texts:
I am doing a DIY PDU project for my college using an Arudino and I have 8 16Amp relays that are controlled via the board. I want to make some sort of surge protector for it as well.

Basically I want to know what fuses must I use for the mains input and what Varistors should be used. There will be one 220V input plug and that will feed 8 220V 16 Amp plugs on the outputs controlled by relays.


texts:
I have a atmega32u4 with 8Mhz and try to generate a clock signal with 1,2 or 4 MHz using timer 4 and output it on PD6 (!OC4D)

For timer 1 and on PB5 (OC1A) I used CTC mode:

TCNT1=0;

// Toggle OC1A on Compare Match
TCCR1A = 0x00;
bitSet(TCCR1A, COM1A0);

// Clear Timer on Compare Match
TCCR1B = 0x00;
bitSet(TCCR1B, WGM12);

//8Mhz
// Set frequency (0 = 4Mhz, 1 = 2MHz, 3 = 1MHz)
OCR1A = <value>;

// No prescaling
bitSet(TCCR1B, CS10);

but timer4 does not have this CTC für OC4D (or have I got that wrong from datasheet?)

Is there another way to create that output?


texts: What are possible alternatives for a depletion PMOS

texts:
I need a fast reacting way of discharging a capacitor and I figure a simple depletion PMOS is what I need. The time at which the gate has to have a voltage to keep the depletion PMOS closed is not important. It's taken cared of by the rest of the circuit.

Problem is, as all you know, depletion PMOS are not being manufactured (not economical enough??). So what are similarly behaving devices, preferably having the same footprint.


texts: MATLAB model of an op-amp's Open Loop Gain

texts:
I'm using MATLAB to analyze an amplifier in a transimpedance circuit, and I'm a little lost in implementing the op amp's open-loop gain function with the following formula:

$$A(s) = A_{OL} \cdot \frac{\omega_0}{s+\omega_0}$$
$$A_{OL} = \text{DC Open Loop Gain, a Constant}$$
$$\omega_0 = \text{Corner Frequency, -3dB from }A_{OL} $$

Using parameters from the OPA656 by TI as a model, I've used the Gain Bandwidth Product (GBW) and the DC Gain to find the corner frequency.

$$GBW = 230 \text{ MHz and }A_{OL} = 65 \text{ dB}$$
$$\omega_0 = \frac{GBW}{10^{\frac{A_{OL}-3}{20}}}$$

What I'm confused about is how the given -3 dB bandwidth and the unity-gain bandwidth factor into the equation. Using the equations, I found that the corner frequency is at 182.695 kHz, and that appears to match up with the values shown in Figure 14 of the datasheet. The datasheet gives a value of 500 MHz for both of them, but the figure in the datasheet seems to extend beyond past that. How can I incorporate the given -3 dB bandwidth and the unity-gain frequency into my equation, or is it not necessary for the model shown here?


texts: Is there an IC with a large number of digitally controllable switches? And if so, how could I control it?

texts:
Okay so I'm looking for an IC or anything that contains a large number of controllable switches.

Say for instance, 100 switches.  Each switch must have an independent input and output.  I don't want to select from them, so I don't need a mux/demux.  I essentially want all 100 of them to be individually controllable, which I suppose would require 100 bits of control, so if an IC did exist it would have to be at least 300+ pins

Is there any way to do this? I'm doubtful that there's an IC that can do this, but maybe there's a solution I haven't heard of.

Any help is appreciated. Thanks.

EDIT with crosspoint

So I realize I could connect different points to every other point with a crosspoint switch that had 2x as many pins as connection points, sort of like this.

But this results in a lot of wasted switches.  Out of the 16 switches in this 4x4 crosspoint, only 6 are needed, so 10 are wasted.

Optimally, I should only need 6, like so:

Also, I think it's possible to connect by using a cross point that has the same amount of total IO as connection points I need, like this:

But to connect any point back to the same side, I would have to use up one of the points on the other side. Like {A-C-B}


texts: How to properly define BGA footprint in Eagle?

texts:
This question is somewhat relevant to this one. However I am sure it well deserves to be separate.

I created a custom device/symbol/footprint for an ARM MCU. However I am doubtful whether I created a footprint correctly. The MCU documentation defines dimensions as below:

When I was defining pads I used SMD pad with 100% roundness and 0.5x0.5mm size. Which resulted in below output (layers visible are top, tStop and tCream). Which looks like it won't be possible to send even a single trace between the balls (due to tStop size):

Now, my understand is that traditionally there is enough space left between balls for at least a single copper trace, which does not look like it is happening from above picture.

My question: Did I read/understand package dimensions from the documentation correctly? Did I define the pad size correctly? Or it should be smaller? In other words, what is the proper way to define footprint of the BGA device using Eagle?

UPDATE: Found this document which obviously applies mostly to TI chips, but there is a section of "Standard BGA", which I think should be very useful. It shows different sizes (including ball landing size etc).


texts:
I've been quantifying the peak to peak level of noise on a 24V Zener diode.  The noise distribution is log normal, consistent with the literature regarding avalanche effect. The apparatus is:-

simulate this circuit – Schematic created using CircuitLab

I've asked previously regarding this, as How to measure the amplitude of noise and What is the noise level as read on my oscilloscope and not had satisfactory answers that matched my experiences.  Traditionally noise is measured in V/√Hz.  I suggest that this was the only means as people only had analogue oscilloscopes with smooth continuous traces.  They kinda stuck their thumb on the bit of the screen where the trace topped out, and looked at the 'scope settings.  This became the norm.

We now use digital scopes.  This has changed everything.  For noise measurement on a DSO, there is no concept of noise /bandwidth, and no concept of bandwidth actually.  The peak to peak level of noise only depends on the total number of samples taken.  These samples can be taken at 1 sample /s or 1Gsample /s and this makes no difference to the peak to peak reading (and thus the rms value).  This is entirely consistent with statistics based on discrete sampling.

This is what I get.  The mean Vpp and standard deviation do not change if you vary the oscilloscope bandwidth by applying the 20MHz limiter.  The op amp is rated to 3MHz so this is fixed at all times.  The only thing that affects these readings is the total number of samples taken.  With a mean of 2.30V and a standard deviation of 162mV, I can calculate any peak or rms value within a certain confidence level.

The crux is this:  Noise is a normalish statistical distribution.  A distribution is entirely defined by shape, size and position.  So we have log normal, μ = 2.30V and σ = 162mV.  I cannot for the life of me see how that correlates to an x V/√Hz value, especially since the Hz bit refers to the measuring instrument, and not the source.  Surely the source makes noise irrespective of the measuring apparatus?  Or is it a case of "Does a falling tree make a sound..?"

Given that very most new oscilloscopes are digital with discrete sampling, should we now drop V/√Hz in favour of a statistical approach to noise measurement?


texts: Can Bluetooth beacon be detected while it's in motion?

texts:
I'm curious to know if smartphones can actually detect Bluetooth beacon which is in motion, say while driving. Can car A detects the beacon in car B if they pass each other?

If yes, what is the speed limit and maximum distance?


texts: Ammeter scale, not sure what my amp reading is

texts:
I have a basic multi-meter that I am using to measure amp on a load.

I am trying to figure out how much amps my small entertainment system draws. (LCD TV, PC, speakers.) I want to build a small DC inverter system to feed this entertainment system.

My main power is 220V

My ammeter's lowest scale is 200, the highest is 1000. It only has these two settings. The sale is not marked as amps or milli-amps. I am assuming it's amps due to the missing mA notation.

When clamping around the lead that feeds the whole setup (multi plug), I am getting a reading of 00.3 to 00.4 on the screen (scale, 200).

The system if idling and not really doing anything accept being powered on. Tv screen is on, pc is on, and speakers are on.

I am using this meter. DT266 Multi Meter

My meter, however, just displays "A" (with an Aternating current symbol), and not "ACA".

I would normally assume that this is 0.4 amps . However, that seems low.

Alternatively, I tested this same meter and using the same scale (200) on my car battery charger charging a battery, and there it reads 02.5 . The max amps of the battery charger as written on the label, is 6 amps. So hence 02.5 is then 2.5 amps and not 25 amps.

Which brings me back to my initial question.

Is 0.4 amps a "normal" load for the entertainment system as specified?

Using an online calculator, that converts to about 88 watts.


texts:
I have two 10mm white LEDs
 FW current is 20mA, FW supply is 3.5V typical or 4.0V Max.

I am wanting to connect them to one 9V battery I have a 100-ohm resistor at 1/4 watt 5% tolerance.

Is this a safe set up or do i need to change anything?
The 9V gets a little warm at the moment.


texts: What to do with wire shielding before attaching the plug?

texts:
As far as I understand, the wire shielding is for noise control.

Question

I cut a USB wire in half and am going to apply a 2 pin JST connector to the power & ground. Do I cut the wire shield back out of the way or should it connect in with the ground?

Bonus Question

I recently saw a 5 wire cable with 6 pins at the end so I assume the last wire is the shielding. Is this a common approach? The device was a Microsoft Kinect 360 (v1)


texts: What is this symbol that looks like a parallelogram?

texts:
it says "180ohm at 100MHz" next to it. So I'm guessing that it's a non-air-core inductor. It seems to fit this: What is this symbol on the schematic? - except that the symbol is slightly different than what's in that answer. Wanted to confirm.

this is part of Atmel at91sam3d (ARM SoC) schematic.


texts: Interpreting Data Sheets ("Typical Applications")

texts:
I've recently been researching various transceivers, but I run into trouble as soon as I get to the "typical applications" section of the data sheet.

With the Si4464 for instance, the example application provided does not specify recommended capacitor/inductor values.  The circuit diagram (page 16) is provided below:

There are not footnotes provided for the figure.  The figure is only referenced once in the entire document (page 15):

  Figure 2 demonstrates an application for +20 dBm using an external T/R-switch.

My intuition tells me that the capacitor/inductor values are not specified because I am expected to know how to choose them myself.  If that is the case, what principles should I use to determine the values?  If not, am I missing some crucial information hidden in the data sheet?


texts: RF via impedance calculation with NFP removal

texts:
I'm trying to match the impedance of a RF via from bottom layer to top layer in a 6-layer PCB design. GNSS signal. Unused pad (NFP) removal activated.
The selected via size is 0.9mm pad and 0.5mm drill. No antipad defined so applying copper-to-drill default clearance (0.2mm) at inner ref planes. This results in a 0.9mm ref plane opening.
I'm using Saturn PCB tool and I wonder what data should I fill to get the correct calculation. Internal pad diameter is supposed to be the same as drill diameter? Any help/suggestion will be appreciated.


texts: Interfacing an automotive pressure sensor to microcontroller circuit

texts:
This is a follow up to Measuring water pressure in a tank. I've decided to try and go a different direction so I'm asking a new question.

