, i.e. 75k. The two conditions give 130k and 150k for R1 and R2 respectively.
Now we choose C1. This is supposed to be an audio device so we want to retain frequencies above 20Hz. The -3db point for the RC filter will be at 20Hz = 1/(2*piRC1), which we can use to find C1 given R.

My question is about the determination of R. We assume that the load driven by this emitter follower is high compared with the emitter resistor and therefore determine that the input impedance of the transistor will be gain*7.5k = 750k.

So R is the parallel resistance of R1, R2 and 750k, which works out at roughly 63k and C1 should be at least 0.15uF (a larger value is chosen in practice to reduce attenuation, and we get the final 0.5uF).

My question then, is why is R determined as the parallel combination of R1, R2, and the transistor input impedance? Or indeed, more simply, why is the input impedance of the voltage divider R1 and R2 equal to their resistance in parallel? -They are not in parallel, they are in series between +15v and 0v.


texts: Is switching over 70A of AC power with a relay common, or should I directly switch power with a manual switch?


texts: Build an 8-digit display using Seven-segment Display and 74HC138

texts:
I am trying to create an 8 digit, 7 segment display using an Arduino, 2 4-digit displays and an 74HC138 demux. The 4 displays each have 12 pins: 4 common cathodes, 7 segments and one dot. I thought I would use 8 of the Arduino's digital pins and wire them to the segment and dot pins on the displays, and then use the of the Arduino's digital outputs to control the 74HC138 demux and use that to select the subdisplay. The IC outputs a LOW on the output pin, and so I need to wire a transistor so that it connects the common cathode to ground only when the base current is LOW. Is that correct? How would I wire the components to do that and what transistor do you recommend for this? Should I add any resistors between Arduino's +5V and the LED displays or the IC output and the base terminal of the transistor?

The pinouts for the IC

The 4-digit LED display


texts: Low battery indicator doesn't work on batteries but works with trim

texts:
I made low battery indicator with LM393. But circuit doesn't work as it should.
If I connect 100k trim to IN- of 1st op amp which imitate "battery voltage", op amp turns red LED on when voltage from 100k trim is less than threshold voltage.
But if I connect + pole from battery to IN- then circuit doesn't work. Why?
Everything is connected on same ground potantial. I use 5V from step-up converter for LM393 VCC.


texts:
I have a x-ray machine rated at 8KW, 230V AC. I have a 5KW UPS with 100Ah battery bank. Obviously I cannot use this as a power source for the x-ray machine. Therefore I am planning for a 10KW UPS. The UPS needs to supply power to the x-ray machine at 230V AC only when the x-rays are produced, i.e a maximum of 5 sec at a time. The UPS will normally require 96V DC battery bank. My question is can I replace the battery bank of the 10KW UPS with a capacitor bank ? If yes what should be the rating of the capacitor bank?
The idea is to charge the capacitor bank with my existing 5KW UPS and then use it to power the 10KW UPS.
If this is possible I can get rid of 8 nos of 12v DC batteries required for the new 10KW UPS.
Any suggestions?


texts: How to make repeatable Op-amp amplifier circuit

texts:
I did a simple op-amp based 100X gain single ended circuit. I tried to order 100 IC's and manufactured them. But found that out of 100 only 60 devices have same and expected baseline. What could be the reason for this variation and how do i improve my yield? (PS: I use TLV9061) All resistors used are SMD type 0603 1% tolerance resistors.
Also sensor that i would be using is a capacitive load of 220pF, will this op-amp be good for that.

Test case:
If the vsensor is not connected, the output of the op amp should be 0.33 as an ideal condition. I considered OK range as 0.3 to 0.4 . Only 60 of them were marked OK. Rest all are out of range, may be 0.2V, 3.0V, 2.08V etc


texts: Questions about sensing pulse current and driving a logic MOSFET in a circuit

texts:
This question is about a personal project and related to my previous question but focusing on different issues or questions. By increasing the shunt resistor from 1 mOhm to 330 mOhm I wanted to avoid using a special amplifier like in my previous question.

A uC's PWM output will control 2A to 6A current through a heating-wire and since the resistance might change, the current value roughly will be fed back to ADC of the uC for regulation ect. The circuit will be soldered on a perfboard.

For minimalism, I decided to use a single-supply op amp and low-side sensing to avoid common-mode-voltage related issues.

For clarity I will write down the questions one by one in detail:

1-) This article examines the use of op amp, difference-amplifier and instrumentation amplifier for this purpose. What I first understand is, if I use a difference-amplifier or an instrumentation amplifier I have to use a split-supply(or maybe some reference voltage techniques which will reduce the range I don't know actually). Since the only option left for me is an op amp option, the article mentions the following issue for that case:

  The drawbacks to low-side sensing are disturbances to the system
  load’s ground potential and the inability to detect load shorts.
  Figure 2 depicts a typical low-side sensing scenario.

And below Rp or Vp illustrates this:

My question is, in my application would that be an issue as well? I mean I can live with 100mA error. I couldn't find a topology where I can use a single difference amplifier with a single-supply. Is that possible? Or how can I minimise the error introduced by ground?

2-) I used LM358 as an active filter with unity gain and it follows another LM358 as an amplifier with a gain of two(to match 0 to 5V range to the ADC).

Green is the swept PWM voltage across Rsense; blue is the output of the active filter with LM358 and the red is the final output. Is LM358 proper for this application? And is 0.33 Ohm shunt resistor is high enough?

3-) Basically the question is do I need a gate driver for this MOSFET(for power dissipation concerns)? According to the data sheet this is a logic MOSFET. But still some in my previous question told me I still need a driver for since the MOSFET has capacitance which will drive excessive current.

