texts: What are the properties/advantages of concentric winding?

texts:
I have seen several 4 pole induction motors that have coils wound like this:

Both the main winding and the auxiliary winding have 2 pairs of these coils.
This is concentric winding and I've only found some information about this on the internet, but nothing about why is this made and how this works.
I see the current also has an radial orientation (going inwards or outwards) besides the axial orientation (rotating cw or ccw).
Should this cause any difference?
For instance, imagine I take two overlapping coils (like one from main and one from auxiliary) to make the same pole. Then I have two options, like in this figure below:

In option 1 the current has the same radial and axial orientation in both coils, while in option 2 the radial orientation is he opposite.
Should they produce different fields?
And, disregard of being different or not: How should be the field produced by them?
Will it have a single maximum in the middle of the overlap? Or will it split in two maximums?
Cause I have tested some configurations using those to try to make a 2 pole motor (out of a 4 pole motor) and I have the impression that somehow I always have weaker extra poles, because it works, but it's strange.
I may explain it better here if you want, but I tested several possible configurations and even the best one I got to make a 2 pole motor still have the strange behavior of not accelerating to 3600 rpm by itself, even using only the main winding and giving an initial impulse.
It will always accelerate to 400 rpm or so and then keep that speed. And it doesn't stop there by simple lack of torque, if I try to accelerate it further it brakes down to that speed again quite fast.
Only if I give it quite a speed (like 2000 rpm) before energizing it will then accelerate to 3600 rpm and keep at 3600 rpm.
All of that sounds like it's producing a field with more poles than what I was expecting.


texts:
Based on an electronics lecture, we are dealing now with the preamplifier circuit for a detector. The figure is shown below.

Actual I am having the problem to understand the center operational amplifier part. What is a Op-amp with two capacitors? The only related things I can find are the differentiator circuits and integrator circuits, but non of them having two capacitors inside. What is the advantage over that circuit shown here?


texts: Drawn out question in regards to DC power to battery backup

texts:
Story:
I have a lego train that is modded to run off of a 9v train track rail system that was a control function of 0 to 9 volts when fully on. LEGO does not make the motors that can run on these rails ( such as a regular model train does) and thus have made use of a trickle charge system that has a bridge rectifier and uses the circuit that is included in the LEGO LiPo battery pack that controls the charge time,rate,etc...

Here is a picture of what I have going on.

The system consist of ac wall wart that breaks the voltage down to 9 volts thus is controlled by a voltage control (0 to 9 volts) to metal rails. Train engine has motors that will take the 9v dc power which are powered through the trickle charge setup through the LiPo battery.

Question:
How to I come up with a circuit, diode, etc to switch from this 9v dc power to the LiPo battery in a time of power loss?

Is there a better way to do this whole system as a whole, if needed I supply the needed info such as pics, measurements, etc...

Also so sorry that this is a drawn out story/question(s)


texts:
What is the best way to measure a 40 MHz clock signal?
I tried using an oscilloscope with an 8pf passive probe, and the signal was unrecognizable. Would a logic analyzer work better in this case?
Thanks


texts: Why ARM Cortex M0 prints incorrectly Hello World on UART?

texts:
I am new to ARM CORTEX M0. I am trying to use the Tx pin of UART as debug port.

If I use the XDS200 debugger to step through the code, I am able to see the characters and I can see "Hello World" printed neatly on the Tera-Term through COM port.

But if I let the microcontroller run by itself I don't see any output and the probe connected on the Tx pin shows constant high.

I think only after using the debugger and stepping through the code the signals appear but not exactly representing "Hello World". Following is the part of output I logged from Tera-Term and this is repetitive:

/***********************************************************/

    W

    oldo

    W

    oldo

     Hrl

    Well WHWelo

    WHWelo

    WHrld HoHrl WHoell Weold

    olrl WHrllo

    Welllo

    oell  Hrldo

    Welo o

    oelo o

    oelo  Hrl

    Welo

/***********************************************************/

Following is the main() function code.

/***********************************************************/

    void main(void)

    {

       Configure_peripheral(); /*This function call initializes all the required interrupts and global variables etc... */

       char message[] = "Hello World \n";

       char *ptr;

       for(;;)

       {

           ptr = message;

           while(*ptr)

           {

               UART_TX_BUF = (volatile unsigned char)(*ptr);

               ptr++;

           }

       }

    }

/***********************************************************/

Following is the UART Interrupt Service Routine code

/***********************************************************/

    interrupt void uart_isr(void)

    {

       if(UART_INTERRUPT_STATUS & UART_TXCOMPLETE_I)

       {

              /* Clear UART_TXCOMPLETE_I bit */

              UART_INTERRUPT_STATUS |= 0x02;

              /*datasheet : http://www.ti.com/lit/ds/symlink/pga900.pdf*/

              /*As per PGA900 datasheet : TX_COMPLETE is cleared when the UART_TX_BUF is written*/

              /* Read UART_LINE_STATUS for errors */

              UART_Line_Status = UART_LINE_STATUS;

              /* Transmit flag set here */

              UART_Flag_Tx = 1;

       }

     }

Could someone please help me understand what I am missing to get the expected string "Hello World" printed instead of jumbled up text. I am using a USB-Serial transceiver with operating voltage of 0-3.3v. Thanks


texts: I need help in starting this 7segment from 0

texts:
I am making a control system as my project. Here i have used 2 555 timers one in monostable and the other sin astable. The monostable outputs when process one button is pushed and this also triggers the astable 555 timer. The 7 seg attched to the monostable 555 which is the left one shows how many times the process is initiated and the 7seg with astable 555 shows time taken for the process. Now when i start the monostable 555 the astable 555 starts but it counts from 1 not 0. And also i would like to add that when the process 1 button is pressed again the 7 seg attached to the astable 555 resets and starts from 0 again.

Image of circuit before simulation.

Image of circuit after simulation. As can be seen it is starting from 1.


texts:
I'm having trouble understanding outputs of a BFSK modulator.

$$S_1(t) = cos(πt/T)$$
$$S_2(t) = cos(2πt/T)$$

If the input 0 or 1, how can I calculate the output?

Edit:

There is a formula to calculate the output:

$$Zi(t) = ∫ r(t)S_i(t)dt$$

If the input is \$S_2\$ what will be the outputs and decision? I couldn't find any examples for these formula. Any help is greatly appreciated.


texts:
So in my embedded systems class we were working with DACs and we build a resistor ladder. We then sent data to the resistor ladder using timers to generate sine waves at a certain frequency. This produced the sound we wanted to hear.

Since then I've build a 10bit DAC resistor ladder with a sampling rate of 1024Hz. I'm trying to send two notes at once to the DAC. I take the current value from the wave of one note, add it with the value of the wave of the other note, scale it appropriately so it doesn't exceed the max range, and then send this combined number to the DAC.

Unfortunately, this is creating a very gross distortion sound. Buried in the noise I can hear the chord I'm trying to produce, but why is there so much noise in the first place? Shouldn't making a chord be as simple as adding the sine waves together?


texts: how to electrically isolate a PCB from a heat sink

texts:
I have a set of LED driving lights on my motorcycle that must be wired through a ground-leg pulse width modulation dimmer. The problem is the mounting bracket for the lights is grounded, so the lamp shorts to ground through the motorcycle chassis and the PWM dimmer cant dim the lamps. I had solved this issue by isolating the lamps from the motorcycle's chassis at the mounting point, but this has proved unreliable in the rain, and the brackets I had to use weren't up to the task and eventually broke.

I now need to look at internally isolating the lamp housing from the ground leg of the circuit. I had hoped that when I opened up the lamp there would be a separate grounding lead screwed to the light housing that i could simply disconnect, but it appears that the housing is grounded simply by the contact between the PCB and the housing, plus the PCB mounting screws.

My first thought was to just put some small rubber o-rings between the PCB and the housing, and switch from steel to nylon screws for mounting the PCB, but then I remembered that the LEDs need a thermally conductive path to the housing for cooling.

So the question: how to provide a thermally-conductive, electrically-insulated mount for this PCB?

I've seen mention of mica washers, some mention of electrically-insulating heatsink compound, but nothing that seemed authoritative enough to scream "answer."

The PCB is probably 7cm square, and it is surface-mounted to the lamp housing/heat sink by 4 screws, one at each corner. The PCB's entire back appears to be aluminum--actually it looks more like the PCB is aluminum. More likely there is a very thin PCB laminated onto a piece of aluminum stock, pretty cool really, first I've seen like that.


texts: How would you monitor a bank of capacitor to tell if they are fully charged.  I would like to display the precent of they're current charged state using an LED bar graph.


texts: partially periodic function and fourier series representation

texts: I am thinking about this for a while but I could not reach a conclusion. If I have a periodic signal let's say a square wave but it is only non-zero for t<100 and t>-100. the function is periodic in this range and outside of this range it is 0. Now I wonder if I can take fourier series representation of this signal and wonder if this FS representation is equivalent to FT of the signal in time domain within that range. Or should I take FT of the signal instead dealing with FS representation. The problem is FT will be challenging to apply to this signal and FS representation is much more friendly to use. Can you enlighten me pls?


texts: What is a simple yet efficient way of converting 12VAC to 5-12VDC?

texts:
I am trying to create an LED pool light that works off a 12VAC input.  Upon disassembling a similar pool light (Intellibrite), I found that they appear to be using rectifiers and perhaps a few small inductors, as well as many large capacitors.

I am trying to do something similar.

INPUT:

12VAC, up to 20 Amps

OUTPUT:

5-30VDC (voltage doesn't matter as the LED driver I'm using can use any voltage between 3-30VDC)
Capable of supplying at least 60 Watts of power (IV >= 60)

What is the best way of accomplishing this?  My goal here is efficiency as well, as well as a simple BOM (less than maybe 20 components).

I considered using full-wave bridge rectifiers, and simply putting HUGE caps on the output.  However, I am not sure if this is a good solution, considering I need 10Amp output, and the capacitor values might need to be humongous.

Any IC that makes this easier is a bonus.

The LED Driver that I am considering is the LT3496 (same one I see used in the Intellibrite).  Also, if there is a better candidate for an LED driver, feel free to sugggest.

EDITS:

Realized the LED driver can support up to 30VDC input, not up to 12VDC.
Corrected the requirement from 10Amps of current to Wattage requirement.


texts: What will happen if I apply 220 dc voltage to a 220 ac load?

texts:
Let say I have a lamp which is operated on 220 V ac.