I have an application in which I need to electronically measure the pressure inside of a pool filter. Because the sensor will be subjected to chlorinated water I can't use a simple pressure sensor such as the MPX5700 from Freescale.

I've got a cheap 150 PSI Pressure Transducer from Ebay with the following technical details:

  Input: 0-150 psi.
  Output: 0.5V – 4.5V linear voltage output. 0 psi outputs 0.5V, 75 psi
  outputs 2.5V, 150 psi outputs 4.5V.

  Works for oil, fuel, water or air pressure. Can be used in oil tank,
  gas tank, etc.

  Accuracy: within 2% of reading (full scale).

  Thread: 1/8”-27 NPT.

  Wiring connector: water sealed quick disconnect.  Mating connector is
  included.

  Wiring: Red for +5V.  Black for ground.  Blue for signal output.

I tested it out on the bench using an oscilloscope and multimeter and measured the following:

When no pressure is applied it is producing about 418mV. This seems correct based upon the above.
When I force some air into it using my mouth the voltage goes up as expected.
The resistance between 5V and GND is 42.7K ohm
The resistance between 5V and signal OUTPUT is 120K ohm
The resistance between GND and signal OUTPUT is 69K ohm

I connected the sensor signal wire to my LPC1768 micro-controller on P17 ( analog in ), sensor Red wire to +5V and the sensor ground wire directly to ground.

When I read the 12 bit AD convertor output I saw wildly varying output such as the following in the Pressure column:

Cycle   Level        Pressure
================================
[211]   W:[184]     F:[2200]
[212]   W:[184]     F:[2071]
[213]   W:[185]     F:[1279]
[214]   W:[184]     F:[418]
[215]   W:[184]     F:[1514]
[216]   W:[184]     F:[3002]
[217]   W:[185]     F:[1499]
[218]   W:[185]     F:[0]
[219]   W:[183]     F:[1430]
[220]   W:[184]     F:[2501]
[221]   W:[184]     F:[1965]
[222]   W:[185]     F:[1311]
[223]   W:[184]     F:[263]
[224]   W:[184]     F:[1509]
[225]   W:[183]     F:[3195]
[226]   W:[186]     F:[1518]
[227]   W:[184]     F:[74]
[228]   W:[185]     F:[1306]
[229]   W:[184]     F:[2037]
[230]   W:[184]     F:[2409]
[231]   W:[184]     F:[1478]
[232]   W:[184]     F:[30]
[233]   W:[184]     F:[1503]
[234]   W:[185]     F:[3254]
[235]   W:[184]     F:[1549]
[236]   W:[184]     F:[433]
[237]   W:[185]     F:[1025]
[238]   W:[184]     F:[1714]
[239]   W:[184]     F:[2691]
[240]   W:[185]     F:[1479]
[241]   W:[184]     F:[0]

I'm using the same software routine to read both the Level and Pressure column. The Level column is very stable unlike the Pressure column.

My questions are as follows:

If the sensor is supposed to output .5V with no pressure how is it that I'm reading 0?
Why such variations between each ADC reading?
Do I have to add some components to the circuit interface because of the resistance noted above in points 3,4 and 5 such as a unity gain buffer? If so, what op-amp would you recommend? Note that I'm not an electrical engineer, just a hobbyist new to op-amps.
Thanks Joe Hass for the unity gain buffer idea.

What about power supply filter capacitors? Should they be needed and if so have much?
Should I add pull-down or pull-up resistor?
Is it possible to get this to work or would I need to use a much more expensive item such a Honeywell industrial pressure sensor?

Note: This is both an electronics and software question. Right now I am working on the electrical interface.

Update: Things appear for the moment to have been solved. I had the sensor signal connected to the LPC1768 P18 which is shared as Analog In and Analog Out. The sensor signal is now connected to P17 ( Analog In only ). That change and adding a 0.1uF cap to filter the sensor output has made the output at 0 PSI appear correct. I just have to test it with an air compressor and certain PSI settings to ensure the ADC readings remain correct.


texts: Theoretical break frequency and bandwidth of notch filter

texts:
I'm trying to learn how to calculate the bandwidth and break frequency for the notch filter shown below. I was told that wye-delta and delta-wye transformation would be needed, but don't fully understand where to go.

Below is some of my work thus far for simplifying the circuit to get the transfer function
note: C1 and C2 represent the frequency transformed impedances of their equivalent capacitors; ie, C1 = 1/(1uF *s)
note 2: T-structures should be labeled \$\Pi\$-structures).

Taking the Wye-like Structure and Delta transforming the lower-wye, then combining the C2 impedance with the top impedance of the new delta structure, I was able to achieve the following (intermediate) transfer function:


texts: Understanding this LM317 LED Driver circuit

texts:
I came across this simple LED Driver circuit ( I am aware of the power losses but just wanted to understand its working) .

Now in a Voltage regulator configuration , ADJ is connected to a voltage divider which sets the voltage output at the OUT pin .

This image(below) is the regulator configuration .

Now in this image R2 is replaced by an LED(Which has very low resistance) and R1 is the control potentiometer which helps us control the brightness to the LED .

Can someone explain how exactly does the LED Driver circuit work ?
The part I get confused is the wire to the ADJ pin. Does it behave like a feedback of sorts to get a voltage on the o/p ?


texts: What's the theoretical efficiency curve of a series motor?

texts:
I'm making this post mostly to check things for another post I'll make (if I don't find any error up to this point).
I'm trying to calculate the efficiency for an ideal DC series motor as a function of the speed, without any load attached to it.
Once I'm considering it's ideal (in classical mechanics), then there's no friction and it will accelerate indefinitely for any given input voltage U. The mechanical output is going to be entirely converted into rotational kinetic energy at any moment.
The expressions I developed for the series motor are:
T = KtI²
Torque is proportional to the square of the current with a constant Kt
I = (U-Eb)/R
The current is equal to the resulting voltage (applied voltage minus back emf) divided by the total series resistance
Eb = KeNI
The back emf is proportional to the speed and the current (once it's the same for the field winding) with a constant Ke
Solving this the current and the torque will be:
I = U/(R+KeN)
T=KtU²/(R+KeN)²
The mechanical power (Pm), electrical power (Pe) and Efficiency (E) will be:
Pm=NKtU²/(R+KeN)²
Pe = U²/(R+KeN)
E=NKt/(R+KeN)
The efficiency varies only with the speed, and as N tends to infinity, the expression tends to E=Kt/Ke
I'm unsure of the meaning of this result.
I know that at least until the expression for efficiency the dimensional analysis checks, both sides of the fraction have the unit Ohm (N·m·s/C²), so the result is dimensionless as efficiency should be.
This also shows that the efficiency is independent of the applied voltage or the torque its exerting, the only variable in there is the speed.
Is this true for a situation with load?
I mean, if I find the equilibrium speed for a given load and applied voltage, then I can find the efficiency directly through that expression?


texts: Can one program an STM32H7 chip directly using an ST link/V2

texts:
I recently bought an STM32H7 chip, soldered onto a breakout board. I have been trying to program it using the ST-link/V2 using system workbench for STM32. I get the error: "Wrong device detected". The datasheets do not give me much information.

My question is: Is it possible to program the STM32H7 microcontroller directly, using the ST-link/V2?


texts: Why does my power bank switch off when I use it to charge a toy battery

texts:
I want to use a power bank to charge the battery of a toy car.
I used an old USB cable, connected the power lines only to a voltage step up circuit to step up the voltage from 5V to 8V, then connected the output of the circuit to the DC adapter interface to charge the toy (made sure I can measure the 8V at the adapter interface.)
The problem is, when I connect the setup to the car, the charging lamp is on for a few seconds then it goes off, when I disconnect the cable from the power bank and connect again, the same thing happens.
What could be the problem ? Should I use the data lines as well? Does the power bank rely on them?
Update : When I connect a shunt 1K ohm resistor, before connecting the adapter jack to the toy, the power bank remains on and I can see the 8V across the resistor.
When I plug in the jack, the power bank shuts off and I can only see 5.5V across the resistor (which is really weird for me as the connection is parallel)
Can you please help me what can the issue be ?


texts: Suggestions to interface a photodiode in the MHz range

texts:
The task at hand is to read the variations of incoming light at speeds up to 1 MHz, with some dynamic range capability (10-1000lx with 1% accuracy would suffice).

This is to be used in a device which measures lighting quality (flicker detection in light sources and backlights). Light flicker is usually in the kHz range, but we've measured an office CFL lighting that has some small 100 kHz "ripple". I take it that in order to analyze a 100 kHz signal to at least some degree, a 1 MHz sampling rate or more would be needed.

I have questions on both the analogue and the digital part of this :)

The analogue part of the question is how to interface the photodiode (SFH213). I've read that a transimpedance amplifier is the suggested path, but I need a programmable gain TIA to cater for the dynamic range. Making a TIA for a fixed gain seems doable, and there are even ICs for that, but I haven't found any programmable-gain TIA ICs (or I haven't searched well enough). Would it be a good idea to use a fixed TIA gain, tuned to the 1000lx illumination range, and then follow that with a good programmable voltage-gain amplifier to cover the 100lx and 10lx ranges? (Other ideas come to mind, but are probably stupid, e.g. a logarithmic amplifier there).

The digital part of the question is how to sample the resulting signal at 1 MHz. I've selected a dsPIC33FJ16GS502, which boasts a 4 MHz ADC sample rate. Is this actually attainable? Analyzing the signal on-the-fly would be of course impossible at 1 MHz, but I can use a sample-store-analyze approach there.


texts: The usage of chip topography and diagram(schematic)?

texts:
Are you an EE? Do you use TI Op-Amps? then you should know the answer of this question. probably that could be interesting for us.

If you take a look at the datasheet of TI(or a few other companies) Op-Amps you will come across with "chip topography" or "diagram(schematic)". for example:

Source

or:

Source

or for schematic:

Questions about the chip topography:

What is/are the usage of chip topography for an EE? because the many of information for the chip topography of a chip is mechanical while we are EE. that's interesting to me that you can see the chip topography of ICL7650 in the MAXIM datasheet but there is no schematic for it. I think the schematic is much more clear than the chip topography then why there is no schematic for it?
Have you had any experience to use chip topography in your design? what was that?
Why while there is a clear schematic, they put chip topography?

Questions about the schematic:

Personally I think there are everything that we need to use for designing our circuit then what's the usage of the schematic? (you can see everything that you need in)

Please tell me all things that we can catch from these stuff.