But one of the commentators told me that I need a special driver such as this one. But the rest didn't find it as an issue. So I'm confused how to drive this MOSFET properly. Here is what LTspice shows the MOSFET's power at %95 PWM:

Edit:


texts:
After searching for a BJT solution, I decided to replace my Darlington pair with a single MOSFET transistor. I have a microcontroller with max I/O pin current of 4 mA at 3.3 V. I have a FQP30N06L MOSFET with 2.5 V VGS threshold, and if i look at the graphs:

Figure 1 shows me that on VGS 3 V and ID of 0.5 A, I have really low VDS, does it matter and is it fine?
Figure 2 shows on the minimum ID of 1 A, the VGS is 2, which is good for me, right?
Figure 3 shows RDS of 30-40 mΩ, what does that mean? I read it is important info, but could not understand how I can use that.
I could not find how much minimum current I need to pull on the gate, and with that info I want to calculate the resistor value on the base.

I know it is a lot of questions, but I want to make sure I am not going to burn my microcontroller or my door lock.


texts: Can't use util/delay.h on c++ in Avrstudio v6

texts:
I'm just new with microcontrollers and I'm hoping someone could help me understand this. I'm using an AVRStudio 6 and an AVRDragon. Watched some tutorials on basic programming.

Here's the code:

#include <util/delay.h>
int main(void) {
    _delay_ms(30);
}

What I can't understand is when I made a new avrgcc c project it works well. But as a c++ fan, I made a new project using avrgcc c++ and the code won't work.
The error message is as follows:

2. 'fabs' was not declared in this scope
3. 'ceil' was not declared in this scope
4. 'fabs' was not declared in this scope
5. 'ceil' was no declared in this scope

I tried those codes  in my avrsudio v6 by avrgcc c++ program and the warning #1 goes away but the other 4 warnings are still there? If I use avrgcc c there are no problems.
What must I do so I could do this with avrgcc c++?
Can anyone help me understands whats going on?
Thanks a lot guys!


texts: Should a fuse with the correct amps, but is physically too small, still power my stereo unit?

texts:
I'm not sure if I'm asking the right kind of question for this site. But if someone could help me, I'd be grateful:

I blew a 125V 2.5A fuse in my home stereo head unit. I couldn't find that fuse at any stores nearby, but I was told 250V 2.5A would work just fine. I bought those but when I went to install it, I noticed I bought 3/4" size but need 1" size.

Even though it's too small to fit in the fuse clamp, I figured it would still work if I drop it in there and have the metal touching on both sides. My stereo powers up like it's working again, but now I get no sound; just humming from my speakers. I've checked all the speaker wires, they look fine.

Is this because the fuse is too small, or does it sound like i have another problem?


texts:
Basically, I began modding my Soundcraft Ghost sound board and wanted to put in a different op-amp that would sound more "colored" in the preamp stage. From everything I've read, the OPA2134 is the most suitable substitute, being the most stable and making a significant difference in the sound.

I was told to expect oscillations because the higher slew rates will increase the bandwidth and expose weaknesses in the surrounding circuit, and supposedly how to fix the oscillations. I'm not sure I would describe what happened from just plugging it in as oscillations, but rather as instability. Lots of pops and noises while adjusting the pot which is VR1 on the schematic, and when depressing the "Line" switch, fully opening VR1 caused intense feedback and extremely loud output with absolutely no signal connected. The phantom power also went absolutely nuts compared to the non-modified channels when it was switched on. When it is at a VR1 setting that it working properly and stably, there is less noise than with the TL072's, the same volume signal, and it sounds overall more musical to my ears (and yes I blind A-B tested this with several people).

First I tried connecting the voltage rails to ground via ceramic .1 uF caps, while keeping the leads as short as humanly possible and literally nothing happened. I was told for certain this would work. Then I was told I need to bypass the biasing voltage divider with .1 uF caps. That was equally effective. Another person told me that I needed to change the bias on the non-inverted input by adjusting the voltage divider so I hooked up a pot, and the most I could do was eliminate the gain pot scratchiness, while the phantom power and line input problem remained. I tried a .01 uF cap on the voltage rails of the op-amp and interestingly the line-input problem disappeared but gain pot scratchiness remained. Combining the changed voltage divider with the .01 uF cap made them both not work! The phantom power problem never went away no matter what I tried.

So I went to looking at why these things were supposedly working for others (it did cross my mind that maybe they were choosing to live with the instability and working around it) but not me. Something I noticed was that the 33 pf feedback caps were not on my channel revision, and neither was C6! The rest of the circuit is basically identical to the schematic.

My question is, why did people make these suggestions to me to begin with? What are they theoretically supposed to do? What is good practice in preventing instability and oscillations and how can I apply it here? Is it really a good idea to simply attempt to limit the top end of the bandwidth or is that just avoiding the root of the problem?

Could my board's revision lacking the 33 pf feedback loop caps (C67, C68) and the C6 electrolytic be the reason why the proposed solutions to my problem aren't working?

Lastly, how am I supposed to interpret a feedback loop that heavily involves a transistor and gain pot linking two separate op-amps? It seems more complicated than most literature I've found on the subject of op-amps.


texts: Net connection is not showing in PCB view in Altium

texts:
I don't find why in PCB view, my component(highlighted) is not connected to chip whereas in schematic it is connected to the chip and there no error in the schematic.The highlighted cap(C307,100nF) is not showing any white line to the chip VDDC.

The VDDC is a pin which is visible on the IC.

Please find this unknown pin: pin Cxxx-x error while updating the schematic to PCB which I saw now.

Also, i find a small circle on each component. how can I remove them?

I am new to Altium. Hope to hear from you guys soon.


texts: What PWM Frequency should be used for a 12V DC Gear motor?

texts:
I have this 12V DC Gear motor, but I can't find much info about it online. The reason I have bought it was that I found this particular motor across several tutorials on how to build an RC car.

I will be using the L298N Dual H-Bridge Stepper Motor Driver to control four of these motors, and while I wait for it to arrive, I've started working on the software. After some research online, I have determined that the PWM frequency to be used varies depending on what motor/motor driver is being used.