Instead of applying 220 AC voltage I apply 220 DC voltage: what will happen? And if I want to convert this 220V dc to 220V ac then what should I do?


texts:
The details of this project are too long, so I am not going to bore you guys with them. What I am trying to do is to get the voltage across the right-hand side of the circuit to reach its highest and then drop abruptly to near zero.
But what's happening is that it reaches its peak and then stays at that level (essentially, a voltage clamp). The Zeners are used to clamp the voltage at that level but I somehow need to drop it abruptly right after it peaks. Any suggestions?


texts: Parameterized Instantiations and Module Instantiations

texts:
Is instantiations used above are very much similar to instantiation used in C++?I am new to verilog, yet in the stage of learning it.Like we used a instance of class in C++ at various places, so is it similar to using parametric and module instantiation?
like

//Module Defination
module and4(a,b,c);
   input[3:0] a,b;
   output[3:0] c;
   assign c=a&b;
   endmodule
//Module Instantiations
wire[3:0]in1,in2;
wire[3:0]o1,o2;
and4(in1,in2,o1);
and4(.c(o2),.a(in1),.b(in2));

so with the first view it is clear that we are using different instance of and4 to make different objects as we do in C++, but i am still doubtful that what i am thinking is wrong or right?


texts: How do I export a single layer as pdf in cadsoft eagle?

texts:
I want to export a single layer e.g. tPlace as a pdf vector graphic. The vector part is optional, is there any ULP that can help me do that?

If I can export it as png or tiff it would also be fine since I can convert them to pdf afterwards.


texts:
I have some problems on understanding how this circuit works. Its aim is that of:

bias correctly the LASER diode at left
send a signal (DATA) to the LASER diode
stabilize the working point of the LASER diode through the feedback system at right

My doubt is about the feedback system at right. I'd say that it will be useful if:

when the light power is too high, the photodetector makes the bias current of the LASER reduce;
when the light power is too low, the photodetector makes the bias current of the LASER increase;

But this schematic confuses me (also because GND and VCC have are taken in a different way). Suppose the light emitted power is too high: the photodetector (a photodiode, I suppose) is flown by a higher current from GND to -5.2V. What does this current cause to the operational amplifier? It is an inverting op amp but I do not know how it works in this case, since I do not know if the current provided by the photodetector goes towards the amplifier output through the feedback, or if it goes towards the resistor where it is written VDC.


texts: Can signal quality be affected by high temp?

texts: I would like to know if UHF signal quality can be affected by hot weather? And which of UHF and VHF is better on that case of weather ?


texts: Is a 1.0 mm thickness for a 4-layer PCB recommended or even common?

texts:
I just learned from the websites of a couple of board manufacturers that they can go as low as 0.8mm on a 4-layer board.

I think going to 1.0 mm (instead of my standard use of 1.6 mm) would be helpful since I am trying to optimize on space. Since there is a high density of traces, it would be desirable to have the convenience of the additional 2 layers during signal routing.

However, due to lack of experience with having 4-layer boards manufactured, I am concerned that issues may come up with a 4-layer board at such low thickness, e.g., problems with blind/buried vias, longterm robustness of the board, problems during pick-and-place assembly, etc.

For my final manufacturing, should I play it safe by sticking with the 1.6 mm thickness?

Or is board-manufacturing sufficiently reliable that I can expect the 1.0 mm 4-layer board to have no issues -- is it common in the industry to go to such low thickness?

UPDATE:

Details of PCB (as requested below):

50 mm X 50 mm
Two Micro-USB connectors present (into which of course USB cables will be inserted/removed)
PCB secured into groove-type slots within plastic enclosure
No long/thin components: Only standard ICs, e.g., QFP-48 microcontroller, voltage regulator, etc.
One "heavy" component: A small OLED display panel is inserted into the 10-pin female headers located on the PCB.


texts: Grounding one port of SPDT analog switch

texts:
We are using a micro-controller to interface RGB matrix (HUB75 connector). Matrix row can be selected using signal pins (A-E). Some RGB matrix suppliers require to use (CLK/DIN/OE) on (A/B/C) pins to serially select/shift row. Pins (D/E) are connected to ground.
When we want to use first type, R1/R2 are soldered down, while R3/R4 are removed.
When we want to use second type, R1/R2 are removed, while R3/R4 are soldered with 0 Ohm.
This require to know in advance which matrix type will be used before releasing PCB (figure 1).
We would like to use analog switches so the matrix type can be selected in the field as in figure 2.
(1) Is it right to use analog switch in order to ground the two pins if connecting second type?
(2) Will the switch resistance (~6 Ohm) have effect since both sides are connected to ground. second type.
(3) Will the switch affect signals at ~20MHz?
Thanks.


texts: Recommended package size and type for a surface mount linear regulator IC that will be hand-soldered?

texts:
I am designing a board that needs a couple linear regulators (5.5v to 3v and 3v to 1.6v) but I am having difficulty selecting a suitable surface mount package type and size that will allow me to hand solder the IC to the PCB without too much difficulty.

I know there is not one correct answer to this but there are so many difference IC package types I don't even know where to start. From doing some searches on digikey it seems that 6mm by 6mm is about the largest you can get for the regulators I am looking at: Linear Regulators

I'm not too experienced in soldering but I do have other people who have more practice that would be able to help. Is 6mm by 6mm large enough for someone with moderate experience and moderate equipment to solder?


texts:
Im working on making a ultrasonic sustain pedal for a keyboard using an Arduino. I've looked up some tutorials on physical home made sustain pedals and it looks like you need to ground all the wires to send the "Sustain" signal. I've stripped some headphone cable to test it out but all 3 of the cables are already touching! Wouldnt that short them? Im assuming something's protecting them from grounding, but how can I ground them myself?

Just to check that the inside cables weren't shielded, I twisted one of the wires and it untwisted into insulator and wire, there was no internal protected wire.

Thanks!


texts: Can a DC power source, such as batteries, cause over-voltage or current spikes

texts:
I'm looking to build a DIY battery power-supply for my Raspberry-Pi3. My electronics engineering skills  are intermediate/novice, and as I had began research on the project, I ran across the following excerpt from a web-article about powering the Raspberry-Pi directly via it's GPIO pins:

  "A more technical (and of course dangerous) way to power the Pi is directly via the GPIO. It should be noted that, unlike the Micro-USB port, there is no regulation or fuse protection on the GPIO to protect from over-voltage or current spikes. If an incorrect voltage is applied, or a current spike occurs on the line you can permanently damage your Raspberry Pi. At best, you’ll “burn out” some or all of the GPIO pins, at worst you can fry your Pi! So be careful."-modmypi.com

Can battery power source cause power-spikes or over-voltage? Should I be considering regulation?


texts: Can I replace capacitor with multiple lower value capacitors in filter?

texts:
Can I replace higher capacitance value MLC capacitor in Sallen-Key topology filter with 2-3 lower value capacitors in parallel (with total capacitance equal to replaced cap)? I tried it in TINA-TI and AC Transfer characteristics are identical. Are there any contraindications to this?

The filter is 0.6..6.4Hz band pass. I started designing it using application report with basic equations, then did a lot of changes to adjust transfer characteristics. Changes include using capacitors with values not available on market.


texts: The contradictions in relation between current and voltage with regards to power and impedence

texts:
What happens in a house if there is a change in voltage due to voltage fluctuations?
assume voltage decreases from its normal value

case 1) V = I*Z

Z does not change unless there is a change in frequency (z=R+jwL)
so  V proportional to I ....

so result is if Voltage decreases current also decreases

case 2) P =  V*I

So if there is a drop in Voltage (v) ,current has to increase to compensate the loss in voltage to deliver the power the load requires

This implies Voltage decreases current increases

Is this not a contradiction? If not how is it resolved??


texts: Do cell phone batteries contain protection circuits?

texts:
I have tens of old cell phone batteries lying around and I want to try to make use of them. I've googled around for the answer, but haven't able to come across anything consistent.

LiPo batteries that you can buy for DIY purposes from places like SparkFun contain a PCB protection circuit attached the cell.

Is something like the circuit on the green PCB included in these types of phone batteries, or is the circuit inside the cellphone?

If so, is the best way to charge these by just using a charge management IC like MCP73831?
If not, how can you make practical use of these cells?
Cellphone batteries also have three or four pins, two obviously for power + and -, the other two for status indication? What exactly are these other two pins for and what is the best way to deal with them for using these batteries in a hobbyist, DIY setting?

EDIT
Additionally, I would just want to use the batteries for low current purposes (few hundred mA at most) and most of them are unused from unused phones.


texts:
How safe is it to use a homemade electromagnet from a microwave transformer such as the one in this link Homemade Electromagnet from Microwave oven transformer
I am helping my 10 year old son with his science experiment but not sure if it's safe.


texts: How to use the power good signal properly?

texts:
I'm powering a circuit from a buck converter. I've seen that many buck/boost converters (for example, TPS62177) have a PG or power good output signal which indicates when the device has managed to regulate its output to the desired voltage.

I am not a power management expert but I'm curious, what could go wrong if I simply disregard the power good output? When do I need to use it and how should I do it properly?

Thanks in advance for your answers!


texts:
I'm extending my question from previously.
How to find SMD resistor and capacitor value and correct size
I'm doing some calculation and find something confusing below is the calculations:
V = 5
R = 1000
I = V/R = 5/1000 = 0.005A
P = IxV = 0.005A x 5V = 0.025W = 1/40W
1/40W is output for me to find the right size of SMD now confusion kicks in when I change the values see below
now let's change this to
V = 5
R = 10000 (10k)
I = V/R = 5/10000 = 0.0005A
P = IxV = 0.0005A x 5V = 0.0025W = 1/400W << that's 400 m'i doing something wrong from the SMD power rating chart i cant any bigger than 1/20 ? how to resolve this?
Now let's come to my real problem see below.
V = 3.3
R = 0.10 ohms
I = V/R = 3.3/0.10 = 33A << ??
P = IxV = 33A x 3.3V = 108.9W = 108 9/10 << ??
See the Circuit and focus on R2 and R3 value. Can someone help to understand me this? or correct me what I'm doing wrong? There is no way its 33 Amps of current for this what will be the correct power rating for this R2 and R3 based on the inputs mentioned on the circuit, V = 3.3 and R2, R3 = 0.10 ohms

if anyone can show me the calculation for the above problems and advise me the correct way of calculation, I have created an excel sheet to make life easy but unable to figure it out whats is wrong when changing the value and if any of you can help me to improve that sheet for the public I'll appreciate
here is the link
https://1drv.ms/x/s!AuEcOHVa1BRjgch-V1bGfitSW3QNbA?e=EJMghY


texts: PSU: Is the DC load current the same measurement as the combined amperage output

texts:
In selecting the right Power supply unit for high performance system, I have learned that besides the watt all the amperage is an important measurement. The following site provided information or advice to look for a combined amperage output while selecting the Power supply unit.

http://www.newegg.com/product/CategoryIntelligenceArticle.aspx?articleId=199

Now, I have been looking for specs for PSU specifications for the PSU in question which is 825W, 80 plus from Dell (see link below)

http://www.itcreations.com/view_product.asp?product_id=37043

In here, the only figure that relates to ampere is the DC load current.

DC Terminal Voltage (V)/ DC Load Current (A)
12V (cumulative of 12V1, 12V2, etc.)
12.1/33.4 (in a typical usage scenario, drawing 457W and providing 416.41W)

So, to my understanding, the combined average amperage would amount to 33.4 in this case.