Thanks in advance


texts: Transient Response of AC Coupled Inverting Amplifier

texts:
The circuit below is from this App Note.
The document describes:

The capacitors C1 and C2 need to fully charge for the circuit to
function properly. The definition of fully charged can vary depending
on the accuracy required for the circuit. If we assume a 12 bit system
the time required to fully charge the input capacitors is given below.
For 12 bit settling
τ1 = R1C1 = (1kΩ)(10μF) = 0.01s
T1 = ln(2^N)τ1 = ln(2^12) (0.01s) = 0.083s

In the second picture, when the switch is open R1 is about 63k. I want to understand better what really happens here when I use this circuit connected to an ADC. In my case I have a 12 bits ADC, so:

τ1 = R1C1 = (63kΩ)(10μF) = 630ms
T1 = ln(2^N)τ1 = ln(2^12) (620 ms) = 5.24s

5.24s is way too long. Does this mean I wouldn't sample the signal correctly until the capacitor charges in ~5s?


texts: Switching on DC to AC converter large voltage drop

texts: [![Current pulse at source of PMOS][1]][1][![Test across inductor with 470ohm at gate of PMOS][2]][2]I am trying to switch on a DC to AC converter, the load for the primary side of the circuit (where the DMM is measuring across) is a transformer (which I have unfortunately not picked out yet due to being unable to produce a working DC to AC converter, and as a note the only concern for frequency and current I have is to make sure components aren't getting too hot, or damaged, also, ideally I would like a transformer on the scale of 5 inches and under which usually means higher frequency, aside from that frequency and current can vary) and I am trying to step up voltage to upwards of around 390VDC which will be delivered to the load which in my case is a cathode to create the electric field. I just want to create an electric field at the load of the secondary side of the circuit to achieve phase transition in Bose-Einstein Condensate by increasing the voltage instead of lowering the temperature. The rectifier portion seems to be working well (tested separately with AC voltage applied) but I am having trouble with the DC to AC converter portion. The switching event works as expected which means I have approximately 12VDC going into my LM555. However when I measure after the DC to AC converter there's a result of <1VAC. Am I doing something wrong here circuit wise or the way I am measuring? Why such the large voltage drop? R1 = 10kohm, R2 = 100kohm, R3 = 100kohm (initially).


texts:
I understand that the NTSC TV signal is 30hz and PAL is 25hz, but if NTSC and PAL are TV signal standards how could they affect display rate(Hz) for input devices e.g. when you connected and old game console (signal goes from console to TV). If I am not wrong analog input was the same in USA and Europe. Sow how come that there were consoles(or games) for NTSC and PAL ?

I know it may not be entirely electrical question but since signal coding is closely related to electronics I decided to post it here.


texts: Supply voltage of LM741 with Virtual Ground

texts:
I'm looking for a way to feed LM741 with a battery.
I found this example that uses the TLE2425 to create a virtual ground of 2.5V (in the original example was used opamp TLC272):

I simulated this circuit in Proteus and worked perfectly. But I do not understand how this works, because the voltage supply of LM741 is ± 5V to ± 22V, and this circuit feeding the LM741 with + 2.5v (+ Vcc) and -2.5V (-Vcc).


texts: Voltage controlled versus current controlled Inverter

texts:
I would like to ask about the voltage and current controlled inverters.

In a current controlled inverter, the control target is the output current and they provide high quality current to the grid.

In a voltage controlled inverter, the controlled target is the output voltage. Thus they can support the grid voltage.

I would like to ask if there is another main difference between these two control methods and should I choose the one over the other.


texts:
First of all I'm not sure if this is the correct site for this question but:

I am trying to fix a head phone jack for my headset with a TRRS headphone replacement. This is the connections of the headphone jack:

     ┌-------┐
     | ┌-----+-┐
     | | ┌---+-+-┐
     | | | ┌-+-+-+-┐
     | | | | | | | |
tip (=|=|=|=☐=|=|=|= to headset
     1 2 3 4 3 2 1 4
     T R R S

And the colors I have on the headset are white, green, red, and blue. The white wire is the thickest of the four wires, while the green, red, and blue wires are thin with a fabric-like insulation covering each wire.

I was hoping to take apart the original headphone jack and finding out where each color wire goes, but i lost it. So, my question is, which wires go where?


texts: Will this zero-cross detection circuit work?

texts:
I have a 10W SMPS circuit powering a home appliance like this:

I need to extract a zero-crossing pulse from this circuit which would then be fed to a micro-controller. To this end, I am considering the following modification to the circuit:

Specifically, I have added an opto-coupler PC817 whose input LED would be driven from the rectified ~340V (0 to peak) through R16 (330k, 1/2W resistor). The maximum input current to the opto-coupler would thus be ~1mA. Considering the CTR to be 0.8, from the datasheet, the collector current would be ~0.8mA. Accordingly, I am considering a 33k resistor for R17. Have also added D10 (1N4007) to isolate it from the smoothing capacitor.

Are the calculations correct? Will the circuit work?
Is it okay to drive the opto-coupler LED from ~340V? Would it damage the components or make the circuit less reliable?
How to estimate and minimize the pulse width at the zero-cross output so that it is closer to the zero-crossing?


texts: Digitally-controlled 0-10A constant current source for driving LEDs

texts:
I'm looking to build a circuit to drive single high-power LEDs. The circuit will be controlled from a series of TTL pins: one for enable/disable, and ~4-6 to set brightness via current.

The LEDs will be driven continuously at up to 1A (at 2 - 3.5V), and pulsed at higher/over-spec currents of up to ~10A. Pulses will be in the order of 1-100 ms, and will be separated by a few seconds. Rise and fall times don't need to be ultra-fast, but should be less than 500 us. PWM could potentially be used within the 0-1A regime, but I'll definitely need some sort of current control to reach the higher currents.

There seem to be plenty of commercial LED driver ICs that do these sorts of things, but I haven't been able to find any that can control the currents I'll be using. In addition to that, I'm not sure what the best way is to control current using TTL: maybe through a DAC to an op-amp to a power transistor? I'm not sure what the best way to approach this efficiently is.

I'm planning on using an old computer PSU to power the whole circuit, through the 5V or 10V rail. If there are any obvious problems with this, or better options, I'd love to hear about them.

Thank you! Any suggestions will be greatly appreciated.

(A disclaimer: I have a good understanding of the fundamentals of electronics, but don't have any real EE experience. So, I understand what different transistors or capacitors do theoretically, but have no intuitive grasp of which components are the best solutions for which tasks in reality.)

Update 22/3

Having though about this a bit more, I think I actually need two separate circuits for two different tasks. One will simply act as a switch to individually address four LEDs in a string powered by a standard CC power supply (I have a box of LuxDrive PowerPucks available for this). Something like the following (ignore the +5V note; it's a constant current rail, but my freeware circuit drawing software doesn't seem to support that):

but with four of the MOSFET-switched blocks chained in series. Five TTL controls as inputs, giving one enable/disable switch + selective shorting out of each of the four LEDs. Vishay SIA406-DJ MOSFETs seem like they'd work here; I'm not sure if the diodes are even necessary, but if so I don't imagine they'd nee to be anything special.

My first question here: As the TTL signals will be coming from an extremely expensive instrument, I'd like to use opto-isolators to protect it. I've never used these before (and am only conceptually familiar with them): taking the circuit shown above, can I simply put opto-isolators between the TTL input and the MOSFETs' gates? Secondly, how should I best ground these? The controlling instrument has its own internal ground; do I need to somehow wire into that, or can I run wires directly from the TTL out pins to an external grounded PCB?

The second board (the original proposal) will supply a single LED channel current with digitally-controlled current in the range 0-1A for CW illumination, and 1-10A for pulses. For this, I intend to use the analogue dimming ability of the Infineon ILD4001 together with a DAC to vary the current, with MOSFET switching as before.

Physical switch used to change between 1A (through \$R_1\$) and 10A (through \$R_2\$) control

The ILD4001 uses a single EN input for on/off, PWM, and analogue control of current output. Analogue dimming is achieved by setting \$V_{in} = 0.5 \sim 2.4 V\$, with a largely linear relationship between 1.0 V (25% current) and 2.1 V (90% current). To achieve this, I'd like to feed 4 bits of input through a DAC, with the whole setup switched by a 5th bit, like so:

...with the output fed into to the EN pin of the driver circuit.
Again, all five control bits need to be opto-isolated from the signal source.


texts: I'm taking a look right now at page 215 of Verilog HDL: A Guide to Digital Design and Synthesis by Samir Palnitkar, where it's talking about Verilog primitives to represent MOSFETs. It says, "Thus, the nmos switch conducts when its control signal is 1. If control signal is 0, the output assumes a high impedance value." What does that mean, "a high impedance value"?


texts: I bought a few COB lights from Harbor Freight, they look like light switches. I would like to hook them up to a wall mount power supply, I think they are wired in series. Also, I would like any information on COB lights and how to tell what voltage, watts  and amps COB lights are and how to tell? Is there a website that shows this? I bought on COB light strip but don't know volts, watts nor amps, how can I tell?


texts:
for a project I'm looking for a charging solution to charge a lipo battery, while at the same time being able to power a microcontroller with 3.3v.

For that purpose, I bought a few TP4056 boards that also include a DW01A and a FS8205A and should be able to provide charging and protection.

The schema of this circuit is:

I've been experimenting with these 2 batteries:

One is a 3.7v 1200mAh battery, the other is a CN18650 9800mAh battery (Or at least, that's what the printed on them.

Charging them seems to work fine, after a while the green led on the TP4056 lights up, indicating that charging is done.

At full charge, both batteries give just over 4v. Since my microcontroller requires 3.3v, I used a XC6203P332PR (datasheet) to regulate the voltage. I hooked the Vin up to the OUT+ of the TP4056 circuit, Vss (ground) to OUT- .

I expected OUT+ and OUT- to give the same voltage as the B+ and B-, but unfortunately, it doesn't. With the 1200mAh, I only get about 0.7v on OUT+ and OUT-, with the 9800mAh, I see erratic behavior, sometimes it geve the proper output voltage, but a lot of times, I also only get 0.7v out of it.

I can't quite figure out what's going wrong. I've tried multiple TP4056 boards and multiple batteries, but did not get a consistent figure. Googling around, I find mixed information about the TP4056, apparently there are also cloned versions of this chip around.

I was wondering if anyone knows the cause of my problem, am I doening something obviously wrong, or is the TP4056 just not the right way to go? and if not, are there any other suitable (and preferably affordable) solutions around?


texts:
I'm just starting up with IMU's and I really want to work on my own flight controller, but a question always hits my mind and I am not able to find answer anywhere, so I'm here.

Will multiple IMUs will help improving stability of a quadcopter? averaging out the values of all the multiple IMUs should reduce the drift, which is a function of time, but I have no experience with IMUs and just cant figure out about the amount of error correction by adding one extra IMU, will it be just additive? or Exponential?