That said, I would like to ask people who have used hardware similar to mine what PWM frequency should I use to use these motors optimally?

Thank you in advance.


texts:
On a USB 3 port win 10 latest Arduino IDE 1.8.13
I try to compile the webcam server example of an ESP32-Cam.
I'm using an FTDI232 programmer as in the picture below.
I checked everything connection is properly wired.

And I checked with 5v and 3v wiring schemes).
For 5v i used top left pin in the picture below of the esp32

I followed this tutorial : https://dronebotworkshop.com/esp32-cam-intro/
And tried to resolve it with https://randomnerdtutorials.com/esp32-troubleshooting-guide/ (but its not for this board)
My wiring is like :
The reset button lights up front led when i press it (i guess thats normal).
However i cannot upload code, it only has one reset button.
And i tried pressing it long and short from 1 sec to 20 sec (if that matters?).
However its not uploading when doing normal upload:
esptool.py v2.6
Serial port COM3
Connecting........_____....._____....._____....._____....._____....._____.....____

A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header
A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header

If i do "upload using programmer" (not sure if i have to do that, should I ?)
Then i get the error:
java.lang.NullPointerException
    at cc.arduino.packages.uploaders.SerialUploader.uploadUsingProgrammer(SerialUploader.java:295)
    at cc.arduino.packages.uploaders.SerialUploader.uploadUsingPreferences(SerialUploader.java:90)
    at cc.arduino.UploaderUtils.upload(UploaderUtils.java:77)
    at processing.app.SketchController.upload(SketchController.java:732)
    at processing.app.SketchController.exportApplet(SketchController.java:703)
    at processing.app.Editor$UploadHandler.run(Editor.java:2055)
    at java.lang.Thread.run(Thread.java:748)

Any ideas ?


texts: Connecting power supply outputs in parallel

texts: I would like to know if it is safe to connect in parallel the outputs of a power supply like this, and in case it is feasable, how to proceed.


texts: How can you make curved PLATED slot in Altium 17?

texts: I need to make a plated slot in Altium, but it needs to be CURVED, rather than straight. I can make non-plated curved cutout by drawing curved track with the needed thickness and then using Tools>Convert>Create Region/Cutout from selected primitives. But I cannot find a way to specify that this cutout should get plated.


texts:
What book would you recommend for someone who comes from a software background that is looking to become fluent in Arduino?

I'd prefer something that walks the reader through examples, from N00b to advanced.


texts: Can Solid State Relays be used "anywhere"?

texts:
With mechanical relays, they can be inserted anywhere in a circuit.

Can SSRs be used anywhere in a circuit or are there certain gotchas that exist ?

Consider this simple example where SW* is a SPST SSR with a on resistance of 3mOhm.
Can I expect the the resistors to be shorted (excluding the 3mOhm ) when the SSR fires ?

simulate this circuit – Schematic created using CircuitLab


texts: How to model transistor ATF 53189 in QUCS?

texts:
In my internship I have to create an amplifier with low noise, high impedance and that works in the 100 to 400MHz band.

While searching for a transistor, I found the ATF 53189 (datasheet), which seems to be suitable for my project. The problem is that I can’t design the model of this transistor in QUCS (Quite Universal Circuit Simulator). Instead, I'd have to model it with ADS (Advanced Design System). But my laboratory needs it with QUCS.

Below is the model image.

So my question is: Can I model the transistor ATF 53189 in QUCS? How?


texts: How to translate from data sheet to actual pin function (blank Atmel SAMD21)

texts:
I am looking for a way to actually read an Atmel processor (SAMD-21) pin setup; but I am not sure how do you actually get the right info from the data sheet.

I did read the pinout, which has names like PA00, PB03 and so on; reading in the multiplexed section, I see a table with each pin, but I can't get what it actually does. I was expecting something like "SPI MOSI" or "Serial TX" and such; instead the table has a ton of entry that does not look like anything that I recognize.

For example Pin 13 is PA08, as type it is mentioned as I2C, and the rest of the line has entry like

NMI  AIN[16]  X[0]  SERCOM0/Pad0  SERCOM2/Pad0  TCC0/WO[0]  TCC1/WO[2]  I2S/SD[1]

I did search in the section related to pinout, but there is only this table, which while it tell me if the pin is a I2C or SPI, it doesn't give me any context to translate in what I would see on a breakout board for example.

Is there a conversion table that show what these entry mean? I am a SW engineer, so this is my first attempt at reading a datasheet for a processor.

UPDATE:

Found some info online, after looking for SERCOM.

From my understanding, the SAMD21 has programmable pins, but there are some that are set as default for communication related to I2C, SPI and UART. These are under the name "SERCOM".

This show basically the default value for each pin, using an arduino zero board as reference

Pin     Default     SERCOM      SERCOM alt
-----------------------------------------
PA00    xtal                    SERCOM1.0
PA01    xtal                    SERCOM1.1
PB08                            SERCOM4.0
PB09                            SERCOM4.1
PA04                            SERCOM0.0
PA05                            SERCOM0.1
PA06                            SERCOM0.2
PA07                            SERCOM0.3
PA08                SERCOM0.0   SERCOM2.0
PA09                SERCOM0.1   SERCOM2.1
PA10                SERCOM0.2   SERCOM2.2
PA11                SERCOM0.3   SERCOM2.3
PB10    MOSI                    SERCOM4.2
PB11    SCK                     SERCOM4.3
PA12    MISO        SERCOM2.0   SERCOM4.0
PA13    EDBC        SERCOM2.1   SERCOM4.1
PA14                SERCOM2.2   SERCOM4.2
PA15                SERCOM2.3   SERCOM4.3
PA16                SERCOM1.0   SERCOM3.0
PA17                SERCOM1.1   SERCOM3.1
PA18                SERCOM1.2   SERCOM3.2
PA19                SERCOM1.3   SERCOM3.3
PA20                SERCOM5.2   SERCOM3.2
PA21                SERCOM5.3   SERCOM3.3
PA22    SDA         SERCOM3.0   SERCOM5.0
PA23    SCL         SERCOM3.1   SERCOM5.1
PA24    USB         SERCOM3.2   SERCOM5.2
PA25    USB         SERCOM3.3   SERCOM5.3
PB22    EDBG TX                 SERCOM5.2
PB23    EDBG RX                 SERCOM5.3
PA30    SWCLK                   SERCOM1.2
PA31    SWDIO                   SERCOM1.3
PB02                            SERCOM5.0
PB03    RX LED                  SERCOM5.1

So basically, you can set any of these pins if you need extra ports for I2C, SPI or UART.