Is the correct, or do I misunderstand the figures / and if yes, how do I get the real combined amperage output?


texts: Why do application notes/report become obsolete? Am i using a superseded method? Phase locked loops

texts:
Preface
I need to use a phase locked loop to lock onto a signal that can vary from 30Hz to 65 Hz and want to implement it digitally. After some general research I found that Zero crossing phase locked loops were relatively easy to implement in software. So i decided to use this type of PLL.

Question
I was trying to work out how to implement my loop filter and came across these notes on component selection http://www.ti.com/lit/an/snaa015b/snaa015b.pdf. Though these say obsolete at the top, does this mean that the charge pump pll has been superseded by another type of pll?

Me asking you to do my work for me If you know, could you recommend to me what type of PLL i should be using?


texts:
I want to do allocations on a specific DRAM rank. The smallest allocation unit in an OS such as Linux is at the page size granularity, which is typically 4KB. So I need to be able to place at least a complete page in a DRAM rank.
But based on DRAMDig Paper1 and page 20 of Datasheet, volume 1 (M- and H-processor lines) (i.e., my processor chipset family), my Haswell processor uses channel interleaving when DIMMs are placed in slots belonging to different channels (my system has two DIMM, a 4GB and a 8GB). In other words, successive 64-byte (which is, unfortunately, less than 4KB) allocations are mapped to different channels and, consequently, different ranks (e.g., physical address 0 is mapped to rank 0 of DIMM 0 which is located at channel 0, while physical address 64 is mapped to rank 0 of DIMM1 which is located at channel 1), for performance reasons. My questions are:
1) Is it possible to set the channel interleaving bit at a higher order index so as to make 4KB single-rank allocations possible?
2) Otherwise, is it possible to disable channel interleaving purely in software?
3) Otherwise, is placing both DIMMs in the same-channel slots the only remaining approach? This is equivalent to the following statement: channel interleaving does not allow single rank allocations.
Any help, suggestions and guesses are appreciated. I am stuck and the documentations are rather vague.

1 Table 2 on page 5 shows mapping functions (from physical addresses to DRAM components). In all dual-channel configurations, a low-order bit (a bit in the range [6-8]) is used as the channel interleave bit while it should be at least bit 12 to make 4KB single-rank allocations possible.


texts:
I am looking at two kinds of wire wrap wire on Amazon.

The first is the better, more expensive kind. It is silver plated and has Kynar insulation.
http://www.amazon.com/dp/B006C4AGMU/ref=biss_dp_t_asn

The second is a cheaper kind. It is tin plated and has PVC insulation.
http://www.amazon.com/Amico-B-30-1000-Plated-Copper-Wrepping/dp/B008AGUDEY

I am going to use it to connect to LED leads, which are tin plated brass, I believe. So I do not see much advantage in using silver plated wire if the LED leads are not as equally noble. Or am I wrong?

The application temperature should never exceed 150 Fahrenheit (65 Celsius), so is there much advantage to Kynar insulation?

Will it be just as well to buy the cheaper wire for this application?

EDIT: Additional info.
I will be using this hand tool for both stripping and wrapping: Jonard WSU-30M
on page 34 here and how to use here

The LEDs are not specifically made for wire wrapping, but they have fairly stiff tin plated brass leads that have a square profile section, although the edges may not be as sharp as purpose built WW leads.
I did not want to solder to the LEDs at all - using wire wrap only. At least that's the hope.


texts:
I am trying to control my ventilator with a relay. I have found schematics of how to install it. Basically, I would like to immitate a wall switch with a relay to start the ventilator. The board of the ventilator has a weird connector I have never seen before. Does anyone know, what kind of connector is this? I would like to have a "clean" connection with my relay.

Thanks a lot!


texts:
I have a lot of Eneloop batteries and am very happy with them.
However, many of my devices, annoyingly take an odd number of batteries, but the Eneloop charger only charges in pairs.

How bad is it exactly to charge two batteries together that are discharged to different levels?
How bad is it to charge two batteries together that are not even the same age or model?


texts: How to detect a magnetic field from a distance?

texts:
I want to detect a magnetic field, like those of small neodymium magnets, from at least 6 inches away (the further the better, I'd like at least a foot but I won't ask for too much). I'd like to do this on a small board like the Arduino Beetle. And I'd also like to be able to sense polarity. That's it, I just need to be able to detect a small neodymium magnet and possibly it's polarity, nothing more.

I've been reading everything I can on hall sensors but I don't think any of them are capable of detecting a magnet over much of a distance and it seems that the sensor has to be at a certain orientation to the magnet for it to even work. I'm thinking a fluxgate sensor might be what I'm looking for but I'm not sure.

I know it's possible to detect a small magnet from a distance and it's polarity, I just can't find out exactly how.

Could someone point me in the right direction?


texts: How can I build a solar powered car charger?

texts:
I found 12 solar panels, but they are very thin and fragile. They put out approximately .5V under an incandescent bulb. What would be the best way to turn these 12 panels into a 12V car battery charger? I am looking at bumping up the voltage to ~13V, possibly by using a Maxim converter. Has anyone else done this? Thanks!

Kyle

EDIT: Schematics would be very helpful. And tips on how to mount very fragile solar panels.


texts:
I want to make a DMX512 transmitter with a STM32F103 using HAL, CubeMX.

I found some documentation like here about the protocol: Lighting-Control-using-DMX512-protocol-on-STM32.

Sadly it does not show code, however, I have some questions about the protocol itself mainly:

These are excerpts from chapter 2 from the manual:

enter image description here

Questions:

"MARK" time between slots: 0 - <1.00 s ... so if the minimum time is 0, why not leave it out completely?
"MARK" before BREAK (MBB): 0 - <1.00 s ... same here? why bother to 'implement' it?
Also in the diagram START TIME is mentioned, but there are no timing requirements for it... how can I know what is allowed?
In this GitHub file some code (non HAL, but STM32) is shown where there are many remarks about time critical functions, but according to Table 1 there is for most items max. 1 second time, this I would not call time critical. I know HAL/CubeMX tend to have quite a lot of overhead code, so I wonder if this will give problems.

If someone has more information about a DMX512 transmitter, preferably using HAL/CubeMX, I would like to hear about it (couldn't find any example/code).


texts:
I'm a programmer by nature, but I thought I'd try dabbling in programming a micro controller.
I've hooked up my voltage meter, and have figured out how to switch my output ports on/off, and they're currently outputting 3.3V.
What must I do to increase the output of my DigitalIO pins to 12V? I've seen others doing this, but I have no idea what it looks like.
Thanks in advance.

Edit
I'm assuming I need something along these lines, but I'd still need to learn how to actually get the right stepping so that I don't fry anything.


texts: Mechanical 5V Relay with High Voltage Trigger

texts:
I am trying to understand how to make a mechanical relay close with a 5V signal, from an ESP.  Normally I would just try to find a module out there but I am trying to make this relay fit on my PCB.
I found the diagram attached for a relay designed to close on a low voltage signal, but it would be better for my application if the relay was active at high level signal.  Can the circuit below be altered to close the relay at 5V instead of low voltage signal?
http://wiki.sunfounder.cc/index.php?title=2_Channel_5V_Relay_Module#For_raspberry_pi


texts: D flip flop unwanted reset when driven by microcontroller

texts:
I'm trying to implement a digital output that would hold its state while the microcontroller resets. I'm using a 74hc74 and a Particle Electron board. I can latch in the data, but if I reset the board with a high state on the output of the latch, the latch changes state. The low state is persistent during MCU resets. The worst part is that the flip flop changes state while the RESET pin is active, not during reboot.

What could be the cause ? What is the best practice to implement a persistent output while avoiding unwanted state changes ? (both software and hardware aspects) Should I consider some other type of latch instead ?


texts:
I just came across this tube RIAA preamp on which there is a coil on the input capacitor, can someone please explain what's the reason of such thing? The schematic and the actual circuit bellow.

The site with the full circuit and details is: http://www.colvero.com/valvulados/Pre_Amplificador/index.htm it's in portuguese thou.


texts:
I have a small 12v aquarium pump (submersible), and I'd like to hook it up to a small solar panel and put it in an outside pond. This would mean cutting some leads and soldering. Pretty simple job. For inside work, I would usually just put some electrical tape or heatshrink around the joins, but in this case, the joins will be exposed to the weather (but not submersed in water).

What's the best way of waterproofing joins like this? Heatshrink + silicon? Hot glue? Something else? If there are multiple options, what are the pros and cons of each?


texts: Is BBY40 a good substitute for MV209 in this RF receiver?

texts:
VD1, indicated by the red circle in this
is a varactor diode and the suggestion given for the varactor diode in this manual is MV209. It seems to be outdated and so are many other components. How do I find good substitutes? Why is a varactor diode used here instead of a trimmer cap?


texts: How to configure the SPI pins(MOSI,MISO,sclk and SS) for ATMEL ATSAM3X8E?

texts:
I am using ATMEL studio 6 for programming and novice in embedded systems.At present, I have read the theory working of SPI. I understand that I have to set particular bits to one in the control register for defining master or salve mode of operation and clock polarities, phase etc.

Problem:1) How to configure MOSI, clock and select_line as output pin from the master and MISO as the input pin to the master?.

2) Master and slave both are micro controllers,I just need to transfer and receive data to and from slave. So should the master code be dumped in the master mc and slave code should be dumped in slave mc? or both mc's must have the entire code into them?.

3) What are the main factors and key points should consider while SPI programming?.

Any help, suggestion and directions regarding this would be appreciated.Thanks.


texts:
I have the following code:

#include "stm32l1xx.h"
#include "..\Library_SDM.h"
#include "..\Utiles_SDM.h"

int main(void){
unsigned char value = 'A';
Init_SDM();
Init_LCD();
// User button as Digital Input
GPIOA->MODER &= ~(1 << (0*2 +1));
GPIOA->MODER &= ~(1 << (0*2));
// No pull up-pull down (default)
GPIOA->PUPDR &= ~(11 << (0*2));
// Blue LED digital output
GPIOB->MODER |= (0x01 << (2*6+1));
GPIOB->MODER &= ~(0x01 << (2*6));
// Blue LED as USART
GPIOB->AFR[0] &= 0xF0FFFFFF;
GPIOB->AFR[0] |= 0x07000000;
// USART configuration
USART1->CR1 = 0x00000008;  // Oversampling by 16, 8-bit word, Parity control disabled, Transmission enabled
USART1->CR2 = 0x00000000;  // 1 stop bit
USART1->BRR = 0x00000D05;  // BRR= fck/(16*USARTDIV)=(32*10^6)/(9600)=0xD05
USART1->CR1 |= 0x01 << 13; // USART enable
LCD_Texto((unsigned char*)"PRESS");

while(1){
    if ((GPIOA->IDR&0x00000001)!=0) {
        while ((GPIOA->IDR&0x00000001)!=0){
        wait(70000);
    }

     while ((USART1->SR & 0x0080)== 0); // While with no body (to wait
                                        // for the transmission buffer to be ready)
        USART1->DR = value;
        value++;
        }
    } //End of infinite while
}

When you press the button provided in the discovery board, the letter A is shown in the computer terminal (using Tera Term) and if pressed again is shown letter B and so on. The device is programmed using a 9600 bps configuration with a frecuency of 32MHz.