This question was also posted on the Robotics Stack Exchange site.


texts:
I have pic program and on the circuit I have this:

I understood that it was a boost converter manipulated by the PIC in order to generate the voltage of 13V (VPP btw VDD = 5V) necessary for the programming of the PIC. But I do not understand why there are 2 capacitors that are not even of the same order of magnitude ...
It's just to have the right capacity by summing the two or ...?

Why are there 2 capacitors that don't have the same order of magnitude?


texts: Will it work? 12V power off delay for embedded computer

texts:
A simple question, will it work as described?

Description:

Circuit is intended to immediately power on both a 5v and 3.3v supply to an embedded computer and other peripheral devices regulated with LM317 adjustable voltage regulators.  Once the computer is powered on, it can switch from the constant supply input power over to the 'UPS' or 'Buffered' power by high-side switching the 12V incoming power with a 3.3V output (see transistors Q1 and Q2).

At that point the device maintains operation with that power and if incoming power is lost all the peripheral devices lose power AND an input to the embedded computer goes low signaling that it needs to finish writing files and begin shutting down.  At this point it is operating off of capacitor C1.  Once it gets far enough in the shutdown process, it drops out it's output and then power to the device is killed.  This is necessary so that if power is re-applied the computer knows to startup, otherwise it would need to drain the capacitor down and would have a required minimum "drain down" time that would be undesirable.

My biggest 3 questions with this circuit are:

1) Is the transistor switching correct?  I had to look into how to high-side switch a higher voltage by using the PNP and NPN transistors in together.

2) Is R12 necessary?  This is a 'precharge' resistor.  I deal a lot with 480V drives for work all of them have pre-charge resistors to reduce inrush current.  The idea is in the first 30 seconds while the computer is booting up before it turns on the GPO, the capacitor can be pre-charged at a low current before it is supplied full 12V.

3) The size of capacitor is definitely questionable because it's not clear at all how much time I need and what the current draw is going to be.  I figure I need a minimum of 2-3 seconds above 5V to finish writing the files, and current draw is going to be around ~500mA @ 5V.  But right now until I've got some measurements I'm taking just a shot in the dark with 500uF.

Thanks!

Thanks for the feedback.  You're right about the typo, I meant R13, not R12.  But I disagree it was only an inline resistor, there is definitely a clear path to the top of Q2 through D9.  However, you're totally right that the diagram was hard to read, so here's a simpler version (I hope):

Also, you did answer my question about the necessity of the precharge resistor.  Due to the low voltage, I was hoping it wasn't necessary.  In that case we can make things much prettier, like so:

Now, regarding the use of N3904/6 transistors, would the 2N2222 and 2N2907 be more appropriate?

Thanks


texts: For production boards, is a buffer IC best to translate single unidirectional 3.3v to 5v logic without inversion?

texts:
I've read plenty of advice on how to deal with 5v <-> 3v logic translation and there seems to be a ton of methods, some of which I'm clear on and some I'm not.  Most of the material is geared around things like Arduino, etc... one-off hobbiest solutions that don't necessarily translate well to volume production for cost, pcb real-estate or reliability reasons.

So specifically for production at volume, what would be the best way to handle a single unidirectional 3.3v microprocessor output (this case it is a STM32F205) to a 5v device (this case it is an RGB LED driver with one-wire control) without inversion?  My guess is a dedicated buffer IC, but I don't really know.

My 5V device requires 0.7*5=3.5V for logic high and 0.3*5=1.5V for logic low.

My options appear to be:

Just chance a direct connection.  I put this here for completeness sake, because I think it would not be wise for production.  There is anecdotal evidence (forum posts) suggesting the particular device can operate at 3.3V despite the datasheet info.
I've been told a "simple pull-up resistor of 4.7k" should do the trick, however I've not found any discussions showing a single-resistor solution, so if anyone could explain this (preferably with a schematic) I'd appreciate it.  This solution is somewhat vaguely mentioned in an answer here.
That same answer also mentions a couple of diodes and a resistor, although this method is discussed here too with the article's author later stating in comments that he's not thrilled with the results.
A MC74VHC1GT125, which is a dedicated IC built for the job.  At a volume cost of roughly $0.06 to $0.07 it certainly isn't a cost issue (although % wise that is far above the other methods) but I wonder... is it the right way to go?  With this options, I have a couple "sub-questions":

I'm a little unclear on what purpose OE service.  When would you want it in Hi-Z? I just tie that to GND, right?
I've been unable to find any alternatives to this piece which specifically mention 5v to 3.3v translation, but any non-inverting buffer should do the trick, correct?  Diodes Inc 74AHCT1G125, for example?


texts:
I am working on a design where I need to amplify a small ac signal (a few μv, 1 Mhz) with a gain of 30 to 40, while introducing as little noise as possible. The input is driven by another op amp, so a high input impedance is not a requirement.

Currently I am using an op amp configured as non inverting amplifier. Even if the high input impedance is not required, the physical separation between input and output kind of makes me feel comfortable.

However when searching online I see a lot of examples where inverting amplifier configurations are used in similar situations, which made me wonder whether it might be advantageous to switch to an inverting design.

After some research I still could not find any particular reason why I might use an inverting amplifier in this scenario. Neither do I need an amplification of less than 1, nor a summing amplifier, as mentioned in answers to similar questions (1, 2).

So is there any particular reason why I would use an inverting amplifier if I am just amplifying a voltage with a gain of more than 1 (maybe considering noise, stability or other issues)?

EDIT:
Just to clarify, I am talking about following op amp configurations:

Non inverting amplifier (left) and inverting amplifier (right):


texts: How can I send data to the arduino from the computer? I'm thinking sort of a prompt on the command line and some commands like "led1 on". Then, the arduino would process that and light up a certain led.


texts: Interfacing with RAM from a PC, e.g. SDRAM / DDR, to a microcontroller

texts:
I'm looking into interfacing standard PC form-factor SDRAM or DDR sticks to a microcontroller, but I can't find any definitive details on how they work in terms of how the bus works. I guess it's similar to how any standard SPI or I²C interface works - send some instructions to the device, then read back some results until a particular pin state is met. Except in this case the data and address buses are parallel instead of serial.

I have three related questions on the topic:

What interface does standard PC memory, e.g. SDRAM or DDR, run on? I remember reading something about JEDEC being responsible for the spec, but I can't find any specific details. I'd like to use DDR (or DDR2) since it's cheaper right now, but I'll settle for SDRAM.
Can standard PC memory be bought down to more "comfortable" clock speeds? The standard bus speeds for these things tend to be around 133MHz, but I'm hoping to run them at less than 1MHz. My understanding is that SDRAM wait for clock edges before responding to commands, so a low clock frequency should result in it being manageable by a microcontroller.
What's the name of the physical interface? I tried looking on Farnell for sockets for such memory devices, but I only found some really tiny pitch surface-mount stuff. I could probably build my own through-hole version if I spent long enough, but I'd prefer to just buy one pre-built.


texts: Why Peukert's law is always ignored in battery(lead Acid) guides available on Internet?

texts:
I am doing battery calculations for off-grid solar panel. I don't get that why battery guides on Internet always ignore Peukert's Law for batteries of solar panel. I want to have good approximations not perfect. So, don't answer too complex please.

I want to know

What AH battery use
What is its charging time
Discharging time

If I have a 1KW load and I want to have its backup for 3 hours. That makes energy 3KWH. That means I need to generate this energy. Furthermore, 1 KW requires 4.54 current for a single phase at homes in Pakistan (220 AC at 50 Hz). This current can also be called discharging current of battery.

Id = 1000/220
Id = 4.54 A

Battery to use:

That means we require

AH = Id * Battery voltage
Let's take it 12 V
AH =   4.54 * 12
AH = 54.48

We should have DOD 50%, so that our battery drains only 50% and it gets the chance to charge again and doesn't go ever below 5o%. Doing so, enhances the  battery life.

AH = 54.58/0.5
AH = 109.16

Is it economical to use such a huge battery for only 1 KW load?

Discharging time:

Note that batteries come with 20 HR (hour rate). That means a battery shows its mentioned capacity if discharged in 20 hours. Otherwise so many losses occur and decreases the battery capacity. So here comes a complex pukerts formula.

where k=pukers number. But batteries don't come with pukerts no. Do they? I never ever saw written pukerts number written on any battery. Guides say that its usually between 1.1 to 1.4. But 1.1 and 1.4 makes a huge difference in calculations.

Anyway, let's choose k=1.4

It tells us that when:

C=54.48
H=20
I=4.54
then t=9.78 hours

and when C=109.16 AH
then t=25.88 hours.

I feel like I have used extra AH battery because I dont need backup for 26 hours. I need for 3 hours only.

Charging time:

Charging current should be 10% of the battery capacity. Therefore, 1/10th of 109.16 is 10.916 A.

Charging current should be 10.916 A and it will take t=109.16/10.916=10 hours to charge?

Please improve my calculations where lackings are. And correct me where I am wrong.


texts: Why are the charge and discharge rate of Lihium Polymer Batteries different?

texts:
I have a 3S 1.3MAH Lithium Polymer battery with a 25C discharge rate, and a 5C charge rate.From what i know, the discharge rate is the rate at which the battery can be safely ischarged( i.e how many amps it can provide saafely) while the charge rate is simply the rate at which it can be charge. Therefore for my battery, it can provide 25 x 1.3A -> 32.5A and can be charged at 5 x 1.3A -> 6.5A.

However, if the battery can be discharged at 25C, shouldn't it also be able to be charged at 25C? Why does it have different charge rates for discharging and charging when i should be able to pump in "energy" as fast as i can draw it out?


texts: Is it necessary to write all MSP430 FLASH writing code should be run from RAM?

texts:
I am writing some device parameters to non volatile flash memory of msp430f2619 controller.
Sample code shows that function writing to flash should be copied to RAM in initialization section.

But I am using this function to write into dedicated few of the Flash segment. ( Actually I am writing to Information memory segment B )

So is it really necessary to copy this code in RAM.

I am running low on RAM and by freeing this memory for storing flash write function I can use it for my application.


texts: Controlling simple output with a button and a relay

texts:
Just a side-note, I am a complete beginner when it comes to circuitry.
I am attempting to control a garage door controller with a relay powered and controlled by a Raspberry Pi. The garage door already is controlled by a button with some simple 2-core wire.
How can I get both the button and the relay to trigger a signal to my garage door?
I guess what I am trying to create here is an OR gate.
Anyways, I hope this is enough information.


texts:
I'm building a DIY project with a Rapberry Pi.
I tried to cut down the connections to the ones I think might be involved in a certain behavior I'd like to understand.