Since I am using the bare SAMD21; I believe that the pins does not even have a default set. If anyone did start with a bare SAMD21, I would really appreciate some guidance about how did you set up the chip.

Datasheet link: http://www.atmel.com/Images/Atmel-42181-SAM-D21_Datasheet.pdf

Pinout : page 26
Muxing table: page 33 to 36


texts: How do i determine max voltage for a custom BLDC

texts: I would like to know the process that you would go through to determine the voltage rating on a BLDC. I imagine that it has something to do with how the coils are wrapped and the how many coils there are. Any further reading into this, or equations i can use would be appreciated.


texts: Is this a standard power connector? (from Victron Energy 12V battery charger)

texts:
I am trying to find out whether I can buy this connector.  I've browsed Victron Energy's manuals/specs and can find no mention of the connector name.
Spec sheet PDF
Note that one of the corners of the male plug prongs is squared off.


texts:
I want to develop an industrial board with Cortex-M7 board and i selected Atmel because of Atmel Studio looks very nice for coding. I developed some projects with Arduino. My questions :

ATSAME70Q21 has 114 I/O . Can i use all of these I/O as GPIO?
If answer of first question is "yes" then all of thee GPIO will be
interrupted IO?
I want to buy "SAM E70 Xplained Evaluation Kit" to start Atmel Studio
development case. Description of this kit says that kit includes
information about to built custom board. My biggest problem is building
custom board which i can use all power of this MCU. So i should trust to
this evaluation kit or somebody has any advice for building such board?
I read some informations about GPIO pin speed(operating frequency).
These pins work at same operating frequency as with MCU speed at
some MCUs and slower at some other MCUs. I couldn't see any information
for Atmel cortex-M7 MCUs. Is it very important property? What about this
property at ATSAME70Q21?

Building a custom board for ATSAME70Q21 is the most difficult step for me. I don't know how should i start. So especially i wait a solution for it.

Tthanks in advance.


texts: microcontroller programming vs object oriented programming

texts:
I have done some basic object oriented programming with C++ (creating a B-Tree, Hashing Algorithms, Double Linked Lists) and I have done small project in C (like making a scientific calculator etc.)

How different is hardware programming (specifically for micro controllers) from software/object oriented programming in terms of the mindset and "thinking" that the programmer has to have?

Is one usually considered harder than the other my most people?

With my background (as described above) would I need a lot of preparation for going into hardware programming or can I dive straight in without too much preparation?


texts: Issues with OpAmp gain and instrumentation amplifier (Packaged and designed)

texts:
simulate this circuit – Schematic created using CircuitLab

Currently I have the following configuration using the LM358 single rail supply OpAmp. Each individual resistor value has been checked and I am currently receiving both the 15V rail source and the V1 from the same power supply (With both having a common ground).

In simulation I am showing 12.16V output on VoutFinal, but when testing the circuit I am seeing the following results:

Input -> Output
.1V   -> 2.02V
.2V   -> 5.00V
.3    -> 7.82V

I'm confused, not only are these not the gain I should be getting but the outputs seem to get a different result as the input is changed. What do I seem to be missing?

On the topic of instrumentation amplifiers I had (Burned it unfortunately) and INA128P instrumentation op-amp which required dual rail supply. When I had hooked up the OpAmp to a power supply with dedicated + and - Voltage ports I was able to input .01V and get 1V output (So correctly obtaining the 100 gain of the opamp).

Then when I attempted to use an op amp with no dedicated + - voltage and instead tie - to GND (So then + port is outputting positive 15v) and then tie + to GND (So - port is outputting negative 15v). Not only were I not getting any good results but it messed up the chip.

What am I missing? My ultimate goal is to get a high gain (60-100) while reducing noise as much as possible and having a stable output which an instrumentation amplifier is ideal but I'm a bit lost.


texts:
I started to make my own eagle library with all basic parts like resistors, capacitors, inductors and so on...

I know there is a standard for electronic symbols but I couldn't find the dimensions of the symbols (for example the width and height of a resistor) (I'm talking about DIN here).

Does someone know where I can get that information?


texts: Automatic switching between external 5V and USB bus power supplies

texts:
I'm designing a USB device which can either be powered by USB or an external 5V power supply.

When an external 5V power supply is present, the device should be powered solely by this external supply. Otherwise, the device should be powered by the USB bus. In other words, the external supply should always be prioritized, regardless of voltage level compared to Vbus. This rules out solutions based on diode-ORing.

Furthermore, the device will potentially consume quite a bit of power (several amps), so a solution based on MOSFETs would be preferred. When drawing a lot of power, the external supply is required.

So far I've found only one IC which seems to do what I want, the LTC4417. However it's rather expensive and supports up to three supplies, which is more than I need. Does anyone know of other simpler (cheaper?) ICs?