If I change the BRR value to be 8AE instead of D05 the communication will be 14400 bps which is what I want, but the program does not work as expected (the program has to do exactly what it is said above but instead of having a rate of 9600 bps, at 14400 bps ). I don't know why it does not work at 14400 bps since I guess it is just how fast the information travels, or am I getting something wrong?


texts:
Pretty simple question, please point me in the right direction if this has already been asked.

I am designing a board around freescale's IMX23 microprocessor which runs from an external crystal at 24 MHz. I know that I need to keep the crystal close to the proc, but does it matter if the crystal is on the other side of the board (4 layers)? I know that for routing DRAM traces you want to avoid vias like the plague but would I be okay putting the crystal directly underneath the processor? The traces would be extremely short, but the vias would pass through a GND and VDD plane. The alternative is placing the crystal slightly farther from the proc, about 250 mil.

Thanks.


texts:
What is name of the IC manufacturer with this logo?

Probably it is Chinese manufacturer. I wasn't able to find it here or here.

I need to find specification or datasheet of its audio bluetooth reciever circuits 1748NRZ-11F and 17280-11C.

These chips are used in bluetooth car media players like this one.


texts: Why are the considered signal and current input of common base and emitter different although both take \$V_{EB}\$ as input?

texts:
This figure is common-base configuration of pnp (I want to have a pic of npn but can't find one)

The input signal and current are \$V_{EE}+v_{eb}(t)\$ and \$I_E+i_e\$

And this is common emitter configuration of npn

The input signal and current are \$V_{BB}+v_{eb}(t)\$ and \$I_B+i_b\$

Though different notation, \$V_{EE}+v_{eb}(t)\$ = \$V_{BB}+v_{eb}(t)\$

So as the input signal in both configuration are the same, how are the considered currents different. Because the common-base pic is pnp so the direction can look different between 2 picture.

In my textbook, it says in the common base, the small change in input signal (caused by \$v_{eb}(t)\$ lead to big change in \$I_E\$. If that's a case then isn't it is the same in common emitter so why the input current in common emitter is \$I_B\$ but not \$I_E\$ and different input resistance \$r_e\$too


texts: Easiest way for USB-C to USB-A adapter design

texts:
I'm looking through USB 3.1 specs and can't find any answer about one simple question.

I'm designing USB Type C to USB 3.0 Female A adapter, which will require USB 3.0 bandwidth (5Gbps) and standard 3.0 supply (900mA@5V). The idea i can't determine - can it be done without special ICs (like TUSB321 or CCG1/2)?

What i'm thinking for now: it can't be done without something like TUSB321 (which determines necessary current through CC). If i'm wrong - i'll be glad to hear it.


texts: Using Arduino as an I2C PSOC Embedded Bootloader Host (ISP)

texts:
I am working on a project which involves using an Arduino alongside several PSOC-049-42xxx chips.

I want to be able to update the firmware on the PSOCs just by updating the hex file on the Arduino and having it push a new hex file to each PSOC.

I've been reading through this but It hasn't really helped me much. Perhaps someone here could give me some pointers?
http://www.cypress.com/file/137036/download

DropBox Link to arduino project
<< So far I have the API functions provided by Cypress and my understanding is that I need to produce the communication layer functions?

I seem to get a LOT of errors with these API functions however, and I really am not too sure how to port them. Help would be GREATLY appreciated.

As it stands I've got a bootloader project prepared for the PSOC, with I2C enabled and a method for allowing the device to get its own address by reading three bits from external pins. I've got an active I2C bus which I know is working as I've been using it to ping bytes back and forth for other projects. Where I'm stuck is implementing a bootloader host within the Arduino which will parse a hex or cyacd file which is uploaded to the Arduino at programming time, and pass it to each PSOC in turn over I2C.

I'm currently trying to massage these API functions to just stop getting them to throw a tonne of errors before I can even think about how to handle the communications


texts: TTL 7400 NAND gate circuit not functioning

texts:
I recently made a circuit using the ttl 7400 NAND gate IC. The concept is simple. There are two 4 bit inputs going into the 7400 IC. The 7400 IC does a 4 bit NAND operation on these bits, and outputs them. The outputs are used to drive 4 LED's(each LED represents one bit). I made the circuit and it does nothing. The LED's are all off when all input bits are LOW. If I change the input bits nothing happens. Here is a chart to sumarize the behavior of the circuit I built:

As you can see, no matter what the input the outputs is always 0000.

Here is a diagram of the circuit:

Here is the data sheet of the 7400 IC(I'm not sure who manufactured the chip but it says 7400N on it): http://www.ti.com.cn/cn/lit/ds/symlink/sn74ls00.pdf

(The top left diagram on the data sheets first page is the 7400's pinout diagram)


texts: PIC Assembler Bit Wise Operator | Inclusive OR

texts:
I am following a tutorial on programming baseline 12F series PICs in assembler.

I have a question regarding bitwise operators specifically the << left shift operator when combined with the | inclusive OR operator.

For example say I'm using a PIC 12F508 and I want to set the bits to use Timer 0, assign the prescaler to Timer 0, and use a 1:256 prescale in the option register.

I also want the other bits I'm not touching stay set to 1 since the option register by default is 11111111.

Rather than specifying the bits directly such as

movlw    b'11010111'
option

I'd rather address the bits by name as specified in the PIC12F508 include file that way I'm less likely to clear the wrong bit.

Like this:

movlw    1<<NOT_GPWU | 1<<NOT_GPPU | 0<<T0CS | 1<<TOSE | 0<<PSA | b'111'
option

I'd rather not address the individual prescaler set bits by name since I feel it makes it harder to read.

This was introduced in the tutorial and I believe I understand how this works but I just want to verify I understand what's going on.

First off the order of precedence for the bitwise operators are as follows:

~  compliment

left shift  <<

right shift >>

bitwise AND &

bitwise exclusive OR ^

bitwise inclusive OR |

In other words if there are no ( ) parenthesis which changes the order of precedence the operators toward the top of the list will be carried out first.

So since the << left shift it at the top of the list and the inclusive or | is at the bottom. The left shifts are performed first.

For example NOT_GPPU = 1 << 6 since 6 is specified as the bit position in the include file. So 01000000 would be the result.

T0CS = 0 << 5 since 5 is specified as the bit position in the include file. So 00000000 would be the result. This left shift is unnecessary since it does nothing as 0 left shifted 5 times is still 0 but it specifies what the T0CS bit is set to for clarity.

So going down the line from MSB to LSB after the left shifts we have:

GPWU 10000000

GPPU 01000000

T0CS 00000000

TOSE 00010000

PSA>  00000000

--------------111

So now these values or inclusive ORed together by the assembler to get the final value to be moved to the option register.

-------11010111 = Result of inclusive OR

Bitwise Inclusive or truth table:

A   B   Out
1   1   1
0   0   0
1   0   1
0   1   1

So then:

movlw    1<<NOT_GPWU | 1<<NOT_GPPU | 0<<T0CS | 1<<TOSE | 0<<PSA | b'111'
option

Becomes:

movlw    b'11010111'
option

So based on my understanding I don't even have to put the left shifts in the proper bit order correct?

For example:

movlw    0<<T0CS | 1<<NOT_GPPU | 1<<NOT_GPWU | 0<<PSA | 1<<TOSE | b'111'
option

Of course it makes more sense to put them in order but and obviously the last 3 bits are position sensitive because I'm not specifying them by name (PS2, PS1, PS0).

But the same binary output 11010111 should result?

Thanks In Advance.


texts: I was hoping someone here might have an answer for this - is there a version of the 4017 decade counter that is TTL, not CMOS? I'd like to create a project for a bunch of 11 - 12 year olds and I just know they would kill any CMOS chip as soon as they handled it, even with static protection. Any help is much appreciated.


texts: Powering and controlling multiple 12V LED strips with Arduino LilyPad USB

texts:
I'm trying to use an Arduino Lilypad USB to control several separate 12V white LED strips. I am however struggling to work out how to power them.

The LilyPad only operates at 3.3V and I thought a MOSFET would work, but I'm not sure how to do this when I want to control multiple strips. This will all be as part of a costume headdress, so the power supply needs to be quite compact and 'wearable'.

Any assistance would be hugely appreciated.

Thanks,
R

EDIT: to answer the comment on there not being enough info: Yes, I want to turn the strips off in patterns using the LilyPad, so each strip needs to be on a different pin. There will be 4 strips, each of 18 white LEDS. At the moment I have one strip working attached to a 2A MOSFET, 9V battery and the LilyPad. My question is then how I can best connect the other strips and their respective MOSFETs to the LilyPad and the same 9V battery, or is there in fact a better way of doing this.
Regarding size, everything except the strips will need to fit on some kind of fabric pouch on the back of the head.
My plan is just to hack it together and see, but any actual knowledge or advice would be very helpful.

EDIT 2 (current situation): The circuit is working but the lights aren't as bright as they could be. I'm using FQP2N60C MOSFETs, but have no resistors in the circuit. I've also simplified the design, so it just uses LilyPad 2 pins; 3 LED strips are connected in series on one and 4 LED strips are connected in series on the other.  I'm also using one 9V and 2*AA batteries to power the strips.  Any advice on which factor could be making the lights not so bright would be really helpful. Thanks!


texts:
I am trying to establish an UART comunication between PIC32MX110F016 and a RN4020 Bluetooth Module.

I am new on PIC32mx but I think I am doing enough code/configuration for them to comunication but unfortunately they aren't and I really don't know why. I don't know the reason why so I get back to you guys.
This is the code I have made. Does someone has some tip?