What I have:

a 12V power supply
a UBEC that is powering the RPi
a small DIY board with connection for some sensors, an LCD and some fans

The 12V arrives on the board through a TIP120, switched with a GPIO pin from the RPi. From the RPi itself, I'm using a VGA cable to bring many GPIO pins (for various purposes) and the 5V up to the DIY board; but not the RPi's GND: since it should be the same GND "shared" between the power supply and the UBEC through the RPi, I thought I could save a wire and use the GND from the 12V wire. This had the advantage of shutting down also all the other 5V stuff attached to the board when I cut the 12V off from the TIP120.

pdf download

The behavior I don't clearly understand is this: when the GPIO pin in the schematic is LOW, and no current flows through the TIP120, the 5V part of the DIY board is also shut down, but the fans continue to spin at a very low speed, and in fact probing with a meter, there are ~6V across them.

I think that the circuit is being closed via the 5V wire through the RPi, thus having the 6V across the fans (12V are slightly lower, about 11V; and 11V - 5V = 6V).

Is this correct?

Then, if I disconnect the "common GND" and bring a wire from the RPi's GND to the 5V section of the board (connecting the two "X" in the schematic) it clearly stays always ON and also I'm able to completely shut down the 12V fans (in addition, I'm surprised that all PWM signals from the RPi to the fans, regulating their speed, continue to work).

(Sorry for the simple circuit diagram, I hope there are not too many mistakes, especially about notations - I do this for fun and I'm not an expert)


texts: Voltage rating vs. power rating of a resistor

texts:
My question may sound very basic, but I am very confused by the difference between the voltage and power ratings of a resistor.

Vishay's document says:

  Rated Power

  The maximum amount of power that can be continuously loaded to a resistor at
  a rated ambient temperature. Network
  and array products have both rated power per package as well as per element.

  Rated Voltage

  The maximum value of DC voltage or AC voltage (rms) capable of being applied continuously to resistors at the rated
      ambient temperature.

I read this datasheet for a 27Ω, 0.2W resistor. Page 3 of the datasheet shows this formula:

\$ RCWV = \sqrt{P\times R}\$

  Where RCWV = Rated DC or RMS AC continous working voltage at
  commercial-line frequency and waveform(volt)

  P = power rating (watt)

  R = nominal resistance (ohm)

The above 27Ω resistor on the link has 50V voltage rating and 0.2W power rating, then I place the values into the provided formula

\$ RCWV = \sqrt{0.2\text{W} \times 27\Omega}=2.32V\$

Could anyone explain me why the voltage rating is 50V, not 2.32V?

When I want to calculate the maximum current that the resistor can stand using the power rating of the resistor (0.2W):

\$ P=I^2 \times R \$

\$ I = \sqrt{\dfrac{P}{R}} = \sqrt{\dfrac{0.2\text{W}}{27\Omega}} = 86\text{mA}\$

If I use the voltage rating:

\$ I = \dfrac{V}{R} = \dfrac{50\text{V}}{27\Omega} = 1.85\text{A}\$

By looking at these results, I should use the power rating, right?


texts:
Consider this SW-104T thermal fuse. It has a current rating of 10A.

Does this mean that in addition to its thermal fuse capabilities (blowing at a certain temperature profile), it also behaves as a 10A fuse, and will blow safely when current exceeds 10A (within the parameters of its delay time, maximum voltage, etc)? Or does it just mean that it is specified to operate properly at 10A and below, and if you exceed that it is now out of spec and anything may happen?


texts: Understand the Primary/Secondary/Subordinate Bus number in PCI/PCIe Bridge

texts:
I am new to the PCIe world.

I am learning the enumeration and configuration of PCIe hierarchy.

Some quote from here:

  For PCI-PCI bridges to pass PCI I/O, PCI Memory or PCI Configuration
  address space reads and writes across them, they need to know the
  following:

  Primary Bus Number The bus number immediately upstream of the PCI-PCI Bridge,

  Secondary Bus Number The bus number immediately downstream of the PCI-PCI Bridge,

  Subordinate Bus Number The highest bus number of all of the busses that can be reached downstream of the bridge.

My understandings are:

The Secondary/Subordinate bus numbers give the range of specific PCI bridge's downstream buse numbers.
And these 3 bus numbers together serve kind of like a routing table since PCIe hierarchy is essentially a network.
Once the enumeration process finished configuring, software can rely on the Bus/Device/Function address to access devices. All the underlying routing of packet are purely by hardware with no software interference.

Am I right on these? Thanks.


texts: TRIAC Circuit triggered due to interference

texts:
I have a small circuit designed to switch on the lights in my room using a wifi-enabled microcontroller Particle Photon. The circuit is based on an opto-triac and TRIAC setup where the microcontroller triggers opto which triggers the TRIAC to switch on or off.

I installed 4 of them in my house, 1 in my living room and 1 in my bedroom (both incandescent bulbs) , 1 in the kitchen and one in the bathroom (both use neon based flourescent lamps).

I also have a push button wired to the Microcontroller to enable physical switching for the lamps along side the wifi.

The problem
When i switch on the lights in the kitchen, the lights in the bathroom and my bedroom go up as well.

Notes :
1. My boards are connected to a cloud service by Particle, where i can monitor (remotely from a laptop) if a voltage was applied to a certain pin.
2.Every board of mine has a powersupply (5V 1A) output the powers the board. This power supply takes in Mains (220V AC and Neutral directly from the wall)
3. My board takes in 5V from the supply and is connected to the Mains, and Lamp to switch on/off

Trials and Conclusions
1. I thought it was a software issue, so i disconnected the internet from the boards and tried it again, again it happened, therefore this has to be a HW problem.
2. I immediately went to think that the neon is somehow cause some back-emf or something and messing up my gear, i disconnected the power supply and powered my board through a portable mobile charger , still happened again, the lights in the other rooms went on.
3. I disconnected my board from the wall (Yes , my board is now completely wireless), just to see if the pins would be triggered (i can see this through my web service). and YES, when i switch on lights in the kitchen, my WIRELESS board in the bathroom registers a voltage on my pin. Now keep in mind i deliberatley set my (now) wireless board very close to the naked wires in the wall that trigger the lamp, when i take it farther away, it doesn't register that voltage.

One possibility now ... Electromagnetic Interference.

Q1. Is my assesment correct?
Q2. How to resolve this issue?

This is my circuit :

This is the current setup, it's completely sloppy and potentially unsafe i know but i'm a professional at this , no worries

The blinking thing is the microcontroller on my board, the green board is the power supply.

I know this is rather complicated , any questions required to answer this i'm fully prepared to provide details. ANY HELP IS GREATLY APPRECIATED.


texts:
According to STM32F407 reference manual page 313, memory to memory mode in DMA is a mode that doesn't need any triggering request from a peripheral and it will happen just after the stream enable bit is set.  (also we know from the reference that only the DMA2 could handle memory to memory data transfer) :

So the question is for a transfer between two integer array defined in the memory area, which stream of DMA2 must be enabled and which channel of this stream must be used to have a DMA transfer without any peripheral triggering and only when enabling the DMA stream?

In fact what i want is sending some data from a buffer array in the memory area to a GPIO output data register. As is said what i expect to happens is when stream is enabled the transaction just happens but the result was not what i expected and no data is sent to that GPIO output data register. I want to use memory to memory DMA mode  because it doesn't need any extra triggering


texts: Designing a Li-Ion equivalent USB powered circuit

texts:
I'm trying to replace a Li-Ion battery powering a device with a USB cord directly connected to my PC.

Which design parameters should I consider in choosing the right components?
I only took in consideration voltage and (estimated) current draw.

The device uses a single cell 3.7V battery and, since I think that the full charge voltage should be 4.2V and the end-of-discharge voltage should be 3V, I'm going to supply the device with 3.3V voltage.

The way I'm going to achieve that is by a Linear Voltage Regulator: which to choose to best emulate the Li-Ion battery? Is an AMS1117 good or should I choose something different? Will some component damage my PC?

Current draw should be around 50 mA.


texts: Wireless communication between two arduino boards

texts:
I am working on a project where I need to wirelessly communicate two arduino boards. One arduino will be used as a beacon to relay info for others. The one relaying information will have to be burried in ground say 6 inches beneath surface level. The distance between two boards cane be around 10 feet. I learned arduino Wireless SD Shield is a way to establish wireless communication but it also says that communication is going to be in line of sight. But in my matter, there is no line of site. The setup has to be one point to many points as the beacon will send information to many points.

How I do that? Can someone give link to some latest tutorial for such setup.


texts:
So I'm doing my Circuits homework and I got to the circuit above.

Obviously \$i_4\$ would have to be 1A, because of KCL.  However going further along, I can't find a way to make \$i_3\$ positive!

I don't want you guys doing my homework for me (I need to learn!) but I was just wondering if it would be possible for \$i_3\$ to be -1A?  The far-left element needs another ampere from somewhere.


texts: We know that voltage follower will have a nonzero output current. How do I solve for this value? Let's say I am using an LM358 op amp to implement the buffer (unloaded), do I just use the Output Current given in the datasheet? Or do I consider other factors here?


texts: As "RS-232" is a Protocol/Standard, "DB-9" is a type of Connector, Is RS-232 Cable a valid term? Or is there any proper name for that? "Serial Cable" maybe!


texts: What is the purpose of cylinder "second power bricks" on cords?

texts:
I have noticed a large number of power cords that have a PSU built into them also have a second brick on them. What is the purpose of this "second power brick"?

Example, Xbox 360 Power Adapter:

I dug through my old electronics and found other devices that have the cylinder  add on, as well as an USB type A to Micro USB adapter that also had the cylinder. This suggests that the cylinder might not be exclusive to AC to DC power adapters.

USB type A to Micro USB adapter:


texts:
I know that stepper motor structure is more different. I have MSP430 launchpad.
I know that I m guessing that I can't solder it to pins. Can I use it with breadboard, uln2003a and a potentiometer. This stuff is suitable with launchpad
I m going to use unipolar stepper motor.


texts:
I've got an obsolete part in a design (SY100S839VZG) that is being used to take a single 100MHz clk and divide it down into two PECL p/n pairs.

For the life of me, I cannot seem to find a single clock divider out there that supports /5 that isn't obsolete or about to be. Did the clocking industry collectively decide to longer support that, or am I just missing something obvious?

I've checked Silicon Labs, Texas Instruments, Analog Devices, ON Semiconductor, and Renesas, along with Digikey/Mouser/etc.

Any ideas or suggestions on where to go from here?


texts: Treat valve heater as resistive or constant current?

texts:
I want to run a 13V(300mA) valve filament from a 6,3VAC transformer, using a voltage doubler(Greinacher circuit).