I've come up with the circuit below which appears to work in simulation, but I'm not sure it will work in practice. For instance, is it possible to get an inrush current from Vbus to Vext during the transition period? Does anyone know of a simpler circuit to safely switch between the two power supplies?


texts: I have a access control system that applies 24vdc to a solenoid to unlock a door. The power supply is 24vdc 16a inrush, 1a constant. Due to the wire size and distance it doesn't always pull it completely in. Is there a capacitor circuit that could be built at the solenoid end that would "help" with the initial current inrush, then charge up again while the current is holding the solenoid open? Maybe grasping at straws, but this looks to be the site that would know which straw! Mainly looking to see if this is even possible before subsequently trying to figure out the how. Thanks!


texts: high frequency vs low frequency lock-in regarding signal to noise ratio

texts:
I understand that the lock-in technique came about in an effort to improve signal to noise ratio.

There are lock-in amplifiers operating in high and low frequency regimes.

In the context of signal to noise ratio, it seems what determines the noise portion is the bandwidth of your lock-in signal (since rms noise voltage at the output is proportional to the square root of the band width).

So, what are the benefits and downsides of running it at high frequencies vs low frequencies?


texts: How to syncronize two motors with one pot?

texts:
I am trying to synchronize two dc motors with their own controllers.  The controllers are name brand and use a 10k pot to control the speed.  I have a duel 10k pot and would like to be able to "trim" one of the motors to stay in sync when the speed is changed.
First, I tried adding a second 10k pot in series with one of the sides of the duel pot, one lead to the wiper, one to one side. That didnt seem to do anything. Then I wired the second pot in parallel with one leg of the duel pot using all three leads. This kinda worked, the two motors changed speeds together but if I synchronized them using the second pot then changed speeds for both motors with the duel pot the two motors were no longer in sync.
The purpose of all this is to run an accessory with a conveyor belt.  I would like the teeth of a gear like part to run at the same rate as the conveyor underneath it. I was going to do it mechanically using one motor but for a couple reasons it would be great to do it with two and not have to manually sync them every time the speed is changed.
Thanks in advance!
Philip


texts:
This is kind of theoretical question, but I hope that it will not bother anyone and it will not be reported or closed after a minute.

In all basic electrical literature there is always information about most important and dangerous things like neurological current flow effect, but there is not much details about other effects, only an information that other effects happen too.

I saw here few guys related with bioengineering and medical equipment, maybe they can share some advanced knowledge about this.

I want to ask what are current flow effects other than:

neurological effects that may stop heart
skin damage from heat

What else may happen? What is going on in body cell scale? Are there some cells vulnerable more than other? For example - blood cells contain iron - can some electrolysis happen there? Or in some other cells?


texts: Capacitance divider of Colpitts Oscillator

texts: For the following Colpitts Oscillator, Why does employing the capacitance divider up-converts the source impedance of transistor by a factor of (1+C2/C1)2


texts:
To reduce EMI the datasheet recommends using a LP filter as shown in:
http://ww1.microchip.com/downloads/en/DeviceDoc/39762f.pdf page 219, Figure 19-2.
The filter is made of 56pF capacitor and 120ohm ferrit.
Why is the 56pF capacitor placed directly in parallel with the TPOUT+/- pins?
I would have placed the ferrit bead in series with the TPOUT+ pin and the capacitor after the ferrit bead (and likewise with the TPOUT- pin).


texts: Is it possible to connect one electrical device to two electric sockets?

texts:
Let's assume I have an electrical device like a tv set connected to a power outlet and it is running. I want to switch the electrical connection to another socket without interrupting the tv show I am watching.

Could I clamp on a second power cord to the wires in the first one, plug the second cord into the second socket, and then pull the first plug?

What happens, if anything, if a device is plugged into two electical outlet sockets at the same time?

Does it make a difference for AC versus DC? Do the phases of AC have to be in tune? Does the voltage change (e.g. add up)?


texts: Switch to turn off motor and another to turn the motor on

texts:
I have a DC motor that turns a gear which then has an arm that will hit a switch which turns the motor off.

Is there a way for me to build this without using a microcontroller?

Like I start the motor with switch1 then the motor hits switch2 which then turns the motor off, so to activate it again I need to press switch1.


texts:
Some people online say that acute angles in trace routing will cause these problems:

"Acid Trap" - PCB etchant gets stuck in the corner, and eats away too much, causing open circuit
"Peelable" - Narrow strip of photoresist falls off the board before or while the etchant is applied, causing too much etching and thus open circuit

Some people online say these are real problems, others say they are old wives' tales.  Are they real or not? Or are they only real if you use a low-cost fab house that might use older processes?

Please avoid answers like "ask your fab house". I'm looking to learn in general, not just get one design out the door.


texts:
Specifically, I'm talking about this product here...

Brita Faucet Filter

It has an LED that blinks when the water is running. It blinks red, yellow, or green to indicate filter quality (maybe) - but it seems to have no power source. So, my specific question is what powers the LED? And, I would also like to know what it's measuring?

It is frustrating to Google this because people don't seem to care how things work, and the phrase is equal to "What does it do" and all I can find is "It shows you the water quality" - well, that's not how it works. Brita claims the filter lasts for 100 gallons, but I'm not sure about that, it seems as though the LED turns to red based on the amount of time, but to do that it would need a constant power supply and I don't see one.


texts: Need circuit for 12 volt 2 Amp step down power supply from 18 volt 1.5 Amp Input

texts:
I have a power supply which outputs 18v 1.5 amp. For the purpose of my project, I need a 12v 2 amp power supply. I was wondering, if I can make a simple buck converter to convert 18v 1.5amp DC to 12v 2amp DC. Any help is highly appreciated.

I searched Google and could only find 12-5v buck converter examples. I know my circuit will be similar but I am little worried about the values of the components specially the switching transistor (if used) and the capacitors. I am a beginner in DIY electronics. Please help.