#pragma config   FNOSC       = FRCPLL
#pragma config   FPLLIDIV    = DIV_2
#pragma config   FPLLMUL     = MUL_20
#pragma config   FPLLODIV    = DIV_2
#pragma config   FPBDIV      = DIV_1
#pragma config   ICESEL      = ICS_PGx2
#pragma config   WDTPS       = PS16384

#define GetSystemClock()       (40000000ul)
#define GetPeripheralClock()    (GetSystemClock())
#define CORE_TICK_RATE (GetSystemClock() / 2 / 1000)

#define BaudRate   38400

char Message[] = "Hello!";

void __ISR(_UART_1_VECTOR, ipl2)UART1_RX_INT(void){
if(INTGetFlag(INT_SOURCE_UART_RX(
       INTClearFlag(INT_SOURCE_UART_RX(UART1));
}
if(INTGetFlag(INT_SOURCE_UART_TX(UART1))){
 INTClearFlag(INT_SOURCE_UART_TX(UART1));
}
}

void Serial_print(char *buffer)
{
while(*buffer != (char)0)
{
  while(!UARTTransmitterIsReady(UART1));
  UARTSendDataByte(UART1, *buffer++);
}
while(!UARTTransmissionHasCompleted(UART1));
UARTSendDataByte(UART1, '\r');
UARTSendDataByte(UART1, '\n');
}

void uartconfig(void){
PPSUnLock;                        // Allow PIN Mapping
  PPSOutput(1, RPA0, U1TX);     // MAP Tx to RA0 set to digital out
  PPSInput (3, U1RX, RPA2);     // MAP Rx to RA2 set to digital in
PPSLock;                         // Prevent Accidental Mapping

#define UART1TX TRISAbits.TRISA0
#define UART1RX TRISAbits.TRISA2

UART1TX = 0;//output
UART1RX = 1;//input

UARTConfigure(UART1, UART_ENABLE_PINS_TX_RX_ONLY);
UARTSetLineControl(UART1, UART_DATA_SIZE_8_BITS | UART_PARITY_NONE |UART_STOP_BITS_1);
UARTSetDataRate(UART1, GetPeripheralClock(), BaudRate);
UARTEnable(UART1, UART_ENABLE_FLAGS(UART_PERIPHERAL | UART_RX | UART_TX));
UARTSetFifoMode(UART1, UART_INTERRUPT_ON_TX_NOT_FULL | UART_INTERRUPT_ON_RX_NOT_EMPTY);
INTEnable(INT_SOURCE_UART_RX(UART1), INT_ENABLED);
INTSetVectorPriority(INT_VECTOR_UART(UART1), INT_PRIORITY_LEVEL_2);
INTSetVectorSubPriority(INT_VECTOR_UART(UART1), INT_SUB_PRIORITY_LEVEL_0);
}

int32_t main(void) {
__asm__("EI");
SYSTEMConfig(GetSystemClock(), SYS_CFG_WAIT_STATES | SYS_CFG_PCACHE);
INTConfigureSystem(INT_SYSTEM_CONFIG_MULT_VECTOR); //configure multi vector
INTEnableSystemMultiVectoredInt(); //enable interrupts
uartconfig();
WDTCONbits.WDTCLR = 1; // feed the watchdog
WDTCONbits.ON = 1; // enable the watchdog

uartconfig();

Serial_print(Message);
while(1);
}

For better understanding you can take a look at my schematic:


texts: Why is an analog circuit more susceptible to noise than a digital one?

texts: I have read a lot of information on the internet, but did not find a straight easily understandable answer. Could someone just explain it clearly for me, please?


texts:
I was trying to determine what the impact of impedance mismatching would be to an RF output and I came across this.

About half way down the page, the author makes this claim.

  In general, if the VSWR is under 2 the antenna match is considered very good and little would be gained by impedance matching

VSWR (Voltage Standing Wave Ratio)

Using the following expressions

$$ \Gamma =\cfrac{Z_L - Z_0}{Z_L + Z_0} $$
$$ VSWR = \cfrac{1 + | \Gamma| }{1 - |\Gamma|}$$

If my \$Z_L\$ is 50 \$\Omega\$, then in order to get VSWR < 2, my \$Z_0\$ would be either approach 25\$\Omega\$ or approach 100\$\Omega\$.

If the above is true, then why do people go to such lengths get their \$Z_o\$  engineered correctly or is the author incorrect ?


texts: How do I solder headers so that they always stand straight up?

texts: When soldering headers, usually single and double pins, I flip the board over so the pin rests on the surface and then solder them. They never come out straight. It would be great if someone has figured out how to do this correctly?


texts:
What would be the best N turns, when building a simple layer antenna coil to be resonant to 134.2kHz?
Based on this specifications:
1mm insulated copper wire.
4.5cm diameter.
Minimum length (based on 1mm insulated wire with N turns).

Thank you in advance.


texts: Clipping observed across small resistor when attempting to measure op amp output impedance

texts:
While trying to measure the output impedance of a follower circuit involving a 411 op amp, I connected a small resistor (27ohm) to the output (at Vout).

Using an oscilloscope to measure the voltage drop across this resistor, I saw this (blue is the drop across the resistor, yellow is the input at Vin):

Is this a quirk of op amps? Or is the current so large for the small resistor that it's essentially shorting as the voltage increases?


texts: What controls the MAXIMUM allowed frequency of the sound in electronics? The circuit or the speaker component?

texts: I noticed that on some of my devices, I cannot go further than 22.0 kHz, 32.0 kHz, 44.1 kHz, 48.0 kHz and such but what actually causes these limits?


texts: Building an appliance with two plugs to get double the voltage?

texts:
I just had a silly discussion with someone about voltages. In Europe the usual voltage is 220 V while in some other places it's 110 V.

So we were discussing how to use European devices abroad and my friend asked, do you think one could just add another plug to the device to get 220 volts from two 110 volt sockets?

While it seems to be an awesome idea it most likely does not work because otherwise everybody would be doing it.

So we started trying to figure out why it cannot work. While we both have no clue, I suggested that the 110 volts means 110 volts in total for the entire house. I wanted to finish this argument by arguing that if you plug in a toaster that uses 60 of the 110 volts then there is only 50 left.

Except I know this is wrong because no device "uses up" part of the voltage.

So my question is:

  Please could someone explain to me in detail why (if) it is not
  possible to use two plugs to get double the voltage?

Or else, if it is possible, how it works?

Edit

Just in response to some of the answers: We have absolutely no intention whatsoever to actually build anything at all. This is of purely theoretical interest to us and we hope that we learn something about electricity in the process. Thank you for your concern.


texts: How to simulate a n-p-n bjt using Cadence Virtuoso?

texts:
I had been simulating CMOS transistors using Virtuoso, in which I had used ami06n as model and NCSUanalogParts as library. But for a BJT, when i tried simulating through ADE-L using this config, it gave the following error:

Q1: Instance(of type bjt) requires the use of a model.

Need help.

I'd also like to mention that I'm using the spectre tool.


texts: What is the capacitance of this capacitor?

texts:
On the Uni-t UT61E there is a small smd capacitor on the front of the pcb (side with lcd display) labeled C36. What is the capacitance of this component?

I do not have the component itself.


texts: Converting single-phase to three-phase for City & Guilds 2391 practical

texts:
For my City and Guilds 2391 course, I will be testing a three-phase distribution board with a motor and single-phase sub-main.

I am finding it hard to memorize the test procedures. So for me it's about repetition, but naturally I don't have a three-phase supply at home.

I want to buy a Clarke PC 60 three-phase converter (instruction manual).  Now AFAIK for the single-phase sub-main to work, I would require a neutral because single-phase loads aren't balanced or something like that. It's been a while since I studied three-phase theory.

The converter only has a 4 pin TP and earth plug, so no neutral. I just wanted to check with people more knowledgeable, can I just run a neutral separately from the wall socket feeding the converter? I don't see why not, because it's the same supply.

I might even be able to do it internally for a cleaner install, but I have to return the converter afterwards so I can't be taking it apart.


texts:
PIC18f67j11.
For F_OSC which one i have to use: My crystall oscillator frequency or the real frequency oscillator including my PLL modifications?

I'm trying to match the baudRate of the UART and doesn't work. i've tried all  reg configurations and baudRate formulas but none of them seems to work.

I'm using a 20MHz external crystall (connected in OSC1 and OSC2) with maximum PLL (OSCTUNE.TUN = 01111) xtal for a 4800bit/s to measure energy by the MCP35F501 meter CI.

Here is the clock code selection:

`
#define F_OSC                           20000000
#define FOSC_PLL                        20000000 * 4
#define FCY                             F_OSC / 4
`

`// seleciona clock
    OSCCON  = 0xF0;               // INTOSC = 8MHz; SCS = 00: default primary oscillator
    OSCTUNE = 0b01011111;         // PLL = ON; TUN = 011111: Maximum frequency`

And my UART config:

`
void configureUart(unsigned char uart, unsigned long baudRate) {
`

    RCSTA2bits.SPEN = 1;
    RCSTA2bits.CREN   = 1;           // Habilita recepção
    TRISGbits.TRISG1 = 0;
    TRISGbits.TRISG2 = 1;
    TXSTA2bits.BRGH = 0;        //Low Speed Mode (baud = 8bits)
    TXSTA2bits.SYNC = 0;        // 0 = Asynchronous Mode
    TXSTA2bits.TX9 = 0;         //Transmissão feita em 8 bits
    RCSTA2bits.RX9 = 0;         //Recepção feita em 8 bit
    BAUDCON2bits.BRG16 = 1;     //16bit Baud Rate Generator

    TXSTA2bits.TXEN = 1;        // Habilita transmissão
    UART2_RX_INT_EN = 1;        //
    UART2_RX_PRIORITY  = 0;     // Baixa prioridade de interrupção

    baudRate = 1050;//(unsigned long)(FOSC_PLL / (baud_rate * 16)) - 1; TRYING TO MATCH MANUALY TO VALIDATE THE PROTOCOL :#
    // Calcula o novo valor para o registro de configuração do baud-rate
    SPBRGH2 = baudRate >> 8;   // Atualiza BRG da UART1
    SPBRG2 = baudRate;         // ...
}

`


texts:
What's the fastest way to toggle a bit1 in MPASM for the 14-bit enhanced instruction set? (I'm working with a PIC16F1829)

The code has to be standalone - I mean that it can be called on any moment, without knowing the value of the bit on that moment.

Key criteria is speed here: a program with fewer instruction cycles is better. The number of instructions cycles is calculated as the number when the bit is 0 + the number when the bit is 1, divided by 2.

1: with toggle I mean that the code has to be similar to pin=!pin in C


texts: What is the most economical way to drive an array of single coil latching relays?

texts:
Please read the question to the end.  The answer to this question may be non-trivial.

Replacing a number of 2-coil latching relays with single coil latching relays to save space on the board.  The trouble: single coil relays are a lot more trouble to drive with the current reversal requirement.

Currently low-side switches such as darlington arrays or mosfets are doing the work and they cost pennies.  Here are the common solutions I've thought of which do not work in our case:

An array of h-bridges: Too expensive and not enough room on the pbc board.
The method shown in the picture below (from Maxim) for every relay driven by two low-side switches:  The relay coil voltage is close to Vcc (3V) which yeilds low R values and a total current draw above what the PS can provide.

Capacitor Charge and discharge drive: This method requires large capacitors that are physically too large to fit in the enclosure (defeats the purpose of using single coil relays).
An array of analog switches (one per coil as an on/off switch and two to flip Vcc and Gnd and reverse pol): This might work, however analog switches with low on-resistance are expensive compared to low-side mosfet or bjt switches.

What other solutions are recommended in this case?


texts: Connecting a standalone temperature probe to a Raspberry Pi

texts:
I have a standalone temperature probe.
I have also a raspberry pi.

I would like to get the data from the temperature probe to the pi.

I have thought about cutting the probe and using direct but then found a breakout board would be required to amplify the voltage difference.
(seems futile as the standalone works)

Q. How could i integrate the temperature readings from this standalone device to my Raspberry pi?

The standalone probe


texts: Eagle Schematic and Board layout design for simple opamp module questions

texts:
Hopefully I'm not doing anything illegal, I posted a very similar question a few days ago, but this one is different.
Here is what I've been working on the past couple days, trying out different software finally settling on Eagle. Its a simple mic+opamp module that I want to get printed.