I am using PSUD2 to simulate the circuit, Which gives me 2 options for the load, either constant current or resistive. Using either I was able to create a source with ~13V RMS output, with 2,2mF capacitances(Which I could get relatively cheaply as bipolar electrolytic).

I would like to know if this could work, because while nominally the voltage doubler should have ~18V output, because of the strong load, the RMS voltage stays 13V. And this already makes some assumptions: What is the series resistance of bipolar electrolytic capacitors of high value(2.2mF)like these? (I assumed 500mOhm).

I expect reality to be different, so I guess I'll have to measure the voltage and correct with some series resistance or voltage divider, but I'd like to know if its possible at all, and how would I go about creating it?

Also is the heater a resistive or a constant-current source? If neither, which one approximates it better?

What other option do I have if any for using this 6,3VAC tap to power the 13V PCL86 tube(Which sadly doesn't have a center filament tap)?

EDIT:
I had went on with the voltage doubler, and I got exactly 13V for the heater without any problems. The simulators results were very precise.


texts:
I have a N-Channel MOSFET gate connected to a Teensy 3.6 analog pwm pin with the intention of setting the duty cycle on the output of the pin to control the switching of the MOSFET. For reference this is 500 Hz I believe although it is irrelevant.

I have noticed that while the MOSFET works as expected and has low resistance (micro-ohms) when the load voltage (6V) is off as soon as the power supply (12V stepped down to 6V using a buck converter) is turned on the resistance shoots up to its off state. The load is a only 4 ohm resistive heater.

Simple schematic to get the gist of my setup

The 5V input to the gate is from a level shifter connecting the pin of the Teensy to the MOSFET's gate. There is a 10K Ohm resistor in parallel between ground and the gate and the voltage to the heater is 6V.

I am new to electronics and any help would be much appreciated.


texts: Getting most power from low voltage solar powers, each different angle

texts:
I have a specific problem. I have 10 small solar panels, each max 5.5V and 100mW power. Each one is at a different angle. I want to get the most power out of it. Cost is not really a problem, but I do appreciate a simple design.
I was thinking of a MPPT controller with an ideal diode at the end for each of the panels, then connecting all of them in parallel. I guess that would work, but worried about the overhead of the MPPT controller for such small voltage and power.
Another solution I had in mind is getting off the shelve boost dc converters to bring all the cells to the same voltage, then again ideal diode, and parallel. But I think that would be very inefficient.
Any other ideas? Thanks!


texts:
I'm trying to use cansniffer and candump to read the CAN bus data in my car with a Raspberry Pi and the PiCAN 2 board, but I have run into a weird issue I can't explain.

Situation:

I've located the CAN-H and CAN-L wires in the car. I stripped part of the wires and used wires with an alligator clips on both ends to clamp to the stripped part. On the PiCAN board I attached wires to the CAN-H and CAN-L ports, each wire is stripped at the end, and also connected with alligator clamps.

The problem:

I only see data from candump / cansniffer when I take off one of the clamps and 'rub' the wire against the clamp. Which seems really weird, and I have never experienced anything like this. Are there some tips that I can try?

I have tried using just wires, different wire gauge, but the problem stays.


texts: How to measure the battery voltage while charging

texts:
I am designing a battery charger with 48 volt 10 amp output. I am controlling the buck converter pwm  using PIC controller. During charging the battery's current and voltage have to be constantly monitored in order to supervise charging. I am going to use external ADCs for monitoring the charging voltage and current. SO I want to know when and how  to measure the battery voltage and charging current during charging. Is there any controller or sensing device available?
 How can I measure it while charging because at a time of charging ??


texts: Zener diode voltage limiter for Intrinsicaly safe application

texts:
I am designing a product that should meet ATEX requirements (Intrinsically safe design). Part of the design is a voltage limiter (overvoltage limit of buck-boost converter). Typically Zener diode is the only component acceptable by ATEX standard as a safety voltage limiter (no other circuit composed of more components would be accepted). I am selecting the Zener diode which should meet the following requirements:

min. total power dissipation 1.5W
Nominal zener voltage below 4.3V
Reverse current at 3V below 100uA (or close to this number)

I can not find a suitable component. Searching is difficult as the reverse current is often specified very generally (eg. 5uA @ 1V). My current choice was 1SMB5916BT3G but measurement shows that the leakage current is around 2mA at 3V.
Would anybody be able to advise? Maybe try to search for some TVS diodes? Not sure if this would be accepted by the certification authority.


texts:
I've got a bluetooth module from dx and connected it to my Arduino UNO R3. It was working just perfect but after a couple of hours of work it just stopped sending data.

I think, the problem is with RX,TX pins voltage. Arduino sends 5v on TX pin, but I can't figure out, which voltage does BT board receive on it's RX. I think, I've burnt this BT and don't want to do the same with the new one.

There were no docs with the board. There is a doc only for the main board(not for the breadboard), and it says, it operates with 3.3V levels of RX and TX pins. All over the net people say, that the breadboard from DX works with 5 volts too... But I've the negative experience...

Any help appreciated!


texts:
The current in photo diode because of generation rate G and depletion width W is given as qGW (neglecting diffusion currents).

When the light is incident on the diode excess carriers are generated in depletion region in pairs and these are swept to respective P and N regions.

If the above is true, then why we are not taking current because of both holes and electrons i.e. current should be 2qGW.


texts: Reducing bandwidth of op amp to eliminate op amp parasitic oscillation

texts:
I am using few op amps to amplify a signal coming from a FGEN. My signal from FGEN is around 500Khz-7.5Mhz. Now regardless of the supply, even when the FGEN is disconnected and power the op amp using DC supply the op amp starts oscillating.
I read here in StackExchange that by increasing the feedback resistor value or in other words increasing the op amp gain will reduce the bandwidth of the op amp and thus remove those unwanted oscillation. So today I changed the feedback resistors from 1k to 20K and then the oscillations were gone and when i turned on the FGEN it worked nicely.
Now since its a huge gain that i am getting right now my supervisor asked me to use a capacitor in parallel to the feedback resistor without increasing the resistor value itself. He said by that we can reduce the op amp bandwidth and solve the problem without having such high gain. Can anybody suggest me how to do it. I am sharing the op-amp datasheet and the screenshot of the circuit for your kind considerations.
The power supply decoupling capacitors are there.. Sorry they are not being shown in the diagram. the 68 mohm resistors are there to decouple them from the load. Like i said when i increased the feedback resistors to 20K the parasitic oscillation was gone. Any suggestion how to select the capacitor value that i will connect parallel to the feedback resistance (keeping its value to 1k) to get the similar behaviour. I used the equation fc= 1/(2piC*R) to determine the cutoff frequency and select the capaciotrs based on that. but it didnt work the oscilations were still there. It only goes away when I put feedback resistor value to more than 15k.
Regards,
Zakaria


texts: Embedded system - copying data from flash to RAM

texts:
This question uses some Xilinx-specific terminology.

I'm currently working with a Zynq Ultrascale+ MPSoC (CPU + FPGA in same package). I'm using a QSPI flash chip to hold the CPU configuration code, FPGA bitstream, and application (.elf). I need to transfer const data from flash to ram (external DDR) upon device initialization. There is no OS running. What's the best way to achieve this? I think I have a couple options:

1) Use BOOTGEN (flash image generation tool) to somehow store the data at a specific location in flash (not sure if this is even possible?). Then I can modify the FSBL to do a memcpy() after the DDR initialization. For the memcpy(), I would have to use the physical addresses of both the source and destination.

2) Write a C program that contains an array of const data. BOOTGEN would figure out where to locate this data in flash so I wouldn't have to worry about that. Then I could perform a memcpy() with my array as source data and a physical DDR address for the destination.

This data will eventually be accessed by the FPGA, so in either case I would have to mark out a section of DDR as reserved and non-cacheable.

Do either of these options seem reasonable? Is there a better way?


texts: inkbird ITC-708t 1850w max output pid temp controller running 2000w 120v heating element

texts: okay guys forgive me I'm just a dumb electrician/carpenter with a dream. I have caught the bug real bad in regards to home distillin. specifically still building. here is the deal, I didn't think in a million years the heating element in my kettle was over 12 amps but surprise its 16 something. i bought a ready made pid controller thinking i could plug and play until i noticed it was a 2000 watt element. So now i have to step down the voltage so i dont fry the inkbird. later i will build an inkbird 100vh with 25A ssr but for now i have got to do a flow test of my flagship still. can i just get a halogen dimmer to get me through the test? i was going to put the 20A dimmer switch in line with an amp meter and regulate it down to below 15A a little. i want to build a small still around the inkbird ITC-608t and dont want to hurt it. What say you engineers? will it work? there is a jar of awesome in it for anyone who helps!


texts: Current transformer and bridge rectifier -- why the diode drop?

texts:
I'm building a circuit to measure AC current using a current transformer, which feeds into a microcontroller's ADC for the actual measurement.

As the measurement needs to be fairly accurate, the first version had a burden resistor straight on the CT's secondary, followed by a precision rectifier/peak detector circuit using op amps. It mostly worked fine, but was expensive, so I looked for ways to replace it with something cheaper.

I found a circuit which goes like this:

Basically, the CT's secondary feeds a bridge rectifier, with the burden resistor after the rectifier.

My understanding of a CT is that the secondary acts like a current source. As such, and given that the burden resistor is the only return path for the current, then whichever current is induced on the secondary windings will be the same current that passes through the burden resistor; since the diodes have voltage drops, then the secondary winding will produce whichever voltage is required to compensate for these diode drops and force the required current through the burden resistor.

Unfortunately, this is not what I verified in practice -- the waveform was severely distorted and attenuated for low currents and much better for nominal currents (although still wrong, as verified by comparing with a current probe on the primary). I turned back to SPICE simulations, not actually expecting to see the phenomena there, but to my surprise, the simulations did show part of the problem as well -- at least the attenuation issue is clear. Simulating the circuit above produces the following output for a 5 A current on the CT's primary:

Green line is primary current, red line is secondary current times turns ratio. As can be seen, secondary current shows a 20% attenuation compared to the primary. Now for a simulation with 25 A on the CT's primary, closer to the nominal current of my circuit:

The error is close to 2% now.

Although I was sure this would make no difference, I tried replaced the silicon diode on the simulation with a Schottky diode. This improved the situation considerably, as can be seen on the following two figures, the first with 5 A and the second with 25 A on the CT's primary:

The error is about 4% for 5 A and less than 1% for 25 A.

Next step is to replace the silicon diodes on the circuit with Schottky diodes and confirm that this shows the same improvements as the simulation. I will update the post when I do this.