In this regard, I must ask that, I had a 230v to 0-12v 2amp step-down transformer. I tried to utilize this transformer to make my 12v 2amp power supply. When I applied a full-wave bridge rectifier to the AC 12v output, my filter capacitor blown away. I tried with 2200uF 25v and 1000uF 50v capacitors. What is going wrong here - is the current too high for the capacitors? Also, if I remove the filter capacitor, the transformer shows 13v 3.5 amp in no-load condition - just attached to an multimeter. Is this expected?


texts: Writing MIPS assembly and machine code for instructions

texts:
I am continuing my practice with MIPS assembly and machine code. I am doing a problem that assumes the following:

• variables a-j are assigned temporary registers $0-$8.
• the base address of arrays A and D are in $9 and $10.
• if need register to store an intermediate result, use remaining temporary or saved registers or register $at.

$0 - a    $1 - b
$2 - c    $3 - d
$4 - e    $5 - f
$6 - g

These are the problems:

a) f = a - 20 + b + c - d;
b) D[i] = A[j] << 6;
c) f = g - A[D[5]]

This is my attempt:

a) addi $0, $0, 101100
   add $5, $1, $2
   add $5, $5, $0
   sub $5, $5, $3

As for b) and c), I am not too sure how to do start it. I have attempted to find examples online but haven't been able to and the examples I'm going off of aren't that great.

If anyone can check and see if there is any issues or if you have any advice/help, Id appreciate it Thank you.


texts:
I am trying to use PDV-P8103 photocell as a sensor for LCD dimming circuit. The application requirements are to have comfortable brightness level from almost total darkness up to direct sunlight.

The problem is that the cell swings between about 300 Ohm all the way to over 1M. Usual connection as part of voltage divider simply does not work, as depending on fixed resistor the ADC quickly saturates at either 0 or VCC.

Is there a simple way to squeeze dynamic range of a photocell into something useful for reading by ADC? Note, that the precision is not important for this application, only the ballpark ambient light assessment.

Here are some approaches I have considered:

Adding OP-Amp in attenuator configuration;
Powering the voltage divider from DAC output and use it to select range first before sampling ADC;
Giving up on full range and picking fixed resistor for dark conditions, since human eyes adapt to darkness much better than to bright light.

Neither of the above struck me as ideal solution, so any ideas are welcome.


texts: If a wire is insulated from arcing up to 10 kilovolts, is it insulated up to twice that much from corona discharge?  Because I’m imaging that for corona discharge to occur, the electricity has to flow outwards by the repulsion of like charge, so it would have to flow through two 10 kv wire insulation layers.  So one like charge would be pushed out through one direction while another like charge is pushed through the insulator in the opposite direction, making it as if the barrier was insulated to 20kv.


texts: Volt regulator for in the car to run a rasperry pi

texts:
So I have an raspberry pi (with alot of other stuff on it like a touchscreen and GPs module), but I use it in the car. It consumes alot of power and the default power supply which deliveres 2.4 amps isn't enough. So I was wondering if it is possible to make a power converter that converts 12V (10 amp) from the car, to 5V (high as possible amps) to run the pi. Now, Will this damage the pi? Or will the pi only take what it needs?

Now I have an schema, but I have no clue if the schema is correct, so here it is;

Also, I want to make a PC out of it, so here is that result:

If someone could help me out with this, that would be awesome!

I'm using eagle as drawing software. Could someone please help me?

Regards,

Robin


texts:
I want to read a 24 Vac signal coming from my old automatic gate with my Raspberry Pi. The signal tells me if the gate is OPEN->24 Vac or CLOSED->0 Vac. Raspberry Pi input are 3.3 Vdc tollerant. My first idea was to use a rectifier to get a DC signal and then use a voltage dividers to get the 3.3 Vdc. The second one was to use a octocoupler to achieve the same results. Has anyone any suggestion on what type of such devices should I use to achieve my goal?
Best regards
Ric


texts:
How can get input capture values from STM32F4 for measuring the duty cycles of the four different signal?

Here is one channel code:

uint32_t IC2Value,Frequency,miliseconds;
float DutyCycle;

static void TIM2_Config(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
  NVIC_InitTypeDef NVIC_InitStructure;
  TIM_ICInitTypeDef  TIM_ICInitStructure;
  /* TIM2 clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

  /* GPIOB clock enable */
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE); //Change here, to GPIOA

  /* TIM2 chennel2 configuration : PA1 */
  GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_0 | GPIO_Pin_1| GPIO_Pin_2 | GPIO_Pin_3  ;  //Change here, to pin 10
  GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP ;
  GPIO_Init(GPIOA, &GPIO_InitStructure);   //Change to GPIOA

  /* Connect TIM pin to AF2 */
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource0, GPIO_AF_TIM2); //And change to pin 1
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource1, GPIO_AF_TIM2);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_TIM2);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_TIM2);
  /* Enable the TIM2 global Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);

   /* ---------------------------------------------------------------------------
    TIM2 configuration: PWM Input mode
     The external signal is connected to TIM2 CH2 pin (PB.03)
     TIM2 CCR2 is used to compute the frequency value
     TIM2 CCR1 is used to compute the duty cycle value

    In this example TIM2 input clock (TIM2CLK) is set to APB1 clock (PCLK1), since
    APB1 prescaler is set to 1.
      TIM2CLK = PCLK1 = HCLK = SystemCoreClock

    External Signal Frequency = SystemCoreClock / TIM2_CCR2 in Hz.
    External Signal DutyCycle = (TIM2_CCR1*100)/(TIM2_CCR2) in %.
  Note:
  SystemCoreClock variable holds HCLK frequency and is defined in system_stm32f0xx.c file.
  Each time the core clock (HCLK) changes, user had to call SystemCoreClockUpdate()
  function to update SystemCoreClock variable value. Otherwise, any configuration
  based on this variable will be incorrect.
  --------------------------------------------------------------------------- */

  TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
  TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
  TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
  TIM_ICInitStructure.TIM_ICFilter = 0x0;

    TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;
    TIM_ICInit(TIM2,&TIM_ICInitStructure);

    TIM_PWMIConfig(TIM2, &TIM_ICInitStructure);