Schematic:

Board:

I'm not looking to do SMD, just want to create a board where I can solder on DIP/through-hole components. (I have done copper pour ground on both layers BTW)

So the questions I have are:

1.Should I be using curved traces?
2.Are the green rings the copper rings where I can solder?
3.Is there anything missing from the board layout? (I'm sure there is...)
4.This is where I'm concerned: are the part sizes going to be OK? Are the distances the between the holes for parts standardized or do they differ?
5.Have I chosen the right part for the interface pins? I just want 3 holes that I solder wires to.

Thank you!

EDIT (7/28):

@Steven, I re-did the PCB design on one layer upon your recommendation. It turned out to not be all that hard, and it was good practice. What do you think?
Although I think I did something awkward here: I put two resistors underneath the opamp IC, beause I figured I could use SIP sockets to elevate the IC and fit the resistors under it. Is this OK?


texts: Determining the required threshold for a filter

texts:
Tinkering with a Freetronics microphone board and an Arduino, I found that the microphone board is quite poor at rejecting noise on its power rail.
SPL (sound pressure level) reported widely ranging values in a quiet room, and after initial confusion I sensed a pattern. If I had an oscilloscope this would probably be a very short tale but I don't, so instead I programmed the Arduino to take 300 samples as fast as it could, wrote them to the serial console and copied them to excel, where graphing them produced this:

600 samples just has more of the second wave, regular as clockwork. Indeed, it probably is a clock pulse, coming out of the USB port I use to listen to the Arduino serial comms.
The cure, I think, is a passive low-pass filter. But what frequency? Unfortunately I don't know how long a call takes to analogRead on an Arduino Nano with an Atmel 328P. If anyone happens to know that, I can compute the interval and the frequency for the pulse.
Otherwise, the question is (take your pick)

How to determine this without a scope?
What's a good cheap scope? (what's cheap for a scope?)
Are those cheap Chinese scopes that require a computer worth having?

Another program to count crests (slope change from pos to neg) against the Arduino clock reveals it's a fairly steady 700Hz.

Epilogue
The documentation for the Nano says it will prefer the power supply with the highest voltage so I tried putting 7V into VIN in the hope that the internal linear regulator would clip the ripple. Victory! Better yet a little experimentation reveals that it actually only needs 6V. Ripples start to appear at 5V8. At 5V9 they vanish plus another 0.1V to seal the deal.


texts: I bought some SMD LEDs like the ones in the picture, supplied by a 12 V adapter. I wanted to supply them individually for a project so i cut them and soldered to a 18 ohm resistor. I calculated its value with an online calculator. The power supply had 3 v and the LEDs needed 50 ma and 2.1 v, as the site said because they are yellow. The shop where i bought the resistors only had 0.5 W ones. After i soldered the LEDs i saw that they aren't as bright as they were when plugged at a 12v supply. What is the problem?


texts:
I am trying to build a circuit that disconnects the output for a brief time when power is connected. However I want the circuit to remain connected after power is removed.

I can achieve the first bit with a RC circuit connected to the base of an NPN transistor pulling the gate of a p-channel mosfet to GND. This works well because my input power is a clean vertical uptick. Meaning the voltage is at one instant zero and at the next 5V.

I have tried keeping the circuit connected using two NPN Transistors connected to the gate of the same p-channel mosfet. The two transistors are in the form of a inverter(not gate) signaled by the input power. This works well if the signal quickly goes from 5V to GND. My signal however has a gentle downward slope to zero. I have tried using a voltage divider and a comparitor to speed up the signal but neither has been fast enough.

Is there any way I can briefly disconnect my output when the input goes from LO to HIGH but ignore the change from HIGH to LO? This would leave my circuit connected at all times except for a brief moment when power is connected.

Edit:

Thanks to @EM Fields I was able to figure this out. I slightly edited the circuit Fields provided.

Here is the Spice simulation,

It shows the main input and the main output.


texts: Is 12V in car same as in computer power supply?

texts:
I have bought a car camera with LCD monitor, exactly this one http://www.dx.com/p/5-0-lcd-car-rear-view-stand-security-monitor-camera-w-5-ir-led-kit-480-x-272-pixels-153662

It is powered by 12V.

Can I try it out at home by connecting it to my PC power supply? There is 12V available in the molex connector.

Thanks


texts: Clarifications about up and down converting mixers

texts:
Let's look at this definition of mixers (reference):

A real mixer cannot be driven by arbitrary inputs. Instead one port, the "LO" port, is driven by a Local Oscillator with a fixed amplitude sinusoid.

In a down-converting mixer the other input port is driven by the "RF" signal and the output is at a lower "IF" intermediate frequency
In an up-converting mixer the other input port is driven by the "IF" signal and the output is the "RF" signal

Now let's consider the wikipedia definition of mixer (taken from the italian page):

  In telecommunications, a mixer is a non-linear circuit, that is, a device that accepts two frequency signals at the input and outputs a combination of the two signals at different frequencies. In the most common output applications a signal is produced which can be:
  1) the sum of the frequencies of the input signals (fout = f1 + f2)
  2) the difference between the frequencies of the input signals (fout = f1 - f2)

Now I have some questions:
I) which is the correspondence between up and down converters circuits and circuits which perform sum and difference of frequencies?

I'd say that:

down converting mixer: takes RF as input and gets fIF = fRF - fLO
up converting mixer: takes IF as input and gets fRF = fIF + fLO

II) Exactly what does IF represent? Let's consider for instance a receiver. The signal that arrives at the antenna is the result of an amplitude or frequency modulation through which a signal which contains some informations (for instance an audio signal) is shifted in frequency and carried by a high frequency carrier signal. Then the receiver will have to reconstruct the original information signal. So does IF represent this signal? Or is the down - conversion to IF an intermediate stage?


texts: What is residual distortion in a THD analyzer?

texts:
Im a bit confused about the concept of residual distortion in audio THD analyzers, for example I have a Keithley 2015 analyzer, the data sheet shows that it has a minimum resolution to measure distortion of 0.0001%, but the residual distortion is 0.004%, What exactly is the residual distortion figure?

From what I understand its like the distortion of the instrument itself, so even if the instrument has a minimum resolution of 0.0001% doesnt that mean that the minimum distortion that can be measured is 0.004%? however I tried connecting the output of my SG505 low distortion oscillator to the meter and it reads 0.0008% which is on spec for the oscillator, so what exactly is going on? I've tried looking for this on Google with no luck.


texts: Sallen-Key active bandpass first order filter

texts:
I have an assignment to manually derive transfer function for this active filter. I tried 2 ways. First I did it with kirchoff and substitution, and I get wrong function, and then I tried control systems approach by dividing it into blocks with feedback, but the function takes almost half a page. Is there an easy way to derive it? I found only provided ffunctions for this and that wont do.

Thanks!

Update: I added link here to my calculations. Va, Vb and Vc denote the nodes. I checked twice, could not find mistakes. http://imgur.com/a/xT8Qj


texts: Power Supply 4.2VDC broken. Freedom of choosing new one

texts:
I've got a broken power supply for charging a lithium-ion battery with the following specifications:
INPUT: 220-240VAC~50Hz MAX 11W
OUTPUT: 4.2VDC 1200mA

As I'd like a new power supply and I don't find one on, e.g. amazon, my question is in what way do I have freedom in specifications of a new power supply?

What I found so far are specifications of switching power supplies like this:

INPUT: 100-240 Volt AC, 50/60 Hertz
OUTPUT: 3 / 4,5 / 5 / 6 / 7,5 / 9 / 12 VDC - 600 mA

INPUT: 110V-240V AC
OUTPUT: 3V / 4,5V / 5V / 6V / 7,5V / 9V / 12VDC
600mA at 3V-6V / 450mA at 7,5V / 400mA at 9V / 300mA at 12V

INPUT: 100-240 V AC
OUTPUT: 3-12 V DC (3,0/4,5/5,0/6,0/7,5/9,0/12,0 V) 1000mA

INPUT: 100 ~ 240V 50/60HZ, max. 500mA
OUTPUT: 5V/2,4A; 6V/2A; 7,5V/2A; 9V/2A; 10V/2A; 12V/1,5A; 15V/1,5A

Is one of these four power supplies eligible as a replacement?


texts:
I am trying to calculate the resistance and power Rating for a resistor. I have a 12V 2A power supply and I'm trying to divide it across different motors that are rated for 12V at 0.32A. I understand ohms law so that i need a resistance of 37.5 ohm but I don't understand the power Rating of resistors and what it means. Does the power rating need to be 7W?

Thanks

Harry


texts: I have a boost circuit. When the gate is low a short circuit appears

texts:
simulate this circuit – Schematic created using CircuitLab
I am using a boost circuit as a constant current load, using an IRFZ44 N-channel MOSFET and an IR2104 low side driver taking the signal from Arduino.
When the signal is low (0) a short circuit appears in the source and the power supply shuts off because of the short circuit.
I am using the Arduino as hysteresis control to get constant current at a different voltage.
The program:
void setup() {
  Serial.begin(9600);
  pinMode(2, OUTPUT);
}
void loop() {
  while (true) {
    float avg = 0;

      avg =  (0.0263935810810811 * analogRead(A0) - 13.51351351351351) ;

    if (avg >= 1.27) {
      digitalWrite (2, LOW);
    }
    else if (avg <= 1.25) digitalWrite (2, HIGH);

    Serial.print("Current = ");
    Serial.println(avg, 3);
  }

}


texts: Can someone explain the interrupt procedure of an MCU when performing calculations inside it?

texts:
Suppose I am reading in a value every 100 microseconds using the ADC of a MCU. I have set up the ADC interrupt as well and inside that ADC interrupt I perform some calculations.

So if the ADC is set to read in the next ADC value every 100 microseconds, the only logical thing that I can think of is that within that period it needs to perform the calculations as well, correct ?

What if the calculations take longer to finish ? Can someone explain the theory behind this?


texts:
I have two question for placement of global fiducials on my board:

In the board below you see two fiducials and a component (SMD connector). I would like to place the connector on the very edge of the board but it would interfere with the fiducials. Is it possible to move the fiducials inwards?

According to this document for fiducial deisgn guidelines, the placement shall be "the sum of 7.62mm and the minimum fiducial clearence" away from the board edge. In my case, the fiducial is 1mm in diameter, with a 2.7mm cutout. Does that mean I have to place it 2.7mm/2 + 7.62mm = 8.97mm away from the board edge?? Is that not a little bit too much?


texts:
My friend owns a factory with a very old machine. This component appears to have failed, but he does not know what it is. It is likely that it is a much larger version of a modern component.

Here is some context:

This panel has a few 3-way On-Off-On switches on it, which raise and lower a number of rollers on the machine.


texts: Can a designer get hold of the PCI Express specification without being a member of the PCI SIG group?

texts:
I want to get hold of the PCI Express specification which is available here
. But when I try to download it, it asks me to login as a member - which requires membership at $3000 per year.