Clearly the diode drop needs to be taken into account, but according to my qualitative analysis of the circuit (above), this shouldn't happen. I was half expecting for it to happen in practice because of non-idealities in the CT, but I was startled to see it in simulation as well. I'm looking for insights into where my analysis went wrong, and why the diode drop is still a factor in this circuit.


texts: Is there a need for signal isolation before its measurement?

texts: A few days back, I saw a board which had an AMC1200 to isolate an input signal which is then feed to an ADC. The AMC1200 is an opto-isolation differential amplifier. I don't understand why you need to isolate a signal before measuring it. What are the advantages of isolation?


texts: Help on determining voltage differences (basic circuit theory)

texts:
I am trying to reteach myself basic circuit theory using "Practical Electronics for Inventors 3rd Edition" by Scherz and Monk.

I am working an example in which it asks to calculate the voltage difference between a variety of points (I have included a diagram below. Please note that I could not find the typical ground symbol I'm used to , so I had to use the one provided under the name GND). The example asks to find the voltage difference between points: A and C (denoted as V[sub]AC[/sub]), B and D, A and D, and B and C. Now the book lists the voltage difference between A and C as plus +3 volts and the voltage difference between A and D as +12 V, then turns around and lists the voltage between B and C as +9 volts.

I don't see how they are getting the figure for the voltage between B and C (I keep calculating -9V by the way the other two voltages were calculated).

simulate this circuit – Schematic created using CircuitLab


texts:
I am working on validating a digital link between an ad(AD9255) converter and an fpga with the PN9 PRBS sequence. The converter sends the PN9 pseudo-random sequence in 14 bit packets on a 14 bit wide digital interface. I have written in this python script the PN9 generator according to the ITU.150 standard.

reg_pn9 = 0x0092
reg_pn23 = 0x003aff
n_bits = 14
n_smpl = 20
print('PN9 sequence')
for i in range(n_smpl):
    out = 0x0000
    for j in range(0,n_bits,1):
        out = (out<<1) + ((reg_pn9 & 0x100) >> 8)
        reg_pn9 = ((reg_pn9)<<1) + ((reg_pn9 & 0x10)>>4) ^ ((reg_pn9 & 0x100)>>8)
    end = '\n'
    if(i%8 == 3):
        end = '     <<<\n' #print which number matches in the sequence
    print(hex(out), end=end)

I can reset the PN9 sequence generator with the seed value 0x092, but the python script and the ad converter's sequences doesnt match, only the every 8th number from the 3rd.
Does somebody have a tip on, how a pseudo-random sequence match like like this or there is something i am missing?
Thanks!


texts: ESD protection diodes on audio inputs / outputs?

texts:
I'm building a digital audio device with 1/4" stereo in and outputs that connect to a CS4272 codec. I'm wondering if and where I should place esd protection diodes.

Pictured below is the analog part of the circuit. The left side of the schematic connects directly to the codec.

The user could have a discharge trough the other end of a already inserted cable. Are the filter networks enough to take care of any ESD? If not, where would be the best place to place the diodes?

The datasheets of the codec and the AD8656 opamp don't mention any external protection anywhere, and after peering over the schematic of the CS4272 evaluation board I couldn't seem to spot anything there.


texts:
I am using a ULN2003 to power lamps and LEDs, and controlling them via 5v TTL.

I have some LEDs can be driven by 5v, and some lamps which require 12v.  Using the same ULN2003, can I have some powered with 5v, and some 12v, or do I need to use 2 different chips?  Of course, the grounds would be shared.

Thanks for your help in advance.

Fed


texts: VS1053 with SMD speaker, amplifier necessary?

texts:
I am working on device that looks a bit like a tablet. It consists of a display and a software controlled by touch on it. It uses the SAMA5D3 MCU from Atmel running linux.

I decided to implement audio to give the device a little bit more responsiveness and to be able to do some fancy text-to-speach stuff. I don't have space for large speakers, I found a few nice small SMD speakers around 500mW that I want to use.

I selected the well known VS1053B as the CODEC chip. VS1053 has 3 output lines, LEFT, RIGHT and GBUF.

Can I connect the SMD-Speakers (500-800mW) directely to LEFT and RIGHT, or do I have to implement an amplifier like this one: MAX98306?

How to connect the speakers? One speakers + to LEFT, the other speakers + to RIGHT and both speakers - to GBUF?

If I just want to use one speaker, can I connect LEFT to RIGHT?

Thanks for your help?


texts: 8bit shift left register with serial in, serial out implementation in verilog

texts:
I took an example from website that describes 8bit serial in serial out shift left register.

module shift (clk, si, so);
input        clk,si;
output       so;
reg    [7:0] tmp;
always @(posedge clk)
begin
   tmp    <= tmp << 1;
   tmp[0] <= si;
end
   assign so = tmp[7];
    endmodule

from above example, I think that this is strange implementation. This is because, inside always, when tmp[0] <= si; is executed first, then we will take unexpected output.

For example, let's assume si is 1, and when tmp is:

1010 1010

and, when tmp[0] <= si; is executed first(which will make an unexpected output), the output is:

0101 0110

But, if always statements are executed sequentially as it is written in above example, the output is

0101 0101

As a result, we cannot guarantee that the output could be what we expected.

Am I right? So, the correct implementation should be:

tmp <= (tmp << 1) + {7'b0000_000, si};

Or, can we prove that the above example is always executed sequentially?


texts: Expected power loss on a PoE (Power over Ethernet) device

texts:
I am just starting with PoE (Power over Ethernet), and I would like to use it to power a remote device (Buffalo WHR-HP-G54, manual here) that requires 5 volts and 2 amps DC (so, 10 watts, I assume).

If my PoE injector is capable of sending via the Ethernet cable, say, 15 watts of power, maybe the signal attenuation (power loss, or whatever is the correct way to name it, I don't know much about electronics) arrives too weak at the destination and is not capable of delivering the needed 10 watts?

Of course, I think this must depend on the Ethernet cable length and type.

This question is built with data examples in order to understand the basics of power loss for PoE.

If possible, I would like to have some sort of generic rule to calculate such power loss (maybe depending on cable length, type, etc.).

Examples of calculation rules:

Each 10 meters of UTP unshielded cable loses 1% power from the Watts max in the origin (14,85W after 10 meters, 14,7W after 20 meters, 14,55W after 30 meters, etc.).
Each 100 meters of FTP shielded cable looses a 5% power (14,25W after 100 meters, 13,5375W after 200 meters, 12,860625W after 300 meters, etc.).

Real-world example PoE injector (for those pretending exact calculations):

Reseller: TP-Link
Model: TL-POE150S
Máx power: 15.4 watts
Voltage: 48 VDC


texts: Regular ADK board vs Uno+USB Host Shield

texts:
Can anyone explain what advantages if any, there is in using a regular ADK board (Mega ADK or similar) vs using say, a Uno+ a USB host hsield?

I'm concerned about the form factor of the former.


texts:
Right now I'm reading Raspberry Pi Cookbook and I would like to create the program described in the book. Because I'm beginner and I would like to buy more (cheaper) RGB LEDs at once and also I will get them faster than the ones from link in book, so I need some help. The author of the book wrote that along of Diffused LED - RGB 10mm from Sparkfun I need three 1k ohm resistors. The problem is that I would like to buy RGB LEDs from DX or Banggood which are also smaller, but I don't know if I can use them with my Raspberry Pi and 1k ohm resistors because there are some differences between voltages looking at Sparkfun and DX/Banggood.

Basically I just need to know if I can use RGB LEDs from DX or Banggood with 1k ohm resistors and if there will not be any problem because of different voltages?


texts: Is there a way to print / draw a circuit on to clothing?

texts: I'm looking for an alternative to conductive thread (since I lack some sewing skills).  I have seen silver conductive pens but I'm wondering if they could be used for clothing?


texts: What is needed to change in this SparkFun solar charger module to reach 2A of current?

texts:
This open source product from Sparkfun (named Sunny Buddy) features Linear Instruments LT3652 MPPT li-ion/li-poly battery charger IC that can support up to 2A charging current.

Unfortunately, the board has been designed to support by default only 450mA charging current rate, but by replacing R1 sense resistor the current can be raised up.

Anyway, on this board if we lower R1 too much, the current will be too high and the inductor will actually saturate, limiting the output current artificially. If I'm correct, I calculated that the maximum achievable current should be ≈0,84A (inductor DC current = 1,05A - 20%).

But this way, if I understood how this IC works, the most of my solar panel power will be wasted.

Solar panel specifications

Voc = 9,94V
Vp = 8,54V
Vmp = 7,95V
Isc = 0,90A
Wp = 7,15W

Low power

Discharged battery voltage: 3,2V
Max current: 0,84A
Max power: 3,36W

If I could change the electronic components involved in the switching process, to reach a current of 2,0A, I'll probably get much better results:

Discharged battery voltage: 3,2V
Max current: 2,0A
Max power: 6,40W

What components should be replaced in the circuit and what board design rules should I keep in mind to let the IC work at 2.0A max?

Board schematics
Board Eagle files

Thank you in advance.


texts: Reading LM35 temperature sensor through long wire

texts:
I'm trying to read temperature through long wire, using raspberry pi.

I use mcp3008 that I power using one of my rpi 5V pins.
I use the same 5V pin to operate my LM35 temperature sensor.
The Vout of my lm35 goes into channel 0 of the mcp3008, and I use some method to read the values (irrelevant to the story)
The sensor Vout= 10mV/C, i.e 0.215V= 21.5 celcius

When I attach the sensor directly to my circuit, and try to read the values, I see the values are correct.
When I later use a twisted copper pair (telephone line), over around 5-10meters, my circuit wouldn't measure it correctly.
The readings are very inaccurate, goes around between 15-30 degrees, every second something else.
If I use a multimeter, I see the voltage is very steady, around what I sampled before (0.215V)
I have two questions in this matter:

How does the mcp3008 samples the input channel? because the voltage is OK
What simple measures I can take in order to fix it?


texts: Best power transistor for a high PWM output from ESP32

texts:
I need your advice whether to use a Tip122 Darlington transistor or a BD137 medium-power transistor Or a IRL3705 MOSFET to drive 10 Parallel infrared LEDs.
Each LED has a forward voltage of almost 1.2-1.5 V and takes 40mA of current. This makes the total current required to be 400mA. I am using a 5 V power supply which can give 2 amperes continuous current that I will apply to source/collector.
I will be using an ESP32 to generate 38 kHz pulses to the base/gate of the transistor. Keep in mind that ESP32 can provide 3.3V and very low GPIO source current (some say 12mA and others 40mA max.)
Can you tell me which one will be optimal from my usage?
I will be connecting these LEDs to the source/collector.
As from my research Tip122 may not work properly at 38Khz switching frequency, the BD137 only has a gain of 10 that means that if I am giving 40mA or 12mA of base current I may either get 400mA or 120mA (extra doesn't hurt but having less definitely does).
IRL3705 is expensive and also has Vgs(th) of 2V maximum, meaning that either it may not work correctly or it would have a high Rds(on).