  /* Select the TIM2 Input Trigger: TI2FP2 */
  TIM_SelectInputTrigger(TIM2, TIM_TS_TI2FP2);

  /* Select the slave Mode: Reset Mode */
  TIM_SelectSlaveMode(TIM2, TIM_SlaveMode_Reset);
  TIM_SelectMasterSlaveMode(TIM2,TIM_MasterSlaveMode_Enable);

  /* TIM enable counter */
  TIM_Cmd(TIM2, ENABLE);

  /* Enable the CC2 Interrupt Request */
   TIM_ITConfig(TIM2, TIM_IT_CC2, ENABLE);
}
//And the Interrupt code: //I have changed nothing in it

void TIM2_IRQHandler(void)
{
  /* Clear TIM2 Capture compare interrupt pending bit */
  TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);

  /* Get the Input Capture value */
  IC2Value = TIM_GetCapture2(TIM2);

  if (IC2Value != 0)
  {
    /* Duty cycle computation */
    DutyCycle = (float)(TIM_GetCapture1(TIM2) * 100) / IC2Value;

    /* Frequency computation */
    Frequency = SystemCoreClock / IC2Value;

        miliseconds = DutyCycle*200;
  }
  else
  {
    DutyCycle = 0;
    Frequency = 0;
  }
}

int main()
{

    TIM2_Config();

    while(1){

        TIM2_IRQHandler();

    }
}


texts: Bridge Rectifier Fails When AC Inputs are Shorted

texts:
I am working on a design that involves powering a 3.3V microcontroller off a doorbell transformer but I am running into an issue with the bridge rectifier failing when the AC inputs to the rectifier are shorted.

There are two basic parts of the design. First, a full-wave bridge rectifier is used to convert the 21V AC supply from the doorbell transformer to roughly 26V DC. A switching regulator is used to deliver 3.3V for powering the microcontroller. A smoothing capacitor reduces the ripple created by the bridge rectifier. That part of the circuit is working as expected and the microntroller can be powered from the doorbell transformer.

The second part of the circuit is simple. To allow the doorbell to be used normally while powering the microcontroller, a switch shorts the AC inputs. This closes the circuit and powers the solenoid in the doorbell that sounds the chime. The issue I am running into is the bridge rectifier failing when the switch is pressed.

I would really appriciate any insight into why the bridge rectifier fails and how the circuit might be modified to prevent the failure.

Bridge rectifier datasheet: DF206ST-G


texts: How to determine the maximum voltage and current ratings of a peltier element?

texts:
I recently bought a peltier with no ratings. None at all. On hindsight, it was probably not the smartest thing to do, but is there any way I can determine the maximum voltge and current values at which it can work? I know it works with a 9V battery.

I'm planning on feeding it with a variable power supply and keep on increasing the voltage, but how will I know when to stop? Any way to distinguish maximum point of peltier?


texts:
Suppose we have the following diode (ideal diode) detector:

In a Course notes, they did the following:

  When the diode is on, it conduct current  \$i_{d}\$ which is also equal to \$i_{d}=C\frac{dv_{c}}{dt}\$, and because the current is positive we deduce that: \$\frac{dv_{c}}{dt}\geq0\$ "

My question is: Why did they ignore the current flowing through the resistance in the previous equation?


texts: Is there a way to be able to conclusively detect/find a cellphone signal jammer?

texts:
I hope this is the right place to ask this. I'm going through a dispute with my employer and I'm being threatened with termination (we are both preparing for a legal battle). A day later I get no cellphone reception in my cubicle when I always had decent signal. I'm suspecting that my employer is jamming the signal (which I understand is a federal crime). Is there a way I can find this or conclusively find out that signals are being jammed? i.e. will a phone behave in certain way near a signal jammer? Or will it just act like there is no coverage. Data has always been a bit slow in my office but I've never had issues with talk or text. Right now everything is completely off. I can't even get a text-message on telegram through on the data.

It seems far fetched since it's such a stupid thing to do, given that it's a federal crime. But the timing is just really off. Also, this new blind-spot seems to be centered around my cubicle.


texts: How fast can I pipe data through a TI Delfino in 1.5 KB chunks?

texts:
Say I program a Delfino with this C snippet:
int main () {
    while (true) {
        byte packet[1536];
        readPacketFromUSB(packet);
        writePacketToSerial(packet);
    }
}

How quickly can I run the loop, copying 1536 bytes from USB to serial?
From the TMS320F28377S microcontroller datasheet:

Multichannel Buffered Serial Port (McBSP):
McBSP clock rate, \$CLKG = \frac{CLKSRG}{1+CLKGDV}\$
where CLKSRG source could be LSPCLK, CLKX, or CLKR.

It seems that the fastest available configuration is CLKGDV=1 and LSPCLK=200 MHz.
So \$CLKG = 100 MHz\$ or \$100 Mbps\$ baud rate.
Considering only read/write times, my loop should run at \$\frac{100 Mbps}{2*(1536 bytes)} ≈ 4.1 KHz\$.
Does 4.1 KHz sound right? Is there a substantial source of overhead that I'm missing?


texts: Is it necessary to have insulator sheets between PCBs and antistatic mats?

texts: I am recommended to use some insulator or paper sheets when testing PCBs on antistatic mat connected to ground via antistatic wrist band. Is this correct way. Why is it necessary to have insulator sheets in between?


texts: Stacking batteries to get 200 volts and 21 amperes

texts:
I need to run an old DC motor that needs 200 V DC, 21 A full load; total 4200 W. I want to see if I can run it on V mount lithium batteries made for cameras.