Is it possible to get hold of the specification without being a member, or having to pay this very high fee?


texts: What is the dielectric constant of a fly?

texts: Kind of a random question, It has been a topic of debate in my lab. I guess the more specific question is: what materials is a fly's body made out of, and what are their dielectric properties?


texts: I am using the 3 wire PWM fan. By measuring the signal on the 3rd wire (yellow color) on the oscilloscope, the signal is square wave output. Can anyone tell me how this tach signal indicate the speed of the fan?


texts: Can a more powerful charger burn something?

texts:
I am told that I must use 5V, 1A charger to charge power bank. If I will use 5V, 2A charger then will it burn power bank?

Is that possible?

\$I = V / R\$

Charger give constant voltage and current depends on resistance. That is why I think only Voltage is important and charger must be able to give enough current.

But battery bank may have some smart impulse chip like charger have. It may play with its resistance and voltage may jump.

Also I do not understand if I can plug battery bank in PC's USB to charge power bank.


texts: Separate registers for input and output in microcontrollers

texts:
I'm used to using PIC microcontrollers and they have only one register for input and output.

Now I'm studying MSP430 and I see they provide separate registers for input and output.

So, why is it useful to provide separate registers for input and output?

EDIT

I'm reading this book: MSP430 Microcontroller Basics

Normally this book compares MSP430 with PIC16 family. PIC10/12/16 don't have the register LATx. But PIC16 enhanced has.


texts:
Some of you may remember that I posted a question where I requested some feedback on my PCB design. The design was for a Half-Bridge driven by a IR2113 chip. I went ahead and etched the PCB but unfortunately, only the low side MOSFET seems to switch. In my initial calculation, the bootstrap capacitor's value came out to be 1uF or so. Initially, since the circuit didn't work, I decided to change the capacitor to a higher value (100uF).

That didn't cause any change in the circuit. However, if I short out the capacitor the High-Side does turn on. The gate voltage is around 11V. If I don't short out the capacitor, the gate voltage is around 5.5V.

The low side seems to switch just fine. There is a bit more weirdness to the circuit: the SD pin is supposed to low in order to enable the chip - yet, having it high makes no difference to the output. I am still able to switch the Low-Side MOSFET. Furthermore, it seems that somehow the Lin and Hin pins are switched. If I connect the Lin pin to High, it doesn't switch on/off the Low-Side. Infact, if I take the Hin pin and take it High, it causes Lo output to turn on the Low-Side.

The following is my circuit. C2 is 0.1uF and C1 (bootstrap) was 1uF (as per calc.) but I've changed it to a larger value (100uF) incase I was wrong somewhere. For the load, I have a 1K resistor connected. Vcc is 12V.

Previous Schematic: http://i.stack.imgur.com/T3fRn.png

I have updated the schematic. I hope it looks better now. if there if still some confusion, please let me know. I sincerely apologize for wasting the time of folks here. I understand that the schematic was hard to follow. I drew it in haste and I was also not familiar with ERC and DRC checks and I've just started to read up on them.

Getting back on topic: the PCB layout hasn't changed so I'm not sure if if I should just etch another PCB altogether or not. One of my main concerns is that in the datasheet, the source of the upper MOSFET and the drain of the lower MOSFET are not connected. Instead, they are connected to the load. However, in the various schematics I've seen online (case in point), they are connected. Would this make any difference?

Also note that the datasheet has two bypass caps. One is connected between Vcc and Gnd. The other is connected between Vdd and Vss. In my case, the Vdd is tied to Vcc therefore I'm only using one bypass cap.

I again apologize for the poorly drawn schematic that I posted previously.


texts: FPGA - Synchronous inputs with higher frequency than the board clock

texts:
I'm trying to learn Verilog and FPGA and just bought my first FPGA. It's a Lattice iCEstick.

It comes with a 12Mhz clock but I wonder If I can sample synchronous inputs with a clock faster than that. I don't know much about FPGAs but I think that the onboard clock is just a tool you can use but some parts of the design can use another external clock or no clock at all. I'm thinking about counting pixels in a HDMI connection, for example. It might use a higher frequency.

I guess heat and logic gate change and stabilization time might limit the clocks frequencies.

Am I right about these things? How can I know the limits?

Thank you


texts: Transistor Ic vs Vce Curve Trace for one 2N3906 Shows Weird Scope Display Not Sure Why

texts:
I recently built a transistor curve tracer on a breadboard with my Oscilloscope and Arbitrary Waveform Generator. Most BJT Si transistors (NPN and PNP) show typical/normal traces but one device under test - a 2N3906 - produces abnormal trace when collector-emitter voltage (Vce) goes higher than about 6 Volts. My other 2N3906 parts don't show this "abnormal" effect.
Does anyone know what is the cause of this abnormal trace (transistor or test setup for examples)?
I present a few images below showing my test setup, a good trace, and the weird trace.
image 1: LTSpice showing my simple circuit

image 2: breadboard showing the circuit I am using with scope probes and AWG waveform inputs

image 3: AWG setup

image 4: a 2N3906 transistor showing typical results

image 5: the problem result - a 2N3906 under test where Vce seems to break down after 6 volts DC

Link to my report on this subject
http://www.biophysicslab.com/2021/04/27/testing_transistor_hfe


texts:
I would like to look at negative resistance from a practical point of view, not just theory. Would you answer my questions,please?

The op-amp, R1, R2, and R3 behave as a negative resistance: Rn = - 100 ohms.

R4 is in series with the negative resistance.

1- If I constructed this circuit on a breadboard, Will the negative resistor work as a generator and injects current through AA batteries and damage them? Or the current just stops?

2- If the supply was a transformer with bridge rectifier, Would the bridge rectifier prevent the current form interning the supply?

3- If the op-amp IC is supplied with 12 volts or any value that is different from input voltage, Will that affect any parts of the circuit ?

4- If I changed the value of R4 to be 150 ohms, The current will be:

V = I*R

5=I*(150-100)

I = 0.1 A   ,  Is that right ?

Edit

Rn is the equivalent negative resistance, on of its terminals appears at the non inverting input of the op-amp and the other terminal appears at the ground.

What I mean by AA batter or transformer is we remove the 5 volts supply and put an AA battery or a transformer instead.

I think the output terminal is also the non inverting input because the circuit behave just like a resistance.

For more information about negative impedance converter :https://en.wikipedia.org/wiki/Negative_impedance_converter

Thank you,

simulate this circuit – Schematic created using CircuitLab


texts: Calculating battery life of Arduino + XBee Project

texts:
How do I calculate battery life of Arduino and XBee project?
Here's my information:

Battery's voltage: 3.6, capacity: 780 mAH
Current draw of Arduino + XBee when sleeping = 28,5 mA
Current draw of Arduino + XBee when wake up + transmitting data = 66,6 mA
I have sleep cycle 7.5 seconds, so every 7.5 seconds will wake and polling data for 100 milliseconds

How can I predict my battery's life?


texts: How to power a device using a USB port instead of AA batteries?

texts:
I have a device that uses 3 AA batteries and I would like to power it from a USB port instead.
As I understand I will have to use resistors but I have no idea on which ones.
I have found the following calculator: Voltage Divider Calculator
While it does its work, the wiring shown in diagram is quite confusing:

I guess this is some logical schema rather than real wiring schema.
Question:
What resistor values do I need to get ~3.6V from a 5V USB port, and how should I wire them ?
Is there a better way than using resistors to get 3.6V from 5V?


texts:
There are several LED light chain systems on the market, like the Konstsmide 31V system or various traders' "System Decor" or "System 24". All seem rather similar, but there are no technical specs to be found for any of them.
I was wondering about the properties of those systems and was hoping someone here was familiar with them.

None of the systems seems to use a dedicated LED driver, like one would use for RGB strips or similar. How do these systems handle power distribution across strands and power regulation?
In terms of topology, are the individual strands arrangeable both in series, in parallel and mixed, star-like topologies? (I.e. are the LEDs not simply put in series in a segment?)
From an electrical point of view, can the individual strands be shortened?


texts: Simple oscillator design not working when implemented

texts:
I thought this would be a quick build, but maybe there is something wrong with the design. Even though no waveform occurs, the MOSFET gets very hot.

f = 1/(2π√[C(L1+L2)])

An n-channel 2N7000 MOSFET was chosen with the Hartly configuration to make a 160 kHz oscillator with an output power greater than 16 dBm (or 0.0398 W).

The tank circuit has L1 = L2 = 50 nH and C = 10uF.

Find choke:

\$A_V = g_mR_D\$

\$A_V = (2\sqrt{K_nI_d})(L_D2\pi*f)\$

\$10 = (2\sqrt{4*0.002})(56*10^{-6}2\pi*160000)\$

\$L_D = 56uH = L_3\$

Find Cc:

\$160k = 1/(2\pi*L_{3}C_{c})\$

\$C_{c} = 18uF\$

Find R1:

\$Let: V_{GS} = 2\$

\$10=RI_D + V_{GS}\$

R = 4kΩ

Should I redesign something? Should I add a buffer stage of some sort?

Should I just start the implementation from scratch again? Should I give up on trying to use a FET for this application? Why?

I also swapped it out the Hartley tank with Colpitts, but the signal rapidly attenuated within seconds. If I said that correctly:

I also looked at the others, but they all use BJTs. I really wanted to use a MOSFET to be unique.

This one isn't really about my situation: AC analysis of a oscillator
My choke is bigger, but their's is for higher frequency: Colpitts not oscillating as expected


texts: 8:1 Multiplexer With 5 Parameters of F(A,B,C,D,E) = ABCD +B'CDE+BC'D'

texts:
I am trying to create a multiplexer 8:1 with 5 parameters of the function $$F(A,B,C,D,E) = ABCD +B'CDE+BC'D'$$
what I did its to right it as minterms so what I get is:
$$ F = ABCDE + ABCDE' + AB'CDE + A'B'CDE + ABC'D'E' + A'BC'D'E \rightarrow m(31,30,23,7,24,9)$$
now what I need to do? I need some advice how to continue.
Thanks!


texts: I am looking to design an amplifier for the phono output on my turntable. The output is presented as two RCA jacks on the back of the unit. Is it safe to assume that the ground of both the left and right signal are the same, or should they each be treated as separate differential signals (with the positive signal being the center of the jack and the negative being the casing)?


texts: Is it possible to program the Teensy3.0/3.1/3.2 in C?

texts:
I need to program my Teensy3.2 (hasn't arrived yet) in C. Looking at the Teensy pinouts page, the last board for which pinouts for C language are given is the Teensy++ 2.0. Is it still possible to program the Teensy3.2 in C? If so, what are it's pins called in C?

Thanks!

evamvid


texts: Does this special case of Rayleigh's monotonicity principle hold true for the norms of complex impedances?

texts:
Take a dipole made up of a set of nodes (i.e. resistors) \$R_1,R_2\ldots,R_n\$ that are connected by vertices (i.e. wires) in any given way. Rayleigh's monotonicity law states that the effective resistance of the dipole, \$R_\mathrm{eq}\$, is an increasing function of each of its variables \$R_1,...,R_n\$; that is to say that increasing any \$R_i\$ will amount to an increase in the effective resistance \$R_\mathrm{eq}\$.