P.S. You can see the picture attached for 4 of these LEDs and you can imagine the rest of 10 of these. The picture would be same if I am using a n-channel enhancement MOSFET.


texts:
This is a really basic question I know, I am just doubting myself for some reason.
I am trying to make a power distribution board. I have a 12v power supply rated to 20A.

If I arrange my DC Jacks in the following way:

If have devices requiring 2A supply connected to J1 - J5 and devices requiring a 1A supply J6-J13 my total would be 18A giving me a 90% load?

Have I got my maths/layout right, with the layers of parallel sockets?

Is there something I am missing?


texts: Frequency response across component in ltSpice

texts: How do I find frequency response across a component not referenced to ground.


texts: How does the buck regulator soft start condition reduce the unwanted voltage drops from high impedance power sources?

texts:
I have been studying the functionality of the soft start function. I understood how it will help to reduce the overshoot of the output voltage as well. Here, my intention is to understand the meaning of following highlighted terms.
Any explanation with a practical scenario would be helpful.


texts: Differential Driver Maximum Output Voltage Swing

texts:
I'm trying to understand how BTL driver on TI's DRV8662 Piezo Haptic Driver (datasheet) works. What I am confused about is how a 200Vpp output signal can be generated from a driver that only has rails at GND and 100V. If I understand that datasheet correctly the driver looks something like this:

The output according to the datasheet is this:

What I am confused about is that the differential outputs have a common mode voltage of 50V (as shown in figure 8). So how is the voltage difference in between Out+ and Out- signals leads to a 200Vpp swing (as in figure 10) when figure 8 clearly shows that the maximum difference between these two voltages is 100V? How can the output swing to -100V if no negative rail is ever supplied to the part?

I tried reading these documents to clear up my issue but it didn't help.

BTL Speakerdrive Reference Note (link)

Audio Design Note (link)


texts: HCPL3700M optocoupler: why is pulse generator connected to both AC and DC pins?

texts:
I'm reading the datasheet for the HCPL3700M AC/DC to Logic Interface Optocoupler.  In a test circuit diagram, it shows a pulse generator connected to both the AC and DC pins (see attached).

Why would it need to go to both?
Why is the pulse connected to the ground on the logic side?  Is the purpose not to keep higher voltage AC separated from the logic side?

The datasheet can be found here: https://www.mouser.com/datasheet/2/308/HCPL3700M-1306568.pdf

Thanks!


texts:
I have designed a PCB in Eagle. I have doubt regarding creating the ground planes.  I have created a ground plane on the top layer only

But I even have connections in the bottom layer too which are nothing but the ground connections to the MCU.

Do I have to make another ground plane in the bottom layer for sure or can I order my PCB right away?
If I have to create ground on bottom layer, too: Do I have to connect the top and bottom layer ground planes using VIAs?

Antenna Datasheet

Datasheet of the MCU used


texts: Programming a parallel port as digital I/O

texts:
I'm trying to use a parallel port from a computer as a form of cheap digital output to do various things (control motors, light LEDs, read limit switches, ect).

I want to know how to control the 8 data pins on a parallel port using C++, however there's a catch. Since I'm using a modern computer with a modern OS, this presents a few problems.

First of all, modern windows OS's don't allow direct access to parallel port pins, I must go through a driver. I have been pointed to using Inpout32 to do this, however the sample program compiled and ran properly but my attached hardware didn't respond. Another person has pointed me to using Windows API. I have searched the MSDN and found only mentions of the appropriate function but without some sample code, I'm lost (maybe I'm searching in the wrong places).

The second problem is that my new computer doesn't have any parallel ports. I must use USB to parallel ports instead (cheap and direct from China, $5 each, shipping and taxes all included). The ports are recognized by the computer as IEEE-1284 controllers and the appropriate drivers were automatically installed and the computer reports the device as "working properly". From what i have seen online, there seems to be a wide variety of opinions on the usefulness of these USB to parallel port connectors. One person says it works perfectly fine like any regular parallel port soldered to the motherboard, another says it will work with some hardware hacks, one says it can write but not read, and finally another says it won't work at all because they are not designed to work the same way as "real" parallel ports.

I have already done a great deal of research before coming here (sort of as a last resort I guess, StackOverflow didn't yield any answers even after applying a bounty). Pretty much all the information I found on programming parallel ports is outdated and assumes that you have either a parallel port on your motherboard, a pre-Windows-NT OS, or both.

If anyone has any idea how to do this, would you please share it with me?

Thanks,

-Faken

Note: I'm running Windows 7 x64 OS on a Core i7 860. I'm programming in C++ on Visual Studio 2008 pro. The USB to parallel port connectors are connected via USB 2.0 ports.


texts: Interfacing to a Microprocessor Bus without an 8255

texts:
There are 32 doors in a building each having a sensor attached with it. Each door outputs a signal 1 if it is open and O if closed. I want to design a pc based  system to display the condition of each door(open/closed) on the computer screen using parallel port interfacing by 8 bit data transfer at a time.

I have made a design using intel 8255 PPI and 8 MUX. PORT A of 8255 has been used as input and two pins of Port C has been used as the selector bits of each MUX.

My question is if it is possible to make the design without using 8255 PPI, by making direct connection with the microprocessor? If so, then how?


texts: How to switch continuity direction on a grid?

texts:
Please bear with me here. I haven't had to do much circuit design since my MechE days in college, so I'm very rusty.

I'm working on a project where I need to be able to take a grid of conductive squares (say a piece of perfboard) and create alternating lines of continuity. In one moment there would be horizontal continuity, and in the next moment there would be vertical continuity, as shown:

I'm getting stuck on figuring out how to make this work. I've been going back and reviewing simple transistor switches, but those seem to be concerned with switching current across a load, whereas what I need to do is switch the high (+5V) signal continuity, without necessarily causing any current unless there happens to be a component touching one of the "high lines" and "ground lines" at a given moment.

One of the main challenges, as you can see, is that it's not enough to simply change where the voltage is applied at the edges. Continuity between individual grid squares has to be broken and created each time the lines switch from horizontal to vertical.

Any and all help would be much appreciated. Thanks.

EDIT:

Based on Dave Tweed's square wave idea, I sketched out the following circuit. This is my best guess about what you meant for using two out-of-phase square waves. Is this correct? If I understand correctly, this will result in the connected squares alternating between +5V and Gnd? (Sketch below)

If this is correct, I assume that for the other "switching" squares, I would duplicate this circuit and reverse the signal inputs? Thanks again.


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I am confused how a the high side mosfets in this diagram stay on once enabled. When turned on presumably most of the voltage is dropped across the motor coil, and so the voltage across the mosfet will be small.
So the voltage at the source and the voltage at the drain are similar, and assuming I am using the same voltage on the gate and hooked up to drain, does this not now mean that Vgs will not be large enough for the mosfet to switch on?


texts: Is there a preferred order in which to apply (analog) filters in a chain?

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I'm working on a project where a very weak signal need to pass through a bunch of filters. However, I am seeing quite a lot of different ways in which the order of the various filter stages are applied. So my question is:

Is there a preferred order in which to apply different filters in an analog  signal chain?

For example:

[weak signal sensor] (input)
--> [10 kHz LPF]
--> InAmp
--> [50Hz Notch (active)]
--> [500 Hz LPF-2]
--> [20 Hz HPF]
--> ADC (output)

There is a similar question here but clear answers are lacking and is not related to very weak signals.

I'm looking to understand why, for example (above), one want to pre-filter the input before the IA, or in other cases where people decide to place a HPF before LPF. The only thing I have read (from Texas Instruments docs) is that one should apply the greatest gain as late as possible, but that also seem to vary.


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I bought some DC-DC buck converters which are supposedly adjustable.
They have a tiny trim potentiometer on them, but how are those adjusted? I tried my tinyest screwdriver, but it simply won't turn.
I tried on all 5 of them, and tried 10 different screwdrivers, this has me puzzled


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I have installed Altium Designer 19 recently but I have two problems with this version:

First of all, when I open the layer stack manager I can not see "save and load and advance" at bottom. I don't know how to fix this issue!

Second, when I am in Gerber setup menu I can not see this option "board outline".

Sorry if my questions look very weird, but I don't have as much experience with Altium Designer as most of you guys.


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This is the pinout for the internal screen connector of a 1986 Toshiba T3100SX 'laptop'. The screen itself is a orange neon gas plasma display (although they also made some with an LCD).

Does anyone know what the protocol is?

This pinout comes from the maintenance manual, which is very patchy regarding technical information --- so the above is all I've got. I know that DSPV is probably +12V. PDP and COLOR will be used to tell the video hardware whether the laptop has the gas plasma or LCD screen plugged in, and I bet that BRCNTM is something to do with brightness. The numbers after the pins are significant, but I don't know what they mean yet.

The screen will display VGA with 16-colour greyscale, so it's probably really simply clocking the pixels in at the right rate. The four-bit wide buses corroborate that. I'm not sure why there are two, though; left and right? Also I'd expect to see lines for horizontal and vertical sync, so unless these are what LP and FP are, then I'm wrong.

The motherboard itself seems to use a bunch of custom ASICs to generate the signal, so there's no help there.

I'm sure someone should be able to tell at a glance what this is. Any ideas?


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I went through a video on Youtube [2:42], that described "key difference" between a microcontroller and microprocess, apart from other differences, is that "microcontroller has a strong I/O capability so that they can derive external hardware directly, while microprocessor has weak I/O which needs  transisitors to drive external hardware"

I really didnt understand why is that. Both microcontroller and microprocessor require transistors to drive external hardware. What am I missing?

This question is not pertaining to mere microcontrollers vs microprocessors, it is focused on a single distinction of "proficiency of driving external hardware"


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I am working on a system which should communicate with a ~100kHz signal, and read that low frequency channels, e.g 10kHz to 200kHz, are especially susceptible to interference.

Why is that? Are they more susceptible than say a 500Hz signal?


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texts: Rather new to electronics, I'm trying to design some of my first circuits. One of them includes a bridge rectifier feeding into an opamp used as a comparator. However, I'm a bit perplexed as to why LTSpice shows the input voltage as consistently negative, regardless of where in the sine wave the input voltage component is at/should be.  I've tried reversing the polarity of the voltage component, reversing the leads that feed the bridge, and the like but seem to get the same result.  The input voltage is above zero at about +1V (I'm assuming due to 2X the voltage drop of the diodes used) for part of the cycle - inverting the concept of a diode "voltage drop".  Is the voltage really driving negative or is this an artifact of LTSpice modeling?  In either case, is there a way to change this?