Each battery has:

A capacity of 14.4 V, 12.8 Ah, 185 Wh*
Maximum output voltage 16.8 V DC
Nominal voltage 14.8 V DC
Maximum discharge current 11 A / 120 W (at 104 °F or less)

Battery Protection

Reverse charge
Over charge (reset)
Over discharge (reset)
Over current (reset)
Temperature protection

http://idxtek.com/products/duo-c190

Could I stack these in two parallel banks of 13 (connected in series) to give me a nominal 192.4 V and 22 A....or will they just heat up and cut out? I do not want to use 12 V lead acid car batteries. The batteries listed above will fit my size and weight requirements. Lead acid will not.


texts: Odd level translator output waveform from 3MHz

texts:
I am using SN74LVC1T45 for level translation from 1.8V to 5V. I have designed a custom board for this. The problem I am facing here is that I am getting desired out from 10Hz to 2MHz but from 3MHz the shape of the output waveform is somewhat odd or in irregular shape when compared to an actual square wave.

I am attaching the schematic I have followed and the snapshot of the output waveform at 1MHz and 4MHz. The output waveform gets worse as I increase the frequency.

I am feeding 1.8Vpp from signal generator and measuring output using high impedance probes.

Please help with this.

Thanks In Advance

Schematic:-

1MHz input

1MHz output

4MHz input

4MHz output

Update:

After reading the detailed response from @SamGibson, I made the signal generator output as unipolar and tested the board.

The following are the snapshots of input and output:

1MHz Input signal from Signal Generator

1MHz Output signal

4MHz Input signal from Signal Generator

4MHz Output signal


texts:
I've designed an analogue front end for EMG signals that I want to turn into a PCB. However currently it runs off of two 9V batteries which makes the end product quite large and heavy. I was wondering how I would go about changing my design (or components) to a single battery supply?

Thanks!

Here's a picture of the the design(I apologise about splitting the circuit picture it's too big to display as one!) I use TL072's for op amps and an ina129 for the instrumentation amp:


texts: Problems H-Bridge on PCB taking all the current

texts:
I try to make a system to lift up and down a door for a chicken coop. When I did it on a breadboard, everything was working correctly but now that I use a PCB, when the H-Bridge is connected, the microcontroller doesn't turn on although I did the same routing as the breadboard and the motor turn but slower than it should and after a few seconds the motor speed decrease more and the H-Bridge is burning but if I don't connect the motor to the H-Bidge, it is burning after a few seconds too.
I use a esp32 as microcontroller, a SN754410E for the H-Bridge, the system is powered by four batteries of 1.5 volt each and I use a OKR-T/20-W12-C DC/DC converter to convert the 6 volts from into 3.3 volts for the esp32 and my oled screen. The motor is connected throught the pin head with the name X2. Three push buttons in pulldown are used for the microcontroller and activate the motor in forward or backward. X1 if for a switch to turn on or off the system without touching the batteries.

I tried to change the routing on the PCB and power the H-bridge by the Vin input of the DC/DC converter but it doesn't work and I have still the same problem although on the breadboard, it works without overheating.
Thank you in advance


texts:
I've built up a small PCB with a dsPIC33FJ128GP804 microcontroller and a 7.3728 MHz crystal, among other components.

While testing it last night I had no problems at all getting it working. It fired right up and the PLL locked at 36.864 MHz (x5) and all was good.

This morning though, I powered it up and I found that it would run for a couple of seconds, then lock up. Or the crystal would start oscillating but then the oscillations would collapse after a few tens of milliseconds. Or, it would power up and run, but would occasionally glitch, then keep running (for example, the 20 Hz blinking LED might seem to miss a few flashes.)

Now I've been able to get it working again, and I'm not sure why. I used some upside down compressed air as freeze spray to see if I could get it to do it again, and that seemed to affect it. However, my freeze spray may be conductive and causing problems with the oscillator because of that. It didn't crash right away; it took about 10 seconds before it started skipping a beat here and there, before finally locking up.

When it tries to start oscillating the current consumption goes up from 20mA (mostly power LED) to around 40mA. Because I have a milliammeter (DMM) in series with the circuit, this makes the supply voltage drop by around ~0.1V, so I can visibly see the power LED flickering when this happens. However, it seems to still have problems with no ammeter. The spikes in current seem random, but once every few seconds - slow enough to capture on a 4 Hz digital multimeter.

I have a hunch that it's something to do with my layout. The original design which I have the PCBs for has the ground for one of the load caps in a non-optimal space, due to a design error. (I initially designed the oscillator section to have a local ground, but I moved some traces and the grounds got split, aside from a small join between them.)

However, I have no idea why this would be temperature dependent. I would thought it would be a go/no-go thing.


texts: Why 8051 microcontroller uses four different ports for I/O instead of using address bus and control signals

texts:
8051 has four ports for I/O .Therefore four peripherals can be connected to it at a time .
My question is why doesn't it use the address bus to activate a specific peripheral ...and then use the data bus for input or output ...then we can connect 2^16 different peripherals to our MCU and have any one activated at a single time
Of course we'll have different read and write signals for external memory and peripherals .
This is how it works in 8085 processor.
Using 32 different pins seems like a waste .


texts:
In short, I want to drive some NFETs directly from some of the BBB's GPIO.

3 of the NFETs will pass 1-3 Amps of D-S current and 1 NFET will pass <1 Amp from the D-S.  As you may know the BBB's GPIO's Vin_H/L and Vout_H/L are like 2V/0.8V and 2.85V/0.45V respectively.

In addition, the source/sink currents on the BBB's GPIO's are like 4mA.  At 1st, I was going to directly drive the gates of two different NFETs (AO3422 and IRLR024N) but started looking for more margin in terms of (logic level) Vgs(th) matching but then starting thinking that the gate's Ciss is very important here (the larger the NFET the larger the Ciss) and now I am 2nd guessing if this is the right approach.  Throw in PWMing and possibly operating in the "ohmic" region (of the NFETs) may prove to be non-desirable for several reasons, ie, not fully turning on and creating excessive heat.

I am thinking of just driving these NFETs (BBB==>74ACT245==>NFET) with just a 74ACT245 (buffer) and be done with it for a simple solution and move on.  Will this scheme work?