A consequence of this principle is that adding an extra vertex (i.e. a length of wire) within the dipole will always reduce the effective resistance. Indeed, we may consider that the absence of a length of wire is equivalent to the presence of a resistor with infinite resistance. So adding a vertex is equivalent to reducing its resistance from \$\infty \ \Omega\$ to \$0 \ \Omega\$. Hence we may apply Rayleigh's monotonicity principle.

I was wondering if this can be generalised to the norms of complex impedances. That is to say, does adding a vertex within the dipole always reduce the norm of the impedance of the dipole?


texts: I am routing a PCB that uses a USB connection. The differential pair traces are 10 mil distant from each other, and they are about 1mm different in length. Is it going to be a problem? What is the recommended maximum difference in length and the minimum distance between them?


texts:
The output stage of my circuit is a 2nd order inverting low pass filter.  The input should be negative (DC), thus yielding a positive output (DC).  It is possible that the input could be positive, but I don't want a negative output, so I grounded the negative pin of the op amp in the filter.  It's not rail to rail but I should never be close the the bottom rail anyway.

My only real question was, am I supposed to still put bypass caps on the negative supply pin, which is grounded? That seems odd, because it would just be a cap from ground to ground, and seems useless, but I could be wrong.

Here's a picture showing part of my schematic:

The bypass caps network is not shown, but present, with 4.7uF and .1uF caps to ground.


texts: Why is there no Phase Shift in CC and CB Configuration

texts:
I am curious why in common base and common collector configurations there is no phase shift between output and input (at low frequencies, where stray capacitance doesn't "kick in" yet)?

I get it why there is a phase shift in common emitter configuration. If the signal at the base (input) is increased, then the collector current through collector resistor R also increases, which makes a larger voltage drop across it. According to formula \$V_{CE} = V_{CC} - Ic*Rc\$ it can be easily seen that \$V_{CE}\$ decreases as \$V_{RC}\$ increases - therefore 180° phase shift.

In case of common base, as the signal at the emitter (input) increases, \$Vc\$ also increases as \$Vc = V_{CE} + V_{RE}\$. \$V_{CE}\$ increases as input signal is increased. But shouldn't it decrease just like it does in CE configuration? Why does collector current increase with increase of emitter current anyway?

CB configuration is more logical to me (regarding phase shift), since output is taken from emitter, which just follows the base (input).

I am not certain if I understand phase shift of any of above configurations at all. Sources always say that there is or there isn't any phase shift in certain configuration, but they never say why is it the way is it - the explanation behind that fact. And that is what I would like to know.


texts: Need help identifying this chip on a old board

texts: Hi Can any body assist in identifying this chip (I think its Ram) probably an easy


texts: Single phase heater loads on 3 phase supply

texts: I have two single phase heaters (same rating) that I have to connect to a 3 phase supply. Say for example the rating on the heater is 1000W, 208V. And the supply is 208V,3phase,60Hz. I connect heater-1 across L1 & L2 and heater-2 across L2 & L3. For calculating the current on L2, do I just double the current drawn by a single heater or do I have to account for some 'open delta' current cancellation?


texts: LTspice stacks data points on the same vector when I do linear parameter sweep

texts:
I am trying to export the voltage of a transformer for different mutual coupling values. However, when I do a linear increase of mutual coupling it seems that LTspice will stack the parameters in one vector. Thus, I don't know what voltage corresponds to mutual coupling.

On top of that, LTspice does not simulate with a fixed number of data points so I just can't break the vector to equally smaller vectors.

Selecting the "list" as the nature of sweep will show me the data points corresponding to the mutual coupling. BUT list works only for 3 different parameters which is not helpful to interpret my results. Is there any way to increase the number of parameters for a list sweep?

Let me know your suggestions or alternative to tackle this problem.


texts: Which equation can be used to calculate the time taken to charge the capacitor at the given amount of current and voltage at a constant capacitance?


texts: Replacing push button by transistor in 555 circuit

texts:
TL;DR: I need to replace the button S1 by a circuit/component that could close the circuit which the button is closing by applying a 5V signal (with 0.5s duration) in the new circuit/component.

Well, I started designing some circuits without microcontrollers, so I could study and learn the functionalities of some components. In this circuit I tried to implement a toggle effect in the 555 OUT pin, I mean: when I press the button the OUT goes high, when I press it again it goes low and so on.

The circuit works with the physical button, but I need to toggle the 555 OUT with a 5 volt signal with duration of 0.5s.

I tried to figure out a solution but it's terribly expensive and complex in my opnion. So, what's the best circuit/component could I use to replace this weird solution?

Original circuit:

My solution:

Any help would be appreciated!

Cheers.


texts: Transferring from Serial to RF communication

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I am running an application that takes information and sends it over the serial port, with some processing etc done on my proprietary board (using an ATMEL simple Micro-controller). I am testing to check on how much stress I am putting on the micro-controller to verify what I will use later on with my application depending on the stress levels I see.

Now serial is one thing, but I would like to communicate wirelessly to transfer my information (can be from a few kb to a couple mb of information). Should I see any major differences in the stress on the processor if I'm communicating through serial as opposed to RF?

I have never really done anything with RF before (I'm a student), so I'd like to have some sort of idea on the different amounts of stress on this could induce compared to serial comm before I actually buy some more parts.

Thanks!


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I am trying to understand:

1) how the following circuit works and more specifically how it turns on.

2) How to to modify it to get a hold on/hold off behavior instead of push on/hold off to prevent accidental turn on.

It is a circuit found and partially documented here.
I have tested it in the auto off position and it works as expected.

I do understand how the circuit switches off but not how it initially turns on. How is the P-MOSFET gate pulled low when the button is pushed?

EDIT: I have designed a circuit on faltstad here for simulation. I tried Mohamad's idea but it didnt work. So the question remains: how to have a hold-on behavior, without loosing the auto-off (circuit initially off when powering it)?


texts: Can you explain this basic circuit to me? Why is the transistor switch off?

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I am pretty new to the world of electronics so apologize yet again for a very basic question.
I am trying to understand the functioning of a transistor, but my confusion may underpin some more fundamental confusion about voltage. I think understanding this circuit will help me grok the fundamentals.

When the button is closed like in picture, the light is off. I actually built it and verified that when it's closed, the voltage between base and emitter is actually zero, and the voltage across the 1k resistor is around 0.8V. I also found that when increasing this resistance to around 5k or more, the transistor is on whether the button is pressed or not.
I do not understand why is the voltage 0 at the base and why it's always on when the bottom resistor increases. The explanation in the text doesn't make sense. Could anyone help me understanding this?
Thanks


texts: Taming "spiky" AC voltage source, need to reduce the max amplitude

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Input

I've been tasked to find a way to convert the output of a peculiar AC permanent magnet generator, so that it powers a lower voltage device. The output of the generator looks like this (at the most problematic speed setting):

(I have misplaced the scope snapshot, but this is very much like it as I've recreated it from my notes).

Notice the problematic spike. Its amplitude is almost 100V. The RMS voltage is only about 35Vrms. Frequency is ~200 Hz. The generator may also turn slower, the lowest speed gives you around 12Vrms, 75 Hz. Load doesn't have much effect on the waveform, we tried with a 10 ohm load on the 12Vrms case and the waveform didn't change appreciably.

Output

The target device has a diode bridge and a DC-DC converter inside, and consumes ~5W. Unfortunately, it was originally designed to handle up to 35V DC and features 60V absolute max limit. It will be fine to run on any voltage (AC or DC) at 5V or more, as long as the absolute max is not exceeded (the abs. max rating cannot be improved easily).

Some ideas

I've been thinking about ways to do this conversion and they are all clumsy, or so it seems:

Use a 2:1 transformer (bulky)
Use a big passive filter (bulky, not cheap)
Rectify, then make a crude high-voltage LDO (would need serious heatsinking)
Rectify, then use a pass transistor and pinch it off when the input voltage exceeds e.g. 50V (I think the inductance of the generator will kick the pass element very hard, to kilovolts)
Same as 4, but instead of blocking, short the overvoltage to ground, with a thyristor (might work, but again will probably require heatsinking).
Rectify, then DC-DC (seems like an overkill).

Ideally I'd want to make an adapter board, to be produced in modest volumes, with a BOM cost of a few dollars, say $5 max.

Which option should I go for, and am I missing some other approach?

EDIT:

I finally was able to actually physically see the generator in question and measure some things:

Coil inductance is 1.5-2.0 mH
Coil resistance is pretty low, less than 1 ohm
The output of the generator actually looks very different when loaded, the slow ramp parts are close to zero and only the spikes are present. I suspect the guys that previously tested it didn't connect the load properly.
I wasn't able to test it shorted, but I'm inclined to think it will tolerate a short circuit.


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I've been trying to find the name, part number, manufacturer and some vendor for this hook socket. I'm not even 100% sure that is what it is called.

Do you have any information about it? Anything would be welcome.


texts: Flyback transformer temperature rise - reasonable value

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I had build an flyback converter based on UC3845 and some high voltage mosfet - it works fine, however I've got one problem with it. (but i'm not sure if that actually is a problem)
The core for the transformer I used is taken out from laptop power adapter (19V @ 3,5A). From what I reserached - this is RM10 core:

I'm getting 24V @ 2,5A from it, the transistor and secondary diode heats up, but has resonable temperature on the heatsink (40degC), However the transformer is getting quite hot (65-70degC) after some time.
This is the primary current of the transformer - it shows no saturation.

Is it normal for this size of core to get to those temperatures at those powers? If not - What is causing the excessive heating?
EDIT:
Here is the schematic:

And there is the secondary waveform at rated power (24V @ 2,5A):


texts: Function Generator Voltage and Current handling

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I am using this Function Generator

My circuit :

FG input : 5V peak to peak. 1kHz. 1ms time period. 90% duty.

I want to understand the below questions :

Is it safe to do this connection?
I have read that we need to take care whether the input BNC channel output of the FG should be capable of handling the voltage and current? Which is the voltage it must handle and what is the sink current?
How to check in the datasheet of the FG regarding this?

Actually, the FG output BNC channels only produce output voltage right? How to check how much of input voltage that they can handle when they are impressed on those channels?


texts: what is frequency divider and how does it work with d type flip flop circuit?

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I am trying to learn about these things but I have very hard time to understand frequency divider and the leading edge and trailing edge of voltage.

Please, help is needed if someone explain it in easy way. Or could someone route me to any good resource of learning these things.

Currently I am reading the book named "CODE the hidden language of computer hardware and software" but I am stuck at chapter number 14.


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I want to build a device which should act as a USB keyboard. I've found a
SAM3-H256 board to be fairly easily available in my country. I want the device to be:

fully USB-powered (no additional power sources),
fully USB-programmable (from PC; no JTAG or other external debuggers), using free tools (e.g. GCC),
not to have to attach any additional elements (apart from a few on/off keys to be used to trigger sending keycodes to PC), especially not to need anything additional to make it to work over USB.

I'm a newbie in electronics, and therefore I'd like to ask what would be the most serious problems I should expect to face with this board and requirements as described? Or shouldn't I expect it to work in such a configuration at all?